feat: add Anthropic provider integration with Claude Code CLI

- Add AnthropicProvider that executes Claude Code CLI with Haiku 4.5 model
- Implement configurable number of commit message suggestions
- Skip API key requirement for Anthropic provider (uses CLI authentication)
- Add Claude Haiku 4.5 model definition to models registry
- Update config system to support Anthropic-specific settings
- Extend interactive config to include Anthropic provider option

The Anthropic provider leverages the local Claude Code CLI installation,
eliminating the need for API key management while providing fast commit
message generation using the Haiku model.

Author: lcarrasco

cmd/commit.go

@@ -40,14 +40,20 @@ var commitCmd = &cobra.Command{
 		var aiProvider CommitProvider
 
 		providerName := config.GetProvider()
-		apiKey, err := config.GetAPIKey()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "Error getting API key: %v\n", err)
-			os.Exit(1)
+
+		// API key is not needed for anthropic provider (uses CLI)
+		var apiKey string
+		if providerName != "anthropic" {
+			var err error
+			apiKey, err = config.GetAPIKey()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Error getting API key: %v\n", err)
+				os.Exit(1)
+			}
 		}
 
 		var model string
-		if providerName == "copilot" || providerName == "openai" {
+		if providerName == "copilot" || providerName == "openai" || providerName == "anthropic" {
 			var err error
 			model, err = config.GetModel()
 			if err != nil {
@@ -67,6 +73,13 @@ var commitCmd = &cobra.Command{
 			aiProvider = provider.NewCopilotProviderWithModel(apiKey, model, endpoint)
 		case "openai":
 			aiProvider = provider.NewOpenAIProvider(apiKey, model, endpoint)
+		case "anthropic":
+			// Get num_suggestions from config (default to 10)
+			numSuggestions := config.GetNumSuggestions()
+			if numSuggestions <= 0 {
+				numSuggestions = 10
+			}
+			aiProvider = provider.NewAnthropicProvider(model, numSuggestions)
 		default:
 			// Default to copilot if provider is not set or unknown
 			aiProvider = provider.NewCopilotProvider(apiKey, endpoint)

cmd/config.go

@@ -79,7 +79,7 @@ func runInteractiveConfig() {
 
 	providerPrompt := &survey.Select{
 		Message: "Choose a provider:",
-		Options: []string{"openai", "copilot"},
+		Options: []string{"openai", "copilot", "anthropic"},
 		Default: currentProvider,
 	}
 	var selectedProvider string
@@ -99,7 +99,8 @@ func runInteractiveConfig() {
 		currentModel = ""
 	}
 
-	if selectedProvider != "copilot" {
+	// API key configuration - skip for copilot and anthropic
+	if selectedProvider != "copilot" && selectedProvider != "anthropic" {
 		apiKeyPrompt := &survey.Input{
 			Message: fmt.Sprintf("Enter API Key for %s:", selectedProvider),
 		}
@@ -117,21 +118,31 @@ func runInteractiveConfig() {
 			}
 			fmt.Printf("API key for %s set.\n", selectedProvider)
 		}
+	} else if selectedProvider == "anthropic" {
+		fmt.Println("Anthropic provider uses Claude Code CLI - no API key needed.")
 	}
 
-	// Dynamically generate available models for OpenAI
+	// Dynamically generate available models
 	availableModels := map[string][]string{
-		"openai":  {},
-		"copilot": {"openai/gpt-5-mini"}, // TODO: update if copilot models are dynamic
+		"openai":    {},
+		"copilot":   {"openai/gpt-5-mini"},
+		"anthropic": {},
 	}
 
 	modelDisplayToID := map[string]string{}
+
 	if selectedProvider == "openai" {
 		for id, m := range models.OpenAIModels {
 			display := fmt.Sprintf("%s (%s)", m.Name, string(id))
 			availableModels["openai"] = append(availableModels["openai"], display)
 			modelDisplayToID[display] = string(id)
 		}
+	} else if selectedProvider == "anthropic" {
+		for _, m := range models.AnthropicModels {
+			display := fmt.Sprintf("%s (%s)", m.Name, m.APIModel)
+			availableModels["anthropic"] = append(availableModels["anthropic"], display)
+			modelDisplayToID[display] = m.APIModel
+		}
 	}
 
 	modelPrompt := &survey.Select{
@@ -142,7 +153,7 @@ func runInteractiveConfig() {
 	// Try to set the default to the current model if possible
 	isValidDefault := false
 	currentDisplay := ""
-	if selectedProvider == "openai" {
+	if selectedProvider == "openai" || selectedProvider == "anthropic" {
 		for display, id := range modelDisplayToID {
 			if id == currentModel || display == currentModel {
 				isValidDefault = true
@@ -171,7 +182,7 @@ func runInteractiveConfig() {
 	}
 
 	selectedModel := selectedDisplay
-	if selectedProvider == "openai" {
+	if selectedProvider == "openai" || selectedProvider == "anthropic" {
 		selectedModel = modelDisplayToID[selectedDisplay]
 	}
 
