Push notification dedupe: one message = one notification — an offline message was notified twice (FCM push, then again when the app synced the outbox and mirrored the replayed frames). Fix: the gateway records the highest outbox cursor delivered per device via push (devices.last_pushed_cursor, advanced only on successful send) and returns it in hello.ack; sync-replayed frames carry their outbox cursor in the envelope; the app skips system notifications for replayed frames at/below the watermark (live frames never suppressed — that is the case where no push fired). Also: 5s per-chat push coalescing so a cron delivery (notification frame + message frame) pushes once, and the FCM handler no longer posts a redundant notification (skips when WS is connected or FCM already displayed the notification payload; data-only messages are the exception). Docs: frames.schema.json, 04-wire-protocol.md, 08-push.md §8.8

app/androidApp/src/main/kotlin/dev/iris/app/MainActivity.kt

@@ -15,7 +15,7 @@ import iris.IrisApp
 import iris.platform.AndroidEnv
 import iris.platform.AndroidSecureStore
 import iris.platform.AppBridge
-import iris.platform.NtfyListenerService
+import iris.platform.syncNtfyListener
 
 class MainActivity : ComponentActivity() {
     private val deepLinkChatId = mutableStateOf<String?>(null)
@@ -31,7 +31,9 @@ class MainActivity : ComponentActivity() {
         val store = AndroidSecureStore(applicationContext)
         handleDeepLink(intent)
         requestNotificationPermission()
-        startNtfyListener(store)
+        // M5: the ntfy listener (and its permanent notification) only runs
+        // when the paired gateway pushes via ntfy; unknown ("") = not yet.
+        syncNtfyListener(store.pushBackend)
         setContent {
             val chatId by deepLinkChatId
             val threadId by deepLinkThreadId
@@ -58,10 +60,12 @@ class MainActivity : ComponentActivity() {
      *  extras or an iris://chat/<id>?thread=<tid> URI). */
     private fun handleDeepLink(intent: Intent?) {
         val data = intent?.data
-        val chatId = intent?.getStringExtra("chat_id")
-            ?: data?.pathSegments?.firstOrNull()
-        val threadId = intent?.getStringExtra("thread_id")
-            ?: data?.getQueryParameter("thread")
+        val chatId =
+            intent?.getStringExtra("chat_id")
+                ?: data?.pathSegments?.firstOrNull()
+        val threadId =
+            intent?.getStringExtra("thread_id")
+                ?: data?.getQueryParameter("thread")
         if (!chatId.isNullOrBlank()) {
             deepLinkChatId.value = chatId
             deepLinkThreadId.value = threadId
@@ -77,9 +81,4 @@ class MainActivity : ComponentActivity() {
             }
         }
     }
-
-    private fun startNtfyListener(store: AndroidSecureStore) {
-        if (store.ntfyTopic.isBlank()) return
-        ContextCompat.startForegroundService(this, Intent(this, NtfyListenerService::class.java))
-    }
 }

app/shared/src/androidMain/kotlin/iris/platform/AndroidPush.kt

@@ -1,6 +1,7 @@
 package iris.platform
 
 import android.Manifest
+import android.content.Intent
 import android.content.pm.PackageManager
 import androidx.core.content.ContextCompat
 import iris.state.IrisController
@@ -11,6 +12,19 @@ actual fun setActiveController(controller: Any?) {
     AppBridge.controller = controller as? IrisController
 }
 
+actual fun syncNtfyListener(backend: String) {
+    val context = AndroidEnv.context
+    val intent = Intent(context, NtfyListenerService::class.java)
+    val store = AndroidSecureStore(context)
+    if (backend == "ntfy" && store.ntfyTopic.isNotBlank()) {
+        ContextCompat.startForegroundService(context, intent)
+    } else {
+        // FCM (or unknown) backend: no persistent listener, no permanent
+        // notification. stopService is a no-op when it isn't running.
+        context.stopService(intent)
+    }
+}
+
 actual fun postSystemNotification(
     chatId: String?,
     chatName: String?,

app/shared/src/androidMain/kotlin/iris/platform/AndroidSecureStore.kt

@@ -110,6 +110,10 @@ class AndroidSecureStore(
         get() = prefs.getString(KEY_NTFY_SERVER, "").orEmpty()
         set(value) = prefs.edit().putString(KEY_NTFY_SERVER, value).apply()
 
+    override var pushBackend: String
+        get() = prefs.getString(KEY_PUSH_BACKEND, "").orEmpty()
+        set(value) = prefs.edit().putString(KEY_PUSH_BACKEND, value).apply()
+
     override var threadsEnabled: Boolean
         get() = prefs.getBoolean(KEY_THREADS_ENABLED, false)
         set(value) = prefs.edit().putBoolean(KEY_THREADS_ENABLED, value).apply()
@@ -184,6 +188,7 @@ class AndroidSecureStore(
         const val KEY_FCM_TOKEN = "fcm_token"
         const val KEY_NTFY_TOPIC = "ntfy_topic"
         const val KEY_NTFY_SERVER = "ntfy_server"
+        const val KEY_PUSH_BACKEND = "push_backend"
         const val KEY_THREADS_ENABLED = "threads_enabled"
         const val KEY_TOOL_DETAIL = "tool_detail"
         const val KEY_STREAMING_ENABLED = "streaming_enabled"

app/shared/src/androidMain/kotlin/iris/platform/IrisFirebaseMessagingService.kt

@@ -4,6 +4,7 @@ import android.content.pm.PackageManager
 import androidx.core.content.ContextCompat
 import com.google.firebase.messaging.FirebaseMessagingService
 import com.google.firebase.messaging.RemoteMessage
+import iris.net.GatewayClient
 
