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.
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.
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).
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.
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
Reproducibility	Time-driven only, seeded PRNG, double rAF, proven vs reported flags; CSS 3D and lit WebGL paths	determinism.md
Stages	stills (default, one per beat) → draft → master, budget log, `--jobs` chunks	stages-budgets.md
Encoding	libx264 yuv420p BT.709 faststart; GIF palettegen/paletteuse; master motion blur from subframes + `tmix`	encoding.md
Delivery	GIF inline + mp4 link on GitHub	delivery-github.md
Terminal	VHS tape + scripted demo	vhs-terminal.md
Proof	ffprobe facts, exact frames, budgets, SSIM, spikes, color tags	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

Critical Rules

seek(t) is pure — same t, same pixels, any order. No CSS animation, no wall clock, no unseeded randomness, no state between frames.
--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.
Verify the file, not the frames — exact DURATION x FPS frames, h264/yuv420p, budget, SSIM vs approved stills. "ffmpeg exited 0" is not proof.
No invented flags or APIs — every Chrome/ffmpeg option is either proven by the reference pipeline or labelled "reported, verify".
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).
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 for the complete CLI

Reference Guide

Concepts

Topic	Reference	When to Consult
Seek contract	seek-contract.md	Writing/porting a scene; GSAP/WAAPI adapters; canvas camera
Determinism	determinism.md	Drift, stutter, blank frames, cuts on frame boundaries
Stages & budgets	stages-budgets.md	Choosing a stage, long films, render counts
Encoding	encoding.md	mp4/GIF settings, color shift, banding, over budget
GitHub delivery	delivery-github.md	README/docs embedding, size limits
VHS terminal	vhs-terminal.md	Terminal/CLI films
Verification	verification.md	After every master, before "done"
Audio	audio.md	Brief asks for music/SFX

Templates

Template	When to Use
capture-cdp.md	`.motion/capture.js` — zero-dep Chrome capture
render-cli.md	`.motion/render.js` + `encode.js` — stages, encoders, verification
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	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	A lit three.js beat: pinned local three r186, SwiftShader, twice-rendered sha256 proof or CSS 3D fallback
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	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

motion-render

Motion Render

Agent Workflow (MANDATORY)