Feature: #103

feat(gemini): add Gemini thinking configuration support and metadata normalization

- Introduced logic to parse and apply `thinkingBudget` and `include_thoughts` configurations from metadata.
- Enhanced request handling to include normalized Gemini model metadata, preserving the original model identifier.
- Updated Gemini and Gemini-CLI executors to apply thinking configuration based on metadata overrides.
- Refactored handlers to support metadata extraction and cloning during request preparation.

sdk/api/handlers/handlers.go

@@ -133,20 +133,27 @@ func (h *BaseAPIHandler) GetContextWithCancel(handler interfaces.APIHandler, c *
 // ExecuteWithAuthManager executes a non-streaming request via the core auth manager.
 // This path is the only supported execution route.
 func (h *BaseAPIHandler) ExecuteWithAuthManager(ctx context.Context, handlerType, modelName string, rawJSON []byte, alt string) ([]byte, *interfaces.ErrorMessage) {
-	providers := util.GetProviderName(modelName)
+	normalizedModel, metadata := normalizeModelMetadata(modelName)
+	providers := util.GetProviderName(normalizedModel)
 	if len(providers) == 0 {
 		return nil, &interfaces.ErrorMessage{StatusCode: http.StatusBadRequest, Error: fmt.Errorf("unknown provider for model %s", modelName)}
 	}
 	req := coreexecutor.Request{
-		Model:   modelName,
+		Model:   normalizedModel,
 		Payload: cloneBytes(rawJSON),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		req.Metadata = cloned
+	}
 	opts := coreexecutor.Options{
 		Stream:          false,
 		Alt:             alt,
 		OriginalRequest: cloneBytes(rawJSON),
 		SourceFormat:    sdktranslator.FromString(handlerType),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		opts.Metadata = cloned
+	}
 	resp, err := h.AuthManager.Execute(ctx, providers, req, opts)
 	if err != nil {
 		return nil, &interfaces.ErrorMessage{StatusCode: http.StatusInternalServerError, Error: err}
@@ -157,20 +164,27 @@ func (h *BaseAPIHandler) ExecuteWithAuthManager(ctx context.Context, handlerType
 // ExecuteCountWithAuthManager executes a non-streaming request via the core auth manager.
 // This path is the only supported execution route.
 func (h *BaseAPIHandler) ExecuteCountWithAuthManager(ctx context.Context, handlerType, modelName string, rawJSON []byte, alt string) ([]byte, *interfaces.ErrorMessage) {
-	providers := util.GetProviderName(modelName)
+	normalizedModel, metadata := normalizeModelMetadata(modelName)
+	providers := util.GetProviderName(normalizedModel)
 	if len(providers) == 0 {
 		return nil, &interfaces.ErrorMessage{StatusCode: http.StatusBadRequest, Error: fmt.Errorf("unknown provider for model %s", modelName)}
 	}
 	req := coreexecutor.Request{
-		Model:   modelName,
+		Model:   normalizedModel,
 		Payload: cloneBytes(rawJSON),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		req.Metadata = cloned
+	}
 	opts := coreexecutor.Options{
 		Stream:          false,
 		Alt:             alt,
 		OriginalRequest: cloneBytes(rawJSON),
 		SourceFormat:    sdktranslator.FromString(handlerType),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		opts.Metadata = cloned
+	}
 	resp, err := h.AuthManager.ExecuteCount(ctx, providers, req, opts)
 	if err != nil {
 		return nil, &interfaces.ErrorMessage{StatusCode: http.StatusInternalServerError, Error: err}
@@ -181,7 +195,8 @@ func (h *BaseAPIHandler) ExecuteCountWithAuthManager(ctx context.Context, handle
 // ExecuteStreamWithAuthManager executes a streaming request via the core auth manager.
 // This path is the only supported execution route.
 func (h *BaseAPIHandler) ExecuteStreamWithAuthManager(ctx context.Context, handlerType, modelName string, rawJSON []byte, alt string) (<-chan []byte, <-chan *interfaces.ErrorMessage) {
-	providers := util.GetProviderName(modelName)
+	normalizedModel, metadata := normalizeModelMetadata(modelName)
+	providers := util.GetProviderName(normalizedModel)
 	if len(providers) == 0 {
 		errChan := make(chan *interfaces.ErrorMessage, 1)
 		errChan <- &interfaces.ErrorMessage{StatusCode: http.StatusBadRequest, Error: fmt.Errorf("unknown provider for model %s", modelName)}
@@ -189,15 +204,21 @@ func (h *BaseAPIHandler) ExecuteStreamWithAuthManager(ctx context.Context, handl
 		return nil, errChan
 	}
 	req := coreexecutor.Request{
-		Model:   modelName,
+		Model:   normalizedModel,
 		Payload: cloneBytes(rawJSON),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		req.Metadata = cloned
+	}
 	opts := coreexecutor.Options{
 		Stream:          true,
 		Alt:             alt,
 		OriginalRequest: cloneBytes(rawJSON),
 		SourceFormat:    sdktranslator.FromString(handlerType),
 	}
+	if cloned := cloneMetadata(metadata); cloned != nil {
+		opts.Metadata = cloned
+	}
 	chunks, err := h.AuthManager.ExecuteStream(ctx, providers, req, opts)
 	if err != nil {
 		errChan := make(chan *interfaces.ErrorMessage, 1)
@@ -232,6 +253,34 @@ func cloneBytes(src []byte) []byte {
 	return dst
 }
 
+func normalizeModelMetadata(modelName string) (string, map[string]any) {
+	baseModel, budget, include, matched := util.ParseGeminiThinkingSuffix(modelName)
+	if !matched {
+		return baseModel, nil
+	}
+	metadata := map[string]any{
+		util.GeminiOriginalModelMetadataKey: modelName,
+	}
+	if budget != nil {
+		metadata[util.GeminiThinkingBudgetMetadataKey] = *budget
+	}
+	if include != nil {
+		metadata[util.GeminiIncludeThoughtsMetadataKey] = *include
+	}
+	return baseModel, metadata
+}
+
+func cloneMetadata(src map[string]any) map[string]any {
+	if len(src) == 0 {
+		return nil
+	}
+	dst := make(map[string]any, len(src))
+	for k, v := range src {
+		dst[k] = v
+	}
+	return dst
+}
+
 // WriteErrorResponse writes an error message to the response writer using the HTTP status embedded in the message.
 func (h *BaseAPIHandler) WriteErrorResponse(c *gin.Context, msg *interfaces.ErrorMessage) {
 	status := http.StatusInternalServerError