fix: handle vercel prepare/release passthrough in translated proxy paths

internal/adapter/claude/deps.go

@@ -24,6 +24,10 @@ type ConfigReader interface {
 	ClaudeMapping() map[string]string
 }
 
+type OpenAIChatRunner interface {
+	ChatCompletions(w http.ResponseWriter, r *http.Request)
+}
+
 var _ AuthResolver = (*auth.Resolver)(nil)
 var _ DeepSeekCaller = (*deepseek.Client)(nil)
 var _ ConfigReader = (*config.Store)(nil)

internal/adapter/claude/handler_messages.go

@@ -1,10 +1,12 @@
 package claude
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
+	"net/http/httptest"
 	"strings"
 	"time"
 
@@ -13,12 +15,21 @@ import (
 	claudefmt "ds2api/internal/format/claude"
 	"ds2api/internal/sse"
 	streamengine "ds2api/internal/stream"
+	"ds2api/internal/translatorcliproxy"
+	"ds2api/internal/util"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
 )
 
 func (h *Handler) Messages(w http.ResponseWriter, r *http.Request) {
 	if strings.TrimSpace(r.Header.Get("anthropic-version")) == "" {
 		r.Header.Set("anthropic-version", "2023-06-01")
 	}
+	if h.OpenAI != nil {
+		if h.proxyViaOpenAI(w, r) {
+			return
+		}
+	}
 	a, err := h.Auth.Determine(r)
 	if err != nil {
 		status := http.StatusUnauthorized
@@ -82,6 +93,91 @@ func (h *Handler) Messages(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, respBody)
 }
 
+func (h *Handler) proxyViaOpenAI(w http.ResponseWriter, r *http.Request) bool {
+	raw, err := io.ReadAll(r.Body)
+	if err != nil {
+		writeClaudeError(w, http.StatusBadRequest, "invalid body")
+		return true
+	}
+	var req map[string]any
+	if err := json.Unmarshal(raw, &req); err != nil {
+		writeClaudeError(w, http.StatusBadRequest, "invalid json")
+		return true
+	}
+	model, _ := req["model"].(string)
+	stream := util.ToBool(req["stream"])
+	translatedReq := translatorcliproxy.ToOpenAI(sdktranslator.FormatClaude, model, raw, stream)
+
+	isVercelPrepare := strings.TrimSpace(r.URL.Query().Get("__stream_prepare")) == "1"
+	isVercelRelease := strings.TrimSpace(r.URL.Query().Get("__stream_release")) == "1"
+
+	if isVercelRelease {
+		proxyReq := r.Clone(r.Context())
+		proxyReq.URL.Path = "/v1/chat/completions"
+		proxyReq.Body = io.NopCloser(bytes.NewReader(raw))
+		proxyReq.ContentLength = int64(len(raw))
+		rec := httptest.NewRecorder()
+		h.OpenAI.ChatCompletions(rec, proxyReq)
+		res := rec.Result()
+		defer res.Body.Close()
+		body, _ := io.ReadAll(res.Body)
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+
+	proxyReq := r.Clone(r.Context())
+	proxyReq.URL.Path = "/v1/chat/completions"
+	proxyReq.Body = io.NopCloser(bytes.NewReader(translatedReq))
+	proxyReq.ContentLength = int64(len(translatedReq))
+
+	if stream && !isVercelPrepare {
+		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")
+		streamWriter := translatorcliproxy.NewOpenAIStreamTranslatorWriter(w, sdktranslator.FormatClaude, model, raw, translatedReq)
+		h.OpenAI.ChatCompletions(streamWriter, proxyReq)
+		return true
+	}
+
+	rec := httptest.NewRecorder()
+	h.OpenAI.ChatCompletions(rec, proxyReq)
+	res := rec.Result()
+	defer res.Body.Close()
+	body, _ := io.ReadAll(res.Body)
+	if res.StatusCode < 200 || res.StatusCode >= 300 {
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+	if isVercelPrepare {
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+	converted := translatorcliproxy.FromOpenAINonStream(sdktranslator.FormatClaude, model, raw, translatedReq, body)
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(converted)
+	return true
+}
+
 func (h *Handler) handleClaudeStreamRealtime(w http.ResponseWriter, r *http.Request, resp *http.Response, model string, messages []any, thinkingEnabled, searchEnabled bool, toolNames []string) {
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {

