feat: Enhance Gemini integration with smart API detection and model consistency

This release significantly improves the Gemini integration with automatic API
detection, OAuth token refresh, project onboarding, and consistent model defaults
across the codebase.

Major Features:
- Smart base URL detection: Auto-selects Cloud Code API for OAuth users and
  Standard Gemini API for API key users
- Automatic OAuth token refresh with 5-minute buffer before expiry
- Gemini project onboarding flow with polling and persistence
- Racing provider support for concurrent model requests with fallback
- Request/response format adaptation based on authentication type
- Comprehensive metrics tracking and monitoring
- File backup system for write operations

Gemini Improvements:
- Added getBaseURL() method for dynamic API selection
- Added getEndpoint() method for correct endpoint formatting
- Conditional request/response handling (Cloud Code wrapper vs direct format)
- Exported ProjectIDRequiredError with IsProjectIDRequired() helper
- Enhanced logging to show which API is being used
- Project ID persistence to config file to avoid re-onboarding
- Added Content.Role field for proper API compatibility

Model Consistency:
- Standardized default model to gemini-2.0-flash-exp across all locations
- Updated wizard prompts and defaults
- Updated mergeWithExistingConfig() fallback
- Updated generateYAML() fallback
- Added gemini-2.0-flash-exp to provider model list
- Updated GetDefaultModel() return value

Configuration:
- Changed base_url default from hardcoded to empty string for auto-detection
- Enhanced wizard with Gemini OAuth onboarding integration
- Improved config merging for existing configurations
- Added proper OAuth credential handling

API Enhancements:
- Added CloudCodeRequestWrapper and CloudCodeResponseWrapper types
- Implemented LoadCodeAssistRequest/Response types
- Added OnboardUserRequest and LongRunningOperationResponse types
- Enhanced error handling with proper error type exports
- Racing provider with grace period and concurrent model support
- Model selector for intelligent model routing

Infrastructure:
- Added metrics server with Prometheus-style endpoints
- Request/response tracking and statistics
- File backup system for safe write operations
- Enhanced router with racing and fallback support
- Improved logging throughout the codebase

Cleanup:
- Removed test-gemini development command
- Cleaned up temporary test artifacts
- Removed legacy_router.go (replaced by enhanced router)

Breaking Changes: None - all changes maintain backward compatibility

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: cecil-the-coder

cmd/server.go

@@ -10,6 +10,7 @@ import (
 	"github.com/cecil-the-coder/mcp-code-api/internal/config"
 	"github.com/cecil-the-coder/mcp-code-api/internal/logger"
 	"github.com/cecil-the-coder/mcp-code-api/internal/mcp"
+	"github.com/cecil-the-coder/mcp-code-api/internal/metrics"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -49,6 +50,16 @@ The server will:
 		// Load configuration
 		cfg := config.Load()
 
+		// Apply logging configuration from config file
+		logger.SetDebug(cfg.Logging.Debug)
+		logger.SetVerbose(cfg.Logging.Verbose)
+		logger.Debugf("Debug logging enabled: %v", cfg.Logging.Debug)
+		logger.Debugf("Verbose logging enabled: %v", cfg.Logging.Verbose)
+
+		// Log config details now that debug/verbose are enabled
+		logger.Debugf("Preferred provider order: %v", cfg.Providers.Order)
+		logger.Debugf("Enabled providers: %v", cfg.Providers.Enabled)
+
 		// Check API keys availability (log to file only, not stderr)
 		if cfg.Providers.Cerebras == nil || cfg.Providers.Cerebras.APIKey == "" {
 			logger.Info("No Cerebras API key found")
@@ -64,7 +75,8 @@ The server will:
 
