fix: correct token/cost double-counting in usage tracker

Remove the StepUsageEvent handler from subscribeSDKEvents. It was
calling UpdateUsage() for every individual tool-calling step as it
streamed, then updateUsageFromTurnResult() called UpdateUsage() again
with TotalUsage (fantasy's own aggregate of all steps). A turn with N
tool calls was counting every token N+1 times.

Fix updateUsageFromTurnResult to use a single, clean code path:
- UpdateUsage() called exactly once per turn using TotalUsage
- SetContextTokens() uses FinalUsage.InputTokens only (not +OutputTokens)
  since input tokens of the last call = actual context window fill;
  output tokens are the response length, not context occupancy
- Estimate fallback no longer early-returns before SetContextTokens

Verified with opencode/kimi-k2.5: cost accumulates linearly across
simple and multi-step tool-calling turns with no double-counting.
anthropic/claude-sonnet-4-6 correctly shows $0.00 for OAuth sessions.

.gitignore

@@ -1,7 +1,8 @@
 .aider*
 .task/
 .env
-.kit/
+.kit/*
+!.kit/extensions/
 aidocs/
 *.log
 /kit

.kit/extensions/go-edit-lint.go

@@ -0,0 +1,228 @@
+//go:build ignore
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"kit/ext"
+)
+
+const (
+	diagnosticsTimeout = 20 * time.Second
+	maxOutputBytes     = 12_000
+)
+
+type toolPathInput struct {
+	Path string `json:"path"`
+}
+
+type lintResult struct {
+	Output string
+	Err    error
+}
+
+func Init(api ext.API) {
+	api.OnSessionStart(func(_ ext.SessionStartEvent, ctx ext.Context) {
+		ctx.Print("go-edit-lint extension loaded - will run gopls and golangci-lint on Go file edits")
+	})
+
+	api.OnToolResult(func(e ext.ToolResultEvent, ctx ext.Context) *ext.ToolResultResult {
+		if e.IsError || !isEditOrWrite(e.ToolName) {
+			return nil
+		}
+
+		absPath, ok := resolveGoFilePath(e.Input, ctx.CWD)
+		if !ok {
+			return nil
+		}
+
+		report := runGoDiagnostics(ctx.CWD, absPath)
+		
+		// Check if there are issues and add explicit prompt for the LLM to react
+		goplsIssues, lintIssues := countIssues(report)
+		hasIssues := goplsIssues > 0 || lintIssues > 0
+		
+		var enhanced string
+		if hasIssues {
+			enhanced = e.Content + "\n\n" + report + "\n\n⚠️ DIAGNOSTICS FOUND: Please review the issues above and fix them before proceeding."
+		} else {
+			enhanced = e.Content + "\n\n" + report
+		}
+
+		// Show TUI message block for diagnostics visibility (only if there are issues)
+		if hasIssues {
+			var msgLines []string
+			msgLines = append(msgLines, fmt.Sprintf("File: %s", filepath.Base(absPath)))
+			if goplsIssues > 0 {
+				msgLines = append(msgLines, fmt.Sprintf("gopls: %d issue(s)", goplsIssues))
+			}
+			if lintIssues > 0 {
+				msgLines = append(msgLines, fmt.Sprintf("golangci-lint: %d issue(s)", lintIssues))
+			}
+			msgLines = append(msgLines, "", "⚠️ Please fix these issues before proceeding.")
+
+			borderColor := "#f9e2af" // yellow
+			if goplsIssues > 0 && lintIssues > 0 {
+				borderColor = "#f38ba8" // red
+			}
+
+			ctx.PrintBlock(ext.PrintBlockOpts{
+				Text:        strings.Join(msgLines, "\n"),
+				BorderColor: borderColor,
+				Subtitle:    "go-edit-lint",
+			})
+		}
+
+		return &ext.ToolResultResult{Content: &enhanced}
+	})
+}
+
+func isEditOrWrite(toolName string) bool {
+	return strings.EqualFold(toolName, "edit") || strings.EqualFold(toolName, "write")
+}
+
+func resolveGoFilePath(inputJSON, cwd string) (string, bool) {
+	var args toolPathInput
+	if err := json.Unmarshal([]byte(inputJSON), &args); err != nil || args.Path == "" {
+		return "", false
+	}
+
+	absPath := args.Path
+	if !filepath.IsAbs(absPath) {
+		absPath = filepath.Join(cwd, absPath)
+	}
+
+	if strings.ToLower(filepath.Ext(absPath)) != ".go" {
+		return "", false
+	}
+
+	return absPath, true
+}
+
+func runGoDiagnostics(cwd, absPath string) string {
+	gopls := runGopls(cwd, absPath)
+	lint := runGolangCILint(cwd, "./...")
+
+	return fmt.Sprintf(
+		"<go_diagnostics file=%q>\n[gopls]\n%s\n\n[golangci-lint]\n%s\n</go_diagnostics>",
+		filepath.Base(absPath),
+		formatToolResult(gopls, "No diagnostics."),
+		formatToolResult(lint, "No lint issues."),
+	)
+}
+
+func runGopls(cwd, absPath string) lintResult {
+	ctx, cancel := context.WithTimeout(context.Background(), diagnosticsTimeout)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "gopls", "check", absPath)
+	cmd.Dir = cwd
+	out, err := cmd.CombinedOutput()
+
+	if ctx.Err() == context.DeadlineExceeded {
+		return lintResult{Err: fmt.Errorf("timed out after %s", diagnosticsTimeout)}
+	}
+
+	if err != nil {
+		return lintResult{Output: truncate(string(out), maxOutputBytes), Err: fmt.Errorf("failed to run gopls check: %w", err)}
+	}
+
+	return lintResult{Output: truncate(string(out), maxOutputBytes)}
+}
+
+func runGolangCILint(cwd, target string) lintResult {
+	ctx, cancel := context.WithTimeout(context.Background(), diagnosticsTimeout)
+	defer cancel()
+
+	args := []string{
+		"run",
+		target,
+		"--show-stats=false",
+		"--output.text.path", "stdout",
+		"--output.text.colors=false",
+		"--output.text.print-issued-lines=false",
+	}
+	cmd := exec.CommandContext(ctx, "golangci-lint", args...)
+	cmd.Dir = cwd
+	out, err := cmd.CombinedOutput()
+
+	if ctx.Err() == context.DeadlineExceeded {
+		return lintResult{Err: fmt.Errorf("timed out after %s", diagnosticsTimeout)}
+	}
+
+	trimmed := truncate(string(out), maxOutputBytes)
+	if err == nil {
+		return lintResult{Output: trimmed}
+	}
+
+	exitErr, ok := err.(*exec.ExitError)
+	if ok && exitErr.ExitCode() == 1 {
+		return lintResult{Output: trimmed}
+	}
+
+	return lintResult{Output: trimmed, Err: fmt.Errorf("failed to run golangci-lint: %w", err)}
+}
+
+func formatToolResult(res lintResult, emptyFallback string) string {
+	var lines []string
+	if res.Err != nil {
+		lines = append(lines, "ERROR: "+res.Err.Error())
+	}
+	out := strings.TrimSpace(res.Output)
+	if out == "" {
+		if res.Err == nil {
+			lines = append(lines, emptyFallback)
+		}
+	} else {
+		lines = append(lines, out)
+	}
+	if len(lines) == 0 {
+		return emptyFallback
+	}
+	return strings.Join(lines, "\n")
+}
+
+func truncate(s string, max int) string {
+	if len(s) <= max {
+		return s
+	}
+	return s[:max] + "\n... output truncated ..."
+}
+
+func countIssues(report string) (goplsCount, lintCount int) {
+	// Extract gopls section
+	goplsStart := strings.Index(report, "[gopls]")
+	lintStart := strings.Index(report, "[golangci-lint]")
+	endTag := strings.Index(report, "</go_diagnostics>")
+
+	if goplsStart != -1 && lintStart != -1 {
+		goplsSection := report[goplsStart:lintStart]
+		// Count non-empty lines excluding the header and "No diagnostics." message
+		for _, line := range strings.Split(goplsSection, "\n") {
+			line = strings.TrimSpace(line)
+			if line != "" && line != "[gopls]" && line != "No diagnostics." {
+				goplsCount++
+			}
+		}
+	}
+
+	if lintStart != -1 && endTag != -1 {
+		lintSection := report[lintStart:endTag]
+		// Count non-empty lines excluding the header and "No lint issues." message
+		for _, line := range strings.Split(lintSection, "\n") {
+			line = strings.TrimSpace(line)
+			if line != "" && line != "[golangci-lint]" && line != "No lint issues." {
+				lintCount++
+			}
+		}
+	}
+
+	return goplsCount, lintCount
+}

.kit/extensions/subagent-monitor.go

@@ -0,0 +1,304 @@
+//go:build ignore
+
+// subagent-monitor — live horizontal widget strip for spawned subagents
+//
+// Subscribes to subagents spawned by the main Kit agent and displays a
+// single widget just above the input box. Each subagent occupies one column
+// in a side-by-side horizontal layout. Columns show scrolling real-time
+// output as the subagent works. When a subagent finishes its column is
+// removed automatically.
+//
+// Yaegi-safe design notes:
+// - No sync.Mutex (Yaegi has reflection issues with sync primitives)
+// - No channels in maps (Yaegi panics on range over map[string]chan)
+// - All ctx.* calls guarded with nil checks
+// - Simple data structures only
+package main
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"kit/ext"
+)
+
+// ---------------------------------------------------------------------------
+// Per-subagent state
+// ---------------------------------------------------------------------------
+
+type submonEntry struct {
+	id      int
+	callID  string
+	task    string
+	lines   []string
+	started time.Time
+	elapsed time.Duration
+}
+
+const (
+	submonColWidth = 34 // visible character width per column
+	submonMaxLines = 5  // scrolling output lines per column
+	submonColGap   = 2  // spaces between columns
+)
+
+// ---------------------------------------------------------------------------
+// Package-level state - all simple types
+// ---------------------------------------------------------------------------
+
+var (
+	submonCtx     ext.Context
+	submonHasCtx  bool
+	submonEntries []*submonEntry
+	submonNextID  int
+)
+
+func submonInit() {
+	submonEntries = nil
+	submonNextID = 1
+}
+
+// ---------------------------------------------------------------------------
+// String helpers
+// ---------------------------------------------------------------------------
+
+func submonPad(s string, w int) string {
+	r := []rune(s)
+	if len(r) >= w {
+		return string(r[:w])
+	}
+	return s + strings.Repeat(" ", w-len(r))
+}
+
+func submonTrunc(s string, w int) string {
+	r := []rune(s)
+	if len(r) <= w {
+		return s
+	}
+	if w <= 1 {
+		return "…"
+	}
+	return string(r[:w-1]) + "…"
+}
+
+// ---------------------------------------------------------------------------
+// Widget rendering
+// ---------------------------------------------------------------------------
+
+func submonRenderColumn(e *submonEntry) []string {
+	var rows []string
+
+	// Calculate elapsed time on-demand to avoid race conditions with ticker
+	elapsed := e.elapsed
+	if elapsed == 0 && !e.started.IsZero() {
+		elapsed = time.Since(e.started)
+	}
+	secs := int(elapsed.Seconds())
+	timeStr := fmt.Sprintf("%ds", secs)
+	taskMax := submonColWidth - len(timeStr) - 3
+	taskPart := submonTrunc(e.task, taskMax)
+	header := fmt.Sprintf("#%d %s  %s", e.id, taskPart, timeStr)
+	rows = append(rows, submonPad(header, submonColWidth))
+
+	display := e.lines
+	if len(display) > submonMaxLines {
+		display = display[len(display)-submonMaxLines:]
+	}
+	for _, l := range display {
+		rows = append(rows, submonPad("  "+submonTrunc(l, submonColWidth-2), submonColWidth))
+	}
+	for len(rows) < submonMaxLines+1 {
+		if len(rows) == 1 && len(e.lines) == 0 {
+			rows = append(rows, submonPad("  waiting…", submonColWidth))
+		} else {
+			rows = append(rows, strings.Repeat(" ", submonColWidth))
+		}
+	}
+	return rows
+}
+
+func submonBuildWidget() string {
+	if len(submonEntries) == 0 {
+		return ""
+	}
+
+	numCols := len(submonEntries)
+	numRows := submonMaxLines + 1
+	cols := make([][]string, numCols)
+	for i, e := range submonEntries {
+		rows := submonRenderColumn(e)
+		col := make([]string, numRows)
+		for j := 0; j < numRows; j++ {
+			if j < len(rows) {
+				col[j] = rows[j]
+			} else {
+				col[j] = strings.Repeat(" ", submonColWidth)
+			}
+		}
+		cols[i] = col
+	}
+
+	gap := strings.Repeat(" ", submonColGap)
+	var sb strings.Builder
+	for row := 0; row < numRows; row++ {
+		for ci := range cols {
+			if ci > 0 {
+				sb.WriteString(gap)
+			}
+			sb.WriteString(cols[ci][row])
+		}
+		if row < numRows-1 {
+			sb.WriteString("\n")
+		}
+	}
+	return sb.String()
+}
+
+func submonPushWidget() {
+	if !submonHasCtx {
+		return
+	}
+	if submonCtx.SetWidget == nil {
+		return
+	}
+
+	text := submonBuildWidget()
+	if len(submonEntries) == 0 {
+		if submonCtx.RemoveWidget != nil {
+			submonCtx.RemoveWidget("submon")
+		}
+		return
+	}
+	submonCtx.SetWidget(ext.WidgetConfig{
+		ID:        "submon",
+		Placement: ext.WidgetAbove,
+		Content:   ext.WidgetContent{Text: text},
+		Style:     ext.WidgetStyle{BorderColor: "#89b4fa"},
+		Priority:  0,
+	})
+}
+
+func submonAppendLine(e *submonEntry, line string) {
+	line = strings.TrimRight(line, "\r\n")
+	if strings.TrimSpace(line) == "" {
+		return
+	}
+	e.lines = append(e.lines, line)
+}
+
+// ---------------------------------------------------------------------------
+// Init
+// ---------------------------------------------------------------------------
+
+func Init(api ext.API) {
+	submonInit()
+
+	api.OnSessionStart(func(_ ext.SessionStartEvent, ctx ext.Context) {
+		submonCtx = ctx
+		submonHasCtx = true
+		submonInit()
+		if ctx.RemoveWidget != nil {
+			ctx.RemoveWidget("submon")
+		}
+	})
+
+	api.OnAgentEnd(func(_ ext.AgentEndEvent, ctx ext.Context) {
+		submonCtx = ctx
+		submonHasCtx = true
+	})
+
+	// ── SubagentStart ────────────────────────────────────────────────────────
+	api.OnSubagentStart(func(e ext.SubagentStartEvent, ctx ext.Context) {
+		submonCtx = ctx
+		submonHasCtx = true
+
+		id := submonNextID
+		submonNextID++
+		entry := &submonEntry{
+			id:      id,
+			callID:  e.ToolCallID,
+			task:    e.Task,
+			started: time.Now(),
+		}
+		submonEntries = append(submonEntries, entry)
+
+		submonPushWidget()
+	})
+
+	// ── SubagentChunk ────────────────────────────────────────────────────────
+	api.OnSubagentChunk(func(e ext.SubagentChunkEvent, ctx ext.Context) {
+		submonCtx = ctx
+		submonHasCtx = true
+
+		var entry *submonEntry
+		for _, en := range submonEntries {
+			if en.callID == e.ToolCallID {
+				entry = en
+				break
+			}
+		}
+		if entry == nil {
+			return
+		}
+
+		switch e.ChunkType {
+		case "text":
+			for _, line := range strings.Split(e.Content, "\n") {
+				submonAppendLine(entry, line)
+			}
+		case "tool_call":
+			submonAppendLine(entry, "→ "+e.ToolName)
+		case "tool_execution_start":
+			submonAppendLine(entry, "⚙ "+e.ToolName)
+		case "tool_result":
+			if e.IsError {
+				submonAppendLine(entry, "✗ "+e.ToolName)
+			} else {
+				submonAppendLine(entry, "✓ "+e.ToolName)
+			}
+		}
+
+		submonPushWidget()
+	})
+
+	// ── SubagentEnd ──────────────────────────────────────────────────────────
+	api.OnSubagentEnd(func(e ext.SubagentEndEvent, ctx ext.Context) {
+		submonCtx = ctx
+		submonHasCtx = true
+
+		var entry *submonEntry
+		for _, en := range submonEntries {
+			if en.callID == e.ToolCallID {
+				entry = en
+				break
+			}
+		}
+		if entry != nil {
+			entry.elapsed = time.Since(entry.started)
+			if e.ErrorMsg != "" {
+				submonAppendLine(entry, "✗ "+submonTrunc(e.ErrorMsg, submonColWidth-2))
+			}
+		}
+
+		submonPushWidget()
+
+		// Remove the entry immediately (no goroutine to avoid races)
+		newEntries := submonEntries[:0]
+		for _, en := range submonEntries {
+			if en.callID != e.ToolCallID {
+				newEntries = append(newEntries, en)
+			}
+		}
+		submonEntries = newEntries
+		submonPushWidget()
+	})
+
+	// ── SessionShutdown ──────────────────────────────────────────────────────
+	api.OnSessionShutdown(func(_ ext.SessionShutdownEvent, ctx ext.Context) {
+		submonInit()
+		// Guard ctx access - may be nil during shutdown
+		if ctx.RemoveWidget != nil {
+			ctx.RemoveWidget("submon")
+		}
+	})
+}

README.md

@@ -21,7 +21,9 @@ A powerful, extensible AI coding agent CLI with multi-provider support, built-in
 - **Built-in Core Tools**: bash, read, write, edit, grep, find, ls, spawn_subagent - no MCP overhead
 - **MCP Integration**: Connect external MCP servers for expanded capabilities
 - **Extension System**: Write custom tools, commands, widgets, and UI modifications in Go
-- **Theming**: 22 built-in color themes (KITT, Catppuccin, Dracula, Nord, etc.) with runtime switching and custom theme files
+- **Theming**: 22 built-in color themes (KITT, Catppuccin, Dracula, Nord, etc.) with runtime switching, persistence, and custom theme files
+- **Model Persistence**: Model and thinking level selections are automatically saved and restored across sessions
+- **Prompt Templates**: Create reusable prompt templates with shell-style argument substitution
 - **Interactive TUI**: Rich terminal interface powered by Bubble Tea with streaming, syntax highlighting, and custom rendering
 - **Session Management**: Tree-based conversation history with branching support
 - **Non-Interactive Mode**: Script-friendly positional args with JSON output
@@ -71,6 +73,9 @@ kit @main.go @test.go "Review these files"
 # Continue the most recent session
 kit --continue
 
+# Model and thinking level selections are automatically persisted
+# across sessions and restored on next launch
+
 # Use specific model
 kit --model anthropic/claude-sonnet-latest
 ```
@@ -177,6 +182,8 @@ mcpServers:
 # Extensions
 --extension, -e          Load additional extension file(s) (repeatable)
 --no-extensions          Disable all extensions
+--prompt-template        Load a specific prompt template by name
+--no-prompt-templates    Disable prompt template loading
 
 # Generation parameters
 --max-tokens             Maximum tokens in response (default: 4096)
@@ -232,6 +239,8 @@ Kit ships with 22 built-in color themes that control all UI elements. Switch at
 /theme tokyonight
 ```
 
+Theme selections are automatically saved and restored on next launch (stored in `~/.config/kit/preferences.yml`). This persistence also applies to **model** and **thinking level** selections — all are saved together and restored on startup.
+
 ### Custom themes
 
 Drop a `.yml` file in `~/.config/kit/themes/` (user) or `.kit/themes/` (project):
@@ -278,7 +287,7 @@ kit -e examples/extensions/minimal.go
 
 ### Extension Capabilities
 
-**Lifecycle Events**: OnSessionStart, OnSessionShutdown, OnBeforeAgentStart, OnAgentStart, OnAgentEnd, OnToolCall, OnToolExecutionStart, OnToolExecutionEnd, OnToolResult, OnInput, OnMessageStart, OnMessageUpdate, OnMessageEnd, OnModelChange, OnContextPrepare, OnBeforeFork, OnBeforeSessionSwitch, OnBeforeCompact
+**Lifecycle Events**: OnSessionStart, OnSessionShutdown, OnBeforeAgentStart, OnAgentStart, OnAgentEnd, OnToolCall, OnToolExecutionStart, OnToolOutput, OnToolExecutionEnd, OnToolResult, OnInput, OnMessageStart, OnMessageUpdate, OnMessageEnd, OnModelChange, OnContextPrepare, OnBeforeFork, OnBeforeSessionSwitch, OnBeforeCompact, OnCustomEvent, OnSubagentStart, OnSubagentChunk, OnSubagentEnd
 
 **Custom Components**:
 - **Tools**: Add new tools the LLM can invoke
@@ -332,6 +341,8 @@ See the `examples/extensions/` directory:
 - `tool-renderer-demo.go` - Custom tool call rendering
 - `widget-status.go` - Persistent status widgets
 
+Also see `.kit/extensions/go-edit-lint.go` (in this repo) for a project-local extension example that runs gopls and golangci-lint on Go file edits.
+
 ### Loading Extensions
 
 **Auto-discovery** (loads automatically):
@@ -389,6 +400,32 @@ func TestMyExtension(t *testing.T) {
 
 See `examples/extensions/tool-logger_test.go` for a complete example with 14 test cases covering tool calls, input handling, and session lifecycle.
 
+### Prompt Templates
+
+Create reusable prompt templates with shell-style argument substitution. Templates are loaded from `~/.kit/prompts/*.md` and `.kit/prompts/*.md`.
+
+**Example template** (`~/.kit/prompts/review.md`):
+```markdown
+---
+description: Review code for issues
+---
+Review the following code for bugs and security issues.
+Focus on $1 specifically.
+```
+
+**Usage:**
+```
+/review error handling
+```
+
+**Argument placeholders:**
+- `$1`, `$2`, etc. — Individual arguments
+- `$@` or `$ARGUMENTS` — All arguments
+- `${@:2}` — Arguments from position 2 onwards
+- `${@:1:3}` — 3 arguments starting at position 1
+
+Disable templates with `--no-prompt-templates` or load a specific template with `--prompt-template <name>`.
+
 ## Session Management
 
 Kit uses a tree-based session model that supports branching and forking conversations.
@@ -419,6 +456,22 @@ kit -s path/to/session.jsonl
 kit --no-session
 ```
 
+### Interactive Session Commands
+
+During an interactive session, use these slash commands:
+
+| Command | Description |
+|---------|-------------|
+| `/name [name]` | Set or display the session's display name |
+| `/session` | Show session info (path, ID, message count) |
+| `/resume` | Open the session picker to switch sessions |
+| `/export [path]` | Export session as JSONL (auto-generates path if omitted) |
+| `/import <path>` | Import and switch to a session from a JSONL file |
+| `/share` | Upload session to GitHub Gist and get a shareable viewer URL |
+| `/tree` | Navigate the session tree |
+| `/fork` | Branch from an earlier message |
+| `/new` | Start a fresh session |
+
 ## Go SDK
 
 Embed Kit in your Go applications:
@@ -651,8 +704,24 @@ npm/                 - NPM package wrapper for distribution
 - **Google Vertex** - Claude on Vertex AI
 - **OpenRouter** - Multi-provider router
 - **Vercel AI** - Vercel AI SDK models
+- **Custom** - Any OpenAI-compatible endpoint via `--provider-url`
 - **Auto-routed** - Any provider from models.dev database
 
+### Custom Provider
+
+Use `custom/custom` when pointing Kit at any OpenAI-compatible endpoint with `--provider-url`:
+
+```bash
+kit --provider-url "http://localhost:8080/v1" "Hello"
+```
+
+This automatically defaults to `custom/custom` without needing to specify a model. The custom provider routes through fantasy's `openaicompat` provider and supports:
+
+- Zero cost tracking (input/output = 0)
+- 262K context window, 65K output limit
+- Reasoning and temperature support
+- Optional `CUSTOM_API_KEY` environment variable or `--provider-api-key` flag
+
 ### Model String Format
 
 ```bash

cmd/auth.go

@@ -1,9 +1,13 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
+	"net"
+	"net/http"
 	"os"
 	"strings"
+	"time"
 
 	"charm.land/huh/v2"
 	"github.com/mark3labs/kit/internal/auth"
@@ -14,7 +18,7 @@ import (
 // authCmd represents the auth command for managing AI provider authentication.
 // This command provides subcommands for login, logout, and status checking
 // of authentication credentials for various AI providers, with OAuth support
-// for providers like Anthropic.
+// for providers like Anthropic and OpenAI.
 var authCmd = &cobra.Command{
 	Use:   "auth",
 	Short: "Manage authentication credentials for AI providers",
@@ -25,9 +29,11 @@ using OAuth flows. Stored credentials take precedence over environment variables
 
 Available providers:
   - anthropic: Anthropic Claude API (OAuth)
+  - openai:    OpenAI API (OAuth and API key)
 
 Examples:
   kit auth login anthropic
+  kit auth login openai
   kit auth logout anthropic
   kit auth status`,
 }
@@ -46,9 +52,11 @@ environment variables when making API calls.
 
 Available providers:
   - anthropic: Anthropic Claude API (OAuth)
+  - openai:    OpenAI ChatGPT Plus/Pro (Codex OAuth)
 
 Example:
-  kit auth login anthropic`,
+  kit auth login anthropic
+  kit auth login openai`,
 	Args: cobra.ExactArgs(1),
 	RunE: runAuthLogin,
 }
@@ -61,14 +69,16 @@ var authLogoutCmd = &cobra.Command{
 	Short: "Remove stored authentication credentials for a provider",
 	Long: `Remove stored authentication credentials for an AI provider.
 
-This will delete the stored API key for the specified provider. You will need
-to use environment variables or command-line flags for authentication after logout.
+This will delete the stored API key or OAuth credentials for the specified provider. 
+You will need to use environment variables or command-line flags for authentication after logout.
 
 Available providers:
   - anthropic: Anthropic Claude API
+  - openai:    OpenAI API
 
 Example:
-  kit auth logout anthropic`,
+  kit auth logout anthropic
+  kit auth logout openai`,
 	Args: cobra.ExactArgs(1),
 	RunE: runAuthLogout,
 }
@@ -101,8 +111,10 @@ func runAuthLogin(cmd *cobra.Command, args []string) error {
 	switch provider {
 	case "anthropic":
 		return loginAnthropic()
+	case "openai":
+		return loginOpenAI()
 	default:
-		return fmt.Errorf("unsupported provider: %s. Available providers: anthropic", provider)
+		return fmt.Errorf("unsupported provider: %s. Available providers: anthropic, openai", provider)
 	}
 }
 
@@ -112,8 +124,10 @@ func runAuthLogout(cmd *cobra.Command, args []string) error {
 	switch provider {
 	case "anthropic":
 		return logoutAnthropic()
+	case "openai":
+		return logoutOpenAI()
 	default:
-		return fmt.Errorf("unsupported provider: %s. Available providers: anthropic", provider)
+		return fmt.Errorf("unsupported provider: %s. Available providers: anthropic, openai", provider)
 	}
 }
 
@@ -157,8 +171,44 @@ func runAuthStatus(cmd *cobra.Command, args []string) error {
 		}
 	}
 
+	// Check OpenAI credentials
+	fmt.Print("\nOpenAI: ")
+	if hasOpenAICreds, err := cm.HasOpenAICredentials(); err != nil {
+		fmt.Printf("Error checking credentials: %v\n", err)
+	} else if hasOpenAICreds {
+		if creds, err := cm.GetOpenAICredentials(); err != nil {
+			fmt.Printf("Error reading credentials: %v\n", err)
+		} else {
+			authType := "API Key"
+			status := "✓ Authenticated"
+
+			if creds.Type == "oauth" {
+				authType = "OAuth (ChatGPT/Codex)"
+				if creds.IsExpired() {
+					status = "⚠️  Token expired (will refresh automatically)"
+				} else if creds.NeedsRefresh() {
+					status = "⚠️  Token expires soon (will refresh automatically)"
+				}
+			}
+
+			accountInfo := ""
+			if creds.Type == "oauth" && creds.AccountID != "" {
+				accountInfo = fmt.Sprintf(" [%s]", creds.AccountID)
+			}
+
+			fmt.Printf("%s (%s%s, stored %s)\n", status, authType, accountInfo, creds.CreatedAt.Format("2006-01-02 15:04:05"))
+		}
+	} else {
+		fmt.Println("✗ Not authenticated")
+		// Check if environment variable is set
+		if os.Getenv("OPENAI_API_KEY") != "" {
+			fmt.Println("  (OPENAI_API_KEY environment variable is set)")
+		}
+	}
+
 	fmt.Println("\nTo authenticate with a provider:")
 	fmt.Println("  kit auth login anthropic")
+	fmt.Println("  kit auth login openai")
 
 	return nil
 }
@@ -282,3 +332,246 @@ func logoutAnthropic() error {
 
 	return nil
 }
+
+func loginOpenAI() error {
+	cm, err := kit.NewCredentialManager()
+	if err != nil {
+		return fmt.Errorf("failed to initialize credential manager: %w", err)
+	}
+
+	// Check if already authenticated
+	if hasAuth, err := cm.HasOpenAICredentials(); err == nil && hasAuth {
+		var reauth bool
+		err := huh.NewConfirm().
+			Title("You are already authenticated with OpenAI (ChatGPT/Codex)").
+			Description("Do you want to re-authenticate?").
+			Affirmative("Yes").
+			Negative("No").
+			Value(&reauth).
+			Run()
+		if err != nil || !reauth {
+			fmt.Println("Authentication cancelled.")
+			return nil
+		}
+	}
+
+	// Create OAuth client
+	client := auth.NewOpenAIOAuthClient()
+
+	// Generate authorization URL
+	fmt.Println("🔐 Starting OAuth authentication with OpenAI (ChatGPT/Codex)...")
+	fmt.Println("This will open your browser to authenticate with your ChatGPT account.")
+	fmt.Println()
+
+	authData, err := client.GetAuthorizationURL()
+	if err != nil {
+		return fmt.Errorf("failed to generate authorization URL: %w", err)
+	}
+
+	// Start local callback server
+	callbackServer, err := startOpenAICallbackServer(authData.State)
+	if err != nil {
+		fmt.Printf("⚠️  Could not start local callback server: %v\n", err)
+		fmt.Println("Falling back to manual code entry.")
+	}
+	if callbackServer != nil {
+		defer callbackServer.Close()
+	}
+
+	// Display URL and try to open browser
+	fmt.Println("📱 Opening your browser for authentication...")
+	fmt.Println("If the browser doesn't open automatically, please visit this URL:")
+	fmt.Printf("\n%s\n\n", authData.URL)
+
+	// Try to open browser
+	auth.TryOpenBrowser(authData.URL)
+
+	// Wait for callback or manual input
+	var code string
+	if callbackServer != nil {
+		fmt.Println("Waiting for browser authentication...")
+		select {
+		case callbackCode := <-callbackServer.CodeChan:
+			if callbackCode != "" {
+				code = callbackCode
+				fmt.Println("✓ Received authorization code from browser callback.")
+			}
+		case <-time.After(2 * time.Minute):
+			fmt.Println("\n⏱️  Timeout waiting for browser callback.")
+			callbackServer.Close()
+		}
+	}
+
+	// If no code from callback, prompt for manual entry
+	if code == "" {
+		fmt.Println("\nAfter authorizing, paste the callback URL or authorization code below.")
+		fmt.Println("(The callback URL will look like: http://localhost:1455/auth/callback?code=...&state=...)")
+		fmt.Println()
+
+		var input string
+		err = huh.NewInput().
+			Title("Callback URL or Code").
+			Description("Paste the full callback URL or just the authorization code").
+			Value(&input).
+			Run()
+		if err != nil {
+			return fmt.Errorf("failed to read input: %w", err)
+		}
+		input = strings.TrimSpace(input)
+
+		if input == "" {
+			return fmt.Errorf("authorization code cannot be empty")
+		}
+
+		// Parse the input (could be full URL or just code)
+		parsedCode, parsedState := auth.ParseOpenAIAuthorizationInput(input)
+		if parsedCode == "" {
+			return fmt.Errorf("could not extract authorization code from input")
+		}
+
+		// Validate state if provided
+		if parsedState != "" && parsedState != authData.State {
+			return fmt.Errorf("state mismatch - possible security issue")
+		}
+		code = parsedCode
+	}
+
+	// Exchange code for tokens
+	fmt.Println("\n🔄 Exchanging authorization code for access token...")
+	creds, err := client.ExchangeCode(code, authData.Verifier)
+	if err != nil {
+		return fmt.Errorf("failed to exchange authorization code: %w", err)
+	}
+
+	// Store the credentials
+	if err := cm.SetOpenAIOAuthCredentials(creds); err != nil {
+		return fmt.Errorf("failed to store credentials: %w", err)
+	}
+
+	fmt.Println("✅ Successfully authenticated with OpenAI (ChatGPT/Codex)!")
+	fmt.Printf("📁 Credentials stored in: %s\n", cm.GetCredentialsPath())
+	fmt.Printf("👤 Account ID: %s\n", creds.AccountID)
+	fmt.Println("\n🎉 Your OAuth credentials will now be used for OpenAI API calls.")
+	fmt.Println("💡 You can check your authentication status with: kit auth status")
+
+	return nil
+}
+
+// callbackServer holds the HTTP server and channel for receiving the OAuth callback
+type callbackServer struct {
+	Server   *http.Server
+	CodeChan chan string
+	State    string
+}
+
+// Close shuts down the callback server
+func (cs *callbackServer) Close() {
+	if cs.Server != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		_ = cs.Server.Shutdown(ctx)
+	}
+}
+
+// startOpenAICallbackServer starts a local HTTP server to receive the OAuth callback
+func startOpenAICallbackServer(expectedState string) (*callbackServer, error) {
+	codeChan := make(chan string, 1)
+
+	mux := http.NewServeMux()
+	server := &http.Server{
+		Addr:    "127.0.0.1:1455",
+		Handler: mux,
+	}
+
+	mux.HandleFunc("/auth/callback", func(w http.ResponseWriter, r *http.Request) {
+		// Check state
+		state := r.URL.Query().Get("state")
+		if state != expectedState {
+			http.Error(w, "State mismatch", http.StatusBadRequest)
+			return
+		}
+
+		code := r.URL.Query().Get("code")
+		if code == "" {
+			http.Error(w, "Missing authorization code", http.StatusBadRequest)
+			return
+		}
+
+		// Send code to channel
+		select {
+		case codeChan <- code:
+		default:
+		}
+
+		// Return success page
+		w.Header().Set("Content-Type", "text/html")
+		w.WriteHeader(http.StatusOK)
+		_, _ = fmt.Fprintf(w, `<!DOCTYPE html>
+<html>
+<head><title>Authentication Successful</title></head>
+<body style="font-family: sans-serif; text-align: center; padding: 50px;">
+<h1>✓ Authentication Successful</h1>
+<p>You can close this window and return to the terminal.</p>
+</body>
+</html>`)
+	})
+
+	// Try to start server
+	listener, err := net.Listen("tcp", "127.0.0.1:1455")
+	if err != nil {
+		return nil, fmt.Errorf("port 1455 not available: %w", err)
+	}
+	_ = listener.Close()
+
+	go func() {
+		_ = server.ListenAndServe()
+	}()
+
+	return &callbackServer{
+		Server:   server,
+		CodeChan: codeChan,
+		State:    expectedState,
+	}, nil
+}
+
+func logoutOpenAI() error {
+	cm, err := kit.NewCredentialManager()
+	if err != nil {
+		return fmt.Errorf("failed to initialize credential manager: %w", err)
+	}
+
+	// Check if authenticated
+	hasAuth, err := cm.HasOpenAICredentials()
+	if err != nil {
+		return fmt.Errorf("failed to check authentication status: %w", err)
+	}
+
+	if !hasAuth {
+		fmt.Println("You are not currently authenticated with OpenAI.")
+		return nil
+	}
+
+	// Confirm logout
+	var confirm bool
+	err = huh.NewConfirm().
+		Title("Remove OpenAI credentials").
+		Description("Are you sure you want to remove your stored credentials?").
+		Affirmative("Yes").
+		Negative("No").
+		Value(&confirm).
+		Run()
+	if err != nil || !confirm {
+		fmt.Println("Logout cancelled.")
+		return nil
+	}
+
+	// Remove credentials
+	if err := cm.RemoveOpenAICredentials(); err != nil {
+		return fmt.Errorf("failed to remove credentials: %w", err)
+	}
+
+	fmt.Println("✓ Successfully logged out from OpenAI!")
+	fmt.Println("You will need to use environment variables or command-line flags for authentication.")
+
+	return nil
+}

cmd/models.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"sort"
 
+	"github.com/mark3labs/kit/internal/models"
 	kit "github.com/mark3labs/kit/pkg/kit"
 	"github.com/spf13/cobra"
 )
@@ -47,6 +48,9 @@ func runModels(_ *cobra.Command, args []string) error {
 }
 
 func printAllProviders(showAll bool) error {
+	// Reload the registry to pick up any custom models from config
+	models.ReloadGlobalRegistry()
+
 	var providerIDs []string
 	if showAll {
 		providerIDs = kit.GetSupportedProviders()
@@ -98,6 +102,9 @@ func printAllProviders(showAll bool) error {
 }
 
 func printProvider(provider string) error {
+	// Reload the registry to pick up any custom models from config
+	models.ReloadGlobalRegistry()
+
 	m, err := kit.GetModelsForProvider(provider)
 	if err != nil {
 		return fmt.Errorf("unknown provider %q. Run 'kit models' to see all providers", provider)

cmd/root.go

@@ -13,9 +13,11 @@ import (
 	"charm.land/fantasy"
 	"charm.land/lipgloss/v2"
 	"github.com/mark3labs/kit/internal/app"
+	"github.com/mark3labs/kit/internal/auth"
 	"github.com/mark3labs/kit/internal/config"
 	"github.com/mark3labs/kit/internal/extensions"
 	"github.com/mark3labs/kit/internal/models"
+	"github.com/mark3labs/kit/internal/prompts"
 	"github.com/mark3labs/kit/internal/ui"
 	kit "github.com/mark3labs/kit/pkg/kit"
 	"github.com/spf13/cobra"
@@ -65,6 +67,15 @@ var (
 
 	// TLS configuration
 	tlsSkipVerify bool
+
+	// Prompt templates
+	promptTemplatePaths []string
+	noPromptTemplates   bool
+
+	// Preference restoration flags — set in RunE after cobra parses, used
+	// in runNormalMode to decide whether to apply saved preferences.
+	modelFlagChanged    bool
+	thinkingFlagChanged bool
 )
 
 // kitUIAdapter adapts *kit.Kit to ui.AgentInterface so the CLI setup layer
@@ -113,6 +124,17 @@ var rootCmd = &cobra.Command{
 		if len(args) > 0 {
 			processPositionalArgs(args)
 		}
+		// Record whether --model / --thinking-level were explicitly set by the
+		// user so that runNormalMode can fall back to saved preferences when
+		// they weren't. Must be captured here (after cobra parses) and before
+		// runKit because rootCmd can't be referenced inside runNormalMode
+		// without creating an initialization cycle.
+		if f := cmd.PersistentFlags().Lookup("model"); f != nil {
+			modelFlagChanged = f.Changed
+		}
+		if f := cmd.PersistentFlags().Lookup("thinking-level"); f != nil {
+			thinkingFlagChanged = f.Changed
+		}
 		return runKit(context.Background())
 	},
 }
@@ -232,6 +254,9 @@ func init() {
 	if err == nil && viper.InConfig("theme") {
 		uiTheme := configToUiTheme(theme)
 		ui.SetTheme(uiTheme)
+	} else if pref := ui.LoadThemePreference(); pref != "" {
+		// No explicit theme in config — fall back to persisted preference.
+		_ = ui.ApplyThemeWithoutSave(pref)
 	}
 
 	rootCmd.PersistentFlags().
@@ -277,6 +302,10 @@ func init() {
 	flags.StringVar(&providerAPIKey, "provider-api-key", "", "API key for the provider (applies to OpenAI, Anthropic, and Google)")
 	flags.BoolVar(&tlsSkipVerify, "tls-skip-verify", false, "skip TLS certificate verification (WARNING: insecure, use only for self-signed certificates)")
 
+	// Prompt template flags
+	flags.StringArrayVar(&promptTemplatePaths, "prompt-template", nil, "load prompt template file or directory (repeatable)")
+	flags.BoolVar(&noPromptTemplates, "no-prompt-templates", false, "disable prompt template discovery")
+
 	// Model generation parameters
 	flags.IntVar(&maxTokens, "max-tokens", 4096, "maximum number of tokens in the response")
 	flags.Float32Var(&temperature, "temperature", 0.7, "controls randomness in responses (0.0-1.0)")
@@ -312,6 +341,8 @@ func init() {
 	_ = viper.BindPFlag("tls-skip-verify", rootCmd.PersistentFlags().Lookup("tls-skip-verify"))
 	_ = viper.BindPFlag("no-extensions", rootCmd.PersistentFlags().Lookup("no-extensions"))
 	_ = viper.BindPFlag("extension", rootCmd.PersistentFlags().Lookup("extension"))
+	_ = viper.BindPFlag("prompt-template", rootCmd.PersistentFlags().Lookup("prompt-template"))
+	_ = viper.BindPFlag("no-prompt-templates", rootCmd.PersistentFlags().Lookup("no-prompt-templates"))
 
 	// Defaults are already set in flag definitions, no need to duplicate in viper
 
@@ -643,6 +674,32 @@ func runNormalMode(ctx context.Context) error {
 		log.SetFlags(log.LstdFlags | log.Lshortfile)
 	}
 
+	// Restore persisted model preference when no explicit --model flag or
+	// config file model is set. Precedence: CLI flag > config file > saved
+	// preference > built-in default. This mirrors how themes are persisted.
+	if !modelFlagChanged && !viper.InConfig("model") {
+		if pref := ui.LoadModelPreference(); pref != "" {
+			viper.Set("model", pref)
+		}
+	}
+
+	// Restore persisted thinking level preference (same precedence chain).
+	if !thinkingFlagChanged && !viper.InConfig("thinking-level") {
+		if pref := ui.LoadThinkingLevelPreference(); pref != "" {
+			viper.Set("thinking-level", pref)
+		}
+	}
+
+	// When --provider-url is set but no explicit --model was provided,
+	// default to "custom/custom" so the user doesn't need to remember a
+	// provider/model pair for custom OpenAI-compatible endpoints.
+	// This intentionally overrides saved preferences but respects config-file
+	// models — if you specify a model in ~/.kit.yml, it will be used with
+	// custom/custom's provider routing.
+	if viper.GetString("provider-url") != "" && !modelFlagChanged && !viper.InConfig("model") {
+		viper.Set("model", "custom/custom")
+	}
+
 	// Load MCP configuration.
 	mcpConfig, err := config.LoadAndValidateConfig()
 	if err != nil {
@@ -678,11 +735,16 @@ func runNormalMode(ctx context.Context) error {
 		},
 	}
 	if resumeFlag {
-		// TODO: TUI session picker.
-		sessions, _ := kit.ListSessions("")
-		if len(sessions) > 0 {
-			kitOpts.SessionPath = sessions[0].Path
+		// When --resume is combined with interactive mode, the TUI session
+		// picker will be shown at startup. For non-interactive mode, fall
+		// back to auto-selecting the most recent session.
+		if positionalPrompt != "" {
+			sessions, _ := kit.ListSessions("")
+			if len(sessions) > 0 {
+				kitOpts.SessionPath = sessions[0].Path
+			}
 		}
+		// Interactive mode: ShowSessionPicker is set below on AppModelOptions.
 	}
 
 	kitInstance, err := kit.New(ctx, kitOpts)
@@ -749,7 +811,7 @@ func runNormalMode(ctx context.Context) error {
 			PrintError:    func(text string) { appInstance.PrintFromExtension("error", text) },
 			PrintBlock:    appInstance.PrintBlockFromExtension,
 			SendMessage:   func(text string) { appInstance.Run(text) },
-			CancelAndSend: func(text string) { appInstance.Steer(text) },
+			CancelAndSend: func(text string) { appInstance.InterruptAndSend(text) },
 			Exit:          func() { appInstance.QuitFromExtension() },
 			SetWidget: func(config extensions.WidgetConfig) {
 				kitInstance.SetExtensionWidget(config)
@@ -894,6 +956,24 @@ func runNormalMode(ctx context.Context) error {
 				kitInstance.UpdateExtensionContextModel(modelString)
 				// Fire OnModelChange event to extensions.
 				kitInstance.EmitModelChange(modelString, previousModel, "extension")
+				// Update usage tracker with new model info for correct token counting.
+				if usageTracker != nil {
+					newProvider, newModel, _ := models.ParseModelString(modelString)
+					if newProvider != "unknown" && newModel != "unknown" && newProvider != "ollama" {
+						registry := models.GetGlobalRegistry()
+						if modelInfo := registry.LookupModel(newProvider, newModel); modelInfo != nil {
+							// Check OAuth status for Anthropic models
+							isOAuth := false
+							if newProvider == "anthropic" {
+								_, source, err := auth.GetAnthropicAPIKey(viper.GetString("provider-api-key"))
+								if err == nil && strings.HasPrefix(source, "stored OAuth") {
+									isOAuth = true
+								}
+							}
+							usageTracker.UpdateModelInfo(modelInfo, newProvider, isOAuth)
+						}
+					}
+				}
 				return nil
 			},
 			GetAvailableModels: func() []extensions.ModelInfoEntry {
@@ -1024,6 +1104,27 @@ func runNormalMode(ctx context.Context) error {
 	// Convert extension commands to UI-layer type for the interactive TUI.
 	extCommands := extensionCommandsForUI(kitInstance)
 
+	// Load prompt templates from standard locations and explicit paths.
+	var promptTemplates []*prompts.PromptTemplate
+	if !noPromptTemplates {
+		homeDir, _ := os.UserHomeDir()
+		cwd, _ := os.Getwd()
+		tpls, diags, err := prompts.LoadAll(prompts.LoadOptions{
+			Cwd:             cwd,
+			HomeDir:         homeDir,
+			ExtraPaths:      promptTemplatePaths,
+			ConfigPaths:     viper.GetStringSlice("prompts"),
+			IncludeDefaults: true,
+		})
+		if err != nil {
+			log.Printf("Warning: failed to load some prompt templates: %v", err)
+		}
+		promptTemplates = tpls
+		for _, d := range diags {
+			log.Printf("Prompt template collision: /%s kept from %s, dropped from %s", d.Name, d.KeptPath, d.DroppedPath)
+		}
+	}
+
 	// Build context/skills display metadata for the startup banner.
 	var contextPaths []string
 	for _, cf := range kitInstance.GetContextFiles() {
@@ -1070,6 +1171,24 @@ func runNormalMode(ctx context.Context) error {
 		// this callback runs synchronously inside BubbleTea's Update(), and
 		// NotifyModelChanged calls prog.Send() which deadlocks. The UI layer
 		// updates m.providerName and m.modelName directly after setModel returns.
+		// Update usage tracker with new model info for correct token counting.
+		if usageTracker != nil {
+			newProvider, newModel, _ := models.ParseModelString(modelString)
+			if newProvider != "unknown" && newModel != "unknown" && newProvider != "ollama" {
+				registry := models.GetGlobalRegistry()
+				if modelInfo := registry.LookupModel(newProvider, newModel); modelInfo != nil {
+					// Check OAuth status for Anthropic models
+					isOAuth := false
+					if newProvider == "anthropic" {
+						_, source, err := auth.GetAnthropicAPIKey(viper.GetString("provider-api-key"))
+						if err == nil && strings.HasPrefix(source, "stored OAuth") {
+							isOAuth = true
+						}
+					}
+					usageTracker.UpdateModelInfo(modelInfo, newProvider, isOAuth)
+				}
+			}
+		}
 		return nil
 	}
 	emitModelChangeForUI := func(newModel, previousModel, source string) {
@@ -1081,9 +1200,21 @@ func runNormalMode(ctx context.Context) error {
 		return kitInstance.SetThinkingLevel(context.Background(), level)
 	}
 
+	// Build session-switching callback. Opens a JSONL session file and
+	// replaces the active tree session on both the Kit SDK and App layer.
+	switchSessionForUI := func(path string) error {
+		ts, err := kit.OpenTreeSession(path)
+		if err != nil {
+			return fmt.Errorf("failed to open session: %w", err)
+		}
+		kitInstance.SetTreeSession(ts)
+		appInstance.SwitchTreeSession(ts)
+		return nil
+	}
+
 	// Check if running in non-interactive mode
 	if positionalPrompt != "" {
-		return runNonInteractiveModeApp(ctx, appInstance, cli, positionalPrompt, quietFlag, jsonFlag, noExitFlag, modelName, parsedProvider, kitInstance.GetLoadingMessage(), serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModelForUI, emitModelChangeForUI, kitInstance.IsReasoningModel(), kitInstance.GetThinkingLevel(), setThinkingLevelForUI)
+		return runNonInteractiveModeApp(ctx, appInstance, cli, positionalPrompt, quietFlag, jsonFlag, noExitFlag, modelName, parsedProvider, kitInstance.GetLoadingMessage(), serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, promptTemplates, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModelForUI, emitModelChangeForUI, kitInstance.IsReasoningModel(), kitInstance.GetThinkingLevel(), setThinkingLevelForUI, switchSessionForUI)
 	}
 
 	// Quiet mode is not allowed in interactive mode
@@ -1091,7 +1222,7 @@ func runNormalMode(ctx context.Context) error {
 		return fmt.Errorf("--quiet requires a prompt")
 	}
 
-	return runInteractiveModeBubbleTea(ctx, appInstance, modelName, parsedProvider, kitInstance.GetLoadingMessage(), serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModelForUI, emitModelChangeForUI, kitInstance.IsReasoningModel(), kitInstance.GetThinkingLevel(), setThinkingLevelForUI)
+	return runInteractiveModeBubbleTea(ctx, appInstance, modelName, parsedProvider, kitInstance.GetLoadingMessage(), serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, promptTemplates, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModelForUI, emitModelChangeForUI, kitInstance.IsReasoningModel(), kitInstance.GetThinkingLevel(), setThinkingLevelForUI, switchSessionForUI)
 }
 
 // runNonInteractiveModeApp executes a single prompt via the app layer and exits,
@@ -1104,7 +1235,7 @@ func runNormalMode(ctx context.Context) error {
 //
 // When --no-exit is set, after the prompt completes the interactive BubbleTea
 // TUI is started so the user can continue the conversation.
-func runNonInteractiveModeApp(ctx context.Context, appInstance *app.App, cli *ui.CLI, prompt string, quiet, jsonOutput, noExit bool, modelName, providerName, loadingMessage string, serverNames, toolNames []string, mcpToolCount, extensionToolCount int, usageTracker *ui.UsageTracker, extCommands []ui.ExtensionCommand, contextPaths []string, skillItems []ui.SkillItem, getWidgets func(string) []ui.WidgetData, getHeader, getFooter func() *ui.WidgetData, getToolRenderer func(string) *ui.ToolRendererData, getEditorInterceptor func() *ui.EditorInterceptor, getUIVisibility func() *ui.UIVisibility, getStatusBarEntries func() []ui.StatusBarEntryData, emitBeforeFork func(string, bool, string) (bool, string), emitBeforeSessionSwitch func(string) (bool, string), getGlobalShortcuts func() map[string]func(), getExtensionCommands func() []ui.ExtensionCommand, setModel func(string) error, emitModelChange func(string, string, string), isReasoningModel bool, thinkingLevel string, setThinkingLevel func(string) error) error {
+func runNonInteractiveModeApp(ctx context.Context, appInstance *app.App, cli *ui.CLI, prompt string, quiet, jsonOutput, noExit bool, modelName, providerName, loadingMessage string, serverNames, toolNames []string, mcpToolCount, extensionToolCount int, usageTracker *ui.UsageTracker, extCommands []ui.ExtensionCommand, promptTemplates []*prompts.PromptTemplate, contextPaths []string, skillItems []ui.SkillItem, getWidgets func(string) []ui.WidgetData, getHeader, getFooter func() *ui.WidgetData, getToolRenderer func(string) *ui.ToolRendererData, getEditorInterceptor func() *ui.EditorInterceptor, getUIVisibility func() *ui.UIVisibility, getStatusBarEntries func() []ui.StatusBarEntryData, emitBeforeFork func(string, bool, string) (bool, string), emitBeforeSessionSwitch func(string) (bool, string), getGlobalShortcuts func() map[string]func(), getExtensionCommands func() []ui.ExtensionCommand, setModel func(string) error, emitModelChange func(string, string, string), isReasoningModel bool, thinkingLevel string, setThinkingLevel func(string) error, switchSession func(string) error) error {
 	// Expand @file references in the prompt before sending to the agent.
 	if cwd, err := os.Getwd(); err == nil {
 		prompt = ui.ProcessFileAttachments(prompt, cwd)
@@ -1147,7 +1278,7 @@ func runNonInteractiveModeApp(ctx context.Context, appInstance *app.App, cli *ui
 
 	// If --no-exit was requested, hand off to the interactive TUI.
 	if noExit {
-		return runInteractiveModeBubbleTea(ctx, appInstance, modelName, providerName, loadingMessage, serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModel, emitModelChange, isReasoningModel, thinkingLevel, setThinkingLevel)
+		return runInteractiveModeBubbleTea(ctx, appInstance, modelName, providerName, loadingMessage, serverNames, toolNames, mcpToolCount, extensionToolCount, usageTracker, extCommands, promptTemplates, contextPaths, skillItems, getWidgets, getHeader, getFooter, getToolRenderer, getEditorInterceptor, getUIVisibility, getStatusBarEntries, emitBeforeFork, emitBeforeSessionSwitch, getGlobalShortcuts, getExtensionCommands, setModel, emitModelChange, isReasoningModel, thinkingLevel, setThinkingLevel, switchSession)
 	}
 
 	return nil
@@ -1245,7 +1376,7 @@ func writeJSONError(err error) {
 //  4. Calls program.Run() which blocks until the user quits (Ctrl+C or /quit).
 //
 // SetupCLI is not used for interactive mode; the TUI (AppModel) handles its own rendering.
-func runInteractiveModeBubbleTea(_ context.Context, appInstance *app.App, modelName, providerName, loadingMessage string, serverNames, toolNames []string, mcpToolCount, extensionToolCount int, usageTracker *ui.UsageTracker, extCommands []ui.ExtensionCommand, contextPaths []string, skillItems []ui.SkillItem, getWidgets func(string) []ui.WidgetData, getHeader, getFooter func() *ui.WidgetData, getToolRenderer func(string) *ui.ToolRendererData, getEditorInterceptor func() *ui.EditorInterceptor, getUIVisibility func() *ui.UIVisibility, getStatusBarEntries func() []ui.StatusBarEntryData, emitBeforeFork func(string, bool, string) (bool, string), emitBeforeSessionSwitch func(string) (bool, string), getGlobalShortcuts func() map[string]func(), getExtensionCommands func() []ui.ExtensionCommand, setModel func(string) error, emitModelChange func(string, string, string), isReasoningModel bool, thinkingLevel string, setThinkingLevel func(string) error) error {
+func runInteractiveModeBubbleTea(_ context.Context, appInstance *app.App, modelName, providerName, loadingMessage string, serverNames, toolNames []string, mcpToolCount, extensionToolCount int, usageTracker *ui.UsageTracker, extCommands []ui.ExtensionCommand, promptTemplates []*prompts.PromptTemplate, contextPaths []string, skillItems []ui.SkillItem, getWidgets func(string) []ui.WidgetData, getHeader, getFooter func() *ui.WidgetData, getToolRenderer func(string) *ui.ToolRendererData, getEditorInterceptor func() *ui.EditorInterceptor, getUIVisibility func() *ui.UIVisibility, getStatusBarEntries func() []ui.StatusBarEntryData, emitBeforeFork func(string, bool, string) (bool, string), emitBeforeSessionSwitch func(string) (bool, string), getGlobalShortcuts func() map[string]func(), getExtensionCommands func() []ui.ExtensionCommand, setModel func(string) error, emitModelChange func(string, string, string), isReasoningModel bool, thinkingLevel string, setThinkingLevel func(string) error, switchSession func(string) error) error {
 	// Determine terminal size; fall back gracefully.
 	termWidth, termHeight, err := term.GetSize(int(os.Stdout.Fd()))
 	if err != nil || termWidth == 0 {
@@ -1254,6 +1385,7 @@ func runInteractiveModeBubbleTea(_ context.Context, appInstance *app.App, modelN
 	}
 
 	cwd, _ := os.Getwd()
+
 	appModel := ui.NewAppModel(appInstance, ui.AppModelOptions{
 		CompactMode:             viper.GetBool("compact"),
 		ModelName:               modelName,
@@ -1268,6 +1400,7 @@ func runInteractiveModeBubbleTea(_ context.Context, appInstance *app.App, modelN
 		ExtensionToolCount:      extensionToolCount,
 		UsageTracker:            usageTracker,
 		ExtensionCommands:       extCommands,
+		PromptTemplates:         promptTemplates,
 		ContextPaths:            contextPaths,
 		SkillItems:              skillItems,
 		GetWidgets:              getWidgets,
@@ -1286,6 +1419,8 @@ func runInteractiveModeBubbleTea(_ context.Context, appInstance *app.App, modelN
 		ThinkingLevel:           thinkingLevel,
 		IsReasoningModel:        isReasoningModel,
 		SetThinkingLevel:        setThinkingLevel,
+		SwitchSession:           switchSession,
+		ShowSessionPicker:       resumeFlag,
 	})
 
 	// Print startup info to stdout before Bubble Tea takes over the screen.

cmd/skill.go

@@ -8,19 +8,21 @@ import (
 	"github.com/spf13/cobra"
 )
 
-// skillCmd installs the kit-extensions skill via the skills.sh CLI (npx skills).
-// This teaches AI agents how to create Kit extensions with full knowledge of
-// the extension API, lifecycle events, widgets, tools, commands, and Yaegi constraints.
+// skillCmd installs Kit skills via the skills.sh CLI (npx skills).
 var skillCmd = &cobra.Command{
 	Use:   "skill",
-	Short: "Install the Kit extensions skill via skills.sh",
-	Long: `Install the kit-extensions skill that teaches AI agents how to create
-Kit extensions. Uses the skills.sh CLI (npx skills) to install the skill
-from the Kit repository.
+	Short: "Install Kit skills via skills.sh",
+	Long: `Install Kit skills that teach AI agents how to build with Kit.
+Uses the skills.sh CLI (npx skills) to install all skills from the Kit repository.
 
