kit/examples/extensions/README.md

Kit Extension Examples

A collection of example extensions demonstrating various Kit capabilities. These can be installed individually or as a complete collection.

Installation

Install all examples

kit install github.com/mark3labs/kit/examples/extensions

Install with interactive selection

kit install github.com/mark3labs/kit/examples/extensions --select

Install locally in your project

kit install github.com/mark3labs/kit/examples/extensions --local

Extension Index

Core Concepts

Extension	Description	Key API
minimal.go	Minimal viable extension	Basic Init() function
plan-mode.go	Restrict agent to read-only tools	OnBeforeAgentStart, SetActiveTools
tool-logger.go	Log all tool calls to file	OnToolCall, OnToolResult
notify.go	Display notifications	PrintInfo, PrintBlock

UI & Widgets

Extension	Description	Key API
widget-status.go	Persistent status widget	SetWidget, RemoveWidget
header-footer-demo.go	Custom header/footer	SetHeader, SetFooter
overlay-demo.go	Modal overlay dialogs	ShowOverlay
compact-notify.go	Compact mode notifications	PrintBlock
branded-output.go	Custom styled output	PrintBlock with colors

Input & Editor

Extension	Description	Key API
custom-editor-demo.go	Custom key handling	SetEditor, EditorKeyAction
pirate.go	Transform user input	OnInput, InputResult
interactive-shell.go	Custom command input	Slash commands with prompts
inline-bash.go	Execute bash inline	Input handling, exec

Session & Context

Extension	Description	Key API
context-inject.go	Inject context into prompts	OnContextPrepare
bookmark.go	Bookmark messages	AppendEntry, GetEntries
project-rules.go	Project-specific rules	Session data, file reading
protected-paths.go	Block dangerous operations	OnToolCall with blocking
permission-gate.go	Confirm destructive actions	OnToolCall with confirmation

Tools & Commands

Extension	Description	Key API
auto-commit.go	Auto-commit changes	Custom tool, git operations
summarize.go	Summarize conversation	Custom tool with parameters
confirm-destructive.go	Confirm destructive commands	OnToolCall blocking
lsp-diagnostics.go	LSP integration	Complex extension, external process

Subagents & Background Tasks

Extension	Description	Key API
kit-kit.go	Spawn Kit as subagent	Subagent spawning
subagent-test.go	Test subagent functionality	SpawnSubagent
subagent-widget.go	Widget with subagent updates	Goroutines + widgets
dev-reload.go	Hot reload extensions	ReloadExtensions

Rendering

Extension	Description	Key API
tool-renderer-demo.go	Custom tool output styling	RegisterToolRenderer
prompt-demo.go	Interactive prompts	PromptSelect, PromptConfirm

Extension Details

minimal.go

The bare minimum extension showing the required structure:

• Package main
• Import kit/ext
• Export Init(api ext.API) function

plan-mode.go

A complete example demonstrating:

• Slash command (/plan)
• Keyboard shortcut (ctrl+alt+p)
• Option registration
• Status bar indicators
• System prompt injection
• Tool filtering

widget-status.go

Shows how to create persistent UI elements:

• Create widgets with SetWidget
• Update content dynamically
• Remove when done
• Handle session lifecycle

context-inject.go

Advanced context manipulation:

• Read project files
• Inject into LLM context
• Filter messages
• Use negative indices for ephemeral content

lsp-diagnostics.go

Complex real-world example:

• Multi-file extension
• External process management (LSP server)
• File watching
• Diagnostics aggregation

Multi-File Extension Example

The kit-kit-agents/ directory demonstrates the multi-file pattern:

kit-kit-agents/
├── main.go          # Entry point with Init()
├── agent.go         # Agent configuration
├── manager.go       # Agent lifecycle management
└── README.md        # Documentation

When the repo is installed, all files in subdirectories with main.go are loaded as separate extensions.

Testing & Validation

After installing, test the extensions:

# List all loaded extensions
kit extensions list

# Validate all extensions
kit extensions validate

# Run with a specific extension
kit -e ~/.local/share/kit/git/github.com/mark3labs/kit/examples/extensions/plan-mode.go

Creating Your Own

1. Copy minimal.go as a starting point
2. Modify the Init() function to register your handlers
3. Use the other examples for reference on specific APIs
4. Test with kit -e your-extension.go
5. Share by pushing to a git repository!

Update

To get the latest examples:

kit install github.com/mark3labs/kit/examples/extensions --update

See Also

• Kit Extensions Guide
• API Reference
• Example Extensions Source