feat(provider): add Gemini provider support via Gemini CLI

- Introduce new Gemini provider for generating commit messages and PR reviews.
- Update configuration wizard to support Gemini model selection and options.
- Add supported Gemini models (Flash, Pro, Flash Lite, etc.) to the models package.
- Update README.md with configuration instructions for the new provider.

Author: stn1slv

README.md

@@ -93,6 +93,9 @@ providers:
   anthropic:
     model: "claude-haiku-4-5"  # Uses Claude Code CLI - no API key needed
     num_suggestions: 10        # Number of commit suggestions to generate
+  gemini:
+    model: "flash"             # Uses Gemini CLI - no API key needed
+    num_suggestions: 10        # Number of commit suggestions to generate
 ```
 
 > [!NOTE]

cmd/commit.go

@@ -80,6 +80,12 @@ var commitCmd = &cobra.Command{
 				numSuggestions = 10
 			}
 			aiProvider = provider.NewAnthropicProvider(model, numSuggestions)
+		case "gemini":
+			numSuggestions := config.GetNumSuggestions()
+			if numSuggestions <= 0 {
+				numSuggestions = 10
+			}
+			aiProvider = provider.NewGeminiProvider(model, numSuggestions)
 		default:
 			// Default to copilot if provider is not set or unknown
 			aiProvider = provider.NewCopilotProvider(apiKey, endpoint)

cmd/config.go

@@ -81,7 +81,7 @@ func runInteractiveConfig() {
 
 	providerPrompt := &survey.Select{
 		Message: "Choose a provider:",
-		Options: []string{"openai", "copilot", "anthropic"},
+		Options: []string{"openai", "copilot", "anthropic", "gemini"},
 		Default: currentProvider,
 	}
 	var selectedProvider string
@@ -152,8 +152,8 @@ func runInteractiveConfig() {
 		fmt.Printf("Language set to: %s\n", langValue)
 	}
 
-	// API key configuration - skip for copilot and anthropic
-	if selectedProvider != "copilot" && selectedProvider != "anthropic" {
+	// API key configuration - skip for copilot, anthropic and gemini
+	if selectedProvider != "copilot" && selectedProvider != "anthropic" && selectedProvider != "gemini" {
 		apiKeyPrompt := &survey.Input{
 			Message: fmt.Sprintf("Enter API Key for %s:", selectedProvider),
 		}
@@ -173,12 +173,15 @@ func runInteractiveConfig() {
 		}
 	} else if selectedProvider == "anthropic" {
 		fmt.Println("Anthropic provider uses Claude Code CLI - no API key needed.")
+	} else if selectedProvider == "gemini" {
+		fmt.Println("Gemini provider uses Gemini CLI - no API key needed.")
 	}
 
 	availableModels := map[string][]string{
 		"openai":    {},
 		"copilot":   {},
 		"anthropic": {},
+		"gemini":    {},
 	}
 
 	modelDisplayToID := map[string]string{}
@@ -213,6 +216,12 @@ func runInteractiveConfig() {
 			availableModels["anthropic"] = append(availableModels["anthropic"], display)
 			modelDisplayToID[display] = m.APIModel
 		}
+	case "gemini":
+		for _, m := range models.GeminiModels {
+			display := fmt.Sprintf("%s (%s)", m.Name, m.APIModel)
+			availableModels["gemini"] = append(availableModels["gemini"], display)
+			modelDisplayToID[display] = m.APIModel
+		}
 	}
 
 	modelPrompt := &survey.Select{
@@ -223,7 +232,7 @@ func runInteractiveConfig() {
 	// Try to set the default to the current model if possible
 	isValidDefault := false
 	currentDisplay := ""
-	if selectedProvider == "openai" || selectedProvider == "anthropic" || selectedProvider == "copilot" {
+	if selectedProvider == "openai" || selectedProvider == "anthropic" || selectedProvider == "copilot" || selectedProvider == "gemini" {
 		for display, id := range modelDisplayToID {
 			if id == currentModel || display == currentModel {
 				isValidDefault = true
@@ -252,7 +261,7 @@ func runInteractiveConfig() {
 	}
 
 	selectedModel := selectedDisplay
-	if selectedProvider == "openai" || selectedProvider == "anthropic" || selectedProvider == "copilot" {
