Report Codespaces prebuild failures in GitHub issues

[Copilot]

Adds failure reporting for monitored workflows, initially Codespaces Prebuilds. Each failure creates an issue linking failed jobs and prompting @github/primer-engineering.

Changelog

New

• Workflow monitor with an extensible workflow list.
• Failure issues titled “Investigate GitHub workflow failure.”
• Issue body listing the failed workflow and linked jobs.

Changed

• None.

Removed

• None.

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; CI-only change with no published package impact.

Testing & Reviewing

• Review the workflow trigger, scoped permissions, and generated issue format.

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Latest commit: fefcc2f

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[joshblack]

@copilot let's just have it make a contextual workflow and the title should include the workflow name e.g. Investigate {workflow_name} workflow failure. It should not duplicate issues if one already exists, instead it should update the issue with the latest failure. It should also close any open failure issues for the workflows if they pass.

[Copilot]

@copilot let's just have it make a contextual workflow and the title should include the workflow name e.g. Investigate {workflow_name} workflow failure. It should not duplicate issues if one already...

Implemented in 28cc6ee and finalized in 44672e3. Issues now use Investigate {workflow_name} workflow failure, update the existing workflow issue with the latest failure, and close open failure issues after a successful run.

[joshblack]

@copilot split this into two steps:

• create-or-update-issue if the workflow failed
• close-issue if the workflow succeeded

apply appropriate logic to each

[Copilot]

@copilot split this into two steps:

• create-or-update-issue if the workflow failed...

Implemented in 3dd27f1. Failure runs now use create-or-update-issue, while successful runs use the independently gated close-issue job.

[joshblack]

@copilot apply review suggestions. Also investigate if we can assign copilot automatically to the issue to try and fix it

[Copilot]

@copilot apply review suggestions. Also investigate if we can assign copilot automatically to the issue to try and fix it

Addressed in f8490ca. I applied the review feedback by narrowing issue lookup to matching failure issues, avoiding issue flapping when a newer run is still pending, and formatting failed-job links safely. I also investigated Copilot assignment and added a best-effort copilot assignment when creating/updating the issue; if Copilot assignment isn't enabled for the repository, the workflow logs a warning instead of failing.