feat: Add Gemini adapter, improve API key fallback for Gemini AI Studio compatibility, and enhance OpenAI tool call streaming.

internal/adapter/claude/handler.go

@@ -38,6 +38,10 @@ func RegisterRoutes(r chi.Router, h *Handler) {
 	r.Get("/anthropic/v1/models", h.ListModels)
 	r.Post("/anthropic/v1/messages", h.Messages)
 	r.Post("/anthropic/v1/messages/count_tokens", h.CountTokens)
+	r.Post("/v1/messages", h.Messages)
+	r.Post("/messages", h.Messages)
+	r.Post("/v1/messages/count_tokens", h.CountTokens)
+	r.Post("/messages/count_tokens", h.CountTokens)
 }
 
 func (h *Handler) ListModels(w http.ResponseWriter, _ *http.Request) {
@@ -167,7 +171,7 @@ func (h *Handler) handleClaudeStreamRealtime(w http.ResponseWriter, r *http.Requ
 	w.Header().Set("Connection", "keep-alive")
 	w.Header().Set("X-Accel-Buffering", "no")
 	rc := http.NewResponseController(w)
-	canFlush := rc.Flush() == nil
+	_, canFlush := w.(http.Flusher)
 	if !canFlush {
 		config.Logger.Warn("[claude_stream] response writer does not support flush; streaming may be buffered")
 	}

internal/adapter/claude/route_alias_test.go

@@ -0,0 +1,44 @@
+package claude
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"ds2api/internal/auth"
+)
+
+type routeAliasAuthStub struct{}
+
+func (routeAliasAuthStub) Determine(_ *http.Request) (*auth.RequestAuth, error) {
+	return nil, auth.ErrUnauthorized
+}
+
+func (routeAliasAuthStub) Release(_ *auth.RequestAuth) {}
+
+func TestClaudeRouteAliasesDoNot404(t *testing.T) {
+	h := &Handler{
+		Auth: routeAliasAuthStub{},
+	}
+	r := chi.NewRouter()
+	RegisterRoutes(r, h)
+
+	paths := []string{
+		"/anthropic/v1/messages",
+		"/v1/messages",
+		"/messages",
+		"/anthropic/v1/messages/count_tokens",
+		"/v1/messages/count_tokens",
+		"/messages/count_tokens",
+	}
+	for _, path := range paths {
+		req := httptest.NewRequest(http.MethodPost, path, nil)
+		rec := httptest.NewRecorder()
+		r.ServeHTTP(rec, req)
+		if rec.Code == http.StatusNotFound {
+			t.Fatalf("expected route %s to be registered, got 404", path)
+		}
+	}
+}