 /**
  * M5: FCM handler (docs/08 §8.1).
@@ -30,13 +31,23 @@ class IrisFirebaseMessagingService : FirebaseMessagingService() {
     }
 
     override fun onMessageReceived(message: RemoteMessage) {
+        // Foreground + live WS: the in-app banner already showed this.
+        if (AppBridge.foreground) return
+        // Live WS: the frame arrives over the socket and the controller
+        // mirrors it to a system notification itself — posting here would
+        // duplicate it (docs/08 §8.7).
+        if (AppBridge.controller?.client?.state?.value is GatewayClient.State.Connected) return
+        // Backgrounded/killed: FCM already displayed the `notification`
+        // payload on our behalf (the data payload only carries sync
+        // metadata). Posting again would show a second notification with a
+        // different id. Data-only messages (no notification payload) are the
+        // exception: the app must display them itself.
+        if (message.notification != null) return
         val data = message.data
         val chatId = data["chat_id"] ?: "android:default"
         val threadId = data["thread_id"]
         val title = data["title"] ?: "Iris"
         val body = data["body"] ?: data["title"].orEmpty()
-        // Foreground + live WS: the in-app banner already showed this.
-        if (AppBridge.foreground) return
         if (ContextCompat.checkSelfPermission(applicationContext, android.Manifest.permission.POST_NOTIFICATIONS)
             != PackageManager.PERMISSION_GRANTED
         ) {

app/shared/src/commonMain/kotlin/iris/data/SecureStore.kt

@@ -30,6 +30,11 @@ interface SecureStore {
     /** ntfy server URL (M5; from hello.ack server_caps; default ntfy.sh). */
     var ntfyServer: String
 
+    /** Push backend of the paired gateway ("fcm"/"ntfy"; from hello.ack
+     *  server_caps; empty when unknown — decides whether the ntfy listener
+     *  foreground service runs at all). */
+    var pushBackend: String
+
     /** UI setting: show threads (topics) in the chat view. */
     var threadsEnabled: Boolean
 
@@ -61,6 +66,10 @@ interface SecureStore {
      *  system font scale). */
     var fontSizeScale: Float
 
-    fun savePairing(url: String, token: String)
+    fun savePairing(
+        url: String,
+        token: String,
+    )
+
     fun clear()
 }

app/shared/src/commonMain/kotlin/iris/net/GatewayClient.kt

@@ -70,7 +70,14 @@ class GatewayClient(
     sealed interface State {
         data object Disconnected : State
         data object Connecting : State
-        data class Connected(val caps: ServerCaps, val channels: List<ChannelInfo>) : State
+        data class Connected(
+            val caps: ServerCaps,
+            val channels: List<ChannelInfo>,
+            /** M5: highest outbox cursor already pushed to this device
+             *  (from hello.ack; 0 = never). Sync-replayed frames at/below
+             *  it must not re-post system notifications (docs/08 §8.7). */
+            val lastPushedCursor: Long = 0,
+        ) : State
         data object Reconnecting : State
         data class AuthFailed(val message: String) : State
     }
@@ -275,7 +282,7 @@ class GatewayClient(
         helloAck.invokeOnCompletion { e ->
             if (e == null) {
                 val ack = helloAck.getCompleted()
-                _state.value = State.Connected(ack.serverCaps, ack.channels)
+                _state.value = State.Connected(ack.serverCaps, ack.channels, ack.lastPushedCursor)
                 // M5: reconnect catch-up — replay frames parked while offline.
                 val local = store.syncCursor
                 if (local < ack.syncCursor) {

app/shared/src/commonMain/kotlin/iris/platform/PlatformPush.kt

@@ -29,3 +29,12 @@ expect fun postSystemNotification(
  * FCM / ntfy services can reach it). No-op on desktop.
  */
 expect fun setActiveController(controller: Any?)
+
+/**
+ * Align the ntfy listener with the paired gateway's push backend (Android:
+ * start/stop the listener foreground service — and with it the permanent
+ * "Listening for messages" notification; no-op on desktop). The listener
+ * only runs when the gateway actually pushes via ntfy; FCM gateways need
+ * no persistent listener.
+ */
+expect fun syncNtfyListener(backend: String)

app/shared/src/commonMain/kotlin/iris/protocol/Protocol.kt

@@ -115,6 +115,11 @@ data class Frame(
     val type: String,
     @SerialName("chat_id") val chatId: String? = null,
     @SerialName("thread_id") val threadId: String? = null,
+    /** Outbox cursor this frame was parked under. Set only on frames
+     *  replayed by `sync` (live frames carry none) — the app skips
+     *  re-notifying replayed frames with `cursor <= lastPushedCursor`
+     *  (they already woke the device via push, docs/08 §8.7). */
+    val cursor: Long? = null,
     val payload: JsonElement = JsonObject(emptyMap()),
 ) {
     /** Payload as a JSON object (the wire format); parse per-type with
@@ -185,6 +190,10 @@ data class HelloAckPayload(
     @SerialName("server_caps") val serverCaps: ServerCaps = ServerCaps(),
     @SerialName("sync_cursor") val syncCursor: Long = 0,
     val channels: List<ChannelInfo> = emptyList(),
+    /** M5: highest outbox cursor already delivered to THIS device via the
+     *  push backend (0 = never). Sync-replayed frames at/below it must not
+     *  re-post system notifications (dedupe, docs/08 §8.7). */
+    @SerialName("last_pushed_cursor") val lastPushedCursor: Long = 0,
 )
 
 // ── message (server -> app) ─────────────────────────────────────────────

app/shared/src/commonMain/kotlin/iris/state/IrisController.kt

@@ -13,6 +13,7 @@ import iris.platform.PickedFile
 import iris.platform.isAppForeground
 import iris.platform.mediaCacheBaseDir
 import iris.platform.postSystemNotification
+import iris.platform.syncNtfyListener
 import iris.protocol.ChannelDeletedPayload
 import iris.protocol.ChannelInfo
 import iris.protocol.CommandsCatalogPayload
@@ -135,6 +136,19 @@ class IrisController(
     private val _gatewayStatus = MutableStateFlow<String?>(null)
     val gatewayStatus: StateFlow<String?> = _gatewayStatus.asStateFlow()
 
+    /** M5: highest outbox cursor already delivered to this device via the
+     *  push backend (from hello.ack; 0 = never). Sync-replayed frames with
+     *  `cursor <= lastPushedCursor` already woke the device via push, so the
+     *  app must not post a second system notification for them (docs/08
+     *  §8.7). In-memory: hello.ack refreshes it on every (re)connect. */
+    @Volatile
+    private var lastPushedCursor: Long = 0
+
+    /** True while [frame] is a sync replay that already reached the device
+     *  via push (live frames carry no cursor and are never suppressed). */
+    private fun isPushedReplay(frame: iris.protocol.Frame): Boolean =
+        frame.cursor?.let { it <= lastPushedCursor } ?: false
+
     // ── M3: threads toggle (per-app for now; per-channel lands later) ─────
     // Persisted (Settings → "Threads").
     private val _threadsEnabled = MutableStateFlow(store.threadsEnabled)
@@ -392,13 +406,15 @@ class IrisController(
                         when (frame.type) {
                             TYPE_MESSAGE_STOP -> {
                                 frame.payloadAs<MessageStopPayload>()?.let {
-                                    notifyMessageIfBackgrounded(frame.chatId, frame.threadId, it.finalText)
+                                    if (!isPushedReplay(frame)) {
+                                        notifyMessageIfBackgrounded(frame.chatId, frame.threadId, it.finalText)
+                                    }
                                 }
                             }
 
