fix(mobile): keep an unhealthy Force Reconnect replacement

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

@@ -739,6 +739,32 @@ describe('useHostClient', () => {
     harness.unmount()
   })
 
+  it('keeps a live replacement bound when Force Reconnect reports it unhealthy', async () => {
+    const stale = makeFakeClient('connected')
+    const fresh = makeFakeClient('connected')
+    fresh.sendRequest = vi.fn(async () => {
+      throw new Error('Application RPC channel is still not responding')
+    })
+    connectMock.mockReturnValueOnce(stale).mockReturnValueOnce(fresh)
+    loadHostsMock.mockResolvedValue([HOST])
+
+    const harness = await renderHarness(HOST.id)
+    await act(async () => {
+      await expect(harness.forceReconnect(HOST.id)).rejects.toThrow(
+        'Application RPC channel is still not responding'
+      )
+    })
+
+    // Regression: a rejected health check used to close and drop the
+    // replacement, leaving a 'Disconnected' host with no retry loop and no
+    // Reconnect affordance — the failure had to stay recoverable in-app.
+    expect(fresh.closeMock).not.toHaveBeenCalled()
+    expect(harness.hook.client).toBe(fresh)
+    expect(harness.hook.state).toBe('connected')
+
+    harness.unmount()
+  })
+
   it('reports disconnected instead of hanging when the host id is unknown', async () => {
     loadHostsMock.mockResolvedValue([])
 

mobile/src/transport/host-force-reconnect.test.ts

@@ -51,7 +51,7 @@ describe('HostForceReconnectCoordinator', () => {
     await expect(reconnect).resolves.toBeUndefined()
   })
 
-  it('retires a replacement that fails RPC health verification', async () => {
+  it('keeps a replacement that fails RPC health verification', async () => {
     const close = vi.fn()
     const unsubState = vi.fn()
     const client = {
@@ -85,9 +85,11 @@ describe('HostForceReconnectCoordinator', () => {
       })
     ).rejects.toThrow('health failed')
 
-    expect(unsubState).toHaveBeenCalledOnce()
-    expect(close).toHaveBeenCalledOnce()
-    expect(removeEntry).toHaveBeenCalledWith(fresh)
-    expect(current).toBeUndefined()
+    // Regression: retiring the replacement left the host with no client and no
+    // retry loop, so a failed Force Reconnect was unrecoverable in-app.
+    expect(unsubState).not.toHaveBeenCalled()
+    expect(close).not.toHaveBeenCalled()
+    expect(removeEntry).not.toHaveBeenCalledWith(fresh)
+    expect(current).toBe(fresh)
   })
 })

mobile/src/transport/host-force-reconnect.ts

@@ -109,8 +109,10 @@ export class HostForceReconnectCoordinator {
     try {
       await verifyForceReconnectRpcHealth(fresh.client, deadline)
     } catch (error) {
+      // Why: report the unhealthy verdict but keep the replacement — retiring it
+      // strands the host with no client, no retry loop, and a 'Disconnected'
+      // verdict that hides the Reconnect button the user needs to try again.
       if (!this.wasCancelled(operation.hostId, generation)) {
-        this.retireCurrentEntry(operation, fresh)
         throw error
       }
     }