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# `@maka/computer-use`

`@maka/computer-use` adapts Maka's Runtime-owned Computer Use contracts to the
native `maka-cu` executor. It owns backend selection, the executor process and
protocol lifecycle, host-side result decoding, display snapshot mapping, and
the cursor-overlay hook. Runtime owns the model-facing tools and session state;
Desktop supplies the executable and presentation dependencies.

## Public seam

The package exposes one root entry point through `src/index.ts`:

- `selectComputerUseBackend()` selects the available executor and builds the
  Runtime tool set. `CU_BACKEND_IDS` currently contains only `maka-cu`.
- `createMakaCuBackend()` adapts the native executor to Runtime's
  `CuDispatchBackend` contract.
- `MakaCuService` supervises the executor process and owns the JSON-RPC request,
  cancellation, restart, and generation lifecycle.
- The `maka-cu-protocol` exports decode and validate `maka.cu/2` envelopes,
  snapshots, dispatch results, domain errors, and key chords.
- `resolveCuaDisplaySnapshots()` maps executor screenshots to Electron display
  coordinates without guessing when the display geometry is ambiguous.
- `createComputerUseOverlayHook()` projects action lifecycle events to a
  presentation-only cursor sink. It does not choose or authorize targets.

Other packages should import these exports from `@maka/computer-use`, not from
undeclared internal source paths.

## Current platform boundary

The shipped selector enables Computer Use only when all of these conditions
hold:

1. the host platform is macOS (`process.platform === 'darwin'`);
2. the composition supplies a `maka-cu` executable path; and
3. the composition supplies the executable's expected SHA-256 digest.

On another platform, with missing inputs, or when backend construction fails,
selection fails closed to `backendId: 'none'` with an empty tool set. This
package does not discover, download, or choose an unpinned executable.

The executable's build, provenance, signing, and distribution status are
separate release concerns. See
[`computer-use-provenance.md`](../../docs/computer-use-provenance.md) rather
than assuming that installing this workspace supplies a runnable binary.

Cross-platform work is tracked separately:

- [#3896](https://github.com/apache/maka/issues/3896) — platform abstraction;
- [#3891](https://github.com/apache/maka/issues/3891) — Linux backend;
- [#3785](https://github.com/apache/maka/issues/3785) — Windows executor
  hardening and production evidence.

## Protocol and lifecycle

The host and executor communicate over line-delimited JSON-RPC using the
versioned `maka.cu/2` protocol. `MakaCuService` verifies that the executable is
usable and checks any configured digest before spawning it, completes a
`host.hello` handshake, and exposes the executor version, capabilities, limits,
and process generation. The product selector always supplies the required
digest.

Lifecycle and protocol failures remain distinct:

- `MakaCuLifecycleError` reports unavailable, mismatched, aborted, or
  outcome-unknown process states;
- `MakaCuRpcError` reports a JSON-RPC error response for one method; and
- `MakaCuProtocolViolation` reports malformed or contradictory wire data.

An executor exit releases affected sessions and invalidates their observations.
Requests that may have reached the executor surface as outcome-unknown rather
than being replayed automatically. Runtime must re-observe before another
action.

## Ownership rules

- Keep provider-neutral Computer Use types and model-facing contracts in
  `@maka/core` and `@maka/runtime`.
- Keep native executor transport, decoding, and lifecycle handling in this
  package.
- Keep Electron windows, screen-lock integration, binary provisioning, and
  product status UI in `apps/desktop`.
- Add a second backend only after it has a real adapter and platform evidence;
  do not widen `CU_BACKEND_IDS` with a placeholder.
- Preserve fail-closed selection and snapshot-bound dispatch. Missing or stale
  authority must not fall back to global pointer or foreground input.

The cross-layer safety and evidence rules live in the
[`Computer Use foundation contract`](../../docs/computer-use-foundation-contract.md)
and [`host events contract`](../../docs/computer-use-host-events-contract.md).

## Verification

Install dependencies once at the repository root, then run:

```sh
npm run build
npm --workspace @maka/computer-use run test:dist
npm --workspace @maka/computer-use run typecheck
```

The package tests cover protocol decoding, process lifecycle, backend behavior,
host-event propagation, display mapping, overlay projection, and the cumulative
Computer Use path.