fix(mobile): recover when half-open sockets omit close events (#11368)

* fix(mobile): recover half-open RPC sockets

* test(mobile): assert reconnect attempt reset

* fix(mobile): coalesce half-open recovery probes

---------

Co-authored-by: OrcaWin <293788423+OrcaWin@users.noreply.github.com>

mobile/src/transport/rpc-client.test.ts

@@ -707,6 +707,47 @@ describe('mobile rpc-client connection timeout', () => {
       client.close()
     })
 
+    it('reconnects when the half-open socket omits its close callback', async () => {
+      const client = connect('ws://desktop.invalid', 'token', 'server-key')
+      const socket = mockSockets[0]!
+      openAndAuthenticate(socket)
+      socket.emitCloseOnClose = false
+
+      client.notifyForeground()
+      await vi.advanceTimersByTimeAsync(8_000)
+
+      expect(socket.close).toHaveBeenCalledTimes(1)
+      expect(client.getState()).toBe('reconnecting')
+      socket.onclose?.()
+      expect(client.getState()).toBe('reconnecting')
+
+      await vi.advanceTimersByTimeAsync(500)
+      expect(mockSockets).toHaveLength(2)
+      openAndAuthenticate(mockSockets[1]!)
+      expect(client.getState()).toBe('connected')
+      expect(client.getReconnectAttempt()).toBe(0)
+
+      await vi.advanceTimersByTimeAsync(1_000)
+      expect(mockSockets).toHaveLength(2)
+
+      client.close()
+    })
+
+    it('coalesces repeated foreground probes while one probe is pending', async () => {
+      const client = connectAuthenticated().client
+      const socket = mockSockets[0]!
+      client.notifyForeground()
+      client.notifyForeground()
+      client.notifyForeground()
+      expect(sentRequests(socket, 'status.get')).toHaveLength(1)
+      await vi.advanceTimersByTimeAsync(8_000)
+      expect(socket.close).toHaveBeenCalledTimes(1)
+      expect(client.getState()).toBe('reconnecting')
+
+      await vi.advanceTimersByTimeAsync(500)
+      expect(mockSockets).toHaveLength(2)
+      client.close()
+    })
     it('keeps a healthy connection when the foreground probe is answered', async () => {
       const { client, socket } = connectAuthenticated()
 

mobile/src/transport/rpc-client.ts

@@ -161,6 +161,7 @@ export function connect(
   let connectTimer: ReturnType<typeof setTimeout> | null = null
   let handshakeTimer: ReturnType<typeof setTimeout> | null = null
   let activityProbeTimer: ReturnType<typeof setInterval> | null = null
+  let activityProbeInFlight = false
   let intentionallyClosed = false
   // Consecutive auth rejections; tolerate up to AUTH_RETRY_BUDGET (issue #5200) before latching to avoid a needless re-pair.
   let authRejectionCount = 0
@@ -768,15 +769,17 @@ export function connect(
 
   // Why: app-level liveness probe (see ACTIVITY_PROBE_INTERVAL_MS) — force-closes the WS on failure so onclose reconnects.
   function runActivityProbe() {
-    if (state !== 'connected' || !ws) {
+    if (state !== 'connected' || !ws || activityProbeInFlight) {
       return
     }
+    activityProbeInFlight = true
     const probeWs = ws
     const id = nextId()
     const probeInboundSequence = inboundSequence
     let timedOut = false
     const timeout = setTimeout(() => {
       timedOut = true
+      activityProbeInFlight = false
       pending.delete(id)
       if (inboundSequence > probeInboundSequence) {
         return
@@ -785,6 +788,10 @@ export function connect(
       // Why: stale probe timers must not close a replacement socket.
       if (probeWs === ws && probeWs.readyState === WebSocket.OPEN) {
         probeWs.close()
+        // Why: React Native can omit onclose for a wedged iOS transport.
+        if (probeWs === ws) {
+          handleSocketClosed(probeWs, { timedOut: true })
+        }
       }
     }, 8_000)
     pending.set(id, {
@@ -792,16 +799,19 @@ export function connect(
         if (timedOut) {
           return
         }
+        activityProbeInFlight = false
         clearTimeout(timeout)
       },
       reject: () => {
         if (timedOut) {
           return
         }
+        activityProbeInFlight = false
         clearTimeout(timeout)
       }
     })
     if (!sendEncrypted({ id, deviceToken, method: 'status.get' })) {
+      activityProbeInFlight = false
       clearTimeout(timeout)
       pending.delete(id)
     }