internal/adapter/gemini/convert.go

@@ -0,0 +1,313 @@
+package gemini
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"ds2api/internal/adapter/openai"
+	"ds2api/internal/config"
+	"ds2api/internal/util"
+)
+
+func normalizeGeminiRequest(store ConfigReader, routeModel string, req map[string]any, stream bool) (util.StandardRequest, error) {
+	requestedModel := strings.TrimSpace(routeModel)
+	if requestedModel == "" {
+		return util.StandardRequest{}, fmt.Errorf("model is required in request path")
+	}
+
+	resolvedModel, ok := config.ResolveModel(store, requestedModel)
+	if !ok {
+		return util.StandardRequest{}, fmt.Errorf("Model '%s' is not available.", requestedModel)
+	}
+	thinkingEnabled, searchEnabled, _ := config.GetModelConfig(resolvedModel)
+
+	messagesRaw := geminiMessagesFromRequest(req)
+	if len(messagesRaw) == 0 {
+		return util.StandardRequest{}, fmt.Errorf("Request must include non-empty contents.")
+	}
+
+	toolsRaw := convertGeminiTools(req["tools"])
+	finalPrompt, toolNames := openai.BuildPromptForAdapter(messagesRaw, toolsRaw, "")
+	passThrough := collectGeminiPassThrough(req)
+
+	return util.StandardRequest{
+		Surface:        "google_gemini",
+		RequestedModel: requestedModel,
+		ResolvedModel:  resolvedModel,
+		ResponseModel:  requestedModel,
+		Messages:       messagesRaw,
+		FinalPrompt:    finalPrompt,
+		ToolNames:      toolNames,
+		Stream:         stream,
+		Thinking:       thinkingEnabled,
+		Search:         searchEnabled,
+		PassThrough:    passThrough,
+	}, nil
+}
+
+func geminiMessagesFromRequest(req map[string]any) []any {
+	out := make([]any, 0, 8)
+	if sys := normalizeGeminiSystemInstruction(req["systemInstruction"]); strings.TrimSpace(sys) != "" {
+		out = append(out, map[string]any{
+			"role":    "system",
+			"content": sys,
+		})
+	}
+
+	contents, _ := req["contents"].([]any)
+	for _, item := range contents {
+		content, ok := item.(map[string]any)
+		if !ok {
+			continue
+		}
+		role := mapGeminiRole(content["role"])
+		if role == "" {
+			role = "user"
+		}
+		parts, _ := content["parts"].([]any)
+		if len(parts) == 0 {
+			if text := strings.TrimSpace(asString(content["text"])); text != "" {
+				out = append(out, map[string]any{
+					"role":    role,
+					"content": text,
+				})
+			}
+			continue
+		}
+
+		textParts := make([]string, 0, len(parts))
+		flushText := func() {
+			if len(textParts) == 0 {
+				return
+			}
+			out = append(out, map[string]any{
+				"role":    role,
+				"content": strings.Join(textParts, "\n"),
+			})
+			textParts = textParts[:0]
+		}
+
+		for _, rawPart := range parts {
+			part, ok := rawPart.(map[string]any)
+			if !ok {
+				continue
+			}
+			if text := strings.TrimSpace(asString(part["text"])); text != "" {
+				textParts = append(textParts, text)
+				continue
+			}
+
+			if fnCall, ok := part["functionCall"].(map[string]any); ok {
+				flushText()
+				if name := strings.TrimSpace(asString(fnCall["name"])); name != "" {
+					callID := strings.TrimSpace(asString(fnCall["id"]))
+					if callID == "" {
+						callID = "call_gemini"
+					}
+					out = append(out, map[string]any{
+						"role": "assistant",
+						"tool_calls": []any{
+							map[string]any{
+								"id":   callID,
+								"type": "function",
+								"function": map[string]any{
+									"name":      name,
+									"arguments": stringifyJSON(fnCall["args"]),
+								},
+							},
+						},
+					})
+				}
+				continue
+			}
+
+			if fnResp, ok := part["functionResponse"].(map[string]any); ok {
+				flushText()
+				name := strings.TrimSpace(asString(fnResp["name"]))
+				callID := strings.TrimSpace(asString(fnResp["id"]))
+				if callID == "" {
+					callID = strings.TrimSpace(asString(fnResp["callId"]))
+				}
+				if callID == "" {
+					callID = strings.TrimSpace(asString(fnResp["tool_call_id"]))
+				}