-The skill provides comprehensive documentation of Kit's extension API including
-lifecycle events, custom tools, slash commands, widgets, editor interceptors,
-tool renderers, and critical Yaegi interpreter constraints.
+Two skills are provided:
+
+  1. Extensions — creating Kit extensions with full knowledge of the extension
+     API, lifecycle events, widgets, tools, commands, editor interceptors,
+     tool renderers, and Yaegi interpreter constraints.
+
+  2. SDK — building AI-powered applications with the Kit Go SDK, including
+     providers, agents, tools, and MCP integration.
 
 Example:
   kit skill`,
@@ -41,8 +43,6 @@ func runSkill(_ *cobra.Command, _ []string) error {
 		"skills",
 		"add",
 		"mark3labs/kit",
-		"--skill",
-		"kit-extensions",
 	}
 
 	cmd := exec.Command(npx, args...)

examples/extensions/subagent-monitor_test.go

@@ -0,0 +1,159 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/mark3labs/kit/internal/extensions"
+	"github.com/mark3labs/kit/pkg/extensions/test"
+)
+
+// TestSubagentMonitor_SessionStart verifies OnSessionStart initializes state
+// without panicking and properly guards nil ctx calls.
+func TestSubagentMonitor_SessionStart(t *testing.T) {
+	harness := test.New(t)
+	harness.LoadFile("../../.kit/extensions/subagent-monitor.go")
+
+	// Emit SessionStart - should not panic even with nil ctx functions
+	_, err := harness.Emit(extensions.SessionStartEvent{SessionID: "test-session"})
+	if err != nil {
+		t.Fatalf("SessionStart should not error: %v", err)
+	}
+}
+
+// TestSubagentMonitor_SubagentLifecycle verifies the full subagent lifecycle
+// creates entries and emits widget updates.
+func TestSubagentMonitor_SubagentLifecycle(t *testing.T) {
+	harness := test.New(t)
+	harness.LoadFile("../../.kit/extensions/subagent-monitor.go")
+
+	// Start session
+	_, err := harness.Emit(extensions.SessionStartEvent{SessionID: "test-session"})
+	if err != nil {
+		t.Fatalf("SessionStart should not error: %v", err)
+	}
+
+	// Emit SubagentStart
+	_, err = harness.Emit(extensions.SubagentStartEvent{
+		ToolCallID: "call-1",
+		Task:       "test task",
+	})
+	if err != nil {
+		t.Fatalf("SubagentStart should not error: %v", err)
+	}
+
+	// Emit a few chunks
+	for i := range 3 {
+		_, err = harness.Emit(extensions.SubagentChunkEvent{
+			ToolCallID: "call-1",
+			Task:       "test task",
+			ChunkType:  "text",
+			Content:    fmt.Sprintf("line %d", i),
+		})
+		if err != nil {
+			t.Fatalf("SubagentChunk %d should not error: %v", i, err)
+		}
+	}
+
+	// Emit tool call chunk
+	_, err = harness.Emit(extensions.SubagentChunkEvent{
+		ToolCallID: "call-1",
+		Task:       "test task",
+		ChunkType:  "tool_call",
+		ToolName:   "bash",
+	})
+	if err != nil {
+		t.Fatalf("SubagentChunk tool_call should not error: %v", err)
+	}
+
+	// Emit SubagentEnd
+	_, err = harness.Emit(extensions.SubagentEndEvent{
+		ToolCallID: "call-1",
+		Task:       "test task",
+		Response:   "done",
+	})
+	if err != nil {
+		t.Fatalf("SubagentEnd should not error: %v", err)
+	}
+
+	// Give time for cleanup goroutine
+	time.Sleep(100 * time.Millisecond)
+}
+
+// TestSubagentMonitor_MultipleSubagents verifies multiple parallel subagents.
+func TestSubagentMonitor_MultipleSubagents(t *testing.T) {
+	harness := test.New(t)
+	harness.LoadFile("../../.kit/extensions/subagent-monitor.go")
+
+	_, err := harness.Emit(extensions.SessionStartEvent{SessionID: "test-session"})
+	if err != nil {
+		t.Fatalf("SessionStart should not error: %v", err)
+	}
+
+	// Start 3 subagents
+	for i := 1; i <= 3; i++ {
+		_, err := harness.Emit(extensions.SubagentStartEvent{
+			ToolCallID: fmt.Sprintf("call-%d", i),
+			Task:       fmt.Sprintf("task %d", i),
+		})
+		if err != nil {
+			t.Fatalf("SubagentStart %d should not error: %v", i, err)
+		}
+	}
+
+	// Emit chunks for each
+	for i := 1; i <= 3; i++ {
+		_, err := harness.Emit(extensions.SubagentChunkEvent{
+			ToolCallID: fmt.Sprintf("call-%d", i),
+			Task:       fmt.Sprintf("task %d", i),
+			ChunkType:  "text",
+			Content:    fmt.Sprintf("output from agent %d", i),
+		})
+		if err != nil {
+			t.Fatalf("SubagentChunk %d should not error: %v", i, err)
+		}
+	}
+
+	// End all subagents
+	for i := 1; i <= 3; i++ {
+		_, err := harness.Emit(extensions.SubagentEndEvent{
+			ToolCallID: fmt.Sprintf("call-%d", i),
+			Task:       fmt.Sprintf("task %d", i),
+			Response:   "completed",
+		})
+		if err != nil {
+			t.Fatalf("SubagentEnd %d should not error: %v", i, err)
+		}
+	}
+
+	time.Sleep(100 * time.Millisecond)
+}
+
+// TestSubagentMonitor_SessionShutdown verifies shutdown doesn't panic
+// even with nil ctx functions.
+func TestSubagentMonitor_SessionShutdown(t *testing.T) {
+	harness := test.New(t)
+	harness.LoadFile("../../.kit/extensions/subagent-monitor.go")
+
+	// Start then shutdown
+	_, err := harness.Emit(extensions.SessionStartEvent{SessionID: "test-session"})
+	if err != nil {
+		t.Fatalf("SessionStart should not error: %v", err)
+	}
+
+	// Start a subagent
+	_, err = harness.Emit(extensions.SubagentStartEvent{
+		ToolCallID: "call-1",
+		Task:       "test task",
+	})
+	if err != nil {
+		t.Fatalf("SubagentStart should not error: %v", err)
+	}
+
+	// Shutdown - should not panic even with active subagent
+	_, err = harness.Emit(extensions.SessionShutdownEvent{})
+	if err != nil {
+		t.Fatalf("SessionShutdown should not error: %v", err)
+	}
+}

examples/sdk/README.md

@@ -0,0 +1,45 @@
+# SDK Examples
+
+These examples demonstrate how to use the Kit SDK (`pkg/kit`) to build agents programmatically in Go.
+
+## Examples
+
+### [basic](basic/)
+
+Shows core SDK usage: creating a Kit instance, sending prompts, overriding the model, subscribing to events (tool calls, streaming), and session management.
+
+```bash
+go run ./examples/sdk/basic
+```
+
+### [scripting](scripting/)
+
+A minimal script-friendly wrapper that takes a prompt from the command line and prints the response — useful for piping and automation.
+
+```bash
+go run ./examples/sdk/scripting "Explain what this repo does"
+```
+
+### [crypto-monitor](crypto-monitor/)
+
+A background agent that checks Bitcoin and Ethereum prices every 30 minutes and sends desktop notifications via `notify-send` (dbus). Demonstrates using the SDK for a long-running autonomous task with a single tool.
+
+```bash
+go run ./examples/sdk/crypto-monitor
+
+# Override the check interval:
+CRYPTO_INTERVAL=5m go run ./examples/sdk/crypto-monitor
+```
+
+## Getting Started
+
+```go
+import kit "github.com/mark3labs/kit/pkg/kit"
+
+host, err := kit.New(ctx, nil)        // uses ~/.kit.yml defaults
+defer host.Close()
+
+response, err := host.Prompt(ctx, "Hello!")
+```
+
+See the [SDK README](../../pkg/kit/README.md) for the full API reference.

examples/sdk/crypto-monitor/main.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"time"
+
+	kit "github.com/mark3labs/kit/pkg/kit"
+)
+
+const systemPrompt = `You are a cryptocurrency price monitor. Your job is to:
+
+1. Fetch the current prices of Bitcoin and Ethereum using bash with curl
+2. Send a desktop notification with the results using notify-send
+
+To fetch prices, use this CoinGecko API endpoint (no API key needed):
+  curl -s 'https://api.coingecko.com/api/v3/simple/price?ids=bitcoin,ethereum&vs_currencies=usd&include_24hr_change=true'
+
+To send a desktop notification:
+  notify-send -i dialog-information "Crypto Prices" "BTC: $XX,XXX (+X.X%)\nETH: $X,XXX (+X.X%)"
+
+Include the 24h percentage change in the notification. Use a green arrow (▲) for
+positive changes and a red arrow (▼) for negative. Format prices with commas.
+
+If the API call fails, send a notification about the failure instead.
+
+Always complete both steps: fetch then notify. Be concise — no commentary needed.`
+
+func main() {
+	interval := 30 * time.Minute
+	if os.Getenv("CRYPTO_INTERVAL") != "" {
+		d, err := time.ParseDuration(os.Getenv("CRYPTO_INTERVAL"))
+		if err == nil {
+			interval = d
+		}
+	}
+
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer cancel()
+
+	host, err := kit.New(ctx, &kit.Options{
+		SystemPrompt: systemPrompt,
+		Tools:        []kit.Tool{kit.NewBashTool()},
+		NoSession:    true,
+		Quiet:        true,
+	})
+	if err != nil {
+		log.Fatalf("Failed to create kit instance: %v", err)
+	}
+	defer func() { _ = host.Close() }()
+
+	fmt.Printf("Crypto price monitor started (every %s)\n", interval)
+	fmt.Println("Press Ctrl+C to stop")
+
+	// Run immediately on startup, then on each tick.
+	check(ctx, host)
+
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			check(ctx, host)
+		case <-ctx.Done():
+			fmt.Println("\nStopping price monitor")
+			return
+		}
+	}
+}
+
+func check(ctx context.Context, host *kit.Kit) {
+	fmt.Printf("[%s] Checking prices...\n", time.Now().Format("15:04:05"))
+
+	// Clear session so each check is independent.
+	host.ClearSession()
+
+	_, err := host.Prompt(ctx, "Fetch current Bitcoin and Ethereum prices and send a desktop notification.")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+	}
+}

go.mod

@@ -1,69 +1,68 @@
 module github.com/mark3labs/kit
 
-go 1.26.0
+go 1.26.1
 
 require (
 	charm.land/bubbles/v2 v2.0.0
 	charm.land/bubbletea/v2 v2.0.2
-	charm.land/fantasy v0.11.1
-	charm.land/lipgloss/v2 v2.0.1
+	charm.land/fantasy v0.17.1
+	charm.land/huh/v2 v2.0.3
+	charm.land/lipgloss/v2 v2.0.2
 	github.com/alecthomas/chroma/v2 v2.23.1
 	github.com/aymanbagabas/go-udiff v0.4.1
-	github.com/charmbracelet/fang v0.4.4
-	github.com/charmbracelet/log v0.4.2
-	github.com/mark3labs/mcp-go v0.44.1
+	github.com/charmbracelet/fang v1.0.0
+	github.com/charmbracelet/log v1.0.0
+	github.com/coder/acp-go-sdk v0.6.3
+	github.com/mark3labs/mcp-go v0.46.0
 	github.com/spf13/cobra v1.10.2
 	github.com/spf13/viper v1.21.0
 	github.com/traefik/yaegi v0.16.1
-	golang.org/x/term v0.40.0
+	golang.org/x/term v0.41.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
-	charm.land/huh/v2 v2.0.3 // indirect
 	cloud.google.com/go v0.123.0 // indirect
-	cloud.google.com/go/auth v0.18.2 // indirect
+	cloud.google.com/go/auth v0.19.0 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
 	cloud.google.com/go/compute/metadata v0.9.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.21.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 // indirect
 	github.com/atotto/clipboard v0.1.4 // indirect
-	github.com/aws/aws-sdk-go-v2 v1.41.3 // indirect
-	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.6 // indirect
-	github.com/aws/aws-sdk-go-v2/config v1.32.11 // indirect
-	github.com/aws/aws-sdk-go-v2/credentials v1.19.11 // indirect
-	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.19 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.19 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.19 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.5 // indirect
-	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.6 // indirect
-	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.19 // indirect
-	github.com/aws/aws-sdk-go-v2/service/signin v1.0.7 // indirect
-	github.com/aws/aws-sdk-go-v2/service/sso v1.30.12 // indirect
-	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.16 // indirect
-	github.com/aws/aws-sdk-go-v2/service/sts v1.41.8 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.41.4 // indirect
+	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8 // indirect
+	github.com/aws/aws-sdk-go-v2/config v1.32.12 // indirect
+	github.com/aws/aws-sdk-go-v2/credentials v1.19.12 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.6 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.7 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.20 // indirect
+	github.com/aws/aws-sdk-go-v2/service/signin v1.0.8 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.30.13 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.17 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.41.9 // indirect
 	github.com/aws/smithy-go v1.24.2 // indirect
 	github.com/aymerick/douceur v0.2.0 // indirect
-	github.com/bahlo/generic-list-go v0.2.0 // indirect
-	github.com/buger/jsonparser v1.1.1 // indirect
-	github.com/catppuccin/go v0.2.0 // indirect
+	github.com/catppuccin/go v0.3.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/charmbracelet/anthropic-sdk-go v0.0.0-20260223140439-63879b0b8dab // indirect
-	github.com/charmbracelet/colorprofile v0.4.2 // indirect
+	github.com/charmbracelet/colorprofile v0.4.3 // indirect
 	github.com/charmbracelet/harmonica v0.2.0 // indirect
 	github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834 // indirect
-	github.com/charmbracelet/ultraviolet v0.0.0-20260303162955-0b88c25f3fff // indirect
+	github.com/charmbracelet/openai-go v0.0.0-20260319145158-d0740cc34266 // indirect
+	github.com/charmbracelet/ultraviolet v0.0.0-20260316091819-b93f6a3b8502 // indirect
 	github.com/charmbracelet/x/cellbuf v0.0.15 // indirect
-	github.com/charmbracelet/x/exp/charmtone v0.0.0-20260305213658-fe36e8c10185 // indirect
+	github.com/charmbracelet/x/exp/charmtone v0.0.0-20260323091123-df7b1bcffcca // indirect
 	github.com/charmbracelet/x/exp/ordered v0.1.0 // indirect
-	github.com/charmbracelet/x/exp/slice v0.0.0-20260305213658-fe36e8c10185 // indirect
-	github.com/charmbracelet/x/exp/strings v0.0.0-20240722160745-212f7b056ed0 // indirect
+	github.com/charmbracelet/x/exp/slice v0.0.0-20260323091123-df7b1bcffcca // indirect
+	github.com/charmbracelet/x/exp/strings v0.1.0 // indirect
 	github.com/charmbracelet/x/json v0.2.0 // indirect
 	github.com/charmbracelet/x/termios v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.2.2 // indirect
 	github.com/clipperhouse/displaywidth v0.11.0 // indirect
 	github.com/clipperhouse/uax29/v2 v2.7.0 // indirect
-	github.com/coder/acp-go-sdk v0.6.3 // indirect
 	github.com/dlclark/regexp2 v1.11.5 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
@@ -76,18 +75,17 @@ require (
 	github.com/goccy/go-yaml v1.19.2 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/google/jsonschema-go v0.4.2 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.14 // indirect
-	github.com/googleapis/gax-go/v2 v2.17.0 // indirect
+	github.com/googleapis/gax-go/v2 v2.20.0 // indirect
 	github.com/gorilla/css v1.0.1 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
-	github.com/invopop/jsonschema v0.13.0 // indirect
 	github.com/kaptinlin/go-i18n v0.2.12 // indirect
 	github.com/kaptinlin/jsonpointer v0.4.17 // indirect
-	github.com/kaptinlin/jsonschema v0.7.5 // indirect
+	github.com/kaptinlin/jsonschema v0.7.6 // indirect
 	github.com/kaptinlin/messageformat-go v0.4.18 // indirect
-	github.com/mailru/easyjson v0.9.1 // indirect
 	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
 	github.com/mitchellh/hashstructure/v2 v2.0.2 // indirect
 	github.com/muesli/mango v0.2.0 // indirect
@@ -95,8 +93,7 @@ require (
 	github.com/muesli/mango-pflag v0.2.0 // indirect
 	github.com/muesli/reflow v0.3.0 // indirect
 	github.com/muesli/roff v0.1.0 // indirect
-	github.com/openai/openai-go/v2 v2.7.1 // indirect
-	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/pelletier/go-toml/v2 v2.3.0 // indirect
 	github.com/sagikazarmark/locafero v0.12.0 // indirect
 	github.com/spf13/afero v1.15.0 // indirect
 	github.com/spf13/cast v1.10.0 // indirect
@@ -105,45 +102,44 @@ require (
 	github.com/tidwall/match v1.2.0 // indirect
 	github.com/tidwall/pretty v1.2.1 // indirect
 	github.com/tidwall/sjson v1.2.5 // indirect
-	github.com/wk8/go-ordered-map/v2 v2.1.8 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
-	github.com/yuin/goldmark v1.7.16 // indirect
+	github.com/yuin/goldmark v1.8.2 // indirect
 	github.com/yuin/goldmark-emoji v1.0.6 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
-	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.66.0 // indirect
-	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.66.0 // indirect
-	go.opentelemetry.io/otel v1.41.0 // indirect
-	go.opentelemetry.io/otel/metric v1.41.0 // indirect
-	go.opentelemetry.io/otel/trace v1.41.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.67.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0 // indirect
+	go.opentelemetry.io/otel v1.42.0 // indirect
+	go.opentelemetry.io/otel/metric v1.42.0 // indirect
+	go.opentelemetry.io/otel/trace v1.42.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
-	golang.org/x/crypto v0.48.0 // indirect
-	golang.org/x/exp v0.0.0-20260218203240-3dfff04db8fa // indirect
-	golang.org/x/net v0.51.0 // indirect
-	golang.org/x/oauth2 v0.35.0 // indirect
-	golang.org/x/time v0.14.0 // indirect
-	google.golang.org/api v0.269.0 // indirect
-	google.golang.org/genai v1.49.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20260226221140-a57be14db171 // indirect
-	google.golang.org/grpc v1.79.2 // indirect
+	golang.org/x/crypto v0.49.0 // indirect
+	golang.org/x/exp v0.0.0-20260312153236-7ab1446f8b90 // indirect
+	golang.org/x/net v0.52.0 // indirect
+	golang.org/x/oauth2 v0.36.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
+	google.golang.org/api v0.273.0 // indirect
+	google.golang.org/genai v1.51.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260319201613-d00831a3d3e7 // indirect
+	google.golang.org/grpc v1.79.3 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
 
 require (
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
-	github.com/charmbracelet/glamour v0.10.0
-	github.com/charmbracelet/x/ansi v0.11.6 // indirect
+	github.com/charmbracelet/glamour v1.0.0
+	github.com/charmbracelet/x/ansi v0.11.6
 	github.com/charmbracelet/x/term v0.2.2 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	github.com/mattn/go-runewidth v0.0.20 // indirect
+	github.com/mattn/go-runewidth v0.0.21 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.16.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
-	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/sync v0.20.0 // indirect
 	golang.org/x/sys v0.42.0 // indirect
-	golang.org/x/text v0.34.0 // indirect
+	golang.org/x/text v0.35.0
 )

go.sum

@@ -1,21 +1,17 @@
 charm.land/bubbles/v2 v2.0.0 h1:tE3eK/pHjmtrDiRdoC9uGNLgpopOd8fjhEe31B/ai5s=
 charm.land/bubbles/v2 v2.0.0/go.mod h1:rCHoleP2XhU8um45NTuOWBPNVHxnkXKTiZqcclL/qOI=
-charm.land/bubbletea/v2 v2.0.1 h1:B8e9zzK7x9JJ+XvHGF4xnYu9Xa0E0y0MyggY6dbaCfQ=
-charm.land/bubbletea/v2 v2.0.1/go.mod h1:3LRff2U4WIYXy7MTxfbAQ+AdfM3D8Xuvz2wbsOD9OHQ=
 charm.land/bubbletea/v2 v2.0.2 h1:4CRtRnuZOdFDTWSff9r8QFt/9+z6Emubz3aDMnf/dx0=
 charm.land/bubbletea/v2 v2.0.2/go.mod h1:3LRff2U4WIYXy7MTxfbAQ+AdfM3D8Xuvz2wbsOD9OHQ=
-charm.land/fantasy v0.11.1 h1:G1dRqkzEQ0RJN1Ls5mte8HOi0wFKxYd5bfnRAmeYvDk=
-charm.land/fantasy v0.11.1/go.mod h1:C8wNxWlw+b2z54zsTor9r1tG2GE2C4QotvAlgXh9KF8=
+charm.land/fantasy v0.17.1 h1:SQzfnyJPDuQWt6e//KKmQmEEXdqHMC0IZz10XwkLcEM=
+charm.land/fantasy v0.17.1/go.mod h1:FF5ALCCHETacHJPBqU42CtwMInYQ0ul52fdzIHQMbQk=
 charm.land/huh/v2 v2.0.3 h1:2cJsMqEPwSywGHvdlKsJyQKPtSJLVnFKyFbsYZTlLkU=
 charm.land/huh/v2 v2.0.3/go.mod h1:93eEveeeqn47MwiC3tf+2atZ2l7Is88rAtmZNZ8x9Wc=
-charm.land/lipgloss/v2 v2.0.0 h1:sd8N/B3x892oiOjFfBQdXBQp3cAkvjGaU5TvVZC3ivo=
-charm.land/lipgloss/v2 v2.0.0/go.mod h1:w6SnmsBFBmEFBodiEDurGS/sdUY/u1+v72DqUzc6J14=
-charm.land/lipgloss/v2 v2.0.1 h1:6Xzrn49+Py1Um5q/wZG1gWgER2+7dUyZ9XMEufqPSys=
-charm.land/lipgloss/v2 v2.0.1/go.mod h1:KjPle2Qd3YmvP1KL5OMHiHysGcNwq6u83MUjYkFvEkM=
+charm.land/lipgloss/v2 v2.0.2 h1:xFolbF8JdpNkM2cEPTfXEcW1p6NRzOWTSamRfYEw8cs=
+charm.land/lipgloss/v2 v2.0.2/go.mod h1:KjPle2Qd3YmvP1KL5OMHiHysGcNwq6u83MUjYkFvEkM=
 cloud.google.com/go v0.123.0 h1:2NAUJwPR47q+E35uaJeYoNhuNEM9kM8SjgRgdeOJUSE=
 cloud.google.com/go v0.123.0/go.mod h1:xBoMV08QcqUGuPW65Qfm1o9Y4zKZBpGS+7bImXLTAZU=
-cloud.google.com/go/auth v0.18.2 h1:+Nbt5Ev0xEqxlNjd6c+yYUeosQ5TtEUaNcN/3FozlaM=
-cloud.google.com/go/auth v0.18.2/go.mod h1:xD+oY7gcahcu7G2SG2DsBerfFxgPAJz17zz2joOFF3M=
+cloud.google.com/go/auth v0.19.0 h1:DGYwtbcsGsT1ywuxsIoWi1u/vlks0moIblQHgSDgQkQ=
+cloud.google.com/go/auth v0.19.0/go.mod h1:2Aph7BT2KnaSFOM0JDPyiYgNh6PL9vGMiP8CUIXZ+IY=
 cloud.google.com/go/auth/oauth2adapt v0.2.8 h1:keo8NaayQZ6wimpNSmW5OPc283g65QNIiLpZnkHRbnc=
 cloud.google.com/go/auth/oauth2adapt v0.2.8/go.mod h1:XQ9y31RkqZCcwJWNSx2Xvric3RrU88hAYYbjDWYDL+c=
 cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
@@ -38,82 +34,82 @@ github.com/alecthomas/repr v0.5.2 h1:SU73FTI9D1P5UNtvseffFSGmdNci/O6RsqzeXJtP0Qs
 github.com/alecthomas/repr v0.5.2/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=
 github.com/atotto/clipboard v0.1.4/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
-github.com/aws/aws-sdk-go-v2 v1.41.3 h1:4kQ/fa22KjDt13QCy1+bYADvdgcxpfH18f0zP542kZA=
-github.com/aws/aws-sdk-go-v2 v1.41.3/go.mod h1:mwsPRE8ceUUpiTgF7QmQIJ7lgsKUPQOUl3o72QBrE1o=
-github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.6 h1:N4lRUXZpZ1KVEUn6hxtco/1d2lgYhNn1fHkkl8WhlyQ=
-github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.6/go.mod h1:lyw7GFp3qENLh7kwzf7iMzAxDn+NzjXEAGjKS2UOKqI=
-github.com/aws/aws-sdk-go-v2/config v1.32.11 h1:ftxI5sgz8jZkckuUHXfC/wMUc8u3fG1vQS0plr2F2Zs=
-github.com/aws/aws-sdk-go-v2/config v1.32.11/go.mod h1:twF11+6ps9aNRKEDimksp923o44w/Thk9+8YIlzWMmo=
-github.com/aws/aws-sdk-go-v2/credentials v1.19.11 h1:NdV8cwCcAXrCWyxArt58BrvZJ9pZ9Fhf9w6Uh5W3Uyc=
-github.com/aws/aws-sdk-go-v2/credentials v1.19.11/go.mod h1:30yY2zqkMPdrvxBqzI9xQCM+WrlrZKSOpSJEsylVU+8=
-github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.19 h1:INUvJxmhdEbVulJYHI061k4TVuS3jzzthNvjqvVvTKM=
-github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.19/go.mod h1:FpZN2QISLdEBWkayloda+sZjVJL+e9Gl0k1SyTgcswU=
-github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.19 h1:/sECfyq2JTifMI2JPyZ4bdRN77zJmr6SrS1eL3augIA=
-github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.19/go.mod h1:dMf8A5oAqr9/oxOfLkC/c2LU/uMcALP0Rgn2BD5LWn0=
-github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.19 h1:AWeJMk33GTBf6J20XJe6qZoRSJo0WfUhsMdUKhoODXE=
-github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.19/go.mod h1:+GWrYoaAsV7/4pNHpwh1kiNLXkKaSoppxQq9lbH8Ejw=
-github.com/aws/aws-sdk-go-v2/internal/ini v1.8.5 h1:clHU5fm//kWS1C2HgtgWxfQbFbx4b6rx+5jzhgX9HrI=
-github.com/aws/aws-sdk-go-v2/internal/ini v1.8.5/go.mod h1:O3h0IK87yXci+kg6flUKzJnWeziQUKciKrLjcatSNcY=
-github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.6 h1:XAq62tBTJP/85lFD5oqOOe7YYgWxY9LvWq8plyDvDVg=
-github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.6/go.mod h1:x0nZssQ3qZSnIcePWLvcoFisRXJzcTVvYpAAdYX8+GI=
-github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.19 h1:X1Tow7suZk9UCJHE1Iw9GMZJJl0dAnKXXP1NaSDHwmw=
-github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.19/go.mod h1:/rARO8psX+4sfjUQXp5LLifjUt8DuATZ31WptNJTyQA=
-github.com/aws/aws-sdk-go-v2/service/signin v1.0.7 h1:Y2cAXlClHsXkkOvWZFXATr34b0hxxloeQu/pAZz2row=
-github.com/aws/aws-sdk-go-v2/service/signin v1.0.7/go.mod h1:idzZ7gmDeqeNrSPkdbtMp9qWMgcBwykA7P7Rzh5DXVU=
-github.com/aws/aws-sdk-go-v2/service/sso v1.30.12 h1:iSsvB9EtQ09YrsmIc44Heqlx5ByGErqhPK1ZQLppias=
-github.com/aws/aws-sdk-go-v2/service/sso v1.30.12/go.mod h1:fEWYKTRGoZNl8tZ77i61/ccwOMJdGxwOhWCkp6TXAr0=
-github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.16 h1:EnUdUqRP1CNzt2DkV67tJx6XDN4xlfBFm+bzeNOQVb0=
-github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.16/go.mod h1:Jic/xv0Rq/pFNCh3WwpH4BEqdbSAl+IyHro8LbibHD8=
-github.com/aws/aws-sdk-go-v2/service/sts v1.41.8 h1:XQTQTF75vnug2TXS8m7CVJfC2nniYPZnO1D4Np761Oo=
-github.com/aws/aws-sdk-go-v2/service/sts v1.41.8/go.mod h1:Xgx+PR1NUOjNmQY+tRMnouRp83JRM8pRMw/vCaVhPkI=
+github.com/aws/aws-sdk-go-v2 v1.41.4 h1:10f50G7WyU02T56ox1wWXq+zTX9I1zxG46HYuG1hH/k=
+github.com/aws/aws-sdk-go-v2 v1.41.4/go.mod h1:mwsPRE8ceUUpiTgF7QmQIJ7lgsKUPQOUl3o72QBrE1o=
+github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8 h1:eBMB84YGghSocM7PsjmmPffTa+1FBUeNvGvFou6V/4o=
+github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8/go.mod h1:lyw7GFp3qENLh7kwzf7iMzAxDn+NzjXEAGjKS2UOKqI=
+github.com/aws/aws-sdk-go-v2/config v1.32.12 h1:O3csC7HUGn2895eNrLytOJQdoL2xyJy0iYXhoZ1OmP0=
+github.com/aws/aws-sdk-go-v2/config v1.32.12/go.mod h1:96zTvoOFR4FURjI+/5wY1vc1ABceROO4lWgWJuxgy0g=
+github.com/aws/aws-sdk-go-v2/credentials v1.19.12 h1:oqtA6v+y5fZg//tcTWahyN9PEn5eDU/Wpvc2+kJ4aY8=
+github.com/aws/aws-sdk-go-v2/credentials v1.19.12/go.mod h1:U3R1RtSHx6NB0DvEQFGyf/0sbrpJrluENHdPy1j/3TE=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.20 h1:zOgq3uezl5nznfoK3ODuqbhVg1JzAGDUhXOsU0IDCAo=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.18.20/go.mod h1:z/MVwUARehy6GAg/yQ1GO2IMl0k++cu1ohP9zo887wE=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20 h1:CNXO7mvgThFGqOFgbNAP2nol2qAWBOGfqR/7tQlvLmc=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20/go.mod h1:oydPDJKcfMhgfcgBUZaG+toBbwy8yPWubJXBVERtI4o=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20 h1:tN6W/hg+pkM+tf9XDkWUbDEjGLb+raoBMFsTodcoYKw=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20/go.mod h1:YJ898MhD067hSHA6xYCx5ts/jEd8BSOLtQDL3iZsvbc=
+github.com/aws/aws-sdk-go-v2/internal/ini v1.8.6 h1:qYQ4pzQ2Oz6WpQ8T3HvGHnZydA72MnLuFK9tJwmrbHw=
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@@ -203,15 +203,13 @@ github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0
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@@ -230,10 +228,8 @@ github.com/muesli/roff v0.1.0 h1:YD0lalCotmYuF5HhZliKWlIx7IEhiXeSfq7hNjFqGF8=
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-google.golang.org/genai v1.49.0/go.mod h1:A3kkl0nyBjyFlNjgxIwKq70julKbIxpSxqKO5gw/gmk=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20260226221140-a57be14db171 h1:ggcbiqK8WWh6l1dnltU4BgWGIGo+EVYxCaAPih/zQXQ=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20260226221140-a57be14db171/go.mod h1:4Hqkh8ycfw05ld/3BWL7rJOSfebL2Q+DVDeRgYgxUU8=
-google.golang.org/grpc v1.79.2 h1:fRMD94s2tITpyJGtBBn7MkMseNpOZU8ZxgC3MMBaXRU=
-google.golang.org/grpc v1.79.2/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
+google.golang.org/api v0.273.0 h1:r/Bcv36Xa/te1ugaN1kdJ5LoA5Wj/cL+a4gj6FiPBjQ=
+google.golang.org/api v0.273.0/go.mod h1:JbAt7mF+XVmWu6xNP8/+CTiGH30ofmCmk9nM8d8fHew=
+google.golang.org/genai v1.51.0 h1:IZGuUqgfx40INv3hLFGCbOSGp0qFqm7LVmDghzNIYqg=
+google.golang.org/genai v1.51.0/go.mod h1:A3kkl0nyBjyFlNjgxIwKq70julKbIxpSxqKO5gw/gmk=
+google.golang.org/genproto v0.0.0-20260319201613-d00831a3d3e7 h1:XzmzkmB14QhVhgnawEVsOn6OFsnpyxNPRY9QV01dNB0=
+google.golang.org/genproto v0.0.0-20260319201613-d00831a3d3e7/go.mod h1:L43LFes82YgSonw6iTXTxXUX1OlULt4AQtkik4ULL/I=
+google.golang.org/genproto/googleapis/api v0.0.0-20260319201613-d00831a3d3e7 h1:41r6JMbpzBMen0R/4TZeeAmGXSJC7DftGINUodzTkPI=
+google.golang.org/genproto/googleapis/api v0.0.0-20260319201613-d00831a3d3e7/go.mod h1:EIQZ5bFCfRQDV4MhRle7+OgjNtZ6P1PiZBgAKuxXu/Y=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260319201613-d00831a3d3e7 h1:ndE4FoJqsIceKP2oYSnUZqhTdYufCYYkqwtFzfrhI7w=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260319201613-d00831a3d3e7/go.mod h1:4Hqkh8ycfw05ld/3BWL7rJOSfebL2Q+DVDeRgYgxUU8=
+google.golang.org/grpc v1.79.3 h1:sybAEdRIEtvcD68Gx7dmnwjZKlyfuc61Dyo9pGXXkKE=
+google.golang.org/grpc v1.79.3/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
 google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
 google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

internal/agent/agent.go

@@ -63,6 +63,18 @@ type ToolCallContentHandler func(content string)
 // ReasoningDeltaHandler is a function type for handling streaming reasoning/thinking deltas.
 type ReasoningDeltaHandler func(delta string)
 
+// ToolOutputHandler is a function type for handling streaming tool output chunks.
+// Used by tools like bash to stream output as it arrives rather than waiting
+// for the command to complete. The isStderr flag indicates if the chunk
+// contains stderr output.
+// Note: This is an alias for core.ToolOutputCallback to avoid import cycles.
+type ToolOutputHandler = core.ToolOutputCallback
+
+// StepUsageHandler is a function type for handling token usage after each
+// complete step in a multi-step agent turn. This enables real-time cost
+// tracking during long-running tool-calling conversations.
+type StepUsageHandler func(inputTokens, outputTokens, cacheReadTokens, cacheCreationTokens int64)
+
 // Agent represents an AI agent with core tool integration using the fantasy library.
 // Core tools (bash, read, write, edit, grep, find, ls) are registered as direct
 // fantasy.AgentTool implementations — no MCP layer, no serialization overhead.
@@ -171,7 +183,8 @@ func NewAgent(ctx context.Context, agentConfig *AgentConfig) (*Agent, error) {
 
 	// Pass generation parameters when available.
 	if agentConfig.ModelConfig != nil {
-		if agentConfig.ModelConfig.MaxTokens > 0 {
+		// Skip max_output_tokens for providers that don't support it (e.g., Codex OAuth)
+		if agentConfig.ModelConfig.MaxTokens > 0 && !providerResult.SkipMaxOutputTokens {
 			agentOpts = append(agentOpts, fantasy.WithMaxOutputTokens(int64(agentConfig.ModelConfig.MaxTokens)))
 		}
 		if agentConfig.ModelConfig.Temperature != nil {
@@ -218,7 +231,7 @@ func (a *Agent) GenerateWithLoop(ctx context.Context, messages []fantasy.Message
 	onResponse ResponseHandler, onToolCallContent ToolCallContentHandler,
 ) (*GenerateWithLoopResult, error) {
 	return a.GenerateWithLoopAndStreaming(ctx, messages, onToolCall, onToolExecution, onToolResult,
-		onResponse, onToolCallContent, nil, nil)
+		onResponse, onToolCallContent, nil, nil, nil, nil)
 }
 
 // GenerateWithLoopAndStreaming processes messages using the fantasy agent with streaming and callbacks.
@@ -229,8 +242,15 @@ func (a *Agent) GenerateWithLoopAndStreaming(ctx context.Context, messages []fan
 	onResponse ResponseHandler, onToolCallContent ToolCallContentHandler,
 	onStreamingResponse StreamingResponseHandler,
 	onReasoningDelta ReasoningDeltaHandler,
+	onToolOutput ToolOutputHandler,
+	onStepUsage StepUsageHandler,
 ) (*GenerateWithLoopResult, error) {
 
+	// Inject tool output handler into context for use by core tools (e.g., bash).
+	if onToolOutput != nil {
+		ctx = core.ContextWithToolOutputCallback(ctx, onToolOutput)
+	}
+
 	// Fantasy requires the current user input as Prompt, with prior messages as history.
 	// Extract the last user message text and files as the prompt, and pass everything
 	// before it as Messages. Files (e.g. clipboard images) are passed via the Files
@@ -249,8 +269,14 @@ func (a *Agent) GenerateWithLoopAndStreaming(ctx context.Context, messages []fan
 		onToolCallContent != nil || onStreamingResponse != nil || onReasoningDelta != nil
 
 	if a.streamingEnabled || hasCallbacks {
+		// Track completed step messages so we can return partial results
+		// on cancellation. Fantasy's Stream() discards accumulated steps
+		// when it returns an error, but the OnStepFinish callback fires
+		// for every step that completed before the error occurred.
+		var completedStepMessages []fantasy.Message
+
 		// Use fantasy's streaming agent
-		result, err := a.fantasyAgent.Stream(ctx, fantasy.AgentStreamCall{
+		streamCall := fantasy.AgentStreamCall{
 			Prompt:   prompt,
 			Files:    files,
 			Messages: history,
@@ -319,6 +345,10 @@ func (a *Agent) GenerateWithLoopAndStreaming(ctx context.Context, messages []fan
 
 			// Step callbacks for content that accompanies tool calls
 			OnStepFinish: func(step fantasy.StepResult) error {
+				// Accumulate messages from completed steps so they can be
+				// persisted even if a later step is cancelled.
+				completedStepMessages = append(completedStepMessages, step.Messages...)
+
 				if ctx.Err() != nil {
 					return ctx.Err()
 				}
@@ -328,10 +358,73 @@ func (a *Agent) GenerateWithLoopAndStreaming(ctx context.Context, messages []fan
 				if text != "" && len(toolCalls) > 0 && onToolCallContent != nil {
 					onToolCallContent(text)
 				}
+				// Emit step usage for real-time cost tracking
+				if onStepUsage != nil {
+					onStepUsage(step.Usage.InputTokens, step.Usage.OutputTokens,
+						step.Usage.CacheReadTokens, step.Usage.CacheCreationTokens)
+				}
 				return nil
 			},
-		})
+		}
+
+		// If a steer channel is attached to the context, wire up a
+		// PrepareStep function that drains the channel between steps
+		// and injects pending steer messages as user messages before
+		// the next LLM call. This enables graceful mid-turn steering
+		// without cancelling in-progress tool execution.
+		if steerCh := steerChFromContext(ctx); steerCh != nil {
+			onConsumed := steerConsumedFromContext(ctx)
+			streamCall.PrepareStep = func(
+				stepCtx context.Context,
+				opts fantasy.PrepareStepFunctionOptions,
+			) (context.Context, fantasy.PrepareStepResult, error) {
+				// Drain all pending steer messages (non-blocking).
+				var steered []string
+				for {
+					select {
+					case msg := <-steerCh:
+						steered = append(steered, msg)
+					default:
+						goto done
+					}
+				}
+			done:
+				result := fantasy.PrepareStepResult{
+					Model:    opts.Model,
+					Messages: opts.Messages,
+				}
+				if len(steered) > 0 {
+					// Inject each steer message as a user message so the
+					// LLM sees the redirection on the next step.
+					for _, text := range steered {
+						result.Messages = append(result.Messages,
+							fantasy.NewUserMessage(text))
+					}
+					// Notify that steer messages were consumed.
+					if onConsumed != nil {
+						onConsumed(len(steered))
+					}
+				}
+				return stepCtx, result, nil
+			}
+		}
+
+		result, err := a.fantasyAgent.Stream(ctx, streamCall)
 		if err != nil {
+			// On cancellation (or any error), return a partial result
+			// containing messages from completed steps so the caller can
+			// persist tool calls and results that finished before the
+			// cancellation. The original input messages are included so
+			// the caller sees the full conversation up to the point of
+			// cancellation.
+			if len(completedStepMessages) > 0 {
+				partialMessages := make([]fantasy.Message, 0, len(messages)+len(completedStepMessages))
+				partialMessages = append(partialMessages, messages...)
+				partialMessages = append(partialMessages, completedStepMessages...)
+				return &GenerateWithLoopResult{
+					ConversationMessages: partialMessages,
+				}, err
+			}
 			return nil, err
 		}
 
@@ -580,7 +673,8 @@ func (a *Agent) SetModel(ctx context.Context, config *models.ProviderConfig) err
 	}
 
 	// Pass generation parameters when available.
-	if config.MaxTokens > 0 {
+	// Skip max_output_tokens for providers that don't support it (e.g., Codex OAuth)
+	if config.MaxTokens > 0 && !providerResult.SkipMaxOutputTokens {
 		agentOpts = append(agentOpts, fantasy.WithMaxOutputTokens(int64(config.MaxTokens)))
 	}
 	if config.Temperature != nil {

internal/agent/steer.go

@@ -0,0 +1,35 @@
+package agent
+
+import "context"
+
+// steerChKey is the context key for the steer channel.
+type steerChKey struct{}
+
+// steerConsumedKey is the context key for the steer-consumed callback.
+type steerConsumedKey struct{}
+
+// ContextWithSteerCh returns a new context with the steer channel attached.
+// The agent's PrepareStep function checks this channel between steps and
+// injects any pending steer messages as user messages before the next LLM call.
+func ContextWithSteerCh(ctx context.Context, ch <-chan string) context.Context {
+	return context.WithValue(ctx, steerChKey{}, ch)
+}
+
+// ContextWithSteerConsumed returns a new context with a callback that fires
+// when steer messages are consumed by PrepareStep. The count argument is the
+// number of messages injected in this batch.
+func ContextWithSteerConsumed(ctx context.Context, fn func(count int)) context.Context {
+	return context.WithValue(ctx, steerConsumedKey{}, fn)
+}
+
+// steerChFromContext extracts the steer channel from the context, or nil.
+func steerChFromContext(ctx context.Context) <-chan string {
+	ch, _ := ctx.Value(steerChKey{}).(<-chan string)
+	return ch
+}
+
+// steerConsumedFromContext extracts the steer-consumed callback, or nil.
+func steerConsumedFromContext(ctx context.Context) func(int) {
+	fn, _ := ctx.Value(steerConsumedKey{}).(func(int))
+	return fn
+}

internal/app/app.go

@@ -3,6 +3,7 @@ package app
 import (
 	"context"
 	"fmt"
+	"os"
 	"sync"
 
 	tea "charm.land/bubbletea/v2"
@@ -159,11 +160,57 @@ func (a *App) QueueLength() int {
 	return len(a.queue)
 }
 
-// Steer cancels the current agent step (if running), clears the queue, and
-// sends a new message that will execute as soon as the current step finishes
-// cancelling. If the agent is idle, the message executes immediately.
-// This is the "steer" delivery mode for SendMessage.
-func (a *App) Steer(prompt string) {
+// Steer injects a steering message into the currently running agent turn.
+// If the agent is in a multi-step tool loop, the message is delivered after
+// the current tool execution finishes but before the next LLM call (graceful
+// mid-turn injection via Fantasy's PrepareStep). If the agent is streaming
+// a text-only response (no pending tool calls), the message waits until the
+// response completes and then executes as the next turn.
+//
+// If the agent is idle, the message starts executing immediately (same as Run).
+//
+// Returns the number of pending steer/queue items (0 = started immediately,
+// >0 = injected/queued). The caller must update UI state based on the return
+// value — Steer does NOT send events to the program to avoid deadlocking
+// when called from within Update().
+//
+// Satisfies ui.AppController.
+func (a *App) Steer(prompt string) int {
+	a.mu.Lock()
+
+	if a.closed {
+		a.mu.Unlock()
+		return 0
+	}
+
+	if !a.busy {
+		// Not busy — start immediately, same as Run().
+		item := queueItem{Prompt: prompt}
+		a.busy = true
+		a.wg.Add(1)
+		a.mu.Unlock()
+		go a.drainQueue(item)
+		return 0
+	}
+
+	a.mu.Unlock()
+
+	// Agent is busy — inject via the SDK's steer channel. The message
+	// will be picked up by PrepareStep between agent steps (after tool
+	// execution, before next LLM call). If PrepareStep doesn't fire
+	// (text-only response), drainQueue will pick it up after the turn.
+	if a.opts.Kit != nil {
+		a.opts.Kit.InjectSteer(prompt)
+	}
+	return 1
+}
+
+// InterruptAndSend cancels the current agent step (if running), clears the
+// queue, and sends a new message that will execute as soon as the current
+// step finishes cancelling. If the agent is idle, the message executes
+// immediately. This is the hard-cancel delivery mode used by extensions'
+// CancelAndSend.
+func (a *App) InterruptAndSend(prompt string) {
 	a.mu.Lock()
 
 	if a.closed {
@@ -217,6 +264,26 @@ func (a *App) GetTreeSession() *session.TreeManager {
 	return a.opts.TreeSession
 }
 
+// SwitchTreeSession replaces the active tree session with a new one and
+// reloads the in-memory message store from the new session's messages.
+// The old tree session is closed. Used by /resume to switch sessions.
+func (a *App) SwitchTreeSession(ts *session.TreeManager) {
+	// Close old session.
+	if old := a.opts.TreeSession; old != nil {
+		_ = old.Close()
+	}
+	a.opts.TreeSession = ts
+	// Also update the kit SDK's tree session so messages are persisted correctly.
+	if a.opts.Kit != nil {
+		a.opts.Kit.SetTreeSession(ts)
+	}
+	// Reload messages from new session.
+	a.store.Clear()
+	if ts != nil {
+		a.store.Replace(ts.GetFantasyMessages())
+	}
+}
+
 // AddContextMessage adds a user-role message to the conversation history
 // without triggering an LLM response. Used by the ! shell command prefix
 // to inject command output into context so the LLM can reference it in
@@ -385,6 +452,13 @@ func (a *App) Close() {
 
 	// Wait for background goroutines.
 	a.wg.Wait()
+
+	// Clean up empty session file on shutdown.
+	if ts := a.opts.TreeSession; ts != nil && ts.IsEmpty() {
+		if path := ts.GetFilePath(); path != "" {
+			_ = os.Remove(path)
+		}
+	}
 }
 
 // --------------------------------------------------------------------------
@@ -418,6 +492,24 @@ func (a *App) drainQueue(first queueItem) {
 		// Process all collected items as a single batch
 		a.runQueueBatch(items)
 
+		// Drain any unconsumed steer messages from the SDK channel.
+		// These arrive when the user steered during a text-only response
+		// (no tool calls, so PrepareStep didn't fire for a second step).
+		// They go to the front of the queue so they run next.
+		if a.opts.Kit != nil {
+			if leftover := a.opts.Kit.DrainSteer(); len(leftover) > 0 {
+				a.mu.Lock()
+				steerItems := make([]queueItem, len(leftover))
+				for i, text := range leftover {
+					steerItems[i] = queueItem{Prompt: text}
+				}
+				a.queue = append(steerItems, a.queue...)
+				a.mu.Unlock()
+				// Notify UI about the consumed steer messages.
+				a.sendEvent(SteerConsumedEvent{})
+			}
+		}
+
 		// Check if more items were queued while we were processing
 		a.mu.Lock()
 		hasMore := len(a.queue) > 0
@@ -470,47 +562,13 @@ func (a *App) runQueueBatch(items []queueItem) {
 	result, err := a.executeBatch(stepCtx, items, eventFn)
 	if err != nil {
 		if stepCtx.Err() != nil {
-			// Step was cancelled by the user (e.g. double-ESC). Send a
-			// cancellation event so the TUI can cut off the response
-			// cleanly without printing an error.
-			a.sendEvent(StepCancelledEvent{})
-			return
-		}
-		a.sendEvent(StepErrorEvent{Err: err})
-		return
-	}
-
-	a.sendEvent(StepCompleteEvent{ResponseText: result.Response})
-}
-
-// runQueueItem executes a single queue item: adds the user message to the store,
-// runs the agent step, and sends the appropriate event to the program.
-// Deprecated: Use runQueueBatch which handles both single and multiple items.
-func (a *App) runQueueItem(item queueItem) {
-	// Create a per-step cancellable context.
-	stepCtx, cancel := context.WithCancel(a.rootCtx)
-	a.mu.Lock()
-	a.cancelStep = cancel
-	a.mu.Unlock()
-	defer cancel()
-
-	// Build event function that sends to the registered tea.Program (if any).
-	a.mu.Lock()
-	prog := a.program
-	a.mu.Unlock()
-
-	eventFn := func(msg tea.Msg) {
-		if prog != nil {
-			prog.Send(msg)
-		}
-	}
-
-	result, err := a.executeStep(stepCtx, item.Prompt, eventFn, item.Files)
-	if err != nil {
-		if stepCtx.Err() != nil {
-			// Step was cancelled by the user (e.g. double-ESC). Send a
-			// cancellation event so the TUI can cut off the response
-			// cleanly without printing an error.
+			// Step was cancelled by the user (double-ESC). The SDK
+			// preserves the user message and any completed tool
+			// call/result pairs; only the in-progress message or tool
+			// call is discarded. Sync the in-memory store to match.
+			if ts := a.opts.TreeSession; ts != nil {
+				a.store.Replace(ts.GetFantasyMessages())
+			}
 			a.sendEvent(StepCancelledEvent{})
 			return
 		}
@@ -689,6 +747,15 @@ func (a *App) subscribeSDKEvents(sendFn func(tea.Msg)) func() {
 			sendFn(StreamChunkEvent{Content: ev.Chunk})
 		case kit.ReasoningDeltaEvent:
 			sendFn(ReasoningChunkEvent{Delta: ev.Delta})
+		case kit.ToolOutputEvent:
+			sendFn(ToolOutputEvent{
+				ToolCallID: ev.ToolCallID,
+				ToolName:   ev.ToolName,
+				Chunk:      ev.Chunk,
+				IsStderr:   ev.IsStderr,
+			})
+		case kit.SteerConsumedEvent:
+			sendFn(SteerConsumedEvent{})
 		}
 	}))
 
@@ -859,28 +926,39 @@ func (a *App) PrintBlockFromExtension(opts extensions.PrintBlockOpts) {
 }
 
