# Console-free, headless-first execution

## Behavior

Windows child processes are launched with `CREATE_NO_WINDOW` and a `STARTUPINFO`
request for `SW_HIDE`. GUI automation starts on an off-screen Win32 desktop; Linux
automation starts on Xvfb. Windows stdio compatibility clients and any explicitly
opted-in legacy HTTP service invoke the server through `pythonw.exe`. The Cheap
Version is the primary local route and does not start a persistent server.

Foreground pointer, keyboard, window-action, window-reveal, UAC, and desktop-switch
operations are blocked unless `confirm_focus_disruption=true`. That confirmation
is valid only after the user explicitly requests an interactive handoff. On Linux,
background clicking is focus-safe only when an Xvfb `display` is supplied.

## Configuration

- `install-startup` is retired and refuses to create a launcher.
- `install-startup --legacy-http` explicitly opts into the old UTF-16 VBS or
  elevated Scheduled Task path for a compatibility client.
- The default local path is `lowlevel-computer-use-cheap`; the compatibility
  endpoint remains `http://127.0.0.1:8765/mcp` only when started explicitly.
- Claude, Codex, and OpenCode registrations should use the active environment's
  `pythonw.exe`, not `uv.exe` or a console-script `.exe`.

## Failure modes

- If `pythonw.exe` is unavailable, installation fails closed instead of falling
  back to a console executable.
- Applications using raw input may reject background messages. Report that
  limitation instead of activating their visible window.
- A user-approved UAC prompt or desktop reveal necessarily interrupts focus; the
  default guards prevent accidental use.
- Windows Script Host requires the startup script's UTF-16 BOM. UTF-8 scripts may
  return status 1 without useful diagnostics.

## Security

The HTTP server binds to localhost by default and has no application-layer
authentication. Do not expose it to another interface without an authenticated
reverse proxy and explicit network review. Patterns, samples, screenshots, and
command output remain local unless another tool explicitly sends them elsewhere.

## Verification

`tests/test_focus_and_process_safety.py` checks process flags, protected tools,
retired-startup refusal, explicit legacy startup generation, and headless-first
MCP instructions. `tests/test_cheap_entry.py` checks the bounded Cheap Version
catalog and legacy registration migration. Live Windows verification records the
foreground HWND before and after launching a real off-screen GUI and, only when
needed for compatibility, the `pythonw.exe` HTTP service; it checks that the
handle is unchanged and enumerates zero top-level windows for the server process.