/hunt

name: hunt
description: "Finds root cause before applying fixes for errors, crashes, regressions, failing tests, broken behavior, and screenshot-reported defects. Use when users report in any language errors, crashes, broken behavior, regressions, failing tests, screenshot evidence, or something that used to work and now fails. Not for code review or new features."
when_to_use: "排查, 查查, 报错, 崩溃, 不工作, 不对, 跑不通, 以前是好的, 回归, 截图回归, 判断错误原因, 判断为什么报错, 反复修不好, debug, regression, used to work, broke after update, why broken, not working, what's wrong, fix error, stack trace"
dispatch_intent: "Error, crash, regression, screenshot-reported defect, test failure, stale cache, runtime boundary, why broken"

Hunt: Diagnose Before You Fix

Prefix your first line with 🥷 inline, not as its own paragraph.

A patch applied to a symptom creates a new bug somewhere else.

Outcome Contract

• Outcome: the root cause is identified before any fix is applied.
• Done when: one sentence explains the cause, every observed symptom fits it, and the fix or handoff is verified against a reproducible check.
• Evidence: source trace, repro command or UI path, logs or state, targeted test/build output, and runtime evidence for UI or native defects.
• Output: root cause, fix or handoff, verification result, and any unswept sibling risks.
• Authorization: "diagnose", "investigate", "why", "look into", "排查", "看看", or equivalent is report-only. Apply a fix only when the current turn explicitly asks to fix, change, implement, or optimize; root-cause proof is still required first.

**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.

Diagnosis Signals

Hypothesis quality gate: the hypothesis must explain every observable symptom, not just the one reported first; partial coverage is a symptom-level guess, not a root cause. A symptom the reporter waves off as unrelated is still a symptom the hypothesis has to cover. For timing-dependent issues (flicker, intermittent failure, race), reproduce reliably before diagnosing.

Rationalization smells: "I'll just try this" = no hypothesis, write it first. "I'm confident" = run the instrument that proves it. "Probably the same issue" = re-read the execution path from scratch. "It works on my machine" = enumerate env differences before dismissing. "One more restart" = read the last error verbatim; never restart more than twice without new evidence.

Durable Context Preflight

See [references/durable-context.md](references/durable-context.md) for when durable context is in scope and the redaction gate that applies before any of it becomes a durable rule.

For `/hunt`: durable context is hypothesis fuel only, and current code, logs, and repro evidence override memory. It never replaces a fresh root-cause sentence or a reproducible symptom list.

Fix Scope Discipline

If the bug needs a prerequisite refactor (e.g. a shared interface must change), state why it is necessary and check the authorized scope. Continue if that work is covered; ask before expanding the scope or choosing an unresolved behavior tradeoff. Keep unrelated refactors separate.

Bisect Mode

Activate when: "以前是好的", "之前是好的", "used to work", "上一次提交还是对的", "broke after update", or the user remembers a specific good commit or version.

• Protect the user's worktree first: `git status --short --branch -uall`. Any modified, staged, or untracked files mean no bisect in the current checkout: run it in a temporary detached worktree and remove that worktree when done. If a temporary worktree is impossible, stop and ask for explicit cleanup/stash approval.
• If the last-good version is only a few releases back, `git diff <last-good>..HEAD -- <suspect path>` and read the delta first. The regression is usually visible there at a fraction of a bisect's cost; fall through to bisect only when the diff is too large or the culprit is not obvious.
• Bisect only with a non-interactive pass/fail command defined up front, and keep the bookkeeping in git (`git bisect good/bad`), including when you test a suspect commit directly. When it names the culprit, read only that diff down to the specific line, then run `git bisect reset` before removing the temporary worktree.

Repeated Regression / Screenshot Reference Mode

Activate when the user says the same issue is still wrong after a fix, provides a "good" screenshot/version/file, or describes a visual result as previously correct.

Treat the reference as evidence, not decoration: list every reported and visible symptom in the user's concrete words; identify the reference oracle (last-good commit, old build, fixture, screenshot, described expected state); define the pass/fail check before editing; then name the exact current-vs-reference delta. Do not generalize a visual defect into "style polish" when the evidence points to a broken render, race, font pipeline, or state path.

If the issue is purely subjective UI taste, route to `/ui`. If it is rendering, state, timing, build output, font generation, or a regression from a known-good version, stay in `/hunt`.

Scope Blast Mode

Activate after fixing a root-cause pattern, before declaring the bug done; also when the user says "举一反三", "举一反三深入看看", or "其他地方有没有同样问题". The same shape often hides in N other places; one local fix that ignores the blast leaves N - 1 bugs in the tree.

Extract the pattern signature (the specific function, regex, API call, CSS selector, lock acquisition, validation skip, or input boundary that produced the bug) and `grep -rn` it across the repo, excluding generated dirs, build output, and vendored deps; for class-of-bug patterns ("any handler missing th