 // updateUsageFromTurnResult records token usage from an SDK TurnResult into the
-// configured UsageTracker. This is the SDK-path equivalent of updateUsage.
+// configured UsageTracker. Called once per turn after the turn completes.
+//
+// Cost/token accumulation uses TotalUsage (sum across all tool-calling steps in
+// the turn). Context-window fill uses FinalUsage.InputTokens only — that is the
+// number of tokens sent to the model on the last API call, which equals the
+// actual context window occupation (all accumulated messages + tool results).
+// OutputTokens are not added here because they are the response length, not
+// context fill.
 func (a *App) updateUsageFromTurnResult(result *kit.TurnResult, userPrompt string) {
 	if a.opts.UsageTracker == nil || result == nil {
 		return
 	}
 
-	if result.TotalUsage != nil {
-		inputTokens := int(result.TotalUsage.InputTokens)
-		outputTokens := int(result.TotalUsage.OutputTokens)
-		if inputTokens > 0 && outputTokens > 0 {
-			cacheReadTokens := int(result.TotalUsage.CacheReadTokens)
-			cacheWriteTokens := int(result.TotalUsage.CacheCreationTokens)
-			a.opts.UsageTracker.UpdateUsage(inputTokens, outputTokens, cacheReadTokens, cacheWriteTokens)
-		} else {
-			a.opts.UsageTracker.EstimateAndUpdateUsage(userPrompt, result.Response)
-			return
-		}
+	// --- Accumulate cost/token totals for the session ---
+	if result.TotalUsage != nil && result.TotalUsage.InputTokens > 0 {
+		a.opts.UsageTracker.UpdateUsage(
+			int(result.TotalUsage.InputTokens),
+			int(result.TotalUsage.OutputTokens),
+			int(result.TotalUsage.CacheReadTokens),
+			int(result.TotalUsage.CacheCreationTokens),
+		)
+	} else {
+		// Provider didn't report token counts — fall back to character-based
+		// estimates so the footer shows something rather than nothing.
+		a.opts.UsageTracker.EstimateAndUpdateUsage(userPrompt, result.Response)
 	}
 
-	if result.FinalUsage != nil {
-		if ct := int(result.FinalUsage.InputTokens) + int(result.FinalUsage.OutputTokens); ct > 0 {
-			a.opts.UsageTracker.SetContextTokens(ct)
-		}
+	// --- Context window fill (drives the % bar) ---
+	// Use FinalUsage.InputTokens: the input token count of the last API call
+	// equals the number of tokens currently occupying the context window.
+	// Adding OutputTokens would overstate fill since the response is not part
+	// of the context that was *sent* to the model.
+	if result.FinalUsage != nil && result.FinalUsage.InputTokens > 0 {
+		a.opts.UsageTracker.SetContextTokens(int(result.FinalUsage.InputTokens))
 	}
 }

internal/app/events.go

@@ -54,6 +54,19 @@ type ToolResultEvent struct {
 	IsError bool
 }
 
+// ToolOutputEvent is sent when a tool produces streaming output chunks (e.g., bash output).
+// This allows the TUI to display tool output as it arrives, before the tool completes.
+type ToolOutputEvent struct {
+	// ToolCallID is the stable identifier for the tool call producing output.
+	ToolCallID string
+	// ToolName is the name of the tool producing output.
+	ToolName string
+	// Chunk is a piece of the tool's output text.
+	Chunk string
+	// IsStderr indicates whether this chunk came from stderr.
+	IsStderr bool
+}
+
 // ToolCallContentEvent is sent when a step includes text content alongside tool calls.
 // This allows the TUI to display assistant commentary that accompanies tool usage.
 type ToolCallContentEvent struct {
@@ -128,6 +141,12 @@ type CompactErrorEvent struct {
 	Err error
 }
 
+// SteerConsumedEvent is sent when one or more steering messages have been
+// consumed — either injected mid-turn via PrepareStep, or drained into the
+// queue after a turn completes. The TUI uses this to clear the steering
+// badge from the display.
+type SteerConsumedEvent struct{}
+
 // ModelChangedEvent is sent when an extension changes the active model via
 // ctx.SetModel. The TUI updates the model name shown in the status bar and
 // message attribution.

internal/auth/credentials.go

@@ -10,9 +10,10 @@ import (
 )
 
 // CredentialStore holds all stored credentials for various providers.
-// Currently supports Anthropic credentials with both OAuth and API key authentication methods.
+// Currently supports Anthropic and OpenAI credentials with both OAuth and API key authentication methods.
 type CredentialStore struct {
 	Anthropic *AnthropicCredentials `json:"anthropic,omitempty"`
+	OpenAI    *OpenAICredentials    `json:"openai,omitempty"`
 }
 
 // AnthropicCredentials holds Anthropic API credentials supporting both OAuth
@@ -28,6 +29,20 @@ type AnthropicCredentials struct {
 	CreatedAt    time.Time `json:"created_at"`
 }
 
+// OpenAICredentials holds OpenAI API credentials supporting both OAuth
+// and API key authentication methods. The Type field indicates which authentication
+// method is being used. For OAuth, tokens are stored with expiration timestamps
+// for automatic refresh. For API keys, only the key itself is stored.
+type OpenAICredentials struct {
+	Type         string    `json:"type"`                    // "oauth" or "api_key"
+	APIKey       string    `json:"api_key,omitempty"`       // For API key auth
+	AccessToken  string    `json:"access_token,omitempty"`  // For OAuth
+	RefreshToken string    `json:"refresh_token,omitempty"` // For OAuth
+	ExpiresAt    int64     `json:"expires_at,omitempty"`    // For OAuth
+	AccountID    string    `json:"account_id,omitempty"`    // For OAuth (ChatGPT account ID)
+	CreatedAt    time.Time `json:"created_at"`
+}
+
 // IsExpired checks if the OAuth token is expired based on the ExpiresAt timestamp.
 // Returns false for API key authentication or if no expiration is set.
 func (c *AnthropicCredentials) IsExpired() bool {
@@ -48,6 +63,26 @@ func (c *AnthropicCredentials) NeedsRefresh() bool {
 	return time.Now().Unix() >= (c.ExpiresAt - 300) // 5 minutes buffer
 }
 
+// IsExpired checks if the OAuth token is expired based on the ExpiresAt timestamp.
+// Returns false for API key authentication or if no expiration is set.
+func (c *OpenAICredentials) IsExpired() bool {
+	if c.Type != "oauth" || c.ExpiresAt == 0 {
+		return false
+	}
+	return time.Now().Unix() >= c.ExpiresAt
+}
+
+// NeedsRefresh checks if the OAuth token needs refresh, returning true if the token
+// will expire within the next 5 minutes. This allows for proactive token refresh
+// to avoid authentication failures during operations. Returns false for API key
+// authentication or if no expiration is set.
+func (c *OpenAICredentials) NeedsRefresh() bool {
+	if c.Type != "oauth" || c.ExpiresAt == 0 {
+		return false
+	}
+	return time.Now().Unix() >= (c.ExpiresAt - 300) // 5 minutes buffer
+}
+
 // CredentialManager handles secure storage and retrieval of authentication credentials.
 // It manages a JSON file stored in the user's config directory with appropriate
 // file permissions for security.
@@ -212,6 +247,142 @@ func (cm *CredentialManager) HasAnthropicCredentials() (bool, error) {
 	}
 }
 
+// SetOpenAICredentials stores OpenAI API key credentials. It validates the
+// API key format before storing. The API key must start with "sk-" and be
+// at least 20 characters long. Returns an error if the API key is invalid or
+// if storage fails.
+func (cm *CredentialManager) SetOpenAICredentials(apiKey string) error {
+	if err := validateOpenAIAPIKey(apiKey); err != nil {
+		return err
+	}
+
+	store, err := cm.LoadCredentials()
+	if err != nil {
+		return err
+	}
+
+	store.OpenAI = &OpenAICredentials{
+		Type:      "api_key",
+		APIKey:    apiKey,
+		CreatedAt: time.Now(),
+	}
+
+	return cm.SaveCredentials(store)
+}
+
+// GetOpenAICredentials retrieves stored OpenAI credentials. Returns nil if
+// no credentials are stored. The returned credentials may be either OAuth or API
+// key type, check the Type field to determine which.
+func (cm *CredentialManager) GetOpenAICredentials() (*OpenAICredentials, error) {
+	store, err := cm.LoadCredentials()
+	if err != nil {
+		return nil, err
+	}
+
+	return store.OpenAI, nil
+}
+
+// RemoveOpenAICredentials removes stored OpenAI credentials from storage.
+// If this was the only credential stored, the entire credentials file is removed.
+// Returns an error if the removal fails.
+func (cm *CredentialManager) RemoveOpenAICredentials() error {
+	store, err := cm.LoadCredentials()
+	if err != nil {
+		return err
+	}
+
+	store.OpenAI = nil
+
+	// If store is empty, remove the file entirely
+	if store.Anthropic == nil && store.OpenAI == nil {
+		if err := os.Remove(cm.credentialsPath); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("failed to remove credentials file: %w", err)
+		}
+		return nil
+	}
+
+	return cm.SaveCredentials(store)
+}
+
+// HasOpenAICredentials checks if valid OpenAI credentials are stored.
+// Returns true if either a non-empty OAuth access token or API key is present,
+// false otherwise. Returns an error if credentials cannot be loaded.
+func (cm *CredentialManager) HasOpenAICredentials() (bool, error) {
+	creds, err := cm.GetOpenAICredentials()
+	if err != nil {
+		return false, err
+	}
+	if creds == nil {
+		return false, nil
+	}
+
+	// Check based on credential type
+	switch creds.Type {
+	case "oauth":
+		return creds.AccessToken != "", nil
+	case "api_key":
+		return creds.APIKey != "", nil
+	default:
+		return false, nil
+	}
+}
+
+// SetOpenAIOAuthCredentials stores OpenAI OAuth credentials in the credential manager's secure storage.
+// The credentials should include access token, refresh token, and expiration information.
+// Returns an error if the credentials cannot be saved.
+func (cm *CredentialManager) SetOpenAIOAuthCredentials(creds *OpenAICredentials) error {
+	store, err := cm.LoadCredentials()
+	if err != nil {
+		return err
+	}
+
+	store.OpenAI = creds
+	return cm.SaveCredentials(store)
+}
+
+// GetValidOpenAIAccessToken returns a valid access token for API requests. For OAuth credentials,
+// it automatically refreshes the token if it's expired or about to expire. For API key
+// credentials, it simply returns the API key. Returns an error if no credentials are found,
+// if token refresh fails, or if the credential type is unknown.
+func (cm *CredentialManager) GetValidOpenAIAccessToken() (string, error) {
+	creds, err := cm.GetOpenAICredentials()
+	if err != nil {
+		return "", err
+	}
+
+	if creds == nil {
+		return "", fmt.Errorf("no credentials found")
+	}
+
+	// For API key auth, return the API key
+	if creds.Type == "api_key" {
+		return creds.APIKey, nil
+	}
+
+	// For OAuth, check if token needs refresh
+	if creds.Type == "oauth" {
+		if creds.NeedsRefresh() {
+			// Refresh the token
+			client := NewOpenAIOAuthClient()
+			newCreds, err := client.RefreshToken(creds.RefreshToken)
+			if err != nil {
+				return "", fmt.Errorf("failed to refresh token: %w", err)
+			}
+
+			// Update stored credentials
+			if err := cm.SetOpenAIOAuthCredentials(newCreds); err != nil {
+				return "", fmt.Errorf("failed to save refreshed token: %w", err)
+			}
+
+			return newCreds.AccessToken, nil
+		}
+
+		return creds.AccessToken, nil
+	}
+
+	return "", fmt.Errorf("unknown credential type: %s", creds.Type)
+}
+
 // GetCredentialsPath returns the absolute path to the credentials JSON file.
 // This is useful for debugging or displaying the storage location to users.
 func (cm *CredentialManager) GetCredentialsPath() string {
@@ -238,6 +409,26 @@ func validateAnthropicAPIKey(apiKey string) error {
 	return nil
 }
 
+// validateOpenAIAPIKey validates the format of an OpenAI API key
+func validateOpenAIAPIKey(apiKey string) error {
+	apiKey = strings.TrimSpace(apiKey)
+
+	if apiKey == "" {
+		return fmt.Errorf("API key cannot be empty")
+	}
+
+	// OpenAI API keys typically start with "sk-" and are quite long
+	if !strings.HasPrefix(apiKey, "sk-") {
+		return fmt.Errorf("invalid OpenAI API key format (should start with 'sk-')")
+	}
+
+	if len(apiKey) < 20 {
+		return fmt.Errorf("API key appears to be too short")
+	}
+
+	return nil
+}
+
 // GetAnthropicAPIKey retrieves an Anthropic API key from multiple sources in priority order:
 // 1. Command-line flag value (highest priority)
 // 2. Stored credentials (OAuth or API key)

internal/auth/oauth.go

@@ -7,6 +7,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 	"strings"
@@ -30,6 +31,7 @@ type OAuthClient struct {
 type AuthData struct {
 	URL      string
 	Verifier string
+	State    string // Optional state parameter for CSRF protection
 }
 
 // NewOAuthClient creates a new OAuth client configured for Anthropic's OAuth service.
@@ -199,6 +201,270 @@ func (c *OAuthClient) parseCodeAndState(code string) (parsedCode, parsedState st
 	return
 }
 
+// OpenAIOAuthClient handles OAuth 2.0 authentication flow with OpenAI Codex (ChatGPT Plus/Pro).
+// This uses OpenAI's auth0-based OAuth service for ChatGPT account authentication.
+type OpenAIOAuthClient struct {
+	ClientID     string
+	AuthorizeURL string
+	TokenURL     string
+	RedirectURI  string
+	Scopes       string
+}
+
+// NewOpenAIOAuthClient creates a new OAuth client configured for OpenAI Codex OAuth.
+// This uses the public client ID for CLI applications with PKCE for security.
+func NewOpenAIOAuthClient() *OpenAIOAuthClient {
+	return &OpenAIOAuthClient{
+		// Public client ID for OpenAI Codex CLI OAuth
+		ClientID:     "app_EMoamEEZ73f0CkXaXp7hrann",
+		AuthorizeURL: "https://auth.openai.com/oauth/authorize",
+		TokenURL:     "https://auth.openai.com/oauth/token",
+		RedirectURI:  "http://localhost:1455/auth/callback",
+		Scopes:       "openid profile email offline_access",
+	}
+}
+
+// GetAuthorizationURL generates a complete authorization URL for the OAuth flow with
+// PKCE parameters. Returns an AuthData structure containing the URL for user
+// authentication and the PKCE verifier for the subsequent code exchange.
+func (c *OpenAIOAuthClient) GetAuthorizationURL() (*AuthData, error) {
+	verifier, challenge, err := generatePKCE()
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate PKCE: %w", err)
+	}
+
+	// Generate random state
+	stateBytes := make([]byte, 16)
+	if _, err := rand.Read(stateBytes); err != nil {
+		return nil, fmt.Errorf("failed to generate state: %w", err)
+	}
+	state := fmt.Sprintf("%x", stateBytes)
+
+	params := url.Values{
+		"response_type":              {"code"},
+		"client_id":                  {c.ClientID},
+		"redirect_uri":               {c.RedirectURI},
+		"scope":                      {c.Scopes},
+		"code_challenge":             {challenge},
+		"code_challenge_method":      {"S256"},
+		"state":                      {state},
+		"id_token_add_organizations": {"true"},
+		"codex_cli_simplified_flow":  {"true"},
+		"originator":                 {"kit"},
+	}
+
+	authURL := fmt.Sprintf("%s?%s", c.AuthorizeURL, params.Encode())
+
+	return &AuthData{
+		URL:      authURL,
+		Verifier: verifier,
+		State:    state,
+	}, nil
+}
+
+// ExchangeCode exchanges an authorization code for access and refresh tokens.
+// The code parameter should be the authorization code received from the OAuth callback.
+// The verifier parameter must be the same PKCE verifier generated during GetAuthorizationURL.
+// Returns OpenAICredentials containing the tokens, expiration, and account ID.
+func (c *OpenAIOAuthClient) ExchangeCode(code, verifier string) (*OpenAICredentials, error) {
+	return c.exchangeAuthorizationCode(code, verifier, c.RedirectURI)
+}
+
+// exchangeAuthorizationCode performs the token exchange with the OAuth server
+func (c *OpenAIOAuthClient) exchangeAuthorizationCode(code, verifier, redirectUri string) (*OpenAICredentials, error) {
+	data := url.Values{
+		"grant_type":    {"authorization_code"},
+		"client_id":     {c.ClientID},
+		"code":          {code},
+		"code_verifier": {verifier},
+		"redirect_uri":  {redirectUri},
+	}
+
+	req, err := http.NewRequestWithContext(context.Background(), "POST", c.TokenURL, strings.NewReader(data.Encode()))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to make token request: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("token exchange failed: %s", string(body))
+	}
+
+	var tokenResp struct {
+		AccessToken  string `json:"access_token"`
+		RefreshToken string `json:"refresh_token"`
+		ExpiresIn    int    `json:"expires_in"`
+		IDToken      string `json:"id_token"`
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
+		return nil, fmt.Errorf("failed to decode token response: %w", err)
+	}
+
+	if tokenResp.AccessToken == "" || tokenResp.RefreshToken == "" {
+		return nil, fmt.Errorf("token response missing required fields")
+	}
+
+	// Extract account ID from JWT token
+	accountID := extractOpenAIAccountID(tokenResp.AccessToken)
+	if accountID == "" {
+		return nil, fmt.Errorf("failed to extract account ID from token")
+	}
+
+	return &OpenAICredentials{
+		Type:         "oauth",
+		AccessToken:  tokenResp.AccessToken,
+		RefreshToken: tokenResp.RefreshToken,
+		ExpiresAt:    time.Now().Unix() + int64(tokenResp.ExpiresIn),
+		CreatedAt:    time.Now(),
+		AccountID:    accountID,
+	}, nil
+}
+
+// RefreshToken refreshes an expired or expiring access token using a refresh token.
+// Returns new OpenAICredentials with updated access token, refresh token (may be
+// rotated), and new expiration timestamp. Returns an error if the refresh fails or
+// the refresh token is invalid.
+func (c *OpenAIOAuthClient) RefreshToken(refreshToken string) (*OpenAICredentials, error) {
+	data := url.Values{
+		"grant_type":    {"refresh_token"},
+		"refresh_token": {refreshToken},
+		"client_id":     {c.ClientID},
+	}
+
+	req, err := http.NewRequestWithContext(context.Background(), "POST", c.TokenURL, strings.NewReader(data.Encode()))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to make refresh request: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("token refresh failed: %s", string(body))
+	}
+
+	var tokenResp struct {
+		AccessToken  string `json:"access_token"`
+		RefreshToken string `json:"refresh_token"`
+		ExpiresIn    int    `json:"expires_in"`
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
+		return nil, fmt.Errorf("failed to decode refresh response: %w", err)
+	}
+
+	if tokenResp.AccessToken == "" || tokenResp.RefreshToken == "" {
+		return nil, fmt.Errorf("refresh response missing required fields")
+	}
+
+	// Extract account ID from JWT token
+	accountID := extractOpenAIAccountID(tokenResp.AccessToken)
+	if accountID == "" {
+		return nil, fmt.Errorf("failed to extract account ID from refreshed token")
+	}
+
+	return &OpenAICredentials{
+		Type:         "oauth",
+		AccessToken:  tokenResp.AccessToken,
+		RefreshToken: tokenResp.RefreshToken,
+		ExpiresAt:    time.Now().Unix() + int64(tokenResp.ExpiresIn),
+		CreatedAt:    time.Now(),
+		AccountID:    accountID,
+	}, nil
+}
+
+// extractOpenAIAccountID extracts the ChatGPT account ID from a JWT access token.
+// The account ID is stored in the claim path https://api.openai.com/auth.chatgpt_account_id
+func extractOpenAIAccountID(token string) string {
+	// JWT tokens are base64-encoded JSON payloads
+	parts := strings.Split(token, ".")
+	if len(parts) != 3 {
+		return ""
+	}
+
+	// Decode payload (second part)
+	payload := parts[1]
+	// Add padding if needed
+	if len(payload)%4 != 0 {
+		payload += strings.Repeat("=", 4-len(payload)%4)
+	}
+
+	decoded, err := base64.URLEncoding.DecodeString(payload)
+	if err != nil {
+		return ""
+	}
+
+	var claims map[string]any
+	if err := json.Unmarshal(decoded, &claims); err != nil {
+		return ""
+	}
+
+	// Navigate to the claim path: https://api.openai.com/auth.chatgpt_account_id
+	authPath, ok := claims["https://api.openai.com/auth"].(map[string]any)
+	if !ok {
+		return ""
+	}
+
+	accountID, ok := authPath["chatgpt_account_id"].(string)
+	if !ok {
+		return ""
+	}
+
+	return accountID
+}
+
+// ParseOpenAIAuthorizationInput parses various forms of authorization input:
+// - Full callback URL: http://localhost:1455/auth/callback?code=xxx&state=yyy
+// - Code#State format: abc123#state456
+// - Query string: code=abc123&state=state456
+// - Just the code: abc123
+func ParseOpenAIAuthorizationInput(input string) (code, state string) {
+	input = strings.TrimSpace(input)
+	if input == "" {
+		return "", ""
+	}
+
+	// Try parsing as URL
+	if strings.HasPrefix(input, "http") {
+		if u, err := url.Parse(input); err == nil {
+			return u.Query().Get("code"), u.Query().Get("state")
+		}
+	}
+
+	// Try code#state format
+	if strings.Contains(input, "#") {
+		parts := strings.SplitN(input, "#", 2)
+		return parts[0], parts[1]
+	}
+
+	// Try query string format
+	if strings.Contains(input, "code=") {
+		if values, err := url.ParseQuery(input); err == nil {
+			return values.Get("code"), values.Get("state")
+		}
+	}
+
+	// Assume it's just the code
+	return input, ""
+}
+
 // SetOAuthCredentials stores OAuth credentials in the credential manager's secure storage.
 // The credentials should include access token, refresh token, and expiration information.
 // Returns an error if the credentials cannot be saved.

internal/compaction/compaction.go

@@ -5,10 +5,18 @@
 // messages (KeepRecentTokens, default 20 000) rather than a fixed message
 // count. Auto-compaction fires when estimated context usage exceeds
 // contextWindow − ReserveTokens.
+//
+// Features modelled after pi's compaction system:
+//   - Tool result truncation (2000 char max) during serialisation
+//   - Split turn handling: when a single turn exceeds the keep budget,
+//     the turn prefix is summarised separately and merged
+//   - Cumulative file tracking: read and modified files extracted from
+//     tool calls and carried forward across compactions
 package compaction
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -66,10 +74,13 @@ func ShouldCompact(messages []fantasy.Message, contextWindow int, reserveTokens
 
 // CompactionResult contains statistics from a compaction operation.
 type CompactionResult struct {
-	Summary         string // LLM-generated summary of compacted messages
-	OriginalTokens  int    // Estimated token count before compaction
-	CompactedTokens int    // Estimated token count after compaction
-	MessagesRemoved int    // Number of messages replaced by the summary
+	Summary         string   // LLM-generated summary of compacted messages
+	OriginalTokens  int      // Estimated token count before compaction
+	CompactedTokens int      // Estimated token count after compaction
+	MessagesRemoved int      // Number of messages replaced by the summary
+	CutPoint        int      // Index in the original messages where the cut was made
+	ReadFiles       []string // Files read during the compacted conversation
+	ModifiedFiles   []string // Files modified during the compacted conversation
 }
 
 // CompactionOptions configures compaction behaviour. Token-based defaults
@@ -130,8 +141,34 @@ Use this EXACT format:
 - [Any data, examples, or references needed to continue]
 - [Or "(none)" if not applicable]
 
+<read-files>
+[One file path per line for files that were read during the conversation]
+</read-files>
+
+<modified-files>
+[One file path per line for files that were created, edited, or written during the conversation]
+</modified-files>
+
 Keep each section concise. Preserve exact file paths, function names, and error messages.`
 
+// ---------------------------------------------------------------------------
+// Tool result truncation
+// ---------------------------------------------------------------------------
+
+// maxToolResultChars is the maximum length of tool result text preserved
+// during serialisation. Longer results are truncated with a marker.
+const maxToolResultChars = 2000
+
+// truncateToolResult truncates text to maxToolResultChars, appending a
+// marker indicating how many characters were removed.
+func truncateToolResult(text string) string {
+	if len(text) <= maxToolResultChars {
+		return text
+	}
+	truncated := len(text) - maxToolResultChars
+	return text[:maxToolResultChars] + fmt.Sprintf("\n[...%d chars truncated]", truncated)
+}
+
 // ---------------------------------------------------------------------------
 // Cut point (token-based)
 // ---------------------------------------------------------------------------
@@ -143,11 +180,26 @@ func isValidCutPoint(msg fantasy.Message) bool {
 	return msg.Role != fantasy.MessageRoleTool
 }
 
+// findTurnStart returns the index of the user message that starts the turn
+// containing messages[idx]. A "turn" starts with a user message and includes
+// all subsequent assistant/tool messages until the next user message.
+func findTurnStart(messages []fantasy.Message, idx int) int {
+	for i := idx; i >= 0; i-- {
+		if messages[i].Role == fantasy.MessageRoleUser {
+			return i
+		}
+	}
+	return 0
+}
+
 // FindCutPoint walks backward from the end of messages, accumulating tokens
 // until the keepRecentTokens budget is filled. Returns the index that
 // separates "old" messages (0..cutPoint-1, to be summarised) from "recent"
 // messages (cutPoint..end, to be preserved).
 //
+// The cut point prefers turn boundaries (user messages). When a single turn
+// exceeds the budget, the cut lands mid-turn (IsSplitTurn returns true).
+//
 // Returns 0 if there are fewer than 2 messages or all messages fit within
 // the keep budget.
 func FindCutPoint(messages []fantasy.Message, keepRecentTokens int) int {
@@ -193,6 +245,23 @@ func FindCutPoint(messages []fantasy.Message, keepRecentTokens int) int {
 	return 0
 }
 
+// IsSplitTurn returns true if the cut point lands in the middle of a turn
+// (i.e. the message at cutPoint is not a user message, meaning we're
+// splitting a single turn's assistant/tool messages).
+func IsSplitTurn(messages []fantasy.Message, cutPoint int) bool {
+	if cutPoint <= 0 || cutPoint >= len(messages) {
+		return false
+	}
+	// If the cut point is at a user message, it's a clean turn boundary.
+	if messages[cutPoint].Role == fantasy.MessageRoleUser {
+		return false
+	}
+	// Otherwise we're cutting mid-turn — check if the turn started before
+	// the cut point.
+	turnStart := findTurnStart(messages, cutPoint)
+	return turnStart < cutPoint
+}
+
 // forceCutPoint returns a cut point that keeps only the last non-tool
 // message, summarising everything before it. Used when the budget-based
 // FindCutPoint returns 0 but the caller wants to compact anyway (manual
@@ -207,12 +276,104 @@ func forceCutPoint(messages []fantasy.Message) int {
 	return 0
 }
 
+// ---------------------------------------------------------------------------
+// File tracking
+// ---------------------------------------------------------------------------
+
+// fileOps contains cumulative file operation tracking.
+type fileOps struct {
+	ReadFiles     map[string]bool
+	ModifiedFiles map[string]bool
+}
+
+func newFileOps() *fileOps {
+	return &fileOps{
+		ReadFiles:     make(map[string]bool),
+		ModifiedFiles: make(map[string]bool),
+	}
+}
+
+// extractFileOps scans messages for tool calls and extracts file paths.
+// It recognises the built-in Kit tools: read, write, edit, bash, grep, find, ls.
+func extractFileOps(messages []fantasy.Message) *fileOps {
+	ops := newFileOps()
+	for _, msg := range messages {
+		for _, part := range msg.Content {
+			tc, ok := part.(fantasy.ToolCallPart)
+			if !ok {
+				continue
+			}
+
+			// Parse the JSON input to extract path arguments.
+			var args map[string]any
+			if err := json.Unmarshal([]byte(tc.Input), &args); err != nil {
+				continue
+			}
+
+			path, _ := args["path"].(string)
+			if path == "" {
+				continue
+			}
+
+			switch tc.ToolName {
+			case "read", "grep", "find", "ls":
+				ops.ReadFiles[path] = true
+			case "write", "edit":
+				ops.ModifiedFiles[path] = true
+			}
+		}
+	}
+	return ops
+}
+
+// merge combines another fileOps into this one (for cumulative tracking).
+func (f *fileOps) merge(other *fileOps) {
+	if other == nil {
+		return
+	}
+	for k := range other.ReadFiles {
+		f.ReadFiles[k] = true
+	}
+	for k := range other.ModifiedFiles {
+		f.ModifiedFiles[k] = true
+	}
+}
+
+// mergeSlices adds previously tracked file lists (from a prior compaction).
+func (f *fileOps) mergeSlices(readFiles, modifiedFiles []string) {
+	for _, p := range readFiles {
+		f.ReadFiles[p] = true
+	}
+	for _, p := range modifiedFiles {
+		f.ModifiedFiles[p] = true
+	}
+}
+
+// sortedKeys returns the keys of a bool map sorted alphabetically.
+func sortedKeys(m map[string]bool) []string {
+	if len(m) == 0 {
+		return nil
+	}
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	// Simple sort — no need for sort package for small lists.
+	for i := 0; i < len(keys); i++ {
+		for j := i + 1; j < len(keys); j++ {
+			if keys[j] < keys[i] {
+				keys[i], keys[j] = keys[j], keys[i]
+			}
+		}
+	}
+	return keys
+}
+
 // ---------------------------------------------------------------------------
 // Message serialisation
 // ---------------------------------------------------------------------------
 
-// roleLabel returns a human-readable label for a fantasy message role,
-
+// roleLabel returns a human-readable label for a fantasy message role.
 func roleLabel(role fantasy.MessageRole) string {
 	switch role {
 	case fantasy.MessageRoleUser:
@@ -229,16 +390,26 @@ func roleLabel(role fantasy.MessageRole) string {
 }
 
 // serializeMessages converts a slice of fantasy messages into a plain-text
-// representation suitable for sending to the summarisation LLM. The format
-
+// representation suitable for sending to the summarisation LLM. Tool result
+// text is truncated to maxToolResultChars to keep the summarisation request
+// within reasonable token budgets.
 func serializeMessages(messages []fantasy.Message) string {
 	var sb strings.Builder
 	for _, msg := range messages {
 		sb.WriteString(roleLabel(msg.Role))
 		sb.WriteString(":\n")
 		for _, part := range msg.Content {
-			if tp, ok := part.(fantasy.TextPart); ok {
-				sb.WriteString(tp.Text)
+			switch p := part.(type) {
+			case fantasy.TextPart:
+				if msg.Role == fantasy.MessageRoleTool {
+					sb.WriteString(truncateToolResult(p.Text))
+				} else {
+					sb.WriteString(p.Text)
+				}
+			case fantasy.ToolCallPart:
+				fmt.Fprintf(&sb, "[Tool call: %s(%s)]", p.ToolName, truncateToolResult(p.Input))
+			case fantasy.ReasoningPart:
+				fmt.Fprintf(&sb, "[Thinking]: %s", truncateToolResult(p.Text))
 			}
 		}
 		sb.WriteString("\n\n")
@@ -250,6 +421,13 @@ func serializeMessages(messages []fantasy.Message) string {
 // Compact
 // ---------------------------------------------------------------------------
 
+// PreviousCompaction carries file tracking state from a prior compaction so
+// that file operations accumulate across multiple compactions.
+type PreviousCompaction struct {
+	ReadFiles     []string
+	ModifiedFiles []string
+}
+
 // Compact summarises older messages using the LLM, returning the compaction
 // result and a new message slice (summary message + preserved recent
 // messages).
@@ -261,12 +439,16 @@ func serializeMessages(messages []fantasy.Message) string {
 // customInstructions is optional text appended to the summary prompt (e.g.
 // "Focus on the API design decisions"). Pass "" to use the default prompt
 // only.
+//
+// prev carries file tracking from a previous compaction for cumulative
+// tracking. Pass nil if there is no prior compaction.
 func Compact(
 	ctx context.Context,
 	model fantasy.LanguageModel,
 	messages []fantasy.Message,
 	opts CompactionOptions,
 	customInstructions string,
+	prev *PreviousCompaction,
 ) (*CompactionResult, []fantasy.Message, error) {
 	opts.defaults()
 
@@ -289,30 +471,30 @@ func Compact(
 	recentMessages := messages[cutPoint:]
 	originalTokens := EstimateMessageTokens(messages)
 
-	// Serialise old messages to text.
-	conversationText := serializeMessages(oldMessages)
-
-	// Build the user-facing prompt: conversation text + summary instructions.
-	userPrompt := opts.SummaryPrompt
-	if userPrompt == "" {
-		userPrompt = defaultSummaryPrompt
-	}
-	if customInstructions != "" {
-		userPrompt += "\n\nAdditional instructions: " + customInstructions
+	// Extract file operations from old messages.
+	ops := extractFileOps(oldMessages)
+	// Accumulate from previous compaction if present.
+	if prev != nil {
+		ops.mergeSlices(prev.ReadFiles, prev.ModifiedFiles)
 	}
+	// Also scan recent messages for file ops (they'll be carried forward).
+	recentOps := extractFileOps(recentMessages)
+	ops.merge(recentOps)
 
-	// Create a lightweight agent (no tools) just for summarisation.
-	summaryAgent := fantasy.NewAgent(model,
-		fantasy.WithSystemPrompt(defaultSystemPrompt),
-	)
-	result, err := summaryAgent.Generate(ctx, fantasy.AgentCall{
-		Prompt: conversationText + "\n\n" + userPrompt,
-	})
+	// Handle split turns: when the cut lands mid-turn, summarise the turn
+	// prefix separately and merge with the history summary.
+	var summaryText string
+	var err error
+
+	if IsSplitTurn(messages, cutPoint) {
+		summaryText, err = compactSplitTurn(ctx, model, oldMessages, messages, cutPoint, opts, customInstructions)
+	} else {
+		summaryText, err = compactNormal(ctx, model, oldMessages, opts, customInstructions)
+	}
 	if err != nil {
-		return nil, nil, fmt.Errorf("compaction summarisation failed: %w", err)
+		return nil, nil, err
 	}
 
-	summaryText := result.Response.Content.Text()
 	if summaryText == "" {
 		return nil, nil, fmt.Errorf("compaction produced an empty summary")
 	}
@@ -338,5 +520,120 @@ func Compact(
 		OriginalTokens:  originalTokens,
 		CompactedTokens: compactedTokens,
 		MessagesRemoved: len(oldMessages),
+		CutPoint:        cutPoint,
+		ReadFiles:       sortedKeys(ops.ReadFiles),
+		ModifiedFiles:   sortedKeys(ops.ModifiedFiles),
 	}, newMessages, nil
 }
+
+// compactNormal generates a summary for a clean turn-boundary cut.
+func compactNormal(
+	ctx context.Context,
+	model fantasy.LanguageModel,
+	oldMessages []fantasy.Message,
+	opts CompactionOptions,
+	customInstructions string,
+) (string, error) {
+	conversationText := serializeMessages(oldMessages)
+	return generateSummary(ctx, model, conversationText, opts, customInstructions)
+}
+
+// compactSplitTurn handles the case where the cut point lands mid-turn.
+// It generates two summaries and merges them:
+//  1. History summary: all complete turns before the split turn
+//  2. Turn prefix summary: the early part of the split turn (from the turn's
+//     user message up to the cut point)
+//
+// The merged result preserves context from both the older history and the
+// beginning of the current long turn.
+func compactSplitTurn(
+	ctx context.Context,
+	model fantasy.LanguageModel,
+	oldMessages []fantasy.Message,
+	allMessages []fantasy.Message,
+	cutPoint int,
+	opts CompactionOptions,
+	customInstructions string,
+) (string, error) {
+	// Find where the split turn starts.
+	turnStart := findTurnStart(allMessages, cutPoint)
+
+	// Messages before the turn are the "history" portion.
+	historyMessages := oldMessages
+	if turnStart > 0 && turnStart < len(oldMessages) {
+		historyMessages = oldMessages[:turnStart]
+	}
+
+	// The turn prefix: from turnStart to cutPoint.
+	turnPrefixMessages := allMessages[turnStart:cutPoint]
+
+	var historySummary string
+	var err error
+
+	// Generate history summary if there are complete turns before the split.
+	if len(historyMessages) >= 2 {
+		historySummary, err = generateSummary(ctx, model,
+			serializeMessages(historyMessages), opts, "")
+		if err != nil {
+			return "", fmt.Errorf("split turn history summary failed: %w", err)
+		}
+	}
+
+	// Generate turn prefix summary.
+	turnPrefixText := serializeMessages(turnPrefixMessages)
+	turnPrefixPrompt := "The messages above are the BEGINNING of a long turn that was split. " +
+		"Summarize the work done so far in this turn, preserving tool call results, " +
+		"file changes, and progress. Another LLM will continue this turn."
+	if customInstructions != "" {
+		turnPrefixPrompt += "\n\nAdditional instructions: " + customInstructions
+	}
+
+	summaryAgent := fantasy.NewAgent(model,
+		fantasy.WithSystemPrompt(defaultSystemPrompt),
+	)
+	result, err := summaryAgent.Generate(ctx, fantasy.AgentCall{
+		Prompt: turnPrefixText + "\n\n" + turnPrefixPrompt,
+	})
+	if err != nil {
+		return "", fmt.Errorf("split turn prefix summary failed: %w", err)
+	}
+	turnPrefixSummary := result.Response.Content.Text()
+
+	// Merge the two summaries.
+	if historySummary != "" && turnPrefixSummary != "" {
+		return historySummary + "\n\n---\n\n## Current Turn (in progress)\n\n" + turnPrefixSummary, nil
+	}
+	if turnPrefixSummary != "" {
+		return turnPrefixSummary, nil
+	}
+	return historySummary, nil
+}
+
+// generateSummary calls the LLM to produce a structured summary.
+func generateSummary(
+	ctx context.Context,
+	model fantasy.LanguageModel,
+	conversationText string,
+	opts CompactionOptions,
+	customInstructions string,
+) (string, error) {
+	userPrompt := opts.SummaryPrompt
+	if userPrompt == "" {
+		userPrompt = defaultSummaryPrompt
+	}
+	if customInstructions != "" {
+		userPrompt += "\n\nAdditional instructions: " + customInstructions
+	}
+
+	summaryAgent := fantasy.NewAgent(model,
+		fantasy.WithSystemPrompt(defaultSystemPrompt),
+	)
+	result, err := summaryAgent.Generate(ctx, fantasy.AgentCall{
+		Prompt: conversationText + "\n\n" + userPrompt,
+	})
+	if err != nil {
+		return "", fmt.Errorf("compaction summarisation failed: %w", err)
+	}
+
+	return result.Response.Content.Text(), nil
+}

internal/compaction/compaction_test.go

@@ -243,7 +243,7 @@ func TestCompact_TooFewMessages(t *testing.T) {
 		makeTextMessageN(fantasy.MessageRoleUser, 400),
 	}
 
-	result, newMsgs, err := Compact(context.TODO(), nil, msgs, CompactionOptions{}, "")
+	result, newMsgs, err := Compact(context.TODO(), nil, msgs, CompactionOptions{}, "", nil)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -262,7 +262,7 @@ func TestCompact_WithinBudget(t *testing.T) {
 		makeTextMessageN(fantasy.MessageRoleAssistant, 400),
 	}
 
-	result, newMsgs, err := Compact(context.TODO(), nil, msgs, CompactionOptions{}, "")
+	result, newMsgs, err := Compact(context.TODO(), nil, msgs, CompactionOptions{}, "", nil)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -273,3 +273,169 @@ func TestCompact_WithinBudget(t *testing.T) {
 		t.Errorf("messages changed: got %d, want %d", len(newMsgs), len(msgs))
 	}
 }
+
+// ---------------------------------------------------------------------------
+// Tool result truncation
+// ---------------------------------------------------------------------------
+
+func TestTruncateToolResult(t *testing.T) {
+	// Short text — no truncation.
+	short := strings.Repeat("x", 100)
+	if got := truncateToolResult(short); got != short {
+		t.Errorf("truncated short text unexpectedly")
+	}
+
+	// Exactly at limit.
+	exact := strings.Repeat("x", maxToolResultChars)
+	if got := truncateToolResult(exact); got != exact {
+		t.Errorf("truncated text at exact limit")
+	}
+
+	// Over limit.
+	over := strings.Repeat("x", maxToolResultChars+500)
+	got := truncateToolResult(over)
+	if len(got) > maxToolResultChars+50 { // allow room for marker
+		t.Errorf("truncated text too long: %d chars", len(got))
+	}
+	if !strings.Contains(got, "500 chars truncated") {
+		t.Errorf("truncation marker missing, got: %s", got[maxToolResultChars:])
+	}
+}
+
+func TestSerializeMessages_TruncatesToolResults(t *testing.T) {
+	longResult := strings.Repeat("R", maxToolResultChars+1000)
+	msgs := []fantasy.Message{
+		makeTextMessage(fantasy.MessageRoleUser, "question"),
+		{
+			Role:    fantasy.MessageRoleTool,
+			Content: []fantasy.MessagePart{fantasy.TextPart{Text: longResult}},
+		},
+	}
+
+	serialized := serializeMessages(msgs)
+	if strings.Contains(serialized, longResult) {
+		t.Error("tool result was not truncated during serialisation")
+	}
+	if !strings.Contains(serialized, "chars truncated") {
+		t.Error("truncation marker missing in serialised output")
+	}
+}
+
+func TestSerializeMessages_PreservesNonToolText(t *testing.T) {
+	longText := strings.Repeat("T", maxToolResultChars+1000)
+	msgs := []fantasy.Message{
+		makeTextMessage(fantasy.MessageRoleUser, longText),
+	}
+
+	serialized := serializeMessages(msgs)
+	if !strings.Contains(serialized, longText) {
+		t.Error("non-tool text was unexpectedly truncated")
+	}
+}
+
+// ---------------------------------------------------------------------------
+// Split turn detection
+// ---------------------------------------------------------------------------
+
+func TestIsSplitTurn(t *testing.T) {
+	msgs := []fantasy.Message{
+		makeTextMessageN(fantasy.MessageRoleUser, 400),      // 0: turn 1 user
+		makeTextMessageN(fantasy.MessageRoleAssistant, 400), // 1: turn 1 assistant
+		makeTextMessageN(fantasy.MessageRoleUser, 400),      // 2: turn 2 user
+		makeTextMessageN(fantasy.MessageRoleAssistant, 400), // 3: turn 2 assistant
+		makeTextMessageN(fantasy.MessageRoleTool, 400),      // 4: turn 2 tool result
+		makeTextMessageN(fantasy.MessageRoleAssistant, 400), // 5: turn 2 assistant
+	}
+
+	tests := []struct {
+		name     string
+		cutPoint int
+		want     bool
+	}{
+		{"at user message (turn boundary)", 2, false},
+		{"at assistant mid-turn", 3, true},
+		{"at assistant after tool (mid-turn)", 5, true},
+		{"at 0 (no cut)", 0, false},
+		{"beyond range", 10, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := IsSplitTurn(msgs, tt.cutPoint)
+			if got != tt.want {
+				t.Errorf("IsSplitTurn(msgs, %d) = %v, want %v", tt.cutPoint, got, tt.want)
+			}
+		})
+	}
+}
+
+// ---------------------------------------------------------------------------
+// File operations extraction
+// ---------------------------------------------------------------------------
+
+func TestExtractFileOps(t *testing.T) {
+	// Create messages with tool calls.
+	msgs := []fantasy.Message{
+		{
+			Role: fantasy.MessageRoleAssistant,
+			Content: []fantasy.MessagePart{
+				fantasy.ToolCallPart{ToolCallID: "1", ToolName: "read", Input: `{"path":"src/main.go"}`},
+				fantasy.ToolCallPart{ToolCallID: "2", ToolName: "write", Input: `{"path":"src/out.go"}`},
+				fantasy.ToolCallPart{ToolCallID: "3", ToolName: "edit", Input: `{"path":"src/edit.go"}`},
+				fantasy.ToolCallPart{ToolCallID: "4", ToolName: "grep", Input: `{"path":"src/search"}`},
+			},
+		},
+	}
+
+	ops := extractFileOps(msgs)
+	if !ops.ReadFiles["src/main.go"] {
+		t.Error("read file not tracked: src/main.go")
+	}
+	if !ops.ReadFiles["src/search"] {
+		t.Error("grep path not tracked as read: src/search")
+	}
+	if !ops.ModifiedFiles["src/out.go"] {
+		t.Error("write file not tracked: src/out.go")
+	}
+	if !ops.ModifiedFiles["src/edit.go"] {
+		t.Error("edit file not tracked: src/edit.go")
+	}
+}
+
+func TestFileOps_MergeSlices(t *testing.T) {
+	ops := newFileOps()
+	ops.ReadFiles["a.go"] = true
+	ops.ModifiedFiles["b.go"] = true
+
+	ops.mergeSlices(
+		[]string{"c.go", "a.go"},
+		[]string{"d.go"},
+	)
+
+	if len(ops.ReadFiles) != 2 { // a.go, c.go
+		t.Errorf("ReadFiles len = %d, want 2", len(ops.ReadFiles))
+	}
+	if len(ops.ModifiedFiles) != 2 { // b.go, d.go
+		t.Errorf("ModifiedFiles len = %d, want 2", len(ops.ModifiedFiles))
+	}
+}
+
+func TestSortedKeys(t *testing.T) {
+	m := map[string]bool{"c": true, "a": true, "b": true}
+	got := sortedKeys(m)
+	want := []string{"a", "b", "c"}
+	if len(got) != len(want) {
+		t.Fatalf("sortedKeys len = %d, want %d", len(got), len(want))
+	}
+	for i, v := range got {
+		if v != want[i] {
+			t.Errorf("sortedKeys[%d] = %q, want %q", i, v, want[i])
+		}
+	}
+}
+
+func TestSortedKeys_Empty(t *testing.T) {
+	got := sortedKeys(nil)
+	if got != nil {
+		t.Errorf("sortedKeys(nil) = %v, want nil", got)
+	}
+}

internal/config/config.go

@@ -157,6 +157,32 @@ type Theme struct {
 	Markdown MarkdownThemeConfig `json:"markdown,omitzero" yaml:"markdown,omitempty"`
 }
 
+// CustomModelConfig defines a custom model that can be used with custom/custom
+// or other custom/ prefixed models. These models are loaded from the config file
+// and merged into the custom provider in the model registry.
+type CustomModelConfig struct {
+	Name        string      `json:"name" yaml:"name"`
+	Family      string      `json:"family,omitempty" yaml:"family,omitempty"`
+	Attachment  bool        `json:"attachment,omitempty" yaml:"attachment,omitempty"`
+	Reasoning   bool        `json:"reasoning,omitempty" yaml:"reasoning,omitempty"`
+	Temperature bool        `json:"temperature,omitempty" yaml:"temperature,omitempty"`
+	Knowledge   string      `json:"knowledge,omitempty" yaml:"knowledge,omitempty"`
+	Cost        CostConfig  `json:"cost" yaml:"cost"`
+	Limit       LimitConfig `json:"limit" yaml:"limit"`
+}
+
+// CostConfig defines the pricing for a custom model.
+type CostConfig struct {
+	Input  float64 `json:"input" yaml:"input"`
+	Output float64 `json:"output" yaml:"output"`
+}
+
+// LimitConfig defines context and output limits for a custom model.
+type LimitConfig struct {
+	Context int `json:"context" yaml:"context"`
+	Output  int `json:"output" yaml:"output"`
+}
+
 // Config represents the complete application configuration including MCP servers,
 // model settings, UI preferences, and API credentials. It supports both command-line
 // flags and configuration file settings.
@@ -183,6 +209,13 @@ type Config struct {
 
 	// TLS configuration
 	TLSSkipVerify bool `json:"tls-skip-verify,omitempty" yaml:"tls-skip-verify,omitempty"`
+
+	// Prompt templates configuration
+	Prompts           []string `json:"prompts,omitempty" yaml:"prompts,omitempty"`
+	NoPromptTemplates bool     `json:"no-prompt-templates,omitempty" yaml:"no-prompt-templates,omitempty"`
+
+	// Custom model definitions (under custom/ provider)
+	CustomModels map[string]CustomModelConfig `json:"customModels,omitempty" yaml:"customModels,omitempty"`
 }
 
 // GetTransportType returns the transport type for the server config, mapping

internal/core/bash.go

@@ -1,16 +1,41 @@
 package core
 
 import (
-	"bytes"
+	"bufio"
 	"context"
 	"fmt"
+	"io"
+	"os"
 	"os/exec"
 	"strings"
+	"sync"
 	"time"
 
 	"charm.land/fantasy"
 )
 
+// ToolOutputCallback is the signature for streaming tool output.
+// It receives tool call ID, tool name, output chunk, and whether it's stderr.
+type ToolOutputCallback func(toolCallID, toolName, chunk string, isStderr bool)
+
+// contextKey is a custom type for context keys to avoid collisions.
+type contextKey string
+
+const toolOutputCallbackKey contextKey = "toolOutputCallback"
+
+// ContextWithToolOutputCallback returns a new context with the tool output callback set.
+func ContextWithToolOutputCallback(ctx context.Context, callback ToolOutputCallback) context.Context {
+	return context.WithValue(ctx, toolOutputCallbackKey, callback)
+}
+
+// toolOutputCallbackFromContext retrieves the tool output callback from context.
+func toolOutputCallbackFromContext(ctx context.Context) ToolOutputCallback {
+	if cb, ok := ctx.Value(toolOutputCallbackKey).(ToolOutputCallback); ok {
+		return cb
+	}
+	return nil
+}
+
 const defaultBashTimeout = 120 * time.Second
 const maxBashTimeout = 600 * time.Second
 
@@ -90,32 +115,165 @@ func executeBash(ctx context.Context, call fantasy.ToolCall, workDir string) (fa
 		cmd.Dir = workDir
 	}
 
-	var stdout, stderr bytes.Buffer
-	cmd.Stdout = &stdout
-	cmd.Stderr = &stderr
+	// Ensure SHELL is set to bash so child processes (e.g. tmux) use bash
+	// rather than the user's login shell (which may be nushell, fish, etc.).
+	bashPath, err := exec.LookPath("bash")
+	if err != nil {
+		bashPath = "/bin/bash"
+	}
+	cmd.Env = append(os.Environ(), "SHELL="+bashPath)
 
-	err := cmd.Run()
+	// Get the output callback if present (for streaming support)
+	outputCallback := toolOutputCallbackFromContext(ctx)
+
+	if outputCallback != nil {
+		// Streaming mode: use pipes to capture output as it arrives
+		return executeBashStreaming(cmdCtx, call, cmd, outputCallback)
+	}
+
+	// Non-streaming mode: collect all output at once (original behavior)
+	return executeBashBuffered(cmdCtx, call, cmd)
+}
+
+// executeBashBuffered collects all output before returning (original behavior).
+// It uses explicit pipes (not cmd.Stdout) so that cmd.WaitDelay can forcibly
+// close them when grandchild processes hold pipe handles open after the
+// direct child exits.
+func executeBashBuffered(cmdCtx context.Context, call fantasy.ToolCall, cmd *exec.Cmd) (fantasy.ToolResponse, error) {
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return fantasy.NewTextErrorResponse("failed to create stdout pipe"), nil
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return fantasy.NewTextErrorResponse("failed to create stderr pipe"), nil
+	}
+
+	if err := cmd.Start(); err != nil {
+		return fantasy.NewTextErrorResponse(fmt.Sprintf("failed to start command: %v", err)), nil
+	}
+
+	// Read pipes concurrently
+	var wg sync.WaitGroup
+	var stdout, stderr strings.Builder
+	var stdoutErr, stderrErr error
+
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		_, stdoutErr = io.Copy(&stdout, stdoutPipe)
+	}()
+	go func() {
+		defer wg.Done()
+		_, stderrErr = io.Copy(&stderr, stderrPipe)
+	}()
+
+	// Wait for the process to exit first. cmd.WaitDelay ensures that if
+	// pipes remain open (held by grandchild processes), they'll be forcibly
+	// closed after the grace period, which unblocks the io.Copy goroutines.
+	waitErr := cmd.Wait()
+
+	// Wait for pipe readers to finish draining.
+	wg.Wait()
+
+	// Ignore pipe read errors caused by WaitDelay force-closing —
+	// we still have whatever was read before the close.
+	_ = stdoutErr
+	_ = stderrErr
+
+	exitCode := 0
+	if waitErr != nil {
+		if exitErr, ok := waitErr.(*exec.ExitError); ok {
+			exitCode = exitErr.ExitCode()
+		} else if cmdCtx.Err() == context.DeadlineExceeded {
+			return fantasy.NewTextErrorResponse("command timed out"), nil
+		}
+	}
+
+	return buildBashResponse(stdout.String(), stderr.String(), exitCode)
+}
+
+// executeBashStreaming streams output as it arrives via the callback.
+func executeBashStreaming(cmdCtx context.Context, call fantasy.ToolCall, cmd *exec.Cmd, outputCallback ToolOutputCallback) (fantasy.ToolResponse, error) {
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return fantasy.NewTextErrorResponse("failed to create stdout pipe"), nil
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return fantasy.NewTextErrorResponse("failed to create stderr pipe"), nil
+	}
+
+	// Start command execution
+	if err := cmd.Start(); err != nil {
+		return fantasy.NewTextErrorResponse(fmt.Sprintf("failed to start command: %v", err)), nil
+	}
+
+	// Stream stdout and stderr concurrently
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+	var stdoutChunks, stderrChunks []string
+
+	streamOutput := func(reader io.Reader, isStderr bool) {
+		defer wg.Done()
+		scanner := bufio.NewScanner(reader)
+		// Use larger buffer for long lines
+		buf := make([]byte, 0, 64*1024)
+		scanner.Buffer(buf, 1024*1024)
+
+		for scanner.Scan() {
+			chunk := scanner.Text()
+			// Send chunk to UI
+			outputCallback(call.ID, "bash", chunk, isStderr)
+			// Collect for final result
+			mu.Lock()
+			if isStderr {
+				stderrChunks = append(stderrChunks, chunk)
+			} else {
+				stdoutChunks = append(stdoutChunks, chunk)
+			}
+			mu.Unlock()
+		}
+	}
+
+	wg.Add(2)
+	go streamOutput(stdoutPipe, false)
+	go streamOutput(stderrPipe, true)
+
+	// Wait for the process to exit. cmd.WaitDelay ensures that if pipes
+	// remain open (held by grandchild processes), they'll be forcibly closed
+	// after the grace period, which unblocks the scanners above.
+	err = cmd.Wait()
+
+	// Wait for the pipe readers to finish draining. This will complete
+	// quickly since cmd.Wait() (with WaitDelay) has already ensured
+	// the pipes are closed.
+	wg.Wait()
 
 	exitCode := 0
 	if err != nil {
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			exitCode = exitErr.ExitCode()
 		} else if cmdCtx.Err() == context.DeadlineExceeded {
-			return fantasy.NewTextErrorResponse(fmt.Sprintf("command timed out after %v", timeout)), nil
+			return fantasy.NewTextErrorResponse("command timed out"), nil
 		}
 	}
 
