Video toolchain

A prerequisite gate for every kit skill that renders video frames locally. Run it before scaffolding a project or telling the user a video can be made: a render that dies at frame 300 because ffmpeg or Chrome is missing wastes the whole run.

uv run --no-project .agents/skills/video-toolchain/scripts/video_toolchain.py
uv run --no-project .agents/skills/video-toolchain/scripts/video_toolchain.py --json   # machine-readable
# overrides: --python <binary>   --chrome <path>

Exit 0 = every required tool present. Exit 1 = at least one required tool missing; each missing tool prints a fix: line with its remediation (install command or env var to set). The check is read-only and stdlib-only: it only probes tools already on the machine (the uv candidate for numpy + Pillow may provision its package cache on first use; no project file is touched).

What it probes

Tool	Probe	Required by
node	node --version	kinetic-reel, painted-animation (npm install, render.mjs)
ffmpeg	ffmpeg -version	every render skill (frame encoding)
python + numpy + Pillow	import numpy, PIL via --python, the uv env (uv run --no-project --with numpy --with pillow), python, python3	lemo-opuscar styles (paper.py texture helpers)
chrome	--chrome > CHROME_PATH > PLAYWRIGHT_CHROME > standard install paths > PATH	headless Chrome rendering (render.mjs)
ruby	ruby --version	optional - motion-graphics-music-video only; never fails the run

Notes:

• Output size discipline (from the live 2026-10-19 rehearsal): the default kinetic-reel encode produces roughly 100 MB for a 17 s film - after each successful render, also produce a web copy (ffmpeg -vf scale=1600:900 -crf 23 -preset slow -movflags +faststart) before delivering.
• Paid or keyed upstreams stay opt-in: anything needing an API key (for example the FAL_AI_API_KEY env var referenced by motion-graphics-music-video) is never vendored or run by this check; the key name alone may appear in docs.
• The Chrome probe never writes anything and never launches a browser session; it only verifies the executable exists. The render skills launch it headless.
• Onboarding audit, per-repo decisions and the lemo-opuscar pointer workflow: docs/video-skills-2026-10-19.md in the agents-kit repository.

Exit contract for the calling skill

1. video_toolchain.py exit 1 -> stop, report the missing tools and their fix: lines to the user, do not attempt the render.
2. Exit 0 -> proceed; re-check only when a tool invocation later fails with "not found" (PATH may differ in nested shells).