feat(scale): swappable pub/sub layer + fix chat.js missed awaits (Phase 6)

Two things:

1. FIX a live regression the async conversion missed: chat.js calls repos via the
   lazy repos() helper (not the R. prefix), so my sweep skipped it — effectiveStatus
   / broadcastPresence read `repos().users.byId(userId)` synchronously, but that's a
   Promise now, so presence broadcasts always reported status 'active' and dropped
   last_seen. Now awaited (effectiveStatus/broadcastPresence async); touchSeen is a
   fire-and-forget UPDATE with .catch. Audited all non-R. repo calls — only chat.js
   was affected (media.js backfill was already awaited).

2. Swappable pub/sub for multi-instance real-time fan-out (the actual blocker to
   running >1 instance — not the DB). server/pubsub.js picks a backend by
   PUBSUB_BACKEND (default 'memory'). Local socket delivery is UNCHANGED; publish is
   additive — memory = no-op (zero hot-path cost, identical single-instance
   behaviour), redis = fan-out to other instances with a self-echo guard. chat.js
   pushToUser/broadcastPresence now also publish; each instance subscribes to deliver
   remote events to its local sockets. Interface is tiny so Redis is one swappable
   file (Postgres LISTEN/NOTIFY or NATS could drop in the same way — never hardwired,
   as requested). Dormant redis service added to compose behind the 'scale' profile;
   redis dep added; PUBSUB_BACKEND/REDIS_URL documented.

Validated: smoke 22/22 (memory), e2e chat delivery green. NOTE: full multi-instance
also needs distributed presence (isOnline is per-process) + meeting-signaling
sharing — chat/presence fan out via this layer; those are follow-ups.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

This commit is contained in:

Sravan

2026-07-24 23:20:02 +05:30

parent 363c4a539f

commit 63f2c588da

8 changed files with 137 additions and 24 deletions

									
										.env.example
									
		+6
		
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				@@ -36,3 +36,9 @@ TURN_CREDENTIAL=

				# POSTGRES_PASSWORD=

				# DATABASE_URL=postgres://bizgaze:PASSWORD@bizgaze-postgres:5432/bizgaze

				# DB_BACKEND=pg

				# Optional: cross-instance real-time (chat/presence) fan-out via Redis, for running MULTIPLE app instances.

				# Leave unset for single-instance (in-memory pub/sub, the default). To scale out: start the redis service

				# (`docker compose --profile scale up -d`), then set both below + a sticky load balancer for /ws.

				# PUBSUB_BACKEND=redis

				# REDIS_URL=redis://bizgaze-redis:6379