Add API key authentication for proxy endpoints.

Support multiple API keys from config, env, and CLI, enforce auth on non-public endpoints, and pass keys through remote deploy verification.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/httpapi/server.go

@@ -126,7 +126,7 @@ func NewServer(addr string, svc *service.Service) *Server {
 
 	s.http = &http.Server{
 		Addr:              addr,
-		Handler:           s.withRecorder(withCORS(mux)),
+		Handler:           s.withRecorder(withCORS(s.withAuth(mux))),
 		ReadHeaderTimeout: 10 * time.Second,
 	}
 	return s
@@ -1686,6 +1686,65 @@ func writeOpenAIError(w http.ResponseWriter, status int, kind string, message st
 	})
 }
 
+func isPublicPath(path string) bool {
+	switch path {
+	case "/", "/health", "/runtime/status", "/v1/runtime/status":
+		return true
+	default:
+		return false
+	}
+}
+
+func isAnthropicPath(path string) bool {
+	switch path {
+	case "/v1/messages", "/v1/messages/count_tokens":
+		return true
+	default:
+		return false
+	}
+}
+
+func extractAPIKey(r *http.Request) string {
+	if value := strings.TrimSpace(r.Header.Get("x-api-key")); value != "" {
+		return value
+	}
+	auth := strings.TrimSpace(r.Header.Get("Authorization"))
+	if auth == "" {
+		return ""
+	}
+	parts := strings.SplitN(auth, " ", 2)
+	if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") {
+		return ""
+	}
+	return strings.TrimSpace(parts[1])
+}
+
+func (s *Server) withAuth(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if isPublicPath(r.URL.Path) {
+			next.ServeHTTP(w, r)
+			return
+		}
+		keys := s.svc.APIKeys()
+		if len(keys) == 0 {
+			next.ServeHTTP(w, r)
+			return
+		}
+		provided := extractAPIKey(r)
+		for _, key := range keys {
+			if provided == key {
+				next.ServeHTTP(w, r)
+				return
+			}
+		}
+		if isAnthropicPath(r.URL.Path) {
+			writeAnthropicError(w, http.StatusUnauthorized, "authentication_error", "invalid or missing API key")
+			return
+		}
+		writeOpenAIError(w, http.StatusUnauthorized, "authentication_error", "invalid or missing API key")
+	})
+}
+
 func streamingHeaders(w http.ResponseWriter) {
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-cache")