                             TYPE_MESSAGE -> {
                                 frame.payloadAs<MessagePayload>()?.let {
-                                    if (it.role == ROLE_ASSISTANT) {
+                                    if (it.role == ROLE_ASSISTANT && !isPushedReplay(frame)) {
                                         notifyMessageIfBackgrounded(frame.chatId, frame.threadId, it.text)
                                     }
                                 }
@@ -492,8 +508,10 @@ class IrisController(
                             // M5: WS is live but the app is backgrounded — the
                             // in-app banner is invisible, so mirror to a system
                             // notification (the push backend only fires when
-                            // there is no live subscriber).
-                            if (!isAppForeground()) {
+                            // there is no live subscriber). Suppressed for
+                            // sync replays that already woke the device via
+                            // push (docs/08 §8.7).
+                            if (!isAppForeground() && !isPushedReplay(frame)) {
                                 postSystemNotification(p.chatId, null, p.title, p.body, p.threadId)
                             }
                         }
@@ -539,6 +557,8 @@ class IrisController(
                 prevState = s
                 if (s is GatewayClient.State.Connected) {
                     channels.setAll(s.channels)
+                    // M5: refresh the push-dedupe watermark (docs/08 §8.7).
+                    lastPushedCursor = s.lastPushedCursor
                     val home = s.channels.firstOrNull { it.isDefault }?.chatId
                     if (home != null) {
                         _homeChannel.value = home
@@ -554,6 +574,11 @@ class IrisController(
                     if (s.caps.pushNtfyServer.isNotBlank()) {
                         store.ntfyServer = s.caps.pushNtfyServer
                     }
+                    // M5: align the ntfy listener (and its permanent
+                    // "Listening for messages" notification) with the
+                    // gateway's push backend — only ntfy gateways need it.
+                    store.pushBackend = s.caps.push
+                    syncNtfyListener(s.caps.push)
                     // M5: a deep link tapped before we were connected.
                     applyDeepLink()
                     // Slash-command catalog for the composer's "/" drawer

app/shared/src/desktopMain/kotlin/iris/platform/DesktopPush.kt

@@ -19,6 +19,10 @@ actual fun setActiveController(controller: Any?) {
     DesktopBridge.controller = controller as? IrisController
 }
 
+actual fun syncNtfyListener(backend: String) {
+    // Desktop has no ntfy listener service.
+}
+
 /**
  * M6: OS notifications (docs/11 §11.2). Desktop has no FCM; the tray + the
  * platform notifier cover the "backgrounded" leg. Shells out to
@@ -26,34 +30,45 @@ actual fun setActiveController(controller: Any?) {
  * Best effort — failures are ignored (the in-app banner is the primary path).
  */
 object DesktopNotifier {
-    fun post(title: String, body: String) {
+    fun post(
+        title: String,
+        body: String,
+    ) {
         try {
             val os = System.getProperty("os.name").lowercase()
-            val cmd = when {
-                os.contains("linux") ->
-                    listOf("notify-send", "-a", "Iris", "-c", "iris", title, body)
-                os.contains("mac") ->
-                    listOf(
-                        "osascript", "-e",
-                        "display notification \"${esc(body)}\" with title \"${esc(title)}\"",
-                    )
-                else ->
-                    listOf(
-                        "powershell", "-NoProfile", "-Command",
-                        "Add-Type -AssemblyName System.Windows.Forms; " +
-                            "\$n = New-Object System.Windows.Forms.NotifyIcon; " +
-                            "\$n.Icon = [System.Drawing.SystemIcons]::Information; " +
-                            "\$n.Visible = \$true; " +
-                            "\$n.ShowBalloonTip(4000, \"${esc(title)}\", \"${esc(body)}\", " +
-                            "[System.Windows.Forms.ToolTipIcon]::Info); " +
-                            "Start-Sleep -Milliseconds 4500; \$n.Dispose()",
-                    )
-            }
+            val cmd =
+                when {
+                    os.contains("linux") -> {
+                        listOf("notify-send", "-a", "Iris", "-c", "iris", title, body)
+                    }
+
+                    os.contains("mac") -> {
+                        listOf(
+                            "osascript",
+                            "-e",
+                            "display notification \"${esc(body)}\" with title \"${esc(title)}\"",
+                        )
+                    }
+
+                    else -> {
+                        listOf(
+                            "powershell",
+                            "-NoProfile",
+                            "-Command",
+                            "Add-Type -AssemblyName System.Windows.Forms; " +
+                                "\$n = New-Object System.Windows.Forms.NotifyIcon; " +
+                                "\$n.Icon = [System.Drawing.SystemIcons]::Information; " +
+                                "\$n.Visible = \$true; " +
+                                "\$n.ShowBalloonTip(4000, \"${esc(title)}\", \"${esc(body)}\", " +
+                                "[System.Windows.Forms.ToolTipIcon]::Info); " +
+                                "Start-Sleep -Milliseconds 4500; \$n.Dispose()",
+                        )
+                    }
+                }
             ProcessBuilder(cmd).redirectErrorStream(true).start()
         } catch (_: Exception) {
         }
     }
 
-    private fun esc(s: String): String =
-        s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", " ")
+    private fun esc(s: String): String = s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", " ")
 }

app/shared/src/desktopMain/kotlin/iris/platform/DesktopSecureStore.kt

@@ -37,6 +37,7 @@ class DesktopSecureStore : SecureStore {
         val fcmToken: String = "",
         val ntfyTopic: String = "",
         val ntfyServer: String = "",
+        val pushBackend: String = "",
         val threadsEnabled: Boolean = false,
         val toolDetail: String = "truncated",
         val streamingEnabled: Boolean = true,
@@ -153,6 +154,13 @@ class DesktopSecureStore : SecureStore {
             save(d.copy(ntfyServer = value))
         }
 
+    override var pushBackend: String
+        get() = load().pushBackend
+        set(value) {
+            val d = load()
+            save(d.copy(pushBackend = value))
+        }
+
     override var threadsEnabled: Boolean
         get() = load().threadsEnabled
         set(value) {

docs/04-wire-protocol.md

@@ -21,6 +21,10 @@ Every frame:
 - `v` — protocol version (currently `1`). Server rejects unknown major versions.
 - `id` — request id (client-chosen). Responses/acks echo it. Events have no `id`.
 - `chat_id` / `thread_id` — top-level for convenience; may also be in `payload`.
+- `cursor` — outbox cursor the frame was parked under. Present **only** on
+  frames replayed by `sync` (live frames carry none). The app compares it
+  against `last_pushed_cursor` from `hello.ack` to skip re-notifying frames
+  that already woke the device via push (`08-push.md` §8.7).
 - Unknown `type`s are ignored (forward-compat); unknown `payload` fields ignored.
 