+				if callID == "" {
+					callID = "call_gemini"
+				}
+				content := fnResp["response"]
+				if content == nil {
+					content = fnResp["output"]
+				}
+				if content == nil {
+					content = ""
+				}
+				msg := map[string]any{
+					"role":         "tool",
+					"tool_call_id": callID,
+					"content":      content,
+				}
+				if name != "" {
+					msg["name"] = name
+				}
+				out = append(out, msg)
+			}
+		}
+		flushText()
+	}
+	return out
+}
+
+func normalizeGeminiSystemInstruction(raw any) string {
+	switch v := raw.(type) {
+	case string:
+		return strings.TrimSpace(v)
+	case map[string]any:
+		if parts, ok := v["parts"].([]any); ok {
+			texts := make([]string, 0, len(parts))
+			for _, item := range parts {
+				part, ok := item.(map[string]any)
+				if !ok {
+					continue
+				}
+				if text := strings.TrimSpace(asString(part["text"])); text != "" {
+					texts = append(texts, text)
+				}
+			}
+			return strings.Join(texts, "\n")
+		}
+		if text := strings.TrimSpace(asString(v["text"])); text != "" {
+			return text
+		}
+	}
+	return ""
+}
+
+func mapGeminiRole(v any) string {
+	switch strings.ToLower(strings.TrimSpace(asString(v))) {
+	case "user":
+		return "user"
+	case "model", "assistant":
+		return "assistant"
+	case "system":
+		return "system"
+	default:
+		return ""
+	}
+}
+
+func convertGeminiTools(raw any) []any {
+	tools, _ := raw.([]any)
+	if len(tools) == 0 {
+		return nil
+	}
+	out := make([]any, 0, len(tools))
+	for _, item := range tools {
+		tool, ok := item.(map[string]any)
+		if !ok {
+			continue
+		}
+
+		if fnDecls, ok := tool["functionDeclarations"].([]any); ok && len(fnDecls) > 0 {
+			for _, declRaw := range fnDecls {
+				decl, ok := declRaw.(map[string]any)
+				if !ok {
+					continue
+				}
+				name := strings.TrimSpace(asString(decl["name"]))
+				if name == "" {
+					continue
+				}
+				function := map[string]any{
+					"name": name,
+				}
+				if desc := strings.TrimSpace(asString(decl["description"])); desc != "" {
+					function["description"] = desc
+				}
+				if params, ok := decl["parameters"].(map[string]any); ok {
+					function["parameters"] = params
+				}
+				out = append(out, map[string]any{
+					"type":     "function",
+					"function": function,
+				})
+			}
+			continue
+		}
+
+		// OpenAI-style passthrough fallback.
+		if _, ok := tool["function"].(map[string]any); ok {
+			out = append(out, tool)
+			continue
+		}
+
+		// Loose fallback for flattened function schema objects.
+		name := strings.TrimSpace(asString(tool["name"]))
+		if name == "" {
+			continue
+		}
+		fn := map[string]any{"name": name}
+		if desc := strings.TrimSpace(asString(tool["description"])); desc != "" {
+			fn["description"] = desc
+		}
+		if params, ok := tool["parameters"].(map[string]any); ok {
+			fn["parameters"] = params
+		}
+		out = append(out, map[string]any{
+			"type":     "function",
+			"function": fn,
+		})
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
+func collectGeminiPassThrough(req map[string]any) map[string]any {
+	cfg, _ := req["generationConfig"].(map[string]any)
+	if len(cfg) == 0 {
+		return nil
+	}
+	out := map[string]any{}
+	if v, ok := cfg["temperature"]; ok {
+		out["temperature"] = v
+	}
+	if v, ok := cfg["topP"]; ok {
+		out["top_p"] = v
+	}
+	if v, ok := cfg["maxOutputTokens"]; ok {
+		out["max_tokens"] = v
+	}
+	if v, ok := cfg["stopSequences"]; ok {
+		out["stop"] = v
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
+func asString(v any) string {
+	s, _ := v.(string)
+	return s
+}
+
+func stringifyJSON(v any) string {
+	switch x := v.(type) {
+	case nil:
+		return "{}"
+	case string:
+		s := strings.TrimSpace(x)
+		if s == "" {
+			return "{}"
+		}
+		return s
+	default:
+		b, err := json.Marshal(x)
+		if err != nil || len(b) == 0 {
+			return "{}"
+		}
+		return string(b)
+	}
+}

