@iwer/extension-bridge

Local MCP daemon that lets a coding agent (Claude Code, Codex, Cursor, Copilot, Windsurf, Cline, …) drive any WebXR page through the Immersive Web Emulator browser extension — no dev server required.

This package provides the dev-server-free extension MCP bridge (see packages/extension/extension-mcp-bridge-plan.md). It complements IWSDK's project-scoped iwsdk dev MCP bridge.

How it works

Coding agent ──stdio (MCP)──► @iwer/extension-bridge daemon ──ws://127.0.0.1──► IWE extension ──► IWER device.remote

• The agent spawns iwer-bridge serve over stdio (the universal MCP transport).
• The daemon also hosts a loopback WebSocket server (an MV3 extension can only be a WS client, never a server).
• The extension dials in and relays each tool call to the in-page IWER device.remote.

Security: bound to 127.0.0.1 only, Origin/Host validated, and control is gated browser-side by a per-tab Allow prompt before any agent request reaches a page.

Use

Published package:

claude mcp add --scope user iwer -- npx -y @iwer/extension-bridge serve

Local unpublished checkout:

pnpm --filter @iwer/extension-bridge run build

Then use the committed project config at the repository root, .mcp.json, or manually point your agent at:

{
  "mcpServers": {
    "iwer": {
      "command": "node",
      "args": ["packages/extension-bridge/bin/iwer-bridge.mjs", "serve"]
    }
  }
}

Restart your agent, open a WebXR page, enable Immersive Web Emulator from the toolbar, and click Allow when the agent first acts on the page.

Tools

20 tools mapping 1:1 onto IWER device.remote methods — session (xr_accept_session, xr_get_session_status, …), transform (xr_set_transform, xr_look_at, xr_animate_to), input (xr_select, xr_set_input_mode, gamepad), state, SEM world queries (xr_get_world_state, xr_get_objects), and browser_screenshot (returned as a downscaled image). See src/contract.ts.

Commands

• iwer-bridge serve — run the daemon (your agent spawns this).
• iwer-bridge help — show CLI help.

License

MIT.