motion-render · git:20261012.499a4d1 · 2026-10-12 · sha256 1934f0ca495465cc
motion-render git:20261012.499a4d1A
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--- name: motion-render description: "Use when turning a locked brief and beat map into a film file — deterministic seek(t) scene split into classic scripts (springs, springSum, stagger, density validator, actor, CSS 3D, cursor interaction, pinned lit three.js), zero-dependency Chrome capture, staged render (stills one per beat → draft → master with subframe motion blur, stills by default), ffmpeg mp4 + GIF, VHS terminal films, audio on a measured beat grid, and verification of the delivered file." versions: fuse-motion: "1.0.0" ffmpeg: "9.0.2" bun: "1.4.2" vhs: "0.12.1" user-invocable: true references: references/seek-contract.md, references/determinism.md, references/stages-budgets.md, references/encoding.md, references/delivery-github.md, references/vhs-terminal.md, references/verification.md, references/audio.md, references/templates/capture-cdp.md, references/templates/render-cli.md, references/templates/timeline-seek.md, references/templates/interaction-kit.md, references/templates/webgl-scene.md, references/templates/index-skeleton.md, references/templates/vhs-tape.md related-skills: motion-art-direction, motion-method, motion-craft, motion-assets, motion-review, fuse-design:design-motion --- <objective> The production half of the fuse-motion pipeline: from `.motion/brief.md` and `.motion/beats.md` (owned by `motion-method`) to a verified file. A film is a pure function of time — an HTML or canvas scene exposing `window.seek(t)` — captured frame by frame by headless Chrome over the DevTools Protocol with zero dependencies, then encoded by ffmpeg (H.264 mp4 + palette GIF). Rendering is staged: `stills` (the default when `--stage` is omitted, so a forgotten flag can never skip a gate) → owner gate G1 → `draft` 540p → critic + owner gate G2 → `master`, whose FILE is verified by ffprobe, frame count, byte budget and SSIM against the approved stills. Terminal subjects use VHS tapes; sound, when the brief asks for it, follows the audio reference. Templates are generalized from the proven `docs/demo/statusline-mod/` and `docs/demo/hook-sniper.tape` pipelines and were run end to end before shipping. </objective> # Motion Render ## Agent Workflow (MANDATORY) 1. **Read the locked inputs**: `.motion/brief.md` (surfaces, byte budgets, aspect, duration) and `.motion/beats.md` — if either is missing, go back to `motion-method`. 2. **Check tools**: `ffmpeg -version`, `ffprobe -version`, `bun --version`, a Chrome binary (or `CHROME_BIN`); `vhs --version` + `ttyd` for terminal films. Missing tool → say so, never fake a render. 3. **Scaffold the scene**: `motion-art-direction` templates FIRST — composition-grid (layout), kinetic-type (word behaviours), cut-rhythm (beat map) — only after `look.md` and the key frames exist. This skill then adds the mechanics: the shell, the `seek` clock, capture and encode (never hand-roll a capture). 4. **Render `stills`** → STOP at G1. **`draft`** → `motion-critic` → STOP at G2. **`master`** → verify the FILE. The harness `motion` scope denies draft/master until the owner types `MOTION-APPROVE` — stop at each gate anyway, never lean on the deny. 5. **Hand off**: lead runs `fuse-ai-pilot:sniper` on the scripts and the challenger on the "done" claim. --- ## Overview | Concern | Choice | Reference | |---------|--------|-----------| | Scene | DOM, 2D canvas or a WebGL layer with `window.seek(t)`, DURATION, FPS, STILLS, ready; a gesture in progress at every moment (`validateDensity`); look from `motion-art-direction` | [seek-contract.md](references/seek-contract.md) | | Reproducibility | Time-driven only, seeded PRNG, double rAF, proven vs reported flags; CSS 3D and lit WebGL paths | [determinism.md](references/determinism.md) | | Stages | stills (default, one per beat) → draft → master, budget log, `--jobs` chunks | [stages-budgets.md](references/stages-budgets.md) | | Encoding | libx264 yuv420p BT.709 faststart; GIF palettegen/paletteuse; master motion blur from subframes + `tmix` | [encoding.md](references/encoding.md) | | Delivery | GIF inline + mp4 link on GitHub | [delivery-github.md](references/delivery-github.md) | | Terminal | VHS tape + scripted demo | [vhs-terminal.md](references/vhs-terminal.md) | | Proof | ffprobe facts, exact frames, budgets, SSIM, spikes, color tags | [verification.md](references/verification.md) | | Sound | Licensed track ~120 BPM, beat grid measured from the song, start on a downbeat, SFX by measured peak, -14 LUFS, silent cut | [audio.md](references/audio.md) | --- ## Critical Rules 1. **`seek(t)` is pure** — same `t`, same pixels, any order. No CSS animation, no wall clock, no unseeded randomness, no state between frames. 2. **`--stage` defaults to `stills`** — omitting it cannot skip a gate; unknown values exit 2. Pass a literal stage: the harness counts `--stage "$S"` as master. Stop at G1 and G2. 