diff --git a/desktop/scripts/check-file-sizes.mjs b/desktop/scripts/check-file-sizes.mjs
index 9eedcf252c..93deda4c80 100644
--- a/desktop/scripts/check-file-sizes.mjs
+++ b/desktop/scripts/check-file-sizes.mjs
@@ -33,7 +33,7 @@ const overrides = new Map([
   ["src/app/AppShell.tsx", 750],
   ["src/features/channels/hooks.ts", 525], // canvas query + mutation hooks
   ["src/features/channels/ui/ChannelManagementSheet.tsx", 800],
-  ["src/features/messages/ui/MessageComposer.tsx", 650], // media upload handlers (paste, drop, dialog)
+  ["src/features/messages/ui/MessageComposer.tsx", 665], // media upload handlers (paste, drop, dialog) + channelId reset effect
   ["src/features/settings/ui/SettingsView.tsx", 600],
   ["src/features/sidebar/ui/AppSidebar.tsx", 850], // channels + forums creation forms
   ["src/features/tokens/ui/TokenSettingsCard.tsx", 800],
diff --git a/desktop/src/app/AppShell.tsx b/desktop/src/app/AppShell.tsx
index 20d75f44ea..e080b41a30 100644
--- a/desktop/src/app/AppShell.tsx
+++ b/desktop/src/app/AppShell.tsx
@@ -217,14 +217,6 @@ export function AppShell() {
         .filter((value) => value && value.trim().length > 0)
         .join(" ") || "Channel details and activity."
     : "Connect to the relay to browse channels and read messages.";
-  const contentPaneKey =
-    selectedView === "home"
-      ? "home"
-      : selectedView === "agents"
-        ? "agents"
-        : selectedView === "settings"
-          ? "settings"
-          : `channel:${activeChannel?.id ?? "none"}`;
   const shouldLoadTimeline =
     activeChannel !== null && activeChannel.channelType !== "forum";
   const isTimelineLoading =
@@ -589,10 +581,7 @@ export function AppShell() {
             unreadChannelIds={unreadChannelIds}
           />
 
-          <SidebarInset
-            className="min-h-0 min-w-0 overflow-hidden"
-            key={contentPaneKey}
-          >
+          <SidebarInset className="min-h-0 min-w-0 overflow-hidden">
             {selectedView === "home" ? (
               <ChatHeader
                 description="Personalized feed for mentions, reminders, channel activity, and agent work."
diff --git a/desktop/src/app/ChannelPane.tsx b/desktop/src/app/ChannelPane.tsx
index fd1e656ba5..7178fbe000 100644
--- a/desktop/src/app/ChannelPane.tsx
+++ b/desktop/src/app/ChannelPane.tsx
@@ -51,8 +51,9 @@ export function ChannelPane({
   typingPubkeys,
 }: ChannelPaneProps) {
   return (
-    <React.Fragment key={activeChannel?.id ?? "no-channel"}>
+    <React.Fragment>
       <MessageTimeline
+        channelId={activeChannel?.id}
         activeReplyTargetId={replyTargetId}
         currentPubkey={currentPubkey}
         profiles={profiles}
diff --git a/desktop/src/features/messages/ui/MessageComposer.tsx b/desktop/src/features/messages/ui/MessageComposer.tsx
index 6f88f52d3b..a391b952d7 100644
--- a/desktop/src/features/messages/ui/MessageComposer.tsx
+++ b/desktop/src/features/messages/ui/MessageComposer.tsx
@@ -78,6 +78,20 @@ export function MessageComposer({
   }>({ status: "idle" });
   const [pendingImeta, setPendingImeta] = React.useState<BlobDescriptor[]>([]);
 
