Error occurred
    │
    ▼
Check HTTP status
    │
    ├── 400 ──▶ Check request format
    │
    ├── 401 ──▶ Re-authenticate
    │
    ├── 403 ──▶ Check permissions
    │
    ├── 404 ──▶ Verify policyId
    │
    ├── 410 ──▶ Link expired, request new
    │
    ├── 429 ──▶ Wait, then retry
    │
    ├── 500 ──▶ Server issue, contact support
    │
    └── Contract ──▶ Check reason string