internal/adapter/claude/handler_routes.go

@@ -15,9 +15,10 @@ import (
 var writeJSON = util.WriteJSON
 
 type Handler struct {
-	Store ConfigReader
-	Auth  AuthResolver
-	DS    DeepSeekCaller
+	Store  ConfigReader
+	Auth   AuthResolver
+	DS     DeepSeekCaller
+	OpenAI OpenAIChatRunner
 }
 
 var (

internal/adapter/claude/proxy_vercel_test.go

@@ -0,0 +1,42 @@
+package claude
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+type openAIProxyStub struct {
+	status int
+	body   string
+}
+
+func (s openAIProxyStub) ChatCompletions(w http.ResponseWriter, _ *http.Request) {
+	if s.status == 0 {
+		s.status = http.StatusOK
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(s.status)
+	_, _ = w.Write([]byte(s.body))
+}
+
+func TestClaudeProxyViaOpenAIVercelPreparePassthrough(t *testing.T) {
+	h := &Handler{OpenAI: openAIProxyStub{status: 200, body: `{"lease_id":"lease_123","payload":{"a":1}}`}}
+	req := httptest.NewRequest(http.MethodPost, "/anthropic/v1/messages?__stream_prepare=1", strings.NewReader(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":true}`))
+	rec := httptest.NewRecorder()
+
+	h.Messages(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: %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("expected json response, got err=%v body=%s", err, rec.Body.String())
+	}
+	if _, ok := out["lease_id"]; !ok {
+		t.Fatalf("expected lease_id in prepare passthrough, got=%v", out)
+	}
+}

internal/adapter/gemini/deps.go

@@ -24,6 +24,10 @@ type ConfigReader interface {
 	ModelAliases() map[string]string
 }
 
+type OpenAIChatRunner interface {
+	ChatCompletions(w http.ResponseWriter, r *http.Request)
+}
+
 var _ AuthResolver = (*auth.Resolver)(nil)
 var _ DeepSeekCaller = (*deepseek.Client)(nil)
 var _ ConfigReader = (*config.Store)(nil)

internal/adapter/gemini/handler_generate.go

@@ -1,19 +1,29 @@
 package gemini
 
 import (
+	"bytes"
 	"encoding/json"
 	"io"
 	"net/http"
+	"net/http/httptest"
 	"strings"
 
 	"github.com/go-chi/chi/v5"
 
 	"ds2api/internal/auth"
 	"ds2api/internal/sse"
+	"ds2api/internal/translatorcliproxy"
 	"ds2api/internal/util"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
 )
 
 func (h *Handler) handleGenerateContent(w http.ResponseWriter, r *http.Request, stream bool) {
+	if h.OpenAI != nil {
+		if h.proxyViaOpenAI(w, r, stream) {
+			return
+		}
+	}
 	a, err := h.Auth.Determine(r)
 	if err != nil {
 		status := http.StatusUnauthorized
@@ -67,6 +77,94 @@ func (h *Handler) handleGenerateContent(w http.ResponseWriter, r *http.Request,
 	h.handleNonStreamGenerateContent(w, resp, stdReq.ResponseModel, stdReq.FinalPrompt, stdReq.Thinking, stdReq.ToolNames)
 }
 