3. **Verify the file, not the frames** — exact `DURATION x FPS` frames, h264/yuv420p, budget, SSIM vs approved stills. "ffmpeg exited 0" is not proof. 4. **No invented flags or APIs** — every Chrome/ffmpeg option is either proven by the reference pipeline or labelled "reported, verify". 5. **Facts from files only** — on-screen numbers from `.motion/facts.md`, labelled example data; no client names, no real spend, real masked screenshots (`motion-assets`). 6. **Fix in the scene, not with re-renders** — a critic finding is a code change + a new draft, never a sequence of masters. --- ## Architecture ``` .motion/ ├── brief.md, beats.md, facts.md, assets.json ← motion-method / motion-assets ├── scene/index.html + lib.js, beats.js|rhythm.js, grid.js, kinetic.js, timeline.js │ ← classic scripts in that order (each within `FUSE_SOLID_MAX_LINES`): │ index-skeleton.md shell + timeline-seek.md clock ├── capture.js ← capture-cdp.md ├── render.js + encode.js ← render-cli.md ├── terminal.tape + terminal-demo.sh ← vhs-tape.md (terminal films) ├── stills/ still-1..N.png, contact.png (G1 artifact) ├── out/ draft.mp4 (G2 artifact), master.mp4, master.gif ├── review/ review pack (motion-review) ├── work/ frames + Chrome profiles (gitignore) └── budget.json renders per stage + wall time ``` → See [render-cli.md](references/templates/render-cli.md) for the complete CLI --- ## Reference Guide ### Concepts | Topic | Reference | When to Consult | |-------|-----------|-----------------| | **Seek contract** | [seek-contract.md](references/seek-contract.md) | Writing/porting a scene; GSAP/WAAPI adapters; canvas camera | | **Determinism** | [determinism.md](references/determinism.md) | Drift, stutter, blank frames, cuts on frame boundaries | | **Stages & budgets** | [stages-budgets.md](references/stages-budgets.md) | Choosing a stage, long films, render counts | | **Encoding** | [encoding.md](references/encoding.md) | mp4/GIF settings, color shift, banding, over budget | | **GitHub delivery** | [delivery-github.md](references/delivery-github.md) | README/docs embedding, size limits | | **VHS terminal** | [vhs-terminal.md](references/vhs-terminal.md) | Terminal/CLI films | | **Verification** | [verification.md](references/verification.md) | After every master, before "done" | | **Audio** | [audio.md](references/audio.md) | Brief asks for music/SFX | ### Templates | Template | When to Use | |----------|-------------| | [capture-cdp.md](references/templates/capture-cdp.md) | `.motion/capture.js` — zero-dep Chrome capture | | [render-cli.md](references/templates/render-cli.md) | `.motion/render.js` + `encode.js` — stages, encoders, verification | | [timeline-seek.md](references/templates/timeline-seek.md) | The scene split into classic scripts (`lib.js` → `beats.js` → blocks → `timeline.js`): springs ζ ≥ 0.85, `springSum`, `stagger`, `validateDensity` (0.75 s / 1.2 s / 1 per s), the recurring actor, a flat CSS 3D cube; or the dense 2D-canvas scene | | [interaction-kit.md](references/templates/interaction-kit.md) | One continuous object driven by a cursor: dual-edge springs, click/drag with spring-back, `swapBlur` (≤ 0.1 s, ≤ 8 px), loop seam check | | [webgl-scene.md](references/templates/webgl-scene.md) | A lit three.js beat: pinned local three r186, SwiftShader, twice-rendered sha256 proof or CSS 3D fallback | | [index-skeleton.md](references/templates/index-skeleton.md) | `.motion/scene/index.html` mechanics — stage = VIEW, kill-switch, local fonts, hidden shots, actor, rule, CSS 3D cube, script order | | [vhs-tape.md](references/templates/vhs-tape.md) | Terminal film: tape + scripted demo | --- ## Best Practices ### DO - Render stills twice when touching the scene's clock: the contact sha256 must not change - Put hard cuts on frame boundaries (`t = k / FPS`) so a cut lands on the same frame at every rate and in every chunk - Use `--jobs` past ~25 s; frames keep a global index - Run the `motion-review` pack (spikes, phone view) on the draft and the master - Report renders per stage, wall time, sizes vs budgets, SSIM and spikes ### DON'T - Capture the preview loop or record the screen in real time - Add motion blur to stills or the draft — master only, `--subframes` (4 default, ≥ 12 if any move > ~2 % W/frame — encoding.md), cuts on frame boundaries - Ship a lit WebGL beat without the twice-rendered sha256 proof, or load three from a CDN at render time - Build a crossfade or dissolve, or an opacity-only entrance — banned (`motion-craft` anti-slop-video.md) - Write a scene file over the hook ceiling `FUSE_SOLID_MAX_LINES` — split it into another classic script - Leave frame 0 blank or fading in — `seek(0)` shows the opening statement at full value - Add a "reported" Chrome flag without the twice-rendered hash test - Lower the SSIM threshold to make a master pass — investigate the change - Commit `.motion/work/` frames or Chrome profiles - Use Remotion as a dependency (license — mention it only as an alternative) - Copy design-motion's UI micro-durations into film holds — films use `motion-craft` holds