-	// Build result
+	return buildBashResponse(strings.Join(stdoutChunks, "\n"), strings.Join(stderrChunks, "\n"), exitCode)
+}
+
+// buildBashResponse constructs the final tool response from stdout/stderr.
+func buildBashResponse(stdout, stderr string, exitCode int) (fantasy.ToolResponse, error) {
 	var result strings.Builder
-	if stdout.Len() > 0 {
-		result.WriteString(stdout.String())
+	if stdout != "" {
+		result.WriteString(stdout)
 	}
-	if stderr.Len() > 0 {
+	if stderr != "" {
 		if result.Len() > 0 {
 			result.WriteString("\n")
 		}
 		result.WriteString("STDERR:\n")
-		result.WriteString(stderr.String())
+		result.WriteString(stderr)
 	}
 	if exitCode != 0 {
 		if result.Len() > 0 {

internal/core/bash_test.go

@@ -0,0 +1,129 @@
+package core
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"charm.land/fantasy"
+)
+
+// helper to create a bash tool call with the given command and optional timeout.
+func bashCall(command string, timeout float64) fantasy.ToolCall {
+	args := map[string]any{"command": command}
+	if timeout > 0 {
+		args["timeout"] = timeout
+	}
+	input, _ := json.Marshal(args)
+	return fantasy.ToolCall{
+		ID:    "test-call",
+		Name:  "bash",
+		Input: string(input),
+	}
+}
+
+func TestBash_SimpleCommand(t *testing.T) {
+	resp, err := executeBash(context.Background(), bashCall("echo hello", 0), "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("expected success, got error: %s", resp.Content)
+	}
+	if resp.Content != "hello\n" {
+		t.Errorf("expected 'hello\\n', got %q", resp.Content)
+	}
+}
+
+func TestBash_TimeoutKillsProcess(t *testing.T) {
+	start := time.Now()
+	resp, err := executeBash(context.Background(), bashCall("sleep 60", 2), "")
+	elapsed := time.Since(start)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !resp.IsError {
+		t.Fatal("expected error response for timed-out command")
+	}
+	if elapsed > 10*time.Second {
+		t.Errorf("command took %v, expected ~2s timeout", elapsed)
+	}
+}
+
+func TestBash_BackgroundProcessDoesNotHang(t *testing.T) {
+	// This command spawns a background sleep that would hold pipes open
+	// forever if we didn't have process group killing + WaitDelay.
+	start := time.Now()
+	resp, err := executeBash(context.Background(), bashCall("echo done; sleep 3600 &", 5), "")
+	elapsed := time.Since(start)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	// The foreground command (echo) should complete quickly
+	if elapsed > 5*time.Second {
+		t.Errorf("command took %v, should complete in <5s (background process should not block)", elapsed)
+	}
+	if resp.IsError {
+		t.Fatalf("expected success, got error: %s", resp.Content)
+	}
+}
+
+func TestBash_BackgroundProcessDoesNotHang_Streaming(t *testing.T) {
+	// Same test but in streaming mode (with output callback).
+	ctx := ContextWithToolOutputCallback(context.Background(), func(_, _, _ string, _ bool) {})
+	start := time.Now()
+	resp, err := executeBash(ctx, bashCall("echo streaming; sleep 3600 &", 5), "")
+	elapsed := time.Since(start)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if elapsed > 5*time.Second {
+		t.Errorf("streaming command took %v, should complete in <5s", elapsed)
+	}
+	if resp.IsError {
+		t.Fatalf("expected success, got error: %s", resp.Content)
+	}
+}
+
+func TestBash_ContextCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		_, _ = executeBash(ctx, bashCall("sleep 60", 0), "")
+	}()
+
+	// Cancel after a short delay
+	time.Sleep(500 * time.Millisecond)
+	cancel()
+
+	// Should return promptly after cancellation
+	select {
+	case <-done:
+		// success
+	case <-time.After(5 * time.Second):
+		t.Fatal("executeBash did not return after context cancellation")
+	}
+}
+
+func TestBash_BannedCommand(t *testing.T) {
+	resp, err := executeBash(context.Background(), bashCall("alias foo=bar", 0), "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !resp.IsError {
+		t.Fatal("expected error for banned command")
+	}
+}
+
+func TestBash_EmptyCommand(t *testing.T) {
+	resp, err := executeBash(context.Background(), bashCall("", 0), "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !resp.IsError {
+		t.Fatal("expected error for empty command")
+	}
+}

internal/core/edit.go

@@ -6,8 +6,11 @@ import (
 	"os"
 	"strings"
 	"unicode"
+	"unicode/utf8"
 
 	"charm.land/fantasy"
+
+	udiff "github.com/aymanbagabas/go-udiff"
 )
 
 type editArgs struct {
@@ -82,7 +85,7 @@ func executeEdit(ctx context.Context, call fantasy.ToolCall, workDir string) (fa
 			if err := os.WriteFile(absPath, []byte(newContent), 0644); err != nil {
 				return fantasy.NewTextErrorResponse(fmt.Sprintf("failed to write file: %v", err)), nil
 			}
-			diff := generateDiff(absPath, normalized, newContent, idx)
+			diff := generateDiff(absPath, normalized, newContent)
 			resp := fantasy.NewTextResponse(fmt.Sprintf("Applied edit (fuzzy match) to %s\n%s", args.Path, diff))
 			return fantasy.WithResponseMetadata(resp, editDiffMeta(absPath, matchedText, args.NewText)), nil
 		}
@@ -100,8 +103,7 @@ func executeEdit(ctx context.Context, call fantasy.ToolCall, workDir string) (fa
 		return fantasy.NewTextErrorResponse(fmt.Sprintf("failed to write file: %v", err)), nil
 	}
 
-	idx := strings.Index(normalized, normalizedOld)
-	diff := generateDiff(absPath, normalized, newContent, idx)
+	diff := generateDiff(absPath, normalized, newContent)
 	resp := fantasy.NewTextResponse(fmt.Sprintf("Applied edit to %s\n%s", args.Path, diff))
 	return fantasy.WithResponseMetadata(resp, editDiffMeta(absPath, normalizedOld, args.NewText)), nil
 }
@@ -122,102 +124,108 @@ func editDiffMeta(path, oldText, newText string) map[string]any {
 }
 
 // fuzzyMatch tries to find old_text with relaxed matching:
-// - Strips trailing whitespace per line
-// - Normalizes unicode quotes to ASCII
-// - Normalizes unicode dashes/spaces
-// Returns (index, matchLength) or (-1, 0) if not found.
+//   - Strips trailing whitespace per line
+//   - Normalizes unicode quotes to ASCII
+//   - Normalizes unicode dashes/spaces
+//
+// Returns (index, matchLength) in the original content, or (-1, 0) if not
+// found or ambiguous (multiple matches).
 func fuzzyMatch(content, search string) (int, int) {
-	normalizedContent := normalizeForFuzzy(content)
-	normalizedSearch := normalizeForFuzzy(search)
+	normContent, contentMap := normalizeWithMap(content)
+	normSearch := normalizeForFuzzy(search)
 
-	idx := strings.Index(normalizedContent, normalizedSearch)
+	if normSearch == "" {
+		return -1, 0
+	}
+
+	idx := strings.Index(normContent, normSearch)
 	if idx < 0 {
 		return -1, 0
 	}
 
-	// Map back to original content position
-	// Since normalization can change lengths, we need to find the
-	// corresponding region in the original content
-	origIdx := mapFuzzyIndex(content, normalizedContent, idx)
-	origEnd := mapFuzzyIndex(content, normalizedContent, idx+len(normalizedSearch))
+	// Reject ambiguous matches — if there are multiple fuzzy matches
+	// we can't safely pick one.
+	if strings.Count(normContent, normSearch) > 1 {
+		return -1, 0
+	}
 
-	return origIdx, origEnd - origIdx
+	// Map normalized byte positions back to original byte positions.
+	origStart := contentMap[idx]
+	endNorm := idx + len(normSearch)
+	var origEnd int
+	if endNorm >= len(normContent) {
+		origEnd = len(content)
+	} else {
+		origEnd = contentMap[endNorm]
+	}
+
+	return origStart, origEnd - origStart
 }
 
-func normalizeForFuzzy(s string) string {
-	// Strip trailing whitespace per line
+// normalizeWithMap normalizes s for fuzzy matching and returns both the
+// normalized string and a byte-position mapping where mapping[i] is the
+// original byte position corresponding to normalized byte position i.
+//
+// Normalization: trim trailing whitespace per line, replace unicode
+// quotes/dashes/spaces with their ASCII equivalents.
+func normalizeWithMap(s string) (string, []int) {
+	var result []byte
+	var mapping []int // mapping[i] = original byte position for result byte i
+
 	lines := strings.Split(s, "\n")
-	for i, line := range lines {
-		lines[i] = strings.TrimRightFunc(line, unicode.IsSpace)
-	}
-	result := strings.Join(lines, "\n")
-
-	// Normalize smart quotes
-	replacer := strings.NewReplacer(
-		"\u201c", "\"", // left double quote
-		"\u201d", "\"", // right double quote
-		"\u2018", "'", // left single quote
-		"\u2019", "'", // right single quote
-		"\u2013", "-", // en dash
-		"\u2014", "-", // em dash
-		"\u00a0", " ", // non-breaking space
-	)
-	return replacer.Replace(result)
-}
-
-func mapFuzzyIndex(original, normalized string, normIdx int) int {
-	// Simple approach: count runes up to normIdx in normalized,
-	// then advance that many runes in original.
-	// This works because our normalization only replaces runes 1:1.
-	origRunes := []rune(original)
-	normRunes := []rune(normalized)
-
-	if normIdx >= len(normRunes) {
-		return len(original)
-	}
-
-	// Count bytes for the first normIdx runes in original
-	byteCount := 0
-	for i := 0; i < normIdx && i < len(origRunes); i++ {
-		byteCount += len(string(origRunes[i]))
-	}
-	return byteCount
-}
-
-// generateDiff creates a simple unified diff showing the change.
-func generateDiff(path, old, new string, changeIdx int) string {
-	oldLines := strings.Split(old, "\n")
-	newLines := strings.Split(new, "\n")
-
-	// Find the line number where the change starts
-	lineNum := strings.Count(old[:changeIdx], "\n") + 1
-
-	// Show context around the change
-	contextLines := 3
-	start := max(lineNum-contextLines-1, 0)
-
-	var diff strings.Builder
-	fmt.Fprintf(&diff, "--- %s\n+++ %s\n", path, path)
-
-	// Find changed region
-	endOld := min(lineNum+contextLines+countNewlines(old[changeIdx:])+1, len(oldLines))
-	endNew := min(lineNum+contextLines+countNewlines(new[changeIdx:])+1, len(newLines))
-
-	fmt.Fprintf(&diff, "@@ -%d,%d +%d,%d @@\n", start+1, endOld-start, start+1, endNew-start)
-
-	// Very simplified diff: show old lines as removed, new lines as added
-	// around the change region
-	for i := start; i < endOld && i < len(oldLines); i++ {
-		prefix := " "
-		if i >= lineNum-1 && i < lineNum-1+countNewlines(old[changeIdx:])+1 {
-			prefix = "-"
+	origPos := 0
+	for li, line := range lines {
+		if li > 0 {
+			result = append(result, '\n')
+			mapping = append(mapping, origPos)
+			origPos++ // skip \n in original
 		}
-		fmt.Fprintf(&diff, "%s %s\n", prefix, oldLines[i])
+
+		trimmed := strings.TrimRightFunc(line, unicode.IsSpace)
+
+		for j := 0; j < len(trimmed); {
+			r, size := utf8.DecodeRuneInString(trimmed[j:])
+			repl := normalizeRune(r)
+			for k := 0; k < len(repl); k++ {
+				mapping = append(mapping, origPos+j)
+			}
+			result = append(result, repl...)
+			j += size
+		}
+
+		origPos += len(line) // advance past full original line including trailing ws
 	}
 
-	return diff.String()
+	return string(result), mapping
 }
 
-func countNewlines(s string) int {
-	return strings.Count(s, "\n")
+// normalizeRune maps unicode quotes, dashes, and non-breaking spaces to
+// their ASCII equivalents. Returns the original rune as a string for all
+// other characters.
+func normalizeRune(r rune) string {
+	switch r {
+	case '\u201c', '\u201d': // left/right double quote
+		return "\""
+	case '\u2018', '\u2019': // left/right single quote
+		return "'"
+	case '\u2013', '\u2014': // en dash, em dash
+		return "-"
+	case '\u00a0': // non-breaking space
+		return " "
+	default:
+		return string(r)
+	}
+}
+
+// normalizeForFuzzy normalizes s for fuzzy matching (without position mapping).
+// Used for the search string where position mapping is not needed.
+func normalizeForFuzzy(s string) string {
+	norm, _ := normalizeWithMap(s)
+	return norm
+}
+
+// generateDiff creates a unified diff showing the change between old and new
+// file contents. Uses the go-udiff library for correct diff computation.
+func generateDiff(path, old, new string) string {
+	return udiff.Unified(path, path, old, new)
 }

internal/core/edit_test.go

@@ -0,0 +1,717 @@
+package core
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"charm.land/fantasy"
+)
+
+func writeFileOrFail(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatalf("failed to write test file %s: %v", path, err)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// fuzzyMatch — the core bug fix
+// ---------------------------------------------------------------------------
+
+func TestFuzzyMatch_TrailingWhitespace(t *testing.T) {
+	// The original bug: trailing whitespace on lines caused mapFuzzyIndex
+	// to return wrong byte positions, corrupting the replacement splice.
+	content := "line1   \nline2   \nline3   \nTAIL\n"
+	search := "line2\nline3"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match, got none")
+	}
+
+	matched := content[idx : idx+matchLen]
+	want := "line2   \nline3   "
+	if matched != want {
+		t.Errorf("matched=%q, want=%q", matched, want)
+	}
+
+	// Verify replacement is correct
+	repl := content[:idx] + "REPLACED" + content[idx+matchLen:]
+	wantRepl := "line1   \nREPLACED\nTAIL\n"
+	if repl != wantRepl {
+		t.Errorf("replacement=%q, want=%q", repl, wantRepl)
+	}
+}
+
+func TestFuzzyMatch_TrailingWhitespace_FirstLine(t *testing.T) {
+	content := "line1   \nline2   \nline3\n"
+	search := "line1\nline2"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match")
+	}
+
+	matched := content[idx : idx+matchLen]
+	want := "line1   \nline2   "
+	if matched != want {
+		t.Errorf("matched=%q, want=%q", matched, want)
+	}
+}
+
+func TestFuzzyMatch_TrailingWhitespace_LastLine(t *testing.T) {
+	content := "HEAD\nline1   \nline2   \n"
+	search := "line1\nline2"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match")
+	}
+
+	matched := content[idx : idx+matchLen]
+	want := "line1   \nline2   "
+	if matched != want {
+		t.Errorf("matched=%q, want=%q", matched, want)
+	}
+}
+
+func TestFuzzyMatch_TrailingWhitespace_AtEOF(t *testing.T) {
+	// Match extends to the very end of the content
+	content := "HEAD\nline1   \nline2   "
+	search := "line1\nline2"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match")
+	}
+
+	matched := content[idx : idx+matchLen]
+	want := "line1   \nline2   "
+	if matched != want {
+		t.Errorf("matched=%q, want=%q", matched, want)
+	}
+}
+
+func TestFuzzyMatch_UnicodeQuotes(t *testing.T) {
+	content := "say \u201chello\u201d\n"
+	search := "say \"hello\"\n"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match for unicode quotes")
+	}
+
+	matched := content[idx : idx+matchLen]
+	if matched != content { // entire content should match
+		t.Errorf("matched=%q, want=%q", matched, content)
+	}
+}
+
+func TestFuzzyMatch_SmartSingleQuotes(t *testing.T) {
+	content := "it\u2019s a test\n"
+	search := "it's a test\n"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match for smart single quotes")
+	}
+	matched := content[idx : idx+matchLen]
+	if matched != content {
+		t.Errorf("matched=%q, want=%q", matched, content)
+	}
+}
+
+func TestFuzzyMatch_EmDash(t *testing.T) {
+	content := "foo \u2014 bar\n"
+	search := "foo - bar\n"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match for em dash")
+	}
+	matched := content[idx : idx+matchLen]
+	if matched != content {
+		t.Errorf("matched=%q, want=%q", matched, content)
+	}
+}
+
+func TestFuzzyMatch_NonBreakingSpace(t *testing.T) {
+	content := "hello\u00a0world\n"
+	search := "hello world\n"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match for non-breaking space")
+	}
+	matched := content[idx : idx+matchLen]
+	if matched != content {
+		t.Errorf("matched=%q, want=%q", matched, content)
+	}
+}
+
+func TestFuzzyMatch_NoMatch(t *testing.T) {
+	content := "hello world\n"
+	search := "goodbye world\n"
+
+	idx, _ := fuzzyMatch(content, search)
+	if idx >= 0 {
+		t.Error("expected no match")
+	}
+}
+
+func TestFuzzyMatch_AmbiguousReturnsNoMatch(t *testing.T) {
+	// Two identical blocks — fuzzy match should refuse to pick one
+	content := "block\nblock\n"
+	search := "block"
+
+	idx, _ := fuzzyMatch(content, search)
+	if idx >= 0 {
+		t.Error("expected no match for ambiguous fuzzy hit")
+	}
+}
+
+func TestFuzzyMatch_EmptySearch(t *testing.T) {
+	idx, _ := fuzzyMatch("content", "")
+	if idx >= 0 {
+		t.Error("expected no match for empty search")
+	}
+}
+
+func TestFuzzyMatch_MultiLineWithMixedWhitespace(t *testing.T) {
+	content := "func foo() {\t  \n\treturn 1  \n}\t \n"
+	search := "func foo() {\n\treturn 1\n}"
+
+	idx, matchLen := fuzzyMatch(content, search)
+	if idx < 0 {
+		t.Fatal("expected fuzzy match")
+	}
+
+	// Replacement should preserve surrounding content
+	repl := content[:idx] + "func bar() {\n\treturn 2\n}" + content[idx+matchLen:]
+	if !strings.HasPrefix(repl, "func bar()") {
+		t.Errorf("unexpected replacement start: %q", repl[:20])
+	}
+	if !strings.HasSuffix(repl, "\n") {
+		t.Errorf("replacement should end with newline: %q", repl)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// normalizeWithMap — position mapping correctness
+// ---------------------------------------------------------------------------
+
+func TestNormalizeWithMap_NoTrailingWhitespace(t *testing.T) {
+	s := "abc\ndef"
+	norm, mapping := normalizeWithMap(s)
+	if norm != s {
+		t.Errorf("norm=%q, want=%q", norm, s)
+	}
+	// Each byte should map to itself
+	for i, orig := range mapping {
+		if orig != i {
+			t.Errorf("mapping[%d]=%d, want=%d", i, orig, i)
+		}
+	}
+}
+
+func TestNormalizeWithMap_TrailingWhitespace(t *testing.T) {
+	s := "ab   \ncd"
+	norm, mapping := normalizeWithMap(s)
+	wantNorm := "ab\ncd"
+	if norm != wantNorm {
+		t.Errorf("norm=%q, want=%q", norm, wantNorm)
+	}
+	// 'a'→0, 'b'→1, '\n'→5, 'c'→6, 'd'→7
+	wantMapping := []int{0, 1, 5, 6, 7}
+	if len(mapping) != len(wantMapping) {
+		t.Fatalf("mapping len=%d, want=%d", len(mapping), len(wantMapping))
+	}
+	for i, want := range wantMapping {
+		if mapping[i] != want {
+			t.Errorf("mapping[%d]=%d, want=%d", i, mapping[i], want)
+		}
+	}
+}
+
+func TestNormalizeWithMap_UnicodeReplacement(t *testing.T) {
+	// \u201c is 3 bytes in UTF-8, replaced with " which is 1 byte
+	s := "\u201chello\u201d"
+	norm, mapping := normalizeWithMap(s)
+	wantNorm := "\"hello\""
+	if norm != wantNorm {
+		t.Errorf("norm=%q, want=%q", norm, wantNorm)
+	}
+	// " maps to byte 0 (start of \u201c), h maps to 3, e→4, l→5, l→6, o→7, " maps to 8 (start of \u201d)
+	wantMapping := []int{0, 3, 4, 5, 6, 7, 8}
+	if len(mapping) != len(wantMapping) {
+		t.Fatalf("mapping len=%d, want=%d", len(mapping), len(wantMapping))
+	}
+	for i, want := range wantMapping {
+		if mapping[i] != want {
+			t.Errorf("mapping[%d]=%d, want=%d", i, mapping[i], want)
+		}
+	}
+}
+
+func TestNormalizeWithMap_EmptyString(t *testing.T) {
+	norm, mapping := normalizeWithMap("")
+	if norm != "" {
+		t.Errorf("norm=%q, want empty", norm)
+	}
+	if len(mapping) != 0 {
+		t.Errorf("mapping len=%d, want 0", len(mapping))
+	}
+}
+
+func TestNormalizeWithMap_OnlyWhitespace(t *testing.T) {
+	norm, _ := normalizeWithMap("   \n   ")
+	if norm != "\n" {
+		t.Errorf("norm=%q, want %q", norm, "\n")
+	}
+}
+
+// ---------------------------------------------------------------------------
+// normalizeForFuzzy — consistency with normalizeWithMap
+// ---------------------------------------------------------------------------
+
+func TestNormalizeForFuzzy_ConsistentWithMap(t *testing.T) {
+	inputs := []string{
+		"hello   \nworld   ",
+		"\u201chello\u201d\u2014world",
+		"a\u00a0b\u2013c\n  trailing  \n",
+		"no changes here",
+		"",
+	}
+	for _, s := range inputs {
+		norm := normalizeForFuzzy(s)
+		normMap, _ := normalizeWithMap(s)
+		if norm != normMap {
+			t.Errorf("normalizeForFuzzy(%q) = %q, normalizeWithMap = %q", s, norm, normMap)
+		}
+	}
+}
+
+// ---------------------------------------------------------------------------
+// generateDiff — correct unified diff output
+// ---------------------------------------------------------------------------
+
+func TestGenerateDiff_SingleLineChange(t *testing.T) {
+	old := "line1\nline2\nline3\nline4\nline5\nline6\nline7\n"
+	new := "line1\nline2\nline3\nLINE4\nline5\nline6\nline7\n"
+
+	diff := generateDiff("test.go", old, new)
+
+	// Should contain standard unified diff markers
+	if !strings.Contains(diff, "--- test.go") {
+		t.Error("diff should contain --- header")
+	}
+	if !strings.Contains(diff, "+++ test.go") {
+		t.Error("diff should contain +++ header")
+	}
+	if !strings.Contains(diff, "@@") {
+		t.Error("diff should contain @@ hunk header")
+	}
+
+	// Should show the actual change
+	if !strings.Contains(diff, "-line4") {
+		t.Error("diff should show removed line")
+	}
+	if !strings.Contains(diff, "+LINE4") {
+		t.Error("diff should show added line")
+	}
+
+	// Should NOT mark all remaining lines as changed (the old bug)
+	deletedCount := strings.Count(diff, "\n-")
+	if deletedCount > 2 { // at most 1 deleted line + some tolerance
+		t.Errorf("diff shows %d deletions, expected ~1 (old bug: marked rest of file as deleted)", deletedCount)
+	}
+}
+
+func TestGenerateDiff_MultiLineChange(t *testing.T) {
+	old := "aaa\nbbb\nccc\nddd\n"
+	new := "aaa\nBBB\nCCC\nddd\n"
+
+	diff := generateDiff("x.go", old, new)
+	if !strings.Contains(diff, "-bbb") {
+		t.Error("diff should show bbb removed")
+	}
+	if !strings.Contains(diff, "-ccc") {
+		t.Error("diff should show ccc removed")
+	}
+	if !strings.Contains(diff, "+BBB") {
+		t.Error("diff should show BBB added")
+	}
+	if !strings.Contains(diff, "+CCC") {
+		t.Error("diff should show CCC added")
+	}
+}
+
+func TestGenerateDiff_NoChange(t *testing.T) {
+	content := "hello\nworld\n"
+	diff := generateDiff("x.go", content, content)
+	if diff != "" {
+		t.Errorf("expected empty diff for identical content, got %q", diff)
+	}
+}
+
+func TestGenerateDiff_Addition(t *testing.T) {
+	old := "line1\nline2\n"
+	new := "line1\nnew line\nline2\n"
+
+	diff := generateDiff("x.go", old, new)
+	if !strings.Contains(diff, "+new line") {
+		t.Error("diff should show added line")
+	}
+}
+
+func TestGenerateDiff_Deletion(t *testing.T) {
+	old := "line1\nremove me\nline2\n"
+	new := "line1\nline2\n"
+
+	diff := generateDiff("x.go", old, new)
+	if !strings.Contains(diff, "-remove me") {
+		t.Error("diff should show deleted line")
+	}
+}
+
+// ---------------------------------------------------------------------------
+// End-to-end: executeEdit via tool call
+// ---------------------------------------------------------------------------
+
+func TestExecuteEdit_ExactMatch(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.go")
+	original := "func main() {\n\tfmt.Println(\"hello\")\n}\n"
+	writeFileOrFail(t, path, original)
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "fmt.Println(\"hello\")",
+		NewText: "fmt.Println(\"world\")",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("tool returned error: %s", resp.Content)
+	}
+
+	got, _ := os.ReadFile(path)
+	want := "func main() {\n\tfmt.Println(\"world\")\n}\n"
+	if string(got) != want {
+		t.Errorf("file content=%q, want=%q", string(got), want)
+	}
+}
+
+func TestExecuteEdit_ExactMatch_DoesNotCorruptRest(t *testing.T) {
+	// This is the key regression test for the screenshot bug: editing a
+	// small section must NOT delete/corrupt the rest of the file.
+	dir := t.TempDir()
+	path := filepath.Join(dir, "big.go")
+
+	var lines []string
+	for i := 1; i <= 100; i++ {
+		lines = append(lines, fmt.Sprintf("line_%03d_%s", i, strings.Repeat("x", 40)))
+	}
+	original := strings.Join(lines, "\n") + "\n"
+	writeFileOrFail(t, path, original)
+
+	// Replace just line 50
+	target := lines[49]
+	replacement := "REPLACED_LINE_50"
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: target,
+		NewText: replacement,
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("tool returned error: %s", resp.Content)
+	}
+
+	got, _ := os.ReadFile(path)
+	gotLines := strings.Split(string(got), "\n")
+
+	// File should still have 101 elements (100 lines + trailing empty)
+	if len(gotLines) != 101 {
+		t.Fatalf("file has %d lines, want 101 (content was corrupted)", len(gotLines))
+	}
+
+	// Line 50 should be replaced
+	if gotLines[49] != replacement {
+		t.Errorf("line 50=%q, want=%q", gotLines[49], replacement)
+	}
+
+	// Lines before and after should be untouched
+	if gotLines[0] != lines[0] {
+		t.Errorf("line 1 corrupted: %q", gotLines[0])
+	}
+	if gotLines[98] != lines[98] {
+		t.Errorf("line 99 corrupted: %q", gotLines[98])
+	}
+}
+
+func TestExecuteEdit_FuzzyMatch_TrailingWhitespace(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "ws.go")
+	// File has trailing whitespace on some lines
+	original := "func foo() {   \n\treturn 1   \n}\nfunc bar() {\n}\n"
+	writeFileOrFail(t, path, original)
+
+	// Search without trailing whitespace (common LLM behavior)
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "func foo() {\n\treturn 1\n}",
+		NewText: "func foo() {\n\treturn 2\n}",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("tool returned error: %s", resp.Content)
+	}
+
+	got, _ := os.ReadFile(path)
+	gotStr := string(got)
+
+	// The fuzzy match replaces the matched region (which includes trailing
+	// whitespace) with the new_text. The key invariant is that the rest of
+	// the file (func bar) must be preserved.
+	if !strings.Contains(gotStr, "return 2") {
+		t.Error("edit was not applied: missing 'return 2'")
+	}
+	if !strings.Contains(gotStr, "func bar()") {
+		t.Errorf("file was corrupted: missing func bar(). got=%q", gotStr)
+	}
+
+	// Verify response mentions fuzzy match
+	if !strings.Contains(resp.Content, "fuzzy match") {
+		t.Error("response should mention fuzzy match")
+	}
+}
+
+func TestExecuteEdit_FuzzyMatch_DoesNotCorruptRest(t *testing.T) {
+	// Regression test: fuzzy match must not corrupt content after the match.
+	dir := t.TempDir()
+	path := filepath.Join(dir, "fuzzy.txt")
+
+	// 20 lines, each with trailing whitespace
+	var lines []string
+	for i := 1; i <= 20; i++ {
+		lines = append(lines, strings.Repeat("x", 10)+"   ") // trailing spaces
+	}
+	original := strings.Join(lines, "\n") + "\nEND\n"
+	writeFileOrFail(t, path, original)
+
+	// Search for lines 10-11 without trailing whitespace
+	search := strings.Repeat("x", 10) + "\n" + strings.Repeat("x", 10)
+	// But this matches lines 1-2, 2-3, etc. — should fail due to ambiguity.
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: search,
+		NewText: "REPLACED",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+
+	// This should either fail (ambiguous) or produce correct output.
+	// With identical lines, fuzzy match should refuse (ambiguous).
+	got, _ := os.ReadFile(path)
+	if !resp.IsError {
+		// If it didn't error, verify the file is not corrupted
+		if !strings.HasSuffix(string(got), "END\n") {
+			t.Error("file was corrupted: missing END marker")
+		}
+	}
+}
+
+func TestExecuteEdit_MultipleMatches_Fails(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "dup.txt")
+	writeFileOrFail(t, path, "hello\nworld\nhello\n")
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "hello",
+		NewText: "goodbye",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if !resp.IsError {
+		t.Error("expected error for multiple matches")
+	}
+	if !strings.Contains(resp.Content, "2 matches") {
+		t.Errorf("expected '2 matches' in error, got: %s", resp.Content)
+	}
+
+	// File should be untouched
+	got, _ := os.ReadFile(path)
+	if string(got) != "hello\nworld\nhello\n" {
+		t.Error("file was modified despite error")
+	}
+}
+
+func TestExecuteEdit_NoMatch_Fails(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "nomatch.txt")
+	writeFileOrFail(t, path, "hello world\n")
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "nonexistent text",
+		NewText: "replacement",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if !resp.IsError {
+		t.Error("expected error for no match")
+	}
+
+	// File should be untouched
+	got, _ := os.ReadFile(path)
+	if string(got) != "hello world\n" {
+		t.Error("file was modified despite error")
+	}
+}
+
+func TestExecuteEdit_CRLFNormalization(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "crlf.txt")
+	writeFileOrFail(t, path, "line1\r\nline2\r\nline3\r\n")
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "line2",
+		NewText: "LINE2",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("executeEdit error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("tool returned error: %s", resp.Content)
+	}
+
+	got, _ := os.ReadFile(path)
+	if !strings.Contains(string(got), "LINE2") {
+		t.Error("edit was not applied")
+	}
+}
+
+func TestExecuteEdit_MissingPath(t *testing.T) {
+	input, _ := json.Marshal(editArgs{
+		OldText: "x",
+		NewText: "y",
+	})
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !resp.IsError {
+		t.Error("expected error for missing path")
+	}
+}
+
+func TestExecuteEdit_NonexistentFile(t *testing.T) {
+	input, _ := json.Marshal(editArgs{
+		Path:    "/tmp/nonexistent_edit_test_file_12345.go",
+		OldText: "x",
+		NewText: "y",
+	})
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !resp.IsError {
+		t.Error("expected error for nonexistent file")
+	}
+}
+
+func TestExecuteEdit_DiffContainsHunkHeader(t *testing.T) {
+	// The UI's extractDiffStartLine parses @@ -N from the result.
+	// Verify the diff output contains it.
+	dir := t.TempDir()
+	path := filepath.Join(dir, "hunk.go")
+	var lines []string
+	for i := 1; i <= 20; i++ {
+		lines = append(lines, fmt.Sprintf("line_%02d_content", i))
+	}
+	writeFileOrFail(t, path, strings.Join(lines, "\n")+"\n")
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "line_10_content",
+		NewText: "REPLACED",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+	if resp.IsError {
+		t.Fatalf("tool error: %s", resp.Content)
+	}
+	if !strings.Contains(resp.Content, "@@ ") {
+		t.Error("diff output should contain @@ hunk header for UI parsing")
+	}
+}
+
+func TestExecuteEdit_MetadataContainsFileDiffs(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "meta.go")
+	writeFileOrFail(t, path, "old content\n")
+
+	input, _ := json.Marshal(editArgs{
+		Path:    path,
+		OldText: "old content",
+		NewText: "new content",
+	})
+
+	resp, err := executeEdit(t.Context(), fantasy.ToolCall{Input: string(input)}, dir)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	// Check metadata is present
+	metaJSON := resp.Metadata
+	if metaJSON == "" {
+		t.Fatal("expected metadata on response")
+	}
+
+	var meta map[string]any
+	if err := json.Unmarshal([]byte(metaJSON), &meta); err != nil {
+		t.Fatalf("metadata is not valid JSON: %v", err)
+	}
+
+	diffs, ok := meta["file_diffs"]
+	if !ok {
+		t.Fatal("metadata missing file_diffs key")
+	}
+
+	diffList, ok := diffs.([]any)
+	if !ok || len(diffList) == 0 {
+		t.Fatal("file_diffs should be a non-empty array")
+	}
+}

internal/core/subagent.go

@@ -28,7 +28,9 @@ type SubagentSpawnResult struct {
 // SubagentSpawnFunc is a callback that spawns an in-process subagent. The
 // parent Kit instance injects this into the context so the core tool can
 // call back without importing pkg/kit (which would create a cycle).
-type SubagentSpawnFunc func(ctx context.Context, prompt, model, systemPrompt string, timeout time.Duration) (*SubagentSpawnResult, error)
+// The toolCallID parameter is the LLM-assigned ID of the spawn_subagent
+// tool call, enabling the parent to correlate subagent events.
+type SubagentSpawnFunc func(ctx context.Context, toolCallID, prompt, model, systemPrompt string, timeout time.Duration) (*SubagentSpawnResult, error)
 
 type subagentCtxKey struct{}
 
@@ -128,8 +130,16 @@ func executeSubagent(ctx context.Context, call fantasy.ToolCall) (fantasy.ToolRe
 		), fmt.Errorf("no subagent spawner in context")
 	}
 
+	// Detach from the parent's deadline so the subagent gets its own
+	// independent timeout (applied downstream in Kit.Subagent). The parent
+	// context may carry a tight deadline from the LLM generation loop or
+	// other tool timeouts that would prematurely kill the subagent.
+	// We preserve context values (spawner, etc.) and propagate parent
+	// cancellation (e.g. user hits Ctrl-C) without inheriting the deadline.
+	spawnCtx := detachedWithCancel(ctx)
+
 	// Spawn in-process subagent.
-	result, err := spawner(ctx, args.Task, args.Model, args.SystemPrompt, timeout)
+	result, err := spawner(spawnCtx, call.ID, args.Task, args.Model, args.SystemPrompt, timeout)
 	if err != nil || result.Error != nil {
 		spawnErr := err
 		if spawnErr == nil {
@@ -162,6 +172,39 @@ func executeSubagent(ctx context.Context, call fantasy.ToolCall) (fantasy.ToolRe
 	return resp, nil
 }
 
+// ---------------------------------------------------------------------------
+// Context detachment
+// ---------------------------------------------------------------------------
+
+// detachedContext wraps a parent context, preserving its values but removing
+// its deadline and cancellation. This allows the subagent to have its own
+// independent timeout while still accessing context-stored values (e.g. the
+// subagent spawner function).
+type detachedContext struct {
+	parent context.Context
+}
+
+func (d detachedContext) Deadline() (time.Time, bool) { return time.Time{}, false }
+func (d detachedContext) Done() <-chan struct{}       { return nil }
+func (d detachedContext) Err() error                  { return nil }
+func (d detachedContext) Value(key any) any           { return d.parent.Value(key) }
+
+// detachedWithCancel creates a new context that inherits values from the
+// parent but has no deadline. Cancellation of the parent is propagated: when
+// the parent is cancelled the returned context is also cancelled, but the
+// parent's deadline does not apply to the child.
+func detachedWithCancel(parent context.Context) context.Context {
+	child, cancel := context.WithCancel(detachedContext{parent: parent})
+	go func() {
+		select {
+		case <-parent.Done():
+			cancel()
+		case <-child.Done():
+		}
+	}()
+	return child
+}
+
 // truncateResponse limits the response length to avoid overwhelming context windows.
 func truncateResponse(s string, maxLen int) string {
 	if len(s) <= maxLen {

internal/core/truncate.go

@@ -6,14 +6,17 @@ import (
 )
 
 const (
-	defaultMaxLines = 2000
-	defaultMaxBytes = 50 * 1024 // 50KB
-	grepMaxLineLen  = 500
+	defaultMaxLines   = 2000
+	defaultMaxBytes   = 50 * 1024 // 50KB
+	defaultMaxLineLen = 2000      // max characters per line before truncation
+	grepMaxLineLen    = 500
 
 	// DefaultMaxLines is the exported default line limit for truncation.
 	DefaultMaxLines = defaultMaxLines
 	// DefaultMaxBytes is the exported default byte limit for truncation.
 	DefaultMaxBytes = defaultMaxBytes
+	// DefaultMaxLineLen is the exported default per-line character limit.
+	DefaultMaxLineLen = defaultMaxLineLen
 )
 
 // TruncationResult describes how output was truncated.
@@ -26,6 +29,8 @@ type TruncationResult struct {
 }
 
 // TruncateTail keeps the last maxLines lines and at most maxBytes bytes.
+// Individual lines longer than defaultMaxLineLen are truncated to prevent
+// extremely long single lines from blowing up the TUI when wrapped.
 // Used for bash output where the tail is most relevant.
 func TruncateTail(content string, maxLines, maxBytes int) TruncationResult {
 	if maxLines <= 0 {
@@ -38,11 +43,11 @@ func TruncateTail(content string, maxLines, maxBytes int) TruncationResult {
 	lines := strings.Split(content, "\n")
 	total := len(lines)
 
-	if len(content) <= maxBytes && total <= maxLines {
-		return TruncationResult{Content: content, Total: total, Kept: total}
-	}
+	// Truncate individual long lines first to prevent single lines from
+	// wrapping into hundreds of visual lines in the TUI.
+	lines = truncateLongLines(lines, defaultMaxLineLen)
 
-	// Truncate by lines first (keep tail)
+	// Truncate by lines (keep tail)
 	truncBy := ""
 	if total > maxLines {
 		lines = lines[total-maxLines:]
@@ -78,6 +83,7 @@ func TruncateTail(content string, maxLines, maxBytes int) TruncationResult {
 }
 
 // truncateHead keeps the first maxLines lines and at most maxBytes bytes.
+// Individual lines longer than defaultMaxLineLen are truncated.
 // Used for read, grep, find, ls output where the head is most relevant.
 func truncateHead(content string, maxLines, maxBytes int) TruncationResult {
 	if maxLines <= 0 {
@@ -90,9 +96,8 @@ func truncateHead(content string, maxLines, maxBytes int) TruncationResult {
 	lines := strings.Split(content, "\n")
 	total := len(lines)
 
-	if len(content) <= maxBytes && total <= maxLines {
-		return TruncationResult{Content: content, Total: total, Kept: total}
-	}
+	// Truncate individual long lines first.
+	lines = truncateLongLines(lines, defaultMaxLineLen)
 
 	truncBy := ""
 	if total > maxLines {
@@ -125,6 +130,19 @@ func truncateHead(content string, maxLines, maxBytes int) TruncationResult {
 	}
 }
 
+// truncateLongLines caps each line to maxLen characters, appending a
+// "[...N chars truncated]" marker to any line that exceeds the limit.
+// This prevents a single very long line (e.g. minified JSON/JS) from
+// wrapping into hundreds of visual rows and blowing up the TUI.
+func truncateLongLines(lines []string, maxLen int) []string {
+	for i, line := range lines {
+		if len(line) > maxLen {
+			lines[i] = line[:maxLen] + fmt.Sprintf("... [%d chars truncated]", len(line)-maxLen)
+		}
+	}
+	return lines
+}
+
 // truncateLine truncates a single line to maxChars, appending "..." if cut.
 func truncateLine(line string, maxChars int) string {
 	if maxChars <= 0 {

internal/core/truncate_test.go

@@ -0,0 +1,163 @@
+package core
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestTruncateTail_LongLines(t *testing.T) {
+	// A single line of 5000 chars should be truncated to defaultMaxLineLen.
+	longLine := strings.Repeat("x", 5000)
+	tr := TruncateTail(longLine, 2000, 50*1024)
+
+	if len(tr.Content) > defaultMaxLineLen+100 { // +100 for the "[...N chars truncated]" suffix
+		t.Errorf("single long line not truncated: got %d chars, want <= %d", len(tr.Content), defaultMaxLineLen+100)
+	}
+	if !strings.Contains(tr.Content, "chars truncated]") {
+		t.Error("truncated line should contain truncation marker")
+	}
+}
+
+func TestTruncateTail_NormalLines(t *testing.T) {
+	// Lines within the limit should pass through unchanged.
+	content := "line1\nline2\nline3"
+	tr := TruncateTail(content, 2000, 50*1024)
+	if tr.Content != content {
+		t.Errorf("got %q, want %q", tr.Content, content)
+	}
+	if tr.Truncated {
+		t.Error("should not be marked as truncated")
+	}
+}
+
+func TestTruncateTail_LineCount(t *testing.T) {
+	lines := make([]string, 100)
+	for i := range lines {
+		lines[i] = "line"
+	}
+	content := strings.Join(lines, "\n")
+	tr := TruncateTail(content, 10, 50*1024)
+
+	if !tr.Truncated {
+		t.Error("should be marked as truncated")
+	}
+	if tr.Total != 100 {
+		t.Errorf("total = %d, want 100", tr.Total)
+	}
+	if tr.Kept != 10 {
+		t.Errorf("kept = %d, want 10", tr.Kept)
+	}
+}
+
+func TestTruncateHead_LongLines(t *testing.T) {
+	longLine := strings.Repeat("y", 5000)
+	tr := truncateHead(longLine, 2000, 50*1024)
+
+	if len(tr.Content) > defaultMaxLineLen+100 {
+		t.Errorf("single long line not truncated: got %d chars, want <= %d", len(tr.Content), defaultMaxLineLen+100)
+	}
+	if !strings.Contains(tr.Content, "chars truncated]") {
+		t.Error("truncated line should contain truncation marker")
+	}
+}
+
+func TestTruncateHead_NormalLines(t *testing.T) {
+	content := "line1\nline2\nline3"
+	tr := truncateHead(content, 2000, 50*1024)
+	if tr.Content != content {
+		t.Errorf("got %q, want %q", tr.Content, content)
+	}
+	if tr.Truncated {
+		t.Error("should not be marked as truncated")
+	}
+}
+
+func TestTruncateHead_LineCount(t *testing.T) {
+	lines := make([]string, 100)
+	for i := range lines {
+		lines[i] = "line"
+	}
+	content := strings.Join(lines, "\n")
+	tr := truncateHead(content, 10, 50*1024)
+
+	if !tr.Truncated {
+		t.Error("should be marked as truncated")
+	}
+	if tr.Total != 100 {
+		t.Errorf("total = %d, want 100", tr.Total)
+	}
+	if tr.Kept != 10 {
+		t.Errorf("kept = %d, want 10", tr.Kept)
+	}
+}
+
+func TestTruncateLongLines(t *testing.T) {
+	lines := []string{
+		"short",
+		strings.Repeat("a", 3000),
+		"also short",
+	}
+	result := truncateLongLines(lines, 100)
+
+	if result[0] != "short" {
+		t.Error("short line should be unchanged")
+	}
+	if len(result[1]) > 200 { // 100 chars + marker
+		t.Errorf("long line not truncated: len=%d", len(result[1]))
+	}
+	if !strings.Contains(result[1], "chars truncated]") {
+		t.Error("should contain truncation marker")
+	}
+	if result[2] != "also short" {
+		t.Error("short line should be unchanged")
+	}
+}
+
+func TestTruncateTail_MixedLongAndManyLines(t *testing.T) {
+	// 50 lines, each 3000 chars — tests both per-line and total truncation.
+	lines := make([]string, 50)
+	for i := range lines {
+		lines[i] = strings.Repeat("z", 3000)
+	}
+	content := strings.Join(lines, "\n")
+
+	tr := TruncateTail(content, 10, 50*1024)
+
+	// Should keep 10 lines.
+	if tr.Kept != 10 {
+		t.Errorf("kept = %d, want 10", tr.Kept)
+	}
+	// Each line should be capped at ~defaultMaxLineLen.
+	resultLines := strings.Split(tr.Content, "\n")
+	for i, line := range resultLines {
+		if len(line) > defaultMaxLineLen+100 {
+			t.Errorf("line %d too long: %d chars", i, len(line))
+		}
+	}
+}
+
+func TestTruncateLine(t *testing.T) {
+	short := "hello"
+	if truncateLine(short, 10) != short {
+		t.Error("short line should be unchanged")
+	}
+
+	long := strings.Repeat("x", 100)
+	result := truncateLine(long, 10)
+	if len(result) != 13 { // 10 + "..."
+		t.Errorf("got len %d, want 13", len(result))
+	}
+
+	// Default max for 0 — input shorter than default, so unchanged
+	result2 := truncateLine(long, 0)
+	if result2 != long {
+		t.Errorf("100-char line should be unchanged when maxChars defaults to %d", grepMaxLineLen)
+	}
+
+	// Longer input with default
+	veryLong := strings.Repeat("x", 1000)
+	result3 := truncateLine(veryLong, 0)
+	if len(result3) != grepMaxLineLen+3 {
+		t.Errorf("got len %d, want %d", len(result3), grepMaxLineLen+3)
+	}
+}

internal/extensions/api.go

@@ -727,6 +727,7 @@ type API struct {
 	onToolCall                func(func(ToolCallEvent, Context) *ToolCallResult)
 	onToolExecStart           func(func(ToolExecutionStartEvent, Context))
 	onToolExecEnd             func(func(ToolExecutionEndEvent, Context))
+	onToolOutput              func(func(ToolOutputEvent, Context))
 	onToolResult              func(func(ToolResultEvent, Context) *ToolResultResult)
 	onInput                   func(func(InputEvent, Context) *InputResult)
 	onBeforeAgentStart        func(func(BeforeAgentStartEvent, Context) *BeforeAgentStartResult)
@@ -749,6 +750,9 @@ type API struct {
 	registerOption            func(OptionDef)
 	registerShortcutFn        func(ShortcutDef, func(Context))
 	registerMessageRendererFn func(MessageRendererConfig)
+	onSubagentStart           func(func(SubagentStartEvent, Context))
+	onSubagentChunk           func(func(SubagentChunkEvent, Context))
+	onSubagentEnd             func(func(SubagentEndEvent, Context))
 }
 
 // OnToolCall registers a handler that fires before a tool executes.
@@ -767,12 +771,40 @@ func (a *API) OnToolExecutionEnd(handler func(ToolExecutionEndEvent, Context)) {
 	a.onToolExecEnd(handler)
 }
 
+// OnToolOutput registers a handler for streaming tool output chunks.
+// This fires for each output line as it arrives from tools like bash,
+// allowing extensions to observe or process output in real-time.
+func (a *API) OnToolOutput(handler func(ToolOutputEvent, Context)) {
+	a.onToolOutput(handler)
+}
+
 // OnToolResult registers a handler that fires after tool execution.
 // Return a non-nil ToolResultResult to modify the output.
 func (a *API) OnToolResult(handler func(ToolResultEvent, Context) *ToolResultResult) {
 	a.onToolResult(handler)
 }
 
+// OnSubagentStart registers a handler that fires when a spawn_subagent tool
+// call begins executing. Use the ToolCallID to correlate with subsequent
+// OnSubagentChunk and OnSubagentEnd events for the same subagent.
+func (a *API) OnSubagentStart(handler func(SubagentStartEvent, Context)) {
+	a.onSubagentStart(handler)
+}
+
+// OnSubagentChunk registers a handler for real-time events from a running
+// subagent. ChunkType identifies the kind of event ("text", "tool_call",
+// "tool_result", "tool_execution_start", "tool_execution_end", etc.).
+// Correlate with OnSubagentStart via the ToolCallID field.
+func (a *API) OnSubagentChunk(handler func(SubagentChunkEvent, Context)) {
+	a.onSubagentChunk(handler)
+}
+
+// OnSubagentEnd registers a handler that fires when a spawn_subagent call
+// completes. ErrorMsg is non-empty when the subagent failed.
+func (a *API) OnSubagentEnd(handler func(SubagentEndEvent, Context)) {
+	a.onSubagentEnd(handler)
+}
+
 // OnInput registers a handler that fires when user input is received.
 // Return a non-nil InputResult to transform or handle the input.
 func (a *API) OnInput(handler func(InputEvent, Context) *InputResult) {
@@ -1538,6 +1570,19 @@ type ToolExecutionEndEvent struct {
 
 func (e ToolExecutionEndEvent) Type() EventType { return ToolExecutionEnd }
 
+// ToolOutputEvent fires when a tool produces streaming output chunks.
+// This is primarily used for long-running tools like bash to show output
+// in real-time as it arrives, before the tool completes.
+type ToolOutputEvent struct {
+	ToolCallID string
+	ToolName   string
+	ToolKind   string
+	Chunk      string // Output text chunk
+	IsStderr   bool   // Whether this chunk came from stderr
+}
+
+func (e ToolOutputEvent) Type() EventType { return ToolOutput }
+
 // ToolResultEvent fires after tool execution with the output.
 type ToolResultEvent struct {
 	ToolCallID string
@@ -1743,21 +1788,82 @@ type BeforeCompactEvent struct {
 func (e BeforeCompactEvent) Type() EventType { return BeforeCompact }
 
 // BeforeCompactResult controls whether compaction proceeds. Return
-// Cancel=true with an optional Reason to block compaction.
+// Cancel=true with an optional Reason to block compaction, or provide
+// a custom Summary to replace the default LLM-generated one.
 type BeforeCompactResult struct {
 	// Cancel, when true, prevents compaction from proceeding.
 	Cancel bool
 	// Reason is a human-readable explanation shown to the user when
 	// Cancel is true. Empty string uses a default message.
 	Reason string
+	// Summary, when non-empty, replaces the default LLM-generated summary.
+	// The extension is responsible for generating a useful summary.
+	// Ignored when Cancel is true.
+	Summary string
 }
 
 func (BeforeCompactResult) isResult() {}
 
 // ---------------------------------------------------------------------------
-// Theme types (exposed to Yaegi — concrete structs, string hex colors)
+// Subagent lifecycle events (exposed to Yaegi — concrete structs)
 // ---------------------------------------------------------------------------
 
+// SubagentStartEvent fires when a spawn_subagent tool call begins executing.
+type SubagentStartEvent struct {
+	// ToolCallID is the LLM-assigned ID of the spawn_subagent tool call.
+	// Use this to correlate SubagentChunkEvent and SubagentEndEvent.
+	ToolCallID string
+	// Task is the task description passed to the subagent.
+	Task string
+}
+
+func (e SubagentStartEvent) Type() EventType { return SubagentStart }
+
+// SubagentChunkEvent fires for each real-time event from a running subagent.
+// Type field indicates the kind of event; read the relevant fields accordingly.
+type SubagentChunkEvent struct {
+	// ToolCallID matches the SubagentStartEvent.ToolCallID for this subagent.
+	ToolCallID string
+	// Task is the task description (repeated for convenience).
+	Task string
+	// ChunkType identifies the event kind:
+	//   "text"                 — LLM text chunk (read Content)
+	//   "reasoning"            — reasoning/thinking delta (read Content)
+	//   "tool_call"            — subagent called a tool (read ToolName, ToolArgs)
+	//   "tool_result"          — tool returned a result (read ToolName, ToolResult, IsError)
+	//   "tool_execution_start" — tool began executing (read ToolName)
+	//   "tool_execution_end"   — tool finished executing (read ToolName)
+	//   "turn_start"           — subagent turn began
+	//   "turn_end"             — subagent turn ended
+	ChunkType string
+	// Content carries text for "text" and "reasoning" chunk types.
+	Content string
+	// ToolName is set on tool-related chunk types.
+	ToolName string
+	// ToolArgs is the JSON-encoded tool arguments for "tool_call" chunks.
+	ToolArgs string
+	// ToolResult is the tool output for "tool_result" chunks.
+	ToolResult string
+	// IsError is true when a "tool_result" chunk represents an error.
+	IsError bool
+}
+
+func (e SubagentChunkEvent) Type() EventType { return SubagentChunk }
+
+// SubagentEndEvent fires when a spawn_subagent tool call completes.
+type SubagentEndEvent struct {
+	// ToolCallID matches the SubagentStartEvent.ToolCallID for this subagent.
+	ToolCallID string
+	// Task is the task description.
+	Task string
+	// Response is the subagent's final text response (empty on error).
+	Response string
+	// ErrorMsg is non-empty when the subagent failed.
+	ErrorMsg string
+}
+
+func (e SubagentEndEvent) Type() EventType { return SubagentEnd }
+
 // ThemeColor is an adaptive color pair with light and dark hex values.
 // Either field may be empty to inherit from the default theme.
 type ThemeColor struct {

internal/extensions/events.go

@@ -19,6 +19,9 @@ const (
 	// ToolExecutionEnd fires when a tool finishes executing.
 	ToolExecutionEnd EventType = "tool_execution_end"
 
+	// ToolOutput fires when a tool produces streaming output chunks.
+	ToolOutput EventType = "tool_output"
+
 	// ToolResult fires after a tool executes. Handlers can modify the result.
 	ToolResult EventType = "tool_result"
 