+func (h *Handler) proxyViaOpenAI(w http.ResponseWriter, r *http.Request, stream bool) bool {
+	raw, err := io.ReadAll(r.Body)
+	if err != nil {
+		writeGeminiError(w, http.StatusBadRequest, "invalid body")
+		return true
+	}
+	routeModel := strings.TrimSpace(chi.URLParam(r, "model"))
+	translatedReq := translatorcliproxy.ToOpenAI(sdktranslator.FormatGemini, routeModel, raw, stream)
+	if !strings.Contains(string(translatedReq), `"stream"`) {
+		var reqMap map[string]any
+		if json.Unmarshal(translatedReq, &reqMap) == nil {
+			reqMap["stream"] = stream
+			if b, e := json.Marshal(reqMap); e == nil {
+				translatedReq = b
+			}
+		}
+	}
+
+	isVercelPrepare := strings.TrimSpace(r.URL.Query().Get("__stream_prepare")) == "1"
+	isVercelRelease := strings.TrimSpace(r.URL.Query().Get("__stream_release")) == "1"
+
+	if isVercelRelease {
+		proxyReq := r.Clone(r.Context())
+		proxyReq.URL.Path = "/v1/chat/completions"
+		proxyReq.Body = io.NopCloser(bytes.NewReader(raw))
+		proxyReq.ContentLength = int64(len(raw))
+		rec := httptest.NewRecorder()
+		h.OpenAI.ChatCompletions(rec, proxyReq)
+		res := rec.Result()
+		defer res.Body.Close()
+		body, _ := io.ReadAll(res.Body)
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+
+	proxyReq := r.Clone(r.Context())
+	proxyReq.URL.Path = "/v1/chat/completions"
+	proxyReq.Body = io.NopCloser(bytes.NewReader(translatedReq))
+	proxyReq.ContentLength = int64(len(translatedReq))
+
+	if stream && !isVercelPrepare {
+		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")
+		streamWriter := translatorcliproxy.NewOpenAIStreamTranslatorWriter(w, sdktranslator.FormatGemini, routeModel, raw, translatedReq)
+		h.OpenAI.ChatCompletions(streamWriter, proxyReq)
+		return true
+	}
+
+	rec := httptest.NewRecorder()
+	h.OpenAI.ChatCompletions(rec, proxyReq)
+	res := rec.Result()
+	defer res.Body.Close()
+	body, _ := io.ReadAll(res.Body)
+	if res.StatusCode < 200 || res.StatusCode >= 300 {
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+	if isVercelPrepare {
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(res.StatusCode)
+		_, _ = w.Write(body)
+		return true
+	}
+	converted := translatorcliproxy.FromOpenAINonStream(sdktranslator.FormatGemini, routeModel, raw, translatedReq, body)
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(converted)
+	return true
+}
+
 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 {

internal/adapter/gemini/handler_routes.go

@@ -11,9 +11,10 @@ import (
 var writeJSON = util.WriteJSON
 
 type Handler struct {
-	Store ConfigReader
-	Auth  AuthResolver
-	DS    DeepSeekCaller
+	Store  ConfigReader
+	Auth   AuthResolver
+	DS     DeepSeekCaller
+	OpenAI OpenAIChatRunner
 }
 
 func RegisterRoutes(r chi.Router, h *Handler) {

internal/adapter/gemini/proxy_vercel_test.go

@@ -0,0 +1,42 @@
+package gemini
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+type openAIProxyStub struct {
+	status int
+	body   string
+}
+
+func (s openAIProxyStub) ChatCompletions(w http.ResponseWriter, _ *http.Request) {
+	if s.status == 0 {
+		s.status = http.StatusOK
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(s.status)
+	_, _ = w.Write([]byte(s.body))
+}
+
+func TestGeminiProxyViaOpenAIVercelReleasePassthrough(t *testing.T) {
+	h := &Handler{OpenAI: openAIProxyStub{status: 200, body: `{"success":true}`}}
+	req := httptest.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.5-pro:streamGenerateContent?__stream_release=1", strings.NewReader(`{"lease_id":"lease_123"}`))
+	rec := httptest.NewRecorder()
+
+	h.StreamGenerateContent(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status: %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("expected json response, got err=%v body=%s", err, rec.Body.String())
+	}
+	if v, ok := out["success"].(bool); !ok || !v {
+		t.Fatalf("expected success=true passthrough, got=%v", out)
+	}
+}

internal/server/router.go

@@ -44,8 +44,8 @@ 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}
+	claudeHandler := &claude.Handler{Store: store, Auth: resolver, DS: dsClient, OpenAI: openaiHandler}
+	geminiHandler := &gemini.Handler{Store: store, Auth: resolver, DS: dsClient, OpenAI: openaiHandler}
 	adminHandler := &admin.Handler{Store: store, Pool: pool, DS: dsClient}
 	webuiHandler := webui.NewHandler()
 

