feat: improve OpenAI messages compatibility for Claude Code

backend/internal/service/openai_messages_todo_guard.go

@@ -0,0 +1,121 @@
+package service
+
+import (
+	"encoding/json"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/apicompat"
+)
+
+const (
+	openAICompatClaudeCodeTodoGuardMarker = "<sub2api-claude-code-todo-guard>"
+	openAICompatClaudeCodeTodoGuardText   = openAICompatClaudeCodeTodoGuardMarker + "\nWhen using Claude Code todo or task tracking tools, keep the visible task list consistent. Do not send final or summary text while any item remains in_progress. Before finishing, asking the user to choose, or reporting a blocker, update the todo list so completed work is completed and deferred work is pending/open; leave an item in_progress only when active work will continue in the same turn.\n</sub2api-claude-code-todo-guard>"
+)
+
+func appendOpenAICompatClaudeCodeTodoGuard(req *apicompat.ResponsesRequest) bool {
+	if req == nil || len(req.Input) == 0 {
+		return false
+	}
+
+	var items []apicompat.ResponsesInputItem
+	if err := json.Unmarshal(req.Input, &items); err != nil {
+		return false
+	}
+	if len(items) == 0 || responsesInputItemsContainText(items, openAICompatClaudeCodeTodoGuardMarker) {
+		return false
+	}
+
+	content, err := json.Marshal([]apicompat.ResponsesContentPart{{
+		Type: "input_text",
+		Text: openAICompatClaudeCodeTodoGuardText,
+	}})
+	if err != nil {
+		return false
+	}
+
+	guard := apicompat.ResponsesInputItem{
+		Type:    "message",
+		Role:    "developer",
+		Content: content,
+	}
+
+	insertAt := 0
+	for insertAt < len(items) && items[insertAt].Type == "message" && items[insertAt].Role == "developer" {
+		insertAt++
+	}
+
+	items = append(items, apicompat.ResponsesInputItem{})
+	copy(items[insertAt+1:], items[insertAt:])
+	items[insertAt] = guard
+
+	input, err := json.Marshal(items)
+	if err != nil {
+		return false
+	}
+	req.Input = input
+	return true
+}
+
+func appendOpenAICompatClaudeCodeTodoGuardToRequestBody(reqBody map[string]any) bool {
+	if reqBody == nil {
+		return false
+	}
+
+	input, ok := reqBody["input"].([]any)
+	if !ok || len(input) == 0 || inputContainsText(input, openAICompatClaudeCodeTodoGuardMarker) {
+		return false
+	}
+
+	guard := map[string]any{
+		"type": "message",
+		"role": "developer",
+		"content": []any{
+			map[string]any{
+				"type": "input_text",
+				"text": openAICompatClaudeCodeTodoGuardText,
+			},
+		},
+	}
+
+	insertAt := 0
+	for insertAt < len(input) {
+		item, ok := input[insertAt].(map[string]any)
+		if !ok || strings.TrimSpace(firstNonEmptyString(item["type"])) != "message" || strings.TrimSpace(firstNonEmptyString(item["role"])) != "developer" {
+			break
+		}
+		insertAt++
+	}
+
+	input = append(input, nil)
+	copy(input[insertAt+1:], input[insertAt:])
+	input[insertAt] = guard
+	reqBody["input"] = input
+	return true
+}
+
+func responsesInputItemsContainText(items []apicompat.ResponsesInputItem, needle string) bool {
+	needle = strings.TrimSpace(needle)
+	if needle == "" {
+		return false
+	}
+	for _, item := range items {
+		if strings.Contains(string(item.Content), needle) {
+			return true
+		}
+	}
+	return false
+}
+
+func inputContainsText(input []any, needle string) bool {
+	needle = strings.TrimSpace(needle)
+	if needle == "" {
+		return false
+	}
+	for _, item := range input {
+		b, err := json.Marshal(item)
+		if err == nil && strings.Contains(string(b), needle) {
+			return true
+		}
+	}
+	return false
+}