diff --git a/desktop/src/features/channels/ui/ChannelPane.tsx b/desktop/src/features/channels/ui/ChannelPane.tsx
index 8b8a4101ce..131c9df0e1 100644
--- a/desktop/src/features/channels/ui/ChannelPane.tsx
+++ b/desktop/src/features/channels/ui/ChannelPane.tsx
@@ -1,5 +1,5 @@
 import * as React from "react";
-import { Hash, LogIn } from "lucide-react";
+import { Hash, LoaderCircle, LogIn } from "lucide-react";
 import { AnimatePresence } from "motion/react";
 import { useAppNavigation } from "@/app/navigation/useAppNavigation";
 import { useMediaUpload } from "@/features/messages/lib/useMediaUpload";
@@ -87,6 +87,7 @@ export const ChannelPane = React.memo(function ChannelPane({
   isMessageUnreadById,
   isJoining = false,
   isSinglePanelView = false,
+  isAgentSessionLoading = false,
   isSending,
   isTimelineLoading,
   entranceMessageId = null,
@@ -914,6 +915,30 @@ export const ChannelPane = React.memo(function ChannelPane({
             );
             return wrapAux(panel, "agent-session-thread-panel");
           })()
+        ) : isSinglePanelView && openAgentSessionPubkey ? (
+          <div
+            className="flex min-h-0 flex-1 items-center justify-center p-8 text-center"
+            data-testid="agent-session-unavailable"
+          >
+            <div className="max-w-sm space-y-2">
+              {isAgentSessionLoading ? (
+                <LoaderCircle
+                  aria-hidden="true"
+                  className="mx-auto h-5 w-5 animate-spin text-muted-foreground"
+                />
+              ) : null}
+              <h1 className="text-lg font-semibold">
+                {isAgentSessionLoading
+                  ? "Loading agent activity…"
+                  : "Agent activity unavailable"}
+              </h1>
+              <p className="text-sm text-muted-foreground">
+                {isAgentSessionLoading
+                  ? "Buzz is finding this agent."
+                  : "This agent is no longer available in this community. You can close this window and open another activity feed from Buzz."}
+              </p>
+            </div>
+          </div>
         ) : profilePanelPubkey ? (
           (() => {
             const panel = (
diff --git a/desktop/src/features/channels/ui/ChannelPane.types.ts b/desktop/src/features/channels/ui/ChannelPane.types.ts
index 62b9f8a645..be746d4c62 100644
--- a/desktop/src/features/channels/ui/ChannelPane.types.ts
+++ b/desktop/src/features/channels/ui/ChannelPane.types.ts
@@ -54,6 +54,7 @@ export type ChannelPaneProps = {
   isHuddleTranscript?: boolean;
   isJoining?: boolean;
   isSinglePanelView?: boolean;
+  isAgentSessionLoading?: boolean;
   isSending: boolean;
   isTimelineLoading: boolean;
   /** Newly-created message that should receive the one-shot conversation arrival motion. */
diff --git a/desktop/src/features/channels/ui/ChannelScreen.tsx b/desktop/src/features/channels/ui/ChannelScreen.tsx
index 3d2bee490e..626b8cd396 100644
--- a/desktop/src/features/channels/ui/ChannelScreen.tsx
+++ b/desktop/src/features/channels/ui/ChannelScreen.tsx
@@ -306,6 +306,10 @@ export function ChannelScreen({
     welcomeGuideAgent,
   });
   const relayAgentsQuery = useRelayAgentsQuery();
+  const agentsLoading =
+    channelMembersQuery.isLoading ||
+    managedAgentsQuery.isLoading ||
+    relayAgentsQuery.isLoading;
   const relayAgents = relayAgentsQuery.data ?? [];
   const knownAgentPubkeys = React.useMemo(
     () =>
@@ -568,16 +572,14 @@ export function ChannelScreen({
   } = useChannelAgentSessions({
     activeChannel,
     activeChannelId,
-    agentsLoaded:
-      !channelMembersQuery.isLoading &&
-      !managedAgentsQuery.isLoading &&
-      !relayAgentsQuery.isLoading,
+    agentsLoaded: !agentsLoading,
     channelMembers,
     handleOpenThread,
     managedAgents: agentSessionCandidates,
     openAgentSessionPubkey,
     openThreadHeadId: effectiveOpenThreadHeadId,
     profilePanelPubkey,
+    preserveUnresolvedSession: isDedicatedActivityWindow,
     setChannelManagementOpen,
     setExpandedThreadReplyIds,
     setOpenAgentSessionChannelId,
@@ -890,6 +892,7 @@ export function ChannelScreen({
                   isMessageUnreadById={isMessageUnread}
                   isFollowingThread={isNotifiedForEffectiveThread}