internal/translatorcliproxy/bridge.go

@@ -0,0 +1,67 @@
+package translatorcliproxy
+
+import (
+	"bytes"
+	"context"
+	"strings"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+	_ "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator/builtin"
+)
+
+func ToOpenAI(from sdktranslator.Format, model string, raw []byte, stream bool) []byte {
+	return sdktranslator.TranslateRequest(from, sdktranslator.FormatOpenAI, model, raw, stream)
+}
+
+func FromOpenAINonStream(to sdktranslator.Format, model string, originalReq, translatedReq, raw []byte) []byte {
+	var param any
+	return sdktranslator.TranslateNonStream(context.Background(), sdktranslator.FormatOpenAI, to, model, originalReq, translatedReq, raw, &param)
+}
+
+func FromOpenAIStream(to sdktranslator.Format, model string, originalReq, translatedReq, streamBody []byte) []byte {
+	var out bytes.Buffer
+	var param any
+	for _, line := range bytes.Split(streamBody, []byte("\n")) {
+		trimmed := strings.TrimSpace(string(line))
+		if trimmed == "" {
+			continue
+		}
+		payload := append([]byte(nil), line...)
+		if !bytes.HasPrefix(payload, []byte("data:")) {
+			continue
+		}
+		chunks := sdktranslator.TranslateStream(context.Background(), sdktranslator.FormatOpenAI, to, model, originalReq, translatedReq, payload, &param)
+		for i := range chunks {
+			out.Write(chunks[i])
+			if !bytes.HasSuffix(chunks[i], []byte("\n")) {
+				out.WriteByte('\n')
+			}
+		}
+	}
+	return out.Bytes()
+}
+
+func ParseFormat(name string) sdktranslator.Format {
+	switch strings.ToLower(strings.TrimSpace(name)) {
+	case "openai", "openai-chat", "chat", "chat-completions":
+		return sdktranslator.FormatOpenAI
+	case "openai-response", "responses", "openai-responses":
+		return sdktranslator.FormatOpenAIResponse
+	case "claude", "anthropic":
+		return sdktranslator.FormatClaude
+	case "gemini", "google":
+		return sdktranslator.FormatGemini
+	case "gemini-cli", "geminicli":
+		return sdktranslator.FormatGeminiCLI
+	case "codex", "openai-codex":
+		return sdktranslator.FormatCodex
+	case "antigravity":
+		return sdktranslator.FormatAntigravity
+	default:
+		return sdktranslator.FromString(name)
+	}
+}
+
+func ToOpenAIByName(formatName, model string, raw []byte, stream bool) []byte {
+	return ToOpenAI(ParseFormat(formatName), model, raw, stream)
+}