@@ -68,6 +71,18 @@ const (
 	// BeforeCompact fires before context compaction runs. Handlers can
 	// cancel compaction by returning Cancel=true.
 	BeforeCompact EventType = "before_compact"
+
+	// SubagentStart fires when a spawn_subagent tool call begins executing.
+	// Carries the tool call ID and the task description.
+	SubagentStart EventType = "subagent_start"
+
+	// SubagentChunk fires for each real-time event emitted by a running
+	// subagent: text chunks, tool calls, tool results, etc.
+	SubagentChunk EventType = "subagent_chunk"
+
+	// SubagentEnd fires when a spawn_subagent tool call completes (success
+	// or error). Carries the final response and any error message.
+	SubagentEnd EventType = "subagent_end"
 )
 
 // AllEventTypes returns every supported event type.
@@ -79,6 +94,7 @@ func AllEventTypes() []EventType {
 		SessionStart, SessionShutdown,
 		ModelChange, ContextPrepare,
 		BeforeFork, BeforeSessionSwitch, BeforeCompact,
+		SubagentStart, SubagentChunk, SubagentEnd,
 	}
 }
 

internal/extensions/events_test.go

@@ -4,8 +4,8 @@ import "testing"
 
 func TestAllEventTypes_Count(t *testing.T) {
 	all := AllEventTypes()
-	if len(all) != 18 {
-		t.Fatalf("expected 18 event types, got %d", len(all))
+	if len(all) != 21 {
+		t.Fatalf("expected 21 event types, got %d", len(all))
 	}
 }
 
@@ -55,6 +55,9 @@ func TestEventType_TypeMethod(t *testing.T) {
 		{BeforeForkEvent{TargetID: "abc"}, BeforeFork},
 		{BeforeSessionSwitchEvent{Reason: "new"}, BeforeSessionSwitch},
 		{BeforeCompactEvent{EstimatedTokens: 1000}, BeforeCompact},
+		{SubagentStartEvent{ToolCallID: "x", Task: "t"}, SubagentStart},
+		{SubagentChunkEvent{ToolCallID: "x", ChunkType: "text"}, SubagentChunk},
+		{SubagentEndEvent{ToolCallID: "x"}, SubagentEnd},
 	}
 
 	for _, tt := range tests {

internal/extensions/loader.go

@@ -439,6 +439,12 @@ func loadSingleExtension(path string) (*LoadedExtension, error) {
 				return nil
 			})
 		},
+		onToolOutput: func(h func(ToolOutputEvent, Context)) {
+			reg(ToolOutput, func(e Event, c Context) Result {
+				h(e.(ToolOutputEvent), c)
+				return nil
+			})
+		},
 		onToolResult: func(h func(ToolResultEvent, Context) *ToolResultResult) {
 			reg(ToolResult, func(e Event, c Context) Result {
 				r := h(e.(ToolResultEvent), c)
@@ -574,6 +580,24 @@ func loadSingleExtension(path string) (*LoadedExtension, error) {
 		registerShortcutFn: func(def ShortcutDef, handler func(Context)) {
 			ext.Shortcuts = append(ext.Shortcuts, ShortcutEntry{Def: def, Handler: handler})
 		},
+		onSubagentStart: func(h func(SubagentStartEvent, Context)) {
+			reg(SubagentStart, func(e Event, c Context) Result {
+				h(e.(SubagentStartEvent), c)
+				return nil
+			})
+		},
+		onSubagentChunk: func(h func(SubagentChunkEvent, Context)) {
+			reg(SubagentChunk, func(e Event, c Context) Result {
+				h(e.(SubagentChunkEvent), c)
+				return nil
+			})
+		},
+		onSubagentEnd: func(h func(SubagentEndEvent, Context)) {
+			reg(SubagentEnd, func(e Event, c Context) Result {
+				h(e.(SubagentEndEvent), c)
+				return nil
+			})
+		},
 	}
 
 	// Call Init — the extension registers its handlers, tools, commands.

internal/extensions/symbols.go

@@ -119,6 +119,11 @@ func Symbols() interp.Exports {
 			"SubagentHandle": reflect.ValueOf((*SubagentHandle)(nil)),
 			"SubagentEvent":  reflect.ValueOf((*SubagentEvent)(nil)),
 
+			// Subagent lifecycle events
+			"SubagentStartEvent": reflect.ValueOf((*SubagentStartEvent)(nil)),
+			"SubagentChunkEvent": reflect.ValueOf((*SubagentChunkEvent)(nil)),
+			"SubagentEndEvent":   reflect.ValueOf((*SubagentEndEvent)(nil)),
+
 			// Theme types
 			"ThemeColor":       reflect.ValueOf((*ThemeColor)(nil)),
 			"ThemeColorConfig": reflect.ValueOf((*ThemeColorConfig)(nil)),
@@ -128,6 +133,7 @@ func Symbols() interp.Exports {
 			"ToolCallResult":          reflect.ValueOf((*ToolCallResult)(nil)),
 			"ToolExecutionStartEvent": reflect.ValueOf((*ToolExecutionStartEvent)(nil)),
 			"ToolExecutionEndEvent":   reflect.ValueOf((*ToolExecutionEndEvent)(nil)),
+			"ToolOutputEvent":         reflect.ValueOf((*ToolOutputEvent)(nil)),
 			"ToolResultEvent":         reflect.ValueOf((*ToolResultEvent)(nil)),
 			"ToolResultResult":        reflect.ValueOf((*ToolResultResult)(nil)),
 			"InputEvent":              reflect.ValueOf((*InputEvent)(nil)),

internal/extensions/test_api.go

@@ -30,6 +30,12 @@ func NewTestAPI(ext *LoadedExtension) API {
 				return nil
 			})
 		},
+		onToolOutput: func(h func(ToolOutputEvent, Context)) {
+			reg(ToolOutput, func(e Event, c Context) Result {
+				h(e.(ToolOutputEvent), c)
+				return nil
+			})
+		},
 		onToolResult: func(h func(ToolResultEvent, Context) *ToolResultResult) {
 			reg(ToolResult, func(e Event, c Context) Result {
 				r := h(e.(ToolResultEvent), c)
@@ -165,5 +171,23 @@ func NewTestAPI(ext *LoadedExtension) API {
 		registerMessageRendererFn: func(config MessageRendererConfig) {
 			ext.MessageRenderers = append(ext.MessageRenderers, config)
 		},
+		onSubagentStart: func(h func(SubagentStartEvent, Context)) {
+			reg(SubagentStart, func(e Event, c Context) Result {
+				h(e.(SubagentStartEvent), c)
+				return nil
+			})
+		},
+		onSubagentChunk: func(h func(SubagentChunkEvent, Context)) {
+			reg(SubagentChunk, func(e Event, c Context) Result {
+				h(e.(SubagentChunkEvent), c)
+				return nil
+			})
+		},
+		onSubagentEnd: func(h func(SubagentEndEvent, Context)) {
+			reg(SubagentEnd, func(e Event, c Context) Result {
+				h(e.(SubagentEndEvent), c)
+				return nil
+			})
+		},
 	}
 }

internal/message/content.go

@@ -4,11 +4,38 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"strings"
 	"time"
 
 	"charm.land/fantasy"
 )
 
+// sanitizeToolCallID ensures the ID matches Anthropic's required pattern:
+// ^[a-zA-Z0-9_-]+$ (alphanumeric, underscores, and hyphens only).
+// Invalid characters are replaced with underscores.
+func sanitizeToolCallID(id string) string {
+	var sb strings.Builder
+	for _, r := range id {
+		switch {
+		case (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z'):
+			sb.WriteRune(r)
+		case r >= '0' && r <= '9':
+			sb.WriteRune(r)
+		case r == '_' || r == '-':
+			sb.WriteRune(r)
+		default:
+			// Replace invalid characters with underscore
+			sb.WriteByte('_')
+		}
+	}
+	result := sb.String()
+	// Ensure non-empty (Anthropic requires at least one character)
+	if result == "" {
+		return "tool_0"
+	}
+	return result
+}
+
 // ContentPart is the marker interface for all message content block types.
 // A message contains a heterogeneous slice of ContentPart values, enabling
 // rich structured messages that carry text, reasoning, tool calls, tool
@@ -312,7 +339,7 @@ func (m *Message) ToFantasyMessages() []fantasy.Message {
 		// Add tool calls
 		for _, tc := range m.ToolCalls() {
 			parts = append(parts, fantasy.ToolCallPart{
-				ToolCallID: tc.ID,
+				ToolCallID: sanitizeToolCallID(tc.ID),
 				ToolName:   tc.Name,
 				Input:      tc.Input,
 			})
@@ -340,7 +367,7 @@ func (m *Message) ToFantasyMessages() []fantasy.Message {
 				}
 			}
 			parts = append(parts, fantasy.ToolResultPart{
-				ToolCallID: result.ToolCallID,
+				ToolCallID: sanitizeToolCallID(result.ToolCallID),
 				Output:     output,
 			})
 		}

internal/message/content_test.go

@@ -0,0 +1,113 @@
+package message
+
+import (
+	"testing"
+)
+
+func TestSanitizeToolCallID(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "valid alphanumeric ID",
+			input:    "call_123abc",
+			expected: "call_123abc",
+		},
+		{
+			name:     "ID with dots (OpenCode/Kimi style)",
+			input:    "call.123.abc",
+			expected: "call_123_abc",
+		},
+		{
+			name:     "ID with colons",
+			input:    "tool:123:abc",
+			expected: "tool_123_abc",
+		},
+		{
+			name:     "ID with special characters",
+			input:    "tool@#$%^&*()",
+			expected: "tool_________",
+		},
+		{
+			name:     "Anthropic style ID (already valid)",
+			input:    "toolu_0123456789ABCDEF",
+			expected: "toolu_0123456789ABCDEF",
+		},
+		{
+			name:     "OpenAI style ID (already valid)",
+			input:    "call_O17Uplv4lJvD6DVdIvFFeRMw",
+			expected: "call_O17Uplv4lJvD6DVdIvFFeRMw",
+		},
+		{
+			name:     "ID with hyphens",
+			input:    "my-tool-call-123",
+			expected: "my-tool-call-123",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "tool_0",
+		},
+		{
+			name:     "only special characters",
+			input:    "@#$%",
+			expected: "____",
+		},
+		{
+			name:     "mixed valid and invalid",
+			input:    "call_123.abc-def@ghi",
+			expected: "call_123_abc-def_ghi",
+		},
+		{
+			name:     "Unicode characters",
+			input:    "tool_日本語",
+			expected: "tool____",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := sanitizeToolCallID(tt.input)
+			if result != tt.expected {
+				t.Errorf("sanitizeToolCallID(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestSanitizeToolCallID_MatchesAnthropicPattern(t *testing.T) {
+	// Test that sanitized IDs match Anthropic's required pattern: ^[a-zA-Z0-9_-]+$
+	// This is a simplified check - in reality the pattern allows alphanumeric, underscore, hyphen
+	testIDs := []string{
+		"call.123.abc",
+		"tool:123:def",
+		"id@#$%^&*()",
+		"mixed.valid-id_test",
+		"",
+	}
+
+	for _, id := range testIDs {
+		sanitized := sanitizeToolCallID(id)
+
+		// Verify each character is valid
+		for i, r := range sanitized {
+			valid := (r >= 'a' && r <= 'z') ||
+				(r >= 'A' && r <= 'Z') ||
+				(r >= '0' && r <= '9') ||
+				r == '_' ||
+				r == '-'
+
+			if !valid {
+				t.Errorf("sanitizeToolCallID(%q) = %q, contains invalid character at position %d: %q",
+					id, sanitized, i, string(r))
+			}
+		}
+
+		// Verify non-empty
+		if sanitized == "" {
+			t.Errorf("sanitizeToolCallID(%q) returned empty string", id)
+		}
+	}
+}

internal/models/custom.go

@@ -0,0 +1,74 @@
+package models
+
+import (
+	"log"
+
+	"github.com/spf13/viper"
+)
+
+// loadCustomModelsFromConfig loads custom model definitions from the config file
+// and returns them as a map of model ID -> ModelInfo. Returns nil if no custom
+// models are configured.
+func loadCustomModelsFromConfig() map[string]ModelInfo {
+	if !viper.IsSet("customModels") {
+		return nil
+	}
+
+	var customModels map[string]CustomModelConfig
+	if err := viper.UnmarshalKey("customModels", &customModels); err != nil {
+		log.Printf("Warning: Failed to parse customModels: %v", err)
+		return nil
+	}
+
+	result := make(map[string]ModelInfo, len(customModels))
+	for modelID, cfg := range customModels {
+		info := modelConfigToModelInfo(modelID, cfg)
+		result[modelID] = info
+	}
+
+	return result
+}
+
+// modelConfigToModelInfo converts a CustomModelConfig to a ModelInfo.
+func modelConfigToModelInfo(modelID string, cfg CustomModelConfig) ModelInfo {
+	return ModelInfo{
+		ID:          modelID,
+		Name:        cfg.Name,
+		Attachment:  cfg.Attachment,
+		Reasoning:   cfg.Reasoning,
+		Temperature: cfg.Temperature,
+		Cost: Cost{
+			Input:  cfg.Cost.Input,
+			Output: cfg.Cost.Output,
+		},
+		Limit: Limit{
+			Context: cfg.Limit.Context,
+			Output:  cfg.Limit.Output,
+		},
+	}
+}
+
+// CustomModelConfig defines a custom model configuration loaded from the config file.
+// This is a duplicate here to avoid circular dependencies with internal/config.
+type CustomModelConfig struct {
+	Name        string      `json:"name" yaml:"name"`
+	Family      string      `json:"family,omitempty" yaml:"family,omitempty"`
+	Attachment  bool        `json:"attachment,omitempty" yaml:"attachment,omitempty"`
+	Reasoning   bool        `json:"reasoning,omitempty" yaml:"reasoning,omitempty"`
+	Temperature bool        `json:"temperature,omitempty" yaml:"temperature,omitempty"`
+	Knowledge   string      `json:"knowledge,omitempty" yaml:"knowledge,omitempty"`
+	Cost        CostConfig  `json:"cost" yaml:"cost"`
+	Limit       LimitConfig `json:"limit" yaml:"limit"`
+}
+
+// CostConfig defines the pricing for a custom model.
+type CostConfig struct {
+	Input  float64 `json:"input" yaml:"input"`
+	Output float64 `json:"output" yaml:"output"`
+}
+
+// LimitConfig defines context and output limits for a custom model.
+type LimitConfig struct {
+	Context int `json:"context" yaml:"context"`
+	Output  int `json:"output" yaml:"output"`
+}

internal/models/modelsdb.go

@@ -17,15 +17,21 @@ type modelsDBProvider struct {
 
 // modelsDBModel represents a model entry from models.dev/api.json.
 type modelsDBModel struct {
-	ID          string        `json:"id"`
-	Name        string        `json:"name"`
-	Family      string        `json:"family,omitempty"`
-	Attachment  bool          `json:"attachment"`
-	Reasoning   bool          `json:"reasoning"`
-	ToolCall    bool          `json:"tool_call"`
-	Temperature bool          `json:"temperature"`
-	Cost        modelsDBCost  `json:"cost"`
-	Limit       modelsDBLimit `json:"limit"`
+	ID          string                 `json:"id"`
+	Name        string                 `json:"name"`
+	Family      string                 `json:"family,omitempty"`
+	Attachment  bool                   `json:"attachment"`
+	Reasoning   bool                   `json:"reasoning"`
+	ToolCall    bool                   `json:"tool_call"`
+	Temperature bool                   `json:"temperature"`
+	Cost        modelsDBCost           `json:"cost"`
+	Limit       modelsDBLimit          `json:"limit"`
+	Provider    *modelsDBModelProvider `json:"provider,omitempty"` // Model-specific provider override
+}
+
+// modelsDBModelProvider represents a provider reference within a model.
+type modelsDBModelProvider struct {
+	NPM string `json:"npm"`
 }
 
 // modelsDBCost represents model pricing from models.dev.

internal/models/providers.go

@@ -169,6 +169,9 @@ type ProviderResult struct {
 	// ProviderOptions contains provider-specific options to be passed to the
 	// fantasy agent (e.g. OpenAI Responses API reasoning options).
 	ProviderOptions fantasy.ProviderOptions
+	// SkipMaxOutputTokens indicates that this provider doesn't support the
+	// max_output_tokens parameter (e.g., OpenAI Codex OAuth API).
+	SkipMaxOutputTokens bool
 }
 
 // ParseModelString parses a model string in "provider/model" format (e.g. "anthropic/claude-sonnet-4-5").
@@ -253,6 +256,8 @@ func CreateProvider(ctx context.Context, config *ProviderConfig) (*ProviderResul
 		return createBedrockProvider(ctx, config, modelName)
 	case "vercel":
 		return createVercelProvider(ctx, config, modelName)
+	case "custom":
+		return createCustomProvider(ctx, config, modelName)
 	default:
 		return autoRouteProvider(ctx, config, provider, modelName, registry)
 	}
@@ -261,14 +266,22 @@ func CreateProvider(ctx context.Context, config *ProviderConfig) (*ProviderResul
 // autoRouteProvider attempts to create a provider by looking up its npm package
 // in the models.dev database and routing through the appropriate fantasy provider.
 // For openai-compatible providers, it uses the api URL from models.dev.
+// Models may have a provider override that specifies a different npm package than
+// the provider's default (e.g., opencode's claude-opus-4-6 uses @ai-sdk/anthropic).
 func autoRouteProvider(ctx context.Context, config *ProviderConfig, provider, modelName string, registry *ModelsRegistry) (*ProviderResult, error) {
 	providerInfo := registry.GetProviderInfo(provider)
 	if providerInfo == nil {
 		return nil, fmt.Errorf("unsupported provider: %s (not found in model database)", provider)
 	}
 
+	// Check for model-specific provider override
+	npmPackage := providerInfo.NPM
+	if modelInfo := registry.LookupModel(provider, modelName); modelInfo != nil && modelInfo.ProviderNPM != "" {
+		npmPackage = modelInfo.ProviderNPM
+	}
+
 	// Determine the fantasy provider for this npm package
-	fantasyProvider := npmToFantasyProvider[providerInfo.NPM]
+	fantasyProvider := npmToFantasyProvider[npmPackage]
 	if fantasyProvider == "" && providerInfo.API != "" {
 		// Unknown npm but has API URL → route through openaicompat
 		fantasyProvider = "openaicompat"
@@ -288,7 +301,7 @@ func autoRouteProvider(ctx context.Context, config *ProviderConfig, provider, mo
 		}
 		return createAutoRoutedOpenAIProvider(ctx, config, modelName, providerInfo)
 	default:
-		return nil, fmt.Errorf("unsupported provider: %s (npm: %s has no fantasy mapping)", provider, providerInfo.NPM)
+		return nil, fmt.Errorf("unsupported provider: %s (npm: %s has no fantasy mapping)", provider, npmPackage)
 	}
 }
 
@@ -346,7 +359,10 @@ func createAutoRoutedAnthropicProvider(ctx context.Context, config *ProviderConf
 	opts = append(opts, anthropic.WithAPIKey(apiKey))
 
 	if config.ProviderURL != "" {
-		opts = append(opts, anthropic.WithBaseURL(config.ProviderURL))
+		// The anthropic client appends "/v1/messages" to the base URL.
+		// If the provider URL ends with "/v1", strip it to avoid double "/v1/v1" paths.
+		baseURL := strings.TrimSuffix(config.ProviderURL, "/v1")
+		opts = append(opts, anthropic.WithBaseURL(baseURL))
 	}
 
 	if config.TLSSkipVerify {
@@ -608,13 +624,52 @@ func createVertexAnthropicProvider(ctx context.Context, config *ProviderConfig,
 
 func createOpenAIProvider(ctx context.Context, config *ProviderConfig, modelName string) (*ProviderResult, error) {
 	apiKey := config.ProviderAPIKey
+	source := "command-line flag"
+	var accountID string
+	var isCodexOAuth bool
+
 	if apiKey == "" {
-		apiKey = os.Getenv("OPENAI_API_KEY")
-	}
-	if apiKey == "" {
-		return nil, fmt.Errorf("OpenAI API key not provided. Use --provider-api-key flag or OPENAI_API_KEY environment variable")
+		// Check stored credentials first
+		cm, err := auth.NewCredentialManager()
+		if err == nil {
+			if creds, err := cm.GetOpenAICredentials(); err == nil && creds != nil {
+				if creds.Type == "oauth" && creds.AccessToken != "" {
+					// For OAuth, get a valid access token (may refresh if needed)
+					token, err := cm.GetValidOpenAIAccessToken()
+					if err == nil && token != "" {
+						apiKey = token
+						accountID = creds.AccountID
+						isCodexOAuth = true
+						source = "stored Codex OAuth credentials"
+					}
+				} else if creds.Type == "api_key" && creds.APIKey != "" {
+					apiKey = creds.APIKey
+					source = "stored API key"
+				}
+			}
+		}
 	}
 
+	// Fall back to environment variable
+	if apiKey == "" {
+		apiKey = os.Getenv("OPENAI_API_KEY")
+		source = "OPENAI_API_KEY environment variable"
+	}
+
+	if apiKey == "" {
+		return nil, fmt.Errorf("OpenAI API key not provided. Use 'kit auth login openai', --provider-api-key flag, or OPENAI_API_KEY environment variable")
+	}
+
+	if os.Getenv("DEBUG") != "" || os.Getenv("KIT_DEBUG") != "" {
+		fmt.Fprintf(os.Stderr, "Using OpenAI API key from: %s\n", source)
+	}
+
+	// For Codex OAuth, use the ChatGPT backend API with custom headers
+	if isCodexOAuth {
+		return createOpenAICodexProvider(ctx, config, modelName, apiKey, accountID)
+	}
+
+	// Regular OpenAI API key flow
 	var opts []openai.Option
 	opts = append(opts, openai.WithAPIKey(apiKey))
 	opts = append(opts, openai.WithUseResponsesAPI())
@@ -643,6 +698,135 @@ func createOpenAIProvider(ctx context.Context, config *ProviderConfig, modelName
 	return &ProviderResult{Model: model, ProviderOptions: providerOpts}, nil
 }
 
+// createOpenAICodexProvider creates a provider for ChatGPT/Codex OAuth tokens.
+// Uses the chatgpt.com/backend-api/codex endpoint with special headers.
+func createOpenAICodexProvider(ctx context.Context, config *ProviderConfig, modelName, token, accountID string) (*ProviderResult, error) {
+	// Check for spark models which are not accessible via OAuth
+	if detectCodexModelFamily(modelName) == "gpt-codex-spark" {
+		return nil, fmt.Errorf("gpt-codex-spark models are not accessible via ChatGPT OAuth. " +
+			"These models require special access or a different authentication method. " +
+			"Please use regular Codex models like 'openai/gpt-5.3-codex' instead")
+	}
+
+	// Use the ChatGPT backend API with /codex path
+	baseURL := "https://chatgpt.com/backend-api/codex"
+	if config.ProviderURL != "" {
+		baseURL = config.ProviderURL
+	}
+
+	// Build custom HTTP client with required headers
+	httpClient := createCodexHTTPClient(token, accountID, config.TLSSkipVerify)
+
+	var opts []openai.Option
+	opts = append(opts, openai.WithAPIKey(token))
+	opts = append(opts, openai.WithBaseURL(baseURL))
+	opts = append(opts, openai.WithUseResponsesAPI())
+	opts = append(opts, openai.WithHTTPClient(httpClient))
+
+	provider, err := openai.New(opts...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create OpenAI Codex provider: %w", err)
+	}
+
+	model, err := provider.LanguageModel(ctx, modelName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create OpenAI Codex model: %w", err)
+	}
+
+	providerOpts := buildCodexProviderOptions(config, modelName)
+
+	return &ProviderResult{
+		Model:               model,
+		ProviderOptions:     providerOpts,
+		SkipMaxOutputTokens: true,
+	}, nil
+}
+
+// buildCodexProviderOptions returns fantasy.ProviderOptions configured for
+// OpenAI Codex API. The Codex API requires the system prompt to be passed
+// as 'instructions' rather than as a system message.
+func buildCodexProviderOptions(config *ProviderConfig, modelName string) fantasy.ProviderOptions {
+	store := false
+	opts := &openai.ResponsesProviderOptions{
+		Store: &store,
+	}
+
+	if config.SystemPrompt != "" {
+		opts.Instructions = &config.SystemPrompt
+	}
+
+	if openai.IsResponsesReasoningModel(modelName) {
+		opts.ReasoningEffort = thinkingLevelToReasoningEffort(config.ThinkingLevel)
+	}
+
+	return fantasy.ProviderOptions{openai.Name: opts}
+}
+
+// detectCodexModelFamily determines the model family from the model name
+func detectCodexModelFamily(modelName string) string {
+	modelName = strings.ToLower(modelName)
+	if strings.Contains(modelName, "spark") {
+		return "gpt-codex-spark"
+	}
+	if strings.Contains(modelName, "codex-mini") || strings.Contains(modelName, "mini-latest") {
+		return "gpt-codex-mini"
+	}
+	if strings.Contains(modelName, "codex") {
+		return "gpt-codex"
+	}
+	return ""
+}
+
+// createCodexHTTPClient creates an HTTP client with headers required for ChatGPT/Codex API
+func createCodexHTTPClient(token, accountID string, skipVerify bool) *http.Client {
+	var base http.RoundTripper
+	if skipVerify {
+		base = &http.Transport{
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: true,
+			},
+		}
+	} else {
+		base = http.DefaultTransport
+	}
+
+	return &http.Client{
+		Transport: &codexTransport{
+			base:      base,
+			token:     token,
+			accountID: accountID,
+		},
+		Timeout: 120 * time.Second,
+	}
+}
+
+// codexTransport is a custom RoundTripper that adds ChatGPT/Codex specific headers
+type codexTransport struct {
+	base      http.RoundTripper
+	token     string
+	accountID string
+}
+
+func (t *codexTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	newReq := req.Clone(req.Context())
+
+	// Add required headers for ChatGPT/Codex API
+	// These headers mimic the official pi client to avoid Cloudflare blocking
+	newReq.Header.Set("Authorization", "Bearer "+t.token)
+	if t.accountID != "" {
+		newReq.Header.Set("chatgpt-account-id", t.accountID)
+	}
+	newReq.Header.Set("originator", "kit")
+	newReq.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36")
+	newReq.Header.Set("OpenAI-Beta", "responses=experimental")
+	newReq.Header.Set("Accept", "text/event-stream")
+	newReq.Header.Set("Accept-Language", "en-US,en;q=0.9")
+	newReq.Header.Set("Cache-Control", "no-cache")
+	newReq.Header.Set("Pragma", "no-cache")
+
+	return t.base.RoundTrip(newReq)
+}
+
 func createGoogleProvider(ctx context.Context, config *ProviderConfig, modelName string) (*ProviderResult, error) {
 	apiKey := firstNonEmpty(
 		config.ProviderAPIKey,
@@ -779,6 +963,42 @@ func createVercelProvider(ctx context.Context, config *ProviderConfig, modelName
 	return &ProviderResult{Model: model}, nil
 }
 
+func createCustomProvider(ctx context.Context, config *ProviderConfig, modelName string) (*ProviderResult, error) {
+	if config.ProviderURL == "" {
+		return nil, fmt.Errorf("custom provider requires --provider-url")
+	}
+
+	apiKey := config.ProviderAPIKey
+	if apiKey == "" {
+		apiKey = os.Getenv("CUSTOM_API_KEY")
+	}
+	if apiKey == "" {
+		// Many local/custom endpoints don't require a key; use a placeholder.
+		apiKey = "custom"
+	}
+
+	var opts []openaicompat.Option
+	opts = append(opts, openaicompat.WithBaseURL(config.ProviderURL))
+	opts = append(opts, openaicompat.WithAPIKey(apiKey))
+	opts = append(opts, openaicompat.WithName("custom"))
+
+	if config.TLSSkipVerify {
+		opts = append(opts, openaicompat.WithHTTPClient(createHTTPClientWithTLSConfig(true)))
+	}
+
+	p, err := openaicompat.New(opts...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create custom provider: %w", err)
+	}
+
+	model, err := p.LanguageModel(ctx, modelName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create custom model: %w", err)
+	}
+
+	return &ProviderResult{Model: model}, nil
+}
+
 func createOllamaProvider(ctx context.Context, config *ProviderConfig, modelName string) (*ProviderResult, error) {
 	baseURL := "http://localhost:11434"
 	if host := os.Getenv("OLLAMA_HOST"); host != "" {

internal/models/registry.go

@@ -22,6 +22,7 @@ type ModelInfo struct {
 	Temperature bool
 	Cost        Cost
 	Limit       Limit
+	ProviderNPM string // Model-specific provider npm override (e.g. "@ai-sdk/anthropic")
 }
 
 // Cost represents the pricing information for a model.
@@ -78,6 +79,10 @@ func buildFromModelsDB() map[string]ProviderInfo {
 	for providerID, dp := range dbProviders {
 		modelsMap := make(map[string]ModelInfo, len(dp.Models))
 		for modelID, dm := range dp.Models {
+			providerNPM := ""
+			if dm.Provider != nil {
+				providerNPM = dm.Provider.NPM
+			}
 			modelsMap[modelID] = ModelInfo{
 				ID:          dm.ID,
 				Name:        dm.Name,
@@ -94,6 +99,7 @@ func buildFromModelsDB() map[string]ProviderInfo {
 					Context: dm.Limit.Context,
 					Output:  dm.Limit.Output,
 				},
+				ProviderNPM: providerNPM,
 			}
 		}
 
@@ -116,6 +122,47 @@ func buildFromModelsDB() map[string]ProviderInfo {
 		}
 	}
 
+	// Register the "custom" provider stub for --provider-url without --model.
+	// This allows users to point kit at any OpenAI-compatible endpoint without
+	// needing to specify a model from the database.
+	providers["custom"] = ProviderInfo{
+		ID:   "custom",
+		Name: "Custom",
+		Models: map[string]ModelInfo{
+			"custom": {
+				ID:          "custom",
+				Name:        "Custom",
+				Attachment:  false,
+				Reasoning:   true,
+				Temperature: true,
+				Cost: Cost{
+					Input:  0,
+					Output: 0,
+				},
+				Limit: Limit{
+					Context: 262_144,
+					Output:  65_536,
+				},
+			},
+		},
+	}
+
+	// Load custom models from config file and merge into custom provider.
+	// Config file models take precedence - if a model ID exists in both
+	// models.dev and config, the config version wins.
+	if customModels := loadCustomModelsFromConfig(); customModels != nil {
+		for modelID, info := range customModels {
+			// Validate custom model config
+			if info.Limit.Context <= 0 {
+				fmt.Fprintf(os.Stderr, "Warning: custom model %q has invalid context limit: %d\n", modelID, info.Limit.Context)
+			}
+			if info.Limit.Output <= 0 {
+				fmt.Fprintf(os.Stderr, "Warning: custom model %q has invalid output limit: %d\n", modelID, info.Limit.Output)
+			}
+			providers["custom"].Models[modelID] = info
+		}
+	}
+
 	return providers
 }
 
@@ -178,6 +225,15 @@ func (r *ModelsRegistry) ValidateEnvironment(provider string, apiKey string) err
 		}
 	}
 
+	// For openai, check stored credentials (OAuth / API key)
+	if provider == "openai" {
+		if cm, err := auth.NewCredentialManager(); err == nil {
+			if has, _ := cm.HasOpenAICredentials(); has {
+				return nil
+			}
+		}
+	}
+
 	envVars, err := r.getRequiredEnvVars(provider)
 	if err != nil {
 		// Unknown provider — nothing to validate

internal/prompts/frontmatter.go

@@ -0,0 +1,25 @@
+package prompts
+
+import (
+	"fmt"
+
+	"gopkg.in/yaml.v3"
+)
+
+// frontmatterSep is the YAML frontmatter delimiter.
+const frontmatterSep = "---"
+
+// Frontmatter represents the YAML frontmatter in a prompt template file.
+type Frontmatter struct {
+	// Description summarises what this template provides.
+	Description string `yaml:"description"`
+}
+
+// ParseFrontmatter parses YAML frontmatter content into a Frontmatter struct.
+func ParseFrontmatter(content string) (*Frontmatter, error) {
+	var fm Frontmatter
+	if err := yaml.Unmarshal([]byte(content), &fm); err != nil {
+		return nil, fmt.Errorf("parsing frontmatter: %w", err)
+	}
+	return &fm, nil
+}

internal/prompts/loader.go

@@ -0,0 +1,217 @@
+package prompts
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/charmbracelet/log"
+)
+
+// LoadOptions configures how templates are discovered and loaded.
+type LoadOptions struct {
+	// Cwd is the current working directory for project-local discovery.
+	// If empty, the current working directory is used.
+	Cwd string
+	// HomeDir is the user's home directory. If empty, os.UserHomeDir() is used.
+	HomeDir string
+	// ExtraPaths are additional explicit paths to search for templates.
+	ExtraPaths []string
+	// ConfigPaths are paths from configuration files to search.
+	ConfigPaths []string
+	// IncludeDefaults determines whether to include built-in default templates.
+	IncludeDefaults bool
+}
+
+// Diagnostic reports a template collision or loading issue.
+type Diagnostic struct {
+	// Name is the template name that had a collision.
+	Name string
+	// KeptPath is the path of the template that was kept (higher precedence).
+	KeptPath string
+	// DroppedPath is the path of the template that was dropped.
+	DroppedPath string
+	// Reason explains why the collision occurred.
+	Reason string
+}
+
+// LoadAll discovers and loads all prompt templates from standard locations
+// and any extra paths. Templates are loaded in order of precedence (lowest
+// to highest), with later templates overriding earlier ones of the same name.
+//
+// Discovery paths searched in order:
+//  1. Default templates (if IncludeDefaults)
+//  2. ~/.kit/prompts/ (global user templates)
+//  3. .kit/prompts/ (project-local templates)
+//  4. ConfigPaths (from configuration)
+//  5. ExtraPaths (explicit paths, highest precedence)
+func LoadAll(opts LoadOptions) ([]*PromptTemplate, []Diagnostic, error) {
+	if opts.Cwd == "" {
+		opts.Cwd, _ = os.Getwd()
+	}
+
+	if opts.HomeDir == "" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return nil, nil, fmt.Errorf("getting home directory: %w", err)
+		}
+		opts.HomeDir = home
+	}
+
+	var all []*PromptTemplate
+	var diagnostics []Diagnostic
+	seen := make(map[string]*PromptTemplate) // name -> template
+
+	// Helper to add templates with deduplication tracking
+	addTemplates := func(templates []*PromptTemplate, source string) {
+		for _, tpl := range templates {
+			if existing, ok := seen[tpl.Name]; ok {
+				// Collision: report diagnostic, keep existing (lower precedence wins)
+				diagnostics = append(diagnostics, Diagnostic{
+					Name:        tpl.Name,
+					KeptPath:    existing.FilePath,
+					DroppedPath: tpl.FilePath,
+					Reason:      fmt.Sprintf("template from %s overridden by %s", source, existing.Source),
+				})
+				log.Debug("template collision",
+					"name", tpl.Name,
+					"dropped", tpl.FilePath,
+					"kept", existing.FilePath)
+			} else {
+				tpl.Source = source
+				seen[tpl.Name] = tpl
+				all = append(all, tpl)
+			}
+		}
+	}
+
+	// 1. Default templates (lowest precedence)
+	if opts.IncludeDefaults {
+		defaults := loadDefaultTemplates()
+		addTemplates(defaults, "default")
+	}
+
+	// 2. Global user templates: ~/.kit/prompts/
+	globalDir := filepath.Join(opts.HomeDir, ".kit", "prompts")
+	if templates, err := LoadFromDir(globalDir); err == nil {
+		addTemplates(templates, "global")
+	}
+
+	// 3. Project-local templates: .kit/prompts/
+	localDir := filepath.Join(opts.Cwd, ".kit", "prompts")
+	if templates, err := LoadFromDir(localDir); err == nil {
+		addTemplates(templates, "local")
+	}
+
+	// 4. Config paths
+	for _, path := range opts.ConfigPaths {
+		info, err := os.Stat(path)
+		if err != nil {
+			continue
+		}
+		if info.IsDir() {
+			if templates, err := LoadFromDir(path); err == nil {
+				addTemplates(templates, "config")
+			}
+		} else if strings.HasSuffix(path, ".md") {
+			if tpl, err := ParseTemplate(path); err == nil {
+				addTemplates([]*PromptTemplate{tpl}, "config")
+			}
+		}
+	}
+
+	// 5. Extra paths (highest precedence)
+	for _, path := range opts.ExtraPaths {
+		info, err := os.Stat(path)
+		if err != nil {
+			continue
+		}
+		if info.IsDir() {
+			if templates, err := LoadFromDir(path); err == nil {
+				addTemplates(templates, "explicit")
+			}
+		} else if strings.HasSuffix(path, ".md") {
+			if tpl, err := ParseTemplate(path); err == nil {
+				addTemplates([]*PromptTemplate{tpl}, "explicit")
+			}
+		}
+	}
+
+	return all, diagnostics, nil
+}
+
+// LoadFromDir scans a directory for .md files and loads them as templates.
+// It looks for *.md files directly in the directory.
+// Files that fail to parse are logged and skipped.
+func LoadFromDir(dir string) ([]*PromptTemplate, error) {
+	info, err := os.Stat(dir)
+	if err != nil || !info.IsDir() {
+		return nil, nil // directory doesn't exist — not an error
+	}
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return nil, fmt.Errorf("reading prompts directory %s: %w", dir, err)
+	}
+
+	var templates []*PromptTemplate
+	var errs []string
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		name := entry.Name()
+		if !strings.HasSuffix(name, ".md") {
+			continue
+		}
+
+		full := filepath.Join(dir, name)
+		tpl, err := ParseTemplate(full)
+		if err != nil {
+			errs = append(errs, err.Error())
+			continue
+		}
+		templates = append(templates, tpl)
+	}
+
+	if len(errs) > 0 {
+		return templates, fmt.Errorf("some templates failed to load: %s", strings.Join(errs, "; "))
+	}
+	return templates, nil
+}
+
+// Deduplicate removes duplicate templates by name, keeping the first occurrence.
+// It returns the deduplicated list and diagnostics for any collisions.
+// This is a standalone function for when you need to deduplicate an existing list.
+func Deduplicate(templates []*PromptTemplate) ([]*PromptTemplate, []Diagnostic) {
+	seen := make(map[string]*PromptTemplate)
+	var result []*PromptTemplate
+	var diagnostics []Diagnostic
+
+	for _, tpl := range templates {
+		if existing, ok := seen[tpl.Name]; ok {
+			diagnostics = append(diagnostics, Diagnostic{
+				Name:        tpl.Name,
+				KeptPath:    existing.FilePath,
+				DroppedPath: tpl.FilePath,
+				Reason:      "duplicate template name (first-match-wins)",
+			})
+		} else {
+			seen[tpl.Name] = tpl
+			result = append(result, tpl)
+		}
+	}
+
+	return result, diagnostics
+}
+
+// loadDefaultTemplates returns the built-in default templates.
+// These are embedded templates that ship with Kit.
+func loadDefaultTemplates() []*PromptTemplate {
+	// Default templates can be added here as needed
+	// For now, return an empty slice - users can define their own templates
+	return nil
+}

internal/prompts/loader_test.go

@@ -0,0 +1,126 @@
+package prompts
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadAll_Integration(t *testing.T) {
+	// Create a temp directory for testing
+	tempDir := t.TempDir()
+
+	// Create the .kit/prompts subdirectory structure
+	promptsDir := filepath.Join(tempDir, ".kit", "prompts")
+	if err := os.MkdirAll(promptsDir, 0755); err != nil {
+		t.Fatalf("Failed to create prompts dir: %v", err)
+	}
+
+	// Create a test template file
+	templateContent := `---
+description: Test template for integration
+---
+Review $1 with focus on $2`
+
+	testFile := filepath.Join(promptsDir, "test.md")
+	if err := os.WriteFile(testFile, []byte(templateContent), 0644); err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+
+	// Test loading from the temp directory
+	tpls, diags, err := LoadAll(LoadOptions{
+		HomeDir:         tempDir,
+		IncludeDefaults: false, // Skip default locations for this test
+	})
+
+	if err != nil {
+		t.Fatalf("LoadAll failed: %v", err)
+	}
+
+	if len(diags) > 0 {
+		t.Logf("Got %d diagnostics", len(diags))
+	}
+
+	if len(tpls) != 1 {
+		t.Fatalf("Expected 1 template, got %d", len(tpls))
+	}
+
+	tpl := tpls[0]
+	if tpl.Name != "test" {
+		t.Errorf("Expected name 'test', got '%s'", tpl.Name)
+	}
+
+	if tpl.Description != "Test template for integration" {
+		t.Errorf("Expected description 'Test template for integration', got '%s'", tpl.Description)
+	}
+
+	// Test expansion
+	expanded := tpl.Expand("code security")
+	expected := "Review code with focus on security"
+	if expanded != expected {
+		t.Errorf("Expected '%s', got '%s'", expected, expanded)
+	}
+}
+
+func TestParseTemplate_WithFrontmatter(t *testing.T) {
+	// Create a temp file with frontmatter
+	tempDir := t.TempDir()
+	templateContent := `---
+description: A test template
+---
+Create a $1 component with $2 features`
+
+	testFile := filepath.Join(tempDir, "component.md")
+	if err := os.WriteFile(testFile, []byte(templateContent), 0644); err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+
+	tpl, err := ParseTemplate(testFile)
+	if err != nil {
+		t.Fatalf("ParseTemplate failed: %v", err)
+	}
+
+	if tpl.Name != "component" {
+		t.Errorf("Expected name 'component', got '%s'", tpl.Name)
+	}
+
+	if tpl.Description != "A test template" {
+		t.Errorf("Expected description 'A test template', got '%s'", tpl.Description)
+	}
+
+	expectedContent := "Create a $1 component with $2 features"
+	if tpl.Content != expectedContent {
+		t.Errorf("Expected content '%s', got '%s'", expectedContent, tpl.Content)
+	}
+}
+
+func TestParseTemplate_WithoutFrontmatter(t *testing.T) {
+	// Create a temp file without frontmatter
+	tempDir := t.TempDir()
+	templateContent := `Simple template without frontmatter
+Supports $1 and $2 placeholders`
+
+	testFile := filepath.Join(tempDir, "simple.md")
+	if err := os.WriteFile(testFile, []byte(templateContent), 0644); err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+
+	tpl, err := ParseTemplate(testFile)
+	if err != nil {
+		t.Fatalf("ParseTemplate failed: %v", err)
+	}
+
+	if tpl.Name != "simple" {
+		t.Errorf("Expected name 'simple', got '%s'", tpl.Name)
+	}
+
+	// Description should be empty since there's no frontmatter
+	if tpl.Description != "" {
+		t.Errorf("Expected empty description, got '%s'", tpl.Description)
+	}
+
+	// Content should include everything
+	if tpl.Content != templateContent {
+		t.Errorf("Content mismatch\nExpected:\n%s\nGot:\n%s", templateContent, tpl.Content)
+	}
+}

internal/prompts/template.go

@@ -0,0 +1,279 @@
+package prompts
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// PromptTemplate is a named prompt template with shell-style argument placeholders.
+// It supports Pi-style $1, $2, $@, $ARGUMENTS, ${@:N}, ${@:N:L} syntax.
+type PromptTemplate struct {
+	// Name is the human-readable identifier for this template.
+	Name string
+	// Description summarises what this template provides.
+	Description string
+	// Content is the raw template text with placeholders.
+	Content string
+	// Source indicates where the template was loaded from (e.g., "default", "user").
+	Source string
+	// FilePath is the absolute filesystem path the template was loaded from.
+	FilePath string
+}
+
+// ParseTemplate reads a template from a file. The template name is derived
+// from the filename (without extension). If the file contains YAML frontmatter,
+// the description is extracted from it.
+func ParseTemplate(path string) (*PromptTemplate, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("reading template %s: %w", path, err)
+	}
+
+	abs, err := filepath.Abs(path)
+	if err != nil {
+		abs = path
+	}
+
+	content := string(data)
+	tpl := &PromptTemplate{
+		FilePath: abs,
+		Content:  content,
+	}
+
+	// Parse frontmatter if present
+	if strings.HasPrefix(strings.TrimSpace(content), frontmatterSep) {
+		trimmed := strings.TrimSpace(content)
+		rest := trimmed[len(frontmatterSep):]
+		frontmatter, body, found := strings.Cut(rest, "\n"+frontmatterSep)
+		if found {
+			body = strings.TrimPrefix(body, "\n")
+			fm, err := ParseFrontmatter(frontmatter)
+			if err == nil {
+				tpl.Description = fm.Description
+			}
+			tpl.Content = strings.TrimSpace(body)
+		}
+	}
+
+	// Derive name from filename
+	base := filepath.Base(path)
+	ext := filepath.Ext(base)
+	tpl.Name = strings.TrimSuffix(base, ext)
+
+	return tpl, nil
+}
+
+// ParseCommandArgs splits a command line into arguments respecting quotes.
+// It handles single quotes, double quotes, and backslash escaping.
+func ParseCommandArgs(input string) []string {
+	var args []string
+	var current strings.Builder
+	inSingleQuote := false
+	inDoubleQuote := false
+	escaped := false
+
+	for i, r := range input {
+		if escaped {
+			current.WriteRune(r)
+			escaped = false
+			continue
+		}
+
+		if r == '\\' && !inSingleQuote {
+			// Backslash escapes next char, but not in single quotes
+			escaped = true
+			continue
+		}
+
+		if r == '\'' && !inDoubleQuote {
+			inSingleQuote = !inSingleQuote
+			continue
+		}
+
+		if r == '"' && !inSingleQuote {
+			inDoubleQuote = !inDoubleQuote
+			continue
+		}
+
+		if r == ' ' && !inSingleQuote && !inDoubleQuote {
+			if current.Len() > 0 {
+				args = append(args, current.String())
+				current.Reset()
+			}
+			continue
+		}
+
+		current.WriteRune(r)
+		_ = i // silence unused warning when we need position later
+	}
+
+	if current.Len() > 0 {
+		args = append(args, current.String())
+	}
+
+	return args
+}
+
+// argPlaceholder matches shell-style argument placeholders:
+//   - $1, $2, etc. - positional arguments
+//   - $@ - all arguments
+//   - $ARGUMENTS - all arguments (alias for $@)
+//   - ${@:N} - arguments from N onwards
+//   - ${@:N:L} - L arguments starting from N
+var argPlaceholder = regexp.MustCompile(`\$\{(\d+)\}|\$\{(\d+):(\d+)\}|\$\{ARGUMENTS\}|\$\{@(:\d+)?(:\d+)?\}|\$(\d+)|\$@|\$ARGUMENTS`)
+
+// SubstituteArgs replaces argument placeholders in content with values from args.
+// Supported placeholders:
+//   - $N, ${N} - the Nth argument (1-indexed)
+//   - $@, $ARGUMENTS, ${ARGUMENTS} - all arguments joined with spaces
+//   - ${@:N} - arguments from index N onwards (0-indexed)
+//   - ${@:N:L} - L arguments starting from index N (0-indexed)
+func SubstituteArgs(content string, args []string) string {
+	return argPlaceholder.ReplaceAllStringFunc(content, func(match string) string {
+		// Check for ${N} or ${N:M} format
+		if strings.HasPrefix(match, "${") && strings.Contains(match, "}") {
+			inner := match[2 : len(match)-1] // Remove ${ and }
+
+			// Check for ${ARGUMENTS}
+			if inner == "ARGUMENTS" {
+				return strings.Join(args, " ")
+			}
+
+			// Check for ${@...} format
+			if strings.HasPrefix(inner, "@") {
+				return expandAtArgs(inner, args)
+			}
+
+			// Check for ${N:M} format (positional with length)
+			if colonIdx := strings.Index(inner, ":"); colonIdx > 0 {
+				startStr := inner[:colonIdx]
+				rest := inner[colonIdx+1:]
+
+				start, err := strconv.Atoi(startStr)
+				if err != nil || start < 1 {
+					return match
+				}
+
+				// Check if there's a second colon for length ${N:M:L}
+				lengthStr, _, ok := strings.Cut(rest, ":")
+				if ok {
+					length, err := strconv.Atoi(lengthStr)
+					if err != nil || length < 0 {
+						return match
+					}
+					return joinArgsRange(args, start-1, length)
+				}
+
+				// Single colon ${N:M} - M is length
+				length, err := strconv.Atoi(rest)
+				if err != nil || length < 0 {
+					return match
+				}
+				return joinArgsRange(args, start-1, length)
+			}
+
+			// Simple ${N} format
+			n, err := strconv.Atoi(inner)
+			if err != nil || n < 1 {
+				return match
+			}
+			if n <= len(args) {
+				return args[n-1]
+			}
+			return ""
+		}
+
+		// Check for $N format (without braces)
+		if strings.HasPrefix(match, "$") && !strings.HasPrefix(match, "${") {
+			suffix := match[1:]
+
+			// $@ or $ARGUMENTS
+			if suffix == "@" || suffix == "ARGUMENTS" {
+				return strings.Join(args, " ")
+			}
+
+			// $N
+			n, err := strconv.Atoi(suffix)
+			if err != nil || n < 1 {
+				return match
+			}
+			if n <= len(args) {
+				return args[n-1]
+			}
+			return ""
+		}
+
+		return match
+	})
+}
+
+// expandAtArgs handles ${@...} patterns (1-indexed like bash)
+func expandAtArgs(inner string, args []string) string {
+	// Remove the @ prefix
+	rest := inner[1:]
+
+	if rest == "" {
+		// ${@} - all arguments
+		return strings.Join(args, " ")
+	}
+
+	// Must start with :
+	if !strings.HasPrefix(rest, ":") {
+		return "${" + inner + "}"
+	}
+	rest = rest[1:]
+
+	// Parse start index
+	startStr, lengthStr, hasLength := strings.Cut(rest, ":")
+
+	start, err := strconv.Atoi(startStr)
+	if err != nil || start < 0 {
+		return "${" + inner + "}"
+	}
+
+	// Convert from 1-indexed to 0-indexed (bash convention)
+	// Treat 0 as 1 (bash convention: args start at 1)
+	if start > 0 {
+		start--
+	}
+
+	if hasLength {
+		length, err := strconv.Atoi(lengthStr)
+		if err != nil || length < 0 {
+			return "${" + inner + "}"
+		}
+		return joinArgsRange(args, start, length)
+	}
+
+	// ${@:N} - from N to end
+	if start >= len(args) {
+		return ""
+	}
+	return strings.Join(args[start:], " ")
+}
+
+// joinArgsRange joins args from start index, taking up to length elements
+func joinArgsRange(args []string, start, length int) string {
+	if start >= len(args) || length <= 0 {
+		return ""
+	}
+	end := start + length
+	end = min(end, len(args))
+	return strings.Join(args[start:end], " ")
+}
+
+// Expand substitutes arguments into the template content and returns the result.
+// It first parses args from the input string, then substitutes them into the template.
+func (t *PromptTemplate) Expand(argsInput string) string {
+	args := ParseCommandArgs(argsInput)
+	return SubstituteArgs(t.Content, args)
+}
+
+// ExpandWithArgs substitutes the provided arguments into the template content.
+func (t *PromptTemplate) ExpandWithArgs(args []string) string {
+	return SubstituteArgs(t.Content, args)
+}

internal/prompts/template_test.go

@@ -0,0 +1,215 @@
+package prompts
+
+import (
+	"testing"
+)
+
+func TestParseCommandArgs(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected []string
+	}{
+		{"", []string{}},
+		{"hello", []string{"hello"}},
+		{"hello world", []string{"hello", "world"}},
+		{`"hello world"`, []string{"hello world"}},
+		{`'hello world'`, []string{"hello world"}},
+		{`hello "world foo" bar`, []string{"hello", "world foo", "bar"}},
+		{`hello 'world foo' bar`, []string{"hello", "world foo", "bar"}},
+		{`hello \"world\"`, []string{"hello", `"world"`}},
+		{`hello \\world`, []string{"hello", `\world`}},
+		{`  hello   world  `, []string{"hello", "world"}},
+		{`Button "onClick handler" "disabled support"`, []string{"Button", "onClick handler", "disabled support"}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			got := ParseCommandArgs(tt.input)
+			if len(got) != len(tt.expected) {
+				t.Errorf("ParseCommandArgs(%q) = %v, want %v", tt.input, got, tt.expected)
+				return
+			}
+			for i := range got {
+				if got[i] != tt.expected[i] {
+					t.Errorf("ParseCommandArgs(%q)[%d] = %q, want %q", tt.input, i, got[i], tt.expected[i])
+				}
+			}
+		})
+	}
+}
+
+func TestSubstituteArgs(t *testing.T) {
+	tests := []struct {
+		name     string
+		content  string
+		args     []string
+		expected string
+	}{
+		{
+			name:     "no placeholders",
+			content:  "Hello world",
+			args:     []string{},
+			expected: "Hello world",
+		},
+		{
+			name:     "positional $1",
+			content:  "Hello $1",
+			args:     []string{"world"},
+			expected: "Hello world",
+		},
+		{
+			name:     "positional $1 $2",
+			content:  "$1 and $2",
+			args:     []string{"first", "second"},
+			expected: "first and second",
+		},
+		{
+			name:     "missing arg",
+			content:  "Hello $1 and $2",
+			args:     []string{"world"},
+			expected: "Hello world and ",
+		},
+		{
+			name:     "$@ wildcard",
+			content:  "Args: $@",
+			args:     []string{"a", "b", "c"},
+			expected: "Args: a b c",
+		},
+		{
+			name:     "$ARGUMENTS wildcard",
+			content:  "Args: $ARGUMENTS",
+			args:     []string{"a", "b", "c"},
+			expected: "Args: a b c",
+		},
+		{
+			name:     "${@} all args",
+			content:  "Args: ${@}",
+			args:     []string{"a", "b", "c"},
+			expected: "Args: a b c",
+		},
+		{
+			name:     "${@:2} slice from index 2",
+			content:  "Rest: ${@:2}",
+			args:     []string{"a", "b", "c", "d"},
+			expected: "Rest: b c d",
+		},
+		{
+			name:     "${@:1:2} slice with length",
+			content:  "First two: ${@:1:2}",
+			args:     []string{"a", "b", "c", "d"},
+			expected: "First two: a b",
+		},
+		{
+			name:     "${@:0} from start",
+			content:  "All: ${@:0}",
+			args:     []string{"a", "b", "c"},
+			expected: "All: a b c",
+		},
+		{
+			name:     "${@:3:1} single arg",
+			content:  "Third: ${@:3:1}",
+			args:     []string{"a", "b", "c", "d"},
+			expected: "Third: c",
+		},
+		{
+			name:     "combined placeholders",
+			content:  "Create $1 with features: $ARGUMENTS",
+			args:     []string{"Button", "onClick", "disabled"},
+			expected: "Create Button with features: Button onClick disabled",
+		},
+		{
+			name:     "slice beyond bounds",
+			content:  "${@:10}",
+			args:     []string{"a", "b"},
+			expected: "",
+		},
+		{
+			name:     "empty args with wildcard",
+			content:  "Args: $@",
+			args:     []string{},
+			expected: "Args: ",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := SubstituteArgs(tt.content, tt.args)
+			if got != tt.expected {
+				t.Errorf("SubstituteArgs(%q, %v) = %q, want %q", tt.content, tt.args, got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestParseFrontmatter(t *testing.T) {
+	tests := []struct {
+		name     string
+		content  string
+		wantDesc string
+		wantErr  bool
+	}{
+		{
+			name:     "simple description",
+			content:  "description: Review code\n",
+			wantDesc: "Review code",
+		},
+		{
+			name:     "empty",
+			content:  "",
+			wantDesc: "",
+		},
+		{
+			name:     "invalid yaml",
+			content:  "description: [unclosed",
+			wantDesc: "",
+			wantErr:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fm, err := ParseFrontmatter(tt.content)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseFrontmatter() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if err != nil {
+				return
+			}
+			if fm.Description != tt.wantDesc {
+				t.Errorf("ParseFrontmatter() Description = %q, want %q", fm.Description, tt.wantDesc)
+			}
+		})
+	}
+}
+
+func TestPromptTemplateExpand(t *testing.T) {
+	tpl := &PromptTemplate{
+		Name:        "component",
+		Description: "Create a component",
+		Content:     "Create a React component named $1 with features: $ARGUMENTS",
+	}
+
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{
+			input:    "Button",
+			expected: "Create a React component named Button with features: Button",
+		},
+		{
+			input:    `Button "onClick handler"`,
+			expected: "Create a React component named Button with features: Button onClick handler",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			got := tpl.Expand(tt.input)
+			if got != tt.expected {
+				t.Errorf("Expand(%q) = %q, want %q", tt.input, got, tt.expected)
+			}
+		})
+	}
+}

internal/session/entry.go

@@ -23,6 +23,7 @@ const (
 	EntryTypeLabel         EntryType = "label"
 	EntryTypeSessionInfo   EntryType = "session_info"
 	EntryTypeExtensionData EntryType = "extension_data"
+	EntryTypeCompaction    EntryType = "compaction"
 )
 
