hermes - 💡(How to fix) Fix graceful_shutdown: Discord 403 during shutdown notification can delay clean exit [3 pull requests]

Bug Description

During gateway shutdown, the gateway attempts to send a shutdown notification message to Discord. If the Discord bot has lost access to a channel (403 Forbidden), the error can delay the shutdown sequence, causing systemd to kill the process with SIGKILL after TimeoutStopSec.

Steps to Reproduce

1. Run the Hermes gateway with Discord enabled
2. Have the Discord bot removed from a server (or have its permissions revoked)
3. Send SIGTERM to the gateway process (e.g., via auto-update cron or systemctl restart)
4. Gateway tries to send shutdown notification to Discord
5. Discord returns 403 Forbidden (Missing Access)
6. Shutdown is delayed; systemd may timeout and force-kill

Actual Behavior

ERROR gateway.platforms.discord: [Discord] Failed to send Discord message: 403 Forbidden (error code: 50001): Missing Access

Traceback from gateway/platforms/discord.py during the send() call in the shutdown sequence.

Expected Behavior

Shutdown notifications to a platform that returns 403 should be handled gracefully - log a warning and continue. A failed goodbye message should not materially delay process exit.

Environment

• Linux (Ubuntu 24.04)
• Gateway systemd service with Restart=always
• Discord bot token configured

Logs from Incident

May 07 01:01:38 systemd: Stopping hermes-gateway.service...
May 07 01:01:39 ERROR gateway.platforms.discord: [Discord] Failed to send Discord message: 403 Forbidden (error code: 50001): Missing Access
May 07 01:03:08 systemd: State stop-sigterm timed out. Killing.