Cadence

A prompt-native, mass-market, enterprise-scale video editor. You describe what you want in plain language; an AI Director edits the video and shows the result — always editable. The project is stored as edits-as-code: a declarative EditDoc that any renderer can turn into pixels.

See AGENTS.md for the full build brief and rules, and ARCHITECTURE.md for how it fits together.

• Node 20+ (Node 22 LTS recommended; this repo is pinned/tested there).
• Optional, free, only for later slices: Docker (docker compose up) and ffmpeg (video export).

npm install
npm run typecheck   # tsc across all packages
npm run verify      # renders one real frame headlessly and asserts success

npm run verify writes a proof frame to .cadence/verify-frame.png.

Run the editor:

npm run dev --workspace @cadence/web   # http://localhost:3000  (open /editor)

Real .mp4 export + Postgres persistence: docker compose up (ffmpeg baked in). Deploy to Vercel: see DEPLOY.md.

packages/core          engine-agnostic EditDoc schema (source of truth) + RenderEngine contract + pure helpers
packages/render-node   headless canvas RenderEngine (no browser/ffmpeg/Docker needed)
packages/render-ffmpeg pure EditDoc -> ffmpeg filtergraph plan + runExport (real .mp4)
packages/director      Director tools + pure edit ops (highlight, tracks, trims, keyframes, transitions, demo, transcript, ...)
packages/understanding transcripts (Whisper CLI or offline stub) + pluggable TTS seam
packages/enhance       pluggable faithful upscale providers (free / local / api / cli)
packages/db            multi-tenant Postgres (migrations, pooled client, tenant-scoped repos)
apps/web               Next.js editor + API (the app)
scripts/verify.ts      the render-verify gate ; scripts/evals.ts  capability evals

1. Edits-as-code — the EditDoc is the single source of truth.
2. Never code library APIs from memory — verify from .d.ts/docs first.
3. Agentic loop — plan → smallest slice → typecheck + verify → fix → commit.
4. Render-verify gate — if it doesn't render one frame, it isn't done.
5. Scale by construction — client preview, splittable render, engine-agnostic ops.
6. Money gate — never enable a paid/metered service without asking; free fallback first.

A prompt-native + full manual editor (CapCut-style), all edits-as-code so preview, canvas, and export stay in sync:

• AI: describe an edit in chat; highlight cuts, reframe, captions from speech, edit-by-transcript, silence removal, auto-reframe, looks, slideshows, and an interaction/walkthrough builder from screenshots.
• Manual timeline: multi-track layers with track headers (hide/show, lock, mute/solo, rename, reorder, add/remove), drag clips between tracks, trim/split/ ripple, roll/slip/slide, an on-timeline keyframe editor, per-cut transitions, audio fade handles, beat-sync, stickers/emoji + text presets, and a playhead-anchored zoom.
• Rooms: Media · Edit · Words · Color · VFX · Audio · Deliver · Demo.

Full feature list: FEATURES.md. CapCut parity status: docs/CAPCUT-STATUS.md.

Social MVP + the manual/AI editor (CapCut-parity waves A–E) are built and verified; Neon Postgres is wired and Vercel deploy is ready. See TASKS.md and CHANGELOG.md for the slice-by-slice history. The stub Director (free) is the default; the real Claude Director (Anthropic API, metered) is behind a money gate and off by default — as are AI upscale and TTS.

• Emoji artwork: Twemoji (c) Twitter, Inc and other contributors, licensed CC-BY 4.0; vendored in apps/web/public/emoji (see ATTRIBUTION.md there). Emoji names/keywords: emojibase-data (MIT).
• Fonts: see apps/web/public/fonts/LICENSES.md.