cadence

name: cadence description: Create a changelog, launch, announcement, or milestone video for ANY repo / package / release using the cadence CLI. Use whenever someone wants a video, reel, teaser, or animated showcase for a software feature, release, PR, changeset, SDK/CLI update, or milestone — phrasings like "make a changelog video for ", "announcement video for the v2 release", "showcase the new ", "a reel for our latest npm release", "render a 9:16 of 's changelog", "milestone video — 1M downloads". Point it at a local repo path or a GitHub repo. It reads the project, writes a small data file, and renders an MP4. Trigger even when the user doesn't say "Remotion", "beats", or "render".

cadence

Turn a software update into a rendered video. A video is a list of "beats" (a small JSON data file); the cadence engine owns motion, fonts, layout, the typewriter, code highlighting, and the backdrops. Your job: read the target repo, figure out what changed, write honest beats, and render.

This works for any project — a TS SDK, a Rust/Go CLI, a library — not a specific product.

The engine

Everything runs through one CLI. Install it once for a persistent cadence binary (npm i -g @waits/cadence), or invoke it without installing as npx @waits/cadence … — either way it renders locally on the user's machine (free, no hosted service, no key needed for a render). The examples below write cadence … as shorthand for either form. If the project already depends on the engine you can use bun run cli … instead.

cadence create <repo|beats.json>    # the build verb (repo → video, or a beats file → video)
cadence storyboard <beats.json>     # preview: plan + one still per beat → a sheet (no MP4)
cadence create … --dry-run          # same preview, straight from a repo (no MP4)
cadence audit <beats.json>          # heuristic checks on a beats file (ranked, no auto-fix)
cadence study --from-url <url>      # a brand URL/color → a theme JSON
cadence themes                      # list built-in themes

Workflow

1. Identify the target. A local path or a GitHub repo (owner/name). You don't need the engine's source — you drive it through the CLI.
2. Find the latest release / what changed (the input). Prefer, in order:
   • gh release view --repo <owner/name> / gh release list (release notes), or
   • git tag --sort=-creatordate + git log <prev>..<latest> (commits), or
   • a CHANGELOG.md — but verify it's current; many repos leave it stale (e.g. changesets with changelog:false), so cross-check against tags. Pick the 1–4 most demo-worthy changes; each becomes a beat.
3. Write honest code (the moat). Never invent API. Climb the honesty ladder and stop at the first rung that gives real symbols:
   1. Types — the package's .d.ts / exported types (truest source).
   2. Examples — examples/, tests, doc snippets.
   3. README — documented usage / CLI commands / install line.
   4. Install-only — if you can't verify a call, fall back to just the install command + prose; do not show a fabricated snippet. Capture the real install (npm i …, brew install …, cargo add …) and the real class/command names exactly (casing matters — e.g. SecondLayer, not Secondlayer).
4. Write <slug>.beats.json — a ChangelogInput as JSON (see references/authoring.md for every field). Everything is JSON-serializable; don't author tokens (shiki fills them) or usually motion (defaults are right). Omit background entirely to get the default procedural, theme-colored backdrop.
5. Storyboard — preview the whole arc before the MP4. Run cadence storyboard <slug>.beats.json (or cadence create … --dry-run straight from a repo): it prints the beat-by-beat plan + pacing notes and renders a contact sheet (out/<slug>.storyboard.png), one still per beat, no MP4. Show it to the user and iterate — re-skin with cadence redesign … --theme/--background, fix content by editing the beats — re-running storyboard until the arc + look are right. This is the design loop; don't jump to a full render.
6. Render. Once the storyboard looks right, render the MP4 (and social formats if asked) with the locked --theme/--format. (cadence create <slug>.beats.json --frame 150 still gives a fast single-frame check of one moment.)

Authoring in TypeScript (with types) also works when you're inside the engine repo: a <slug>.beats.ts that export defaults a ChangelogInput. JSON is the portable form and is what to use everywhere else.

Interpreting the request (natural language → beats)

• announcement / launch / teaser → install opener ($ npm i … + feature pills) → 1-3 code+panel feature beats → hero closer (package + tagline). This is the feature-launch default; pass flow:"title-open" for the classic title-open/install-close instead.
• changelog / what's new / new in X → feature beats; eyebrow "new in <project> <version>".
• milestone / N downloads / now stable → a stat beat centerpiece.
• showcase / highlight → feature beats with the panel that shows the result.
• format: "vertical/reel/shorts" → 9x16; "square/feed" → 1x1; else 16x9.

