diff --git a/kez-chat/web/src/routes/Messages.svelte b/kez-chat/web/src/routes/Messages.svelte
index 70c8086..2f5316e 100644
--- a/kez-chat/web/src/routes/Messages.svelte
+++ b/kez-chat/web/src/routes/Messages.svelte
@@ -572,7 +572,7 @@
     // new message lands. The service is already running (it started on
     // session unlock in store.svelte.ts) regardless of which route the
     // user was on.
-    unsubscribe = inboxService.onMessage(() => void refresh());
+    unsubscribe = inboxService.onMessage(() => void onInboxMessage());
     // Landing here = the user has seen new messages; reset the badge.
     inboxService.markAllRead();
     // Relay state poll.
@@ -580,6 +580,7 @@
       relayStatuses = getRelayStatuses();
     }, 2_000);
     document.addEventListener("click", onDocumentClick);
+    document.addEventListener("visibilitychange", onVisibilityChange);
     void evaluatePushNudge();
   });
 
@@ -587,8 +588,27 @@
     unsubscribe?.();
     if (relayPollTimer) clearInterval(relayPollTimer);
     document.removeEventListener("click", onDocumentClick);
+    document.removeEventListener("visibilitychange", onVisibilityChange);
   });
 
+  /** A message landing in the thread the user is looking at is read on
+   *  arrival — don't badge it. Only while the page is visible: a
+   *  message that arrives while the app is backgrounded stays unread
+   *  until they come back (onVisibilityChange). */
+  async function onInboxMessage() {
+    const pk = activePrimary;
+    if (pk && document.visibilityState === "visible") {
+      await markConversationRead(pk);
+    }
+    await refresh();
+  }
+
+  function onVisibilityChange() {
+    const pk = activePrimary;
+    if (document.visibilityState !== "visible" || !pk) return;
+    void markConversationRead(pk).then(refresh);
+  }
+
   async function refresh() {
     conversations = await listConversations();
     // Kick off peer-profile fetches for any conversation whose peer