Introduces the data model + in-memory dedup/eviction logic the
participant grid (Tier 2 #1), hand-raise queue (T1 #5), and listener
counter (T1 #8) all consume.
RoomPresence — one peer's most recent kind-10312 snapshot.
Equality is by pubkey alone so a Set or Map
swap on heartbeat update doesn't double-count
when only the timestamp changes.
`RoomPresence.from(event)` projects every
presence tag, with conservative defaults for
absent ones (handRaised/publishing default
false; muted stays null to distinguish "didn't
say" from "explicitly false"; onstage defaults
TRUE so pre-onstage clients still render as
speakers).
RoomPresenceAggregator
— `apply(event)` dedupes by pubkey, keeps the
most recent createdAt (out-of-order events
can't overwrite newer state). `evictOlderThan`
is the staleness sweep — caller drives the
cadence (typically a 60 s tick passing
`now - 6*60` to evict on >6 min of silence).
Tests cover: tag projection, the absent-tag defaults, dedup on same
pubkey, out-of-order non-overwrite, multi-pubkey isolation, eviction
window, and the pubkey-only equality contract.
The amethyst-side LocalCache wiring + listener-counter UI come next
in their own commit.
Claude
87dd8ee2ec