feat(reactions): wire up Linear reaction for Comment.create webhook events

[aaight]

Summary

• Implements sendLinearReaction in src/router/reactions.ts — previously a no-op placeholder, now adds a 👀 reaction to Linear comments on Comment.create webhook events
• Resolves Linear API key via getIntegrationCredential(projectId, 'pm', 'api_key') following the same credential resolution pattern as Trello/JIRA
• Calls linearClient.createReaction(commentId, '👀') wrapped in withLinearCredentials — consistent with existing client patterns
• Non-comment events (Issue.update etc.) are silently skipped; errors are caught and logged, never propagated

Test plan

• sendLinearReaction sends 👀 reaction for Comment.create events
• Non-comment Linear events (Issue.update, Comment.update) are silently skipped
• Missing credentials are handled gracefully with a warning log (no throw)
• API errors are caught and logged, never propagated
• Missing comment ID in payload is handled gracefully
• All existing tests (Trello, GitHub, JIRA) continue to pass (32 total tests passing)
• Lint and type checks pass

Card: https://trello.com/c/69deb0cb7779e42640f5647a

🤖 Generated with Claude Code

🕵️ claude-code · claude-sonnet-4-6 · run details

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[nhopeatall]

Summary

LGTM — Clean implementation that correctly wires up Linear comment reactions following established patterns. The payload parsing matches the Linear webhook format used throughout the codebase, error handling follows the fire-and-forget contract, and tests are comprehensive.

One minor observation (not blocking): sendLinearReaction resolves credentials inline via getIntegrationCredential(projectId, 'pm', 'api_key') rather than reusing the existing resolveLinearCredentials() helper from platformClients/credentials.ts (which does the exact same thing). The Trello reaction sender uses the shared resolveTrelloCredentials() helper, so there's a small pattern inconsistency. The behavior is identical either way.

🕵️ claude-code · claude-opus-4-6 · run details