refactor(mobile): drop the dead all-hosts client broadcast

Moving notification ownership to the root owner left subscribeAllHosts with
no consumers. It re-renders every subscriber on any host's open/close, so
leaving it wired is a standing invitation to reintroduce the O(N) fanout this
change removes. Per-host notifyHostState already covers every store mutation.

Co-authored-by: Orca <help@stably.ai>

mobile/src/transport/client-context.tsx

@@ -17,10 +17,8 @@ import { decrementPendingAcquisition } from './host-client-acquisition-count'
 import { subscribeHostClientRevival } from './host-client-revival-scheduler'
 import {
   clientActivePath,
-  notifyAllHostListeners,
   notifyHostStateListeners,
   primeHostProfiles,
-  subscribeAllHostListener,
   subscribeHostStateListener,
   type CloseEntryOptions
 } from './host-client-context-state'
@@ -52,7 +50,6 @@ export type RpcClientContextValue = {
   getActivePath: (hostId: string) => MobileConnectionPath
   getClient: (hostId: string) => RpcClient | null
   subscribeHostState: (hostId: string, listener: (state: ConnectionState) => void) => () => void
-  subscribeAllHosts: (listener: () => void) => () => void
   // Why: lets the home screen feed already-loaded HostProfiles so we don't pay loadHosts() latency twice.
   primeHosts: (hosts: HostProfile[]) => void
 }
@@ -63,7 +60,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
   // Why: entries in a ref so state changes don't re-render the whole tree; propagation goes through per-host listener Sets.
   const storeRef = useRef<Map<string, StoreEntry>>(new Map())
   const stateListenersRef = useRef<Map<string, Set<(state: ConnectionState) => void>>>(new Map())
-  const allHostsListenersRef = useRef<Set<() => void>>(new Set())
 
   // Pending opens keyed by hostId so two acquire() callers in the same render don't race the host lookup.
   const pendingOpensRef = useRef(new HostClientOpenRegistry())
@@ -74,7 +70,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
 
   const notifyHostState = (hostId: string, state: ConnectionState) =>
     notifyHostStateListeners(stateListenersRef.current, hostId, state)
-  const notifyAllHosts = () => notifyAllHostListeners(allHostsListenersRef.current)
 
   const closeEntry = useCallback((hostId: string, options: CloseEntryOptions) => {
     const entry = storeRef.current.get(hostId)
@@ -92,7 +87,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
     storeRef.current.delete(hostId)
     entry?.client.close()
     notifyHostState(hostId, 'disconnected')
-    notifyAllHosts()
   }, [])
 
   const closeHost = useCallback(
@@ -126,13 +120,11 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
         } catch {
           // Why: cold-start Keychain failure (iOS mid-unlock / Android Keystore race); surface 'disconnected' so the user can Reconnect.
           notifyHostState(hostId, 'disconnected')
-          notifyAllHosts()
           return null
         }
         if (!host) {
           // Why: silent return leaves screens on a permanent spinner (STA-1511); surface 'disconnected' so they show a retry affordance.
           notifyHostState(hostId, 'disconnected')
-          notifyAllHosts()
           return null
         }
       }
@@ -153,7 +145,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
       } catch {
         // Why: openHostLogicalClient can throw synchronously (bad public key / invalid URL); notify so the UI leaves 'connecting'.
         notifyHostState(hostId, 'disconnected')
-        notifyAllHosts()
         return null
       }
       const unsubState = client.onStateChange((state) => {
@@ -173,7 +164,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
       pendingAcquisitionsRef.current.delete(hostId)
       storeRef.current.set(hostId, entry)
       notifyHostState(hostId, entry.state)
-      notifyAllHosts()
       return entry
     } finally {
       pendingOpensRef.current.deleteIfCurrent(hostId, pendingOpen)
@@ -312,11 +302,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
     []
   )
 
-  const subscribeAllHosts = useCallback(
-    (listener: () => void) => subscribeAllHostListener(allHostsListenersRef.current, listener),
-    []
-  )
-
   // Close all clients on provider unmount. Empty deps: [closeEntry] would let Fast Refresh tear down all live sockets.
   // eslint-disable-next-line react-hooks/exhaustive-deps
   useEffect(() => {
@@ -352,7 +337,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
       getActivePath,
       getClient,
       subscribeHostState,
-      subscribeAllHosts,
       primeHosts
     }),
     [
@@ -369,7 +353,6 @@ export function RpcClientProvider({ children }: { children: ReactNode }) {
       getActivePath,
       getClient,
       subscribeHostState,
-      subscribeAllHosts,
       primeHosts
     ]
   )

mobile/src/transport/host-client-context-state.ts

@@ -17,12 +17,6 @@ export function notifyHostStateListeners(
   }
 }
 
-export function notifyAllHostListeners(listeners: Set<() => void>): void {
-  for (const listener of listeners) {
-    listener()
-  }
-}
-
 export function subscribeHostStateListener(
   listeners: Map<string, Set<(state: ConnectionState) => void>>,
   hostId: string,
@@ -42,20 +36,6 @@ export function subscribeHostStateListener(
   }
 }
 
-export function subscribeAllHostListener(
-  listeners: Set<() => void>,
-  listener: () => void
-): () => void {
-  listeners.add(listener)
-  return () => listeners.delete(listener)
-}
-
-export function listHostClients(
-  entries: ReadonlyMap<string, { client: RpcClient }>
-): { hostId: string; client: RpcClient }[] {
-  return [...entries].map(([hostId, entry]) => ({ hostId, client: entry.client }))
-}
-
 export function primeHostProfiles(cache: Map<string, HostProfile>, hosts: HostProfile[]): void {
   for (const host of hosts) {
     cache.set(host.id, host)