                   isSending={sendMessageMutation.isPending}
+                  isAgentSessionLoading={agentsLoading}
                   isSinglePanelView={isSinglePanelView}
                   isTimelineLoading={isTimelineLoading}
                   messages={timelineMessages}
diff --git a/desktop/src/features/channels/ui/useChannelAgentSessions.test.mjs b/desktop/src/features/channels/ui/useChannelAgentSessions.test.mjs
new file mode 100644
index 0000000000..68372aa2fb
--- /dev/null
+++ b/desktop/src/features/channels/ui/useChannelAgentSessions.test.mjs
@@ -0,0 +1,31 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { shouldClearUnresolvedAgentSession } from "./useChannelAgentSessions.ts";
+
+const unresolvedSession = {
+  agentSessionAgents: [],
+  agentsLoaded: true,
+  openAgentSessionPubkey: "agent-pubkey",
+  profilePanelPubkey: null,
+};
+
+test("dedicated activity windows preserve unresolved sessions for an empty state", () => {
+  assert.equal(
+    shouldClearUnresolvedAgentSession({
+      ...unresolvedSession,
+      preserveUnresolvedSession: true,
+    }),
+    false,
+  );
+});
+
+test("the in-app panel still clears stale unresolved sessions", () => {
+  assert.equal(
+    shouldClearUnresolvedAgentSession({
+      ...unresolvedSession,
+      preserveUnresolvedSession: false,
+    }),
+    true,
+  );
+});
diff --git a/desktop/src/features/channels/ui/useChannelAgentSessions.ts b/desktop/src/features/channels/ui/useChannelAgentSessions.ts
index 20c561e798..cb4dc0e3a6 100644
--- a/desktop/src/features/channels/ui/useChannelAgentSessions.ts
+++ b/desktop/src/features/channels/ui/useChannelAgentSessions.ts
@@ -39,6 +39,7 @@ type UseChannelAgentSessionsOptions = {
   openAgentSessionPubkey: string | null;
   openThreadHeadId: string | null;
   profilePanelPubkey?: string | null;
+  preserveUnresolvedSession?: boolean;
   setChannelManagementOpen: (open: boolean) => void;
   setExpandedThreadReplyIds: (value: Set<string>) => void;
   setOpenAgentSessionChannelId: PanelValueSetter;
@@ -163,6 +164,33 @@ export function getChannelAgentSessionAgents({
   });
 }
 
+export function shouldClearUnresolvedAgentSession({
+  agentSessionAgents,
+  agentsLoaded,
+  openAgentSessionPubkey,
+  preserveUnresolvedSession,
+  profilePanelPubkey,
+}: {
+  agentSessionAgents: ChannelAgentSessionAgent[];
+  agentsLoaded: boolean;
+  openAgentSessionPubkey: string | null;
+  preserveUnresolvedSession: boolean;
+  profilePanelPubkey: string | null;
+}): boolean {
+  return Boolean(
+    openAgentSessionPubkey &&
+      !preserveUnresolvedSession &&
+      agentsLoaded &&
+      normalizePubkey(profilePanelPubkey ?? "") !==
+        normalizePubkey(openAgentSessionPubkey) &&
+      !agentSessionAgents.some(
+        (agent) =>
+          normalizePubkey(agent.pubkey) ===
+          normalizePubkey(openAgentSessionPubkey),
+      ),
+  );
+}
+
 export function useChannelAgentSessions({
   activeChannel,
   activeChannelId,
@@ -173,6 +201,7 @@ export function useChannelAgentSessions({
   openAgentSessionPubkey,
   openThreadHeadId,
   profilePanelPubkey = null,
+  preserveUnresolvedSession = false,
   setChannelManagementOpen,
   setExpandedThreadReplyIds,
   setOpenAgentSessionChannelId,
@@ -298,15 +327,13 @@ export function useChannelAgentSessions({
     // agent queries have settled. Once loaded, a channel that legitimately has
     // zero agents will still auto-close a stale param.
     if (
-      openAgentSessionPubkey &&
-      agentsLoaded &&
-      normalizePubkey(profilePanelPubkey ?? "") !==
-        normalizePubkey(openAgentSessionPubkey) &&
-      !agentSessionAgents.some(
-        (agent) =>
-          normalizePubkey(agent.pubkey) ===
-          normalizePubkey(openAgentSessionPubkey),
-      )
+      shouldClearUnresolvedAgentSession({
+        agentSessionAgents,
+        agentsLoaded,
+        openAgentSessionPubkey,
+        preserveUnresolvedSession,
+        profilePanelPubkey,
+      })
     ) {
       returnTarget.clear();
       setOpenAgentSessionPubkey(null, { replace: true });
@@ -315,6 +342,7 @@ export function useChannelAgentSessions({
     agentSessionAgents,
     agentsLoaded,
     openAgentSessionPubkey,
+    preserveUnresolvedSession,
     profilePanelPubkey,
     returnTarget,
     setOpenAgentSessionPubkey,