24860ec3f1
Update SKILL.md to match the latest upstream skill from vercel-labs/agent-browser, adding substantial new capabilities: - Authentication (auth vault, profiles, session persistence, state files) - Command chaining, annotated screenshots, diffing - Security features (content boundaries, domain allowlist, action policy) - iOS Simulator support, Lightpanda engine, downloads, clipboard - JS eval improvements (--stdin, -b for shell safety) - Timeout guidance, config files, session cleanup Add 7 reference docs (commands, authentication, snapshot-refs, session-management, video-recording, profiling, proxy-support) and 3 ready-to-use shell templates. Kept our YAML frontmatter, setup check section, and Playwright MCP comparison table which are unique to our plugin context.
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Profiling
Capture Chrome DevTools performance profiles during browser automation for performance analysis.
Related: commands.md for full command reference, SKILL.md for quick start.
Contents
Basic Profiling
# Start profiling
agent-browser profiler start
# Perform actions
agent-browser navigate https://example.com
agent-browser click "#button"
agent-browser wait 1000
# Stop and save
agent-browser profiler stop ./trace.json
Profiler Commands
# Start profiling with default categories
agent-browser profiler start
# Start with custom trace categories
agent-browser profiler start --categories "devtools.timeline,v8.execute,blink.user_timing"
# Stop profiling and save to file
agent-browser profiler stop ./trace.json
Categories
The --categories flag accepts a comma-separated list of Chrome trace categories. Default categories include:
devtools.timeline-- standard DevTools performance tracesv8.execute-- time spent running JavaScriptblink-- renderer eventsblink.user_timing--performance.mark()/performance.measure()callslatencyInfo-- input-to-latency trackingrenderer.scheduler-- task scheduling and executiontoplevel-- broad-spectrum basic events
Several disabled-by-default-* categories are also included for detailed timeline, call stack, and V8 CPU profiling data.
Use Cases
Diagnosing Slow Page Loads
agent-browser profiler start
agent-browser navigate https://app.example.com
agent-browser wait --load networkidle
agent-browser profiler stop ./page-load-profile.json
Profiling User Interactions
agent-browser navigate https://app.example.com
agent-browser profiler start
agent-browser click "#submit"
agent-browser wait 2000
agent-browser profiler stop ./interaction-profile.json
CI Performance Regression Checks
#!/bin/bash
agent-browser profiler start
agent-browser navigate https://app.example.com
agent-browser wait --load networkidle
agent-browser profiler stop "./profiles/build-${BUILD_ID}.json"
Output Format
The output is a JSON file in Chrome Trace Event format:
{
"traceEvents": [
{ "cat": "devtools.timeline", "name": "RunTask", "ph": "X", "ts": 12345, "dur": 100 },
...
],
"metadata": {
"clock-domain": "LINUX_CLOCK_MONOTONIC"
}
}
The metadata.clock-domain field is set based on the host platform (Linux or macOS). On Windows it is omitted.
Viewing Profiles
Load the output JSON file in any of these tools:
- Chrome DevTools: Performance panel > Load profile (Ctrl+Shift+I > Performance)
- Perfetto UI: https://ui.perfetto.dev/ -- drag and drop the JSON file
- Trace Viewer:
chrome://tracingin any Chromium browser
Limitations
- Only works with Chromium-based browsers (Chrome, Edge). Not supported on Firefox or WebKit.
- Trace data accumulates in memory while profiling is active (capped at 5 million events). Stop profiling promptly after the area of interest.
- Data collection on stop has a 30-second timeout. If the browser is unresponsive, the stop command may fail.