fix(slack): prevent duplicate workspace installs

[RSO]

Summary

• Prevent Slack workspaces from being connected to multiple Kilo owners by checking Slack team ID conflicts before persisting installs.
• Add a Slack-specific unique index on platform installation ID, with migration cleanup for historical duplicate workspace rows.
• Surface a helpful duplicate-workspace message on the Slack integration page after OAuth callback redirects.

Verification

• Browser smoke tested the Slack integration error state and confirmed the duplicate-workspace alert is shown.

Visual Changes

N/A

Reviewer Notes

• Migration preserves the active or most-recent Slack integration per workspace and suspends older duplicate rows before adding the unique index.
• Focused automated checks run locally: pnpm test:db, pnpm test -- apps/web/src/lib/integrations/slack-service.test.ts, pnpm format, scripts/typecheck-all.sh --changes-only, and pnpm --filter web typecheck.

[kilo-code-bot]

Code Review Summary

Status: 2 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	2
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/db/src/migrations/0108_wise_psylocke.sql	18	Duplicate cleanup keeps an arbitrary Slack integration because LIMIT 1 has no deterministic ordering.
packages/db/src/migrations/0108_wise_psylocke.sql	56	Unique index is created without CONCURRENTLY, which can lock writes on a populated table.

Fix these issues in Kilo Cloud

Other Observations (not in diff)

Issues found in unchanged code that cannot receive inline comments:

File	Line	Issue

Files Reviewed (9 files)

• apps/web/src/app/api/integrations/slack/callback/route.ts - 0 issues
• apps/web/src/components/integrations/SlackIntegrationDetails.tsx - 0 issues
• apps/web/src/lib/integrations/slack-service.test.ts - 0 issues
• apps/web/src/lib/integrations/slack-service.ts - 0 issues
• apps/web/src/routers/slack-router.ts - 0 issues
• packages/db/src/migrations/0108_wise_psylocke.sql - 2 issues
• packages/db/src/migrations/meta/0108_snapshot.json - 0 issues
• packages/db/src/migrations/meta/_journal.json - 0 issues
• packages/db/src/schema.ts - 0 issues

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_{Reviewed by gpt-5.5-2026-04-23 · 384,483 tokens}