refactor: consolidate Devin session logic into reusable action

[keithwillcode]

What does this PR do?

This PR consolidates duplicated Devin session management logic from three workflows into a single reusable GitHub action. Originally, the Stale Community PR Devin Completion workflow was creating duplicate sessions (as seen in PR #22542), and the fix revealed significant code duplication across workflows.

Changes

1. New reusable action (.github/actions/devin-session/action.yml):

   • Checks if PR was created by a Devin session (from PR body)
   • Searches PR comments for existing Devin sessions
   • Verifies session is active (working, blocked, or resumed status) for both PR body and comment-based sessions
   • Returns session info for reuse or signals to create new session

2. Updated workflows to use the new action:

   • stale-pr-devin-completion.yml - now reuses existing sessions
   • cubic-devin-review.yml - refactored to use action
   • devin-conflict-resolver.yml - refactored to use action

Updates since last revision

• Fixed Cubic AI feedback (confidence 9/10): Added active status check for PR body sessions. Previously, sessions found from PR body weren't verified as active before reuse, unlike comment-based sessions. Now both code paths consistently check for working, blocked, or resumed status.

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. N/A - workflow/action changes only.
• I confirm automated tests are in place that prove my fix is effective or that my feature works. N/A - GitHub Actions workflows, tested by triggering.

How should this be tested?

1. Test session reuse on stale PR workflow:

   • Find a PR with an existing Devin session comment
   • Add the stale label
   • Verify the workflow sends a message to the existing session (comment should say "existing Devin session has been notified")

2. Test session reuse on conflict resolver:

   • Find a PR with conflicts and an existing Devin session
   • Add the devin-conflict-resolution label
   • Verify session reuse behavior

3. Test Cubic AI review workflow:

   • Trigger a Cubic AI review on a PR with existing Devin session
   • Verify session reuse

Human Review Checklist

• Verify checkout step is placed before the action usage in all workflows (required for local composite actions)
• Confirm the session patterns in the action cover all three use cases: stale PR, Cubic AI, conflict resolution
• Verify the action outputs (has-existing-session, session-id, session-url) are correctly consumed
• Verify active status check is applied to PR body sessions (Fixed per Cubic AI feedback)
• Note: ~83 lines removed from duplicated logic across workflows

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR that start with 'DevinAI' or '@devin'.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[cubic-dev-ai]

1 issue found across 4 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name=".github/actions/devin-session/action.yml">

<violation number="1" location=".github/actions/devin-session/action.yml:70">
P1: Missing active status check for PR body sessions. When a session is found from the PR body, the code doesn't verify if it's active (`working`, `blocked`, or `resumed`), unlike the comment-based session check below. This could cause workflows to try reusing completed or failed sessions.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[github-actions]

Devin AI is addressing Cubic AI's review feedback

New feedback has been sent to the existing Devin session.

View Devin Session

[github-actions]

E2E results are ready!

• Workflow #99084.1 latest results