Server Options

npx gasoline-mcp [options]

Options:
  --port <number>        Port to listen on (default: 7890)
  --log-file <path>      Path to log file (default: ~/gasoline-logs.jsonl)
  --max-entries <number> Max log entries before rotation (default: 1000)
  --mcp                  Run in MCP mode for AI tool integration
  --help, -h             Show help message

Log File Auto-Discovery

The extension automatically discovers the log file path from the server. When you use --log-file to set a custom location, the server reports the actual path via its /health endpoint. The extension popup displays the correct path under “Server Info.”

Log Rotation

The default limit is 1000 entries. When reached, the oldest entries are removed.

Why 1000?

With enrichments enabled, a single error can generate multiple entries:

Entry Type Per Error Typical Size
Error/exception 1 ~1-2 KB
Network waterfall 1 ~10-30 KB
Performance marks 1 ~5-10 KB
Screenshot 1 ~0.1 KB (filename reference)
User actions included ~1-2 KB

A fully-enriched error = ~4 entries, so 1000 entries = ~250 fully-enriched errors. For a typical debugging session (10-50 errors), this provides ample history.

Increase for Verbose Logging

npx gasoline-mcp --max-entries 5000

Decrease for Constrained Disk

npx gasoline-mcp --max-entries 200

Extension Settings

Click the Gasoline extension icon to configure:

Capture Level

  • Errors Only — console.error, network failures, exceptions
  • Warnings+ — errors plus console.warn
  • All Logs — everything including console.log, info, debug

Advanced Features

Toggle these independently:

  • WebSocket monitoring — connection lifecycle and messages
  • Network waterfall — request timing data
  • Performance marks — performance.mark() and measure()
  • User actions — click/input/scroll buffer
  • Screenshot on error — auto-capture on exceptions
  • Source maps — resolve minified stack traces

WebSocket Capture Mode

  • Lifecycle only — open/close events
  • Include messages — message payloads with adaptive sampling

Domain Filters

In Options, configure which domains to capture from. This prevents noise from third-party scripts and analytics.

Custom Port

If port 7890 is in use:

npx gasoline-mcp --port 7891

Then update the extension:

  1. Click the Gasoline icon
  2. Click “Options”
  3. Change Server URL to http://localhost:7891
  4. Click “Save Options”