| name | argent-screen-recording |
| description | Record a video of an iOS simulator or Android emulator/device screen using argent MCP tools. Use when the user asks to record the screen, capture a video of a flow, interaction, or animation, produce a screen recording, or document app behavior as a video clip. |
1. Tools
screen-recording-start — start capturing the screen of a booted device to a video file. Frames come from the same simulator-server backend that screenshot and the interaction tools already use, and are encoded live to h264 mp4 (constant 30 fps, device-native resolution).screen-recording-stop — stop the capture, finalize the container, and retrieve the video as a downloadable artifact (video.hostPath for co-located clients).
One recording per device at a time; different devices can record concurrently. Recording does not disturb anything else reading the device — a preview window can stay open on the same screen.
2. Critical: never leave a recording running
A recording does not stop itself before its timeLimitSeconds cap, so a forgotten one keeps capturing until the cap fires — holding the recording session, wasting disk, and delaying the video you are waiting on (and with trimStatic: false it comes back padded with dead air). Two safety nets exist — use both:
- Set yourself a reminder the moment the recording starts. You know the expected capture length (the interaction you are about to drive). Immediately after
screen-recording-start returns, schedule a wake-up for that expected end time using whatever your harness provides — a built-in reminder/wakeup or scheduled-task tool if you have one, otherwise a background shell running sleep <expected-seconds> whose completion notification pulls you back. When it fires, call screen-recording-stop. Do not rely on remembering.
- Read the tool-result notes. While a recording is running, every argent tool result carries a
NOTE: reminding you it is still going and how to stop it. If the note says the recording already ended (time limit hit), still call screen-recording-stop — that is what hands you the file.
3. Workflow
- Ensure the target device is booted and the app is in the state you want the video to open on (
list-devices, launch-app, argent-device-interact).
- Call
screen-recording-start with udid and a timeLimitSeconds slightly above the expected interaction length (default 180, max 600). Taps and swipes are drawn into the video by default (see the touch-visualizer note below); pass showTouches: false for a clean raw-screen capture.
- Set the end-of-recording reminder described in §2 — this step is not optional.
- Drive the interaction to capture: gestures, navigation, typing (
argent-device-interact). Prefer run-sequence for tight multi-step interactions so tool-call latency does not pad the video.
- Call
screen-recording-stop with the same udid. It returns { video, durationMs, wallClockMs?, trimmedMs?, warning? }; video is an artifact whose resolved path points at the durably-saved file (see below). The video is already final when stop returns (the watermark is stamped during capture, not in a second pass), so stop takes well under a second.
- Check
warning: it reports cap-triggered stops, early encoder exits, a dropped frame stream, and possibly-truncated containers. Verify the file plays (or at least has a sane size) before presenting it to the user.
Where the file lands (durable, not scratch). Unlike most argent artifacts (which live in a disposable temp cache the OS reclaims), a finished recording is saved durably on the client into <project>/.argent/recordings/ — the project being the nearest ancestor of the client's working directory with a .git/package.json/.argent, or ~/.argent/recordings/ when the client isn't inside a project. This holds even for a remote argent link tool-server: the mp4 is written on the client host, not the server. The saved name is screen-recording-<device>-<timestamp>.mp4; if that name is already taken the new file lands beside it as … (2).mp4 rather than overwriting. Because these files persist in the working tree, mention the path to the user (and note that they are untracked — add them to .gitignore or clean them up if they shouldn't be committed).
Static-frame trimming (on by default). Stretches where the screen does not change are collapsed: the first second of each still stretch is kept so pauses read naturally, then unchanged frames are dropped until something moves again (a change of even a couple of pixels counts). So you can leave a recording running across slow steps, waits, or thinking time without padding the clip with dead air — a 40-second session with 5 seconds of real activity comes back as a ~5-7 second video. When trimming removed anything, stop also returns wallClockMs (real elapsed time) and trimmedMs (how much was cut); durationMs is always the length of the video you actually get. Pass trimStatic: false to screen-recording-start when you want a faithful real-time recording (e.g. to measure how long something took on screen).
Touch visualizer (on by default). Every interaction argent drives is drawn straight into the video: a pulse marks each tap, a fading comet trail follows swipes and drags, and paired markers show the two contact points of a pinch or rotate. This makes a recording self-explanatory — a viewer can see where each gesture landed rather than watching the UI react to an invisible finger. It is rendered by simulator-server into the frame stream (nothing is composited host-side), so it costs nothing extra and never appears in a screenshot. Pass showTouches: false to screen-recording-start to record the raw screen with no overlay (e.g. when capturing exactly what the user would see). If simulator-server cannot enable it, the recording still succeeds and stop returns a warning saying touches are not shown.
4. Platform notes and limits
- What can be recorded: anything simulator-server drives — iOS simulators, Android emulators, and physical Android devices. The only length limit is
timeLimitSeconds (max 600).
- The timeline is paced to a steady 30 fps: a device only emits a frame when its screen changes, so captured frames are re-paced onto a fixed timeline rather than bunching up. With static-frame trimming off (
trimStatic: false) that timeline is wall-clock accurate — a completely still screen still comes back as a full-length video (compressing to almost nothing) and durationMs matches the time you actually recorded. With trimming on (the default, see §3) still stretches past the grace window are collapsed, so durationMs is the trimmed video length and wallClockMs carries the real elapsed time.
- Android: records at the device's native resolution; secure screens (DRM, some password fields) come out black.
- Unsupported: tvOS simulators, physical iPhones, Chromium apps, Vega/Fire TV, and remote (
remote:-prefixed) simulators — none of them expose a readable frame stream. For a single still frame use screenshot; for a replayable interaction script use argent-create-flow instead of a video.
- ffmpeg is required: it is the encoder, so
screen-recording-start fails up front with an install hint if it is missing (brew install ffmpeg). It is resolved from PATH plus the usual Homebrew prefixes.
- Watermark: the Argent logo + "By @swmansion" is stamped bottom-left while encoding, faint (20% opacity) and per-pixel contrast-matched to the background (light logo over dark UI, dark logo over light UI). On by default — turn it off with
argent disable video-watermark (re-enable with argent enable video-watermark). The flag is read when the recording starts.
