Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/openai_compact_stream_bridge.go

@@ -0,0 +1,216 @@
+package service
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+// openAICompactClientStreamKey 标记 body-signal compact 请求（Codex remote
+// compact v2，见 #3777）的原始 body 携带 stream:true。白名单归一化会删除
+// stream 字段并让上游走 unary /responses/compact（JSON），但客户端仍按
+// Responses SSE 协议消费响应：它必须收到 response.output_item.done（其中恰好
+// 一个 type=compaction 的 item）和 response.completed，否则报
+// "stream closed before response.completed" 并无限重连（#3875）。
+const openAICompactClientStreamKey = "openai_compact_client_stream"
+
+// MarkOpenAICompactClientStream 由 handler 在 body-signal 提升时调用，记录
+// 客户端的原始 stream 意图，供响应写回阶段决定是否合成 SSE。
+func MarkOpenAICompactClientStream(c *gin.Context) {
+	if c == nil {
+		return
+	}
+	c.Set(openAICompactClientStreamKey, true)
+}
+
+func OpenAICompactClientStreamKeyForTest() string {
+	return openAICompactClientStreamKey
+}
+
+func openAICompactClientWantsStream(c *gin.Context) bool {
+	if c == nil {
+		return false
+	}
+	value, ok := c.Get(openAICompactClientStreamKey)
+	if !ok {
+		return false
+	}
+	wants, _ := value.(bool)
+	return wants
+}
+
+// writeOpenAICompactSSEBridge 将 unary compact 的最终 JSON 响应按 Codex remote
+// compact v2 的消费协议合成为最小 Responses SSE 流写回客户端。仅当请求被标记
+// 为 body-signal 客户端流式、状态码为 2xx 且 body 是合法 JSON 对象时生效；
+// 返回 false 表示未写出任何内容，调用方应按原路径写回。
+//
+// 若下游心跳已把响应头提交为 200（见 openAICompactSSEKeepalive），则本函数
+// 必须接管一切写回：非 2xx 或不可合成的响应降级为 response.failed 终止事件，
+// 不能再返回 false（否则调用方的 JSON 写回会与已提交的 SSE 流交错）。
+func writeOpenAICompactSSEBridge(c *gin.Context, statusCode int, finalResponse []byte) bool {
+	if c == nil || !openAICompactClientWantsStream(c) {
+		return false
+	}
+	// 先停心跳再写回，避免注释行与最终事件交错；停止后经互斥锁与心跳
+	// goroutine 建立 happens-before，可安全接管 ResponseWriter。
+	committed := StopOpenAICompactSSEKeepaliveCommitted(c)
+	if statusCode < 200 || statusCode >= 300 {
+		if committed {
+			writeOpenAICompactSSEFailure(c, statusCode, finalResponse)
+			return true
+		}
+		return false
+	}
+	payload, ok := buildOpenAICompactSSEPayload(finalResponse)
+	if !ok {
+		if committed {
+			writeOpenAICompactSSEFailure(c, http.StatusBadGateway, finalResponse)
+			return true
+		}
+		return false
+	}
+	if !committed {
+		header := c.Writer.Header()
+		header.Set("Content-Type", "text/event-stream")
+		header.Set("Cache-Control", "no-cache")
+		header.Set("Connection", "keep-alive")
+		header.Set("X-Accel-Buffering", "no")
+		c.Writer.WriteHeader(statusCode)
+	}
+	_, _ = c.Writer.Write(payload)
+	c.Writer.Flush()
+	return true
+}
+
+// writeOpenAICompactSSEFailure 从上游错误 body 提取错误消息后，以
+// response.failed 终止事件回传。仅用于心跳已提交 200、无法再按 HTTP 状态码
+// 回传错误的场景。
+func writeOpenAICompactSSEFailure(c *gin.Context, statusCode int, errorBody []byte) {
+	message := ""
+	if len(errorBody) > 0 {
+		message = sanitizeUpstreamErrorMessage(strings.TrimSpace(extractUpstreamErrorMessage(errorBody)))
+	}
+	if message == "" {
+		message = "Upstream compact request failed with HTTP " + strconv.Itoa(statusCode)
+	}
+	writeOpenAICompactSSEFailureMessage(c, statusCode, "upstream_error", message)
+}
+
+// writeOpenAICompactSSEFailureMessage 写出 response.failed 终止事件。Codex 对
+// 流式 Responses 请求把 response.failed 作为合法终止事件处理（普通 error 帧
+// 不被识别，会退化为 "stream closed before response.completed" 盲重连）。
