feat: improve goal mode and Codex App resilience

.trellis/tasks/08-18-codexapp-retry-resume/task.json

@@ -0,0 +1,31 @@
+{
+  "id": "codexapp-retry-resume",
+  "name": "codexapp-retry-resume",
+  "title": "修复 Codex App 重试中断",
+  "description": "",
+  "status": "completed",
+  "dev_type": null,
+  "scope": null,
+  "package": null,
+  "priority": "P2",
+  "creator": "shiyue",
+  "assignee": "shiyue",
+  "createdAt": "2026-08-18",
+  "completedAt": "2026-08-18",
+  "branch": null,
+  "base_branch": "main",
+  "worktree_path": null,
+  "commit": null,
+  "pr_url": null,
+  "subtasks": [],
+  "children": [],
+  "parent": null,
+  "relatedFiles": [
+    "lib/codex-app-runtime.js",
+    "scripts/mock-codex-app-server.js",
+    "scripts/regression.js",
+    ".trellis/spec/backend/error-handling.md"
+  ],
+  "notes": "区分 Codex App 重连过程通知与终端错误；定向及完整回归通过。",
+  "meta": {}
+}