diff --git a/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt
index 68780b4d62..7b59dc24f7 100644
--- a/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt
+++ b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt
@@ -839,6 +839,18 @@ fun App(
         relayManager.startMetricsSnapshot(this)
     }
 
+    // Detect host-machine sleep/wake: after a long delay overshoot the OkHttp
+    // sockets we held are dead even though needsToReconnect() still reads false,
+    // so force a hard disconnect+connect. See SleepResumeMonitor.kt.
+    LaunchedEffect(relayManager) {
+        com.vitorpamplona.amethyst.desktop.network.runSleepResumeMonitor {
+            relayManager.client.reconnect(
+                onlyIfChanged = false,
+                ignoreRetryDelays = true,
+            )
+        }
+    }
+
     // Subscriptions coordinator — uses default relay URLs for metadata indexing.
     // Feed subscriptions (inside MainContent) drive actual relay pool connections.
     val subscriptionsCoordinator =
diff --git a/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/network/SleepResumeMonitor.kt b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/network/SleepResumeMonitor.kt
new file mode 100644
index 0000000000..c2d8d3195d
--- /dev/null
+++ b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/network/SleepResumeMonitor.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.desktop.network
+
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+import kotlin.coroutines.coroutineContext
+
+/**
+ * Detects host-machine sleep/wake transitions by watching wall-clock overshoot
+ * of a tight delay loop. When the OS suspends the JVM, [delay] returns far past
+ * its scheduled deadline; the OkHttp websocket connections we held are dead by
+ * then even though [com.vitorpamplona.quartz.nip01Core.relay.client.single.basic.BasicRelayClient]
+ * still reports `isConnected() == true` until the next ping fails — so the
+ * standard keep-alive reconnect path is a no-op and the offline banner stays
+ * stuck until a manual reload.
+ *
+ * Lives here in the desktop app (per Vitor's review of #3221) instead of the
+ * cross-platform NostrClient because sleep/wake semantics differ across
+ * platforms — Android has Doze + network change broadcasts, iOS has app
+ * lifecycle events, and macOS/Linux/Windows desktops can grow real OS-level
+ * sleep hooks here later (NSWorkspace notifications, D-Bus PrepareForSleep,
+ * WM_POWERBROADCAST) without touching Quartz.
+ *
+ * Real OS sleep events would be more precise, but the wall-clock heuristic
+ * needs zero native deps and catches the symptom for v1.
+ */
+suspend fun runSleepResumeMonitor(
+    intervalMs: Long = DEFAULT_INTERVAL_MS,
+    wakeThresholdMs: Long = DEFAULT_WAKE_THRESHOLD_MS,
+    nowMs: () -> Long = { System.currentTimeMillis() },
+    onWake: () -> Unit,
+) {
+    var lastTickMs = nowMs()
+    while (coroutineContext.isActive) {
+        delay(intervalMs)
+        val now = nowMs()
+        val elapsed = now - lastTickMs
+        lastTickMs = now
+        if (elapsed > wakeThresholdMs) onWake()
+    }
+}
+
+private const val DEFAULT_INTERVAL_MS: Long = 60_000L
+
+// 5x the tick — wide enough to ignore GC stalls / brief scheduler hiccups, tight
+// enough to recover quickly after a real sleep.
+private const val DEFAULT_WAKE_THRESHOLD_MS: Long = 5 * DEFAULT_INTERVAL_MS
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/client/NostrClient.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/client/NostrClient.kt
index 092ae94eea..693aa74661 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/client/NostrClient.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/client/NostrClient.kt
@@ -36,7 +36,6 @@ import com.vitorpamplona.quartz.nip01Core.relay.commands.toRelay.Command
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip01Core.relay.sockets.WebsocketBuilder
-import com.vitorpamplona.quartz.utils.TimeUtils
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.FlowPreview
@@ -165,27 +164,12 @@ class NostrClient(
      * error code) would stay disconnected forever in the absence of any
      * subscription change. The per-relay [BasicRelayClient] backoff still
      * gates the actual reconnect attempt, so dead relays are not hammered.
-     *
-     * Also detects system sleep/resume by tracking wall-clock overshoot of the
-     * scheduled tick. If the [delay] returned far later than expected the host
-     * was almost certainly suspended (laptop lid closed, OS sleep), and the
-     * OkHttp websockets we held are dead even though [isConnected] still reads
-     * true until the next ping fails. In that case force a hard reconnect.
      */
     private val keepAliveJob =
         scope.launch {
-            var lastTickMs = TimeUtils.nowMillis()
             while (true) {
                 delay(KEEP_ALIVE_INTERVAL_MS)
-                if (!this@NostrClient.isActive) continue
-                val now = TimeUtils.nowMillis()
-                val elapsed = now - lastTickMs
-                lastTickMs = now
-                if (elapsed > KEEP_ALIVE_WAKE_THRESHOLD_MS) {
-                    // System likely resumed from sleep — force a hard reconnect.
-                    relayPool.disconnect()
-                    relayPool.connect()
-                } else {
+                if (this@NostrClient.isActive) {
                     relayPool.reconnectIfNeedsTo(ignoreRetryDelays = false)
                 }
             }
@@ -193,11 +177,6 @@ class NostrClient(
 
     companion object {
         private const val KEEP_ALIVE_INTERVAL_MS = 60_000L
-
-        // Treat any tick that overshoots the scheduled delay by more than this many
-        // milliseconds as a probable system-sleep resume. 5x interval (5 min) avoids
-        // firing on routine GC stalls or brief OS scheduler pauses.
-        private const val KEEP_ALIVE_WAKE_THRESHOLD_MS = 5 * KEEP_ALIVE_INTERVAL_MS
     }
 
     override fun reconnect(