Shepherd Prs Agent Skill

Shepherding Pull Requests Skill (flutter/flutter)

This skill defines the canonical runbook for shepherding pull requests in the flutter/flutter repository using native GitHub CLI (gh) commands.

1. Checking PR Status

When the user asks for the status of open or approved PRs:

• List Your Own Open PRs:

   gh pr list --repo flutter/flutter --author <username> --state open --json number,title,url,mergeable,reviewDecision

• List Shepherded / Reviewed Third-Party PRs:

   gh pr list --repo flutter/flutter --search "reviewed-by:<username> -author:<username> is:open" --json number,title,url,mergeable,reviewDecision

• Inspect Detailed PR Checks:

   gh pr checks <number> --repo flutter/flutter

• Inspect Reviews, Labels, and Comments:

   gh pr view <number> --repo flutter/flutter --json labels,reviewDecision,reviews,comments

2. Pre-Autosubmit Verification Rules

Before applying or re-applying the autosubmit label (gh pr edit <number> --repo flutter/flutter --add-label autosubmit), always perform the following pre-flight verification checks to ensure the autosubmit bot will not reject or strip the label:

• Check Previous autosubmit Removal History in Comments:
• Always check if the autosubmit label was previously removed by the auto-submit bot by checking PR comments:

     gh pr view <number> --repo flutter/flutter --json comments

• Look for messages from auto-submit such as "autosubmit label was removed...".
• If the label was previously removed, identify the exact reason stated by the bot (e.g., failing CI checks, insufficient approvals, merge conflicts, or stale branch) and confirm that the underlying issue has been resolved before re-applying autosubmit.

• Verify Freshness of Base Commit (>7 Days Old):
• Check whether the PR's base commit is stale (>7 days old).
• If the base commit is more than 7 days old, always instruct running or execute a branch update before attempting to add autosubmit:

     gh pr update-branch <number> --repo flutter/flutter

• Do not apply autosubmit until the branch update is complete and CI checks on the updated branch succeed.

• Strictly Verify Required Reviewer Approvals:
• Strictly verify that third-party contributor PRs (CONTRIBUTOR, FIRST_TIME_CONTRIBUTOR, NONE) have at least 2 team member approvals (MEMBER or OWNER) before adding autosubmit so the bot doesn't remove it again.
• Check reviews in gh pr view <number> --repo flutter/flutter --json reviews to confirm the number of approvals from Flutter team members.

• Verify All Status Checks Are 100% Passing:
• The Flutter autosubmit bot automatically strips the autosubmit label whenever any CI check fails.
• Verify that all status checks are passing (SUCCESS/pass).
• If any check is flaky, failing, or pending a retry:
• Do NOT apply the autosubmit label immediately.
• Inform the user of the failing check and instruct them to retry it first.
• Only apply the autosubmit label after all retried checks complete successfully:

        gh pr edit <number> --repo flutter/flutter --add-label autosubmit

3. Third-Party Contributor PRs (2-Reviewer Requirement)

• Pull requests authored by third-party contributors (CONTRIBUTOR, FIRST_TIME_CONTRIBUTOR, NONE) require two explicit approvals from Flutter team members (MEMBER or OWNER) before the autosubmit bot will merge them.
• If only one team member has approved a third-party PR and the autosubmit label is applied, the autosubmit bot will remove the label.
• *Action*: Strictly verify via gh pr view <number> --repo flutter/flutter --json reviews that at least 2 team member approvals are present before adding autosubmit so the bot doesn't remove it again. If only 1 approval exists, remind the user to request a second reviewer before applying the label.

4. Failed Checks & Manual LUCI Re-runs

• Due to GitHub App permission policies, third-party check runs (such as LUCI checks created by flutter-dashboard) cannot be re-run via the GitHub API.
• *Action*:
• Print the exact LUCI Buildbucket link (e.g., https://cr-buildbucket.appspot.com/build/<build_id>) for the failing check.
• Instruct the user to open the URL and click Retry Build on the LUCI page.
• If a check continues to fail after manual retries, inspect the failure logs (gh pr view <number> --repo flutter/flutter or flutter-pr-checks-finder) and summarize the failure for the user.

5. Stale Branch Updates, CICD Label & Token Scope

• If a PR branch is out of date with master (including when the base commit is >7 days old):
• Always update the branch using gh pr update-branch <number> --repo flutter/flutter before attempting to add autosubmit.
• Re-applying the CICD Label:
• After updating a branch with gh pr update-branch (or when shepherding a PR that has not run CI), the CICD label is often stripped or required to start the CI checks on the updated commit.
• Always check if the CICD label is present after a branch update, and re-apply it if missing:

    gh pr edit <number> --repo flutter/flutter --add-label CICD

• Stale Token Scope Error: If updating fails due to workflow file permissions (ERROR: ... lacks the "workflow" scope), instruct the user to refresh their CLI scope:

  gh auth refresh -h github.com -s workflow

6. Target Branch Correction & Merge Conflicts

• Dismissed Reviews Warning: Changing the target branch of a PR often causes GitHub to automatically dismiss existing approvals. Alert the user if the target branch changed so they can re-approve on GitHub.
• Merge Conflicts: If a PR has conflicts (MERGEABLE is CONFLICTING), notify the user so the author can resolve them.