{
  "title": "Gateway lock",
  "content": "Last updated: 2025-12-11\n\n* Ensure only one gateway instance runs per base port on the same host; additional gateways must use isolated profiles and unique ports.\n* Survive crashes/SIGKILL without leaving stale lock files.\n* Fail fast with a clear error when the control port is already occupied.\n\n* The gateway binds the WebSocket listener (default `ws://127.0.0.1:18789`) immediately on startup using an exclusive TCP listener.\n* If the bind fails with `EADDRINUSE`, startup throws `GatewayLockError(\"another gateway instance is already listening on ws://127.0.0.1:<port>\")`.\n* The OS releases the listener automatically on any process exit, including crashes and SIGKILL—no separate lock file or cleanup step is needed.\n* On shutdown the gateway closes the WebSocket server and underlying HTTP server to free the port promptly.\n\n* If another process holds the port, startup throws `GatewayLockError(\"another gateway instance is already listening on ws://127.0.0.1:<port>\")`.\n* Other bind failures surface as `GatewayLockError(\"failed to bind gateway socket on ws://127.0.0.1:<port>: …\")`.\n\n* If the port is occupied by *another* process, the error is the same; free the port or choose another with `openclaw gateway --port <port>`.\n* The macOS app still maintains its own lightweight PID guard before spawning the gateway; the runtime lock is enforced by the WebSocket bind.",
  "code_samples": [],
  "headings": [
    {
      "level": "h2",
      "text": "Why",
      "id": "why"
    },
    {
      "level": "h2",
      "text": "Mechanism",
      "id": "mechanism"
    },
    {
      "level": "h2",
      "text": "Error surface",
      "id": "error-surface"
    },
    {
      "level": "h2",
      "text": "Operational notes",
      "id": "operational-notes"
    }
  ],
  "url": "llms-txt#gateway-lock",
  "links": []
}