@@ -184,31 +195,55 @@ func runInteractiveConfig() {
 		fmt.Printf("Model set to: %s\n", selectedModel)
 	}
 
+	// Number of suggestions configuration for anthropic
+	if selectedProvider == "anthropic" {
+		numSuggestionsPrompt := &survey.Input{
+			Message: "Number of commit message suggestions (default: 10):",
+			Default: "10",
+		}
+		var numSuggestions string
+		err := survey.AskOne(numSuggestionsPrompt, &numSuggestions)
+		if err != nil {
+			fmt.Println(err.Error())
+			return
+		}
+		if numSuggestions != "" {
+			err := config.SetNumSuggestions(selectedProvider, numSuggestions)
+			if err != nil {
+				fmt.Printf("Error setting num_suggestions: %v\n", err)
+				return
+			}
+			fmt.Printf("Number of suggestions set to: %s\n", numSuggestions)
+		}
+	}
+
 	// Get current endpoint
 	currentEndpoint, _ := config.GetEndpoint()
 
-	// Endpoint configuration prompt
-	endpointPrompt := &survey.Input{
-		Message: "Enter custom endpoint URL (leave empty for default):",
-		Default: currentEndpoint,
-	}
-	var endpoint string
-	err = survey.AskOne(endpointPrompt, &endpoint, survey.WithValidator(validateEndpointURL))
-	if err != nil {
-		fmt.Println(err.Error())
-		return
-	}
-
-	// Only set endpoint if it's different from current
-	if endpoint != currentEndpoint && endpoint != "" {
-		err := config.SetEndpoint(selectedProvider, endpoint)
+	// Endpoint configuration prompt - skip for anthropic since it uses CLI
+	if selectedProvider != "anthropic" {
+		endpointPrompt := &survey.Input{
+			Message: "Enter custom endpoint URL (leave empty for default):",
+			Default: currentEndpoint,
+		}
+		var endpoint string
+		err = survey.AskOne(endpointPrompt, &endpoint, survey.WithValidator(validateEndpointURL))
 		if err != nil {
-			fmt.Printf("Error setting endpoint: %v\n", err)
+			fmt.Println(err.Error())
 			return
 		}
-		fmt.Printf("Endpoint set to: %s\n", endpoint)
-	} else if endpoint == "" {
-		fmt.Println("Using default endpoint for provider")
+
+		// Only set endpoint if it's different from current
+		if endpoint != currentEndpoint && endpoint != "" {
+			err := config.SetEndpoint(selectedProvider, endpoint)
+			if err != nil {
+				fmt.Printf("Error setting endpoint: %v\n", err)
+				return
+			}
+			fmt.Printf("Endpoint set to: %s\n", endpoint)
+		} else if endpoint == "" {
+			fmt.Println("Using default endpoint for provider")
+		}
 	}
 }
 

internal/config/config.go

@@ -14,9 +14,10 @@ import (
 )
 
 type ProviderConfig struct {
-	APIKey      string `mapstructure:"api_key"`
-	Model       string `mapstructure:"model"`
-	EndpointURL string `mapstructure:"endpoint_url"`
+	APIKey         string `mapstructure:"api_key"`
+	Model          string `mapstructure:"model"`
+	EndpointURL    string `mapstructure:"endpoint_url"`
+	NumSuggestions int    `mapstructure:"num_suggestions"`
 }
 
 type Config struct {
@@ -41,6 +42,10 @@ func InitConfig() {
 		viper.SetDefault("providers.openai.model", "openai/gpt-5-mini")
 	}
 
+	// Set defaults for anthropic provider
+	viper.SetDefault("providers.anthropic.model", "claude-haiku-4-5")
+	viper.SetDefault("providers.anthropic.num_suggestions", 10)
+
 	viper.AutomaticEnv()
 
 	if err := viper.ReadInConfig(); err != nil {
@@ -144,6 +149,8 @@ func GetEndpoint() (string, error) {
 		return "https://api.openai.com/v1", nil
 	case "copilot":
 		return "https://api.githubcopilot.com", nil
+	case "anthropic":
+		return "", nil // Anthropic uses CLI, no endpoint needed
 	default:
 		return "", fmt.Errorf("no default endpoint available for provider '%s'", cfg.ActiveProvider)
 	}
@@ -257,6 +264,28 @@ func tryGetTokenFromGHCLI() (string, error) {
 	return tok, nil
 }
 
