fix: 保留 remote_compaction_v2 原生 Responses 链路

backend/internal/handler/openai_gateway_compact_body_signal_test.go

@@ -23,46 +23,61 @@ func newCompactBodySignalTestContext(t *testing.T, path string, body []byte) *gi
 	return c
 }
 
-// body-signal 提升后必须与 path-based compact 走同一条链路：
-// path 改写、requireCompact 判定、stream/store/prompt_cache_key 归一化删除。
-// 回归防护：若 stream 字段存活，Forward 会用流式 handler 解析 compact 的
-// JSON 响应，导致 "stream ended before a terminal event" 的换号 failover 风暴。
-func TestNormalizeOpenAIResponsesCompactRequest_BodySignalPromoted(t *testing.T) {
+func TestNormalizeOpenAIResponsesCompactRequest_RemoteV2StaysOnResponses(t *testing.T) {
 	h := &OpenAIGatewayHandler{}
 	body := []byte(`{
-		"model":"gpt-5.5",
+		"model":"gpt-5.6-sol",
 		"stream":true,
 		"store":true,
 		"prompt_cache_key":"pck-signal-1",
+		"reasoning":{"effort":"max","context":"all_turns"},
 		"input":[
 			{"type":"message","role":"user","content":"hello"},
 			{"type":"compaction_trigger"}
 		]
 	}`)
 	c := newCompactBodySignalTestContext(t, "/v1/responses", body)
+	c.Request.Header.Set("x-codex-beta-features", "responses_websockets_v2, remote_compaction_v2, another_feature")
 
 	normalized, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), body)
 	require.True(t, ok)
 
-	require.Equal(t, "/v1/responses/compact", c.Request.URL.Path)
-	require.True(t, isOpenAIRemoteCompactPath(c))
-
-	require.False(t, gjson.GetBytes(normalized, "stream").Exists())
-	require.False(t, gjson.GetBytes(normalized, "store").Exists())
-	require.False(t, gjson.GetBytes(normalized, "prompt_cache_key").Exists())
-	require.Equal(t, "gpt-5.5", gjson.GetBytes(normalized, "model").String())
-	require.True(t, gjson.GetBytes(normalized, "input").IsArray())
+	require.Equal(t, "/v1/responses", c.Request.URL.Path)
+	require.False(t, isOpenAIRemoteCompactPath(c))
+	require.Equal(t, body, normalized)
+	require.True(t, gjson.GetBytes(normalized, "stream").Bool())
+	require.True(t, gjson.GetBytes(normalized, "store").Bool())
+	require.Equal(t, "pck-signal-1", gjson.GetBytes(normalized, "prompt_cache_key").String())
+	require.Equal(t, "max", gjson.GetBytes(normalized, "reasoning.effort").String())
+	require.Equal(t, "all_turns", gjson.GetBytes(normalized, "reasoning.context").String())
 
 	reqStream, streamOK := parseOpenAICompatibleStream(normalized)
 	require.True(t, streamOK)
-	require.False(t, reqStream)
+	require.True(t, reqStream)
 
-	seed, exists := c.Get(service.OpenAICompactSessionSeedKeyForTest())
-	require.True(t, exists)
-	require.Equal(t, "pck-signal-1", seed)
+	_, seedExists := c.Get(service.OpenAICompactSessionSeedKeyForTest())
+	require.False(t, seedExists)
+	_, streamMarkerExists := c.Get(service.OpenAICompactClientStreamKeyForTest())
+	require.False(t, streamMarkerExists)
 }
 
-func TestNormalizeOpenAIResponsesCompactRequest_BodySignalTrailingSlash(t *testing.T) {
+func TestNormalizeOpenAIResponsesCompactRequest_RemoteV2PathAliasesStayOnResponses(t *testing.T) {
+	h := &OpenAIGatewayHandler{}
+	body := []byte(`{"model":"gpt-5.6-sol","stream":true,"input":[{"type":"compaction_trigger"}]}`)
+	for _, path := range []string{"/v1/responses/", "/backend-api/codex/responses"} {
+		t.Run(path, func(t *testing.T) {
+			c := newCompactBodySignalTestContext(t, path, body)
+			c.Request.Header.Set("x-codex-beta-features", "remote_compaction_v2")
+
+			normalized, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), body)
+			require.True(t, ok)
+			require.Equal(t, path, c.Request.URL.Path)
+			require.Equal(t, body, normalized)
+		})
+	}
+}
+
+func TestNormalizeOpenAIResponsesCompactRequest_BodySignalTrailingSlashPromoted(t *testing.T) {
 	h := &OpenAIGatewayHandler{}
 	body := []byte(`{"model":"gpt-5.5","input":[{"type":"compaction_trigger"}]}`)
 	c := newCompactBodySignalTestContext(t, "/v1/responses/", body)
@@ -82,6 +97,64 @@ func TestNormalizeOpenAIResponsesCompactRequest_CodexDirectAliasPromoted(t *test
 	require.Equal(t, "/backend-api/codex/responses/compact", c.Request.URL.Path)
 }
 