+	if selectedProvider == "openai" || selectedProvider == "anthropic" || selectedProvider == "copilot" || selectedProvider == "gemini" {
 		selectedModel = modelDisplayToID[selectedDisplay]
 	}
 
@@ -265,8 +274,8 @@ func runInteractiveConfig() {
 		fmt.Printf("Model set to: %s\n", selectedModel)
 	}
 
-	// Number of suggestions configuration for anthropic
-	if selectedProvider == "anthropic" {
+	// Number of suggestions configuration for anthropic and gemini
+	if selectedProvider == "anthropic" || selectedProvider == "gemini" {
 		numSuggestionsPrompt := &survey.Input{
 			Message: "Number of commit message suggestions (default: 10):",
 			Default: "10",
@@ -290,8 +299,8 @@ func runInteractiveConfig() {
 	// Get current endpoint
 	currentEndpoint, _ := config.GetEndpoint()
 
-	// Endpoint configuration prompt - skip for anthropic since it uses CLI
-	if selectedProvider != "anthropic" {
+	// Endpoint configuration prompt - skip for anthropic and gemini since they use CLI
+	if selectedProvider != "anthropic" && selectedProvider != "gemini" {
 		endpointPrompt := &survey.Input{
 			Message: "Enter custom endpoint URL (leave empty for default):",
 			Default: currentEndpoint,

cmd/pr.go

@@ -87,6 +87,9 @@ var prCmd = &cobra.Command{
 			// Get num_suggestions from config
 			numSuggestions := config.GetNumSuggestions()
 			aiProvider = provider.NewAnthropicProvider(model, numSuggestions)
+		case "gemini":
+			numSuggestions := config.GetNumSuggestions()
+			aiProvider = provider.NewGeminiProvider(model, numSuggestions)
 		default:
 			// Default to copilot if provider is not set or unknown
 			aiProvider = provider.NewCopilotProvider(apiKey, endpoint)

internal/config/config.go

@@ -45,6 +45,8 @@ func InitConfig() {
 
 	viper.SetDefault("providers.anthropic.model", "claude-haiku-4-5")
 	viper.SetDefault("providers.anthropic.num_suggestions", 10)
+	viper.SetDefault("providers.gemini.model", "flash")
+	viper.SetDefault("providers.gemini.num_suggestions", 10)
 	viper.AutomaticEnv()
 
 	if err := viper.ReadInConfig(); err != nil {
@@ -149,6 +151,8 @@ func GetEndpoint() (string, error) {
 		return "https://api.githubcopilot.com", nil
 	case "anthropic":
 		return "", nil // Anthropic uses CLI, no endpoint needed
+	case "gemini":
+		return "", nil // Gemini uses CLI, no endpoint needed
 	default:
 		return "", fmt.Errorf("no default endpoint available for provider '%s'", cfg.ActiveProvider)
 	}

internal/config/config_test.go

@@ -162,8 +162,8 @@ func TestGetEndpoint_CustomEndpoint(t *testing.T) {
 		cfg.Providers = make(map[string]ProviderConfig)
 	}
 	cfg.Providers[testProvider] = ProviderConfig{
-		APIKey:     "test-key",
-		Model:      "test-model",
+		APIKey:      "test-key",
+		Model:       "test-model",
 		EndpointURL: customEndpoint,
 	}
 
@@ -221,12 +221,12 @@ func TestSetEndpoint_Validation(t *testing.T) {
 		endpoint string
 		valid    bool
 	}{
-		{"", true},                           // Empty should be valid (default)
-		{"https://api.openai.com/v1", true},  // Valid HTTPS URL
-		{"http://localhost:11434", true},     // Valid HTTP URL
-		{"ftp://invalid.com", false},         // Invalid protocol
-		{"not-a-url", false},                 // Invalid format
-		{"https://", false},                  // Missing host
+		{"", true},                          // Empty should be valid (default)
+		{"https://api.openai.com/v1", true}, // Valid HTTPS URL
+		{"http://localhost:11434", true},    // Valid HTTP URL
+		{"ftp://invalid.com", false},        // Invalid protocol
+		{"not-a-url", false},                // Invalid format
+		{"https://", false},                 // Missing host
 	}
 
 	for _, tc := range testCases {
@@ -237,4 +237,4 @@ func TestSetEndpoint_Validation(t *testing.T) {
 			t.Errorf("Expected invalid endpoint %s to fail, but it passed", tc.endpoint)
 		}
 	}
-}
+}