 **Binary media frames** are not JSON. A media transfer is: one JSON header frame
@@ -36,9 +40,14 @@ Pairing succeeded.
   "server_caps":{"streaming":true,"reasoning":true,"tools":true,"media":true,
                  "search":true,"push":"fcm","pickers":true},
   "sync_cursor":1042,
+  "last_pushed_cursor":1040,
   "channels":[{"chat_id":"android:default","name":"Default","kind":"default","is_default":true}]
 }}
 ```
+`last_pushed_cursor` is the highest outbox cursor already delivered to THIS
+device via the push backend (0 = never). The app skips system notifications
+for sync-replayed frames with `cursor <= last_pushed_cursor` — they already
+woke the device via push (dedupe, `08-push.md` §8.7).
 
 ### `message`
 A final / standalone message.

docs/08-push.md

@@ -103,3 +103,33 @@ persist until acted on.
   over the authenticated WS.
 - ntfy: use a **private topic + auth token** for any real trust boundary (hermes
   ntfy adapter guidance).
+
+## 8.8 Notification dedupe (push vs. sync)
+
+A message sent while the device is offline is notified **twice** by naive
+design: once by the push (FCM displays the `notification` payload), and again
+when the app reconnects, syncs the outbox, and mirrors the replayed frames to
+system notifications (the background-mirror path, §8.5). The fix is a per-
+device push watermark:
+
+- **Gateway** records the highest outbox cursor delivered to each device via
+  the push backend (`devices.last_pushed_cursor`, advanced only on a
+  *successful* send) and returns it in `hello.ack` as `last_pushed_cursor`.
+- **Gateway** coalesces back-to-back pushes per chat (5 s window): a cron
+  delivery parks a notification frame AND a message frame, and only the first
+  pushes — the second reaches the app via sync (tap the first notification).
+- **Gateway** tags every `sync`-replayed frame with its outbox cursor in the
+  frame envelope (`cursor`; live frames carry none).
+- **App** skips system notifications for replayed frames with
+  `cursor <= lastPushedCursor` (they already woke the device). Live frames are
+  never suppressed — that is exactly the case where no push fired and the app
+  must notify itself.
+- **App** FCM handler (`onMessageReceived`) posts nothing when the WS is
+  connected (the background-mirror path handles it) and nothing when the
+  message carried a `notification` payload (FCM already displayed it);
+  data-only messages are the exception (the app must display them itself).
+
+Residual edge: FCM is at-least-once, so a lost device ack can still produce a
+duplicate *system-displayed* notification (two `FCM-Notification:*` ids). The
+designed evolution is the data-only push option (§8.2.1), which moves display
+into the app and lets it use a stable per-message notification id.

docs/protocol/frames.schema.json

@@ -12,6 +12,7 @@
       "type": { "type": "string", "description": "Frame type (see frame_types)." },
       "chat_id": { "type": "string", "description": "Optional chat scope (e.g. android:default, android:chan_7)." },
       "thread_id": { "type": "string", "description": "Optional thread scope within a chat_id." },
+      "cursor": { "type": "integer", "description": "Outbox cursor the frame was parked under. Present ONLY on frames replayed by sync (live frames carry none). The app skips re-notifying replayed frames with cursor <= last_pushed_cursor (docs/08 §8.7)." },
       "payload": { "type": "object", "description": "Type-specific payload." }
     }
   },
@@ -22,6 +23,7 @@
         "payload": {
           "server_caps": { "type": "object", "properties": { "streaming": {"type":"boolean"}, "reasoning": {"type":"boolean"}, "tools": {"type":"boolean"}, "media": {"type":"boolean"}, "search": {"type":"boolean"}, "push": {"type":"string","enum":["fcm","ntfy","none"]}, "push_ntfy_server": {"type":"string","description":"ntfy server URL for the app's listener; empty string when the backend is not ntfy."}, "pickers": {"type":"boolean"} } },
           "sync_cursor": { "type": "integer" },
+          "last_pushed_cursor": { "type": "integer", "description": "Highest outbox cursor already delivered to THIS device via the push backend (0 = never). The app skips system notifications for sync-replayed frames at/below it (dedupe, docs/08 §8.7)." },
           "channels": { "type": "array", "items": { "$ref": "#/definitions/channel" } }
         }
       },

gateway-plugin/adapter.py

@@ -439,6 +439,11 @@ def _strip_streaming_cursor(text: str) -> str:
     return text
 
 
+# M5: coalesce back-to-back pushes for the same chat (a cron delivery parks
+# a notification frame AND a message frame; only the first should push).
+_PUSH_COALESCE_S = 5.0
+
+
 def _push_preview(text: Any, limit: int = 120) -> str:
     """Short single-line preview for push bodies (lock-screen privacy: no
     secrets, no full bodies -- full content arrives via ``sync``)."""
@@ -1019,6 +1024,9 @@ class AndroidAdapter(BasePlatformAdapter):
             ntfy_auth_token=_get_scoped_secret("NTFY_AUTH_TOKEN"),
         )
         self._prune_notified_at = 0.0
+        # M5: per-chat push throttle (epoch seconds of the last successful
+        # push). The coalesced frame still reaches the app via sync.
+        self._last_push_at: Dict[str, float] = {}
 
     def _turn_state(self, chat_id: str) -> _TurnState:
         st = self._turns.get(chat_id)
@@ -1537,6 +1545,16 @@ class AndroidAdapter(BasePlatformAdapter):
         summary = self._push_summary(frame)
         if summary is None:
             return
+        # M5: coalesce back-to-back pushes for the same chat (cron delivery
+        # = notification frame + message frame). The suppressed frame is
+        # still synced when the app reconnects.
+        now = time.time()
+        if now - self._last_push_at.get(chat_id, 0.0) < _PUSH_COALESCE_S:
+            logger.info(
+                "android: push coalesced for %s (%s frame within %.0fs of last push)",
+                chat_id, frame.type, _PUSH_COALESCE_S,
+            )
+            return
         title, body, kind, priority = summary
