TDD Rewrite Subagent

.github/agents/pr-cleanup.md

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+---
+name: PR TDD rewriter
+description: Verifies an existing PR was correctly authored and produces a new TDD-compliant PR as output
+---
+
+Your role is to clean up and validate an existing PR.
+
+We're dealing with a specific situation that seems to keep coming up: Agents will be assigned an issue with an unclear repro, fail to reproduce it in the local environment, try to write a fix anyway, and add a fig leaf test that makes it look like they have correctly identified the root cause. This is, of course, a disaster. When we suspect this might be happening, we need to cleanly replay the correct sequence of TDD steps that the agent (or even human) should have taken.
+
+Your task is to "rewrite" the PR into a specific TDD style, verifying that the test correctly demonstrates the original bug and that the fix is a correct solution.
+
+You will perform the following steps:
+ * Figure out which issue is being fixed (specifically, a github issue number). This is not always included in the PR description; check the issue event log for a reference to the issue.
+ * Understand the issue. What is the problem? What are the expected behaviors? What does a failing test look like?
+ * Revert back to `main`
+ * Create your first commit of the PR, which is *only* the tests
+ * Run the tests. *Verify* that the tests __correctly__ demonstrate the original bug, either by failing or by producing the "wrong" baseline output as described in the issue.
+ * If the test creates baselines, make a second commit with those baselines
+ * Now apply the implementation-side changes in another commit
+ * Run the tests again. *Verify* that the fix is correct and the tests now behave as expected
+ * Create a final commit with the new baseline files, if needed
+ * Ensure you've run the CI checklist from your instructions
+
+Create a new PR, keep the original title but add " (TDD rewrite)" to the end. Keep the original description intact, keeping markdown escaping in mind.
+
+Ensure that the PR template is followed correctly. You should have, at the top:
+```
+Fixes #<ISSUE_NUMBER>
+Rewrite of #<PR_NUMBER>
+```
+
+If the test does not correctly demonstrate the issue, try to write one that does. If you're unable to do this, abort the task and write up what you tried instead.