[plan] Fix update-discussion API error when targeting explicit discussion_number

[github-actions]

Objective

Investigate and fix the API error that occurs when update-discussion handler is called with an explicit discussion_number in the message.

Context

From issue #23283 (smoke test findings): When the agent hardcoded discussion_number: 45 (because there was no triggering discussion in workflow_dispatch context), the API call failed with:

ERR_API: update discussion #45 failed (attempt 1)

The resolveDiscussionNumber() function in update_discussion.cjs correctly picks up the explicit number when item.discussion_number !== undefined, but the downstream GraphQL mutation fails.

Approach

1. Open actions/setup/js/update_discussion.cjs and find the GraphQL mutation used to update a discussion
2. Add better error logging to capture the full API response / error detail
3. Check whether the failure is due to:
   • Missing/wrong permissions in the GitHub token
   • Incorrect GraphQL mutation variables (field names, types)
   • Rate limiting or authentication issues
   • The discussion being in a closed/locked state
4. Fix the root cause and improve error messages to make failures more diagnosable in future runs

Files to Modify

• actions/setup/js/update_discussion.cjs — fix GraphQL mutation and/or improve error handling/logging

Acceptance Criteria

• The update-discussion handler successfully updates a discussion when given an explicit discussion_number
• Error messages include enough detail to diagnose failures (API response body, status code)
• The smoke test run passes for update-discussion when the agent provides a valid discussion_number

References

• Issue Safe-outputs discussions smoke test: update-discussion API error and close-discussion label enforcement #23283 (smoke test findings)
• Run: https://github.com/github/gh-aw-mcpg/actions/runs/23670080887
  Related to Safe-outputs discussions smoke test: update-discussion API error and close-discussion label enforcement #23283

Generated by Plan Command for issue #23283 · ◷

• expires on Mar 30, 2026, 1:55 AM UTC