feat: improve OpenAI messages compatibility for Claude Code

backend/internal/service/openai_messages_replay_guard.go

@@ -0,0 +1,90 @@
+package service
+
+import (
+	"encoding/json"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/apicompat"
+)
+
+const openAICompatAnthropicReplayMaxTailMessages = 12
+
+func applyAnthropicCompatFullReplayGuard(req *apicompat.AnthropicRequest) bool {
+	if req == nil || len(req.Messages) <= openAICompatAnthropicReplayMaxTailMessages {
+		return false
+	}
+
+	start := len(req.Messages) - openAICompatAnthropicReplayMaxTailMessages
+	start = expandAnthropicCompatTrimBoundary(req.Messages, start)
+	if start <= 0 {
+		return false
+	}
+
+	req.Messages = append([]apicompat.AnthropicMessage(nil), req.Messages[start:]...)
+	return true
+}
+
+func expandAnthropicCompatTrimBoundary(messages []apicompat.AnthropicMessage, start int) int {
+	if start <= 0 || start >= len(messages) {
+		return start
+	}
+
+	toolUseIndex := make(map[string]int)
+	toolResultIndex := make(map[string]int)
+	for i, msg := range messages {
+		uses, results := anthropicCompatMessageToolIDs(msg)
+		for _, id := range uses {
+			if _, exists := toolUseIndex[id]; !exists {
+				toolUseIndex[id] = i
+			}
+		}
+		for _, id := range results {
+			if _, exists := toolResultIndex[id]; !exists {
+				toolResultIndex[id] = i
+			}
+		}
+	}
+
+	for {
+		next := start
+		for i := start; i < len(messages); i++ {
+			uses, results := anthropicCompatMessageToolIDs(messages[i])
+			for _, id := range results {
+				if useIdx, ok := toolUseIndex[id]; ok && useIdx < next {
+					next = useIdx
+				}
+			}
+			for _, id := range uses {
+				if resultIdx, ok := toolResultIndex[id]; ok && resultIdx < next {
+					next = resultIdx
+				}
+			}
+		}
+		if next == start {
+			return start
+		}
+		start = next
+	}
+}
+
+func anthropicCompatMessageToolIDs(msg apicompat.AnthropicMessage) ([]string, []string) {
+	var blocks []apicompat.AnthropicContentBlock
+	if err := json.Unmarshal(msg.Content, &blocks); err != nil {
+		return nil, nil
+	}
+
+	uses := make([]string, 0, 1)
+	results := make([]string, 0, 1)
+	for _, block := range blocks {
+		switch block.Type {
+		case "tool_use":
+			if block.ID != "" {
+				uses = append(uses, block.ID)
+			}
+		case "tool_result":
+			if block.ToolUseID != "" {
+				results = append(results, block.ToolUseID)
+			}
+		}
+	}
+	return uses, results
+}