         backend = self._push
         if backend is None or not backend.token_field:
@@ -1578,6 +1596,15 @@ class AndroidAdapter(BasePlatformAdapter):
                 logger.warning("android: push via %s failed", backend.name, exc_info=True)
                 continue
             if ok:
+                # M5: remember that this cursor reached the device via push,
+                # so the app can dedupe it on the next sync replay.
+                try:
+                    self._devices.update_push_cursor(device_id, cursor)
+                except Exception:
+                    logger.warning(
+                        "android: push cursor update failed for %s", device_id, exc_info=True
+                    )
+                self._last_push_at[chat_id] = time.time()
                 logger.info(
                     "android: push via %s -> %s (%s, chat=%s)",
                     backend.name, device_id, frame.type, chat_id,
@@ -2362,6 +2389,10 @@ class AndroidAdapter(BasePlatformAdapter):
                 id=raw.get("id") if isinstance(raw.get("id"), int) else None,
                 chat_id=raw.get("chat_id") if isinstance(raw.get("chat_id"), str) else e.get("chat_id"),
                 thread_id=raw.get("thread_id") if isinstance(raw.get("thread_id"), str) else None,
+                # M5: tag replayed frames with their outbox cursor so the app
+                # can skip re-notifying frames that already woke the device
+                # via push (cursor <= last_pushed_cursor, docs/08 §8.7).
+                cursor=e.get("cursor"),
                 v=raw.get("v") if isinstance(raw.get("v"), int) else protocol.PROTOCOL_VERSION,
             )
             await self._ws_server.send_to(device_id, replayed)

gateway-plugin/pairing.py

@@ -17,7 +17,7 @@ import sqlite3
 import threading
 import time
 from pathlib import Path
-from typing import Any, Dict, List, Optional
+from typing import Any
 from urllib.parse import quote
 
 logger = logging.getLogger(__name__)
@@ -31,7 +31,7 @@ def generate_token() -> str:
     return secrets.token_hex(TOKEN_BYTES)
 
 
-def verify_token(provided: Optional[str], expected: Optional[str]) -> bool:
+def verify_token(provided: str | None, expected: str | None) -> bool:
     """Constant-time token comparison (never time-leaks the token)."""
     if not provided or not expected:
         return False
@@ -65,6 +65,7 @@ def pairing_url(host: str, port: int, secure: bool = False) -> str:
 # Device registry (SQLite)
 # ---------------------------------------------------------------------------
 
+
 class DeviceRegistry:
     """Persistent device registry under ``get_hermes_home()/"android"``.
 
@@ -88,20 +89,32 @@ class DeviceRegistry:
                     caps       TEXT NOT NULL DEFAULT '{}',
                     fcm_token  TEXT,
                     ntfy_topic TEXT,
+                    last_pushed_cursor INTEGER NOT NULL DEFAULT 0,
                     last_seen  REAL NOT NULL DEFAULT 0,
                     created    REAL NOT NULL DEFAULT 0
                 )
                 """
             )
+            # M5: migrate pre-push-cursor databases (the column carries the
+            # highest outbox cursor already delivered to the device via the
+            # push backend; hello.ack returns it for notification dedupe).
+            cols = {
+                r["name"]
+                for r in self._conn.execute("PRAGMA table_info(devices)").fetchall()
+            }
+            if "last_pushed_cursor" not in cols:
+                self._conn.execute(
+                    "ALTER TABLE devices ADD COLUMN last_pushed_cursor INTEGER NOT NULL DEFAULT 0"
+                )
             self._conn.commit()
 
     def upsert(
         self,
         device_id: str,
         name: str,
-        caps: Optional[Dict[str, Any]] = None,
-        fcm_token: Optional[str] = None,
-        ntfy_topic: Optional[str] = None,
+        caps: dict[str, Any] | None = None,
+        fcm_token: str | None = None,
+        ntfy_topic: str | None = None,
     ) -> None:
         now = time.time()
         caps_json = json.dumps(caps or {}, separators=(",", ":"))
@@ -125,8 +138,8 @@ class DeviceRegistry:
     def update_push_tokens(
         self,
         device_id: str,
-        fcm_token: Optional[str] = None,
-        ntfy_topic: Optional[str] = None,
+        fcm_token: str | None = None,
+        ntfy_topic: str | None = None,
     ) -> None:
         with self._lock:
             self._conn.execute(
@@ -149,14 +162,43 @@ class DeviceRegistry:
             )
             self._conn.commit()
 
-    def get(self, device_id: str) -> Optional[Dict[str, Any]]:
+    def update_push_cursor(self, device_id: str, cursor: int) -> None:
+        """Advance the device's last-pushed cursor (monotonic; never
+        regresses). Called after a successful push send."""
+        try:
+            cursor = max(0, int(cursor or 0))
+        except (TypeError, ValueError):
+            return
+        with self._lock:
+            self._conn.execute(
+                """
+                UPDATE devices SET last_pushed_cursor = MAX(last_pushed_cursor, ?)
+                WHERE device_id = ?
+                """,
+                (cursor, device_id),
+            )
+            self._conn.commit()
+
+    def last_pushed_cursor(self, device_id: str) -> int:
+        """Highest outbox cursor pushed to this device (0 = never/unknown)."""
+        with self._lock:
+            row = self._conn.execute(
+                "SELECT last_pushed_cursor FROM devices WHERE device_id = ?",
+                (device_id,),
+            ).fetchone()
+        try:
+            return int(row["last_pushed_cursor"]) if row else 0
+        except (TypeError, ValueError, KeyError, IndexError):
+            return 0
+
+    def get(self, device_id: str) -> dict[str, Any] | None:
         with self._lock:
             row = self._conn.execute(
                 "SELECT * FROM devices WHERE device_id = ?", (device_id,)
             ).fetchone()
         return _row_to_device(row) if row else None
 