+  // biome-ignore lint/correctness/useExhaustiveDependencies: channelId is the sole trigger — reset all composer state on channel switch to prevent draft/upload/mention leaks
+  React.useEffect(() => {
+    setContent("");
+    setPendingImeta([]);
+    setUploadState({ status: "idle" });
+    setMentionQuery(null);
+    setMentionStartIndex(0);
+    setMentionSelectedIndex(0);
+    setIsEmojiPickerOpen(false);
+    mentionMapRef.current.clear();
+    draftSelectionRef.current = { end: 0, start: 0 };
+    pendingSelectionRef.current = null;
+  }, [channelId]);
+
   const membersQuery = useChannelMembersQuery(channelId);
   const members = membersQuery.data ?? [];
   const managedAgentsQuery = useManagedAgentsQuery();
diff --git a/desktop/src/features/messages/ui/MessageTimeline.tsx b/desktop/src/features/messages/ui/MessageTimeline.tsx
index 1a991d43ec..17d6937c8f 100644
--- a/desktop/src/features/messages/ui/MessageTimeline.tsx
+++ b/desktop/src/features/messages/ui/MessageTimeline.tsx
@@ -11,6 +11,7 @@ import { TimelineSkeleton } from "./TimelineSkeleton";
 import { useTimelineScrollManager } from "./useTimelineScrollManager";
 
 type MessageTimelineProps = {
+  channelId?: string | null;
   messages: TimelineMessage[];
   isLoading?: boolean;
   emptyTitle?: string;
@@ -29,6 +30,7 @@ type MessageTimelineProps = {
 };
 
 export function MessageTimeline({
+  channelId,
   messages,
   isLoading = false,
   emptyTitle = "No messages yet",
@@ -51,6 +53,7 @@ export function MessageTimeline({
     syncScrollState,
     timelineRef,
   } = useTimelineScrollManager({
+    channelId,
     isLoading,
     messages,
     onTargetReached,
diff --git a/desktop/src/features/messages/ui/useTimelineScrollManager.ts b/desktop/src/features/messages/ui/useTimelineScrollManager.ts
index b7b2b8de23..ff6ca211bf 100644
--- a/desktop/src/features/messages/ui/useTimelineScrollManager.ts
+++ b/desktop/src/features/messages/ui/useTimelineScrollManager.ts
@@ -4,11 +4,13 @@ import type { TimelineMessage } from "@/features/messages/types";
 import { isNearBottom } from "./messageTimelineUtils";
 
 export function useTimelineScrollManager({
+  channelId,
   isLoading,
   messages,
   onTargetReached,
   targetMessageId,
 }: {
+  channelId?: string | null;
   isLoading: boolean;
   messages: TimelineMessage[];
   onTargetReached?: (messageId: string) => void;
@@ -32,6 +34,24 @@ export function useTimelineScrollManager({
     string | null
   >(null);
   const [newMessageCount, setNewMessageCount] = React.useState(0);
+
+  // biome-ignore lint/correctness/useExhaustiveDependencies: channelId is intentionally the sole trigger — we reset all scroll state when the channel changes
+  React.useLayoutEffect(() => {
+    hasInitializedRef.current = false;
+    shouldStickToBottomRef.current = true;
+    isAtBottomRef.current = true;
+    isProgrammaticBottomScrollRef.current = false;
+    previousTimelineHeightRef.current = null;
+    previousScrollTopRef.current = 0;
+    lockedScrollTopRef.current = null;
+    previousLastMessageIdRef.current = undefined;
+    previousMessageCountRef.current = 0;
+    handledTargetMessageIdRef.current = null;
+    setIsAtBottom(true);
+    setHighlightedMessageId(null);
+    setNewMessageCount(0);
+  }, [channelId]);
+
   const latestMessage =
     messages.length > 0 ? messages[messages.length - 1] : undefined;
 
diff --git a/desktop/src/main.tsx b/desktop/src/main.tsx
index 6831a4dfb0..579da46e67 100644
--- a/desktop/src/main.tsx
+++ b/desktop/src/main.tsx
@@ -13,6 +13,10 @@ const queryClient = new QueryClient({
     queries: {
       retry: 1,
       refetchOnWindowFocus: false,
+      networkMode: "always",
+    },
+    mutations: {
+      networkMode: "always",
     },
   },
 });