RoleAssignment
Defined in: console-sdk/src/session/types.ts:147
The session’s device assignment keyed by modality (SDK_PLAN.md §3.6.5).
Sessions are keyed by role (= modality) and inherit a one-device-per-
modality invariant even when the fleet is configured with
onePerModality: false: a single session cannot contain two devices of the
same modality (start() rejects 'session/invalid-plan'). Rationale:
interval role scoping is modality-keyed; same-modality multi-device
sessions are DEFERRED (§10.2).
Build one directly, or derive it from a device list with roleMap.