Making the phpstan-drupal playground work for agents

The useful part

You paste PHP, run PHPStan with phpstan-drupal against a real Drupal core install, and share the result link in an issue. The bugs were small, individually boring, and always someone else's turn on my list. What finally cleared them was working through them with an agent, which is also how the rest of this post happened.

How it works

• The HTML shell served for /r/ carries a comment and a block pointing there, so an agent that fetches a share link and finds nothing can still find its way to the data.
• When they differ, the Markdown shows both sets, and the agent knows the bug was probably already fixed before it starts digging.
• It never quite worked right, and I never got around to fixing it.
• JSON works for an agent, but it has to correlate line numbers with the code on its own, and it has to notice that tabs, the errors saved when the link was created, and upToDateTabs, the same code re-run...

What to take from it

Send "saveResult": false while it narrows the snippet down, then one final run with the default to get a link worth sharing. Two things I wanted: A reporter tells their agent, "push this reproduction to the playground," and gets a link to paste into the issue. I hand my agent a share link, and it reads the code and the error, then goes to fix the bug.

Example or evidence

• See https://phpstan-drupal.mglaman.dev/llms.txt for the endpoints and request format.
• Results are public and stored forever, which is the point for a bug report and the wrong thing for an agent iterating on a reduction.
• Render a share link as Markdown GET /result?id= already returned the saved code and errors as JSON, plus a fresh re-run against the current runner.
• curl -s "$BASE/result?id=e8500ee1-9159-4fea-a49b-27a46112101d&format=markdown" And the result # phpstan-drupal playground result.

Details worth keeping

The site is a Svelte app, so fetching a share link returned an empty. The API hostname was only discoverable by reading the source. Tell the agent where the API is The site now serves /llms.txt.

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