Keep it tight: 3-6 beats. Pick what's visual.

Beat shapes

• Install opener — layout:"center" + a bash install code block + badge (e.g. "v1.7") + caption (terse feature pills, "sync · folders · read-only"). The default open for a launch reel (the feature-launch template emits this).
• Opener (title) — headline + eyebrow only (classic title card).
• Feature — headline + code + panel (code left, render/result right at 16:9). Default to pairing code with a panel — show the result, not just a title.
• Stat / milestone — a stat panel (one big number).
• Hero closer — hero: true + layout:"center" + headline (package name) + caption (one-line pitch). A big centered title to close on (package + tagline).
• Install / CTA closer — layout:"center" + a bash/install code block + badge + caption (when you'd rather end on the install).

Panel picker (panel.kind) — choose by what the change produces

Exact fields per kind: references/authoring.md.

Rules that matter

• Honest code only (the ladder above) — it's the product's whole credibility.
• Sequencing is automatic — the engine types the code, then runs the panel. Just give code + panel.
• Headlines short + declarative ("Lint as you check.", "The mempool, indexed."). Eyebrow lowercase ("new in clarinet 3.18"), renders as a gold uppercase label.
• One background per video for continuity (or omit it on every beat for the consistent procedural default).

Brand it (theme)

A video reads its colors, fonts, and code styling from a theme. To match a brand:

• Capture the project's brand in <project>/.cadence/theme.json (a ThemeConfig). cadence auto-discovers it when run against that project (it walks up from the beats file), so no --theme-file is needed — and no brand-specific files land in the engine. Scaffold with cadence study --accent "#10b981" --out <project>/.cadence/theme.json (or --from-url <url>), then hand-tune. This is the preferred way to brand a video.
• Match the project's docs code snippets. The theme styles the code window too — set fonts.mono, the codeTheme syntax colors + codeBg to the project's docs highlighter, and codeChrome: "minimal" for a chromeless, docs-style window (default "window" is the floating editor with traffic-light dots). Verify with cadence storyboard <beats> and compare to the real docs so on-screen code matches.
• From a screenshot / URL: read the palette yourself and write the ThemeConfig — the dominant brand color becomes signalBlue; copy a built-in as a template (cadence themes lists them).
• Or a built-in named theme: cadence create <beats> --theme <name>. Precedence: --theme-file > --theme > the project's .cadence/theme.json > default.

Custom painted backgrounds (optional, needs OPENAI_API_KEY): cadence art --prompt "<scene>" --name <slug> generates a backdrop into <project>/.cadence/backgrounds/_candidates/; cadence art --promote <slug> moves the keeper to .cadence/backgrounds/; then reference it in a beat as background: { src: "backgrounds/<file>.png" } (cadence stages it at render). Reusable subject sets: --pack <file.json>; --brand tints art toward the project's theme palette. The bundled default pack is the Austin "Hill Country Sublime" landmarks — reuse one without any key/generation by referencing it directly (background: { src: "backgrounds/pennybacker.png" }; also capitol, congress, mount-bonnell, enchanted-rock, hamilton-pool, barton-springs, ut-tower), or regenerate a branded variant with cadence art --landmark <camelKey> --brand (keys: pennybacker, utTower, capitol, congress, mountBonnell, enchantedRock, hamiltonPool, bartonSprings). Default backdrop stays procedural — only reach for this when the user wants painted art. See docs/guides/custom-backgrounds.md.

Render

cadence storyboard <slug>.beats.json             # preview: plan + one still per beat (no MP4)
cadence create <slug>.beats.json                 # 16:9 mp4 → out/
cadence create <slug>.beats.json --format 9x16   # vertical
cadence create <slug>.beats.json --frame 150     # one still (fast preview)
cadence create <slug>.beats.json --theme slate   # a built-in theme

Storyboard takes --theme/--theme-file/--format (not --frame).

Outputs land in <project>/.cadence/out when run against a repo that has a .cadence/ dir (anchored to the project, not the cwd), else ./out. Override with --out <dir>.

Reference

• references/authoring.md — full vocabulary: beat fields, panel kinds, motion, formats, backgrounds, sequencing, typography.
• Worked example beats files ship inside the engine package (under its src/content/) if you want to see complete videos.