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MCP module

What it does

MCP presents NOW's two local client transports and the selected classic Mac's explicit ceiling on what an agent may observe or change. Both transports use one catalog and dispatcher inside NOW; there is no separately installed MCP service.

The macOS MCP module showing transport and grant state

Availability

The host app owns both transports and all projections. PowerPC provides the machine consent page. NOW-68K does not expose this MCP consent surface.

On the modern Mac

The host exposes independent controls for:

  • Standard Input, a narrow New Old World --mcp-stdio process launched by an MCP client. Its card copies the executable command and shows the private same-user socket it uses to reach the already-running app.
  • HTTP, an authenticated loopback listener running directly inside the normal NOW app. Its card shows the URL and copies the bearer token without rendering the secret in the module or logs.

The module also shows the shared catalog, selected machine, available capabilities, grant state, and auditable calls. A running transport is not a machine grant.

On the classic Mac

The PowerPC MCP page sets the machine's ceiling. It cannot supply host-local credentials or prove that an MCP client can reach the host.

The PowerPC MCP consent page

Common tasks

  • Confirm the selected machine and requested capability before granting.
  • Start only the transport required by the client. HTTP is off by default; stdio remains available by default for client-launched sessions.
  • Copy connection details from the relevant transport card rather than locating a helper executable.
  • Read the recent call record after an agent action.

Global transport availability, HTTP authentication, and per-machine grants are separate controls. Do not weaken the same-user socket, loopback bind, bearer, Host, Origin, session, or framing limits to connect a client.

Failure states

Transport stopped, local socket unavailable, HTTP authentication failure, not addressed, not granted, capability unavailable, stale reference, and machine refusal are typed.

Current limitations

The 68K guest has no matching consent UI. Experimental semantic tools inherit Mirror's narrower observation and act evidence.

For developers

See agent boundary and MCP coverage.