Data model + projection function for the participant grid:
RoomMember — one row in the grid. Combines the static `p`-tag
role (kind-30312) with the dynamic presence flags (kind-10312
aggregator). Carries an `absent` Boolean for "member never
joined" — nostrnests greys them out and we keep parity by
surfacing the flag for the UI to decide.
ParticipantGrid — onStage / audience split.
buildParticipantGrid(participants, presences) — pure projection.
Stage placement is `canSpeak() && onstage != false`, so a speaker
who explicitly emits `onstage=0` (Tier 1 Step 1's "step off the
stage" tag) drops to audience without losing their speaker role.
Pure-audience members (present in the ledger but not p-tagged)
show up in audience with `role = null`.
Tests:
* Host + speaker on stage with matching presence
* Speaker with onstage=0 drops to audience
* Pure listener (no p-tag) lands in audience with role=null
* P-tagged speaker without presence is on stage with absent=true
* Empty inputs produce an empty grid (no crash)
The actual `LazyVerticalGrid` rendering is a follow-up — current
`StagePeopleRow`s already cover the on-stage/audience split
visually; the data model is the substantive piece. Wiring the
VM's `participantGrid: StateFlow<ParticipantGrid>` and switching
the room screen to a grid layout can ship later without changing
the wire contract or tests.
Claude
5cb2351cdb