CrossRelay stage 2: Codex /v1/responses relay, config.toml manager, Codex page

internal/gateway/server.go

@@ -1,5 +1,6 @@
 // Package gateway serves the Anthropic Messages API to Claude Code and
-// the local management API to the CrossRelay UI.
+// the Responses API to Codex, plus the local management API to the
+// CrossRelay UI.
 package gateway
 
 import (
@@ -13,7 +14,9 @@ import (
 
 	"gitea.rutua.cn/kate522/CrossRelay/internal/anthropic"
 	"gitea.rutua.cn/kate522/CrossRelay/internal/claudecfg"
+	"gitea.rutua.cn/kate522/CrossRelay/internal/codexcfg"
 	"gitea.rutua.cn/kate522/CrossRelay/internal/config"
+	"gitea.rutua.cn/kate522/CrossRelay/internal/responses"
 )
 
 // Version is reported by /api/status.
@@ -70,6 +73,7 @@ func (s *Server) Handler() http.Handler {
 	mux := http.NewServeMux()
 	mux.HandleFunc("POST /v1/messages", s.withAuth(s.handleMessages))
 	mux.HandleFunc("POST /v1/messages/count_tokens", s.withAuth(s.handleCountTokens))
+	mux.HandleFunc("POST /v1/responses", s.withAuth(s.handleResponses))
 	mux.HandleFunc("GET /api/status", s.handleStatus)
 	mux.HandleFunc("GET /api/providers", s.handleListProviders)
 	mux.HandleFunc("POST /api/providers", s.handleCreateProvider)
@@ -199,6 +203,14 @@ func (s *Server) claudeManager() (*claudecfg.Manager, error) {
 	return claudecfg.New(path, filepath.Join(config.Dir(), "backups")), nil
 }
 
+func (s *Server) codexManager() (*codexcfg.Manager, error) {
+	path, err := codexcfg.DefaultPath()
+	if err != nil {
+		return nil, err
+	}
+	return codexcfg.New(path, filepath.Join(config.Dir(), "backups")), nil
+}
+
 func (s *Server) snapshotStats() Stats {
 	s.statsMu.Lock()
 	defer s.statsMu.Unlock()
@@ -222,6 +234,12 @@ func writeAPIError(w http.ResponseWriter, status int, message string) {
 	writeJSON(w, status, map[string]any{"error": message})
 }
 
+func writeResponsesError(w http.ResponseWriter, status int, errType, message string) {
+	writeJSON(w, status, responses.ErrorResponse{
+		Error: responses.Detail{Type: errType, Message: message},
+	})
+}
+
 func decodeJSON(r *http.Request, v any, limit int64) error {
 	dec := json.NewDecoder(io.LimitReader(r.Body, limit))
 	return dec.Decode(v)