 		cerebrasAvail := cfg.Providers.Cerebras != nil && cfg.Providers.Cerebras.APIKey != ""
 		openrouterAvail := cfg.Providers.OpenRouter != nil && cfg.Providers.OpenRouter.APIKey != ""
-		if !cerebrasAvail && !openrouterAvail {
+		geminiAvail := cfg.Providers.Gemini != nil && (cfg.Providers.Gemini.APIKey != "" || cfg.Providers.Gemini.AccessToken != "")
+		if !cerebrasAvail && !openrouterAvail && !geminiAvail {
 			logger.Error("No API keys available")
 			return fmt.Errorf("no API keys configured")
 		}
@@ -88,6 +100,39 @@ The server will:
 		// Start the MCP server
 		server := mcp.NewServer(cfg)
 		logger.Info("MCP Server starting...")
+
+		// Create shared metrics store
+		metricsStore, err := metrics.NewSharedMetricsStore()
+		if err != nil {
+			logger.Warnf("Failed to create shared metrics store: %v", err)
+		} else {
+			// Start periodic metrics updates
+			metricsStore.Start(server.GetRouter())
+			defer metricsStore.Stop()
+		}
+
+		// Start metrics server if enabled
+		var metricsServer *metrics.MetricsServer
+		if cfg.Metrics.Enabled && metricsStore != nil {
+			port := cfg.Metrics.Port
+			if viper.IsSet("metrics_port") && viper.GetInt("metrics_port") != 0 {
+				port = viper.GetInt("metrics_port")
+			}
+
+			metricsServer = metrics.NewMetricsServer(metricsStore, cfg.Metrics.Host, port)
+			if err := metricsServer.Start(); err != nil {
+				logger.Warnf("Failed to start metrics server: %v", err)
+			} else {
+				logger.Infof("Metrics server started on http://%s:%d", cfg.Metrics.Host, port)
+				defer func() {
+					logger.Info("Shutting down metrics server...")
+					if err := metricsServer.Stop(); err != nil {
+						logger.Warnf("Error stopping metrics server: %v", err)
+					}
+				}()
+			}
+		}
+
 		if err := server.Start(ctx); err != nil {
 			return fmt.Errorf("failed to start MCP server: %w", err)
 		}
@@ -104,6 +149,9 @@ func init() {
 	serverCmd.Flags().String("log-file", "", "path to log file")
 	_ = viper.BindPFlag("log_file", serverCmd.Flags().Lookup("log-file"))
 
+	serverCmd.Flags().Int("metrics-port", 0, "port for metrics HTTP server (0 = use config default)")
+	_ = viper.BindPFlag("metrics_port", serverCmd.Flags().Lookup("metrics-port"))
+
 	// Add usage examples
 	serverCmd.SetUsageTemplate(serverCmd.UsageTemplate() + `
 Examples:
@@ -116,8 +164,11 @@ Examples:
   # Start server with custom log file
   mcp-code-api server --log-file /tmp/mcp.log
 
+  # Start server with custom metrics port
+  mcp-code-api server --metrics-port 9090
+
   # Set API keys via environment variables
   CEREBRAS_API_KEY=your_key mcp-code-api server
   OPENROUTER_API_KEY=your_key mcp-code-api server
 `)
-}
+}

go.mod

@@ -1,12 +1,14 @@
 module github.com/cecil-the-coder/mcp-code-api
 
-go 1.21
+go 1.24.0
 
 require (
 	github.com/fatih/color v1.18.0
+	github.com/mitchellh/mapstructure v1.5.0
 	github.com/spf13/cobra v1.8.0
 	github.com/spf13/viper v1.17.0
 	gopkg.in/yaml.v2 v2.4.0
+	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
@@ -16,7 +18,6 @@ require (
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
@@ -28,8 +29,8 @@ require (
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
+	golang.org/x/oauth2 v0.33.0 // indirect
 	golang.org/x/sys v0.25.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -68,6 +68,8 @@ go.uber.org/multierr v1.9.0 h1:7fIwc/ZtS0q++VgcfqFDxSBZVv/Xo49/SYnDFupUwlI=
 go.uber.org/multierr v1.9.0/go.mod h1:X2jQV1h+kxSjClGpnseKVIxpmcjrj7MNnI0bnlfKTVQ=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9 h1:GoHiUyI/Tp2nVkLI2mCxVkOjsbSXD66ic0XW0js0R9g=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9/go.mod h1:S2oDrQGGwySpoQPVqRShND87VCbxmc6bL1Yd2oYrm6k=
+golang.org/x/oauth2 v0.33.0 h1:4Q+qn+E5z8gPRJfmRy7C2gGG3T4jIprK6aSYgTXGRpo=
+golang.org/x/oauth2 v0.33.0/go.mod h1:lzm5WQJQwKZ3nwavOZ3IS5Aulzxi68dUSgRHujetwEA=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.25.0 h1:r+8e+loiHxRqhXVl6ML1nO3l1+oFoWbnlu2Ehimmi34=

internal/api/anthropic.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/cecil-the-coder/mcp-code-api/internal/api/types"
 	"github.com/cecil-the-coder/mcp-code-api/internal/config"
 	"github.com/cecil-the-coder/mcp-code-api/internal/logger"
 	"github.com/cecil-the-coder/mcp-code-api/internal/utils"
@@ -21,6 +22,7 @@ type AnthropicClient struct {
 	config     config.AnthropicConfig
 	client     *http.Client
 	keyManager *APIKeyManager
+	lastUsage  *types.Usage  // Store last token usage
 }
 
