feat(config): per-model baseUrl and apiKey for custom models

- Add `baseUrl` and `apiKey` fields to CustomModelConfig (config and models packages)
- Store them on ModelInfo so they travel through the registry
- createCustomProvider resolves URL/key from model definition first,
  falling back to global --provider-url / --provider-api-key
- Fix registry initialisation: call ReloadGlobalRegistry() in InitConfig()
  so customModels from config are visible on startup (not just at init time)
- Include custom provider in GetLLMProviders() so custom models appear
  in the /model selector
- Hide the built-in custom/custom stub from the selector when user-defined
  custom models are present

cmd/root.go

@@ -154,6 +154,9 @@ func InitConfig() {
 		fmt.Fprintf(os.Stderr, "%v\n", err)
 		os.Exit(1)
 	}
+	// Rebuild the model registry now that viper has the config loaded,
+	// so customModels defined in the config file are picked up.
+	models.ReloadGlobalRegistry()
 }
 
 // LoadConfigWithEnvSubstitution loads a config file with environment variable

internal/config/config.go

@@ -162,6 +162,8 @@ type Theme struct {
 // and merged into the custom provider in the model registry.
 type CustomModelConfig struct {
 	Name        string      `json:"name" yaml:"name"`
+	BaseURL     string      `json:"baseUrl,omitempty" yaml:"baseUrl,omitempty"`
+	APIKey      string      `json:"apiKey,omitempty" yaml:"apiKey,omitempty"`
 	Family      string      `json:"family,omitempty" yaml:"family,omitempty"`
 	Attachment  bool        `json:"attachment,omitempty" yaml:"attachment,omitempty"`
 	Reasoning   bool        `json:"reasoning,omitempty" yaml:"reasoning,omitempty"`

internal/models/custom.go

@@ -37,6 +37,8 @@ func modelConfigToModelInfo(modelID string, cfg CustomModelConfig) ModelInfo {
 		Attachment:  cfg.Attachment,
 		Reasoning:   cfg.Reasoning,
 		Temperature: cfg.Temperature,
+		BaseURL:     cfg.BaseURL,
+		APIKey:      cfg.APIKey,
 		Cost: Cost{
 			Input:  cfg.Cost.Input,
 			Output: cfg.Cost.Output,
@@ -52,6 +54,8 @@ func modelConfigToModelInfo(modelID string, cfg CustomModelConfig) ModelInfo {
 // This is a duplicate here to avoid circular dependencies with internal/config.
 type CustomModelConfig struct {
 	Name        string      `json:"name" yaml:"name"`
+	BaseURL     string      `json:"baseUrl,omitempty" yaml:"baseUrl,omitempty"`
+	APIKey      string      `json:"apiKey,omitempty" yaml:"apiKey,omitempty"`
 	Family      string      `json:"family,omitempty" yaml:"family,omitempty"`
 	Attachment  bool        `json:"attachment,omitempty" yaml:"attachment,omitempty"`
 	Reasoning   bool        `json:"reasoning,omitempty" yaml:"reasoning,omitempty"`

internal/models/providers.go

@@ -1128,11 +1128,23 @@ func customToPromptFunc(prompt fantasy.Prompt, systemPrompt, user string) ([]ope
 }
 
 func createCustomProvider(ctx context.Context, config *ProviderConfig, modelName string) (*ProviderResult, error) {
-	if config.ProviderURL == "" {
-		return nil, fmt.Errorf("custom provider requires --provider-url")
+	// Resolve base URL: per-model override > global provider-url flag/config
+	registry := GetGlobalRegistry()
+	modelInfo := registry.LookupModel("custom", modelName)
+
+	baseURL := config.ProviderURL
+	if modelInfo != nil && modelInfo.BaseURL != "" {
+		baseURL = modelInfo.BaseURL
+	}
+
+	if baseURL == "" {
+		return nil, fmt.Errorf("custom provider requires --provider-url or a baseUrl in the model config")
 	}
 
