Burst Bug Hunter

Burst Bug-Hunter (generic engine)

Why

Interactive step-by-step CLI driving costs one LLM turn per action — a long hunt is mostly model round-trips, not browser work. This flips the default: the unit of work is a whole multi-step script (a "burst") that runs unattended and returns one structured result. You observe at burst boundaries, not per action. Typical effect: ~8× fewer model turns per feature vs step-by-step.

Two modes

• Verify with bursts (default) — you HAVE the app model; confirm expected behavior fast.
• Explore step-by-step (rare) — you DON'T have the model yet; build it. Crystallize whatever flows you discover into the repo's verb library so the next agent inherits them (see Answering "doesn't the agent need app knowledge?" below).

The engine (this skill, assets/, app-agnostic)

• driver-server.mjs <app-url> <workdir> [config.json] — opens the app ONCE, keeps it warm, runs submitted job scripts, enforces a hard deadline (<workdir>/deadline epoch secs → all non-shutdown jobs rejected after). Every result carries remainingMs.
• start-hunt.sh <workdir> <app-url> [config.json] — boots one warm server, waits ready.
• vrun — submit a job and block for the full result (VDRIVE=<workdir> selects the server). Also: vrun --reset, vrun --inline 'CODE', vrun --finding '{json}' (append a finding line without a browser round-trip).
• example-burst.mjs — copy/adapt template: a defensive burst that records a per-step trace so a wrong prediction fails at a NAMED step (cheap to fix) instead of derailing.

The contract — what the REPO provides (nothing app-specific lives in this skill)

Put these in the repo (convention: .hyper-sprint/), and pass the config to the engine:

• A bootable app URL — build/serve the app and yield a file:///http:// URL. A repo boot script (e.g. .hyper-sprint/burst-boot.sh <args> <outdir> printing the URL) is handy.
• config.json with:
  • readyExpr — JS predicate, true when the app is booted (default document.readyState==='complete').
  • resetExpr — JS run IN THE PAGE to reset to initial state without reload (optional; falls back to page.reload()). Prefer an in-memory reset hook the app/harness exposes.
  • initScript — path (relative to the config file) to JS injected BEFORE load (optional; e.g. a storage polyfill).
  • viewport — optional.
  • verbs — path to the repo's verb library (page objects) that bursts import.
• A verb library — stable, self-observing verbs (each waitForFunctions its own post-condition, throws a NAMED error if the model is wrong). Authored by whoever knows the app — ideally reused straight from the implementer's own drive/test scripts.

Hunter protocol (what a hunt sub-agent does)

1. export VDRIVE=<your workdir>; confirm warm: [ -f $VDRIVE/ready ].
2. Work in bursts: write job.mjs (export async function run(page, ctx){…}, importing the repo's verbs by absolute file:// path), then assets/vrun job.mjs. ctx.reset() / vrun --reset = instant known-initial state. ctx.shot(name) screenshots.
3. Make bursts defensive (per-step trace); on a wrong prediction read failedAt, fix, re-run.
4. Append every finding immediately: vrun --finding '{"sev","title","repro","observed","expected"}'. Don't hold findings to the end — the window can close mid-hunt.
5. Hunt non-stop until the deadline; use each result's remainingMs to pace. When a job returns {"ok":false,"error":"DEADLINE…"} the window is closed — stop, write nothing more.
6. Classify in-scope defect vs out-of-scope/pre-existing. Report literal observed output.

Orchestrator: launch + time-box + eval

URL=$(bash <repo-boot-script> <args> <outdir>)                 # repo-specific boot → URL
bash assets/start-hunt.sh /tmp/hunt-A "$URL" <repo>/config.json  # one warm server per hunter
python3 -c 'import time;print(time.time()+180)' > /tmp/hunt-A/deadline   # hard cap
# spawn hunter sub-agents (VDRIVE + feature + the repo's verbs path), then DON'T wait:
# each server writes <workdir>/stats.json (jobs, totalMs, remainingMs) and logs every job.
# At the deadline, read stats.json + findings.jsonl and eval — kill, don't wait.

Screenshots for free → the sprint report

Verification and documentation share one pass. Have each verifier ctx.shot("<cr>-after-<label>") at its proof state — those PNGs are exactly the "after" images the hyper-sprint Markdown report needs (see the hyper-sprint skill's references/sprint-archive.md). "Before" images = the same tagged bursts run against a warm render built from the base commit. No separate capture step.

Answering "doesn't the agent need app knowledge to write bursts?"

Yes — but as a one-time inherited asset, not a per-burst prediction: (1) the implementer authors the verb library (it already wrote drive scripts); (2) verbs self-observe (waitForFunction), so the agent predicts the sequence, not exact DOM/timing; (3) stable test-ids are the app's published driver contract — snapshot them instead of reading source; (4) wrong predictions fail named + cheap, so the model improves by one correction. Explorer output must compound back into the verb library, or every agent re-pays the "predict from scratch" tax.