Relocate the session-management apply + renderer-liveness logic into
qconnect-app so both the Tauri and the future Slint adapter share it:
- apply_session_management_event(message_type, payload, identity)
-> SessionApplyOutcome: the locked critical section, byte-identical,
now locking self.sync. Local identity is injected as data (LocalIdentity)
so the crate stays frontend-agnostic (refresh_local_renderer_id takes it
instead of resolving device-info itself). The CoreBridge post-lock work is
RETURNED via the outcome rather than run inline -- materialization stays
adapter-side (renderer-engine seam, slice 6). Early returns yield a default
outcome, exactly as the prior `return;` skipped the post-lock block.
- arm_renderer_watchdog / run_renderer_watchdog: the generation-guarded 12s
liveness task, modeled on watch_pending_action_timeout (tokio::spawn + sleep
+ re-lock + 4-field epoch revalidation).
- freeze_active_renderer_projection: cached playing_state -> UNKNOWN, then
emit the freeze event through the sink (dedicated channel + blanket event
preserved).
- ensure_session_renderer_state + sync_session_renderer_active_flags moved to
qconnect-app (pure mutators over the relocated accumulator).
Adds 5 tests (SESSION_STATE outcome, watchdog arm/fire-after-12s/epoch-disarm,
ACTIVE_DISCONNECTED freeze) using start_paused + advance. The Tauri sink keeps
its own live copy this commit; slice 2+4.5 rewires it to delegate and deletes
the duplicate. qconnect-app 38 green, src-tauri qconnect 42 green.
cc
vicrodh
77717546fb