fix(webhooks): check existing path owners before claiming on deploy

[waleedlatif1]

Summary

• Deploy-time webhook registration now checks for another workflow's live webhook on the same path before claiming it, matching the existing check on the other webhook write paths
• Conflicts surface as the existing 409 "path already in use" error

Type of Change

• Bug fix

Testing

• New registration-store.integration.ts against real Postgres (fails without the fix)
• lib/webhooks unit tests, lint, type-check, check:audits, full bun run test

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)

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Oct 3, 2026 7:29pm UTC

[greptile-apps]

Confidence Score: 5/5

[Critical risk] Webhook path ownership validation during deployment.

The PR appears safe to merge; no actionable regression was identified.

Summary

Deploy-time webhook registration now checks existing path owners before claiming a path, including owners represented only by live legacy webhook rows.

• Adds PostgreSQL integration coverage for conflicting and free paths.
• Updates the unit-test mock for the new ownership lookup.

_{Reviews (1) · Last reviewed commit: "fix(webhooks): check existing path owner..."}

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Re-trigger cubic}