What

• watch Slack socket lifecycle disconnect events in monitor startup
• fail fast by surfacing a provider error when socket mode disconnects
• add regression test to verify monitor exits on disconnect

Why

Socket mode could silently stop delivering events while the process stayed alive. Exiting fast lets the supervisor restart the provider.

Validation

• pnpm vitest run src/slack/monitor.tool-result.test.ts src/slack/monitor/provider.group-policy.test.ts
• pnpm check

Greptile Summary

This PR adds fail-fast behavior for Slack socket mode by monitoring the underlying SocketModeClient lifecycle events (disconnected, unable_to_socket_mode_start). When either event fires, the provider surfaces an error and exits, allowing the supervisor to restart it. Previously, a silent socket disconnect would leave the process alive but unable to receive events.

• Adds resolveSlackSocketLifecycleClient() to access the receiver.client from the Bolt app, with defensive null/type checks
• Introduces detachSocketLifecycleListener() with fallback support for both off and removeListener APIs
• Wires up a Promise.race between the existing abort-wait and a new disconnect-wait, so either graceful shutdown or unexpected disconnect ends the provider
• Includes proper cleanup (idempotent listener detachment) in both the error path and the finally block
• Adds a regression test that verifies the monitor rejects when a disconnected event is emitted
• Extends test helpers with socket client mock (on/off/emit) and handler tracking via a Map<string, Set<handler>>

Confidence Score: 5/5

• This PR is safe to merge — it adds defensive socket lifecycle monitoring with proper cleanup, guards against race conditions with the abort signal, and includes a focused regression test.
• The changes are well-scoped and focused on a single concern (socket disconnect detection). The implementation handles edge cases correctly: idempotent cleanup, abort-signal guard to prevent spurious rejections during graceful shutdown, defensive null checks when resolving the lifecycle client, and fallback listener removal APIs. The test properly validates the core disconnect scenario. No existing behavior is altered for HTTP mode (guarded by slackMode === "socket"). The code follows the repo's conventions (strict typing with unknown, no any, under LOC guideline).
• No files require special attention

_{Last reviewed commit: 956b807}

Context used:

• Context from dashboard - CLAUDE.md (source)
• Context from dashboard - AGENTS.md (source)