hermes - 💡(How to fix) Fix bug(dingtalk): session_webhook expires silently within same Stream Mode connection, causing message delivery failures [1 participants]

Bug Description

When the DingTalk Stream Mode WebSocket connection stays alive for an extended period without any incoming messages, the session_webhook URL can expire before the WebSocket disconnects. The adapter relies on the webhook for replying, but with no new incoming message to refresh it, the bot can receive messages via WebSocket but cannot reply — a silent failure that looks like "DingTalk unresponsive" to end users.

Steps to Reproduce

1. Start Hermes gateway with DingTalk Stream Mode connected
2. Let the connection idle for longer than the webhook TTL (varies, observed after hours)
3. No incoming DingTalk messages during this period
4. A cron job or proactive message attempts to send to a DingTalk chat
5. Gateway logs: [Dingtalk] No valid session_webhook for chat_id=xxx
6. Message delivery silently fails

Root Cause

The session_webhook URL has a TTL set by DingTalk platform. The webhook is only refreshed when a new incoming message arrives (via the callback). The adapter stores it with expired_time_ms, and correctly detects expiration — but the only way to get a fresh webhook is an incoming message. If no one sends a message, the webhook stays expired until a reconnect or a new incoming message.

What We Already Fixed

In _run_stream_client(), we clear session_webhooks on reconnect, so stale webhooks from old connections don't persist. This works when the WebSocket actually disconnects.

What Is Still Broken

When the WebSocket stays connected but the webhook TTL expires, clear() is never called because no reconnect happens. Any send attempt fails silently.

Expected Behavior

1. (Minimum) The adapter should log a clear warning before the webhook expires
2. (Better) Proactive webhook refresh via keepalive messages
3. (Best) Fallback to DingTalk Robot OpenAPI for sending when session_webhook is unavailable

Environment

• Hermes Agent running on Ubuntu (non-Docker)
• DingTalk Stream Mode adapter
• Observed on 2026-05-11

Related

• #17370 feat(dingtalk): proactive messaging via Robot OpenAPI
• #14336 feat(dingtalk): proactive messaging via Robot OpenAPI