feat: improve OpenAI messages compatibility for Claude Code

backend/internal/service/openai_messages_bridge.go

@@ -0,0 +1,57 @@
+package service
+
+import (
+	"bytes"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/tidwall/gjson"
+)
+
+const openAICompatMessagesBridgeContextKey = "openai_compat_messages_bridge"
+
+func isOpenAICompatMessagesBridgeBody(body []byte) bool {
+	if len(body) == 0 {
+		return false
+	}
+	if bytes.Contains(body, []byte(openAICompatClaudeCodeTodoGuardMarker)) {
+		return true
+	}
+	return isOpenAICompatMessagesBridgePromptCacheKey(gjson.GetBytes(body, "prompt_cache_key").String())
+}
+
+func isOpenAICompatMessagesBridgeRequestBody(reqBody map[string]any) bool {
+	if reqBody == nil {
+		return false
+	}
+	if input, ok := reqBody["input"].([]any); ok && inputContainsText(input, openAICompatClaudeCodeTodoGuardMarker) {
+		return true
+	}
+	return isOpenAICompatMessagesBridgePromptCacheKey(firstNonEmptyString(reqBody["prompt_cache_key"]))
+}
+
+func isOpenAICompatMessagesBridgePromptCacheKey(key string) bool {
+	key = strings.TrimSpace(key)
+	return strings.HasPrefix(key, "anthropic-metadata-") ||
+		strings.HasPrefix(key, "anthropic-cache-") ||
+		strings.HasPrefix(key, "anthropic-digest-")
+}
+
+func setOpenAICompatMessagesBridgeContext(c *gin.Context, enabled bool) {
+	if c == nil || !enabled {
+		return
+	}
+	c.Set(openAICompatMessagesBridgeContextKey, true)
+}
+
+func isOpenAICompatMessagesBridgeContext(c *gin.Context) bool {
+	if c == nil {
+		return false
+	}
+	value, ok := c.Get(openAICompatMessagesBridgeContextKey)
+	if !ok {
+		return false
+	}
+	enabled, ok := value.(bool)
+	return ok && enabled
+}