 	apiKey := config.ProviderAPIKey
+	if modelInfo != nil && modelInfo.APIKey != "" {
+		apiKey = modelInfo.APIKey
+	}
 	if apiKey == "" {
 		apiKey = os.Getenv("CUSTOM_API_KEY")
 	}
@@ -1144,7 +1156,7 @@ func createCustomProvider(ctx context.Context, config *ProviderConfig, modelName
 	// Use the openai provider directly with custom hooks to handle <think> tags
 	// from models like Qwen and DeepSeek that wrap reasoning in XML tags.
 	var opts []openai.Option
-	opts = append(opts, openai.WithBaseURL(config.ProviderURL))
+	opts = append(opts, openai.WithBaseURL(baseURL))
 	opts = append(opts, openai.WithAPIKey(apiKey))
 	opts = append(opts, openai.WithName("custom"))
 	opts = append(opts, openai.WithLanguageModelOptions(

internal/models/registry.go

@@ -24,6 +24,8 @@ type ModelInfo struct {
 	Cost        Cost
 	Limit       Limit
 	ProviderNPM string // Model-specific provider npm override (e.g. "@ai-sdk/anthropic")
+	BaseURL     string // Per-model base URL override (custom models only)
+	APIKey      string // Per-model API key override (custom models only)
 }
 
 // SupportsCaching returns true if this model family supports prompt caching.
@@ -367,8 +369,8 @@ func (r *ModelsRegistry) GetFantasyProviders() []string {
 
 // isProviderLLMSupported checks if a provider can be used with the LLM layer.
 func isProviderLLMSupported(providerID string, info *ProviderInfo) bool {
-	// Ollama is always supported (via openaicompat pointed at localhost)
-	if providerID == "ollama" {
+	// Ollama and custom are always supported (model names are user-defined).
+	if providerID == "ollama" || providerID == "custom" {
 		return true
 	}
 

internal/ui/model_selector.go

@@ -57,7 +57,22 @@ func NewModelSelector(currentModel string, width, height int) *ModelSelectorComp
 			continue
 		}
 
+		// For the custom provider, skip the built-in "custom" stub when
+		// user-defined models are present — the stub is a fallback for
+		// --provider-url usage and would just clutter the list.
+		userDefinedCustomModels := 0
+		if providerID == "custom" {
+			for modelID := range modelsMap {
+				if modelID != "custom" {
+					userDefinedCustomModels++
+				}
+			}
+		}
+
 		for modelID, info := range modelsMap {
+			if providerID == "custom" && modelID == "custom" && userDefinedCustomModels > 0 {
+				continue
+			}
 			allModels = append(allModels, ModelEntry{
 				Provider:     providerID,
 				ModelID:      modelID,

www/pages/configuration.md

@@ -104,6 +104,8 @@ Define custom models in your `.kit.yml` for use with the `custom` provider. This
 customModels:
   my-model:
     name: "My Custom Model"
+    baseUrl: "http://localhost:8080/v1"
+    apiKey: "my-secret-key"
     reasoning: true
     temperature: true
     cost:
@@ -119,6 +121,8 @@ customModels:
 | Field | Type | Required | Description |
 |-------|------|----------|-------------|
 | `name` | string | Yes | Display name for the model |
+| `baseUrl` | string | No | Per-model base URL override; when set, `--provider-url` is not required |
+| `apiKey` | string | No | Per-model API key override |
 | `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 |
@@ -126,7 +130,13 @@ customModels:
 | `limit.context` | int | Yes | Maximum context window in tokens |
 | `limit.output` | int | No | Maximum output tokens |
 
-Use with a custom provider URL:
+Use with a per-model `baseUrl` (no `--provider-url` needed):
+
+```bash
+kit --model custom/my-model "Hello"
+```
+
+Or override the base URL at runtime:
 
 ```bash
 kit --provider-url "http://localhost:8080/v1" --model custom/my-model "Hello"