castkit is an agent-native CLI that turns a strict, evidence-backed script into a polished terminal demo video.
handoff init/list/get -> agent DemoScript JSON -> validate -> execute
discover -> validate -> execute -> capture transcript -> screenstudio render manifest -> playwright render -> ffmpeg mux
- ScreenStudio-like polished terminal frame
- smooth activity-following camera zoom
- typed command playback
- output streaming feel
- optional typing clicks and optional background music
- strict JSON schema (
deny_unknown_fields) - every executable step must include valid
source_refs - unsupported command invention fails validation unless explicit
manual_step - non-interactive deterministic execution path
- Rust + ffmpeg
- Node + Playwright Chromium runtime in
renderer-runtime/
Setup:
npm install --prefix renderer-runtime
npx --prefix renderer-runtime playwright install chromium- ScreenStudio renderer is the only execute path.
- Legacy renderer has been removed from CLI flow.
- Verified fixture output exists at
/tmp/deewiki_demo_v4.mp4.