 // CurrentVersion is the session format version for JSONL tree sessions.
@@ -102,6 +103,20 @@ type ExtensionDataEntry struct {
 	Data    string `json:"data"`     // Extension-defined data (JSON or plain text)
 }
 
+// CompactionEntry records an LLM-generated summary of older messages.
+// Instead of deleting old messages, the tree manager skips entries before
+// FirstKeptEntryID when building the LLM context, preserving full history.
+type CompactionEntry struct {
+	Entry
+	Summary          string   `json:"summary"`
+	FirstKeptEntryID string   `json:"first_kept_entry_id"`
+	TokensBefore     int      `json:"tokens_before"`
+	TokensAfter      int      `json:"tokens_after"`
+	MessagesRemoved  int      `json:"messages_removed"`
+	ReadFiles        []string `json:"read_files,omitempty"`
+	ModifiedFiles    []string `json:"modified_files,omitempty"`
+}
+
 // GenerateEntryID creates a unique entry identifier (16 hex chars).
 func GenerateEntryID() string {
 	bytes := make([]byte, 8)
@@ -188,6 +203,20 @@ func NewExtensionDataEntry(parentID, extType, data string) *ExtensionDataEntry {
 	}
 }
 
+// NewCompactionEntry creates a CompactionEntry.
+func NewCompactionEntry(parentID, summary, firstKeptEntryID string, tokensBefore, tokensAfter, messagesRemoved int, readFiles, modifiedFiles []string) *CompactionEntry {
+	return &CompactionEntry{
+		Entry:            NewEntry(EntryTypeCompaction, parentID),
+		Summary:          summary,
+		FirstKeptEntryID: firstKeptEntryID,
+		TokensBefore:     tokensBefore,
+		TokensAfter:      tokensAfter,
+		MessagesRemoved:  messagesRemoved,
+		ReadFiles:        readFiles,
+		ModifiedFiles:    modifiedFiles,
+	}
+}
+
 // --- JSONL marshaling helpers ---
 
 // MarshalEntry serializes any entry to a JSON line (no trailing newline).
@@ -259,6 +288,13 @@ func UnmarshalEntry(data []byte) (any, error) {
 		}
 		return &e, nil
 
+	case EntryTypeCompaction:
+		var e CompactionEntry
+		if err := json.Unmarshal(data, &e); err != nil {
+			return nil, fmt.Errorf("failed to unmarshal compaction entry: %w", err)
+		}
+		return &e, nil
+
 	default:
 		return nil, fmt.Errorf("unknown entry type: %q", env.Type)
 	}

internal/session/store.go

@@ -96,6 +96,7 @@ func ListAllSessions() ([]SessionInfo, error) {
 }
 
 // listSessionsInDir reads all .jsonl files in a directory and extracts session info.
+// Empty sessions (no messages) are automatically cleaned up and not returned.
 func listSessionsInDir(dir string) ([]SessionInfo, error) {
 	if _, err := os.Stat(dir); os.IsNotExist(err) {
 		return nil, nil
@@ -117,6 +118,11 @@ func listSessionsInDir(dir string) ([]SessionInfo, error) {
 		if err != nil {
 			continue // skip malformed session files
 		}
+		// Clean up and skip empty sessions (no messages)
+		if info.MessageCount == 0 {
+			_ = os.Remove(path)
+			continue
+		}
 		sessions = append(sessions, *info)
 	}
 

internal/session/tree_manager.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -128,10 +129,34 @@ func OpenTreeSession(path string) (*TreeManager, error) {
 		filePath:   path,
 	}
 
-	scanner := bufio.NewScanner(strings.NewReader(string(data)))
+	reader := bufio.NewReader(strings.NewReader(string(data)))
 	lineNum := 0
-	for scanner.Scan() {
-		line := scanner.Text()
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			if err == io.EOF {
+				// Process the last line if it's not empty
+				if strings.TrimSpace(line) != "" {
+					lineNum++
+					entry, err := UnmarshalEntry([]byte(line))
+					if err != nil {
+						return nil, fmt.Errorf("line %d: %w", lineNum, err)
+					}
+					if lineNum == 1 {
+						h, ok := entry.(*SessionHeader)
+						if !ok {
+							return nil, fmt.Errorf("first line must be a session header, got %T", entry)
+						}
+						tm.header = *h
+					} else {
+						tm.addEntryToIndex(entry)
+					}
+				}
+				break
+			}
+			return nil, fmt.Errorf("failed to read session file: %w", err)
+		}
+
 		if strings.TrimSpace(line) == "" {
 			continue
 		}
@@ -153,9 +178,6 @@ func OpenTreeSession(path string) (*TreeManager, error) {
 
 		tm.addEntryToIndex(entry)
 	}
-	if err := scanner.Err(); err != nil {
-		return nil, fmt.Errorf("failed to scan session file: %w", err)
-	}
 
 	// Set leaf to the last entry.
 	if len(tm.entries) > 0 {
@@ -298,6 +320,22 @@ func (tm *TreeManager) AppendExtensionData(extType, data string) (string, error)
 	return entry.ID, nil
 }
 
+// AppendCompaction adds a compaction entry to the tree. The entry records
+// the summary and the ID of the first entry that should be preserved in the
+// LLM context. Messages before that entry are replaced by the summary.
+func (tm *TreeManager) AppendCompaction(summary, firstKeptEntryID string, tokensBefore, tokensAfter, messagesRemoved int, readFiles, modifiedFiles []string) (string, error) {
+	tm.mu.Lock()
+	defer tm.mu.Unlock()
+
+	entry := NewCompactionEntry(tm.leafID, summary, firstKeptEntryID, tokensBefore, tokensAfter, messagesRemoved, readFiles, modifiedFiles)
+	if err := tm.appendAndPersist(entry); err != nil {
+		return "", err
+	}
+
+	tm.leafID = entry.ID
+	return entry.ID, nil
+}
+
 // GetExtensionData returns all extension data entries matching the given type,
 // walking the current branch from root to leaf. If extType is empty, all
 // extension data entries on the branch are returned.
@@ -441,8 +479,9 @@ func (tm *TreeManager) GetTree() []*TreeNode {
 // --- Context building ---
 
 // BuildContext walks from the current leaf to the root and returns the
-// conversation messages suitable for sending to the LLM. Branch summaries
-// are converted to user messages to provide context from abandoned branches.
+// conversation messages suitable for sending to the LLM. Compaction entries
+// cause older messages to be replaced by the summary. Branch summaries are
+// converted to user messages to provide context from abandoned branches.
 // Also returns the latest model/provider settings encountered on the path.
 func (tm *TreeManager) BuildContext() (messages []fantasy.Message, provider string, modelID string) {
 	tm.mu.RLock()
@@ -455,7 +494,41 @@ func (tm *TreeManager) BuildContext() (messages []fantasy.Message, provider stri
 	// Walk from leaf to root collecting entries.
 	branch := tm.getBranchLocked(tm.leafID)
 
+	// Find the last compaction entry on this branch — it determines
+	// which older messages are replaced by the summary.
+	var lastCompaction *CompactionEntry
+	for i := len(branch) - 1; i >= 0; i-- {
+		if c, ok := branch[i].(*CompactionEntry); ok {
+			lastCompaction = c
+			break
+		}
+	}
+
+	// If there is a compaction, inject the summary first.
+	if lastCompaction != nil {
+		messages = append(messages, fantasy.Message{
+			Role: fantasy.MessageRoleSystem,
+			Content: []fantasy.MessagePart{
+				fantasy.TextPart{
+					Text: fmt.Sprintf("[Conversation summary — earlier messages were compacted]\n\n%s", lastCompaction.Summary),
+				},
+			},
+		})
+	}
+
+	// Determine whether to skip entries (everything before firstKeptEntryID).
+	skipping := lastCompaction != nil
 	for _, entry := range branch {
+		// Once we reach the first kept entry, stop skipping.
+		if skipping {
+			entryID := tm.entryID(entry)
+			if entryID == lastCompaction.FirstKeptEntryID {
+				skipping = false
+			} else {
+				continue
+			}
+		}
+
 		switch e := entry.(type) {
 		case *MessageEntry:
 			msg, err := e.ToMessage()
@@ -481,6 +554,10 @@ func (tm *TreeManager) BuildContext() (messages []fantasy.Message, provider stri
 		case *ModelChangeEntry:
 			provider = e.Provider
 			modelID = e.ModelID
+
+		case *CompactionEntry:
+			// Already handled above (the last one on the branch).
+			continue
 		}
 	}
 
@@ -551,6 +628,11 @@ func (tm *TreeManager) MessageCount() int {
 	return count
 }
 
+// IsEmpty returns true if the session has no messages (only header).
+func (tm *TreeManager) IsEmpty() bool {
+	return tm.MessageCount() == 0
+}
+
 // Close closes the underlying file handle.
 func (tm *TreeManager) Close() error {
 	tm.mu.Lock()
@@ -563,6 +645,96 @@ func (tm *TreeManager) Close() error {
 	return nil
 }
 
+// GetContextEntryIDs returns the entry IDs corresponding to the fantasy
+// messages returned by BuildContext, in the same order. Each entry ID maps
+// to the session entry that produced the fantasy message at the same index.
+// This is used by compaction to map a cut point index back to an entry ID.
+//
+// Note: A single MessageEntry produces at most one fantasy message. Branch
+// summary entries also produce one message each. The returned slice has the
+// same length as the messages slice from BuildContext (excluding the
+// compaction summary system message, which has no entry ID — it gets the
+// empty string "").
+func (tm *TreeManager) GetContextEntryIDs() []string {
+	tm.mu.RLock()
+	defer tm.mu.RUnlock()
+
+	if tm.leafID == "" {
+		return nil
+	}
+
+	branch := tm.getBranchLocked(tm.leafID)
+
+	// Find the last compaction entry for skip logic.
+	var lastCompaction *CompactionEntry
+	for i := len(branch) - 1; i >= 0; i-- {
+		if c, ok := branch[i].(*CompactionEntry); ok {
+			lastCompaction = c
+			break
+		}
+	}
+
+	var ids []string
+
+	// If there's a compaction summary injected, it has no entry ID.
+	if lastCompaction != nil {
+		ids = append(ids, "") // placeholder for the summary system message
+	}
+
+	skipping := lastCompaction != nil
+	for _, entry := range branch {
+		if skipping {
+			entryID := tm.entryID(entry)
+			if entryID == lastCompaction.FirstKeptEntryID {
+				skipping = false
+			} else {
+				continue
+			}
+		}
+
+		switch e := entry.(type) {
+		case *MessageEntry:
+			msg, err := e.ToMessage()
+			if err != nil {
+				continue
+			}
+			msgs := msg.ToFantasyMessages()
+			for range msgs {
+				ids = append(ids, e.ID)
+			}
+
+		case *BranchSummaryEntry:
+			if e.Summary != "" {
+				ids = append(ids, e.ID)
+			}
+
+		case *CompactionEntry:
+			continue
+		}
+	}
+
+	return ids
+}
+
+// GetLastCompaction returns the most recent CompactionEntry on the current
+// branch, or nil if none exists. Used to carry forward file tracking.
+func (tm *TreeManager) GetLastCompaction() *CompactionEntry {
+	tm.mu.RLock()
+	defer tm.mu.RUnlock()
+
+	if tm.leafID == "" {
+		return nil
+	}
+
+	branch := tm.getBranchLocked(tm.leafID)
+	for i := len(branch) - 1; i >= 0; i-- {
+		if c, ok := branch[i].(*CompactionEntry); ok {
+			return c
+		}
+	}
+	return nil
+}
+
 // --- Legacy bridge ---
 
 // AddFantasyMessages appends multiple fantasy messages as entries. This is
@@ -641,6 +813,8 @@ func (tm *TreeManager) entryID(entry any) string {
 		return e.ID
 	case *ExtensionDataEntry:
 		return e.ID
+	case *CompactionEntry:
+		return e.ID
 	default:
 		return ""
 	}
@@ -661,6 +835,8 @@ func (tm *TreeManager) entryParentID(entry any) string {
 		return e.ParentID
 	case *ExtensionDataEntry:
 		return e.ParentID
+	case *CompactionEntry:
+		return e.ParentID
 	default:
 		return ""
 	}

internal/ui/cli.go

@@ -192,7 +192,8 @@ func (c *CLI) UpdateUsageFromResponse(response *fantasy.Response, inputText stri
 	outputTokens := int(usage.OutputTokens)
 
 	// Validate that the metadata seems reasonable
-	if inputTokens > 0 && outputTokens > 0 {
+	// Use API-reported tokens if input tokens are available (output may be 0 in some cases)
+	if inputTokens > 0 {
 		cacheReadTokens := int(usage.CacheReadTokens)
 		cacheWriteTokens := int(usage.CacheCreationTokens)
 		c.usageTracker.UpdateUsage(inputTokens, outputTokens, cacheReadTokens, cacheWriteTokens)

internal/ui/commands.go

@@ -141,6 +141,27 @@ var SlashCommands = []SlashCommand{
 		Description: "Set a display name for this session",
 		Category:    "Navigation",
 	},
+	{
+		Name:        "/resume",
+		Description: "Open session picker to switch sessions",
+		Category:    "Navigation",
+		Aliases:     []string{"/r"},
+	},
+	{
+		Name:        "/export",
+		Description: "Export session (JSONL by default, or /export path.jsonl)",
+		Category:    "System",
+	},
+	{
+		Name:        "/share",
+		Description: "Share session via GitHub Gist (requires gh CLI)",
+		Category:    "System",
+	},
+	{
+		Name:        "/import",
+		Description: "Import a session from a JSONL file (/import path.jsonl)",
+		Category:    "System",
+	},
 	{
 		Name:        "/session",
 		Description: "Show session info and statistics",

internal/ui/compact_renderer.go

@@ -82,9 +82,20 @@ func (r *CompactRenderer) RenderUserMessage(content string, timestamp time.Time)
 }
 
 // RenderAssistantMessage renders an AI assistant's response in compact format with
-// a distinctive symbol (<) and the model name as label. Empty content is displayed
-// as "(no output)". Returns a UIMessage with formatted content and metadata.
+// a distinctive symbol (<) and the model name as label. Empty content is ignored
+// and returns an empty message. Returns a UIMessage with formatted content and metadata.
 func (r *CompactRenderer) RenderAssistantMessage(content string, timestamp time.Time, modelName string) UIMessage {
+	// Ignore empty responses - don't render anything
+	compactContent := r.formatUserAssistantContent(content)
+	if compactContent == "" {
+		return UIMessage{
+			Type:      AssistantMessage,
+			Content:   "",
+			Height:    0,
+			Timestamp: timestamp,
+		}
+	}
+
 	theme := getTheme()
 	symbol := lipgloss.NewStyle().Foreground(theme.Primary).Render("<")
 
@@ -94,12 +105,6 @@ func (r *CompactRenderer) RenderAssistantMessage(content string, timestamp time.
 	}
 	label := lipgloss.NewStyle().Foreground(theme.Primary).Bold(true).Render(modelName)
 
-	// Format content for assistant messages (preserve formatting, no truncation)
-	compactContent := r.formatUserAssistantContent(content)
-	if compactContent == "" {
-		compactContent = lipgloss.NewStyle().Foreground(theme.Muted).Italic(true).Render("(no output)")
-	}
-
 	// Handle multi-line content
 	lines := strings.Split(compactContent, "\n")
 	var formattedLines []string

internal/ui/input.go

@@ -65,11 +65,33 @@ type InputComponent struct {
 	// hideHint suppresses the "enter submit · ctrl+j..." hint text.
 	hideHint bool
 
+	// agentBusy indicates the agent is currently working. When true, the
+	// hint text shows steering shortcut (Ctrl+S) instead of submit.
+	agentBusy bool
+
 	// pendingImages holds clipboard images attached to the next submission.
 	// Images are added via Ctrl+V and cleared on submit or Ctrl+U.
 	pendingImages []ImageAttachment
+
+	// history stores previously submitted prompts (most recent last).
+	// Limited to maxHistory entries; duplicates of the previous entry are
+	// skipped. Empty strings are never stored.
+	history []string
+	// historyIndex is the current position when browsing history.
+	// When not browsing, historyIndex == len(history).
+	historyIndex int
+	// savedInput holds the user's in-progress text before they started
+	// browsing history, so it can be restored when they press down past
+	// the end of history.
+	savedInput string
+	// browsingHistory is true when the user is navigating history with
+	// up/down arrows. Set to false when they type a character or submit.
+	browsingHistory bool
 }
 
+// maxHistory is the maximum number of prompt entries kept in history.
+const maxHistory = 100
+
 // clipboardImageMsg is the result of an async clipboard image read.
 type clipboardImageMsg struct {
 	image *ImageAttachment
@@ -138,6 +160,7 @@ func (s *InputComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	if s.submitNext {
 		s.submitNext = false
 		value := s.textarea.Value()
+		s.pushHistory(value)
 		s.textarea.SetValue("")
 		s.textarea.CursorEnd()
 		s.showPopup = false
@@ -166,10 +189,47 @@ func (s *InputComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			switch msg.String() {
 			case "ctrl+d", "enter":
 				value := s.textarea.Value()
+				s.pushHistory(value)
 				s.textarea.SetValue("")
 				s.textarea.CursorEnd()
 				s.lastValue = ""
 				return s, s.handleSubmit(value)
+			case "up":
+				// Navigate prompt history backward (older entries).
+				if len(s.history) > 0 {
+					if !s.browsingHistory {
+						// Start browsing — save current input.
+						s.savedInput = s.textarea.Value()
+						s.browsingHistory = true
+						s.historyIndex = len(s.history)
+					}
+					if s.historyIndex > 0 {
+						s.historyIndex--
+						s.textarea.SetValue(s.history[s.historyIndex])
+						s.textarea.CursorEnd()
+						s.lastValue = s.textarea.Value()
+					}
+					return s, nil
+				}
+			case "down":
+				// Navigate prompt history forward (newer entries).
+				if s.browsingHistory {
+					if s.historyIndex < len(s.history)-1 {
+						s.historyIndex++
+						s.textarea.SetValue(s.history[s.historyIndex])
+						s.textarea.CursorEnd()
+						s.lastValue = s.textarea.Value()
+					} else {
+						// Past the end — restore saved input.
+						s.historyIndex = len(s.history)
+						s.browsingHistory = false
+						s.textarea.SetValue(s.savedInput)
+						s.textarea.CursorEnd()
+						s.lastValue = s.textarea.Value()
+						s.savedInput = ""
+					}
+					return s, nil
+				}
 			case "ctrl+v":
 				// Try to read an image from the clipboard asynchronously.
 				return s, readClipboardImageCmd()
@@ -250,6 +310,11 @@ func (s *InputComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		value := s.textarea.Value()
 		if value != s.lastValue {
 			s.lastValue = value
+			// User typed something — exit history browsing mode.
+			if s.browsingHistory {
+				s.browsingHistory = false
+				s.savedInput = ""
+			}
 			lines := strings.Split(value, "\n")
 			line := lines[len(lines)-1] // current line (last line for multi-line)
 
@@ -372,6 +437,34 @@ func (s *InputComponent) handleSubmit(value string) tea.Cmd {
 	}
 }
 
+// pushHistory adds a prompt to the history ring buffer. Empty strings and
+// consecutive duplicates of the last entry are skipped. When the buffer
+// exceeds maxHistory, the oldest entry is dropped.
+func (s *InputComponent) pushHistory(value string) {
+	trimmed := strings.TrimSpace(value)
+	if trimmed == "" {
+		return
+	}
+	// Skip consecutive duplicates.
+	if len(s.history) > 0 && s.history[len(s.history)-1] == trimmed {
+		s.resetHistoryBrowsing()
+		return
+	}
+	s.history = append(s.history, trimmed)
+	if len(s.history) > maxHistory {
+		s.history = s.history[len(s.history)-maxHistory:]
+	}
+	s.resetHistoryBrowsing()
+}
+
+// resetHistoryBrowsing resets the history browsing state so the index
+// points past the end (ready for new input).
+func (s *InputComponent) resetHistoryBrowsing() {
+	s.historyIndex = len(s.history)
+	s.browsingHistory = false
+	s.savedInput = ""
+}
+
 // View implements tea.Model. Renders the title, textarea, autocomplete popup
 // (if visible), and help text.
 func (s *InputComponent) View() tea.View {
@@ -425,7 +518,16 @@ func (s *InputComponent) View() tea.View {
 		// Adapt hint text to available width (accounting for left padding of 3).
 		var hint string
 		availableHintWidth := s.width - 3
-		if availableHintWidth >= 67 {
+		if s.agentBusy {
+			// When the agent is working, show steering shortcut.
+			if availableHintWidth >= 55 {
+				hint = "enter queue • ctrl+s steer • esc esc cancel"
+			} else if availableHintWidth >= 35 {
+				hint = "↵ queue • ^S steer • esc×2 cancel"
+			} else {
+				hint = "^S steer"
+			}
+		} else if availableHintWidth >= 67 {
 			hint = "enter submit • ctrl+j / shift+enter new line • ctrl+v paste image"
 		} else if availableHintWidth >= 40 {
 			hint = "↵ submit • ctrl+j newline • ctrl+v image"

internal/ui/messages.go

@@ -111,14 +111,25 @@ func formatToolParams(toolArgs string, maxWidth int) string {
 		result.WriteString(primaryVal)
 	}
 
-	// Collect remaining parameters (skip large values like file content)
+	// Collect remaining parameters, skipping body-content keys (already
+	// rendered in the tool body) and any values that are too large.
+	bodyKeys := map[string]bool{
+		"content":  true,
+		"old_text": true,
+		"new_text": true,
+		"oldText":  true,
+		"newText":  true,
+		"todos":    true,
+	}
 	var remaining []string
 	for key, val := range params {
 		if key == primaryKey {
 			continue
 		}
+		if bodyKeys[key] {
+			continue
+		}
 		valStr := fmt.Sprintf("%v", val)
-		// Skip very large values (e.g., oldString, newString, content, todos)
 		if len(valStr) > 100 {
 			continue
 		}
@@ -213,22 +224,21 @@ func (r *MessageRenderer) RenderUserMessage(content string, timestamp time.Time)
 
 // RenderAssistantMessage renders an AI assistant's response with left-aligned formatting,
 // including the model name, timestamp, and markdown-rendered content. Empty responses
-// are displayed with a special "Finished without output" message. The message features
-// a colored left border for visual distinction.
+// are ignored and return an empty message. The message features a colored left border
+// for visual distinction.
 func (r *MessageRenderer) RenderAssistantMessage(content string, timestamp time.Time, modelName string) UIMessage {
-	theme := getTheme()
-
-	var messageContent string
+	// Ignore empty responses - don't render anything
 	if strings.TrimSpace(content) == "" {
-		messageContent = lipgloss.NewStyle().
-			Italic(true).
-			Foreground(theme.Muted).
-			Align(lipgloss.Center).
-			Render("Finished without output")
-	} else {
-		messageContent = r.renderMarkdown(content, r.width-8)
+		return UIMessage{
+			Type:      AssistantMessage,
+			Content:   "",
+			Height:    0,
+			Timestamp: timestamp,
+		}
 	}
 
+	theme := getTheme()
+	messageContent := r.renderMarkdown(content, r.width-8)
 	fullContent := strings.TrimSuffix(messageContent, "\n")
 
 	// Left border with Primary (Mauve) color for assistant messages.

internal/ui/model_test.go

@@ -54,6 +54,10 @@ func (s *stubAppController) GetTreeSession() *session.TreeManager {
 	return nil
 }
 
+func (s *stubAppController) SwitchTreeSession(_ *session.TreeManager) {
+	// no-op in tests
+}
+
 func (s *stubAppController) SendEvent(_ tea.Msg) {
 	// no-op in tests
 }
@@ -67,6 +71,11 @@ func (s *stubAppController) RunWithFiles(prompt string, _ []fantasy.FilePart) in
 	return s.queueLen
 }
 
+func (s *stubAppController) Steer(prompt string) int {
+	s.runCalls = append(s.runCalls, prompt)
+	return s.queueLen
+}
+
 // --------------------------------------------------------------------------
 // Stub child components
 // --------------------------------------------------------------------------
@@ -112,15 +121,16 @@ func newTestAppModel(ctrl AppController) (*AppModel, *stubStreamComponent, *stub
 	stream := &stubStreamComponent{}
 	input := &stubInputComponent{}
 	m := &AppModel{
-		state:       stateInput,
-		appCtrl:     ctrl,
-		stream:      stream,
-		input:       input,
-		renderer:    newMessageRenderer(80, false),
-		compactMode: false,
-		modelName:   "test-model",
-		width:       80,
-		height:      24,
+		state:                 stateInput,
+		appCtrl:               ctrl,
+		stream:                stream,
+		input:                 input,
+		renderer:              newMessageRenderer(80, false),
+		compactMode:           false,
+		modelName:             "test-model",
+		width:                 80,
+		height:                24,
+		streamingBashMaxLines: 50, // Initialize buffer cap like NewAppModel does
 	}
 	return m, stream, input
 }
@@ -602,6 +612,133 @@ func TestToolResult_printsAndStartsSpinner(t *testing.T) {
 	}
 }
 
+// TestToolOutputEvent_accumulatesBashOutput verifies that ToolOutputEvent
+// accumulates stdout and stderr lines into the streaming bash output buffers.
+func TestToolOutputEvent_accumulatesBashOutput(t *testing.T) {
+	ctrl := &stubAppController{}
+	m, _, _ := newTestAppModel(ctrl)
+	m.state = stateWorking
+
+	// Send stdout chunk.
+	m = sendMsg(m, app.ToolOutputEvent{
+		ToolCallID: "call-1",
+		ToolName:   "bash",
+		Chunk:      "line one\n",
+		IsStderr:   false,
+	})
+
+	if len(m.streamingBashOutput) != 1 || m.streamingBashOutput[0] != "line one\n" {
+		t.Fatalf("expected streamingBashOutput=['line one\\n'], got %v", m.streamingBashOutput)
+	}
+	if len(m.streamingBashStderr) != 0 {
+		t.Fatalf("expected empty streamingBashStderr, got %v", m.streamingBashStderr)
+	}
+
+	// Send another stdout chunk.
+	m = sendMsg(m, app.ToolOutputEvent{
+		ToolCallID: "call-1",
+		ToolName:   "bash",
+		Chunk:      "line two\n",
+		IsStderr:   false,
+	})
+
+	if len(m.streamingBashOutput) != 2 {
+		t.Fatalf("expected 2 stdout lines, got %d", len(m.streamingBashOutput))
+	}
+
+	// Send stderr chunk.
+	m = sendMsg(m, app.ToolOutputEvent{
+		ToolCallID: "call-1",
+		ToolName:   "bash",
+		Chunk:      "error: something failed\n",
+		IsStderr:   true,
+	})
+
+	if len(m.streamingBashStderr) != 1 {
+		t.Fatalf("expected 1 stderr line, got %d", len(m.streamingBashStderr))
+	}
+	if m.streamingBashStderr[0] != "error: something failed\n" {
+		t.Fatalf("expected stderr 'error: something failed\\n', got %q", m.streamingBashStderr[0])
+	}
+}
+
+// TestToolResult_clearsStreamingBashOutput verifies that ToolResultEvent clears
+// the streaming bash output buffers since the final result will be printed.
+func TestToolResult_clearsStreamingBashOutput(t *testing.T) {
+	ctrl := &stubAppController{}
+	m, _, _ := newTestAppModel(ctrl)
+	m.state = stateWorking
+
+	// Accumulate some bash output.
+	m.streamingBashOutput = []string{"output line"}
+	m.streamingBashStderr = []string{"error line"}
+
+	_, _ = m.Update(app.ToolResultEvent{
+		ToolName: "bash",
+		ToolArgs: `{"cmd":"ls"}`,
+		Result:   "output line\nerror line\n",
+		IsError:  false,
+	})
+
+	if len(m.streamingBashOutput) != 0 {
+		t.Fatalf("expected streamingBashOutput cleared, got %v", m.streamingBashOutput)
+	}
+	if len(m.streamingBashStderr) != 0 {
+		t.Fatalf("expected streamingBashStderr cleared, got %v", m.streamingBashStderr)
+	}
+}
+
+// TestToolCallStarted_extractsBashCommand verifies that ToolCallStartedEvent
+// extracts the bash command from ToolArgs and stores it for the streaming output header.
+func TestToolCallStarted_extractsBashCommand(t *testing.T) {
+	ctrl := &stubAppController{}
+	m, _, _ := newTestAppModel(ctrl)
+	m.state = stateWorking
+
+	// Send ToolCallStartedEvent with bash command.
+	m = sendMsg(m, app.ToolCallStartedEvent{
+		ToolCallID: "call-1",
+		ToolName:   "bash",
+		ToolArgs:   `{"command":"ls -la /home"}`,
+	})
+
+	if m.streamingBashCommand != "ls -la /home" {
+		t.Fatalf("expected streamingBashCommand='ls -la /home', got %q", m.streamingBashCommand)
+	}
+
+	// ToolResultEvent should clear the command.
+	m = sendMsg(m, app.ToolResultEvent{
+		ToolCallID: "call-1",
+		ToolName:   "bash",
+		ToolArgs:   `{"command":"ls -la /home"}`,
+		Result:     "output",
+		IsError:    false,
+	})
+
+	if m.streamingBashCommand != "" {
+		t.Fatalf("expected streamingBashCommand cleared, got %q", m.streamingBashCommand)
+	}
+}
+
+// TestToolCallStarted_nonBashTool_doesNotSetCommand verifies that non-bash tools
+// do not set the streamingBashCommand field.
+func TestToolCallStarted_nonBashTool_doesNotSetCommand(t *testing.T) {
+	ctrl := &stubAppController{}
+	m, _, _ := newTestAppModel(ctrl)
+	m.state = stateWorking
+
+	// Send ToolCallStartedEvent with a non-bash tool.
+	m = sendMsg(m, app.ToolCallStartedEvent{
+		ToolCallID: "call-1",
+		ToolName:   "read",
+		ToolArgs:   `{"file":"/etc/passwd"}`,
+	})
+
+	if m.streamingBashCommand != "" {
+		t.Fatalf("expected streamingBashCommand to remain empty for non-bash tools, got %q", m.streamingBashCommand)
+	}
+}
+
 // TestStepError_printCmd verifies that StepErrorEvent with a non-nil error
 // produces a non-nil cmd (the tea.Println call for the error message).
 func TestStepError_printCmd(t *testing.T) {

internal/ui/preferences.go

@@ -0,0 +1,129 @@
+package ui
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// preferences holds user-mutable runtime state that persists across sessions.
+// Stored at ~/.config/kit/preferences.yml, separate from the declarative
+// .kit.yml config so we never clobber user comments or formatting.
+type preferences struct {
+	Theme         string `yaml:"theme,omitempty"`
+	Model         string `yaml:"model,omitempty"`
+	ThinkingLevel string `yaml:"thinking_level,omitempty"`
+}
+
+// preferencesPath returns ~/.config/kit/preferences.yml.
+// Returns "" if the config directory cannot be determined.
+func preferencesPath() string {
+	cfgDir, err := os.UserConfigDir()
+	if err != nil {
+		return ""
+	}
+	return filepath.Join(cfgDir, "kit", "preferences.yml")
+}
+
+// loadPreferences reads and parses the preferences file.
+// Returns zero-value preferences if the file is missing or invalid.
+func loadPreferences() preferences {
+	path := preferencesPath()
+	if path == "" {
+		return preferences{}
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return preferences{}
+	}
+	var prefs preferences
+	if err := yaml.Unmarshal(data, &prefs); err != nil {
+		return preferences{}
+	}
+	return prefs
+}
+
+// savePreferences atomically writes the preferences file, merging into any
+// existing content. The mutate function receives the current preferences and
+// should modify them in place.
+func savePreferences(mutate func(*preferences)) error {
+	path := preferencesPath()
+	if path == "" {
+		return nil // silently skip if config dir unavailable
+	}
+
+	// Load existing preferences to preserve other fields.
+	var prefs preferences
+	if data, err := os.ReadFile(path); err == nil {
+		_ = yaml.Unmarshal(data, &prefs)
+	}
+
+	mutate(&prefs)
+
+	data, err := yaml.Marshal(&prefs)
+	if err != nil {
+		return err
+	}
+
+	// Ensure parent directory exists.
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+
+	// Atomic write: write to temp file, then rename.
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0o644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}
+
+// ── Theme preference ────────────────────────────────────────────────────────
+
+// LoadThemePreference reads the persisted theme name from preferences.yml.
+// Returns "" if no preference is saved or the file doesn't exist.
+func LoadThemePreference() string {
+	return strings.TrimSpace(loadPreferences().Theme)
+}
+
+// SaveThemePreference persists the theme name to ~/.config/kit/preferences.yml.
+// Preserves other preference fields. Uses atomic write (temp + rename) to
+// avoid corruption from concurrent Kit instances.
+func SaveThemePreference(name string) error {
+	return savePreferences(func(p *preferences) {
+		p.Theme = name
+	})
+}
+
+// ── Model preference ────────────────────────────────────────────────────────
+
+// LoadModelPreference reads the persisted model string (e.g.
+// "anthropic/claude-sonnet-4-5-20250929") from preferences.yml.
+// Returns "" if no preference is saved.
+func LoadModelPreference() string {
+	return strings.TrimSpace(loadPreferences().Model)
+}
+
+// SaveModelPreference persists the model string to preferences.yml.
+func SaveModelPreference(model string) error {
+	return savePreferences(func(p *preferences) {
+		p.Model = model
+	})
+}
+
+// ── Thinking level preference ───────────────────────────────────────────────
+
+// LoadThinkingLevelPreference reads the persisted thinking level from
+// preferences.yml. Returns "" if no preference is saved.
+func LoadThinkingLevelPreference() string {
+	return strings.TrimSpace(loadPreferences().ThinkingLevel)
+}
+
+// SaveThinkingLevelPreference persists the thinking level to preferences.yml.
+func SaveThinkingLevelPreference(level string) error {
+	return savePreferences(func(p *preferences) {
+		p.ThinkingLevel = level
+	})
+}

internal/ui/preferences_test.go

@@ -0,0 +1,180 @@
+package ui
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestSaveAndLoadThemePreference(t *testing.T) {
+	// Use a temp dir as XDG_CONFIG_HOME so we don't touch the real config.
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Initially no preference is saved.
+	if got := LoadThemePreference(); got != "" {
+		t.Fatalf("expected empty preference, got %q", got)
+	}
+
+	// Save a preference.
+	if err := SaveThemePreference("dracula"); err != nil {
+		t.Fatalf("SaveThemePreference: %v", err)
+	}
+
+	// Load it back.
+	if got := LoadThemePreference(); got != "dracula" {
+		t.Fatalf("expected %q, got %q", "dracula", got)
+	}
+
+	// Overwrite with a different theme.
+	if err := SaveThemePreference("nord"); err != nil {
+		t.Fatalf("SaveThemePreference: %v", err)
+	}
+	if got := LoadThemePreference(); got != "nord" {
+		t.Fatalf("expected %q, got %q", "nord", got)
+	}
+
+	// Verify the file exists and is valid YAML.
+	path := filepath.Join(tmp, "kit", "preferences.yml")
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading preferences file: %v", err)
+	}
+	if len(data) == 0 {
+		t.Fatal("preferences file is empty")
+	}
+}
+
+func TestLoadThemePreference_MissingFile(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// No file exists — should return empty string, not error.
+	if got := LoadThemePreference(); got != "" {
+		t.Fatalf("expected empty string for missing file, got %q", got)
+	}
+}
+
+func TestLoadThemePreference_InvalidYAML(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Write invalid YAML.
+	dir := filepath.Join(tmp, "kit")
+	_ = os.MkdirAll(dir, 0o755)
+	_ = os.WriteFile(filepath.Join(dir, "preferences.yml"), []byte(":::bad yaml"), 0o644)
+
+	// Should return empty string, not panic.
+	if got := LoadThemePreference(); got != "" {
+		t.Fatalf("expected empty string for invalid YAML, got %q", got)
+	}
+}
+
+func TestSaveThemePreference_PreservesOtherFields(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Pre-populate with extra content (simulating future fields).
+	dir := filepath.Join(tmp, "kit")
+	_ = os.MkdirAll(dir, 0o755)
+	_ = os.WriteFile(filepath.Join(dir, "preferences.yml"), []byte("theme: old\n"), 0o644)
+
+	// Overwrite theme.
+	if err := SaveThemePreference("catppuccin"); err != nil {
+		t.Fatalf("SaveThemePreference: %v", err)
+	}
+
+	if got := LoadThemePreference(); got != "catppuccin" {
+		t.Fatalf("expected %q, got %q", "catppuccin", got)
+	}
+}
+
+func TestSaveAndLoadModelPreference(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Initially empty.
+	if got := LoadModelPreference(); got != "" {
+		t.Fatalf("expected empty, got %q", got)
+	}
+
+	// Save a model.
+	if err := SaveModelPreference("anthropic/claude-sonnet-4-5-20250929"); err != nil {
+		t.Fatalf("SaveModelPreference: %v", err)
+	}
+	if got := LoadModelPreference(); got != "anthropic/claude-sonnet-4-5-20250929" {
+		t.Fatalf("expected %q, got %q", "anthropic/claude-sonnet-4-5-20250929", got)
+	}
+
+	// Overwrite.
+	if err := SaveModelPreference("openai/gpt-4o"); err != nil {
+		t.Fatalf("SaveModelPreference: %v", err)
+	}
+	if got := LoadModelPreference(); got != "openai/gpt-4o" {
+		t.Fatalf("expected %q, got %q", "openai/gpt-4o", got)
+	}
+}
+
+func TestSaveAndLoadThinkingLevelPreference(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Initially empty.
+	if got := LoadThinkingLevelPreference(); got != "" {
+		t.Fatalf("expected empty, got %q", got)
+	}
+
+	// Save a level.
+	if err := SaveThinkingLevelPreference("medium"); err != nil {
+		t.Fatalf("SaveThinkingLevelPreference: %v", err)
+	}
+	if got := LoadThinkingLevelPreference(); got != "medium" {
+		t.Fatalf("expected %q, got %q", "medium", got)
+	}
+
+	// Overwrite.
+	if err := SaveThinkingLevelPreference("high"); err != nil {
+		t.Fatalf("SaveThinkingLevelPreference: %v", err)
+	}
+	if got := LoadThinkingLevelPreference(); got != "high" {
+		t.Fatalf("expected %q, got %q", "high", got)
+	}
+}
+
+func TestPreferencesPreserveEachOther(t *testing.T) {
+	tmp := t.TempDir()
+	t.Setenv("XDG_CONFIG_HOME", tmp)
+
+	// Save all three preferences.
+	if err := SaveThemePreference("dracula"); err != nil {
+		t.Fatal(err)
+	}
+	if err := SaveModelPreference("anthropic/claude-haiku-3-5-20241022"); err != nil {
+		t.Fatal(err)
+	}
+	if err := SaveThinkingLevelPreference("high"); err != nil {
+		t.Fatal(err)
+	}
+
+	// All three should be preserved.
+	if got := LoadThemePreference(); got != "dracula" {
+		t.Fatalf("theme: expected %q, got %q", "dracula", got)
+	}
+	if got := LoadModelPreference(); got != "anthropic/claude-haiku-3-5-20241022" {
+		t.Fatalf("model: expected %q, got %q", "anthropic/claude-haiku-3-5-20241022", got)
+	}
+	if got := LoadThinkingLevelPreference(); got != "high" {
+		t.Fatalf("thinking_level: expected %q, got %q", "high", got)
+	}
+
+	// Updating one should not affect the others.
+	if err := SaveModelPreference("openai/gpt-4o"); err != nil {
+		t.Fatal(err)
+	}
+	if got := LoadThemePreference(); got != "dracula" {
+		t.Fatalf("theme after model update: expected %q, got %q", "dracula", got)
+	}
+	if got := LoadThinkingLevelPreference(); got != "high" {
+		t.Fatalf("thinking_level after model update: expected %q, got %q", "high", got)
+	}
+}

internal/ui/session_selector.go

@@ -0,0 +1,535 @@
+package ui
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"charm.land/bubbles/v2/key"
+	tea "charm.land/bubbletea/v2"
+	"charm.land/lipgloss/v2"
+
+	"github.com/mark3labs/kit/internal/session"
+)
+
+// SessionSelectedMsg is sent when the user selects a session from the picker.
+type SessionSelectedMsg struct {
+	Path string // absolute path to the JSONL session file
+}
+
+// SessionSelectorCancelledMsg is sent when the user cancels the picker.
+type SessionSelectorCancelledMsg struct{}
+
+// SessionDeletedMsg is sent after a session is deleted so the parent can
+// react (e.g. print a message).
+type SessionDeletedMsg struct {
+	Name string
+}
+
+// SessionScopeMode controls which sessions are shown.
+type SessionScopeMode int
+
+const (
+	SessionScopeCwd SessionScopeMode = iota // current folder only
+	SessionScopeAll                         // all sessions across projects
+)
+
+func (m SessionScopeMode) String() string {
+	if m == SessionScopeAll {
+		return "All"
+	}
+	return "Current Folder"
+}
+
+// SessionFilterMode controls filtering of the session list.
+type SessionFilterMode int
+
+const (
+	SessionFilterAll   SessionFilterMode = iota // show all sessions
+	SessionFilterNamed                          // only named sessions
+)
+
+func (m SessionFilterMode) String() string {
+	if m == SessionFilterNamed {
+		return "Named"
+	}
+	return "All"
+}
+
+// controlCharsRe matches ASCII control characters for stripping from previews.
+var controlCharsRe = regexp.MustCompile(`[\x00-\x1f\x7f]`)
+
+// SessionSelectorComponent is a full-screen Bubble Tea component that lets
+// the user browse and select from available sessions. Modeled after pi's
+// session picker: right-aligned metadata, background-highlighted selection,
+// scope/filter toggles, and inline search.
+type SessionSelectorComponent struct {
+	allSessions []session.SessionInfo
+	cwdSessions []session.SessionInfo
+	filtered    []session.SessionInfo
+
+	cursor int
+	search string
+
+	scope  SessionScopeMode
+	filter SessionFilterMode
+
+	// currentPath is the active session file path for marking it in the list.
+	currentPath string
+
+	width  int
+	height int
+	active bool
+
+	// confirmDelete is non-negative when a delete confirmation is pending.
+	confirmDelete int
+}
+
+// NewSessionSelector creates a session selector. It loads sessions for the
+// current working directory and all sessions across projects. If cwd is
+// empty, only "All" scope is available.
+func NewSessionSelector(cwd string, width, height int) *SessionSelectorComponent {
+	ss := &SessionSelectorComponent{
+		width:         width,
+		height:        height,
+		active:        true,
+		confirmDelete: -1,
+	}
+
+	// Load sessions (errors are swallowed — empty list is fine).
+	if cwd != "" {
+		ss.cwdSessions, _ = session.ListSessions(cwd)
+		ss.scope = SessionScopeCwd
+	}
+	ss.allSessions, _ = session.ListAllSessions()
+
+	if cwd == "" || len(ss.cwdSessions) == 0 {
+		ss.scope = SessionScopeAll
+	}
+
+	ss.rebuildFiltered()
+	return ss
+}
+
+// SetCurrentPath sets the currently active session path so the picker can
+// highlight it in the list.
+func (ss *SessionSelectorComponent) SetCurrentPath(path string) {
+	ss.currentPath = path
+}
+
+// Init implements tea.Model.
+func (ss *SessionSelectorComponent) Init() tea.Cmd {
+	return nil
+}
+
+// Update implements tea.Model.
+func (ss *SessionSelectorComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		ss.width = msg.Width
+		ss.height = msg.Height
+		return ss, nil
+
+	case tea.KeyPressMsg:
+		// Delete confirmation mode.
+		if ss.confirmDelete >= 0 {
+			switch msg.String() {
+			case "y", "Y":
+				idx := ss.confirmDelete
+				ss.confirmDelete = -1
+				if idx < len(ss.filtered) {
+					info := ss.filtered[idx]
+					if err := session.DeleteSession(info.Path); err == nil {
+						name := sessionDisplayName(info)
+						ss.removeSession(info.Path)
+						ss.rebuildFiltered()
+						return ss, func() tea.Msg {
+							return SessionDeletedMsg{Name: name}
+						}
+					}
+				}
+				return ss, nil
+			default:
+				ss.confirmDelete = -1
+				return ss, nil
+			}
+		}
+
+		switch {
+		case key.Matches(msg, key.NewBinding(key.WithKeys("up", "k"))):
+			if ss.cursor > 0 {
+				ss.cursor--
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("down", "j"))):
+			if ss.cursor < len(ss.filtered)-1 {
+				ss.cursor++
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("pgup"))):
+			ss.cursor -= ss.visibleHeight()
+			if ss.cursor < 0 {
+				ss.cursor = 0
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("pgdown"))):
+			ss.cursor += ss.visibleHeight()
+			if ss.cursor >= len(ss.filtered) {
+				ss.cursor = len(ss.filtered) - 1
+			}
+			if ss.cursor < 0 {
+				ss.cursor = 0
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("home"))):
+			ss.cursor = 0
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("end"))):
+			ss.cursor = max(len(ss.filtered)-1, 0)
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("enter"))):
+			if ss.cursor < len(ss.filtered) {
+				info := ss.filtered[ss.cursor]
+				ss.active = false
+				return ss, func() tea.Msg {
+					return SessionSelectedMsg{Path: info.Path}
+				}
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("esc"))):
+			if ss.search != "" {
+				ss.search = ""
+				ss.rebuildFiltered()
+			} else {
+				ss.active = false
+				return ss, func() tea.Msg {
+					return SessionSelectorCancelledMsg{}
+				}
+			}
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("tab"))):
+			if ss.scope == SessionScopeCwd {
+				ss.scope = SessionScopeAll
+			} else {
+				ss.scope = SessionScopeCwd
+			}
+			ss.rebuildFiltered()
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("ctrl+n"))):
+			if ss.filter == SessionFilterAll {
+				ss.filter = SessionFilterNamed
+			} else {
+				ss.filter = SessionFilterAll
+			}
+			ss.rebuildFiltered()
+
+		case key.Matches(msg, key.NewBinding(key.WithKeys("d"))):
+			if ss.cursor < len(ss.filtered) {
+				ss.confirmDelete = ss.cursor
+			}
+			return ss, nil
+
+		default:
+			if msg.Text != "" && len(msg.Text) == 1 {
+				ch := msg.Text[0]
+				if ch >= 32 && ch < 127 {
+					ss.search += string(ch)
+					ss.rebuildFiltered()
+				}
+			}
+			if key.Matches(msg, key.NewBinding(key.WithKeys("backspace"))) && len(ss.search) > 0 {
+				ss.search = ss.search[:len(ss.search)-1]
+				ss.rebuildFiltered()
+			}
+		}
+	}
+	return ss, nil
+}
+
+// View implements tea.Model.
+func (ss *SessionSelectorComponent) View() tea.View {
+	theme := GetTheme()
+	w := ss.width
+	var b strings.Builder
+
+	// ── Header: title + scope badges ─────────────────────────────
+	titleStyle := lipgloss.NewStyle().Bold(true).Foreground(theme.Accent).PaddingLeft(1)
+	b.WriteString(titleStyle.Render(fmt.Sprintf("Resume Session (%s)", ss.scope)))
+	b.WriteString("\n")
+
+	// ── Help / keybindings ───────────────────────────────────────
+	helpStyle := lipgloss.NewStyle().Foreground(theme.Muted).PaddingLeft(1)
+	if w >= 75 {
+		b.WriteString(helpStyle.Render("tab: scope  N: named  D: delete  R: rename  type to search  esc: cancel"))
+	} else if w >= 50 {
+		b.WriteString(helpStyle.Render("tab scope  N named  D del  type to search  esc"))
+	} else {
+		b.WriteString(helpStyle.Render("tab N D esc"))
+	}
+	b.WriteString("\n")
+
+	// ── Search (only shown when active) ──────────────────────────
+	if ss.search != "" {
+		searchStyle := lipgloss.NewStyle().Foreground(theme.Info).PaddingLeft(1)
+		b.WriteString(searchStyle.Render(fmt.Sprintf("> %s", ss.search)))
+		b.WriteString("\n")
+	}
+
+	b.WriteString("\n")
+
+	// ── Delete confirmation ──────────────────────────────────────
+	if ss.confirmDelete >= 0 && ss.confirmDelete < len(ss.filtered) {
+		warnStyle := lipgloss.NewStyle().Foreground(theme.Error).Bold(true).PaddingLeft(1)
+		name := sessionDisplayName(ss.filtered[ss.confirmDelete])
+		b.WriteString(warnStyle.Render(fmt.Sprintf("Delete %q? (y/N)", truncateRunes(name, 40))))
+		b.WriteString("\n")
+	}
+
+	// ── Session list ─────────────────────────────────────────────
+	if len(ss.filtered) == 0 {
+		emptyStyle := lipgloss.NewStyle().Foreground(theme.Muted).PaddingLeft(2)
+		if ss.search != "" {
+			b.WriteString(emptyStyle.Render(fmt.Sprintf("No sessions matching %q", ss.search)))
+		} else if ss.filter == SessionFilterNamed {
+			b.WriteString(emptyStyle.Render("No named sessions. Press N to show all."))
+		} else if ss.scope == SessionScopeCwd {
+			b.WriteString(emptyStyle.Render("No sessions in current folder. Press tab to view all."))
+		} else {
+			b.WriteString(emptyStyle.Render("No sessions found"))
+		}
+		b.WriteString("\n")
+	} else {
+		visH := ss.visibleHeight()
+
+		// Center the cursor in the visible window.
+		startIdx := max(0, min(ss.cursor-visH/2, len(ss.filtered)-visH))
+		endIdx := min(startIdx+visH, len(ss.filtered))
+
+		for i := startIdx; i < endIdx; i++ {
+			info := ss.filtered[i]
+			isCursor := i == ss.cursor
+			isCurrent := info.Path == ss.currentPath
+			isDeleting := i == ss.confirmDelete
+			line := ss.renderEntry(info, isCursor, isCurrent, isDeleting, w)
+			b.WriteString(line)
+			b.WriteString("\n")
+		}
+
+		// Scroll position indicator.
+		if len(ss.filtered) > visH {
+			posStyle := lipgloss.NewStyle().Foreground(theme.Muted).PaddingLeft(2)
+			b.WriteString(posStyle.Render(fmt.Sprintf("(%d/%d)", ss.cursor+1, len(ss.filtered))))
+			b.WriteString("\n")
+		}
+	}
+
+	return tea.NewView(b.String())
+}
+
+// IsActive returns whether the selector is still accepting input.
+func (ss *SessionSelectorComponent) IsActive() bool {
+	return ss.active
+}
+
+// --- Internal helpers ---
+
+func (ss *SessionSelectorComponent) visibleHeight() int {
+	// Reserve: title(1) + help(1) + blank(1) + scroll indicator(1) = 4.
+	// Optional: search(1), delete confirm(1).
+	chrome := 4
+	if ss.search != "" {
+		chrome++
+	}
+	if ss.confirmDelete >= 0 {
+		chrome++
+	}
+	return max(ss.height-chrome, 3)
+}
+
+func (ss *SessionSelectorComponent) rebuildFiltered() {
+	var source []session.SessionInfo
+	if ss.scope == SessionScopeCwd {
+		source = ss.cwdSessions
+	} else {
+		source = ss.allSessions
+	}
+
+	if ss.filter == SessionFilterNamed {
+		var named []session.SessionInfo
+		for _, s := range source {
+			if s.Name != "" {
+				named = append(named, s)
+			}
+		}
+		source = named
+	}
+
+	if ss.search != "" {
+		query := strings.ToLower(ss.search)
+		var matches []session.SessionInfo
+		for _, s := range source {
+			haystack := strings.ToLower(s.Name + " " + s.FirstMessage + " " + s.Cwd)
+			if strings.Contains(haystack, query) {
+				matches = append(matches, s)
+			}
+		}
+		ss.filtered = matches
+	} else {
+		ss.filtered = source
+	}
+
+	if ss.cursor >= len(ss.filtered) {
+		ss.cursor = max(len(ss.filtered)-1, 0)
+	}
+}
+
+func (ss *SessionSelectorComponent) removeSession(path string) {
+	ss.cwdSessions = removeByPath(ss.cwdSessions, path)
+	ss.allSessions = removeByPath(ss.allSessions, path)
+}
+
+func removeByPath(sessions []session.SessionInfo, path string) []session.SessionInfo {
+	result := make([]session.SessionInfo, 0, len(sessions))
+	for _, s := range sessions {
+		if s.Path != path {
+			result = append(result, s)
+		}
+	}
+	return result
+}
+
+// renderEntry renders a single session line with right-aligned metadata.
+// Layout: [cursor 2] [message ...variable...] [padding] [count age] [cwd?]
+func (ss *SessionSelectorComponent) renderEntry(info session.SessionInfo, isCursor, isCurrent, isDeleting bool, width int) string {
+	theme := GetTheme()
+
+	// ── Cursor indicator (2 chars) ───────────────────────────────
+	cursorStr := "  "
+	if isCursor {
+		cursorStr = lipgloss.NewStyle().Foreground(theme.Accent).Render("› ")
+	}
+	const cursorW = 2
+
+	// ── Right part: message count + relative time (+ optional cwd) ──
+	age := relativeTime(info.Modified)
+	msgCount := fmt.Sprintf("%d", info.MessageCount)
+	rightPart := msgCount + " " + age
+	if ss.scope == SessionScopeAll && info.Cwd != "" {
+		shortCwd := shortenPath(info.Cwd)
+		if len(shortCwd) > 25 {
+			shortCwd = "..." + shortCwd[len(shortCwd)-22:]
+		}
+		rightPart = shortCwd + " " + rightPart
+	}
+	rightW := utf8.RuneCountInString(rightPart)
+
+	// ── Message text ─────────────────────────────────────────────
+	displayText := sessionDisplayName(info)
+	// Strip control characters and collapse whitespace.
+	displayText = controlCharsRe.ReplaceAllString(displayText, " ")
+	displayText = strings.Join(strings.Fields(displayText), " ")
+
+	availableForMsg := max(width-cursorW-rightW-2, 10) // 2 for min spacing
+	displayText = truncateRunes(displayText, availableForMsg)
+	msgW := utf8.RuneCountInString(displayText)
+
+	// ── Style the message ────────────────────────────────────────
+	msgStyle := lipgloss.NewStyle()
+	switch {
+	case isDeleting:
+		msgStyle = msgStyle.Foreground(theme.Error)
+	case isCurrent:
+		msgStyle = msgStyle.Foreground(theme.Accent)
+	case info.Name != "":
+		msgStyle = msgStyle.Foreground(theme.Warning)
+	default:
+		msgStyle = msgStyle.Foreground(theme.Text)
+	}
+	if isCursor {
+		msgStyle = msgStyle.Bold(true)
+	}
+
+	styledMsg := msgStyle.Render(displayText)
+
+	// ── Style the right part ─────────────────────────────────────
+	rightColor := theme.Muted
+	if isDeleting {
+		rightColor = theme.Error
+	}
+	styledRight := lipgloss.NewStyle().Foreground(rightColor).Render(rightPart)
+
+	// ── Assemble with spacing ────────────────────────────────────
+	spacing := max(width-cursorW-msgW-rightW, 1)
+
+	line := cursorStr + styledMsg + strings.Repeat(" ", spacing) + styledRight
+
+	// ── Background highlight for selected row ────────────────────
+	if isCursor {
+		// Use a subtle background highlight. We apply it by wrapping the
+		// full line in a style with a background color.
+		bgStyle := lipgloss.NewStyle().
+			Background(theme.Highlight).
+			Width(width)
+		line = bgStyle.Render(line)
+	}
+
+	return line
+}
+
+// --- Package helpers ---
+
+// sessionDisplayName returns the best display string for a session:
+// the name if set, the first message, or a fallback.
+func sessionDisplayName(info session.SessionInfo) string {
+	if info.Name != "" {
+		return info.Name
+	}
+	if info.FirstMessage != "" {
+		return info.FirstMessage
+	}
+	return "(empty session)"
+}
+
+// truncateRunes truncates a string to at most maxRunes runes, appending "..."
+// if truncated.
+func truncateRunes(s string, maxRunes int) string {
+	if maxRunes <= 0 {
+		return ""
+	}
+	runes := []rune(s)
+	if len(runes) <= maxRunes {
+		return s
+	}
+	if maxRunes <= 3 {
+		return string(runes[:maxRunes])
+	}
+	return string(runes[:maxRunes-1]) + "…"
+}
+
+// shortenPath replaces the user's home directory prefix with ~.
+func shortenPath(path string) string {
+	return tildeHome(path)
+}
+
+// relativeTime formats a time as a short relative string like "5m", "2h", "3d".
+func relativeTime(t time.Time) string {
+	d := time.Since(t)
+	switch {
+	case d < time.Minute:
+		return "now"
+	case d < time.Hour:
+		return fmt.Sprintf("%dm", int(d.Minutes()))
+	case d < 24*time.Hour:
+		return fmt.Sprintf("%dh", int(d.Hours()))
+	case d < 7*24*time.Hour:
+		return fmt.Sprintf("%dd", int(d.Hours()/24))
+	case d < 30*24*time.Hour:
+		return fmt.Sprintf("%dw", int(d.Hours()/(24*7)))
+	case d < 365*24*time.Hour:
+		return fmt.Sprintf("%dmo", int(d.Hours()/(24*30)))
+	default:
+		return fmt.Sprintf("%dy", int(d.Hours()/(24*365)))
+	}
+}

internal/ui/stream.go

@@ -484,6 +484,7 @@ func (s *StreamComponent) renderReasoningBlock(reasoning string) string {
 
 	contentStyle := lipgloss.NewStyle().
 		Foreground(theme.Muted).
+		Background(theme.MutedBorder).
 		Italic(true)
 
 	var parts []string
@@ -495,6 +496,7 @@ func (s *StreamComponent) renderReasoningBlock(reasoning string) string {
 		hidden := len(lines) - maxCollapsedLines
 		hintStyle := lipgloss.NewStyle().
 			Foreground(theme.VeryMuted).
+			Background(theme.MutedBorder).
 			Italic(true)
 		parts = append(parts, hintStyle.Render(fmt.Sprintf("... (%d lines hidden)", hidden)))
 		lines = lines[len(lines)-maxCollapsedLines:]
@@ -517,8 +519,8 @@ func (s *StreamComponent) renderReasoningBlock(reasoning string) string {
 		} else {
 			durationStr = fmt.Sprintf("%.1fs", duration.Seconds())
 		}
-		footer := lipgloss.NewStyle().Foreground(theme.VeryMuted).Render("Thought for ") +
-			lipgloss.NewStyle().Foreground(theme.Info).Render(durationStr)
+		footer := lipgloss.NewStyle().Foreground(theme.VeryMuted).Background(theme.MutedBorder).Render("Thought for ") +
+			lipgloss.NewStyle().Foreground(theme.Info).Background(theme.MutedBorder).Render(durationStr)
 		parts = append(parts, footer)
 	}
 

internal/ui/themes.go

@@ -7,11 +7,86 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"strings"
 
