MockScale never emits again after a disconnect, blocking auxiliary-scale testing

Start with lib/src/models/device/impl/mock_scale/mock_scale.dart, focusing on simulateDisconnect(), onConnect(), and _startEmission(). Compare the reconnect behavior with MockBengle and MockDe1, then verify that disconnecting and reconnecting MockScale produces subsequent snapshot frames on /ws/v1/scales/MockScale/snapshot.

Summary

MockScale stops emitting snapshots the first time it is disconnected and never starts again for the life of the process. Anything that needs a simulated scale to be disconnected and reconnected — the auxiliary scale role most of all — cannot be exercised end to end.

Why

lib/src/models/device/impl/mock_scale/mock_scale.dart

@override
disconnect() async {
  simulateDisconnect();
}

void simulateDisconnect() {
  _stalled = true;
  _emissionTimer?.cancel();
  _emissionTimer = null;
  detachMachine();
  _connectionSubject.add(ConnectionState.disconnected);
}

_startEmission() is called only from the constructor. onConnect() adds ConnectionState.connected and nothing else — it does not clear _stalled and does not restart the timer:

@override
Future<void> onConnect() async {
  _connectionSubject.add(ConnectionState.connected);
}

So after one disconnect() the scale reports itself connected again, the registry opens a session, /ws/v1/scales/MockScale/snapshot sends {"status":"connected"} — and no weight ever follows.

How it showed up

Verifying that a skin's dosing-scale feature works against the auxiliary role on 0.8.7-beta.1. The control plane is all correct:

• GET /api/v1/devices reports connectionRole, and the connected primary is correctly excluded from what a skin may offer as a second scale
• PUT /api/v1/devices/connect {connectionRole: "auxiliary"} after releasing it: role comes back auxiliary
• PUT /api/v1/scales/MockScale/tare on the auxiliary session: 200
• preferredScaleId is untouched throughout, as the contract requires
• asking for auxiliary while it is still claimed as primary: 409 conflict

The data plane could not be checked at all:

ws://.../ws/v1/scales/MockScale/snapshot
[1] {"status":"connected"}
4 seconds, 1 frame total

MockScale emits every 200 ms from a broadcast controller, and _Session.start() subscribes to scale.currentSnapshot correctly, so nothing in the registry or the handler is at fault — the source had simply been switched off by the earlier disconnect.

There is no way around it on a simulated setup: the scale auto-connects as primary at startup even with preferredScaleId cleared, and the only route to the auxiliary role goes through a disconnect, which is what kills the emitter.

Suggested fix

Have onConnect() undo what simulateDisconnect() did:

@override
Future<void> onConnect() async {
  _stalled = false;
  _startEmission();
  _connectionSubject.add(ConnectionState.connected);
}

_startEmission() already cancels any existing timer, so calling it again is safe. MockBengle and MockDe1 are worth a look for the same shape.