# Seam Craft

Makes scene-to-scene transitions composite cleanly, fixing white flashes at cuts.

- Repository: https://github.com/heygen-com/hyperframes (77062 stars)
- Category: Media
- License: Apache-2.0
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add heygen-com/hyperframes --skill seam-craft -g -a claude-code -y`
Codex: `npx skills add heygen-com/hyperframes --skill seam-craft -g -a codex -y`
Cursor: `npx skills add heygen-com/hyperframes --skill seam-craft -g -a cursor -y`
Gemini CLI: `npx skills add heygen-com/hyperframes --skill seam-craft -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add heygen-com/hyperframes`

## Description

Render-correctness doctrine for scene-to-scene seams in HyperFrames launch videos, the prerequisites that make transitions composite correctly on the master timeline. Load when assembling the master timeline / index.html, when a white flash appears at a cut or crossfade seam (especially on dark films), when reasoning about why a transition opacity dip shows through, or when verifying the render-side mechanics of how overlapping scene wrappers blend. Covers the opaque stage-ground (#root background) white-flash guard and how the injector overlaps wrappers, holds final frames, ping-pongs tracks, and stamps lint-clean template code onto the master timeline. Does NOT contain the per-transition catalog, see the transition registry for individual transition entries.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Seam Craft, render prerequisites for scene-to-scene transitions

This is the **render-correctness doctrine** for PLV scene-to-scene seams: the
prerequisites and master-timeline mechanics that make any transition composite
correctly, independent of which specific transition is chosen. The per-transition
catalog (crossfade, push-slide, zoom-through, cut-the-curve, …) lives in the
transition registry, this page is the doctrine that sits underneath all of them.

The transitions this doctrine governs are **Tier-B-ready**: pure transform / opacity /
filter on the two scene **clip wrappers** (`#el-<sid>`), no injected overlay DOM, no
per-scene cooperation. Overlay families (staggered blocks, blinds, light leak, grid
dissolve, page burn) and shader transitions are deferred to later phases.

## Stage ground prerequisite (white-flash guard)

Several templates open a window where the two wrappers' summed opacity < 1 (the
cut-the-curve mid-window cut, zoom-through's 0.15 floor, plain crossfade's
power-curve dip). Whatever is BEHIND the wrappers shows through during that
window. If the assembled `index.html` `#root` has no opaque background, the
renderer composites the dip over its default **white** page → a white flash at
every seam, glaring on dark films (observed on two Spotify runs before the fix).
**The assembler must paint the stage:** `#root { background:
var(--canvas-deep, var(--canvas, #000)) }`, `assemble-index.mjs` now emits this;
any other consumer of these templates owns the same guarantee.

## How the injector applies a transition

At a `break` boundary between scene _i_ (`from`) and scene _i+1_ (`to`), the
injector:

The rest: https://github.com/heygen-com/hyperframes/blob/HEAD/.agents/skills/seam-craft/SKILL.md