Generate PR description

Generate the PR description without wrapping it in a code fence. Never post or edit it unless authorised under 4. Decide whether to update the PR.

1. Establish the change

• If given a PR number or URL, inspect its metadata, commits, and full diff.
• Otherwise, inspect the PR associated with the current branch. If none exists, compare the current branch with the repository's default branch, including committed changes only.
• Read enough surrounding code and documentation to understand behaviour rather than merely restating file changes.
• Derive motivation from reliable context such as the PR, linked issue, commit messages, or repository documentation. Never invent motivation. If it remains unclear, ask one focused question before drafting.

2. Select content

What

Describe outcomes and observable behaviour, not the editing process.

• Use 1–5 bullets; target at most 15 words each.
• Keep one distinct change per bullet and group closely related implementation details.
• Prefer product or user-facing behaviour over file names and implementation mechanics.
• Include internal changes only when they are the substance of the PR or materially affect maintainers.
• Omit tests, formatting, generated files, routine wiring, and incidental refactors from feature or fix PRs.
• If the PR only changes tests, describe those test changes.
• Do not claim behaviour unsupported by the diff.

Why

Write at most one extremely succinct sentence explaining the problem, need, or motivation. Do not repeat the What section.

Notes

Omit this section by default. Add it only when critical understanding requires one of:

• stating that something was deliberately not done;
• explaining why something was skipped;
• providing essential context not suitable for What or Why.

Use no more than three succinct bullets. Do not add routine test, deployment, or implementation commentary.

3. Output

Use this exact structure, omitting ### Notes entirely when unnecessary:

## Description

### What? What has changed/is the new behaviour?

This PR:

- <succinct change>
- <succinct change>

### Why? Motivation and context

<extremely succinct context>

### Notes

- <succinct critical note>

Before responding, remove redundancy, implementation trivia, unsupported claims, and every non-essential word.

4. Decide whether to update the PR

If no existing PR was resolved, do not offer an update or create a PR but stop instead.

Otherwise, first resolve this decision:

Are you running in auto mode? Yes or no.

Choose Yes only when auto mode is explicitly indicated by the current agent or runtime. Never infer it. If its status is unclear, choose No.

If Yes

Update the resolved PR with the generated description without asking for further approval. Auto mode provides authorisation for this update.

If No

After presenting the description, ask:

Would you like me to update PR #{number} with this description?

Do not update the PR unless the user then gives explicit authorisation. Invoking this skill, requesting a description, prior approval, or implied approval does not count. If the user declines or does not answer, leave the PR unchanged.

Updating

Once authorised through either branch:

• Prefer GitHub CLI (gh) when available.
• Update only the resolved PR's body, preserving the generated description exactly.
• Use gh pr edit {number} --body-file {temporary-file} rather than interpolating the description into shell arguments.
• If gh is unavailable, use a safe available GitHub integration. If none locally available, report that the update could not be made.
• Delete any temporary file afterwards.
• Confirm which PR was updated; never merge, close, or otherwise modify a PR.