+// 同时标记流内错误，保证挂在 200 流上的失败仍进入 ops 错误看板。
+func writeOpenAICompactSSEFailureMessage(c *gin.Context, statusCode int, errType, message string) {
+	if c == nil {
+		return
+	}
+	MarkOpsStreamError(c, errType, message, statusCode)
+	payload, err := json.Marshal(map[string]any{
+		"type": "response.failed",
+		"response": map[string]any{
+			"id":     "resp_" + strings.ReplaceAll(uuid.NewString(), "-", ""),
+			"object": "response",
+			"status": "failed",
+			"output": []any{},
+			"error": map[string]any{
+				"code":    errType,
+				"message": message,
+			},
+		},
+	})
+	if err != nil {
+		return
+	}
+	_, _ = c.Writer.Write([]byte("event: response.failed\ndata: "))
+	_, _ = c.Writer.Write(payload)
+	_, _ = c.Writer.Write([]byte("\n\n"))
+	c.Writer.Flush()
+}
+
+// buildOpenAICompactSSEPayload 把 compact 的 Response JSON 转成 SSE 事件序列：
+// 每个 output[] item 一条 response.output_item.done，最后一条 response.completed
+// 携带完整 response 对象。Codex 的 SSE 解析只从 output_item.done 收集 item，
+// 并要求 response.completed 的 response.id 必填、usage（若存在）必须携带
+// input_tokens/output_tokens/total_tokens 整数字段，否则整条 completed 事件
+// 解析失败，故此处做兜底修补。
+func buildOpenAICompactSSEPayload(finalResponse []byte) ([]byte, bool) {
+	if len(finalResponse) == 0 || !gjson.ValidBytes(finalResponse) {
+		return nil, false
+	}
+	if !gjson.ParseBytes(finalResponse).IsObject() {
+		return nil, false
+	}
+	// SSE 的 data 行不允许出现裸换行：上游 JSON 可能是 pretty-printed 形态，
+	// 嵌入前必须压缩为单行。
+	var compacted bytes.Buffer
+	if err := json.Compact(&compacted, finalResponse); err != nil {
+		return nil, false
+	}
+	response := compacted.Bytes()
+	root := gjson.ParseBytes(response)
+	if strings.TrimSpace(root.Get("id").String()) == "" {
+		next, err := sjson.SetBytes(response, "id", "resp_"+strings.ReplaceAll(uuid.NewString(), "-", ""))
+		if err != nil {
+			return nil, false
+		}
+		response = next
+	}
+	if usage := gjson.GetBytes(response, "usage"); usage.Exists() && !openAICompactUsageParsableByCodex(usage) {
+		next, err := sjson.DeleteBytes(response, "usage")
+		if err != nil {
+			return nil, false
+		}
+		response = next
+	}
+
+	var buf bytes.Buffer
+	outputIndex := 0
+	appendEvent := func(eventType string, data []byte) {
+		_, _ = buf.WriteString("event: ")
+		_, _ = buf.WriteString(eventType)
+		_, _ = buf.WriteString("\ndata: ")
+		_, _ = buf.Write(data)
+		_, _ = buf.WriteString("\n\n")
+	}
+	for _, item := range gjson.GetBytes(response, "output").Array() {
+		if !item.IsObject() {
+			continue
+		}
+		event, err := sjson.SetBytes([]byte(`{"type":"response.output_item.done"}`), "output_index", outputIndex)
+		if err != nil {
+			return nil, false
+		}
+		event, err = sjson.SetRawBytes(event, "item", []byte(item.Raw))
+		if err != nil {
+			return nil, false
+		}
+		appendEvent("response.output_item.done", event)
+		outputIndex++
+	}
+
+	completed, err := sjson.SetRawBytes([]byte(`{"type":"response.completed"}`), "response", response)
+	if err != nil {
+		return nil, false
+	}
+	appendEvent("response.completed", completed)
+	return buf.Bytes(), true
+}
+
+func openAICompactUsageParsableByCodex(usage gjson.Result) bool {
+	if !usage.IsObject() {
+		return false
+	}
+	for _, field := range []string{"input_tokens", "output_tokens", "total_tokens"} {
+		if usage.Get(field).Type != gjson.Number {
+			return false
+		}
+	}
+	return true
+}