internal/adapter/gemini/deps.go

@@ -0,0 +1,29 @@
+package gemini
+
+import (
+	"context"
+	"net/http"
+
+	"ds2api/internal/auth"
+	"ds2api/internal/config"
+	"ds2api/internal/deepseek"
+)
+
+type AuthResolver interface {
+	Determine(req *http.Request) (*auth.RequestAuth, error)
+	Release(a *auth.RequestAuth)
+}
+
+type DeepSeekCaller interface {
+	CreateSession(ctx context.Context, a *auth.RequestAuth, maxAttempts int) (string, error)
+	GetPow(ctx context.Context, a *auth.RequestAuth, maxAttempts int) (string, error)
+	CallCompletion(ctx context.Context, a *auth.RequestAuth, payload map[string]any, powResp string, maxAttempts int) (*http.Response, error)
+}
+
+type ConfigReader interface {
+	ModelAliases() map[string]string
+}
+
+var _ AuthResolver = (*auth.Resolver)(nil)
+var _ DeepSeekCaller = (*deepseek.Client)(nil)
+var _ ConfigReader = (*config.Store)(nil)

internal/adapter/gemini/handler.go

@@ -0,0 +1,348 @@
+package gemini
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+
+	"ds2api/internal/auth"
+	"ds2api/internal/deepseek"
+	"ds2api/internal/sse"
+	streamengine "ds2api/internal/stream"
+	"ds2api/internal/util"
+)
+
+var writeJSON = util.WriteJSON
+
+type Handler struct {
+	Store ConfigReader
+	Auth  AuthResolver
+	DS    DeepSeekCaller
+}
+
+func RegisterRoutes(r chi.Router, h *Handler) {
+	r.Post("/v1beta/models/{model}:generateContent", h.GenerateContent)
+	r.Post("/v1beta/models/{model}:streamGenerateContent", h.StreamGenerateContent)
+	r.Post("/v1/models/{model}:generateContent", h.GenerateContent)
+	r.Post("/v1/models/{model}:streamGenerateContent", h.StreamGenerateContent)
+}
+
+func (h *Handler) GenerateContent(w http.ResponseWriter, r *http.Request) {
+	h.handleGenerateContent(w, r, false)
+}
+
+func (h *Handler) StreamGenerateContent(w http.ResponseWriter, r *http.Request) {
+	h.handleGenerateContent(w, r, true)
+}
+
+func (h *Handler) handleGenerateContent(w http.ResponseWriter, r *http.Request, stream bool) {
+	a, err := h.Auth.Determine(r)
+	if err != nil {
+		status := http.StatusUnauthorized
+		detail := err.Error()
+		if err == auth.ErrNoAccount {
+			status = http.StatusTooManyRequests
+		}
+		writeGeminiError(w, status, detail)
+		return
+	}
+	defer h.Auth.Release(a)
+
+	var req map[string]any
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeGeminiError(w, http.StatusBadRequest, "invalid json")
+		return
+	}
+
+	routeModel := strings.TrimSpace(chi.URLParam(r, "model"))
+	stdReq, err := normalizeGeminiRequest(h.Store, routeModel, req, stream)
+	if err != nil {
+		writeGeminiError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	sessionID, err := h.DS.CreateSession(r.Context(), a, 3)
+	if err != nil {
+		if a.UseConfigToken {
+			writeGeminiError(w, http.StatusUnauthorized, "Account token is invalid. Please re-login the account in admin.")
+		} else {
+			writeGeminiError(w, http.StatusUnauthorized, "Invalid token.")
+		}
+		return
+	}
+	pow, err := h.DS.GetPow(r.Context(), a, 3)
+	if err != nil {
+		writeGeminiError(w, http.StatusUnauthorized, "Failed to get PoW (invalid token or unknown error).")
+		return
+	}
+	payload := stdReq.CompletionPayload(sessionID)
+	resp, err := h.DS.CallCompletion(r.Context(), a, payload, pow, 3)
+	if err != nil {
+		writeGeminiError(w, http.StatusInternalServerError, "Failed to get completion.")
+		return
+	}
+
+	if stream {
+		h.handleStreamGenerateContent(w, r, resp, stdReq.ResponseModel, stdReq.FinalPrompt, stdReq.Thinking, stdReq.Search, stdReq.ToolNames)
+		return
+	}
+	h.handleNonStreamGenerateContent(w, resp, stdReq.ResponseModel, stdReq.FinalPrompt, stdReq.Thinking, stdReq.ToolNames)
+}
+
+func (h *Handler) handleNonStreamGenerateContent(w http.ResponseWriter, resp *http.Response, model, finalPrompt string, thinkingEnabled bool, toolNames []string) {
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		writeGeminiError(w, resp.StatusCode, strings.TrimSpace(string(body)))
+		return
+	}
+
+	result := sse.CollectStream(resp, thinkingEnabled, true)
+	writeJSON(w, http.StatusOK, buildGeminiGenerateContentResponse(model, finalPrompt, result.Thinking, result.Text, toolNames))
+}
+
+func (h *Handler) handleStreamGenerateContent(w http.ResponseWriter, r *http.Request, resp *http.Response, model, finalPrompt string, thinkingEnabled, searchEnabled bool, toolNames []string) {
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		writeGeminiError(w, resp.StatusCode, strings.TrimSpace(string(body)))
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache, no-transform")
+	w.Header().Set("Connection", "keep-alive")
+	w.Header().Set("X-Accel-Buffering", "no")
+
+	rc := http.NewResponseController(w)
+	_, canFlush := w.(http.Flusher)
+	runtime := newGeminiStreamRuntime(w, rc, canFlush, model, finalPrompt, thinkingEnabled, searchEnabled, toolNames)
+
+	initialType := "text"
+	if thinkingEnabled {
+		initialType = "thinking"
+	}
+	streamengine.ConsumeSSE(streamengine.ConsumeConfig{
+		Context:             r.Context(),
+		Body:                resp.Body,
+		ThinkingEnabled:     thinkingEnabled,
+		InitialType:         initialType,
+		KeepAliveInterval:   time.Duration(deepseek.KeepAliveTimeout) * time.Second,
+		IdleTimeout:         time.Duration(deepseek.StreamIdleTimeout) * time.Second,
+		MaxKeepAliveNoInput: deepseek.MaxKeepaliveCount,
+	}, streamengine.ConsumeHooks{
