cap - SKILL.md Agent Skill

name: cap description: >- Record the screen, capture screenshots, and create shareable video links from the command line using the Cap CLI. Use when the user wants to record a screen demo or bug repro, capture a screenshot of a screen/window, produce a Loom-style shareable video link, or automate/script screen recording. Requires the `cap` command to be installed (Cap Desktop, https://cap.so).

Cap CLI

cap is a command-line screen recorder built to be driven by agents. Every command takes --json for machine-readable output on stdout; stderr stays human-readable; failures exit non-zero and, in --json mode, print a final object/event with an error field.

cap guide --json is the authoritative contract (output convention, env vars, exit codes, and every command's output mode + event tags). Prefer it over guessing, and cap <command> --help for flags.

First: check it's available

cap doctor --json

If cap is not found, it isn't installed. Tell the user to install Cap Desktop from https://cap.so/download, then enable the CLI (Settings → Command Line), or run curl -fsSL https://cap.so/install-cli.sh | sh (Windows: irm https://cap.so/install-cli.ps1 | iex).
Read captureReady and permissions.screenRecording from the output. On macOS, recording fails until Screen Recording permission is granted in System Settings.

Discover capture targets

cap targets --json     # screens, windows, cameras, mics

Use a screen's id (or a window's id) for --screen/--window, a camera's deviceId for --camera, and a mic's name for --mic.

Record (background lifecycle — the usual agent pattern)

When you don't know the duration in advance: start detached, do the work, then stop.

cap record start --screen <id> --json --detach   # -> {"type":"started","recordingId","pid","path"}
# ... perform the actions to capture ...
cap record stop --id <recordingId> --json        # -> {"type":"stopped","path","recordingMetaExists":true}
cap record status --json                          # list active sessions

A stopped event is only a complete recording when recordingMetaExists is true.

Fixed-length alternative (no detach): cap record start --screen <id> --duration 10 --json.

Screenshot

cap screenshot --screen <id> --path shot.png --json   # -> {"path","width","height"}

Export and share

cap project validate <path.cap> --json        # confirm the recording is complete
cap export <path.cap> --output out.mp4 --json # render (here --format means container: mp4|gif|mov)
cap upload out.mp4 --json                      # -> {"type":"uploaded","id","link"}

cap upload authenticates automatically by reusing the user's Cap Desktop login — check with cap auth status --json. If it reports authenticated:false, tell the user to sign into Cap Desktop, or set CAP_API_KEY (a Cap auth key from Settings) for headless use. cap upload <path.cap> --export --json exports then uploads in one step.

Conventions to rely on

Add --json to any command; it overrides each command's --format.
Detect failure with a single check: the process exits non-zero and the JSON carries an error field.
record and export stream newline-delimited JSON (NDJSON) events; everything else returns one object.
doctor, project validate, and recordings list are reports — branch on their fields (ok/captureReady, valid), not just the exit code.