-    def list(self) -> List[Dict[str, Any]]:
+    def list(self) -> list[dict[str, Any]]:
         with self._lock:
             rows = self._conn.execute(
                 "SELECT * FROM devices ORDER BY last_seen DESC"
@@ -171,7 +213,7 @@ class DeviceRegistry:
                 pass
 
 
-def _row_to_device(row: sqlite3.Row) -> Dict[str, Any]:
+def _row_to_device(row: sqlite3.Row) -> dict[str, Any]:
     try:
         caps = json.loads(row["caps"] or "{}")
         if not isinstance(caps, dict):
@@ -184,6 +226,7 @@ def _row_to_device(row: sqlite3.Row) -> Dict[str, Any]:
         "caps": caps,
         "fcm_token": row["fcm_token"],
         "ntfy_topic": row["ntfy_topic"],
+        "last_pushed_cursor": row["last_pushed_cursor"] or 0,
         "last_seen": row["last_seen"],
         "created": row["created"],
     }

gateway-plugin/protocol.py

@@ -17,7 +17,7 @@ Milestone M5: notification, fcm.register, read.receipt, status.
 
 import json
 from dataclasses import dataclass, field
-from typing import Any, Dict, List, Optional
+from typing import Any, Optional
 
 PROTOCOL_VERSION = 1
 
@@ -146,30 +146,38 @@ STATUS_DEGRADED = "degraded"
 # Envelope
 # ---------------------------------------------------------------------------
 
+
 @dataclass
 class Frame:
     """One wire frame.
 
-    ``v`` is always serialised; ``id``/``chat_id``/``thread_id`` are
-    omitted when ``None`` (events carry no ``id``; chat-scoped frames carry
-    ``chat_id``/``thread_id`` at the top level for convenience).
+    ``v`` is always serialised; ``id``/``chat_id``/``thread_id``/``cursor``
+    are omitted when ``None`` (events carry no ``id``; chat-scoped frames
+    carry ``chat_id``/``thread_id`` at the top level for convenience).
+
+    ``cursor`` is set only on frames replayed by ``sync``: the outbox cursor
+    the frame was parked under. The app uses it to skip re-notifying frames
+    that already woke the device via push (docs/08 §8.7).
     """
 
     type: str
-    payload: Dict[str, Any] = field(default_factory=dict)
-    id: Optional[int] = None
-    chat_id: Optional[str] = None
-    thread_id: Optional[str] = None
+    payload: dict[str, Any] = field(default_factory=dict)
+    id: int | None = None
+    chat_id: str | None = None
+    thread_id: str | None = None
+    cursor: int | None = None
     v: int = PROTOCOL_VERSION
 
-    def to_dict(self) -> Dict[str, Any]:
-        d: Dict[str, Any] = {"v": self.v, "type": self.type}
+    def to_dict(self) -> dict[str, Any]:
+        d: dict[str, Any] = {"v": self.v, "type": self.type}
         if self.id is not None:
             d["id"] = self.id
         if self.chat_id is not None:
             d["chat_id"] = self.chat_id
         if self.thread_id is not None:
             d["thread_id"] = self.thread_id
+        if self.cursor is not None:
+            d["cursor"] = self.cursor
         d["payload"] = self.payload
         return d
 
@@ -202,17 +210,29 @@ class Frame:
         thread_id = data.get("thread_id")
         if not isinstance(thread_id, str):
             thread_id = None
-        return cls(type=ftype, payload=payload, id=fid, chat_id=chat_id, thread_id=thread_id)
+        cursor = data.get("cursor")
+        if not isinstance(cursor, int) or isinstance(cursor, bool):
+            cursor = None
+        return cls(
+            type=ftype,
+            payload=payload,
+            id=fid,
+            chat_id=chat_id,
+            thread_id=thread_id,
+            cursor=cursor,
+        )
 
 
 # ---------------------------------------------------------------------------
 # Frame constructors (server -> app)
 # ---------------------------------------------------------------------------
 
+
 def hello_ack(
-    server_caps: Dict[str, Any],
+    server_caps: dict[str, Any],
     sync_cursor: int = 0,
-    channels: Optional[list] = None,
+    channels: list | None = None,
+    last_pushed_cursor: int = 0,
 ) -> Frame:
     return Frame(
         type=TYPE_HELLO_ACK,
@@ -220,6 +240,11 @@ def hello_ack(
             "server_caps": server_caps,
             "sync_cursor": sync_cursor,
             "channels": channels or [],
+            # M5: highest outbox cursor already delivered to THIS device via
+            # the push backend (0 = never). The app skips system
+            # notifications for sync-replayed frames at/below it (dedupe,
+            # docs/08 §8.7).
+            "last_pushed_cursor": last_pushed_cursor,
         },
     )
 
@@ -230,15 +255,15 @@ def message(
     role: str,
     text: str,
     *,
-    thread_id: Optional[str] = None,
-    reasoning: Optional[str] = None,
-    media: Optional[list] = None,
-    reply_to: Optional[str] = None,
-    model: Optional[str] = None,
-    tokens: Optional[int] = None,
-    ts: Optional[int] = None,
+    thread_id: str | None = None,
+    reasoning: str | None = None,
+    media: list | None = None,
+    reply_to: str | None = None,
+    model: str | None = None,
+    tokens: int | None = None,
+    ts: int | None = None,
 ) -> Frame:
-    payload: Dict[str, Any] = {
+    payload: dict[str, Any] = {
         "message_id": message_id,
         "role": role,
         "text": text,
@@ -255,10 +280,12 @@ def message(
         payload["tokens"] = tokens
     if ts is not None:
         payload["ts"] = ts
-    return Frame(type=TYPE_MESSAGE, chat_id=chat_id, thread_id=thread_id, payload=payload)
+    return Frame(
+        type=TYPE_MESSAGE, chat_id=chat_id, thread_id=thread_id, payload=payload
+    )
 
 
-def typing(chat_id: str, on: bool = True, *, thread_id: Optional[str] = None) -> Frame:
+def typing(chat_id: str, on: bool = True, *, thread_id: str | None = None) -> Frame:
     return Frame(
         type=TYPE_TYPING,
         chat_id=chat_id,
@@ -271,12 +298,13 @@ def typing(chat_id: str, on: bool = True, *, thread_id: Optional[str] = None) ->
 # Streaming frames (M2)
 # ---------------------------------------------------------------------------
 
+
 def message_start(
     chat_id: str,
     message_id: str,
     role: str = ROLE_ASSISTANT,
     *,
-    thread_id: Optional[str] = None,