internal/translatorcliproxy/bridge_test.go

@@ -0,0 +1,72 @@
+package translatorcliproxy
+
+import (
+	"strings"
+	"testing"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+)
+
+func TestToOpenAIClaude(t *testing.T) {
+	raw := []byte(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":false}`)
+	got := ToOpenAI(sdktranslator.FormatClaude, "claude-sonnet-4-5", raw, false)
+	s := string(got)
+	if !strings.Contains(s, `"messages"`) || !strings.Contains(s, `"model"`) {
+		t.Fatalf("unexpected translated request: %s", s)
+	}
+}
+
+func TestFromOpenAINonStreamClaude(t *testing.T) {
+	original := []byte(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":false}`)
+	translatedReq := []byte(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":false}`)
+	openaibody := []byte(`{"id":"chatcmpl_1","object":"chat.completion","created":1,"model":"claude-sonnet-4-5","choices":[{"index":0,"message":{"role":"assistant","content":"hello"},"finish_reason":"stop"}],"usage":{"prompt_tokens":1,"completion_tokens":1,"total_tokens":2}}`)
+	got := FromOpenAINonStream(sdktranslator.FormatClaude, "claude-sonnet-4-5", original, translatedReq, openaibody)
+	if !strings.Contains(string(got), `"type":"message"`) {
+		t.Fatalf("expected claude response format, got: %s", string(got))
+	}
+}
+
+func TestParseFormatAliases(t *testing.T) {
+	cases := map[string]sdktranslator.Format{
+		"responses":        sdktranslator.FormatOpenAIResponse,
+		"anthropic":        sdktranslator.FormatClaude,
+		"geminicli":        sdktranslator.FormatGeminiCLI,
+		"openai-codex":     sdktranslator.FormatCodex,
+		"antigravity":      sdktranslator.FormatAntigravity,
+		"chat-completions": sdktranslator.FormatOpenAI,
+	}
+	for in, want := range cases {
+		if got := ParseFormat(in); got != want {
+			t.Fatalf("ParseFormat(%q)=%q want %q", in, got, want)
+		}
+	}
+}
+
+func TestToOpenAIByNameAllSupportedFormats(t *testing.T) {
+	tests := []struct {
+		name   string
+		format string
+		model  string
+		body   string
+	}{
+		{name: "openai", format: "openai", model: "gpt-4.1", body: `{"model":"gpt-4.1","messages":[{"role":"user","content":"hi"}],"stream":false}`},
+		{name: "responses", format: "responses", model: "gpt-4.1", body: `{"model":"gpt-4.1","input":"hello","stream":false}`},
+		{name: "claude", format: "claude", model: "claude-sonnet-4-5", body: `{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hello"}],"stream":false}`},
+		{name: "gemini", format: "gemini", model: "gemini-2.5-pro", body: `{"contents":[{"role":"user","parts":[{"text":"hello"}]}]}`},
+		{name: "gemini-cli", format: "gemini-cli", model: "gemini-2.5-pro", body: `{"model":"gemini-2.5-pro","messages":[{"role":"user","content":"hello"}],"stream":false}`},
+		{name: "codex", format: "codex", model: "gpt-5-codex", body: `{"model":"gpt-5-codex","messages":[{"role":"user","content":"hello"}],"stream":false}`},
+		{name: "antigravity", format: "antigravity", model: "gpt-4.1", body: `{"model":"gpt-4.1","messages":[{"role":"user","content":"hello"}],"stream":false}`},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ToOpenAIByName(tc.format, tc.model, []byte(tc.body), false)
+			if len(got) == 0 {
+				t.Fatalf("expected non-empty conversion result for format=%s", tc.format)
+			}
+			if !strings.Contains(string(got), `"model"`) {
+				t.Fatalf("expected model field in converted payload, got=%s", string(got))
+			}
+		})
+	}
+}

internal/translatorcliproxy/stream_writer.go

@@ -0,0 +1,108 @@
+package translatorcliproxy
+
+import (
+	"bytes"
+	"context"
+	"net/http"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+)
+
+// OpenAIStreamTranslatorWriter translates OpenAI SSE output to another client format in real-time.
+type OpenAIStreamTranslatorWriter struct {
+	dst           http.ResponseWriter
+	target        sdktranslator.Format
+	model         string
+	originalReq   []byte
+	translatedReq []byte
+	param         any
+	statusCode    int
+	headersSent   bool
+	lineBuf       bytes.Buffer
+}
+
+func NewOpenAIStreamTranslatorWriter(dst http.ResponseWriter, target sdktranslator.Format, model string, originalReq, translatedReq []byte) *OpenAIStreamTranslatorWriter {
+	return &OpenAIStreamTranslatorWriter{
+		dst:           dst,
+		target:        target,
+		model:         model,
+		originalReq:   originalReq,
+		translatedReq: translatedReq,
+		statusCode:    http.StatusOK,
+	}
+}
+
+func (w *OpenAIStreamTranslatorWriter) Header() http.Header {
+	return w.dst.Header()
+}
+
+func (w *OpenAIStreamTranslatorWriter) WriteHeader(statusCode int) {
+	if w.headersSent {
+		return
+	}
+	w.statusCode = statusCode
+	w.headersSent = true
+	w.dst.WriteHeader(statusCode)
+}
+
+func (w *OpenAIStreamTranslatorWriter) Write(p []byte) (int, error) {
+	if !w.headersSent {
+		w.WriteHeader(http.StatusOK)
+	}
+	if w.statusCode < 200 || w.statusCode >= 300 {
+		return w.dst.Write(p)
+	}
+	w.lineBuf.Write(p)
+	for {
+		line, ok := w.readOneLine()
+		if !ok {
+			break
+		}
+		trimmed := bytes.TrimSpace(line)
+		if len(trimmed) == 0 {
+			continue
+		}
+		if !bytes.HasPrefix(trimmed, []byte("data:")) {
+			continue
+		}
+		chunks := sdktranslator.TranslateStream(context.Background(), sdktranslator.FormatOpenAI, w.target, w.model, w.originalReq, w.translatedReq, trimmed, &w.param)
+		for i := range chunks {
+			if len(chunks[i]) == 0 {
+				continue
+			}
+			if _, err := w.dst.Write(chunks[i]); err != nil {
+				return len(p), err
+			}
+			if !bytes.HasSuffix(chunks[i], []byte("\n")) {
+				if _, err := w.dst.Write([]byte("\n")); err != nil {
+					return len(p), err
+				}
+			}
+		}
+		if f, ok := w.dst.(http.Flusher); ok {
+			f.Flush()
+		}
+	}
+	return len(p), nil
+}
+
+func (w *OpenAIStreamTranslatorWriter) Flush() {
+	if f, ok := w.dst.(http.Flusher); ok {
+		f.Flush()
+	}
+}
+
+func (w *OpenAIStreamTranslatorWriter) Unwrap() http.ResponseWriter {
+	return w.dst
+}
+
+func (w *OpenAIStreamTranslatorWriter) readOneLine() ([]byte, bool) {
+	b := w.lineBuf.Bytes()
+	idx := bytes.IndexByte(b, '\n')
+	if idx < 0 {
+		return nil, false
+	}
+	line := append([]byte(nil), b[:idx]...)
+	w.lineBuf.Next(idx + 1)
+	return line, true
+}

