site-motion-capture

This MCP server captures live website motion on the rented Vast.ai GPU VM. It uses the existing Playwright recorder on that VM and copies the WebM video and jank report to the local machine.

Use design-inspiration to find candidate sites. Use this server after a site has been selected and its live behavior needs inspection.

In Antigravity, pass the returned local .webm path directly to native video understanding for the motion analysis step. Do not start the standalone gemini-vision MCP or upload the recording through the Gemini API for this workflow. Ask the native analyzer for a concise description and at most eight timestamped moments using the shape { description, moments: [{ timestamp_s, why }] }, then use those timestamps for frame extraction and implementation planning.

Tools

• capture_site_motion records page load, scroll, and optional hover or click behavior. Desktop captures default to 1920×1080. It returns local and remote artifact paths. The MCP keeps Playwright's WebM encoder at an 8 Mbps target so text and fine UI details remain readable. It rejects non-essential cookie consent by default and records the action in the jank report.

• check_capture_gpu checks both nvidia-smi and the Chromium WebGL renderer.

Related MCP server: EasyPlaywrightMCP

Consent and interaction policy

Captures use consent_mode: "reject" by default. The public options are:

• reject rejects non-essential cookies and records the action.

• accept accepts all cookies only when consent_accept_approved: true is supplied explicitly. It fails closed otherwise.

• none leaves the page untouched and does not attempt consent handling.

• granular applies the settings, optional-cookie, and save selectors in order.

The recorder uses an unrecorded preflight context, then carries its storage state into the recorded context. It checks both contexts, including child frames. For reject, accept, and granular, a result is verified only when the consent surface is gone after the required action. dismissed is then true. If no safe control was found, the outcome is no-safe-action. If a surface remains or a blind spot prevents verification, the result is not verified. In none mode, no dialog means verified: true, dismissed: false, and outcome no-consent-surface. A present dialog means verified: false, dismissed: false, and outcome consent-surface-present. If a page blocks consent or scroll inspection, the recorder bounds that check and reports consent-check-timeout with a blind-spot entry; the video can still be published, but it must not be treated as consent-verified. The report keeps the mode, action, selector, phase, frame, reason, attempts, budget, and click count.

For an unusual control, pass consent_selector. It must be an explicit, stable CSS selector for the intended control. The same rule applies to hover_selector and click_selector. Selectors do not cross iframe boundaries. Automatic detection can miss shadow-DOM controls and controls hidden behind closed shadow roots.

consent_wait_ms sets how long the recorder waits for the dialog. Set consent_preflight: false to skip the unrecorded pass. Localization guidance must be written in English and include an explicit selector for each localized control. Do not depend on translated visible text alone.

Keep each capture within the 8-second interaction budget. The default discovery pass uses at most six clicks. Add explicit selectors for required interactions outside that pass. Automatic discovery is best-effort and does not prove that every interaction was captured.

The local name is a stable file stem for the copied .webm and .jank.json files. It is not the remote run ID. Keep the local name stable when comparing runs. Use the remote run ID for remote logs and cleanup. Unless output_dir or SITE_MOTION_OUTPUT_DIR is supplied, local artifacts are saved under artifacts/design-inspiration/site-motion-capture/ in the MCP client's current workspace. Use overwrite: false when available so an existing local capture is preserved. Cleanup reports one status per artifact: removed, missing, skipped, or failed. A cleanup failure does not mean that the capture failed.

Runtime

The server has no npm dependencies. The launcher sources ~/.zsh_secrets for the Vast API key and the Vast CLI environment. The API key does not appear in the MCP configuration.

The launcher resolves the SSH endpoint for instance 48790763 with the Vast CLI. Override it with VAST_INSTANCE_ID or SITE_MOTION_SSH_URL when the capture VM changes.

The remote recorder must exist at /workspace/site-motion-capture and must provide capture.mjs and check-gpu-renderer.mjs.