motion-doctrine

An agent skill by heygen-com, from heygen-com/hyperframes. Tags: debugging, design, motion-graphics, video.

What it does

GATEWAY — load FIRST before composing any HyperFrames animation or video. The high-level motion law that makes a multi-scene video feel like ONE continuous camera move instead of a stack of independently-animated slides. Covers the vector law (how you exit determines how you enter, incl. the Z scale-sign rule), the film's current, carrier elements, causal motion, the Seam Gate (build-gate enforcement), the ban on idle wobble (motion must PERFORM, not breathe), stillness-before-climax, and the sustained-motion routes. Routes to the low-level technique skills (cut-the-curve — the full catalog incl. waterfall entry + nudge curve, oversized-cursor, seam-craft). These rules SUPERSEDE generic / upstream motion guidance. [continuity, direction, vector, momentum, seam, transition, ease, performance, idle-motion, narrative-motion, film-grammar]

Install

With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:

npx skills add heygen-com/hyperframes --skill motion-doctrine

Or copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):

git clone --depth 1 https://github.com/heygen-com/hyperframes
cp -r hyperframes/.agents/skills/motion-doctrine ~/.claude/skills/motion-doctrine

Safety box score

Grade C, moderate risk: 32 of 100 risk points, rated 2026-10-18. The grade rates what the skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. How the score works.

This skill is a local HyperFrames motion-seam tool: it rewrites `index.html` from a ledger and launches a browser-based verifier. The main risks are shell execution in the verifier, optional `npx` fallback to fetch and run a preview package, and in-place mutation of project HTML.

Category levels, from 0 (none) to 3 (high)
Category	Level	Why
Code & shell execution	3 (high)	`scripts/seam-gate.mjs` spawns a shell with `spawn("sh", ["-c", cmd...])` and can run `npx --yes hyperframes preview`, so it can execute arbitrary commands and fetched code.
Network access	2 (moderate)	The verifier does HTTP polling (`fetch(base + "/api/projects")`) and opens a WebSocket to Chrome (`new WebSocket(url)`), and its fallback path can contact the npm registry via `npx`.
Filesystem reach	2 (moderate)	`scripts/seam-stamp.mjs` rewrites the target HTML in place with `writeFileSync(target, html)`, and `seam-gate.mjs` also reads from `~/.cache/puppeteer` and the project tree.
Secrets & credentials	0 (none)	No file reads or code paths target tokens, cookies, keychains, `.env` files, or browser session stores; the Chrome session is only used for page inspection.
Privilege & persistence	0 (none)	There is no sudo, service registration, global install, shell-startup editing, or OS-setting change in the shipped files.
Instruction hijack surface	0 (none)	The skill is directive, but it does not contain hidden prompt text or instructions to ignore higher-priority rules, skip confirmations, or conceal actions.
Irreversible actions	1 (low)	It automates project changes and verification (`--write index.html`, `verify`, `probe`), but it does not deploy, publish, message, pay, or delete external resources.
Transparency	1 (low)	The repo is readable, but runtime behavior can depend on opaque local/external binaries (`~/.cache/puppeteer`, system Chrome, and optional `npx`-fetched `hyperframes`).

Before installing

Read `scripts/seam-gate.mjs` first and decide whether `sh -c` plus the `npx` fallback is acceptable for your machine.
Test `scripts/seam-stamp.mjs --write` on a disposable copy of `index.html`; it overwrites the target file in place.
Only use `seam-gate.mjs --url` against a local preview you control, not a sensitive or remote site.
Confirm the required Chrome path/cache (`~/.cache/puppeteer` or system Chrome) is acceptable on your account.

Rated 2026-10-18 by an automated review of 4 files from the skill's repository.

Source

Repository: heygen-com/hyperframes (all skills from this repository)
Path: .agents/skills/motion-doctrine/SKILL.md
Branch: main
Updated: 2026-09-19

cut-the-curve — The technique catalog: five velocity-matched SEAMS (zoom-through, INVERSE zoom-through, cut-the-curve, waterfall cut.
seam-craft — Render-correctness doctrine for scene-to-scene seams in HyperFrames launch videos — the prerequisites that make transitions composite correctly on the master.
ad-creative — When the user wants to generate, iterate, or scale ad creative — headlines, descriptions, primary text.
captions-overlay — Overlay doctrine for the embedded-captions workflow — the caption MODEL (drop / rail / embed) and the rule that captions are an OVERLAY composited on top of.
embedded-captions — Add captions or subtitles to an existing single-subject talking-head video without editing the footage.
faceless-explainer — Turn arbitrary text — an article, notes, a topic, a brief — into a faceless explainer video: there is no site or footage to capture.