Data Flow — Azan Delivery

:::info Status Implemented. Source: docs/azan-flow.md, docs/live-broadcast-flow.md. :::

Every prayer time, exactly one of two paths delivers the azan to mosque speakers (ESP32), member phones, and web listeners — the scheduler guarantees never both.

Path A — Live azan

1. Admin (or a transmitter's audio uplink) opens wss://host/ws/broadcast/{mosque_id}/azaan?token=BROADCAST_TOKEN.
2. First connection for that mosque+room sets the in-memory "on air" flag (active_broadcasters["{m}:azaan"]), spawns FFmpeg piping stdin to the Icecast mount, and fires the started fan-out (core/live_broadcast.py:notify_icecast_broadcast_started).
3. Disconnect or BROADCAST_IDLE_TIMEOUT_SECS (default 60s) of silence ends the broadcast: FFmpeg killed, flag cleared, ended fan-out fires.

Full detail: Azaan Broadcast module.

Path B — Offline azan (scheduler fallback)

core/azan_scheduler.py ticks every AZAN_AUTO_CHECK_INTERVAL_SECS (default 60s), started in the FastAPI lifespan. For each active mosque and enabled prayer inside the [grace, window] minutes window:

1. Checks three independent signals for "already handled" — the live on-air flag, a recent triggers row, a recent broadcast_audit_logs row — so a live azan (or a server restart mid-window) never causes a duplicate.
2. If not handled: picks the mosque's uploaded recording (Fajr voice for Fajr, general recording otherwise), starts an Icecast file stream via FFmpeg -re, then fires the same MQTT + push fan-out a live azan would.

Full detail: Azaan Broadcast module.

Fan-out (both paths, in parallel)

Channel	Recipient	Detail
MQTT play command, per device	Every stream player and transmitter bound to the mosque	MQTT commands
iOS VoIP push (PushKit)	Members' iPhones	Rings like a call via CallKit
Android data-only FCM	Members' Android phones	Native call UI
broadcast_audit_logs row	—	Delivery analytics; see Broadcast Audit module

Non-azaan live broadcasts (e.g. a khutbah/announcement) skip device MQTT delivery entirely and use ordinary alert/notification push instead of the call-style VoIP/FCM path — see Azaan Broadcast module §fan-out.

Race handling

The scheduler and a live broadcast can never both fire for the same (mosque, date, prayer) slot — see the race table in Azaan Broadcast module.