+func TestNormalizeOpenAIResponsesCompactRequest_NonRemoteV2BodySignalPromoted(t *testing.T) {
+	h := &OpenAIGatewayHandler{}
+	tests := []struct {
+		name       string
+		body       []byte
+		betaHeader string
+		wantMarked bool
+	}{
+		{
+			name:       "no_header",
+			body:       []byte(`{"model":"gpt-5.5","stream":true,"input":[{"type":"compaction_trigger"}]}`),
+			wantMarked: true,
+		},
+		{
+			name:       "unrelated_header",
+			body:       []byte(`{"model":"gpt-5.5","stream":true,"input":[{"type":"compaction_trigger"}]}`),
+			betaHeader: "responses_websockets_v2",
+			wantMarked: true,
+		},
+		{
+			name:       "wrong_case_header",
+			body:       []byte(`{"model":"gpt-5.5","stream":true,"input":[{"type":"compaction_trigger"}]}`),
+			betaHeader: "REMOTE_COMPACTION_V2",
+			wantMarked: true,
+		},
+		{
+			name:       "stream_false",
+			body:       []byte(`{"model":"gpt-5.5","stream":false,"input":[{"type":"compaction_trigger"}]}`),
+			betaHeader: "remote_compaction_v2",
+		},
+		{
+			name:       "stream_absent",
+			body:       []byte(`{"model":"gpt-5.5","input":[{"type":"compaction_trigger"}]}`),
+			betaHeader: "remote_compaction_v2",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := newCompactBodySignalTestContext(t, "/v1/responses", tt.body)
+			if tt.betaHeader != "" {
+				c.Request.Header.Set("x-codex-beta-features", tt.betaHeader)
+			}
+
+			normalized, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), tt.body)
+			require.True(t, ok)
+			require.Equal(t, "/v1/responses/compact", c.Request.URL.Path)
+			require.False(t, gjson.GetBytes(normalized, "stream").Exists())
+
+			marked, exists := c.Get(service.OpenAICompactClientStreamKeyForTest())
+			require.Equal(t, tt.wantMarked, exists)
+			if tt.wantMarked {
+				require.Equal(t, true, marked)
+			}
+		})
+	}
+}
+
 func TestNormalizeOpenAIResponsesCompactRequest_NoTriggerUntouched(t *testing.T) {
 	h := &OpenAIGatewayHandler{}
 	body := []byte(`{"model":"gpt-5.5","stream":true,"input":[{"type":"message","role":"user","content":"hello"}]}`)
@@ -99,6 +172,7 @@ func TestNormalizeOpenAIResponsesCompactRequest_PathBasedNoDoubleSuffix(t *testi
 	h := &OpenAIGatewayHandler{}
 	body := []byte(`{"model":"gpt-5.5","stream":true,"store":true,"input":[{"type":"message","role":"user","content":"hello"}]}`)
 	c := newCompactBodySignalTestContext(t, "/v1/responses/compact", body)
+	c.Request.Header.Set("x-codex-beta-features", "remote_compaction_v2")
 
 	normalized, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), body)
 	require.True(t, ok)
@@ -118,36 +192,6 @@ func TestNormalizeOpenAIResponsesCompactRequest_SubpathNotPromoted(t *testing.T)
 	require.Equal(t, body, normalized)
 }
 