 	"gopkg.in/yaml.v3"
 )
 
+// ---------------------------------------------------------------------------
+// Color derivation helpers
+// ---------------------------------------------------------------------------
+
+// parseHexColor parses a "#RRGGBB" hex string into r, g, b components (0-255).
+func parseHexColor(hex string) (r, g, b int) {
+	hex = strings.TrimPrefix(hex, "#")
+	if len(hex) == 6 {
+		if v, err := strconv.ParseUint(hex[0:2], 16, 8); err == nil {
+			r = int(v)
+		}
+		if v, err := strconv.ParseUint(hex[2:4], 16, 8); err == nil {
+			g = int(v)
+		}
+		if v, err := strconv.ParseUint(hex[4:6], 16, 8); err == nil {
+			b = int(v)
+		}
+	}
+	return
+}
+
+// blendHex linearly interpolates between two hex colors by amount (0.0–1.0).
+func blendHex(base, tint string, amount float64) string {
+	br, bg, bb := parseHexColor(base)
+	tr, tg, tb := parseHexColor(tint)
+	clamp := func(v int) int {
+		if v < 0 {
+			return 0
+		}
+		if v > 255 {
+			return 255
+		}
+		return v
+	}
+	r := clamp(int(float64(br)*(1-amount) + float64(tr)*amount))
+	g := clamp(int(float64(bg)*(1-amount) + float64(tg)*amount))
+	b := clamp(int(float64(bb)*(1-amount) + float64(tb)*amount))
+	return fmt.Sprintf("#%02x%02x%02x", r, g, b)
+}
+
+// deriveDiffBg computes diff / code background colors from the theme's
+// background, success, and error hex pairs. Returns an adaptive color for each
+// diff element. The tint amounts are tuned for subtle differentiation.
+func deriveDiffBg(bgPair, successPair, errorPair [2]string) (diffInsert, diffDelete, diffEqual, diffMissing, codeBg, gutterBg, writeBg color.Color) {
+	derive := func(idx int) (color.Color, color.Color, color.Color, color.Color) {
+		bg := bgPair[idx]
+		// Contrast target: darken for light mode (idx 0), lighten for dark (idx 1).
+		contrast := "#000000"
+		if idx == 1 {
+			contrast = "#ffffff"
+		}
+		ins := blendHex(bg, successPair[idx], 0.13)
+		del := blendHex(bg, errorPair[idx], 0.13)
+		eq := blendHex(bg, contrast, 0.05)
+		miss := blendHex(bg, contrast, 0.03)
+		return AdaptiveColor(ins, ins), AdaptiveColor(del, del), AdaptiveColor(eq, eq), AdaptiveColor(miss, miss)
+	}
+
+	// Pick the correct index based on detected background.
+	idx := 0
+	if isDarkBg {
+		idx = 1
+	}
+	insL, delL, eqL, missL := derive(idx)
+	diffInsert = insL
+	diffDelete = delL
+	diffEqual = eqL
+	diffMissing = missL
+	codeBg = eqL
+	gutterBg = missL
+	writeBg = insL
+	return
+}
+
 // ThemeEntry is a named, loadable theme — either built-in or discovered from disk.
 type ThemeEntry struct {
 	Name   string // Display name (filename stem or preset name)
@@ -80,14 +155,9 @@ func makeTheme(p presetColors) Theme {
 		Accent:      acOr(p.accent, ac(p.primary)),
 		Highlight:   acOr(p.highlight, def.Highlight),
 	}
-	// Derive diff/code backgrounds from the base background.
-	t.DiffInsertBg = def.DiffInsertBg
-	t.DiffDeleteBg = def.DiffDeleteBg
-	t.DiffEqualBg = def.DiffEqualBg
-	t.DiffMissingBg = def.DiffMissingBg
-	t.CodeBg = def.CodeBg
-	t.GutterBg = def.GutterBg
-	t.WriteBg = def.WriteBg
+	// Derive diff/code backgrounds from the theme's own palette.
+	t.DiffInsertBg, t.DiffDeleteBg, t.DiffEqualBg, t.DiffMissingBg,
+		t.CodeBg, t.GutterBg, t.WriteBg = deriveDiffBg(p.background, p.success, p.error_)
 	// Markdown colors.
 	t.Markdown = MarkdownThemeColors{
 		Text:    t.Text,
@@ -439,7 +509,23 @@ func LoadThemeByName(name string) (Theme, error) {
 }
 
 // ApplyTheme loads a theme by name and sets it as the active global theme.
+// The selection is persisted to ~/.config/kit/preferences.yml so it survives
+// across sessions. Persistence errors are silently ignored — the theme is
+// still applied in-memory even if the write fails.
 func ApplyTheme(name string) error {
+	t, err := LoadThemeByName(name)
+	if err != nil {
+		return err
+	}
+	SetTheme(t)
+	_ = SaveThemePreference(name)
+	return nil
+}
+
+// ApplyThemeWithoutSave loads a theme by name and sets it as the active global
+// theme without persisting the choice. Used at startup to restore a previously
+// saved preference without redundantly re-writing it.
+func ApplyThemeWithoutSave(name string) error {
 	t, err := LoadThemeByName(name)
 	if err != nil {
 		return err
@@ -593,6 +679,17 @@ func loadThemeFile(path string) (Theme, error) {
 
 func fileConfigToTheme(cfg themeFileConfig) Theme {
 	def := DefaultTheme()
+
+	// Resolve the base background/success/error hex pairs for diff derivation.
+	// We need the raw hex strings to feed deriveDiffBg.
+	bgPair := resolveHexPair(cfg.Background, [2]string{"#F0F0F0", "#0D0D0D"})
+	successPair := resolveHexPair(cfg.Success, [2]string{"#998800", "#CCAA00"})
+	errorPair := resolveHexPair(cfg.Error, [2]string{"#CC0000", "#FF3333"})
+
+	// Derive diff backgrounds from the theme's own palette.
+	derivedInsert, derivedDelete, derivedEqual, derivedMissing,
+		derivedCodeBg, derivedGutterBg, derivedWriteBg := deriveDiffBg(bgPair, successPair, errorPair)
+
 	return Theme{
 		Primary:     cfg.Primary.resolve(def.Primary),
 		Secondary:   cfg.Secondary.resolve(def.Secondary),
@@ -611,13 +708,13 @@ func fileConfigToTheme(cfg themeFileConfig) Theme {
 		Accent:      cfg.Accent.resolve(def.Accent),
 		Highlight:   cfg.Highlight.resolve(def.Highlight),
 
-		DiffInsertBg:  cfg.DiffInsertBg.resolve(def.DiffInsertBg),
-		DiffDeleteBg:  cfg.DiffDeleteBg.resolve(def.DiffDeleteBg),
-		DiffEqualBg:   cfg.DiffEqualBg.resolve(def.DiffEqualBg),
-		DiffMissingBg: cfg.DiffMissingBg.resolve(def.DiffMissingBg),
-		CodeBg:        cfg.CodeBg.resolve(def.CodeBg),
-		GutterBg:      cfg.GutterBg.resolve(def.GutterBg),
-		WriteBg:       cfg.WriteBg.resolve(def.WriteBg),
+		DiffInsertBg:  cfg.DiffInsertBg.resolve(derivedInsert),
+		DiffDeleteBg:  cfg.DiffDeleteBg.resolve(derivedDelete),
+		DiffEqualBg:   cfg.DiffEqualBg.resolve(derivedEqual),
+		DiffMissingBg: cfg.DiffMissingBg.resolve(derivedMissing),
+		CodeBg:        cfg.CodeBg.resolve(derivedCodeBg),
+		GutterBg:      cfg.GutterBg.resolve(derivedGutterBg),
+		WriteBg:       cfg.WriteBg.resolve(derivedWriteBg),
 
 		Markdown: MarkdownThemeColors{
 			Text:    cfg.Markdown.Text.resolve(def.Markdown.Text),
@@ -635,3 +732,17 @@ func fileConfigToTheme(cfg themeFileConfig) Theme {
 		},
 	}
 }
+
+// resolveHexPair returns the hex pair from an adaptiveColorPair, falling back
+// to defaults when the pair is empty.
+func resolveHexPair(a adaptiveColorPair, fallback [2]string) [2]string {
+	light := a.Light
+	if light == "" {
+		light = fallback[0]
+	}
+	dark := a.Dark
+	if dark == "" {
+		dark = fallback[1]
+	}
+	return [2]string{light, dark}
+}

internal/ui/themes_test.go

@@ -0,0 +1,85 @@
+package ui
+
+import (
+	"testing"
+)
+
+func TestParseHexColor(t *testing.T) {
+	tests := []struct {
+		hex     string
+		r, g, b int
+	}{
+		{"#000000", 0, 0, 0},
+		{"#ffffff", 255, 255, 255},
+		{"#1e1e2e", 0x1e, 0x1e, 0x2e},
+		{"#a6e3a1", 0xa6, 0xe3, 0xa1},
+		{"#f38ba8", 0xf3, 0x8b, 0xa8},
+	}
+	for _, tt := range tests {
+		r, g, b := parseHexColor(tt.hex)
+		if r != tt.r || g != tt.g || b != tt.b {
+			t.Errorf("parseHexColor(%q) = (%d,%d,%d), want (%d,%d,%d)",
+				tt.hex, r, g, b, tt.r, tt.g, tt.b)
+		}
+	}
+}
+
+func TestBlendHex(t *testing.T) {
+	// Blending with 0 amount should return the base color.
+	got := blendHex("#1e1e2e", "#a6e3a1", 0.0)
+	if got != "#1e1e2e" {
+		t.Errorf("blendHex with 0.0 = %q, want #1e1e2e", got)
+	}
+
+	// Blending with 1.0 amount should return the tint color.
+	got = blendHex("#1e1e2e", "#a6e3a1", 1.0)
+	if got != "#a6e3a1" {
+		t.Errorf("blendHex with 1.0 = %q, want #a6e3a1", got)
+	}
+
+	// Blending black and white at 0.5 should give mid gray.
+	got = blendHex("#000000", "#ffffff", 0.5)
+	// 127 = int(0 + 255*0.5) — truncated, so #7f7f7f
+	if got != "#7f7f7f" {
+		t.Errorf("blendHex black/white at 0.5 = %q, want #7f7f7f", got)
+	}
+}
+
+func TestDeriveDiffBgProducesDifferentColorsPerTheme(t *testing.T) {
+	// Catppuccin palette
+	catBg := [2]string{"#eff1f5", "#1e1e2e"}
+	catSuccess := [2]string{"#40a02b", "#a6e3a1"}
+	catError := [2]string{"#d20f39", "#f38ba8"}
+
+	// KITT palette
+	kittBg := [2]string{"#F0F0F0", "#0D0D0D"}
+	kittSuccess := [2]string{"#998800", "#CCAA00"}
+	kittError := [2]string{"#CC0000", "#FF3333"}
+
+	catInsert, catDelete, _, _, _, _, _ := deriveDiffBg(catBg, catSuccess, catError)
+	kittInsert, kittDelete, _, _, _, _, _ := deriveDiffBg(kittBg, kittSuccess, kittError)
+
+	if catInsert == kittInsert {
+		t.Error("catppuccin DiffInsertBg should differ from kitt DiffInsertBg")
+	}
+	if catDelete == kittDelete {
+		t.Error("catppuccin DiffDeleteBg should differ from kitt DiffDeleteBg")
+	}
+}
+
+func TestMakeThemeDerivesUniqueDiffColors(t *testing.T) {
+	themes := builtinThemes()
+	kitt := themes["kitt"]
+	cat := themes["catppuccin"]
+
+	// The catppuccin diff backgrounds should NOT equal the kitt defaults.
+	if cat.DiffInsertBg == kitt.DiffInsertBg {
+		t.Error("catppuccin DiffInsertBg should differ from kitt default")
+	}
+	if cat.DiffDeleteBg == kitt.DiffDeleteBg {
+		t.Error("catppuccin DiffDeleteBg should differ from kitt default")
+	}
+	if cat.DiffEqualBg == kitt.DiffEqualBg {
+		t.Error("catppuccin DiffEqualBg should differ from kitt default")
+	}
+}

internal/ui/tool_renderers.go

@@ -14,6 +14,7 @@ import (
 	"github.com/alecthomas/chroma/v2/lexers"
 	"github.com/alecthomas/chroma/v2/styles"
 	udiff "github.com/aymanbagabas/go-udiff"
+	xansi "github.com/charmbracelet/x/ansi"
 )
 
 // Maximum visible lines per tool type before truncation.
@@ -22,6 +23,7 @@ const (
 	maxCodeLines  = 20 // lines for Read / code blocks
 	maxWriteLines = 10 // lines for Write blocks
 	maxBashLines  = 20 // lines for Bash output (matches Read)
+	maxLsLines    = 20 // lines for Ls directory listings
 )
 
 // renderToolBody dispatches to tool-specific body renderers based on tool name.
@@ -228,7 +230,7 @@ func renderDiffBlock(before, after string, startLine int, width int) string {
 	gutterMissing := lipgloss.NewStyle().Background(theme.DiffMissingBg)
 
 	contentInsert := lipgloss.NewStyle().Background(theme.DiffInsertBg)
-	contentDelete := lipgloss.NewStyle().Background(theme.DiffDeleteBg).Strikethrough(true)
+	contentDelete := lipgloss.NewStyle().Background(theme.DiffDeleteBg)
 	contentEqual := lipgloss.NewStyle().Foreground(theme.Muted).Background(theme.DiffEqualBg)
 	contentMissing := lipgloss.NewStyle().Background(theme.DiffMissingBg)
 
@@ -314,6 +316,13 @@ func renderLsBody(toolResult string, width int) string {
 
 	lines := strings.Split(content, "\n")
 
+	// Truncate to maxLsLines for display
+	var hiddenCount int
+	if len(lines) > maxLsLines {
+		hiddenCount = len(lines) - maxLsLines
+		lines = lines[:maxLsLines]
+	}
+
 	const indent = "  "
 	codeWidth := max(width-len(indent), 20)
 
@@ -322,10 +331,19 @@ func renderLsBody(toolResult string, width int) string {
 
 	var result []string
 	for _, line := range lines {
+		// Truncate before styling to prevent wrapping.
+		line = truncateLine(line, codeWidth-1) // account for PaddingLeft(1)
 		styled := codeStyle.Width(codeWidth).Render(line)
 		result = append(result, indent+styled)
 	}
 
+	if hiddenCount > 0 {
+		hint := fmt.Sprintf("...(%d more entries)", hiddenCount)
+		hintContent := codeStyle.Width(codeWidth).
+			Foreground(theme.Muted).Italic(true).Render(hint)
+		result = append(result, indent+hintContent)
+	}
+
 	return strings.Join(result, "\n")
 }
 
@@ -431,7 +449,8 @@ func renderCodeBlock(content, fileName string, width int) string {
 		// If this line has no line number, it's a metadata/footer line (e.g. truncation notice).
 		if p.lineNum == "" {
 			// Render footer lines with code background but no gutter
-			footer := codeStyle.Width(codeWidth).Render(p.code)
+			truncatedFooter := truncateLine(p.code, codeWidth-1) // account for PaddingLeft(1)
+			footer := codeStyle.Width(codeWidth).Render(truncatedFooter)
 			emptyGutter := gutterStyle.Width(gutterWidth).Render("")
 			result = append(result, codeIndent+lipgloss.JoinHorizontal(lipgloss.Top, emptyGutter, footer))
 			continue
@@ -445,6 +464,9 @@ func renderCodeBlock(content, fileName string, width int) string {
 		} else {
 			codePart = p.code
 		}
+		// Truncate the (possibly ANSI-highlighted) line to fit within
+		// the code column, preventing lipgloss from wrapping it.
+		codePart = truncateLine(codePart, codeWidth-1) // account for PaddingLeft(1)
 		styledCode := codeStyle.Width(codeWidth).Render(codePart)
 
 		result = append(result, codeIndent+lipgloss.JoinHorizontal(lipgloss.Top, gutter, styledCode))
@@ -528,6 +550,9 @@ func renderWriteBlock(content, fileName string, width int) string {
 		} else {
 			codePart = line
 		}
+		// Truncate the (possibly ANSI-highlighted) line to fit within
+		// the code column, preventing lipgloss from wrapping it.
+		codePart = truncateLine(codePart, codeWidth-1) // account for PaddingLeft(1)
 		styledCode := writeStyle.Width(codeWidth).Render(codePart)
 
 		result = append(result, codeIndent+lipgloss.JoinHorizontal(lipgloss.Top, gutter, styledCode))
@@ -578,9 +603,16 @@ func renderBashBody(toolResult string, width int) string {
 	}
 
 	const lineIndent = "  "
+	// Truncate individual lines to the available width so they never wrap.
+	// This mirrors Crush's approach: truncate, don't wrap.
+	lineWidth := max(width-len(lineIndent), 20)
+	// Account for PaddingLeft(1) on the output/stderr styles
+	maxLineChars := lineWidth - 1
+
 	var rendered []string
 	inStderr := false
 	for _, line := range lines {
+		line = truncateLine(line, maxLineChars)
 		// Detect the STDERR: label that Kit's bash tool emits
 		if strings.TrimSpace(line) == "STDERR:" {
 			inStderr = true
@@ -682,23 +714,28 @@ func syntaxHighlight(source, fileName string) string {
 // Helpers
 // ---------------------------------------------------------------------------
 
-// padRight pads s with spaces to exactly width characters.
+// padRight pads s with spaces to exactly width visual characters.
+// This is ANSI-aware: it measures the visual width of s (ignoring escape
+// codes and accounting for wide characters) before padding or truncating.
 func padRight(s string, width int) string {
-	if len(s) >= width {
-		return s[:width]
+	w := xansi.StringWidth(s)
+	if w >= width {
+		return xansi.Truncate(s, width, "")
 	}
-	return s + strings.Repeat(" ", width-len(s))
+	return s + strings.Repeat(" ", width-w)
 }
 
-// truncateLine truncates a line to maxWidth, adding "…" if truncated.
+// truncateLine truncates a line to maxWidth visual characters, adding "…"
+// if truncated. This is ANSI-aware: escape codes are preserved and wide
+// characters are measured correctly.
 func truncateLine(s string, maxWidth int) string {
-	if len(s) <= maxWidth {
+	if xansi.StringWidth(s) <= maxWidth {
 		return s
 	}
 	if maxWidth < 2 {
-		return s[:maxWidth]
+		return xansi.Truncate(s, maxWidth, "")
 	}
-	return s[:maxWidth-1] + "…"
+	return xansi.Truncate(s, maxWidth, "…")
 }
 
 // ---------------------------------------------------------------------------
@@ -858,12 +895,10 @@ func renderBashCompact(toolResult string, width int) string {
 		display = display[:maxLines]
 	}
 
-	// Truncate each line to available width
+	// Truncate each line to available width (ANSI-aware)
 	lineMax := max(width-4, 20)
 	for i, line := range display {
-		if len(line) > lineMax {
-			display[i] = line[:lineMax-3] + "..."
-		}
+		display[i] = truncateLine(line, lineMax)
 	}
 
 	summary := strings.Join(display, "\n")
@@ -940,10 +975,8 @@ func extractSubagentPreview(content string, maxLines, maxWidth int) string {
 			continue
 		}
 
-		// Truncate long lines
-		if len(trimmed) > maxWidth {
-			trimmed = trimmed[:maxWidth-3] + "..."
-		}
+		// Truncate long lines (ANSI-aware)
+		trimmed = truncateLine(trimmed, maxWidth)
 		preview = append(preview, trimmed)
 
 		if len(preview) >= maxLines {

internal/ui/tree_selector.go

@@ -430,6 +430,8 @@ func (ts *TreeSelectorComponent) renderNode(node FlatNode, isCursor, isLeaf bool
 		}
 	case *session.BranchSummaryEntry:
 		style = lipgloss.NewStyle().Foreground(theme.Warning).Italic(true)
+	case *session.CompactionEntry:
+		style = lipgloss.NewStyle().Foreground(theme.Info).Italic(true)
 	default:
 		style = lipgloss.NewStyle().Foreground(theme.Muted)
 	}
@@ -483,6 +485,13 @@ func (ts *TreeSelectorComponent) entryDisplayText(entry any) string {
 		}
 		return fmt.Sprintf("branch summary: %s", summary)
 
+	case *session.CompactionEntry:
+		summary := e.Summary
+		if len(summary) > 60 {
+			summary = summary[:60] + "..."
+		}
+		return fmt.Sprintf("compaction: %s", summary)
+
 	case *session.LabelEntry:
 		return fmt.Sprintf("label: %s", e.Label)
 

internal/ui/usage_tracker.go

@@ -266,3 +266,14 @@ func (ut *UsageTracker) SetWidth(width int) {
 	defer ut.mu.Unlock()
 	ut.width = width
 }
+
+// UpdateModelInfo updates the model information and OAuth status when the model
+// is switched mid-session. This ensures token costs and context limits are
+// calculated correctly for the new model.
+func (ut *UsageTracker) UpdateModelInfo(modelInfo *models.ModelInfo, provider string, isOAuth bool) {
+	ut.mu.Lock()
+	defer ut.mu.Unlock()
+	ut.modelInfo = modelInfo
+	ut.provider = provider
+	ut.isOAuth = isOAuth
+}

pkg/kit/auth.go

@@ -9,6 +9,10 @@ type CredentialManager = auth.CredentialManager
 // and API key authentication methods.
 type AnthropicCredentials = auth.AnthropicCredentials
 
+// OpenAICredentials holds OpenAI API credentials supporting both OAuth
+// and API key authentication methods.
+type OpenAICredentials = auth.OpenAICredentials
+
 // CredentialStore holds all stored credentials for various providers.
 type CredentialStore = auth.CredentialStore
 
@@ -42,3 +46,34 @@ func GetAnthropicAPIKey() string {
 	}
 	return key
 }
+
+// HasOpenAICredentials checks if valid OpenAI credentials are stored
+// (either OAuth token or API key).
+func HasOpenAICredentials() bool {
+	cm, err := auth.NewCredentialManager()
+	if err != nil {
+		return false
+	}
+	has, err := cm.HasOpenAICredentials()
+	if err != nil {
+		return false
+	}
+	return has
+}
+
+// GetOpenAIAPIKey resolves the OpenAI API key using the standard
+// resolution order: stored credentials -> OPENAI_API_KEY env var.
+// Returns an empty string if no key is found.
+func GetOpenAIAPIKey() string {
+	cm, err := auth.NewCredentialManager()
+	if err != nil {
+		return ""
+	}
+	// Try to get valid access token (handles OAuth refresh)
+	token, err := cm.GetValidOpenAIAccessToken()
+	if err == nil && token != "" {
+		return token
+	}
+	// Fall back to environment variable
+	return ""
+}

pkg/kit/compaction.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 
+	"charm.land/fantasy"
+
 	"github.com/mark3labs/kit/internal/compaction"
 )
 
@@ -83,8 +85,10 @@ func (m *Kit) GetContextStats() ContextStats {
 // customInstructions is optional text appended to the summary prompt (e.g.
 // "Focus on the API design decisions"). Pass "" for the default prompt.
 //
-// After compaction, the tree session is cleared and replaced with the
-// compacted messages (summary + preserved recent messages).
+// Compaction is non-destructive: a CompactionEntry is appended to the session
+// tree recording the summary and the first kept entry ID. Old messages remain
+// on disk but are skipped when building the LLM context — the summary is
+// injected in their place.
 func (m *Kit) Compact(ctx context.Context, opts *CompactionOptions, customInstructions string) (*CompactionResult, error) {
 	return m.compactInternal(ctx, opts, customInstructions, false)
 }
@@ -112,7 +116,7 @@ func (m *Kit) compactInternal(ctx context.Context, opts *CompactionOptions, cust
 		return nil, fmt.Errorf("cannot compact: need at least 2 messages")
 	}
 
-	// Run before-compact hook — extensions can cancel compaction.
+	// Run before-compact hook — extensions can cancel or provide a custom summary.
 	if m.beforeCompact.hasHooks() {
 		stats := m.GetContextStats()
 		if hookResult := m.beforeCompact.run(BeforeCompactHook{
@@ -121,17 +125,32 @@ func (m *Kit) compactInternal(ctx context.Context, opts *CompactionOptions, cust
 			UsagePercent:    stats.UsagePercent,
 			MessageCount:    stats.MessageCount,
 			IsAutomatic:     isAutomatic,
-		}); hookResult != nil && hookResult.Cancel {
-			reason := hookResult.Reason
-			if reason == "" {
-				reason = "compaction cancelled by extension"
+		}); hookResult != nil {
+			if hookResult.Cancel {
+				reason := hookResult.Reason
+				if reason == "" {
+					reason = "compaction cancelled by extension"
+				}
+				return nil, fmt.Errorf("%s", reason)
 			}
-			return nil, fmt.Errorf("%s", reason)
+			// Extension provided a custom summary — use it directly.
+			if hookResult.Summary != "" {
+				return m.applyCustomCompaction(hookResult.Summary, messages, opts)
+			}
+		}
+	}
+
+	// Carry forward file tracking from previous compaction.
+	var prev *compaction.PreviousCompaction
+	if lastCompaction := m.treeSession.GetLastCompaction(); lastCompaction != nil {
+		prev = &compaction.PreviousCompaction{
+			ReadFiles:     lastCompaction.ReadFiles,
+			ModifiedFiles: lastCompaction.ModifiedFiles,
 		}
 	}
 
 	model := m.agent.GetModel()
-	result, newMessages, err := compaction.Compact(ctx, model, messages, *opts, customInstructions)
+	result, _, err := compaction.Compact(ctx, model, messages, *opts, customInstructions, prev)
 	if err != nil {
 		return nil, err
 	}
@@ -139,11 +158,82 @@ func (m *Kit) compactInternal(ctx context.Context, opts *CompactionOptions, cust
 		return nil, nil
 	}
 
-	// Replace the session contents with the compacted messages.
-	// Reset the tree leaf and re-add the compacted messages.
-	m.treeSession.ResetLeaf()
-	if err := m.treeSession.AddFantasyMessages(newMessages); err != nil {
-		return nil, fmt.Errorf("failed to persist compacted messages: %w", err)
+	// Non-destructive: append a CompactionEntry to the session tree instead
+	// of clearing and rewriting messages.
+	entryIDs := m.treeSession.GetContextEntryIDs()
+	firstKeptEntryID := ""
+	if result.CutPoint >= 0 && result.CutPoint < len(entryIDs) {
+		firstKeptEntryID = entryIDs[result.CutPoint]
+	}
+
+	if _, err := m.treeSession.AppendCompaction(
+		result.Summary,
+		firstKeptEntryID,
+		result.OriginalTokens,
+		result.CompactedTokens,
+		result.MessagesRemoved,
+		result.ReadFiles,
+		result.ModifiedFiles,
+	); err != nil {
+		return nil, fmt.Errorf("failed to persist compaction entry: %w", err)
+	}
+
+	m.events.emit(CompactionEvent{
+		Summary:         result.Summary,
+		OriginalTokens:  result.OriginalTokens,
+		CompactedTokens: result.CompactedTokens,
+		MessagesRemoved: result.MessagesRemoved,
+		ReadFiles:       result.ReadFiles,
+		ModifiedFiles:   result.ModifiedFiles,
+	})
+
+	return result, nil
+}
+
+// applyCustomCompaction handles compaction when an extension provides a
+// custom summary. It still determines the cut point and persists a
+// CompactionEntry.
+func (m *Kit) applyCustomCompaction(summary string, messages []fantasy.Message, opts *CompactionOptions) (*CompactionResult, error) {
+	originalTokens := compaction.EstimateMessageTokens(messages)
+
+	cutPoint := compaction.FindCutPoint(messages, opts.KeepRecentTokens)
+	if cutPoint == 0 {
+		cutPoint = len(messages) - 1
+		if cutPoint < 1 {
+			return nil, nil
+		}
+	}
+
+	entryIDs := m.treeSession.GetContextEntryIDs()
+	firstKeptEntryID := ""
+	if cutPoint >= 0 && cutPoint < len(entryIDs) {
+		firstKeptEntryID = entryIDs[cutPoint]
+	}
+
+	// Estimate new token count.
+	summaryTokens := compaction.EstimateMessageTokens([]fantasy.Message{{
+		Role:    "system",
+		Content: []fantasy.MessagePart{fantasy.TextPart{Text: summary}},
+	}})
+	recentTokens := compaction.EstimateMessageTokens(messages[cutPoint:])
+	compactedTokens := summaryTokens + recentTokens
+
+	if _, err := m.treeSession.AppendCompaction(
+		summary,
+		firstKeptEntryID,
+		originalTokens,
+		compactedTokens,
+		cutPoint,
+		nil, nil, // no file tracking for custom summaries
+	); err != nil {
+		return nil, fmt.Errorf("failed to persist compaction entry: %w", err)
+	}
+
+	result := &CompactionResult{
+		Summary:         summary,
+		OriginalTokens:  originalTokens,
+		CompactedTokens: compactedTokens,
+		MessagesRemoved: cutPoint,
 	}
 
 	m.events.emit(CompactionEvent{

pkg/kit/events.go

@@ -39,6 +39,12 @@ const (
 	EventCompaction EventType = "compaction"
 	// EventReasoningDelta fires for each streaming reasoning/thinking chunk.
 	EventReasoningDelta EventType = "reasoning_delta"
+	// EventToolOutput fires when a tool produces streaming output chunks.
+	EventToolOutput EventType = "tool_output"
+	EventStepUsage  EventType = "step_usage"
+	// EventSteerConsumed fires when one or more steering messages have been
+	// injected into the agent turn via PrepareStep.
+	EventSteerConsumed EventType = "steer_consumed"
 )
 
 // ---------------------------------------------------------------------------
@@ -143,6 +149,17 @@ type ReasoningDeltaEvent struct {
 // EventType implements Event.
 func (e ReasoningDeltaEvent) EventType() EventType { return EventReasoningDelta }
 
+// ToolOutputEvent fires when a tool produces streaming output chunks (e.g., bash output).
+type ToolOutputEvent struct {
+	ToolCallID string
+	ToolName   string
+	Chunk      string
+	IsStderr   bool
+}
+
+// EventType implements Event.
+func (e ToolOutputEvent) EventType() EventType { return EventToolOutput }
+
 // MessageEndEvent fires when the assistant message is complete.
 type MessageEndEvent struct {
 	Content string
@@ -236,17 +253,42 @@ type ResponseEvent struct {
 // EventType implements Event.
 func (e ResponseEvent) EventType() EventType { return EventResponse }
 
+// StepUsageEvent fires after each complete step in a multi-step agent turn,
+// carrying the token usage for that specific step. This enables real-time
+// cost tracking during long-running tool-calling conversations.
+type StepUsageEvent struct {
+	InputTokens      uint64
+	OutputTokens     uint64
+	CacheReadTokens  uint64
+	CacheWriteTokens uint64
+}
+
+// EventType implements Event.
+func (e StepUsageEvent) EventType() EventType { return EventStepUsage }
+
 // CompactionEvent fires after a successful compaction.
 type CompactionEvent struct {
 	Summary         string
 	OriginalTokens  int
 	CompactedTokens int
 	MessagesRemoved int
+	ReadFiles       []string
+	ModifiedFiles   []string
 }
 
 // EventType implements Event.
 func (e CompactionEvent) EventType() EventType { return EventCompaction }
 
+// SteerConsumedEvent fires when one or more steering messages have been
+// injected into the agent turn via PrepareStep. The Count indicates how
+// many messages were consumed in this batch.
+type SteerConsumedEvent struct {
+	Count int
+}
+
+// EventType implements Event.
+func (e SteerConsumedEvent) EventType() EventType { return EventSteerConsumed }
+
 // ---------------------------------------------------------------------------
 // EventBus
 // ---------------------------------------------------------------------------
@@ -320,6 +362,16 @@ func (m *Kit) OnToolResult(handler func(ToolResultEvent)) func() {
 	})
 }
 
+// OnToolOutput registers a handler that fires only for ToolOutputEvent
+// (streaming tool output chunks, e.g., from bash). Returns an unsubscribe function.
+func (m *Kit) OnToolOutput(handler func(ToolOutputEvent)) func() {
+	return m.Subscribe(func(e Event) {
+		if to, ok := e.(ToolOutputEvent); ok {
+			handler(to)
+		}
+	})
+}
+
 // OnStreaming registers a handler that fires only for MessageUpdateEvent
 // (streaming text chunks). Returns an unsubscribe function.
 func (m *Kit) OnStreaming(handler func(MessageUpdateEvent)) func() {
@@ -359,3 +411,78 @@ func (m *Kit) OnTurnEnd(handler func(TurnEndEvent)) func() {
 		}
 	})
 }
+
+// ---------------------------------------------------------------------------
+// Subagent event subscriptions
+// ---------------------------------------------------------------------------
+
+// subagentListenerSet holds per-tool-call listeners for subagent events.
+type subagentListenerSet struct {
+	mu        sync.RWMutex
+	listeners map[int]EventListener
+	nextID    int
+}
+
+func newSubagentListenerSet() *subagentListenerSet {
+	return &subagentListenerSet{listeners: make(map[int]EventListener)}
+}
+
+func (s *subagentListenerSet) add(listener EventListener) func() {
+	s.mu.Lock()
+	id := s.nextID
+	s.nextID++
+	s.listeners[id] = listener
+	s.mu.Unlock()
+	return func() {
+		s.mu.Lock()
+		delete(s.listeners, id)
+		s.mu.Unlock()
+	}
+}
+
+func (s *subagentListenerSet) emit(event Event) {
+	s.mu.RLock()
+	snapshot := make([]EventListener, 0, len(s.listeners))
+	for _, l := range s.listeners {
+		snapshot = append(snapshot, l)
+	}
+	s.mu.RUnlock()
+	for _, l := range snapshot {
+		l(event)
+	}
+}
+
+// SubscribeSubagent registers a listener for real-time events from a subagent
+// identified by its tool call ID. Returns an unsubscribe function.
+//
+// The listener receives the same event types as Subscribe() (ToolCallEvent,
+// MessageUpdateEvent, etc.) but scoped to the child agent's activity. If the
+// tool call ID doesn't correspond to an active or future spawn_subagent call,
+// the listener simply never fires.
+//
+// Typical usage — register inside an OnToolCall handler:
+//
+//	kit.OnToolCall(func(e kit.ToolCallEvent) {
+//	    if e.ToolName == "spawn_subagent" {
+//	        kit.SubscribeSubagent(e.ToolCallID, func(child kit.Event) {
+//	            // real-time subagent events
+//	        })
+//	    }
+//	})
+func (m *Kit) SubscribeSubagent(toolCallID string, listener EventListener) func() {
+	actual, _ := m.subagentListeners.LoadOrStore(toolCallID, newSubagentListenerSet())
+	return actual.(*subagentListenerSet).add(listener)
+}
+
+// getSubagentListenerSet returns the listener set for a tool call, or nil.
+func (m *Kit) getSubagentListenerSet(toolCallID string) *subagentListenerSet {
+	if v, ok := m.subagentListeners.Load(toolCallID); ok {
+		return v.(*subagentListenerSet)
+	}
+	return nil
+}
+
+// cleanupSubagentListeners removes the listener set for a completed tool call.
+func (m *Kit) cleanupSubagentListeners(toolCallID string) {
+	m.subagentListeners.Delete(toolCallID)
+}

pkg/kit/extensions_bridge.go

@@ -2,6 +2,7 @@ package kit
 
 import (
 	"strings"
+	"sync"
 
 	"charm.land/fantasy"
 	"github.com/mark3labs/kit/internal/extensions"
@@ -86,6 +87,20 @@ func (m *Kit) bridgeExtensions(runner *extensions.Runner) {
 		})
 	}
 
+	// Tool output streaming events (observation only).
+	if runner.HasHandlers(extensions.ToolOutput) {
+		m.Subscribe(func(e Event) {
+			if ev, ok := e.(ToolOutputEvent); ok {
+				_, _ = runner.Emit(extensions.ToolOutputEvent{
+					ToolCallID: ev.ToolCallID,
+					ToolName:   ev.ToolName,
+					Chunk:      ev.Chunk,
+					IsStderr:   ev.IsStderr,
+				})
+			}
+		})
+	}
+
 	if runner.HasHandlers(extensions.AgentEnd) {
 		m.Subscribe(func(e Event) {
 			if ev, ok := e.(TurnEndEvent); ok {
@@ -105,6 +120,125 @@ func (m *Kit) bridgeExtensions(runner *extensions.Runner) {
 		})
 	}
 
+	// --- Subagent lifecycle events ---
+	// When an extension registers OnSubagentStart/Chunk/End handlers, bridge
+	// the SDK's per-subagent event stream (SubscribeSubagent) into the
+	// extension runner.
+	//
+	// Flow:
+	//   ToolExecutionStartEvent(spawn_subagent) → emit SubagentStartEvent
+	//                                           → SubscribeSubagent → emit SubagentChunkEvents
+	//   ToolResultEvent(spawn_subagent)         → emit SubagentEndEvent
+	//
+	// We use ToolExecutionStart (not ToolCall) for SubagentStart because that
+	// is when the subagent actually begins running. We use ToolResult for
+	// SubagentEnd because that carries the final response text.
+	wantsSubagent := runner.HasHandlers(extensions.SubagentStart) ||
+		runner.HasHandlers(extensions.SubagentChunk) ||
+		runner.HasHandlers(extensions.SubagentEnd)
+
+	if wantsSubagent {
+		// taskByCallID tracks the task description extracted from ToolCall input,
+		// keyed by toolCallID. Populated on ToolCall, consumed on ToolResult.
+		taskByCallID := make(map[string]string)
+		var taskMu = &taskMutex{}
+
+		// Intercept ToolCall to capture the task and subscribe to child events.
+		m.Subscribe(func(e Event) {
+			ev, ok := e.(ToolCallEvent)
+			if !ok || ev.ToolName != "spawn_subagent" {
+				return
+			}
+
+			// Extract task from parsed args.
+			task := ""
+			if ev.ParsedArgs != nil {
+				if t, ok := ev.ParsedArgs["task"].(string); ok {
+					task = t
+				}
+			}
+			taskMu.set(taskByCallID, ev.ToolCallID, task)
+
+			// Subscribe to child events so we can forward them as SubagentChunkEvents.
+			if runner.HasHandlers(extensions.SubagentChunk) {
+				m.SubscribeSubagent(ev.ToolCallID, func(childEvent Event) {
+					chunk := extensions.SubagentChunkEvent{
+						ToolCallID: ev.ToolCallID,
+						Task:       task,
+					}
+					switch ce := childEvent.(type) {
+					case MessageUpdateEvent:
+						chunk.ChunkType = "text"
+						chunk.Content = ce.Chunk
+					case TurnStartEvent:
+						chunk.ChunkType = "turn_start"
+					case TurnEndEvent:
+						chunk.ChunkType = "turn_end"
+					case ToolCallEvent:
+						chunk.ChunkType = "tool_call"
+						chunk.ToolName = ce.ToolName
+						chunk.ToolArgs = ce.ToolArgs
+					case ToolExecutionStartEvent:
+						chunk.ChunkType = "tool_execution_start"
+						chunk.ToolName = ce.ToolName
+					case ToolExecutionEndEvent:
+						chunk.ChunkType = "tool_execution_end"
+						chunk.ToolName = ce.ToolName
+					case ToolResultEvent:
+						chunk.ChunkType = "tool_result"
+						chunk.ToolName = ce.ToolName
+						chunk.ToolResult = ce.Result
+						chunk.IsError = ce.IsError
+					default:
+						return // skip unknown event types
+					}
+					_, _ = runner.Emit(chunk)
+				})
+			}
+		})
+
+		// Emit SubagentStartEvent when execution begins.
+		if runner.HasHandlers(extensions.SubagentStart) {
+			m.Subscribe(func(e Event) {
+				ev, ok := e.(ToolExecutionStartEvent)
+				if !ok || ev.ToolName != "spawn_subagent" {
+					return
+				}
+				task := taskMu.get(taskByCallID, ev.ToolCallID)
+				_, _ = runner.Emit(extensions.SubagentStartEvent{
+					ToolCallID: ev.ToolCallID,
+					Task:       task,
+				})
+			})
+		}
+
+		// Emit SubagentEndEvent when the tool result arrives.
+		if runner.HasHandlers(extensions.SubagentEnd) {
+			m.Subscribe(func(e Event) {
+				ev, ok := e.(ToolResultEvent)
+				if !ok || ev.ToolName != "spawn_subagent" {
+					return
+				}
+				task := taskMu.get(taskByCallID, ev.ToolCallID)
+				taskMu.del(taskByCallID, ev.ToolCallID)
+				errMsg := ""
+				if ev.IsError {
+					errMsg = ev.Result
+				}
+				response := ""
+				if !ev.IsError {
+					response = ev.Result
+				}
+				_, _ = runner.Emit(extensions.SubagentEndEvent{
+					ToolCallID: ev.ToolCallID,
+					Task:       task,
+					Response:   response,
+					ErrorMsg:   errMsg,
+				})
+			})
+		}
+	}
+
 	// --- Context filtering hook ---
 	// Extension ContextPrepare → SDK ContextPrepare hook.
 	if runner.HasHandlers(extensions.ContextPrepare) {
@@ -173,13 +307,44 @@ func (m *Kit) bridgeExtensions(runner *extensions.Runner) {
 				MessageCount:    h.MessageCount,
 				IsAutomatic:     h.IsAutomatic,
 			})
-			if r, ok := result.(extensions.BeforeCompactResult); ok && r.Cancel {
-				return &BeforeCompactResult{
-					Cancel: true,
-					Reason: r.Reason,
+			if r, ok := result.(extensions.BeforeCompactResult); ok {
+				if r.Cancel {
+					return &BeforeCompactResult{
+						Cancel: true,
+						Reason: r.Reason,
+					}
+				}
+				if r.Summary != "" {
+					return &BeforeCompactResult{
+						Summary: r.Summary,
+					}
 				}
 			}
 			return nil
 		})
 	}
 }
+
+// taskMutex is a simple mutex-protected map helper used by bridgeExtensions.
+// It lives in this file to avoid polluting the kit package with unexported types.
+type taskMutex struct {
+	mu sync.Mutex
+}
+
+func (t *taskMutex) set(m map[string]string, key, val string) {
+	t.mu.Lock()
+	m[key] = val
+	t.mu.Unlock()
+}
+
+func (t *taskMutex) get(m map[string]string, key string) string {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return m[key]
+}
+
+func (t *taskMutex) del(m map[string]string, key string) {
+	t.mu.Lock()
+	delete(m, key)
+	t.mu.Unlock()
+}

pkg/kit/hooks.go

@@ -107,12 +107,18 @@ type BeforeCompactHook struct {
 	IsAutomatic bool
 }
 
-// BeforeCompactResult controls whether compaction proceeds.
+// BeforeCompactResult controls whether compaction proceeds. Extensions can
+// cancel compaction or provide a custom summary that replaces the default
+// LLM-generated one.
 type BeforeCompactResult struct {
 	// Cancel, when true, prevents compaction from proceeding.
 	Cancel bool
 	// Reason is a human-readable explanation when Cancel is true.
 	Reason string
+	// Summary, when non-empty, replaces the default LLM-generated summary.
+	// The extension is responsible for generating a useful summary.
+	// Ignored when Cancel is true.
+	Summary string
 }
 
 // ---------------------------------------------------------------------------

pkg/kit/kit.go

@@ -62,6 +62,17 @@ type Kit struct {
 	// tool definitions, etc.
 	lastInputTokensMu sync.RWMutex
 	lastInputTokens   int
+
+	// subagentListeners holds per-tool-call event listeners registered via
+	// SubscribeSubagent(). Keyed by toolCallID → *subagentListenerSet.
+	subagentListeners sync.Map
+
+	// steerCh is a buffered channel used to inject steering messages into
+	// the running agent turn via Fantasy's PrepareStep. Created fresh for
+	// each generate() call and set to nil when idle. Protected by steerMu.
+	steerMu       sync.Mutex
+	steerCh       chan string
+	leftoverSteer []string // unconsumed steer messages from the last turn
 }
 
 // Subscribe registers an EventListener that will be called for every lifecycle
@@ -525,8 +536,11 @@ func (m *Kit) SetModel(ctx context.Context, modelString string) error {
 	}
 
 	// Build a provider config from current settings, overriding the model.
+	// Load system prompt properly (handles both file paths and inline content).
+	systemPrompt, _ := config.LoadSystemPrompt(viper.GetString("system-prompt"))
 	config := &models.ProviderConfig{
 		ModelString:    modelString,
+		SystemPrompt:   systemPrompt,
 		ProviderAPIKey: viper.GetString("provider-api-key"),
 		ProviderURL:    viper.GetString("provider-url"),
 		MaxTokens:      viper.GetInt("max-tokens"),
@@ -913,8 +927,12 @@ func New(ctx context.Context, opts *Options) (*Kit, error) {
 	setSDKDefaults()
 
 	// Initialize config (loads config files and env vars).
-	if err := InitConfig(opts.ConfigFile, false); err != nil {
-		return nil, fmt.Errorf("failed to initialize config: %w", err)
+	// Only initialize if not already done (e.g., by CLI's cobra.OnInitialize).
+	// Check if model is already set, which indicates config was loaded.
+	if viper.GetString("model") == "" {
+		if err := InitConfig(opts.ConfigFile, false); err != nil {
+			return nil, fmt.Errorf("failed to initialize config: %w", err)
+		}
 	}
 
 	// Handle CLI debug mode.
@@ -1397,21 +1415,56 @@ func (m *Kit) Subagent(ctx context.Context, cfg SubagentConfig) (*SubagentResult
 // All prompt modes (Prompt, Steer, FollowUp, PromptWithOptions) share this
 // single code path so callback wiring is never duplicated.
 func (m *Kit) generate(ctx context.Context, messages []fantasy.Message) (*agent.GenerateWithLoopResult, error) {
+	// Create a per-turn steer channel and attach it to the context so the
+	// agent's PrepareStep can inject steering messages between steps.
+	steerCh := make(chan string, 16)
+	m.steerMu.Lock()
+	m.steerCh = steerCh
+	m.steerMu.Unlock()
+	defer func() {
+		// Drain any unconsumed steer messages before nilling the channel.
+		// These are stored in leftoverSteer so DrainSteer() can return them.
+		var leftover []string
+		for {
+			select {
+			case msg := <-steerCh:
+				leftover = append(leftover, msg)
+			default:
+				goto drained
+			}
+		}
+	drained:
+		m.steerMu.Lock()
+		m.steerCh = nil
+		m.leftoverSteer = leftover
+		m.steerMu.Unlock()
+	}()
+	ctx = agent.ContextWithSteerCh(ctx, steerCh)
+	ctx = agent.ContextWithSteerConsumed(ctx, func(count int) {
+		m.events.emit(SteerConsumedEvent{Count: count})
+	})
+
 	// Inject the in-process subagent spawner into the context so the
 	// spawn_subagent core tool can create child Kit instances without
 	// importing pkg/kit (which would create an import cycle).
 	ctx = core.WithSubagentSpawner(ctx, func(
-		spawnCtx context.Context, prompt, model, systemPrompt string, timeout time.Duration,
+		spawnCtx context.Context, toolCallID, prompt, model, systemPrompt string, timeout time.Duration,
 	) (*core.SubagentSpawnResult, error) {
+		// Build OnEvent: dispatch to per-tool-call listeners if any are
+		// registered via SubscribeSubagent(). Listeners are cleaned up
+		// after the subagent completes.
+		var onEvent func(Event)
+		if listeners := m.getSubagentListenerSet(toolCallID); listeners != nil {
+			onEvent = listeners.emit
+		}
 		result, err := m.Subagent(spawnCtx, SubagentConfig{
 			Prompt:       prompt,
 			Model:        model,
 			SystemPrompt: systemPrompt,
 			Timeout:      timeout,
-			OnEvent: func(e Event) {
-				m.events.emit(e)
-			},
+			OnEvent:      onEvent,
 		})
+		m.cleanupSubagentListeners(toolCallID)
 		if result == nil {
 			return &core.SubagentSpawnResult{Error: err}, err
 		}
@@ -1468,6 +1521,24 @@ func (m *Kit) generate(ctx context.Context, messages []fantasy.Message) (*agent.
 		func(delta string) {
 			m.events.emit(ReasoningDeltaEvent{Delta: delta})
 		},
+		func(toolCallID, toolName, chunk string, isStderr bool) {
+			// Emit tool output chunk event for streaming bash output
+			m.events.emit(ToolOutputEvent{
+				ToolCallID: toolCallID,
+				ToolName:   toolName,
+				Chunk:      chunk,
+				IsStderr:   isStderr,
+			})
+		},
+		func(inputTokens, outputTokens, cacheReadTokens, cacheCreationTokens int64) {
+			// Emit step usage event for real-time cost tracking
+			m.events.emit(StepUsageEvent{
+				InputTokens:      uint64(inputTokens),
+				OutputTokens:     uint64(outputTokens),
+				CacheReadTokens:  uint64(cacheReadTokens),
+				CacheWriteTokens: uint64(cacheCreationTokens),
+			})
+		},
 	)
 }
 
