qa-investigate

name	qa-investigate
description	[QA Method] Bug investigation: reproduce, isolate root cause, gather evidence, common VC patterns.
argument-hint	bug description | VCST-XXXX

/qa-investigate — Bug Investigation Flow

Investigate a suspected bug using a structured 5-phase process: Reproduce → Isolate Layer → Gather Evidence → Identify Root Cause → Document & Hand Off.

Usage

/qa-investigate Payment form not submitting on checkout
/qa-investigate VCST-1234
/qa-investigate Flaky test in Suite 04 — cart total sometimes shows $0

Execution

1. Read the investigation flow: Load bug-investigation-flow.md from this skill folder for the full process, decision tree, and common VC patterns (P1–P8). For the operational evidence-capture pass and the root-cause worksheet, also load evidence-and-root-cause.md (the runnable companion) — this is where the depth lives.

   Scaffold the evidence package up front so every artifact has one home and nothing is missed:

   npx tsx scripts/regression/bundle-evidence.ts VCST-XXXX [--sprint=Sprint-current] [--browser=chrome] --symptom="…"
   

   It resolves TEST_ENV, pre-fills the env header, creates screenshots/ network/ console/ har/ source/, and writes evidence-index.md (manifest with the mandatory-slot + trace-ID checklist) and root-cause.md (the worksheet).

2. Resolve TEST_ENV FIRST (bug-investigation-flow.md §1):

   • Determine the env (user-named → ticket field → default vcst); state it explicitly
   • Resolve FRONT_URL / BACK_URL / STORE_ID / ENV_RISK; run /qa-env-check endpoints to confirm health
   • Discover the env's App Insights resource(s) by matching the active URLs (don't assume a fixed name; some envs have none)
   • Capture platform + theme versions for the report header

3. Reproduce the bug:

   • If a JIRA ticket is provided, fetch details via Atlassian MCP
   • Extract exact URL, user action, expected vs actual behavior
   • Attempt reproduction using the appropriate browser (Playwright MCP) on the resolved env
   • Try at least 3 reproduction attempts before declaring "cannot reproduce"

4. Isolate the layer, then name the fix target (bug-investigation-flow.md §3):

   • Start at the network tab — the API response tells you which layer owns the bug
   • Frontend (DOM/JS) → Chrome DevTools console + network; Backend (REST/xAPI) → response codes, GraphQL errors, health; Infra → CORS/CDN/SSL/DNS; Data → account/inventory/pricing state
   • Map the owning layer → repoKind → exact repo (§3 Step 5 + §8): vc-frontend / vc-module-x-* / vc-module-* / vc-platform, resolved via module-suite-map.md + fix-repos.json. Determine layer/module/frontend/platform precisely — never hand off a vague "backend bug".

5. Gather ALL logs & evidence — run the ordered capture pass (evidence-and-root-cause.md Part A; bug-investigation-flow.md §4 + §9):

   • Capture on the reproducing run, in order, into the package subfolders — not afterward.
   • Mandatory: failure-state screenshot + DOM snapshot, network request list + the failing request's body, console messages, HAR, systeminfo versions.
   • Capture the operation/trace ID DURING repro (Request-Id/traceparent on the failing request) and write it into evidence-index.md — it's the join key for App Insights and is unrecoverable once you navigate away.
   • Application Insights — mandatory whenever any REST/xAPI/Admin/job layer is involved: correlate the trace ID, read the exception chain + dependency failures.
   • "GraphQL wrong" is not a layer verdict until you've cross-checked REST (evidence-and-root-cause.md Part A row 9).

6. Identify root cause — fill the worksheet, don't just pattern-match (evidence-and-root-cause.md Part B → root-cause.md). Pattern-matching P1–P8 gives a hypothesis; the worksheet turns it into a conclusion: every claim cites a captured artifact (trace ID / response body / source line), the lowest failing layer is proven not assumed, and at least the two obvious alternatives (by-design, data drift) are ruled out. Name a repoKind/repo only at MEDIUM+ confidence — LOW confidence hands off "symptom + layer + what's left", never a guessed repo. Pattern reference:

   • P1: Module version incompatibility
   • P2: Stale Elasticsearch index
   • P3: Authorization scope — orphaned organization
   • P4: SDK/integration serialization
   • P5: Pre-authentication API call
   • P6: External resource URL assumption
   • P7: Duplicate GraphQL queries
   • P8: Hangfire job failure

7. Dig into the source code — answer WHERE, then WHEN & WHY (bug-investigation-flow.md §8). When browser/log evidence isn't enough to explain the behavior, read the actual code via GitHub MCP (read-only):

   • WHERE (§8A backend vc-module-* / §8B frontend vc-frontend): search_code for the controller/service/resolver or page/composable/store, trace the logic chain, and decide by-design vs. defect.
   • WHEN & WHY (§8C — regression archaeology): for any "used to work" / post-deploy / version-skew symptom, bracket the good→bad window (§1 + §9), walk list_commits on the suspect path, diff the method across good/bad refs, and open the introducing PR (get_pull_request) to recover what the change intended. Confirm the diff actually explains the symptom — correlation ≠ causation.

8. Document and hand off:

   • Gate first: run npx tsx scripts/regression/bundle-evidence.ts VCST-XXXX [--sprint=…] --check. A clean PASS (all mandatory slots filled + alternatives ruled out) is the bar before writing the report; an INCOMPLETE means go back and capture.
   • Write bug report using templates in skills/qa-defect/defect-report-templates.md — reference the package artifacts, don't inline them (reports.md §8)
   • Include the env header (§1) and the Fix Routing block (owning layer + repo + repoKind, per qa-bug.md Step 4) so /qa-fix Gate 1 can confirm rather than re-derive
   • For regressions, add the Regression block (§8C Step 4): introducing commit/PR, first-bad & last-good versions, why it broke, revert-safe vs. fix-forward
   • Save to reports/bugs/
   • Optionally create JIRA ticket via Atlassian MCP

Rules

• Resolve TEST_ENV first — every URL/credential/App Insights resource is per-env; discover the App Insights resource by matching the active URLs, never hardcode an env name
• Never file a bug you cannot reproduce
• Run the ordered capture pass (evidence-and-root-cause.md Part A) into the bundled package; the trace/operation ID is mandatory for any server-side bug and must be grabbed during repro — it's unrecoverable later
• bundle-evidence.ts --check must PASS before filing — all mandatory evidence present and worksheet alternatives ruled out
• Every root-cause claim cites a captured artifact; name a repo only at MEDIUM+ confidence (evidence-and-root-cause.md Part B)
• Determine layer/module/frontend/platform precisely; carry it into the Fix Routing block
• For any "used to work" / post-deploy / version-skew symptom, read the source (§8) to pin where, then do regression archaeology (§8C) to pin when & why — name the introducing commit/PR only when its diff actually explains the symptom (correlation ≠ causation)
• If cannot reproduce after exhausting checklist, document the failed attempt and escalate
• Distinguish flaky behavior from real bugs (see decision tree in supporting file)