+    thread_id: str | None = None,
 ) -> Frame:
     """Open a streaming bubble."""
     return Frame(
@@ -292,7 +320,7 @@ def message_update(
     message_id: str,
     text: str,
     *,
-    thread_id: Optional[str] = None,
+    thread_id: str | None = None,
 ) -> Frame:
     """Replace the live bubble text (full snapshot)."""
     return Frame(
@@ -308,14 +336,14 @@ def message_stop(
     message_id: str,
     final_text: str,
     *,
-    thread_id: Optional[str] = None,
-    reasoning: Optional[str] = None,
-    model: Optional[str] = None,
-    tokens: Optional[int] = None,
-    ts: Optional[int] = None,
+    thread_id: str | None = None,
+    reasoning: str | None = None,
+    model: str | None = None,
+    tokens: int | None = None,
+    ts: int | None = None,
 ) -> Frame:
     """Finalize a streaming bubble."""
-    payload: Dict[str, Any] = {
+    payload: dict[str, Any] = {
         "message_id": message_id,
         "final_text": final_text,
     }
@@ -339,16 +367,17 @@ def message_stop(
 # Tool activity frames (M2)
 # ---------------------------------------------------------------------------
 
+
 def tool_start(
     chat_id: str,
     index: int,
     name: str,
     *,
-    thread_id: Optional[str] = None,
-    preview: Optional[str] = None,
-    args: Optional[Dict[str, Any]] = None,
+    thread_id: str | None = None,
+    preview: str | None = None,
+    args: dict[str, Any] | None = None,
 ) -> Frame:
-    payload: Dict[str, Any] = {"index": index, "name": name}
+    payload: dict[str, Any] = {"index": index, "name": name}
     if preview:
         payload["preview"] = preview
     if args:
@@ -366,10 +395,10 @@ def tool_progress(
     index: int,
     name: str,
     *,
-    thread_id: Optional[str] = None,
-    note: Optional[str] = None,
+    thread_id: str | None = None,
+    note: str | None = None,
 ) -> Frame:
-    payload: Dict[str, Any] = {"index": index, "name": name}
+    payload: dict[str, Any] = {"index": index, "name": name}
     if note:
         payload["note"] = note
     return Frame(
@@ -385,12 +414,12 @@ def tool_end(
     index: int,
     name: str,
     *,
-    thread_id: Optional[str] = None,
+    thread_id: str | None = None,
     ok: bool = True,
-    duration: Optional[float] = None,
-    output_preview: Optional[str] = None,
+    duration: float | None = None,
+    output_preview: str | None = None,
 ) -> Frame:
-    payload: Dict[str, Any] = {"index": index, "name": name, "ok": ok}
+    payload: dict[str, Any] = {"index": index, "name": name, "ok": ok}
     if duration is not None:
         payload["duration"] = duration
     if output_preview:
@@ -407,12 +436,13 @@ def tool_end(
 # Commentary frame (M2)
 # ---------------------------------------------------------------------------
 
+
 def commentary(
     chat_id: str,
     message_id: str,
     text: str,
     *,
-    thread_id: Optional[str] = None,
+    thread_id: str | None = None,
 ) -> Frame:
     """An intermediate assistant beat (between tool iterations)."""
     return Frame(
@@ -427,9 +457,10 @@ def commentary(
 # Channel directory frames (M3)
 # ---------------------------------------------------------------------------
 
-def _channel_payload(entry: Dict[str, Any]) -> Dict[str, Any]:
+
+def _channel_payload(entry: dict[str, Any]) -> dict[str, Any]:
     """Project a directory entry onto the wire shape."""
-    payload: Dict[str, Any] = {
+    payload: dict[str, Any] = {
         "chat_id": entry.get("chat_id"),
         "name": entry.get("name"),
         "kind": entry.get("kind", "channel"),
@@ -451,7 +482,7 @@ def _channel_payload(entry: Dict[str, Any]) -> Dict[str, Any]:
     return payload
 
 
-def channel_created(entry: Dict[str, Any], auto: bool = False) -> Frame:
+def channel_created(entry: dict[str, Any], auto: bool = False) -> Frame:
     """Broadcast: a channel/thread was created.
 
     ``auto=True`` marks a thread the gateway minted itself for an incoming
@@ -465,7 +496,7 @@ def channel_created(entry: Dict[str, Any], auto: bool = False) -> Frame:
     return Frame(type=TYPE_CHANNEL_CREATED, payload=payload)
 
 
-def channel_renamed(entry: Dict[str, Any]) -> Frame:
+def channel_renamed(entry: dict[str, Any]) -> Frame:
     """Broadcast: a channel/thread was renamed."""
     return Frame(type=TYPE_CHANNEL_RENAMED, payload=_channel_payload(entry))
 
@@ -475,7 +506,7 @@ def channel_deleted(chat_id: str) -> Frame:
     return Frame(type=TYPE_CHANNEL_DELETED, payload={"chat_id": chat_id})
 
 
-def channel_list(channels: List[Dict[str, Any]]) -> Frame:
+def channel_list(channels: list[dict[str, Any]]) -> Frame:
     """Full directory (response to a ``channel.list`` request)."""
     return Frame(
         type=TYPE_CHANNEL_LIST,
@@ -487,12 +518,13 @@ def channel_list(channels: List[Dict[str, Any]]) -> Frame:
 # Search frames (M3)
 # ---------------------------------------------------------------------------
 
+
 def search_results(
     query: str,
     scope: str,
-    hits: List[Dict[str, Any]],
+    hits: list[dict[str, Any]],
     *,
-    id: Optional[int] = None,
+    id: int | None = None,
 ) -> Frame:
     """Response to a ``search`` request.
 
@@ -509,7 +541,8 @@ def search_results(
 # Slash-command catalog frames
 # ---------------------------------------------------------------------------
 
-def commands_catalog(commands: List[Dict[str, Any]], *, id: Optional[int] = None) -> Frame:
+
+def commands_catalog(commands: list[dict[str, Any]], *, id: int | None = None) -> Frame:
     """Response to a ``commands.catalog`` request: the gateway's slash-command
     catalog for the app's ``/`` drawer.
 
@@ -527,7 +560,8 @@ def commands_catalog(commands: List[Dict[str, Any]], *, id: Optional[int] = None
 # Sync frames (M3 outbox)
 # ---------------------------------------------------------------------------
 
-def sync_done(cursor: int, *, id: Optional[int] = None) -> Frame:
+
+def sync_done(cursor: int, *, id: int | None = None) -> Frame:
     """Terminal frame of a ``sync`` replay: the new cursor to persist."""
     return Frame(type=TYPE_SYNC_DONE, id=id, payload={"cursor": cursor})
 
