Fix cross-platform reply race: per-command context via AsyncLocalStorage

[htilly]

Summary

Follow-up to #340. index.js kept three module-level globals, currentPlatform, currentChannel and currentIsAdmin. Each command set them when it started, but they were read much later: after awaits, and in timers such as the 5-minute flush-vote timer. Slack commands run fire-and-forget, so overlapping Slack and Discord commands could overwrite each other's values. The result:

• a reply could go to the wrong platform, e.g. a Slack channel ID sent to Discord or the other way round
• help could make the wrong admin decision

Changes

• lib/command-context.js (new): an AsyncLocalStorage holding {platform, channel, isAdmin, userName}. It follows a command through every await, promise chain and setTimeout the command starts.
• lib/command-router.js: the public entry points (routeCommand, processInput, handleNaturalLanguage) now run inside the command's context. The optional setContext dependency is still accepted.
• index.js:
  • Removed the three globals and the setContext closure.
  • The Slack and Discord reaction handlers run in their own context.
  • _slackMessage, help, Discord DMs, bestof and add-handlers' getCurrentPlatform now read the current command's context.
  • Sends made outside any command (startup and admin notices) go to Slack if it is configured, otherwise to Discord. The old code always defaulted to Slack, even in Discord-only setups.

Timers such as the flush vote, gong cleanup and TTS cleanup needed no changes, because they inherit the context of the command that created them.

Test plan

• npm test: 867 passing
• New test/command-context.test.mjs: the context survives awaits and timers, overlapping runs are isolated, and there is no context outside a command
• New router tests: an overlapping Slack command and Discord command each see their own platform and channel, and a timer started by a handler keeps its command's context after another command has run
• node --check on the changed files
• Manual check on a mixed Slack + Discord install: run commands on both platforms at the same time, and try flushvote followed by a command on the other platform

🤖 Generated with Claude Code

https://claude.ai/code/session_01HC2Ba1dYTJaUgH63ks2N1q

---

Generated by Claude Code