 // NewAnthropicClient creates a new Anthropic client
@@ -44,9 +46,9 @@ func NewAnthropicClient(cfg config.AnthropicConfig) *AnthropicClient {
 }
 
 // GenerateCode generates code using the Anthropic API with automatic failover
-func (c *AnthropicClient) GenerateCode(ctx context.Context, prompt, contextStr, outputFile string, language *string, contextFiles []string) (string, error) {
+func (c *AnthropicClient) GenerateCode(ctx context.Context, prompt, contextStr, outputFile string, language *string, contextFiles []string) (*types.CodeGenerationResult, error) {
 	if c.keyManager == nil {
-		return "", fmt.Errorf("no Anthropic API key configured")
+		return nil, fmt.Errorf("no Anthropic API key configured")
 	}
 
 	// Determine language from file extension or explicit parameter
@@ -59,13 +61,22 @@ func (c *AnthropicClient) GenerateCode(ctx context.Context, prompt, contextStr,
 	requestData := c.prepareRequest(fullPrompt, detectedLanguage)
 
 	// Use failover to try multiple API keys if needed
-	return c.keyManager.ExecuteWithFailover(func(apiKey string) (string, error) {
+	code, err := c.keyManager.ExecuteWithFailover(func(apiKey string) (string, error) {
 		// Make the API call with this specific key
 		response, err := c.makeAPICallWithKey(ctx, requestData, apiKey)
 		if err != nil {
 			return "", err
 		}
 
+		// Store usage information
+		c.lastUsage = &types.Usage{
+			PromptTokens:     response.Usage.InputTokens,
+			CompletionTokens: response.Usage.OutputTokens,
+			TotalTokens:      response.Usage.InputTokens + response.Usage.OutputTokens,
+		}
+		logger.Debugf("Anthropic: Extracted token usage - Prompt: %d, Completion: %d, Total: %d",
+			c.lastUsage.PromptTokens, c.lastUsage.CompletionTokens, c.lastUsage.TotalTokens)
+
 		// Extract and clean the content
 		if len(response.Content) == 0 {
 			return "", fmt.Errorf("no content in API response")
@@ -75,6 +86,22 @@ func (c *AnthropicClient) GenerateCode(ctx context.Context, prompt, contextStr,
 
 		return cleanedContent, nil
 	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	// Return result with usage information
+	result := &types.CodeGenerationResult{
+		Code:  code,
+		Usage: c.lastUsage,
+	}
+	if result.Usage != nil {
+		logger.Debugf("Anthropic: Returning result with usage - Total tokens: %d", result.Usage.TotalTokens)
+	} else {
+		logger.Warnf("Anthropic: Returning result with nil usage")
+	}
+	return result, nil
 }
 
 // buildFullPrompt builds the complete prompt including context and existing content

internal/api/apikey_manager.go

@@ -52,6 +52,28 @@ func NewAPIKeyManager(providerName string, keys []string) *APIKeyManager {
 	return manager
 }
 
+// GetCurrentKey returns the first available API key without advancing the round-robin counter
+// This is useful for queries that don't need load balancing (e.g., rate limit checks)
+func (m *APIKeyManager) GetCurrentKey() string {
+	if len(m.keys) == 0 {
+		return ""
+	}
+
+	// Try to find the first available key
+	for _, key := range m.keys {
+		m.mu.RLock()
+		health := m.keyHealth[key]
+		m.mu.RUnlock()
+
+		if m.isKeyAvailable(key, health) {
+			return key
+		}
+	}
+
+	// If all keys are in backoff, return the first key anyway
+	return m.keys[0]
+}
+
 // GetNextKey returns the next available API key using round-robin load balancing
 // It skips keys that are currently in backoff due to failures
 func (m *APIKeyManager) GetNextKey() (string, error) {

internal/api/auth/gemini.go

@@ -3,6 +3,15 @@ package auth
 import (
 	"context"
 	"fmt"
+
+	"github.com/cecil-the-coder/mcp-code-api/internal/oauth"
+)
+
+// Official Google OAuth credentials from llxprt-code project
+// Source: https://github.com/google/llxprt-code
+var (
+	GeminiOAuthClientID     = oauth.GeminiOAuth.ClientID
+	GeminiOAuthClientSecret = oauth.GeminiOAuth.ClientSecret
 )
 
 // GeminiOAuthConfig returns the OAuth configuration for Google Gemini