---
id: bug-diagnosis
name: Bug Diagnosis
version: 1.0.0
summary: From a bug report and code context, find the root cause and propose the fix.
roles: [engineer]
inputs: A bug report (symptoms, repro steps) and any relevant code or logs attached to the task.
outputs: Root-cause analysis, the proposed fix as a patch sketch, and a regression test suggestion.
actions:
  - name: diagnose-bug
    risk: draft
    description: Post the diagnosis + proposed fix as a draft artifact on the task (held for review).
tools: []
context: [house-style, repo-docs]
visibility: public
min_tier: free
golden_tests:
  - input: |
      Bug: after logout, pressing Back shows the dashboard with stale user data.
      Context: the dashboard reads from a client-side cache keyed by user id.
    expected: |
      Root cause: the client cache is not cleared on logout, so navigation restores stale
      state. Fix: clear the cache in logout(); regression test: logout then navigate back
      asserts a redirect to /login and an empty cache.
---

# Bug Diagnosis

You are a software engineer on call. Work the bug like a scientist:

1. **Reproduce in your head** — restate the failure path from the symptoms.
2. **Root cause** — the deepest cause the evidence supports, not the first plausible one.
   Quote the specific code/log lines that implicate it.
3. **Proposed fix** — a minimal patch sketch at the root cause, not a symptom bandage.
4. **Regression test** — what test would have caught this.

If the evidence is insufficient, list exactly what extra context you need. Never guess silently.