ReadonlyidThe detected device id (reac:stagebox, or a discriminated reac:stagebox:<key>).
Optional ReadonlylinkThe box's live link state (reac.link-state): 'probing', 'connected', or
'no-box'. Drives the stagebox card's link badge + the session-manifest presence check
(issue #154). Absent when reac-pw does not publish it (older reac-pw, non-REAC).
Optional ReadonlymodelThe box model (reac.box-model, e.g. S-4000S) — recorded in the session manifest.
Optional ReadonlywidthThe box channel width (reac.box-width) — the expected I/O count in the manifest.
A detected reac-pw stagebox as the diff reads it now — its id + the live link/box props.