Summary

Addresses review findings on the v0.9.21 release PR (#8989) for the Slack member-accounts work (#8979, #8986).

• removeSlackSearchInstallation now runs in a transaction that takes lockOrganizationSlackApp, so an admin removing a Search bot serializes with in-flight member Slack setup like every other Slack Search installation write
• A custom slack_app row holding the shared app's ID is refused at member setup start (before OAuth, so the admin sees "This Slack app belongs to another installation owner."), and completion's existing FOR UPDATE read throws a conflict for one created mid-authorization. Previously member setup also refused, but late and as an unclassified error / generic popup failure; bot setup already had its own pre-check. ensureSharedSlackAppRow stays ON CONFLICT DO NOTHING
• Lock TSDoc states the contract precisely: Slack revocations (must never wait on setup, and would invert lock order) and the bot-credential delete cascade skip it — they only withdraw a bot, which member setup tolerates
• Changelog empty state: drop the last earlier release, whose notes sat below the 148px viewBox and whose heading only grazed the bottom edge inside the fade's fully transparent end; render is unchanged and the graphic keeps its siblings' 148px height

Type of Change

• Bug fix

Testing

• slack-shared-member-accounts.integration.ts (real Postgres/Redis): removal waits on the Slack organization lock; member setup refuses a custom row holding the shared app ID at start and (asserting code: 'conflict') at completion, writing nothing; both lock-contention cases share one whileOrganizationSlackAppLocked helper whose barrier is scoped to backends waiting on that lock
• Targeted suites: slack-search, credential-groups, slack-search lib, knowledge Slack and credential-group routes, resource empty states, credentials (813 tests)
• biome on changed files; check:api-validation:strict, check:comment-hygiene, check:test-patterns, check:boundaries, check:utils
• Full type-check, check:audits, and integration run in CI

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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