+		OnParsed: runtime.onParsed,
+		OnFinalize: func(_ streamengine.StopReason, _ error) {
+			runtime.finalize()
+		},
+	})
+}
+
+func buildGeminiGenerateContentResponse(model, finalPrompt, finalThinking, finalText string, toolNames []string) map[string]any {
+	parts := buildGeminiPartsFromFinal(finalText, finalThinking, toolNames)
+	usage := buildGeminiUsage(finalPrompt, finalThinking, finalText)
+	return map[string]any{
+		"candidates": []map[string]any{
+			{
+				"index": 0,
+				"content": map[string]any{
+					"role":  "model",
+					"parts": parts,
+				},
+				"finishReason": "STOP",
+			},
+		},
+		"modelVersion":  model,
+		"usageMetadata": usage,
+	}
+}
+
+func buildGeminiUsage(finalPrompt, finalThinking, finalText string) map[string]any {
+	promptTokens := util.EstimateTokens(finalPrompt)
+	reasoningTokens := util.EstimateTokens(finalThinking)
+	completionTokens := util.EstimateTokens(finalText)
+	return map[string]any{
+		"promptTokenCount":     promptTokens,
+		"candidatesTokenCount": reasoningTokens + completionTokens,
+		"totalTokenCount":      promptTokens + reasoningTokens + completionTokens,
+	}
+}
+
+func buildGeminiPartsFromFinal(finalText, finalThinking string, toolNames []string) []map[string]any {
+	detected := util.ParseToolCalls(finalText, toolNames)
+	if len(detected) == 0 && strings.TrimSpace(finalThinking) != "" {
+		detected = util.ParseToolCalls(finalThinking, toolNames)
+	}
+	if len(detected) > 0 {
+		parts := make([]map[string]any, 0, len(detected))
+		for _, tc := range detected {
+			parts = append(parts, map[string]any{
+				"functionCall": map[string]any{
+					"name": tc.Name,
+					"args": tc.Input,
+				},
+			})
+		}
+		return parts
+	}
+
+	text := finalText
+	if strings.TrimSpace(text) == "" {
+		text = finalThinking
+	}
+	return []map[string]any{{"text": text}}
+}
+
+type geminiStreamRuntime struct {
+	w        http.ResponseWriter
+	rc       *http.ResponseController
+	canFlush bool
+
+	model       string
+	finalPrompt string
+
+	thinkingEnabled bool
+	searchEnabled   bool
+	bufferContent   bool
+	toolNames       []string
+
+	thinking strings.Builder
+	text     strings.Builder
+}
+
+func newGeminiStreamRuntime(
+	w http.ResponseWriter,
+	rc *http.ResponseController,
+	canFlush bool,
+	model string,
+	finalPrompt string,
+	thinkingEnabled bool,
+	searchEnabled bool,
+	toolNames []string,
+) *geminiStreamRuntime {
+	return &geminiStreamRuntime{
+		w:               w,
+		rc:              rc,
+		canFlush:        canFlush,
+		model:           model,
+		finalPrompt:     finalPrompt,
+		thinkingEnabled: thinkingEnabled,
+		searchEnabled:   searchEnabled,
+		bufferContent:   len(toolNames) > 0,
+		toolNames:       toolNames,
+	}
+}
+
+func (s *geminiStreamRuntime) sendChunk(payload map[string]any) {
+	b, _ := json.Marshal(payload)
+	_, _ = s.w.Write([]byte("data: "))
+	_, _ = s.w.Write(b)
+	_, _ = s.w.Write([]byte("\n\n"))
+	if s.canFlush {
+		_ = s.rc.Flush()
+	}
+}
+
+func (s *geminiStreamRuntime) onParsed(parsed sse.LineResult) streamengine.ParsedDecision {
+	if !parsed.Parsed {
+		return streamengine.ParsedDecision{}
+	}
+	if parsed.ContentFilter || parsed.ErrorMessage != "" || parsed.Stop {
+		return streamengine.ParsedDecision{Stop: true}
+	}
+
+	contentSeen := false
+	for _, p := range parsed.Parts {
+		if p.Text == "" {
+			continue
+		}
+		if p.Type != "thinking" && s.searchEnabled && sse.IsCitation(p.Text) {
+			continue
+		}
+		contentSeen = true
+		if p.Type == "thinking" {
+			if s.thinkingEnabled {
+				s.thinking.WriteString(p.Text)
+			}
+			continue
+		}
+		s.text.WriteString(p.Text)
+		if s.bufferContent {
+			continue
+		}
+		s.sendChunk(map[string]any{
+			"candidates": []map[string]any{
+				{
+					"index": 0,
+					"content": map[string]any{
+						"role":  "model",
+						"parts": []map[string]any{{"text": p.Text}},
+					},
+				},
+			},
+			"modelVersion": s.model,
+		})
+	}
+	return streamengine.ParsedDecision{ContentSeen: contentSeen}
+}
+
+func (s *geminiStreamRuntime) finalize() {
+	finalThinking := s.thinking.String()
+	finalText := s.text.String()
+
+	if s.bufferContent {
+		parts := buildGeminiPartsFromFinal(finalText, finalThinking, s.toolNames)
+		s.sendChunk(map[string]any{
+			"candidates": []map[string]any{
+				{
+					"index": 0,
+					"content": map[string]any{
+						"role":  "model",
+						"parts": parts,
+					},
+				},
+			},
+			"modelVersion": s.model,
+		})
+	}
+
+	s.sendChunk(map[string]any{
+		"candidates": []map[string]any{
+			{
+				"index":        0,
+				"finishReason": "STOP",
+			},
+		},
+		"modelVersion":  s.model,
+		"usageMetadata": buildGeminiUsage(s.finalPrompt, finalThinking, finalText),
+	})
+}
+
+func writeGeminiError(w http.ResponseWriter, status int, message string) {
+	errorStatus := "INVALID_ARGUMENT"
+	switch status {
+	case http.StatusUnauthorized:
+		errorStatus = "UNAUTHENTICATED"
+	case http.StatusForbidden:
+		errorStatus = "PERMISSION_DENIED"
+	case http.StatusTooManyRequests:
+		errorStatus = "RESOURCE_EXHAUSTED"
+	case http.StatusNotFound:
+		errorStatus = "NOT_FOUND"
+	default:
+		if status >= 500 {
+			errorStatus = "INTERNAL"
+		}
+	}
+	writeJSON(w, status, map[string]any{
+		"error": map[string]any{
+			"code":    status,
+			"message": message,
+			"status":  errorStatus,
+		},
+	})
+}

