Module notify_router 

Daemon-mode phase 2 (C3): extension notification router.

One subscriber per loaded extension (ProcessExtension::subscribe_notifications), started ONCE by the host after discovery; forwards widget.* frames (super::widgets::is_widget_method) to every live session as SessionEventWire::ExtensionNotification via crate::host::EngineHost::broadcast_extension_notification.

Routing (phase 3, C2): a frame whose params.session_id is a string is delivered to THAT session only (dropped with a debug! if it is not live); a frame without one is daemon-global and goes to every session (the pre-phase-3 behaviour — docs/extensions/session-id.md §plugin contract). Delivery is non-blocking: a session whose command queue is full drops the frame with a warn! — widget upserts are idempotent last-writer-wins UI state (loop_arms.rs semantics), and blocking would backpressure the extension’s lossless fan-out and stall command.invoke / provider.stream subscribers on the same queue.

The inline TUI keeps its own watcher (loop_arms.rs) today; this router serves actor-hosted sessions (daemon, synaps chat on the actor).

Functions

forward_extension_notifications

Forward loop for ONE extension. Exits when the extension has been unloaded from the manager (its channel closed and it is no longer listed); otherwise resubscribes after [RESUBSCRIBE_DELAY].

route_target

params.session_id when it is a non-empty string — the frame is session-scoped; otherwise daemon-global (broadcast).

spawn_notification_router

Start one forwarding task per loaded extension. Idempotent per call site by construction — the host calls it once after extensions_ready(); call it again only after a genuine re-discovery. The returned handle completes once every per-extension task has been spawned (the tasks themselves run for the host’s lifetime and end when their extension is gone and stays gone).