internal/translatorcliproxy/stream_writer_test.go

@@ -0,0 +1,44 @@
+package translatorcliproxy
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+)
+
+func TestOpenAIStreamTranslatorWriterClaude(t *testing.T) {
+	original := []byte(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":true}`)
+	translated := []byte(`{"model":"claude-sonnet-4-5","messages":[{"role":"user","content":"hi"}],"stream":true}`)
+
+	rec := httptest.NewRecorder()
+	w := NewOpenAIStreamTranslatorWriter(rec, sdktranslator.FormatClaude, "claude-sonnet-4-5", original, translated)
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.WriteHeader(200)
+	_, _ = w.Write([]byte("data: {\"id\":\"chatcmpl_1\",\"object\":\"chat.completion.chunk\",\"created\":1,\"model\":\"claude-sonnet-4-5\",\"choices\":[{\"index\":0,\"delta\":{\"role\":\"assistant\"},\"finish_reason\":null}]}\n\n"))
+	_, _ = w.Write([]byte("data: {\"id\":\"chatcmpl_1\",\"object\":\"chat.completion.chunk\",\"created\":1,\"model\":\"claude-sonnet-4-5\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"hi\"},\"finish_reason\":null}]}\n\n"))
+	_, _ = w.Write([]byte("data: [DONE]\n\n"))
+
+	body := rec.Body.String()
+	if !strings.Contains(body, "event: message_start") {
+		t.Fatalf("expected claude message_start event, got: %s", body)
+	}
+}
+
+func TestOpenAIStreamTranslatorWriterGemini(t *testing.T) {
+	original := []byte(`{"contents":[{"role":"user","parts":[{"text":"hi"}]}]}`)
+	translated := []byte(`{"model":"gemini-2.5-pro","messages":[{"role":"user","content":"hi"}],"stream":true}`)
+
+	rec := httptest.NewRecorder()
+	w := NewOpenAIStreamTranslatorWriter(rec, sdktranslator.FormatGemini, "gemini-2.5-pro", original, translated)
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.WriteHeader(200)
+	_, _ = w.Write([]byte("data: {\"id\":\"chatcmpl_1\",\"object\":\"chat.completion.chunk\",\"created\":1,\"model\":\"gemini-2.5-pro\",\"choices\":[{\"index\":0,\"delta\":{\"content\":\"hi\"},\"finish_reason\":null}]}\n\n"))
+	_, _ = w.Write([]byte("data: [DONE]\n\n"))
+
+	body := rec.Body.String()
+	if !strings.Contains(body, "candidates") {
+		t.Fatalf("expected gemini stream payload, got: %s", body)
+	}
+}