[Fix] Slack Pick fails with out-of-date when structured prompts refresh

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

N/A — internal Roomote work requested by a maintainer after investigating live Slack “prompt is out of date” failures.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Slack structured prompts no longer mint dead Pick buttons during OpenCode’s placeholder→real question stream:

• Streaming placeholders (Provide the requested input. / id response / no options) are not posted to Slack or Linear, and no pending integration state is written for them.
• When a same-requestId enrich re-post cannot update the original card in place, the old message is neutralized (or deleted if that update fails).
• If a user still clicks a button with a stale questionId but the same index and a still-valid answer for the current question, Slack accepts it under the current question id instead of rejecting as out of date.

How it was tested

• pnpm --filter @roomote/worker exec vitest run for slack-mention, linear-agent, and request-user-input callback tests
• pnpm --filter @roomote/slack exec vitest run src/__tests__/handle-followup-answer.test.ts
• Pre-push suite (oxlint, residual lint, check-types:fast, knip)

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

1 issue outstanding. See task

• Restrict stale Pick recovery to option labels still present in the refreshed question (packages/slack/src/handle-followup-answer.ts:315-331). OpenCode questions normally have isOther: true, so freeformOk currently treats every non-empty label from an obsolete card as valid even when the refreshed prompt removed that option or changed meaning. A stale Pick can therefore be submitted under an unrelated new question ID; button values are option picks, not custom answers, so a mismatched label should remain out of date.

_{Reviewed c508906}