RFC: Proposal for autoclose option for non-compliant PRs

Following up on the discussion in #31679 about low-effort contributions (like ai-generated with low human supervision), @lucyleeow and me worked out an idea: We would like to propose introducing an autoclose option for PRs that gets triggered when setting an "autoclose" label that can be removed if the PR is improved.

The idea is to provide a structured way to handle PRs that don't yet meet our contribution standards and facilitate the reviewing process. This will be transparent and fair for new contributors.

**Suggested process**
1. A contributor opens a PR that looks low-effort, fly-by, not supervised ai-generated, or otherwise not yet ready for review.
2. A reviewer sets an "autoclose" label. This would automatically add a polite, standardised comment explaining:
    - The PR will be autoclosed after _n_ weeks (e.g. _4_).
    - A list of common quality issues (similar to what we used in #31822) that outlines what the contributor needs to address in order to avoid the PR being autoclosed (can contain links to the docs and the FAQs where we explain those things in detail).
    - An encouragement to comment on the PR and ping the person who set the "autoclose" once they believe they have met the quality standards and addressed the issues, or when they struggle or need clarification in a specific point.
    - A note that reviewer time is limited and we cannot provide detailed guidance.
3. Possible outcomes:
    - If the author doesn't respond or pushes commits that don't address the issues → PR is autoclosed after the timeout.
    - If the author states problems → reviewers can offer guidance at their discretion, based on capacity and fit.
    - If the author makes the required improvements:
        - ideally either the reviewer who set the label or the person on triage removes the label, which stops the autoclose action, and the PR can be reviewed and move forward as usual
        - in some cases (hopefully not too often) we might miss the deadline and the author would need to open a new PR (that's a downside on applying an the autoclose policy)

**Benefits**
- For maintainers: avoids the implicit obligation to fully review low-quality PRs and allows to focus on genuine contributions.
- For contributors: sets clear expectations from the start, and thoughtful contributors benefit because reviewers have more time for their PRs. 
- For the project: helps keep the PR queue manageable and signals that quality and preparation are expected.

The key point is that this wouldn't reduce our support for new contributors. It only shifts the expectation: authors are responsible for bringing their PRs to a reviewable state, and reviewers can decide how much help to give along the way.

**Technical feasibility**
This should be achievable with a GitHub Action, similar to those used in many open source projects to autoclose stale issues or PRs, but triggered by a label instead of inactivity.

COMMENT:
> One thing to ponder: is pinging the person who put the label the best idea? We don't want to burden the person who puts in the work of labelling things (just because you label something doesn't mean you care about it) and in general making something rely on one person isn't good because they go on holiday/illness/etc. But I'm not sure that suggesting to ping the whole team is better. So I have no good solution :-/

I fully agree. Pinging the whole team is something we should avoid at all costs. Pinging the person who set the label maybe as well. We could only ask the contributor to comment on the PR (not mention to ping, though many will do anyways), but then how to make sure their update is seen and reviewed? Does setting a label subscribe you to this PR? If the time is ticking for this PR, there should be a fair chance to have it checked by us a second time if the author reacts to our request to fix the quality.

This is why I was stressing that we should communicate that we are unfortunately short in reviewing time and there might be no possibilty for us to lead people through the process of making their PR reviewable. And the obligation of the person who put the label would be only to decide whether to remove the label, without any obligation to write down all the reasons of why this PR is still not meeting the standards. And without the obligation to review it in case it meets the standards, of cause.

> That sounds a lot less complicated to build than what I imagined

Cool, I'm super happy to work on that, if this is how the discussion turns out.

Labels: Needs Decision, RFC