# FAQ

Short answers to common questions and failures, with links to the pages that say more.

## Does anything leave the machine?

Scenes, frames, renders, and sounds stay in the project folder. Agent sessions talk to Claude, as Claude Code does. GitHub is contacted only to install a style that isn't local.

## Do I need Claude Code to render?

No. `rapid render`, `still`, `sheet`, `check`, `join`, `mix`, `mux`, `phone`, and the style and format commands run without the daemon or an agent. `rapid video --review none` on a project whose storyboard and scenes exist runs no agent. Agents write storyboards, build scenes, and review them.

## The CLI says no daemon is running.

``rapid: No rapid daemon is running at http://127.0.0.1:4317. Start one with `rapid serve`.`` Run `rapid daemon ensure` (background) or `rapid serve` (foreground), or press **Start daemon** in the pane. `rapid video`, `rapid open`, and the MCP tools start one themselves. On another port, set `RAPID_PORT` or `RAPID_URL`.

## A scene rendered nothing.

Any problem fails the whole render: an uncaught error, a throwing frame callback, an asset or font that didn't load. `rapid render` names the first and its time. See [when a render fails](/docs/writing-scenes#when-a-render-fails).

## The same frame differs between renders.

Something draws from state instead of time: a counter bumped per frame, a timer chain, motion started after load. Chunks seek out of order; compute from `t` in `rapid.frame`, or use GSAP timelines, CSS, or Web Animations made at load. See [determinism](/docs/scenes#determinism).

## Can a scene load a font or library from the web?

No. A scene reaches nothing outside its folder (a project's scene: the project). Put the font beside it, use an installed face, or use a style that ships its faces (`poster`). Libraries are the pinned ones: `rapid:lib/gsap@3.15.0` and [rapid's own](/docs/shots), each `@1`.

## An element moving off the edge is marked.

It shouldn't be: placement checks hold only elements at rest, and an element wholly off the frame isn't seen. If it is marked, it is at rest past the edge; hide it once it has gone.

## A check marks my background as outside the safe area.

Give full-frame fields `data-role="texture"`; textures aren't held to the safe area or keep-outs.

## A check says nothing moves.

The `dead` check marks any span over 0.8 s where nothing on screen moves. Add secondary motion (`rapid:lib/motion@1`), or list the span in the meta's `holds` when the stillness is the point.

## How do I change one scene without re-rendering the video?

Edit `scenes/<id>.html`, then `rapid redo <render node>`. Only what depends on it runs again: its checks, sheet, review, then the join, mix, mux, and phone copy. See [fingerprints](/docs/the-job-graph#fingerprints-and-staleness). With a finished video, `rapid revise <job> --scene <id> --note "…"` does the build for you.

## How do I tell a builder what to change?

`rapid redo <build node> --note "…"`, Redo with a note in the pane or the screening page, or `rapid revise`. Every note on a node goes into the agent's prompt.

## How do I make it cheaper, or the machine less busy?

Lower `slots` in `$RAPID_HOME/config.json`: `think` for agents, `web` for Chrome. See [lanes](/docs/lanes). `--keys off` and `--director none` drop the key-frame and direction passes.

## Where are installed styles?

`$RAPID_HOME/styles/<name>/<version>/` (`~/.rapid` by default), read-only. A project pins what it uses in `rapid.lock`.

## Do I need Blender or uv?

Only for the feature each serves: `uv` for a video [cut to a track](/docs/music), Blender for [product shots](/docs/blender-shots). Everything else runs without them.

## A font fails the check.

A style names its faces and allowed substitutes. A face you lack, with no allowed substitute present, fails by name. Install the face, or use a style whose faces you have.

## Is there a length limit?

No. The built-in formats have no maximum; the phone copy drops to 720p after 120 s to stay under its cap.

## Is the machine ready?

`rapid setup --check`, or `/rapid setup` in Claude Code. See [install](/docs/install#3-rapid-setup---check).

## An agent can't sign in.

Agents use Claude Code's sign-in. Run `claude`, then `/login`, or set `ANTHROPIC_API_KEY` for the daemon.

## A command failed with one line.

Every failure prints one line, `rapid: <what went wrong>`, and exits 1. `RAPID_DEBUG=1` prints the whole error.

## My scene looks the same in every style.

It sets its own colours, faces, or sizes. Link `rapid:style`, use [the kit](/docs/styles-and-formats#the-kit) and the `--rapid-*` properties, and keep your own CSS to layout.