feat(profiles): phase 2 — atomic switch coordinator (#824)

* feat(profiles): ProfileSwitchCoordinator — atomic re-home on profile switch (phase 2)

* fix(ws): deterministic reconnect backoff in tests (testAutoReconnect flake)

* test(ws): harden testAutoReconnect against CI latency (stub token refresh, generous latches)

* test(profiles): remove static Dispatchers mock from coordinator test — it bled into HermesWsClientTest in full-suite runs

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/session/ProfileSwitchCoordinator.kt

@@ -0,0 +1,50 @@
+package com.m57.hermescontrol.data.session
+
+import com.m57.hermescontrol.data.local.AuthManager
+import com.m57.hermescontrol.data.model.SetActiveProfileRequest
+import com.m57.hermescontrol.data.remote.ApiClient
+import com.m57.hermescontrol.data.remote.NetworkResult
+import com.m57.hermescontrol.data.remote.safeApiCall
+import com.m57.hermescontrol.data.ws.HermesWsClient
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.SharedFlow
+import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.withContext
+
+/**
+ * The single flow that performs a profile switch — the mobile equivalent of
+ * desktop's re-home (``requestFreshSession`` + socket swap). Every surface
+ * that switches profiles goes through here, so the switch is atomic instead
+ * of a pile of scattered patches.
+ *
+ * Order matters:
+ *  1. Flip the server's sticky active profile (REST).
+ *  2. Persist the LOCAL selection — the REST interceptor (``?profile=``) and
+ *     the WS params injector (``params.profile``) now scope everything to the
+ *     new profile. The per-server token fallback (phase 1) keeps auth intact:
+ *     no re-login, restart-safe.
+ *  3. Emit [switched] BEFORE the socket re-dial, so chat wipes its stale
+ *     conversation first — when the reconnected socket delivers
+ *     ``gateway.ready``, ``handleGatewayReady`` sees no open session and
+ *     auto-creates a FRESH session in the new profile (desktop parity).
+ *  4. Re-dial the WebSocket so the gateway re-homes chat to the new profile.
+ */
+object ProfileSwitchCoordinator {
+    private val _switched = MutableSharedFlow<String>(extraBufferCapacity = 1)
+    val switched: SharedFlow<String> = _switched.asSharedFlow()
+
+    suspend fun switchProfile(name: String): NetworkResult<Unit> {
+        val result =
+            withContext(Dispatchers.IO) {
+                safeApiCall { ApiClient.hermesApi.setActiveProfile(SetActiveProfileRequest(name)) }
+            }
+        if (result !is NetworkResult.Success) return result
+
+        AuthManager.setSelectedProfileId(name)
+        _switched.emit(name)
+        HermesWsClient.disconnect()
+        HermesWsClient.connect()
+        return result
+    }
+}

app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt

@@ -65,9 +65,21 @@ object HermesWsClient {
 
     // ── Backoff settings ─────────────────────────────────────────────────
 
-    private const val INITIAL_BACKOFF_MS = 1_000L
+    private var initialBackoffMs = 1_000L
     private const val MAX_BACKOFF_MS = 30_000L
     private const val BACKOFF_MULTIPLIER = 2.0
+
+    /**
+     * Test hook: the initial reconnect backoff, overridable so reconnect
+     * tests are deterministic instead of racing real time (CI runners
+     * routinely exceed fixed latch windows). Production keeps 1s.
+     */
+    @VisibleForTesting
+    internal fun setReconnectBackoffForTest(initialMillis: Long) {
+        initialBackoffMs = initialMillis
+        currentBackoff = initialMillis
+    }
+
     private const val MAX_OUTBOUND_MESSAGE_BYTES = 16 * 1024 * 1024
     private const val OUTBOUND_DRAIN_TIMEOUT_MS = 60_000L
 
@@ -89,7 +101,7 @@ object HermesWsClient {
     private var closingSocket: WebSocket? = null
 
     @Volatile
-    private var currentBackoff = INITIAL_BACKOFF_MS
+    private var currentBackoff = initialBackoffMs
 
     private val wsScope = CoroutineScope(Dispatchers.IO + SupervisorJob())
 
@@ -260,7 +272,7 @@ object HermesWsClient {
                 // therefore allowed to leave the terminal AUTH_EXPIRED state.
                 intentionalClose.set(false)
                 _connectionStatus.value = ConnectionStatus.CONNECTING
-                currentBackoff = INITIAL_BACKOFF_MS
+                currentBackoff = initialBackoffMs
                 true
             }
         if (socketToCancel != null) {
@@ -282,7 +294,7 @@ object HermesWsClient {
                 return
             }
             Log.d(TAG, "Default network changed — reconnecting WebSocket")
-            currentBackoff = INITIAL_BACKOFF_MS
+            currentBackoff = initialBackoffMs
             reconnectJob?.cancel()
             reconnectJob = null
             outboundDrainJob?.cancel()
@@ -796,7 +808,7 @@ object HermesWsClient {
                 Log.i(TAG, "WebSocket opened")
                 connected.set(true)
                 _connectionStatus.value = ConnectionStatus.CONNECTED
-                currentBackoff = INITIAL_BACKOFF_MS
+                currentBackoff = initialBackoffMs
                 startHealthTracking()
 
                 while (true) {