From tw93-claude-health
Diagnoses root causes of errors, crashes, unexpected behavior, and failing tests before applying fixes using hypothesis-driven process with evidence.
npx claudepluginhub tw93/wazaThis skill uses the workspace's default tool permissions.
Prefix your first line with 🥷 inline, not as its own paragraph.
Enforces scientific-method debugging loop (Observe→Hypothesize→Experiment→Conclude) for non-trivial bugs like crashes, flaky tests, performance regressions, or CI failures.
Performs root cause analysis for bugs by tracing errors through code, analyzing stack traces, forming and testing hypotheses, then hands off to fix. Auto-triggers on stack traces.
Guides root cause debugging for bugs, test failures, and unexpected behavior. Enforces reproduce-investigate-hypothesize-fix process with evidence before fixes. No guessing.
Share bugs, ideas, or general feedback.
Prefix your first line with 🥷 inline, not as its own paragraph.
A patch applied to a symptom creates a new bug somewhere else.
Do not touch code until you can state the root cause in one sentence:
"I believe the root cause is [X] because [evidence]."
Name a specific file, function, line, or condition. "A state management issue" is not testable. "Stale cache in useUser at src/hooks/user.ts:42 because the dependency array is missing userId" is testable. If you cannot be that specific, you do not have a hypothesis yet.
When these surface, stop and re-examine:
| What you're thinking | What it actually means | Rule |
|---|---|---|
| "I'll just try this one thing" | No hypothesis, random-walking | Stop. Write the hypothesis first. |
| "I'm confident it's X" | Confidence is not evidence | Run an instrument that proves it. |
| "Probably the same issue as before" | Treating a new symptom as a known pattern | Re-read the execution path from scratch. |
| "It works on my machine" | Environment difference IS the bug | Enumerate every env difference before dismissing. |
| "One more restart should fix it" | Avoiding the error message | Read the last error verbatim. Never restart more than twice without new evidence. |
When these appear, the diagnosis is moving in the right direction:
| What you're thinking | What it means | Next step |
|---|---|---|
| "This log line matches the hypothesis" | Positive evidence found | Find one more independent piece of evidence to cross-validate |
| "I can predict what the next error will be" | Mental model is forming | Run the prediction; if it matches, the model is correct |
| "Root cause is in A but symptoms appear in B" | Propagation path understood | Trace the call chain from A to B and confirm each link |
| "I can write a test that would fail on the old code" | Hypothesis is specific and testable | Write the test before applying the fix |
Do not claim progress without observable evidence matching at least one of these signals.
sw_vers / node --version / grep first. No results = re-examine the path.Activate when the symptom is "used to work, now broken" or "broke after an update". Random-walking forward from the current state wastes context and produces random fixes.
Flow:
last-known-good: use the most recent tag where the behavior was correct (git tag --sort=-version:refname | head -5). Do not use a date or a raw SHA as the anchor.git bisect start, git bisect bad (current), git bisect good <tag>. Let bisect drive; do not jump ahead.Add one targeted instrument: a log line, a failing assertion, or the smallest test that would fail if the hypothesis is correct. Run it. If the evidence contradicts the hypothesis, discard it completely and re-orient with what was just learned. Do not preserve a hypothesis the evidence disproves.
| What happened | Rule |
|---|---|
| Patched client pane instead of local pane | Trace the execution path backward before touching any file |
| MCP not loading, switched tools instead of diagnosing | Check server status, API key, config before switching methods |
| Orchestrator said RUNNING but TTS vendor was misconfigured | In multi-stage pipelines, test each stage in isolation |
| Race condition diagnosed as a stale-state bug | For timing-sensitive issues, inspect event timestamps and ordering before state |
| Reproduced locally but failed in CI | Align the environment first (runtime version, env vars, timezone), then chase the code |
| Stack trace points deep into a library | Walk back 3 frames into your own code; the bug is almost always there, not in the dependency |
| Worked when launched from app, broke when opened via file association / drag-drop / deep link / external proxy | Reproduce using the exact entry point the user described. App-internal init differs from cold-launch-with-file init; state may not be ready when the document arrives. |
Root cause: [what was wrong, file:line]
Fix: [what changed, file:line]
Confirmed: [evidence or test that proves the fix]
Tests: [pass/fail count, regression test location]
Regression guard: [test file:line] or [none, reason]
Status: resolved, resolved with caveats (state them), or blocked (state what is unknown).
Regression guard rule: for any bug that recurred or was previously "fixed", the fix is not done until:
Symptom:
[Original error description, one sentence]
Hypotheses Tested:
1. [Hypothesis 1] → [Test method] → [Result: ruled out because...]
2. [Hypothesis 2] → [Test method] → [Result: ruled out because...]
3. [Hypothesis 3] → [Test method] → [Result: ruled out because...]
Evidence Collected:
- [Log snippets / stack traces / file content]
- [Reproduction steps]
- [Environment info: versions, config, runtime]
Ruled Out:
- [Root causes that have been eliminated]
Unknowns:
- [What is still unclear]
- [What information is missing]
Suggested Next Steps:
1. [Next investigation direction]
2. [External tools or permissions that may be needed]
3. [Additional context the user should provide]
Status: blocked
Activate when: "PDF looks wrong", "page break issue", "font not rendering", or broken PDF output
Diagnosis checklist:
rgba() causes double-rectangle bug (use solid hex), page-break-inside: avoid ignored (use explicit breaks)@media print rules, @page margins, orphan/widow controlStatic analysis first (CSS review), then reproduce if needed.