internal/adapter/gemini/handler_test.go

@@ -0,0 +1,174 @@
+package gemini
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"ds2api/internal/auth"
+)
+
+type testGeminiConfig struct{}
+
+func (testGeminiConfig) ModelAliases() map[string]string { return nil }
+
+type testGeminiAuth struct {
+	a   *auth.RequestAuth
+	err error
+}
+
+func (m testGeminiAuth) Determine(_ *http.Request) (*auth.RequestAuth, error) {
+	if m.err != nil {
+		return nil, m.err
+	}
+	if m.a != nil {
+		return m.a, nil
+	}
+	return &auth.RequestAuth{
+		UseConfigToken: false,
+		DeepSeekToken:  "direct-token",
+		CallerID:       "caller:test",
+		TriedAccounts:  map[string]bool{},
+	}, nil
+}
+
+func (testGeminiAuth) Release(_ *auth.RequestAuth) {}
+
+type testGeminiDS struct {
+	resp *http.Response
+	err  error
+}
+
+func (m testGeminiDS) CreateSession(_ context.Context, _ *auth.RequestAuth, _ int) (string, error) {
+	return "session-id", nil
+}
+
+func (m testGeminiDS) GetPow(_ context.Context, _ *auth.RequestAuth, _ int) (string, error) {
+	return "pow", nil
+}
+
+func (m testGeminiDS) CallCompletion(_ context.Context, _ *auth.RequestAuth, _ map[string]any, _ string, _ int) (*http.Response, error) {
+	if m.err != nil {
+		return nil, m.err
+	}
+	return m.resp, nil
+}
+
+func makeGeminiUpstreamResponse(lines ...string) *http.Response {
+	body := strings.Join(lines, "\n")
+	if !strings.HasSuffix(body, "\n") {
+		body += "\n"
+	}
+	return &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     make(http.Header),
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+}
+
+func TestGeminiRoutesRegistered(t *testing.T) {
+	h := &Handler{
+		Store: testGeminiConfig{},
+		Auth:  testGeminiAuth{err: auth.ErrUnauthorized},
+	}
+	r := chi.NewRouter()
+	RegisterRoutes(r, h)
+
+	paths := []string{
+		"/v1beta/models/gemini-2.5-pro:generateContent",
+		"/v1beta/models/gemini-2.5-pro:streamGenerateContent",
+		"/v1/models/gemini-2.5-pro:generateContent",
+		"/v1/models/gemini-2.5-pro:streamGenerateContent",
+	}
+	for _, path := range paths {
+		req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(`{"contents":[{"role":"user","parts":[{"text":"hi"}]}]}`))
+		rec := httptest.NewRecorder()
+		r.ServeHTTP(rec, req)
+		if rec.Code == http.StatusNotFound {
+			t.Fatalf("expected route %s to be registered, got 404", path)
+		}
+	}
+}
+
+func TestGenerateContentReturnsFunctionCallParts(t *testing.T) {
+	upstream := makeGeminiUpstreamResponse(
+		`data: {"p":"response/content","v":"我来调用工具\n{\"tool_calls\":[{\"name\":\"eval_javascript\",\"input\":{\"code\":\"1+1\"}}]}"}`,
+		`data: [DONE]`,
+	)
+	h := &Handler{
+		Store: testGeminiConfig{},
+		Auth:  testGeminiAuth{},
+		DS:    testGeminiDS{resp: upstream},
+	}
+	r := chi.NewRouter()
+	RegisterRoutes(r, h)
+
+	body := `{
+		"contents":[{"role":"user","parts":[{"text":"call tool"}]}],
+		"tools":[{"functionDeclarations":[{"name":"eval_javascript","description":"eval","parameters":{"type":"object","properties":{"code":{"type":"string"}}}}]}]
+	}`
+	req := httptest.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.5-pro:generateContent", strings.NewReader(body))
+	req.Header.Set("Authorization", "Bearer direct-token")
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", rec.Code, rec.Body.String())
+	}
+
+	var out map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+		t.Fatalf("decode response failed: %v", err)
+	}
+	candidates, _ := out["candidates"].([]any)
+	if len(candidates) == 0 {
+		t.Fatalf("expected non-empty candidates: %#v", out)
+	}
+	c0, _ := candidates[0].(map[string]any)
+	content, _ := c0["content"].(map[string]any)
+	parts, _ := content["parts"].([]any)
+	if len(parts) == 0 {
+		t.Fatalf("expected non-empty parts: %#v", content)
+	}
+	part0, _ := parts[0].(map[string]any)
+	functionCall, _ := part0["functionCall"].(map[string]any)
+	if functionCall["name"] != "eval_javascript" {
+		t.Fatalf("expected functionCall name eval_javascript, got %#v", functionCall)
+	}
+}
+
+func TestStreamGenerateContentEmitsSSE(t *testing.T) {
+	upstream := makeGeminiUpstreamResponse(
+		`data: {"p":"response/content","v":"hello "}`,
+		`data: {"p":"response/content","v":"world"}`,
+		`data: [DONE]`,
+	)
+	h := &Handler{
+		Store: testGeminiConfig{},
+		Auth:  testGeminiAuth{},
+		DS:    testGeminiDS{resp: upstream},
+	}
+	r := chi.NewRouter()
+	RegisterRoutes(r, h)
+
+	body := `{"contents":[{"role":"user","parts":[{"text":"hello"}]}]}`
+	req := httptest.NewRequest(http.MethodPost, "/v1/models/gemini-2.5-pro:streamGenerateContent?alt=sse", strings.NewReader(body))
+	req.Header.Set("Authorization", "Bearer direct-token")
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", rec.Code, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "data: ") {
+		t.Fatalf("expected SSE data frames, got body=%s", rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), `"finishReason":"STOP"`) {
+		t.Fatalf("expected stream finish frame, got body=%s", rec.Body.String())
+	}
+}

internal/adapter/openai/handler.go

@@ -154,7 +154,7 @@ func (h *Handler) handleStream(w http.ResponseWriter, r *http.Request, resp *htt
 	w.Header().Set("Connection", "keep-alive")
 	w.Header().Set("X-Accel-Buffering", "no")
 	rc := http.NewResponseController(w)
-	canFlush := rc.Flush() == nil
+	_, canFlush := w.(http.Flusher)
 	if !canFlush {
 		config.Logger.Warn("[stream] response writer does not support flush; streaming may be buffered")
 	}

internal/adapter/openai/prompt_build.go

@@ -12,3 +12,10 @@ func buildOpenAIFinalPrompt(messagesRaw []any, toolsRaw any, traceID string) (st
 	}
 	return deepseek.MessagesPrepare(messages), toolNames
 }
+
+// BuildPromptForAdapter exposes the OpenAI-compatible prompt building flow so
+// other protocol adapters (for example Gemini) can reuse the same tool/history
+// normalization logic and remain behavior-compatible with chat/completions.
+func BuildPromptForAdapter(messagesRaw []any, toolsRaw any, traceID string) (string, []string) {
+	return buildOpenAIFinalPrompt(messagesRaw, toolsRaw, traceID)
+}