+func GetNumSuggestions() int {
+	if cfg == nil {
+		InitConfig()
+	}
+	providerConfig, err := GetActiveProviderConfig()
+	if err != nil {
+		return 10 // Default to 10 if error
+	}
+	if providerConfig.NumSuggestions <= 0 {
+		return 10 // Default to 10 if not set or invalid
+	}
+	return providerConfig.NumSuggestions
+}
+
+func SetNumSuggestions(provider, numSuggestions string) error {
+	if cfg == nil {
+		InitConfig()
+	}
+	viper.Set(fmt.Sprintf("providers.%s.num_suggestions", provider), numSuggestions)
+	return viper.WriteConfig()
+}
+
 func getConfigDir() string {
 	if xdgConfig := os.Getenv("XDG_CONFIG_HOME"); xdgConfig != "" {
 		return xdgConfig

internal/provider/anthropic.go

@@ -0,0 +1,111 @@
+package provider
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+type AnthropicProvider struct {
+	model          string
+	numSuggestions int
+}
+
+func NewAnthropicProvider(model string, numSuggestions int) *AnthropicProvider {
+	if model == "" {
+		model = "claude-haiku-4-5"
+	}
+	if numSuggestions <= 0 {
+		numSuggestions = 10
+	}
+	return &AnthropicProvider{
+		model:          model,
+		numSuggestions: numSuggestions,
+	}
+}
+
+func (a *AnthropicProvider) GenerateCommitMessage(ctx context.Context, diff string) (string, error) {
+	msgs, err := a.GenerateCommitMessages(ctx, diff)
+	if err != nil {
+		return "", err
+	}
+	if len(msgs) == 0 {
+		return "", fmt.Errorf("no commit messages generated")
+	}
+	return msgs[0], nil
+}
+
+func (a *AnthropicProvider) GenerateCommitMessages(ctx context.Context, diff string) ([]string, error) {
+	if strings.TrimSpace(diff) == "" {
+		return nil, fmt.Errorf("no diff provided")
+	}
+
+	// Check if claude CLI is available
+	if _, err := exec.LookPath("claude"); err != nil {
+		return nil, fmt.Errorf("claude CLI not found in PATH. Please install Claude Code CLI: %w", err)
+	}
+
+	// Build the prompt
+	systemMsg := GetSystemMessage()
+	userPrompt := GetCommitMessagePrompt(diff)
+
+	// Modify the prompt to request specific number of suggestions
+	fullPrompt := fmt.Sprintf("%s\n\nUser request: %s\n\nIMPORTANT: Generate exactly %d commit messages, one per line. Do not include any other text, explanations, or formatting - just the commit messages.",
+		systemMsg, userPrompt, a.numSuggestions)
+
+	// Execute claude CLI with haiku model
+	// Using -p flag for print mode and --model for model selection
+	cmd := exec.CommandContext(ctx, "claude", "--model", a.model, "-p", fullPrompt)
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("error executing claude CLI: %w\nOutput: %s", err, string(output))
+	}
+
+	// Parse the output - split by newlines and clean
+	content := string(output)
+	lines := strings.Split(content, "\n")
+
+	var commitMessages []string
+	for _, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		// Skip empty lines and lines that look like explanatory text
+		if trimmed == "" {
+			continue
+		}
+		// Skip lines that are clearly not commit messages (too long, contain certain patterns)
+		if len(trimmed) > 200 {
+			continue
+		}
+		// Skip markdown formatting or numbered lists
+		if strings.HasPrefix(trimmed, "#") || strings.HasPrefix(trimmed, "-") || strings.HasPrefix(trimmed, "*") {
+			// Try to extract the actual commit message
+			parts := strings.SplitN(trimmed, " ", 2)
+			if len(parts) == 2 {
+				trimmed = strings.TrimSpace(parts[1])
+			}
+		}
+		// Remove numbered list formatting like "1. " or "1) "
+		if len(trimmed) > 3 {
+			if (trimmed[0] >= '0' && trimmed[0] <= '9') && (trimmed[1] == '.' || trimmed[1] == ')') {
+				trimmed = strings.TrimSpace(trimmed[2:])
+			}
+		}
+
+		if trimmed != "" {
+			commitMessages = append(commitMessages, trimmed)
+		}
+
+		// Stop once we have enough messages
+		if len(commitMessages) >= a.numSuggestions {
+			break
+		}
+	}
+
+	if len(commitMessages) == 0 {
+		return nil, fmt.Errorf("no valid commit messages generated from Claude output")
+	}
+
+	return commitMessages, nil
+}