Task
Turn a bug report into a minimal diagnostic plan.

Instructions
Diagnose [BUG REPORT] in [STACK]. First restate the observable symptom and expected behavior. List competing hypotheses, the cheapest discriminating check for each, required logs, and a minimal reproduction. Do not implement a fix until the failing behavior is isolated.

Expected output
Symptom, hypotheses, ordered checks, reproduction, and evidence needed.

Checks
- Expected behavior is explicit.
- Checks distinguish hypotheses.
- No fix is claimed without evidence.