internal/adapter/openai/responses_handler.go

@@ -128,7 +128,7 @@ func (h *Handler) handleResponsesStream(w http.ResponseWriter, r *http.Request,
 	w.Header().Set("Connection", "keep-alive")
 	w.Header().Set("X-Accel-Buffering", "no")
 	rc := http.NewResponseController(w)
-	canFlush := rc.Flush() == nil
+	_, canFlush := w.(http.Flusher)
 
 	initialType := "text"
 	if thinkingEnabled {

internal/adapter/openai/responses_stream_runtime.go

@@ -114,13 +114,7 @@ func (s *responsesStreamRuntime) finalize() {
 	// Compatibility fallback: some streams only emit incremental tool deltas.
 	// Ensure final function_call_arguments.done is emitted at least once.
 	if s.toolCallsEmitted {
-		detected := util.ParseStandaloneToolCalls(finalText, s.toolNames)
-		if len(detected) == 0 {
-			detected = util.ParseToolCalls(finalText, s.toolNames)
-		}
-		if len(detected) == 0 {
-			detected = util.ParseStandaloneToolCalls(finalThinking, s.toolNames)
-		}
+		detected := util.ParseToolCalls(finalText, s.toolNames)
 		if len(detected) == 0 {
 			detected = util.ParseToolCalls(finalThinking, s.toolNames)
 		}

internal/adapter/openai/responses_stream_test.go

@@ -381,6 +381,48 @@ func TestHandleResponsesStreamMultiToolCallFromThinkingChannel(t *testing.T) {
 	}
 }
 
+func TestHandleResponsesStreamCompletedFollowsChatToolCallSemantics(t *testing.T) {
+	h := &Handler{}
+	req := httptest.NewRequest(http.MethodPost, "/v1/responses", nil)
+	rec := httptest.NewRecorder()
+
+	sseLine := func(v string) string {
+		b, _ := json.Marshal(map[string]any{
+			"p": "response/content",
+			"v": v,
+		})
+		return "data: " + string(b) + "\n"
+	}
+
+	streamBody := sseLine("我来调用工具\n") +
+		sseLine(`{"tool_calls":[{"name":"read_file","input":{"path":"README.MD"}}]}`) +
+		"data: [DONE]\n"
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Body:       io.NopCloser(strings.NewReader(streamBody)),
+	}
+
+	h.handleResponsesStream(rec, req, resp, "owner-a", "resp_test", "deepseek-chat", "prompt", false, false, []string{"read_file"})
+
+	completed, ok := extractSSEEventPayload(rec.Body.String(), "response.completed")
+	if !ok {
+		t.Fatalf("expected response.completed event, body=%s", rec.Body.String())
+	}
+	responseObj, _ := completed["response"].(map[string]any)
+	output, _ := responseObj["output"].([]any)
+	hasFunctionCall := false
+	for _, item := range output {
+		m, _ := item.(map[string]any)
+		if m != nil && m["type"] == "function_call" {
+			hasFunctionCall = true
+			break
+		}
+	}
+	if !hasFunctionCall {
+		t.Fatalf("expected completed output to include function_call when mixed prose contains tool_calls payload, output=%#v", output)
+	}
+}
+
 func extractSSEEventPayload(body, targetEvent string) (map[string]any, bool) {
 	scanner := bufio.NewScanner(strings.NewReader(body))
 	matched := false

internal/auth/request.go

@@ -187,7 +187,12 @@ func extractCallerToken(req *http.Request) string {
 			return token
 		}
 	}
-	return strings.TrimSpace(req.Header.Get("x-api-key"))
+	if key := strings.TrimSpace(req.Header.Get("x-api-key")); key != "" {
+		return key
+	}
+	// Gemini AI Studio compatibility: allow query key fallback only when no
+	// header-based credential is present.
+	return strings.TrimSpace(req.URL.Query().Get("key"))
 }
 
 func callerTokenID(token string) string {

internal/auth/request_test.go

@@ -114,6 +114,40 @@ func TestDetermineMissingToken(t *testing.T) {
 	}
 }
 
+func TestDetermineWithQueryKeyUsesDirectToken(t *testing.T) {
+	r := newTestResolver(t)
+	req, _ := http.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.5-pro:generateContent?key=direct-query-key", nil)
+
+	a, err := r.Determine(req)
+	if err != nil {
+		t.Fatalf("determine failed: %v", err)
+	}
+	if a.UseConfigToken {
+		t.Fatalf("expected direct token mode")
+	}
+	if a.DeepSeekToken != "direct-query-key" {
+		t.Fatalf("unexpected token: %q", a.DeepSeekToken)
+	}
+}
+
+func TestDetermineHeaderTokenPrecedenceOverQueryKey(t *testing.T) {
+	r := newTestResolver(t)
+	req, _ := http.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.5-pro:generateContent?key=query-key", nil)
+	req.Header.Set("x-api-key", "managed-key")
+
+	a, err := r.Determine(req)
+	if err != nil {
+		t.Fatalf("determine failed: %v", err)
+	}
+	defer r.Release(a)
+	if !a.UseConfigToken {
+		t.Fatalf("expected managed key mode from header token")
+	}
+	if a.AccountID == "" {
+		t.Fatalf("expected managed account to be acquired")
+	}
+}
+
 func TestDetermineCallerMissingToken(t *testing.T) {
 	r := newTestResolver(t)
 	req, _ := http.NewRequest(http.MethodGet, "/v1/responses/resp_1", nil)