@@ -536,20 +570,21 @@ def sync_done(cursor: int, *, id: Optional[int] = None) -> Frame:
 # History frame (full message history for a chat/thread)
 # ---------------------------------------------------------------------------
 
+
 def history(
     chat_id: str,
-    messages: List[Dict[str, Any]],
+    messages: list[dict[str, Any]],
     has_more: bool,
     *,
-    thread_id: Optional[str] = None,
-    oldest_message_id: Optional[str] = None,
-    id: Optional[int] = None,
+    thread_id: str | None = None,
+    oldest_message_id: str | None = None,
+    id: int | None = None,
 ) -> Frame:
     """Response to a ``history`` request: a page of final messages for a
     chat/thread, ordered oldest → newest. ``has_more`` signals older pages
     exist; ``oldest_message_id`` is the ``before_message_id`` for the next
     (older) page."""
-    payload: Dict[str, Any] = {
+    payload: dict[str, Any] = {
         "messages": messages,
         "has_more": has_more,
     }
@@ -568,12 +603,13 @@ def history(
 # Message deletion frames
 # ---------------------------------------------------------------------------
 
+
 def message_deleted(
     chat_id: str,
-    message_ids: List[str],
+    message_ids: list[str],
     *,
-    thread_id: Optional[str] = None,
-    id: Optional[int] = None,
+    thread_id: str | None = None,
+    id: int | None = None,
 ) -> Frame:
     """Broadcast: the given message(s) were deleted from a chat/thread.
 
@@ -595,18 +631,19 @@ def message_deleted(
 # Push / notification frames (M5)
 # ---------------------------------------------------------------------------
 
+
 def notification(
     chat_id: str,
     kind: str,
     title: str,
     body: str,
     *,
-    thread_id: Optional[str] = None,
-    ts: Optional[int] = None,
+    thread_id: str | None = None,
+    ts: int | None = None,
 ) -> Frame:
     """Event: a transient in-app banner (and a push mirror when the device is
     offline). ``kind`` is one of the ``NOTIF_*`` constants."""
-    payload: Dict[str, Any] = {"kind": kind, "title": title, "body": body}
+    payload: dict[str, Any] = {"kind": kind, "title": title, "body": body}
     if ts is not None:
         payload["ts"] = ts
     return Frame(
@@ -614,11 +651,9 @@ def notification(
     )
 
 
-def fcm_register(
-    fcm_token: Optional[str] = None, ntfy_topic: Optional[str] = None
-) -> Frame:
+def fcm_register(fcm_token: str | None = None, ntfy_topic: str | None = None) -> Frame:
     """Request: update the device's push tokens (FCM rotation / ntfy topic)."""
-    payload: Dict[str, Any] = {}
+    payload: dict[str, Any] = {}
     if fcm_token:
         payload["fcm_token"] = fcm_token
     if ntfy_topic:
@@ -640,6 +675,7 @@ def read_receipt(chat_id: str, message_id: str) -> Frame:
 # Gateway health frame (M5)
 # ---------------------------------------------------------------------------
 
+
 def status(state: str) -> Frame:
     """Gateway health state (``state`` is one of the ``STATUS_*`` constants)."""
     return Frame(type=TYPE_STATUS, payload={"state": state})
@@ -649,6 +685,7 @@ def status(state: str) -> Frame:
 # Media frames (M4)
 # ---------------------------------------------------------------------------
 
+
 def media_offer(
     media_id: str,
     kind: str,
@@ -656,16 +693,16 @@ def media_offer(
     size: int,
     filename: str,
     *,
-    chat_id: Optional[str] = None,
-    thread_id: Optional[str] = None,
-    message_id: Optional[str] = None,
+    chat_id: str | None = None,
+    thread_id: str | None = None,
+    message_id: str | None = None,
 ) -> Frame:
     """Event: the agent produced media the app can fetch via ``media.pull``.
 
     ``message_id`` (optional) associates the offer with the assistant message
     it belongs to (the app falls back to the lane's last assistant message).
     """
-    payload: Dict[str, Any] = {
+    payload: dict[str, Any] = {
         "media_id": media_id,
         "kind": kind,
         "mime": mime,
@@ -674,15 +711,17 @@ def media_offer(
     }
     if message_id:
         payload["message_id"] = message_id
-    return Frame(type=TYPE_MEDIA_OFFER, chat_id=chat_id, thread_id=thread_id, payload=payload)
+    return Frame(
+        type=TYPE_MEDIA_OFFER, chat_id=chat_id, thread_id=thread_id, payload=payload
+    )
 
 
-def media_pull_end(ok: bool, *, id: Optional[int] = None) -> Frame:
+def media_pull_end(ok: bool, *, id: int | None = None) -> Frame:
     """Terminal frame of a ``media.pull`` binary stream."""
     return Frame(type=TYPE_MEDIA_PULL_END, id=id, payload={"ok": ok})
 
 
-def media_upload_ack(ok: bool, media_ref: str, *, id: Optional[int] = None) -> Frame:
+def media_upload_ack(ok: bool, media_ref: str, *, id: int | None = None) -> Frame:
     """Response to ``media.upload.end``: the ref is cached and may be used in
     a ``message.send`` ``media_refs``. Failures use ``error`` frames instead."""
     return Frame(
@@ -692,12 +731,12 @@ def media_upload_ack(ok: bool, media_ref: str, *, id: Optional[int] = None) -> F
     )
 
 
-def error(code: str, message: str, *, id: Optional[int] = None) -> Frame:
+def error(code: str, message: str, *, id: int | None = None) -> Frame:
     return Frame(type=TYPE_ERROR, id=id, payload={"code": code, "message": message})
 
 
-def pong(ts: Optional[int] = None) -> Frame:
-    payload: Dict[str, Any] = {}
+def pong(ts: int | None = None) -> Frame:
+    payload: dict[str, Any] = {}
     if ts is not None:
         payload["ts"] = ts
     return Frame(type=TYPE_PONG, payload=payload)

gateway-plugin/ws_server.py

@@ -290,6 +290,9 @@ class WsServer:
             server_caps=self._adapter.server_caps(),
             sync_cursor=self._adapter._outbox.latest_cursor(),
             channels=self._adapter.channel_list(),
+            # M5: lets the app dedupe sync-replayed notifications that
+            # already woke this device via push (docs/08 §8.7).
+            last_pushed_cursor=self._adapter._devices.last_pushed_cursor(device_id),
         )
         try:
             await ws.send(ack.to_json())