@@ -1554,9 +1625,13 @@ func (m *Kit) runTurn(ctx context.Context, promptLabel string, prompt string, pr
 
 	result, err := m.generate(ctx, messages)
 	if err != nil {
-		// Persist any messages that were generated during this turn (tool calls,
-		// tool results) even if the generation was cancelled. This ensures that
-		// partial progress like completed tool executions are not lost.
+		// Persist any messages from completed steps (tool call/result
+		// pairs) so partial progress is not lost. The agent layer only
+		// includes fully-paired tool_use + tool_result messages in
+		// completedStepMessages, so there are no orphaned entries that
+		// would break subsequent API requests. The user message and any
+		// completed work remain in the session; only the in-progress
+		// (pending) message or tool call is discarded.
 		if result != nil && len(result.ConversationMessages) > sentCount {
 			for _, msg := range result.ConversationMessages[sentCount:] {
 				_, _ = m.treeSession.AppendFantasyMessage(msg)
@@ -1678,6 +1753,71 @@ func (m *Kit) FollowUp(ctx context.Context, text string) (string, error) {
 	return result.Response, nil
 }
 
+// InjectSteer sends a steering message into the currently active agent turn.
+// The message will be injected as a user message between steps (after the
+// current tool execution finishes, before the next LLM call). If no turn is
+// active the message is silently dropped — callers should check IsGenerating()
+// or use Prompt()/Steer() for idle-state messaging.
+//
+// InjectSteer is safe to call from any goroutine. Multiple calls queue
+// messages in order; all pending steer messages are drained and injected
+// together at the next step boundary.
+//
+// This is the preferred way to redirect an agent mid-turn without cancelling
+// in-progress tool execution.
+func (m *Kit) InjectSteer(message string) {
+	m.steerMu.Lock()
+	ch := m.steerCh
+	m.steerMu.Unlock()
+	if ch == nil {
+		return
+	}
+	select {
+	case ch <- message:
+	default:
+		// Channel full — extremely unlikely with buffer of 16, but don't block.
+	}
+}
+
+// IsGenerating returns true if an agent turn is currently in progress.
+// Use this to decide between InjectSteer (mid-turn) and Prompt (new turn).
+func (m *Kit) IsGenerating() bool {
+	m.steerMu.Lock()
+	defer m.steerMu.Unlock()
+	return m.steerCh != nil
+}
+
+// DrainSteer removes and returns all unconsumed steer messages. Called after
+// a turn completes so the app layer can process any steer messages that
+// arrived after the last PrepareStep fired (e.g. during a text-only response
+// with no tool calls, or after the agent finished its last step).
+func (m *Kit) DrainSteer() []string {
+	m.steerMu.Lock()
+	defer m.steerMu.Unlock()
+
+	// First check leftover messages saved when generate() returned.
+	if len(m.leftoverSteer) > 0 {
+		msgs := m.leftoverSteer
+		m.leftoverSteer = nil
+		return msgs
+	}
+
+	// If a turn is still active, drain from the live channel.
+	if m.steerCh != nil {
+		var msgs []string
+		for {
+			select {
+			case msg := <-m.steerCh:
+				msgs = append(msgs, msg)
+			default:
+				return msgs
+			}
+		}
+	}
+
+	return nil
+}
+
 // PromptOptions configures a single PromptWithOptions call.
 type PromptOptions struct {
 	// SystemMessage is prepended as a system message before the user prompt.

pkg/kit/kit_test.go

@@ -16,7 +16,10 @@ func TestNew(t *testing.T) {
 	ctx := context.Background()
 
 	// Test default initialization
-	host, err := kit.New(ctx, nil)
+	opts := &kit.Options{
+		Model: "anthropic/claude-sonnet-4-5-20250929",
+	}
+	host, err := kit.New(ctx, opts)
 	if err != nil {
 		t.Fatalf("Failed to create Kit with defaults: %v", err)
 	}

pkg/kit/sessions.go

@@ -34,6 +34,12 @@ func DeleteSession(path string) error {
 	return session.DeleteSession(path)
 }
 
+// OpenTreeSession opens an existing JSONL session file. This is a package-level
+// function (no Kit instance required) used by the CLI for session switching.
+func OpenTreeSession(path string) (*TreeManager, error) {
+	return session.OpenTreeSession(path)
+}
+
 // --- Instance methods on Kit ---
 
 // GetTreeSession returns the tree session manager, or nil if not configured.

skills/kit-sdk/SKILL.md

@@ -0,0 +1,772 @@
+---
+name: kit-sdk
+description: Guide for building Go applications with the Kit SDK. Use when the user asks to create a program, service, script, or application that uses Kit programmatically as a Go library — e.g. embedding LLM interactions, building agents, creating CLI tools powered by Kit, or integrating Kit into backend services. Do NOT use for Kit extensions (use kit-extensions skill instead).
+---
+
+# Kit SDK Development Guide
+
+The Kit SDK (`pkg/kit`) lets you embed Kit's full agent capabilities — LLM interactions, tool execution, session management, streaming, hooks — into any Go application. Unlike extensions (which are interpreted scripts running inside Kit's TUI), SDK programs are standalone compiled Go binaries.
+
+## Installation
+
+```bash
+go get github.com/mark3labs/kit
+```
+
+Import path (alias recommended):
+
+```go
+import kit "github.com/mark3labs/kit/pkg/kit"
+```
+
+## Quick Start
+
+```go
+package main
+
+import (
+    "context"
+    "fmt"
+    "log"
+
+    kit "github.com/mark3labs/kit/pkg/kit"
+)
+
+func main() {
+    ctx := context.Background()
+
+    host, err := kit.New(ctx, nil) // nil = load ~/.kit.yml defaults
+    if err != nil {
+        log.Fatal(err)
+    }
+    defer func() { _ = host.Close() }()
+
+    response, err := host.Prompt(ctx, "What is 2+2?")
+    if err != nil {
+        log.Fatal(err)
+    }
+    fmt.Println(response)
+}
+```
+
+## Core Lifecycle
+
+1. **Create**: `kit.New(ctx, opts)` — loads config, initializes MCP servers, creates LLM provider, sets up agent
+2. **Interact**: `host.Prompt(ctx, msg)` — send messages, agent uses tools as needed
+3. **Close**: `host.Close()` — cleans up MCP connections, model resources, session file handle
+
+Always defer `Close()`:
+
+```go
+defer func() { _ = host.Close() }()
+```
+
+---
+
+## Options Reference
+
+All fields are optional. Zero values use CLI defaults.
+
+```go
+host, err := kit.New(ctx, &kit.Options{
+    // Model
+    Model:        "anthropic/claude-sonnet-4-5-20250929", // "provider/model" format
+    SystemPrompt: "You are a helpful assistant",
+    ConfigFile:   "/path/to/config.yml",                  // default: ~/.kit.yml
+
+    // Behavior
+    MaxSteps:  10,   // 0 = unlimited tool-calling steps
+    Streaming: true, // stream LLM output (default from config)
+    Quiet:     true, // suppress debug output
+    Debug:     true, // enable debug logging
+
+    // Session
+    SessionDir:  "/path/to/project",  // base dir for session discovery (default: cwd)
+    SessionPath: "/path/to/session.jsonl", // open specific session file
+    Continue:    true,                // resume most recent session for SessionDir
+    NoSession:   true,                // ephemeral in-memory session, no disk persistence
+
+    // Tools
+    Tools:      []kit.Tool{kit.NewBashTool()}, // REPLACES entire default tool set
+    ExtraTools: []kit.Tool{myTool},            // ADDS alongside core/MCP/extension tools
+
+    // Skills
+    Skills:    []string{"/path/to/skill.md"}, // explicit skill files (empty = auto-discover)
+    SkillsDir: "/path/to/skills",             // override project-local skills dir
+
+    // Compaction
+    AutoCompact:       true,                        // auto-compact near context limit
+    CompactionOptions: &kit.CompactionOptions{...}, // nil = defaults
+})
+```
+
+**Critical distinction**: `Tools` replaces ALL default tools (core + MCP + extension). `ExtraTools` adds tools alongside the defaults. Use `Tools` to restrict the agent's capabilities; use `ExtraTools` to extend them.
+
+---
+
+## Prompt Methods
+
+### Simple prompt — string in, string out
+
+```go
+response, err := host.Prompt(ctx, "Explain this code")
+```
+
+### Full result with usage stats
+
+```go
+result, err := host.PromptResult(ctx, "Analyze this file")
+// result.Response     — assistant's text
+// result.StopReason   — "stop", "length", "tool-calls", "error", etc.
+// result.SessionID    — session UUID
+// result.TotalUsage   — aggregate tokens across all steps (*kit.FantasyUsage)
+// result.FinalUsage   — tokens from last API call only
+// result.Messages     — full updated conversation ([]kit.FantasyMessage)
+```
+
+### Multimodal with file attachments
+
+```go
+import "charm.land/fantasy"
+
+files := []fantasy.FilePart{{
+    Name:      "screenshot.png",
+    MediaType: "image/png",
+    Data:      imageBytes,
+}}
+result, err := host.PromptResultWithFiles(ctx, "What's in this image?", files)
+```
+
+### Per-call system message injection
+
+```go
+response, err := host.PromptWithOptions(ctx, "Review this PR", kit.PromptOptions{
+    SystemMessage: "Focus on security vulnerabilities only.",
+})
+```
+
+### System-level steering (no visible user message)
+
+```go
+response, err := host.Steer(ctx, "Switch to a more formal tone")
+```
+
+### Continue without new input
+
+```go
+response, err := host.FollowUp(ctx, "") // empty = "Continue."
+```
+
+### Multiple user messages in one turn
+
+```go
+result, err := host.PromptResultWithMessages(ctx, []string{
+    "Here is the code:",
+    "@file.go", // content from earlier
+    "Please review it.",
+})
+```
+
+### Legacy inline callbacks (deprecated — use event subscribers instead)
+
+```go
+response, err := host.PromptWithCallbacks(ctx, "List files",
+    func(name, args string) { fmt.Printf("Tool: %s\n", name) },
+    func(name, args, result string, isError bool) { /* tool result */ },
+    func(chunk string) { fmt.Print(chunk) }, // streaming
+)
+```
+
+---
+
+## Event System
+
+Events are read-only observations of the agent lifecycle. Register before calling Prompt.
+
+### Typed convenience subscribers
+
+```go
+// Each returns an unsubscribe function.
+unsub := host.OnToolCall(func(e kit.ToolCallEvent) {
+    // e.ToolCallID, e.ToolName, e.ToolKind, e.ToolArgs, e.ParsedArgs
+})
+defer unsub()
+
+host.OnToolResult(func(e kit.ToolResultEvent) {
+    // e.ToolCallID, e.ToolName, e.ToolKind, e.ToolArgs, e.ParsedArgs
+    // e.Result, e.IsError, e.Metadata (*ToolResultMetadata)
+})
+
+host.OnToolOutput(func(e kit.ToolOutputEvent) {
+    // e.ToolCallID, e.ToolName, e.Chunk, e.IsStderr
+    // Streaming bash output chunks
+})
+
+host.OnStreaming(func(e kit.MessageUpdateEvent) {
+    fmt.Print(e.Chunk) // real-time text streaming
+})
+
+host.OnResponse(func(e kit.ResponseEvent) {
+    // e.Content — final response text
+})
+
+host.OnTurnStart(func(e kit.TurnStartEvent) {
+    // e.Prompt
+})
+
+host.OnTurnEnd(func(e kit.TurnEndEvent) {
+    // e.Response, e.Error, e.StopReason
+})
+```
+
+### Generic subscriber (receives all events)
+
+```go
+unsub := host.Subscribe(func(e kit.Event) {
+    switch ev := e.(type) {
+    case kit.ToolCallEvent:
+        // ...
+    case kit.MessageUpdateEvent:
+        // ...
+    case kit.CompactionEvent:
+        // ev.Summary, ev.OriginalTokens, ev.CompactedTokens
+    }
+})
+```
+
+### All event types
+
+| Event Type | Struct | Key Fields |
+|------------|--------|------------|
+| `turn_start` | `TurnStartEvent` | `Prompt` |
+| `turn_end` | `TurnEndEvent` | `Response`, `Error`, `StopReason` |
+| `message_start` | `MessageStartEvent` | *(none)* |
+| `message_update` | `MessageUpdateEvent` | `Chunk` |
+| `message_end` | `MessageEndEvent` | `Content` |
+| `tool_call` | `ToolCallEvent` | `ToolCallID`, `ToolName`, `ToolKind`, `ToolArgs`, `ParsedArgs` |
+| `tool_execution_start` | `ToolExecutionStartEvent` | `ToolCallID`, `ToolName`, `ToolKind`, `ToolArgs` |
+| `tool_execution_end` | `ToolExecutionEndEvent` | `ToolCallID`, `ToolName`, `ToolKind` |
+| `tool_result` | `ToolResultEvent` | `ToolCallID`, `ToolName`, `ToolKind`, `ToolArgs`, `ParsedArgs`, `Result`, `IsError`, `Metadata` |
+| `tool_call_content` | `ToolCallContentEvent` | `Content` |
+| `tool_output` | `ToolOutputEvent` | `ToolCallID`, `ToolName`, `Chunk`, `IsStderr` |
+| `response` | `ResponseEvent` | `Content` |
+| `compaction` | `CompactionEvent` | `Summary`, `OriginalTokens`, `CompactedTokens`, `MessagesRemoved`, `ReadFiles`, `ModifiedFiles` |
+| `reasoning_delta` | `ReasoningDeltaEvent` | `Delta` |
+
+### Tool kind constants
+
+Tools are classified by kind for UI rendering:
+
+- `ToolKindExecute` = `"execute"` — bash
+- `ToolKindEdit` = `"edit"` — edit, write
+- `ToolKindRead` = `"read"` — read, ls
+- `ToolKindSearch` = `"search"` — grep, find
+- `ToolKindSubagent` = `"agent"` — spawn_subagent
+
+---
+
+## Hook System (Interceptors)
+
+Hooks can **modify or cancel** operations. Events are read-only; hooks are read-write.
+
+### BeforeToolCall — block tool execution
+
+```go
+unsub := host.OnBeforeToolCall(kit.HookPriorityNormal, func(h kit.BeforeToolCallHook) *kit.BeforeToolCallResult {
+    // h.ToolCallID, h.ToolName, h.ToolArgs
+    if h.ToolName == "bash" {
+        return &kit.BeforeToolCallResult{Block: true, Reason: "bash disabled"}
+    }
+    return nil // allow
+})
+```
+
+### AfterToolResult — modify tool output
+
+```go
+host.OnAfterToolResult(kit.HookPriorityNormal, func(h kit.AfterToolResultHook) *kit.AfterToolResultResult {
+    // h.ToolCallID, h.ToolName, h.ToolArgs, h.Result, h.IsError
+    if h.ToolName == "read" {
+        filtered := redactSecrets(h.Result)
+        return &kit.AfterToolResultResult{Result: &filtered}
+    }
+    return nil
+})
+```
+
+### BeforeTurn — modify prompt, inject messages
+
+```go
+host.OnBeforeTurn(kit.HookPriorityNormal, func(h kit.BeforeTurnHook) *kit.BeforeTurnResult {
+    // h.Prompt
+    newPrompt := h.Prompt + "\nAlways respond in JSON."
+    return &kit.BeforeTurnResult{Prompt: &newPrompt}
+    // Also available: SystemPrompt *string, InjectText *string
+})
+```
+
+### AfterTurn — observation only
+
+```go
+host.OnAfterTurn(kit.HookPriorityNormal, func(h kit.AfterTurnHook) {
+    // h.Response, h.Error
+    log.Printf("Turn completed: %d chars", len(h.Response))
+})
+```
+
+### ContextPrepare — filter/inject context window
+
+```go
+host.OnContextPrepare(kit.HookPriorityNormal, func(h kit.ContextPrepareHook) *kit.ContextPrepareResult {
+    // h.Messages — []fantasy.Message (the full context being sent to the LLM)
+    // Return nil to pass through, or replace entire context:
+    return &kit.ContextPrepareResult{Messages: filteredMessages}
+})
+```
+
+### BeforeCompact — cancel or customize compaction
+
+```go
+host.OnBeforeCompact(kit.HookPriorityNormal, func(h kit.BeforeCompactHook) *kit.BeforeCompactResult {
+    // h.EstimatedTokens, h.ContextLimit, h.UsagePercent, h.MessageCount, h.IsAutomatic
+    if h.IsAutomatic && h.UsagePercent < 0.9 {
+        return &kit.BeforeCompactResult{Cancel: true, Reason: "not yet"}
+    }
+    return nil
+})
+```
+
+### Hook priorities
+
+```go
+kit.HookPriorityHigh   = 0   // runs first
+kit.HookPriorityNormal = 50  // default
+kit.HookPriorityLow    = 100 // runs last
+```
+
+Lower values run first. Within the same priority, registration order applies. First non-nil result wins.
+
+---
+
+## Tools
+
+### Built-in tool constructors
+
+```go
+kit.NewReadTool(opts...)  // file reading
+kit.NewWriteTool(opts...) // file writing
+kit.NewEditTool(opts...)  // surgical text editing
+kit.NewBashTool(opts...)  // bash command execution
+kit.NewGrepTool(opts...) // content search (uses ripgrep when available)
+kit.NewFindTool(opts...) // file search (uses fd when available)
+kit.NewLsTool(opts...)   // directory listing
+```
+
+### Tool bundles
+
+```go
+kit.AllTools(opts...)       // all 7 core tools
+kit.CodingTools(opts...)    // bash, read, write, edit
+kit.ReadOnlyTools(opts...)  // read, grep, find, ls
+kit.SubagentTools(opts...)  // all except spawn_subagent (prevents recursion)
+```
+
+### Tool options
+
+```go
+kit.WithWorkDir("/path/to/dir") // override working directory for file-based tools
+```
+
+### Using tools in Options
+
+```go
+// Restricted: agent can ONLY run bash
+host, _ := kit.New(ctx, &kit.Options{
+    Tools: []kit.Tool{kit.NewBashTool()},
+})
+
+// Extended: all defaults PLUS a custom tool
+host, _ := kit.New(ctx, &kit.Options{
+    ExtraTools: []kit.Tool{myCustomTool},
+})
+```
+
+### Querying tools at runtime
+
+```go
+names := host.GetToolNames()       // []string of all tool names
+tools := host.GetTools()           // []kit.Tool (full tool objects)
+mcpCount := host.GetMCPToolCount() // tools from MCP servers
+extCount := host.GetExtensionToolCount() // tools from extensions
+```
+
+---
+
+## Session Management
+
+Sessions automatically persist as JSONL tree files. No explicit save needed.
+
+### Session modes (via Options)
+
+| Mode | Options | Behavior |
+|------|---------|----------|
+| Default | `{}` | New session file for cwd |
+| Specific file | `{SessionPath: "path.jsonl"}` | Open existing session |
+| Continue | `{Continue: true}` | Resume most recent session for cwd |
+| Ephemeral | `{NoSession: true}` | In-memory only, no disk persistence |
+| Custom dir | `{SessionDir: "/path"}` | Base directory for session discovery |
+
+### Instance methods
+
+```go
+host.GetSessionPath() // file path of active session
+host.GetSessionID()   // UUID of active session
+host.ClearSession()   // reset to fresh branch (doesn't delete file)
+host.Branch("entry-id") // branch from a specific entry
+host.SetSessionName("my session") // set display name
+
+// Get conversation messages
+msgs := host.GetSessionMessages()       // []extensions.SessionMessage (flattened text)
+msgs := host.GetStructuredMessages()     // []kit.StructuredMessage (typed content parts)
+```
+
+### Package-level session operations (no Kit instance needed)
+
+```go
+sessions, _ := kit.ListSessions("/path/to/project") // sessions for a directory
+sessions, _ := kit.ListAllSessions()                  // all sessions everywhere
+kit.DeleteSession("/path/to/session.jsonl")
+tm, _ := kit.OpenTreeSession("/path/to/session.jsonl") // open for direct access
+```
+
+---
+
+## Model Management
+
+### At creation time
+
+```go
+host, _ := kit.New(ctx, &kit.Options{
+    Model: "openai/gpt-4o",
+})
+```
+
+### At runtime
+
+```go
+err := host.SetModel(ctx, "anthropic/claude-sonnet-4-5-20250929")
+modelStr := host.GetModelString()   // "provider/model"
+info := host.GetModelInfo()          // *kit.ModelInfo (capabilities, limits, pricing) or nil
+isReasoning := host.IsReasoningModel()
+level := host.GetThinkingLevel()
+err = host.SetThinkingLevel(ctx, "medium") // recreates agent with new thinking budget
+```
+
+### Model registry
+
+```go
+models := host.GetAvailableModels()      // []extensions.ModelInfoEntry
+providers := kit.GetSupportedProviders() // []string
+providers := kit.GetFantasyProviders()   // providers usable with fantasy
+models, _ := kit.GetModelsForProvider("anthropic") // map[string]kit.ModelInfo
+info := kit.LookupModel("anthropic", "claude-sonnet-4-5-20250929") // *kit.ModelInfo
+info := kit.GetProviderInfo("openai")    // *kit.ProviderInfo (env vars, API URL)
+err := kit.ValidateEnvironment("anthropic", "") // check API keys
+suggestions := kit.SuggestModels("anthropic", "claudee") // fuzzy match
+kit.RefreshModelRegistry() // reload model database
+```
+
+### Model string format
+
+Always `"provider/model"`: `"anthropic/claude-sonnet-4-5-20250929"`, `"openai/gpt-4o"`, `"ollama/qwen3:8b"`.
+
+```go
+provider, modelID, err := kit.ParseModelString("anthropic/claude-sonnet-4-5-20250929")
+```
+
+---
+
+## Context & Compaction
+
+```go
+tokens := host.EstimateContextTokens()  // heuristic token count
+shouldCompact := host.ShouldCompact()    // true if near context limit
+
+stats := host.GetContextStats()
+// stats.EstimatedTokens — uses API-reported count when available (more accurate)
+// stats.ContextLimit    — model's context window size
+// stats.UsagePercent    — fraction used (0.0–1.0)
+// stats.MessageCount    — number of messages
+
+// Manual compaction
+result, err := host.Compact(ctx, nil, "") // nil opts = defaults, "" = default prompt
+// result.Summary, result.OriginalTokens, result.CompactedTokens, result.MessagesRemoved
+
+// Auto-compaction via Options
+host, _ := kit.New(ctx, &kit.Options{
+    AutoCompact: true,
+    CompactionOptions: &kit.CompactionOptions{
+        ReserveTokens:   16384,
+        KeepRecentTokens: 4096,
+        ContextWindow:   200000,
+    },
+})
+```
+
+---
+
+## In-Process Subagents
+
+Spawn child Kit instances without subprocess overhead:
+
+```go
+result, err := host.Subagent(ctx, kit.SubagentConfig{
+    Prompt:       "Analyze the test files and summarize coverage",
+    Model:        "anthropic/claude-haiku-3-5-20241022", // empty = parent's model
+    SystemPrompt: "You are a test analysis expert.",
+    Tools:        nil,           // nil = SubagentTools() (all except spawn_subagent)
+    NoSession:    true,          // ephemeral
+    Timeout:      2 * time.Minute, // 0 = 5 minute default
+    OnEvent: func(e kit.Event) {
+        // Real-time events from the child agent
+        if chunk, ok := e.(kit.MessageUpdateEvent); ok {
+            fmt.Print(chunk.Chunk)
+        }
+    },
+})
+// result.Response, result.Error, result.SessionID, result.StopReason
+// result.Usage (*kit.FantasyUsage), result.Elapsed (time.Duration)
+```
+
+### Subscribing to subagent events from parent
+
+```go
+host.OnToolCall(func(e kit.ToolCallEvent) {
+    if e.ToolName == "spawn_subagent" {
+        host.SubscribeSubagent(e.ToolCallID, func(child kit.Event) {
+            // Real-time events scoped to this subagent
+        })
+    }
+})
+```
+
+---
+
+## Authentication
+
+```go
+cm, _ := kit.NewCredentialManager()
+hasKey := kit.HasAnthropicCredentials()
+apiKey := kit.GetAnthropicAPIKey() // stored creds → ANTHROPIC_API_KEY env var
+```
+
+---
+
+## Skills
+
+```go
+// Load a single skill file
+skill, _ := kit.LoadSkill("/path/to/SKILL.md")
+// skill.Name, skill.Description, skill.Content, skill.Path
+
+// Load from directory
+skills, _ := kit.LoadSkillsFromDir("/path/to/skills")
+
+// Auto-discover (global + project-local)
+skills, _ := kit.LoadSkills("/path/to/project")
+
+// Prompt building with skills
+pb := kit.NewPromptBuilder("You are an assistant")
+pb.WithSkills(skills)
+pb.WithSection("", "Extra context here")
+systemPrompt := pb.Build()
+```
+
+---
+
+## Re-exported Types
+
+The SDK re-exports internal types so you don't need direct internal imports:
+
+```go
+// Message types
+kit.Message, kit.MessageRole, kit.ContentPart
+kit.TextContent, kit.ReasoningContent, kit.ToolCall, kit.ToolResult, kit.Finish
+kit.RoleUser, kit.RoleAssistant, kit.RoleTool, kit.RoleSystem
+
+// Session types
+kit.SessionInfo, kit.TreeManager, kit.SessionHeader, kit.MessageEntry
+
+// Config types
+kit.Config, kit.MCPServerConfig
+
+// Provider types
+kit.ProviderConfig, kit.ProviderResult, kit.ModelInfo, kit.ModelCost, kit.ModelLimit
+
+// Fantasy types (from charm.land/fantasy)
+kit.FantasyMessage, kit.FantasyUsage, kit.FantasyResponse
+
+// Compaction types
+kit.CompactionResult, kit.CompactionOptions
+
+// Conversion helpers
+msgs := kit.ConvertToFantasyMessages(&msg)   // SDK message → fantasy messages
+msg := kit.ConvertFromFantasyMessage(fMsg)    // fantasy message → SDK message
+```
+
+---
+
+## Common Patterns
+
+### Pattern: Scripting / CLI pipe
+
+Minimal program for automation — stdout-only output:
+
+```go
+host, _ := kit.New(ctx, &kit.Options{Quiet: true})
+defer func() { _ = host.Close() }()
+
+response, _ := host.Prompt(ctx, os.Args[1])
+fmt.Println(response)
+```
+
+### Pattern: Long-running autonomous agent
+
+Daemon that performs repeated independent tasks:
+
+```go
+host, _ := kit.New(ctx, &kit.Options{
+    SystemPrompt: taskPrompt,
+    Tools:        []kit.Tool{kit.NewBashTool()},
+    NoSession:    true,
+    Quiet:        true,
+})
+defer func() { _ = host.Close() }()
+
+ticker := time.NewTicker(30 * time.Minute)
+for {
+    select {
+    case <-ticker.C:
+        host.ClearSession() // fresh context each iteration
+        host.Prompt(ctx, "Perform the monitoring task")
+    case <-ctx.Done():
+        return
+    }
+}
+```
+
+### Pattern: Streaming output to terminal
+
+```go
+host.OnStreaming(func(e kit.MessageUpdateEvent) {
+    fmt.Print(e.Chunk)
+})
+response, _ := host.Prompt(ctx, "Write a poem")
+```
+
+### Pattern: Multi-turn conversation with memory
+
+```go
+host.Prompt(ctx, "My name is Alice")
+response, _ := host.Prompt(ctx, "What's my name?")
+// Session automatically maintains context across calls
+fmt.Printf("Session: %s\n", host.GetSessionPath())
+```
+
+### Pattern: Tool execution monitoring
+
+```go
+host.OnToolCall(func(e kit.ToolCallEvent) {
+    fmt.Printf("[%s] %s(%s)\n", e.ToolKind, e.ToolName, e.ToolArgs)
+})
+host.OnToolResult(func(e kit.ToolResultEvent) {
+    status := "✓"
+    if e.IsError { status = "✗" }
+    fmt.Printf("[%s] %s %s\n", e.ToolKind, status, e.ToolName)
+})
+```
+
+### Pattern: Guard rails with hooks
+
+```go
+// Block dangerous commands
+host.OnBeforeToolCall(kit.HookPriorityHigh, func(h kit.BeforeToolCallHook) *kit.BeforeToolCallResult {
+    if h.ToolName == "bash" && strings.Contains(h.ToolArgs, "rm -rf") {
+        return &kit.BeforeToolCallResult{Block: true, Reason: "dangerous command"}
+    }
+    return nil
+})
+
+// Inject context before every turn
+host.OnBeforeTurn(kit.HookPriorityNormal, func(h kit.BeforeTurnHook) *kit.BeforeTurnResult {
+    context := "Current user: admin\nEnvironment: production"
+    return &kit.BeforeTurnResult{InjectText: &context}
+})
+```
+
+### Pattern: Parallel subagents
+
+```go
+var wg sync.WaitGroup
+results := make([]*kit.SubagentResult, 3)
+
+tasks := []string{"Analyze auth module", "Analyze database layer", "Analyze API routes"}
+for i, task := range tasks {
+    wg.Add(1)
+    go func(idx int, t string) {
+        defer wg.Done()
+        results[idx], _ = host.Subagent(ctx, kit.SubagentConfig{
+            Prompt:    t,
+            NoSession: true,
+            Timeout:   3 * time.Minute,
+        })
+    }(i, task)
+}
+wg.Wait()
+```
+
+### Pattern: Read-only analysis agent
+
+```go
+host, _ := kit.New(ctx, &kit.Options{
+    SystemPrompt: "You are a code reviewer. Only read and analyze, never modify files.",
+    Tools:        kit.ReadOnlyTools(),
+})
+```
+
+---
+
+## Configuration
+
+The SDK loads config identically to the CLI:
+
+1. Explicit `ConfigFile` in Options (highest priority)
+2. `.kit.yml` in current directory
+3. `~/.kit.yml` in home directory
+4. Environment variables with `KIT_` prefix (`KIT_MODEL`, etc.)
+5. Provider-specific env vars (`ANTHROPIC_API_KEY`, `OPENAI_API_KEY`, etc.)
+
+Config files support `${ENV_VAR}` expansion.
+
+```go
+// Initialize config manually (usually not needed — kit.New handles this)
+kit.InitConfig("/path/to/config.yml", false)
+kit.LoadConfigWithEnvSubstitution("/path/to/config.yml")
+```
+
+---
+
+## Key Files for Reference
+
+- [`pkg/kit/kit.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/kit.go) — Kit struct, New(), Prompt methods, Subagent, Close
+- [`pkg/kit/types.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/types.go) — Re-exported types from internal packages
+- [`pkg/kit/tools.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/tools.go) — Tool constructors and bundles
+- [`pkg/kit/events.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/events.go) — Event types, EventBus, typed subscribers
+- [`pkg/kit/hooks.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/hooks.go) — Hook system (BeforeToolCall, AfterToolResult, etc.)
+- [`pkg/kit/sessions.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/sessions.go) — Session management
+- [`pkg/kit/compaction.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/compaction.go) — Context compaction
+- [`pkg/kit/models.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/models.go) — Model registry lookups
+- [`pkg/kit/config.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/config.go) — Config initialization and defaults
+- [`pkg/kit/skills.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/skills.go) — Skills loading and prompt building
+- [`pkg/kit/auth.go`](https://github.com/mark3labs/kit/blob/main/pkg/kit/auth.go) — Credential management
+- [`examples/sdk/`](https://github.com/mark3labs/kit/tree/main/examples/sdk) — Working example programs

www/pages/advanced/subagents.md

@@ -59,6 +59,79 @@ result := ctx.SpawnSubagent(ext.SubagentConfig{
 })
 ```
 
+### Monitoring subagents from extensions
+
+When the LLM (not the extension itself) spawns a subagent using the `spawn_subagent` tool, extensions can monitor its activity in real-time using three lifecycle event handlers:
+
+```go
+// Track active subagents and display their output
+var subagentWidgets map[string]*SubagentWidget
+
+func Init(api ext.API) {
+    // Subagent started by the main agent
+    api.OnSubagentStart(func(e ext.SubagentStartEvent, ctx ext.Context) {
+        // e.ToolCallID — unique ID for this subagent invocation
+        // e.Task — the task/prompt sent to the subagent
+        widget := NewWidget(e.ToolCallID, e.Task)
+        subagentWidgets[e.ToolCallID] = widget
+        ctx.SetWidget(widget.Config())
+    })
+
+    // Real-time streaming from subagent
+    api.OnSubagentChunk(func(e ext.SubagentChunkEvent, ctx ext.Context) {
+        // e.ToolCallID — matches the start event
+        // e.ChunkType — "text", "tool_call", "tool_execution_start", "tool_result"
+        // e.Content — text content
+        // e.ToolName — tool name (for tool chunks)
+        // e.IsError — true if tool result failed
+        widget := subagentWidgets[e.ToolCallID]
+        if widget != nil {
+            widget.AddOutput(e)
+            ctx.SetWidget(widget.Config())
+        }
+    })
+
+    // Subagent completed
+    api.OnSubagentEnd(func(e ext.SubagentEndEvent, ctx ext.Context) {
+        // e.Response — final response from subagent
+        // e.ErrorMsg — error message if subagent failed
+        widget := subagentWidgets[e.ToolCallID]
+        if widget != nil {
+            widget.MarkComplete(e.Response, e.ErrorMsg)
+            ctx.SetWidget(widget.Config())
+            delete(subagentWidgets, e.ToolCallID)
+        }
+    })
+}
+```
+
+**Event structs:**
+
+```go
+type SubagentStartEvent struct {
+    ToolCallID string  // Unique ID for this subagent invocation
+    Task       string  // The task/prompt sent to subagent
+}
+
+type SubagentChunkEvent struct {
+    ToolCallID string  // Matches SubagentStartEvent.ToolCallID
+    Task       string  // Task description
+    ChunkType  string  // "text", "tool_call", "tool_execution_start", "tool_result"
+    Content    string  // For text chunks
+    ToolName   string  // For tool-related chunks
+    IsError    bool    // For tool_result chunks
+}
+
+type SubagentEndEvent struct {
+    ToolCallID string  // Matches start event
+    Task       string  // Task description
+    Response   string  // Final response from subagent
+    ErrorMsg   string  // Error message if failed
+}
+```
+
+This enables building monitoring widgets that display real-time activity from all subagents spawned by the main agent.
+
 ## Go SDK subagents
 
 The SDK provides in-process subagent spawning:
@@ -71,3 +144,28 @@ result, err := host.Subagent(ctx, kit.SubagentConfig{
     Timeout:      5 * time.Minute,
 })
 ```
+
+### Real-time subagent events
+
+Use `SubscribeSubagent` to receive real-time events from LLM-initiated subagents (i.e., when the model uses the `spawn_subagent` tool). Register inside an `OnToolCall` handler using the tool call ID:
+
+```go
+host.OnToolCall(func(e kit.ToolCallEvent) {
+    if e.ToolName == "spawn_subagent" {
+        host.SubscribeSubagent(e.ToolCallID, func(event kit.Event) {
+            switch ev := event.(type) {
+            case kit.MessageUpdateEvent:
+                fmt.Print(ev.Chunk) // streaming text from child
+            case kit.ToolCallEvent:
+                fmt.Printf("Child calling: %s\n", ev.ToolName)
+            case kit.ToolResultEvent:
+                fmt.Printf("Child result: %s\n", ev.ToolName)
+            }
+        })
+    }
+})
+```
+
+The listener receives the same event types as `Subscribe()` (`ToolCallEvent`, `MessageUpdateEvent`, `ReasoningDeltaEvent`, etc.) but scoped to the child agent's activity. Listeners are cleaned up automatically when the subagent completes.
+
+If no listeners are registered for a tool call, no event dispatching overhead is incurred.

www/pages/cli/commands.md

@@ -74,11 +74,80 @@ These commands are available inside the Kit TUI during an interactive session:
 | `/reset-usage` | Reset usage statistics |
 | `/tree` | Navigate session tree |
 | `/fork` | Branch from an earlier message |
-| `/new` | Start a new session |
-| `/name` | Set session display name |
+| `/new` | Start a new session (creates new session file) |
+| `/name [name]` | Set or show session display name |
+| `/resume` | Open session picker to switch sessions (alias: `/r`) |
 | `/session` | Show session info |
+| `/export [path]` | Export session as JSONL (default: auto-generated path) |
+| `/import <path>` | Import a session from a JSONL file |
+| `/share` | Upload session to GitHub Gist and get a shareable viewer URL |
 | `/quit` | Exit Kit |
 
+### Prompt history
+
+Use **↑** and **↓** arrow keys to navigate through previously submitted prompts. Kit keeps the last 100 entries. Consecutive duplicates are skipped.
+
+### Cancelling operations
+
+Press **ESC twice** to cancel the current operation:
+- During a tool call: rolls back the entire turn to maintain API message pairing
+- During streaming: stops the response generation
+
+This ensures that `tool_use` and `tool_result` messages are always sent to the API as matched pairs, avoiding errors from orphaned tool calls.
+
+### Mid-turn steering
+
+Press **Ctrl+S** during streaming to inject a system-level instruction mid-turn. This allows you to steer the conversation direction without waiting for the model to finish:
+
+- Works during streaming output
+- Sends a steering instruction as a system message
+- Model continues from the interruption point with the new guidance
+
+Example: While the model is writing code, press Ctrl+S and type "Use async/await instead" to change the implementation approach.
+
+## Prompt templates
+
+### Creating templates
+
+Templates use YAML frontmatter for metadata and support argument placeholders:
+
+```markdown
+---
+description: Review code for issues
+---
+Review the following code for bugs and security issues.
+Focus on $1 specifically.
+```
+
+Save to `~/.kit/prompts/review.md` or `.kit/prompts/review.md`.
+
+### Using templates
+
+Templates appear as slash commands:
+
+```
+/review error handling
+```
+
+### Argument placeholders
+
+| Placeholder | Description |
+|-------------|-------------|
+| `$1`, `$2`, etc. | Individual arguments by position |
+| `$@`, `$ARGUMENTS` | All arguments joined with spaces |
+| `${@:N}` | Arguments from position N onwards |
+| `${@:N:L}` | L arguments starting at position N |
+
+### CLI flags
+
+```bash
+# Load a specific template by name
+kit --prompt-template review
+
+# Disable template loading
+kit --no-prompt-templates
+```
+
 ## ACP server
 
 Run Kit as an [ACP (Agent Client Protocol)](https://agentclientprotocol.com) agent server. ACP-compatible clients communicate with Kit over JSON-RPC 2.0 on stdin/stdout.

www/pages/cli/flags.md

@@ -45,6 +45,8 @@ These flags control Kit's behavior. When a prompt is passed as a positional argu
 |------|-------|---------|-------------|
 | `--extension` | `-e` | — | Load additional extension file(s) (repeatable) |
 | `--no-extensions` | — | `false` | Disable all extensions |
+| `--prompt-template` | — | — | Load a specific prompt template by name |
+| `--no-prompt-templates` | — | `false` | Disable prompt template loading |
 
 ## Generation parameters
 

www/pages/configuration.md

@@ -43,6 +43,8 @@ stream: true
 | `tls-skip-verify` | bool | `false` | Skip TLS certificate verification |
 | `stop-sequences` | list | — | Custom stop sequences |
 | `theme` | object or string | — | UI theme ([inline overrides or file path](/themes)) |
+| `prompt-templates` | bool | `true` | Enable prompt template loading |
+| `prompt-template` | string | — | Specific template to load by name |
 
 ## Environment variables
 
@@ -94,9 +96,45 @@ mcpServers:
 
 A legacy format with `transport`, `args`, `env`, and `headers` fields is also supported.
 
-## Theme configuration
+## Custom models
 
-Set theme colors inline or reference an external file:
+Define custom models in your `.kit.yml` for use with the `custom` provider. This is useful for self-hosted models or API endpoints not in the built-in database:
+
+```yaml
+customModels:
+  my-model:
+    name: "My Custom Model"
+    reasoning: true
+    temperature: true
+    cost:
+      input: 0.002
+      output: 0.004
+    limit:
+      context: 128000
+      output: 32000
+```
+
+### Custom model fields
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `name` | string | Yes | Display name for the model |
+| `reasoning` | bool | No | Whether the model supports reasoning/thinking |
+| `temperature` | bool | No | Whether the model supports temperature adjustment |
+| `cost.input` | float | No | Cost per 1K input tokens |
+| `cost.output` | float | No | Cost per 1K output tokens |
+| `limit.context` | int | Yes | Maximum context window in tokens |
+| `limit.output` | int | No | Maximum output tokens |
+
+Use with a custom provider URL:
+
+```bash
+kit --provider-url "http://localhost:8080/v1" --model custom/my-model "Hello"
+```
+
+When `--provider-url` is specified without `--model`, Kit defaults to `custom/custom` which has zero cost tracking and a 262K context window.
+
+## Theme configuration
 
 ```yaml
 # Inline partial overrides (unspecified fields inherit from default)
@@ -114,3 +152,17 @@ theme: "./themes/my-custom-theme.yml"
 ```
 
 See [Themes](/themes) for the full theme file format, built-in themes, and the extension theme API.
+
+## Preferences persistence
+
+Kit automatically saves your UI preferences across sessions to `~/.config/kit/preferences.yml`:
+
+- **Theme** — Set via `/theme <name>` or `ctx.SetTheme()`
+- **Model** — Set via `/model <name>` or the model selector
+- **Thinking level** — Set via `/thinking <level>` or Shift+Tab cycling
+
+These preferences are restored on next launch. Precedence (highest to lowest):
+1. CLI flags (`--model`, `--thinking-level`)
+2. Config file (`model:`, `thinking-level:`)
+3. Saved preferences (`~/.config/kit/preferences.yml`)
+4. Default values

www/pages/extensions/capabilities.md

@@ -7,7 +7,7 @@ description: All extension capabilities — lifecycle events, tools, commands, w
 
 ## Lifecycle events
 
-Extensions can hook into 18 lifecycle events:
+Extensions can hook into 23 lifecycle events:
 
 | Event | Description |
 |-------|-------------|
@@ -18,6 +18,7 @@ Extensions can hook into 18 lifecycle events:
 | `OnAgentEnd` | Agent loop completed |
 | `OnToolCall` | Tool call requested by the model |
 | `OnToolExecutionStart` | Tool execution beginning |
+| `OnToolOutput` | Streaming tool output chunk (for long-running tools) |
 | `OnToolExecutionEnd` | Tool execution completed |
 | `OnToolResult` | Tool result returned |
 | `OnInput` | User input received |
@@ -29,6 +30,10 @@ Extensions can hook into 18 lifecycle events:
 | `OnBeforeFork` | Before forking a conversation branch |
 | `OnBeforeSessionSwitch` | Before switching sessions |
 | `OnBeforeCompact` | Before conversation compaction |
+| `OnCustomEvent` | Custom inter-extension event received |
+| `OnSubagentStart` | Subagent spawned by the main agent |
+| `OnSubagentChunk` | Real-time output from subagent (text, tool calls, results) |
+| `OnSubagentEnd` | Subagent completed with final response/error |
 
 ### Example
 
@@ -232,6 +237,54 @@ result := ctx.SpawnSubagent(ext.SubagentConfig{
 })
 ```
 
+### Monitoring subagents spawned by the main agent
+
+When the LLM uses the built-in `spawn_subagent` tool, extensions can monitor the subagent's activity in real-time using three lifecycle events:
+
+```go
+// Subagent started
+api.OnSubagentStart(func(e ext.SubagentStartEvent, ctx ext.Context) {
+    // e.ToolCallID — unique ID for this subagent invocation
+    // e.Task — the task/prompt sent to the subagent
+    ctx.PrintInfo(fmt.Sprintf("Subagent started: %s", e.Task))
+})
+
+// Real-time streaming output from subagent
+api.OnSubagentChunk(func(e ext.SubagentChunkEvent, ctx ext.Context) {
+    // e.ToolCallID — matches the start event
+    // e.Task — task description
+    // e.ChunkType — "text", "tool_call", "tool_execution_start", "tool_result"
+    // e.Content — text content (for text chunks)
+    // e.ToolName — tool name (for tool-related chunks)
+    // e.IsError — true if tool result is an error
+    switch e.ChunkType {
+    case "text":
+        // Streaming text output
+    case "tool_call":
+        // Subagent is calling a tool
+    case "tool_execution_start":
+        // Tool execution started
+    case "tool_result":
+        // Tool execution completed (check e.IsError)
+    }
+})
+
+// Subagent completed
+api.OnSubagentEnd(func(e ext.SubagentEndEvent, ctx ext.Context) {
+    // e.ToolCallID — matches start event
+    // e.Task — task description
+    // e.Response — final response from subagent
+    // e.ErrorMsg — error message if subagent failed
+    if e.ErrorMsg != "" {
+        ctx.PrintError(fmt.Sprintf("Subagent failed: %s", e.ErrorMsg))
+    } else {
+        ctx.PrintInfo(fmt.Sprintf("Subagent completed: %s", e.Response))
+    }
+})
+```
+
+This enables building widgets that display real-time subagent activity.
+
 ## LLM completion
 
 Make direct model calls without going through the agent loop:

www/pages/extensions/examples.md

@@ -51,6 +51,12 @@ Kit ships with a rich set of example extensions in the `examples/extensions/` di
 | [`summarize.go`](https://github.com/mark3labs/kit/blob/master/examples/extensions/summarize.go) | Conversation summarization |
 | [`lsp-diagnostics.go`](https://github.com/mark3labs/kit/blob/master/examples/extensions/lsp-diagnostics.go) | LSP diagnostic integration |
 
+## Themes
+
+| Extension | Description |
+|-----------|-------------|
+| [`neon-theme.go`](https://github.com/mark3labs/kit/blob/master/examples/extensions/neon-theme.go) | Custom theme registration and switching |
+
 ## Multi-agent
 
 | Extension | Description |
@@ -74,3 +80,7 @@ Kit ships with a rich set of example extensions in the `examples/extensions/` di
 | [`kit-kit-agents/`](https://github.com/mark3labs/kit/tree/master/examples/extensions/kit-kit-agents) | Multi-agent orchestration example |
 | [`kit-telegram/`](https://github.com/mark3labs/kit/tree/master/examples/extensions/kit-telegram) | Telegram bot integration |
 | [`status-tools/`](https://github.com/mark3labs/kit/tree/master/examples/extensions/status-tools) | Status bar tool examples |
+
+## Project-local example
+
+The Kit repository also includes a project-local extension at `.kit/extensions/go-edit-lint.go` that demonstrates running `gopls` and `golangci-lint` on Go file edits. This serves as an example of how to create extensions specific to a project by placing them in the `.kit/extensions/` directory.

www/pages/providers.md

@@ -20,6 +20,7 @@ Kit supports a wide range of LLM providers through a unified `provider/model` st
 | **Google Vertex** | `google-vertex-anthropic/` | Claude on Vertex AI |
 | **OpenRouter** | `openrouter/` | Multi-provider router |
 | **Vercel AI** | `vercel/` | Vercel AI SDK models |
+| **Custom** | `custom/` | Any OpenAI-compatible endpoint |
 | **Auto-routed** | any | Any provider from the models.dev database |
 
 ## Model string format
@@ -132,6 +133,16 @@ For self-hosted or proxy endpoints:
 kit --provider-url "https://my-proxy.example.com/v1" --model openai/gpt-4o
 ```
 
+When `--provider-url` is provided without `--model`, Kit automatically defaults to `custom/custom`:
+
+```bash
+kit --provider-url "http://localhost:8080/v1" "Hello"
+```
+
+The `custom/custom` model has zero cost, 262K context window, and supports reasoning. It routes through fantasy's `openaicompat` provider and accepts any OpenAI-compatible API endpoint.
+
+Optionally set `CUSTOM_API_KEY` environment variable or use `--provider-api-key` for endpoints requiring authentication.
+
 ## Model database
 
 Kit ships with a local model database that maps provider names to API configurations. You can manage it with:

www/pages/sdk/callbacks.md

@@ -113,3 +113,25 @@ host.OnAfterTurn(0, func(ctx context.Context) error {
 ```
 
 The first argument is a priority (lower = runs first).
+
+## Subagent event monitoring
+
+Monitor real-time events from LLM-initiated subagents (when the model uses the `spawn_subagent` tool):
+
+```go
+host.OnToolCall(func(e kit.ToolCallEvent) {
+    if e.ToolName == "spawn_subagent" {
+        host.SubscribeSubagent(e.ToolCallID, func(event kit.Event) {
+            // Receives the same event types as Subscribe(), scoped to the child agent
+            switch ev := event.(type) {
+            case kit.MessageUpdateEvent:
+                fmt.Print(ev.Chunk)
+            case kit.ToolCallEvent:
+                fmt.Printf("Subagent calling: %s\n", ev.ToolName)
+            }
+        })
+    }
+})
+```
+
+`SubscribeSubagent` returns an unsubscribe function. Listeners are also cleaned up automatically when the subagent completes. See [Subagents](/advanced/subagents) for more details.

www/pages/sessions.md

@@ -19,12 +19,31 @@ Path separators in the working directory are replaced with `--`. For example, `/
 
 Each line in the session file is a JSON entry representing a message, tool call, model change, or extension data. The tree structure allows branching from any message to explore alternate paths.
 
+## Compaction
+
+When conversations grow long, Kit can compact them to free up context window space. The compaction system:
+
+- **Non-destructive**: Old messages remain on disk for history; only the LLM context is summarized
+- **File tracking**: Tracks which files were read and modified across compactions
+- **Split-turn handling**: Can summarize large single turns by splitting them
+- **Tool result truncation**: Caps tool output during serialization to stay within token budgets
+
+Use `/compact [focus]` to manually compact, or enable `--auto-compact` to compact automatically near the context limit.
+
+## Auto-cleanup
+
+Kit automatically cleans up empty sessions on shutdown and when using `/resume`. A session is considered empty if it has no messages beyond the initial system prompt. This prevents cluttering your sessions directory with unused files.
+
+To start fresh without creating a session file at all, use ephemeral mode:
+
+```bash
+kit --no-session
+```
+
 ## Resuming sessions
 
 ### Continue most recent
 
-Resume the most recent session for the current directory:
-
 ```bash
 kit --continue
 kit -c
@@ -39,6 +58,8 @@ kit --resume
 kit -r
 ```
 
+The session picker supports search, scope/filter toggles (all sessions vs. current directory), and session deletion. You can also open it during a session with the `/resume` slash command.
+
 ### Open a specific session
 
 ```bash
@@ -46,6 +67,22 @@ kit --session path/to/session.jsonl
 kit -s path/to/session.jsonl
 ```
 
+## Session commands
+
+These slash commands are available during an interactive session:
+
+| Command | Description |
+|---------|-------------|
+| `/name [name]` | Set or display the session's display name |
+| `/session` | Show session info (path, ID, message count) |
+| `/resume` | Open the session picker to switch sessions |
+| `/export [path]` | Export session as JSONL (auto-generates path if omitted) |
+| `/import <path>` | Import and switch to a session from a JSONL file |
+| `/share` | Upload session to GitHub Gist and get a shareable viewer URL |
+| `/tree` | Navigate the session tree |
+| `/fork` | Branch from an earlier message |
+| `/new` | Start a new session (creates new session file) |
+
 ## Ephemeral mode
 
 Run without creating a session file:
@@ -55,3 +92,25 @@ kit --no-session
 ```
 
 This is useful for one-off prompts, scripting, and subagent patterns where persistence isn't needed.
+
+## Sharing sessions
+
+The `/share` command uploads your session JSONL to GitHub Gist (via the `gh` CLI) and prints a shareable viewer URL:
+
+```
+/share
+```
+
+The viewer is available at `https://go-kit.dev/session/#GIST_ID` and supports all message types including text, reasoning blocks, tool calls, images, and model changes.
+
+You can also load any JSONL session via URL parameter: `https://go-kit.dev/session/?url=https://example.com/session.jsonl`
+
+## Preferences persistence
+
+Kit automatically saves your preferences across sessions to `~/.config/kit/preferences.yml`:
+
+- **Theme** — Set via `/theme <name>`
+- **Model** — Set via `/model <name>` or the model selector
+- **Thinking level** — Set via `/thinking <level>` or Shift+Tab cycling
+
+These preferences are restored on next launch. Precedence: CLI flag > config file > saved preference > default.

www/pages/themes.md

@@ -19,6 +19,8 @@ Switch themes at runtime with the `/theme` command:
 
 Run `/theme` with no arguments to list all available themes.
 
+**Theme selections are automatically saved** to `~/.config/kit/preferences.yml` and restored on next launch. You don't need to add anything to your config file — just `/theme <name>` and it sticks. This persistence also applies to **model** and **thinking level** selections.
+
 ## Built-in themes
 
 | Theme | Style |
@@ -276,4 +278,14 @@ When multiple sources define the same theme name, later sources win:
 3. Project-local themes (`.kit/themes/`)
 4. Extension-registered themes (highest)
 
+### Startup theme resolution
+
+At startup, Kit determines which theme to apply:
+
+1. **`.kit.yml` `theme:` key** — explicit config always wins (highest priority)
+2. **`~/.config/kit/preferences.yml`** — persisted `/theme` selection
+3. **Default `kitt` theme** — fallback
+
+The preferences file is updated automatically whenever you use `/theme` or `ctx.SetTheme()`. It is separate from `.kit.yml` so it never clobbers your config comments or formatting.
+
 Theme changes via `/theme` or `ctx.SetTheme()` take effect immediately on all UI elements, including previously rendered messages.