internal/format/openai/render.go

@@ -44,12 +44,11 @@ func BuildChatCompletion(completionID, model, finalPrompt, finalThinking, finalT
 }
 
 func BuildResponseObject(responseID, model, finalPrompt, finalThinking, finalText string, toolNames []string) map[string]any {
-	// Responses output should only be treated as tool calls when the model
-	// produced a standalone structured payload. This prevents accidental
-	// empty output_text on normal prose that merely contains tool_call-like text.
-	detected := util.ParseStandaloneToolCalls(finalText, toolNames)
+	// Align responses tool-call semantics with chat/completions:
+	// mixed prose + tool_call payloads should still be interpreted as tool calls.
+	detected := util.ParseToolCalls(finalText, toolNames)
 	if len(detected) == 0 && strings.TrimSpace(finalThinking) != "" {
-		detected = util.ParseStandaloneToolCalls(finalThinking, toolNames)
+		detected = util.ParseToolCalls(finalThinking, toolNames)
 	}
 	exposedOutputText := finalText
 	output := make([]any, 0, 2)

internal/format/openai/render_test.go

@@ -70,7 +70,7 @@ func TestBuildResponseObjectToolCallsFollowChatShape(t *testing.T) {
 	}
 }
 
-func TestBuildResponseObjectKeepsOutputTextForMixedProse(t *testing.T) {
+func TestBuildResponseObjectTreatsMixedProseToolPayloadAsToolCall(t *testing.T) {
 	obj := BuildResponseObject(
 		"resp_test",
 		"gpt-4o",
@@ -81,17 +81,41 @@ func TestBuildResponseObjectKeepsOutputTextForMixedProse(t *testing.T) {
 	)
 
 	outputText, _ := obj["output_text"].(string)
-	if outputText == "" {
-		t.Fatalf("expected output_text to be preserved for mixed prose")
+	if outputText != "" {
+		t.Fatalf("expected output_text hidden once tool calls are detected, got %q", outputText)
 	}
 
+	output, _ := obj["output"].([]any)
+	if len(output) != 2 {
+		t.Fatalf("expected function_call + tool_calls wrapper, got %#v", obj["output"])
+	}
+	first, _ := output[0].(map[string]any)
+	if first["type"] != "function_call" {
+		t.Fatalf("expected first output type function_call, got %#v", first["type"])
+	}
+}
+
+func TestBuildResponseObjectFencedToolPayloadRemainsText(t *testing.T) {
+	obj := BuildResponseObject(
+		"resp_test",
+		"gpt-4o",
+		"prompt",
+		"",
+		"```json\n{\"tool_calls\":[{\"name\":\"search\",\"input\":{\"q\":\"golang\"}}]}\n```",
+		[]string{"search"},
+	)
+
+	outputText, _ := obj["output_text"].(string)
+	if outputText == "" {
+		t.Fatalf("expected output_text preserved for fenced example")
+	}
 	output, _ := obj["output"].([]any)
 	if len(output) != 1 {
-		t.Fatalf("expected one output item, got %#v", obj["output"])
+		t.Fatalf("expected one message output item, got %#v", obj["output"])
 	}
 	first, _ := output[0].(map[string]any)
 	if first["type"] != "message" {
-		t.Fatalf("expected output type message, got %#v", first["type"])
+		t.Fatalf("expected message output type, got %#v", first["type"])
 	}
 }
 

internal/server/router.go

@@ -12,6 +12,7 @@ import (
 
 	"ds2api/internal/account"
 	"ds2api/internal/adapter/claude"
+	"ds2api/internal/adapter/gemini"
 	"ds2api/internal/adapter/openai"
 	"ds2api/internal/admin"
 	"ds2api/internal/auth"
@@ -44,6 +45,7 @@ func NewApp() *App {
 
 	openaiHandler := &openai.Handler{Store: store, Auth: resolver, DS: dsClient}
 	claudeHandler := &claude.Handler{Store: store, Auth: resolver, DS: dsClient}
+	geminiHandler := &gemini.Handler{Store: store, Auth: resolver, DS: dsClient}
 	adminHandler := &admin.Handler{Store: store, Pool: pool, DS: dsClient}
 	webuiHandler := webui.NewHandler()
 
@@ -67,6 +69,7 @@ func NewApp() *App {
 	})
 	openai.RegisterRoutes(r, openaiHandler)
 	claude.RegisterRoutes(r, claudeHandler)
+	gemini.RegisterRoutes(r, geminiHandler)
 	r.Route("/admin", func(ar chi.Router) {
 		admin.RegisterRoutes(ar, adminHandler)
 	})