# M3 Hardware Loop Fixture

`topology.json` is the local contract fixture for the M3 hardware trusted loop
smoke. It models two simulated boxes, two simulated gateways, and one patch
panel.

The only active cross-device wiring is:

```text
box-simu-1 DO1 -> box-simu-2 DI1
```

The smoke script reads this fixture and calls the patch-panel model directly.
It does not start services, deploy DEV/PROD, access real hardware, read
secrets, or write audit rows to a database.
