fix(chat): recover session list from snapshots

tkmind-proxy.mjs

@@ -2187,14 +2187,6 @@ export function createTkmindProxy({
             }
           }
 
-          if (healthyTargets === 0) {
-            res.status(502).json({ message: lastFailure ?? '后端连接失败，请稍后重试' });
-            return;
-          }
-          if (healthyTargets < targets.length) {
-            res.setHeader('X-TKMind-Degraded', '1');
-          }
-
           const directSessionIds = [...owned].filter(isDirectChatSessionId);
           const ownedMissingFromGoose = [...owned].filter((sessionId) => !sessionsById.has(sessionId));
           const snapshotFallbackIds = [...new Set([...directSessionIds, ...ownedMissingFromGoose])];
@@ -2231,6 +2223,14 @@ export function createTkmindProxy({
             }
           }
 
+          if (healthyTargets === 0 && owned.size > 0 && sessionsById.size === 0) {
+            res.status(502).json({ message: lastFailure ?? '后端连接失败，请稍后重试' });
+            return;
+          }
+          if (healthyTargets < targets.length || healthyTargets === 0) {
+            res.setHeader('X-TKMind-Degraded', '1');
+          }
+
           const sessions = [...sessionsById.values()].sort(sortSessionsByRecent);
           await enrichSessionHistory(sessions, req.currentUser.id);
           if (typeof userAuth.getSessionOrigins === 'function' && sessions.length > 0) {