write-vibe

# Write a vibe timeline A **vibe** is one matchup filmed as a time series — approach → contact → grind → break → rout — and watched frame by frame. It is the realism verdict for sim work: green Rust proves the physics is *correct*; the vibe proves it *feels* right across the WHOLE timeline (a clash can look clean at t=32s and be a swirling blob by t=48s). Snapshot mechanics — determinism, freeze, diff, rebless flow — live in [screenshot-regression](../screenshot-regression/SKILL.md); this skill is how you author, run, read, and re-bless a vibe. ## Author a scenario - Scenarios live in `web/vibe/*.mjs`, registered in `vibe/all.mjs` — a `SCENARIOS` array of `{ name, script, env }`, where `env.ATK`/`env.DEF` are class ids and the posture/wall flags pick the matchup. - Copy `vibe/duel-posture.mjs` for a new one. `vibeCapture` (`vibe/_lib.mjs`) drives the camera, freezes, and `snapCheck`s every frame — never call `snapCheck` yourself inside a vibe. - `vibe/measure-duel.mjs` is the JS twin of the Rust test — reach for it when you need numbers off the same timeline rather than pixels. ## Run 1. **Rebuild wasm first** — `bun run build:wasm` from `web/`. The harness loads the *prebuilt* wasm, never live Rust; skip this after a `crates/` change and you film a stale binary. 2. Sweep every scenario with `node vibe/all.mjs` from `web/`; one scenario with `node vibe/<script>.mjs`. 3. Frames land at `web/shots/vibe/<scenario>/t###s.png`. ## Read EVERY frame, in order Open `t000s.png` onward and describe what each shows before drawing any conclusion. Do NOT sample two or three and infer the story between them — the in-between frames routinely tell a different story than the endpoints. If a unit "wins," trace *how* across the frames; never assume it from the final count. > A "surrounded square sallies out" test: reading only t48 + t72 showed the > block moving forward and the front enemy dying → "it breaks out of the > encirclement." Reading every frame showed the square ran off after the *front* > unit at t12 and the other two attackers never made contact — no encirclement, > the scenario was broken. Two frames plus a plausible narrative is a confident > wrong conclusion. ## ALWAYS ship a GIF Reading frames one by one is how you *diagnose*; a looping GIF is how the user *watches* the whole sequence at a glance. Whenever the artifact is a time series, surface a GIF (~200 ms/frame, 5 fps) to the user (`SendUserFile`) — never hand back a stack of `t###s.png` with no GIF. - **Vibes do this for free.** `vibeCapture` writes `web/shots/vibe/<name>/timeline.gif` every run, downscaled to 640×400 from the same screenshots the per-frame PNGs gate on. The PNGs stay the full-res regression baselines; the GIF is review-only, committed alongside them (like `shots/models/<owner>/anim/`). Just point the user at it. - **Any other series** (an ad-hoc Playwright sweep, a folder of frames you shot yourself): `node vibe/gif.mjs <dir> [out] [delayMs=200] [downscale=2]`. It orders frames by filename and writes `<dir>/timeline.gif`. Name frames so they sort. - The encoder is `shots/_gif.mjs` (`encodeGif` / `downscaleRGBA`, dependency-free — no ffmpeg/imagemagick on this box). Call it directly for a bespoke series. ## Re-bless A mechanics change turns frames red — that's the point. Once the new behavior is confirmed, re-bless with `UPDATE_SHOTS=1` and commit the baselines as the record. - A full re-bless clears the scenario's baseline folder before writing, so a shorter regenerated timeline cannot leave stale old frames behind. - A timeline re-bless **refuses** `UPDATE_SHOTS=1 SNAP=...`: a filtered regen would clear the folder and then skip frames, leaving gaps. Unset `SNAP` and re-bless the whole timeline. Pairs with [screenshot-regression](../screenshot-regression/SKILL.md) (the snap mechanics every frame obeys), [write-scene](../write-scene/SKILL.md) (the single-state sibling), [write-model-sheet](../write-model-sheet/SKILL.md) (static model review) and [write-anim](../write-anim/SKILL.md) (model-motion review) under `vibe/`, and [tweak-mechanics](../tweak-mechanics/SKILL.md) (the physics work a vibe is the verdict for).