-// 回归 #3875：body-signal 原始请求 stream:true 时必须标记 client-stream，
-// 供响应写回阶段把上游 unary JSON 合成回 Codex remote compact v2 所需的 SSE。
-func TestNormalizeOpenAIResponsesCompactRequest_BodySignalStreamTrueMarksClientStream(t *testing.T) {
-	h := &OpenAIGatewayHandler{}
-	body := []byte(`{"model":"gpt-5.5","stream":true,"input":[{"type":"compaction_trigger"}]}`)
-	c := newCompactBodySignalTestContext(t, "/v1/responses", body)
-
-	_, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), body)
-	require.True(t, ok)
-
-	marked, exists := c.Get(service.OpenAICompactClientStreamKeyForTest())
-	require.True(t, exists)
-	require.Equal(t, true, marked)
-}
-
-func TestNormalizeOpenAIResponsesCompactRequest_BodySignalStreamFalseNotMarked(t *testing.T) {
-	h := &OpenAIGatewayHandler{}
-	for name, body := range map[string][]byte{
-		"stream_false":  []byte(`{"model":"gpt-5.5","stream":false,"input":[{"type":"compaction_trigger"}]}`),
-		"stream_absent": []byte(`{"model":"gpt-5.5","input":[{"type":"compaction_trigger"}]}`),
-	} {
-		c := newCompactBodySignalTestContext(t, "/v1/responses", body)
-		_, ok := h.normalizeOpenAIResponsesCompactRequest(c, zap.NewNop(), body)
-		require.True(t, ok, name)
-		require.Equal(t, "/v1/responses/compact", c.Request.URL.Path, name)
-		_, exists := c.Get(service.OpenAICompactClientStreamKeyForTest())
-		require.False(t, exists, "case %s 不应标记 client-stream", name)
-	}
-}
-
 // path-based compact（Codex v1 unary 协议）即使 body 带 stream:true 也不标记，
 // 保持 JSON 写回行为不变。
 func TestNormalizeOpenAIResponsesCompactRequest_PathBasedStreamTrueNotMarked(t *testing.T) {

backend/internal/handler/openai_gateway_handler.go

@@ -580,21 +580,33 @@ func isBareOpenAIResponsesPath(c *gin.Context) bool {
 	return strings.HasSuffix(normalizedPath, "/responses")
 }
 
-// normalizeOpenAIResponsesCompactRequest 统一处理两种入站 compact 形态：
-// path-based（POST /v1/responses/compact）与 Codex remote compact v2 的
-// body-signal（普通 POST /v1/responses 的 input 中携带 type=compaction_trigger，
-// 见 #3777）。body-signal 命中时在 stream 解析、compact body 归一化与
-// requireCompact 调度判定之前改写 URL path，使后续全部链路（含 passthrough
-// 分支与上游 URL 构建）与 path-based 完全一致。
+func isOpenAIRemoteCompactionV2Request(c *gin.Context, body []byte) bool {
+	stream, valid := parseOpenAICompatibleStream(body)
+	if !valid || !stream || c == nil || c.Request == nil {
+		return false
+	}
+	for _, header := range c.Request.Header.Values("x-codex-beta-features") {
+		for _, feature := range strings.Split(header, ",") {
+			if strings.TrimSpace(feature) == "remote_compaction_v2" {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// normalizeOpenAIResponsesCompactRequest keeps Codex remote compaction v2 on
+// its native streaming /responses wire and preserves the legacy body-signal
+// promotion for clients that do not explicitly advertise that protocol.
 // 返回归一化后的 body；ok=false 表示错误响应已写出，调用方应直接 return。
 func (h *OpenAIGatewayHandler) normalizeOpenAIResponsesCompactRequest(c *gin.Context, reqLog *zap.Logger, body []byte) ([]byte, bool) {
 	isCompactRequest := service.IsOpenAIResponsesCompactPathForTest(c)
 	if !isCompactRequest && isBareOpenAIResponsesPath(c) && service.HasCompactionTriggerInInput(body) {
+		if isOpenAIRemoteCompactionV2Request(c, body) {
+			return body, true
+		}
 		c.Request.URL.Path = strings.TrimRight(c.Request.URL.Path, "/") + "/compact"
 		isCompactRequest = true
-		// Codex remote compact v2 的原始请求是流式 /responses：白名单归一化会删除
-		// stream 并让上游走 unary JSON，但客户端仍按 SSE 消费响应。记录原始
-		// stream 意图，响应写回阶段据此把 JSON 合成回 SSE（#3875）。
 		clientStream := gjson.GetBytes(body, "stream").Bool()
 		if clientStream {
 			service.MarkOpenAICompactClientStream(c)