diff --git a/apps/mobile/src/features/threads/ThreadAgentsSheet.tsx b/apps/mobile/src/features/threads/ThreadAgentsSheet.tsx
index e78239955e4af..f21cde9deff4c 100644
--- a/apps/mobile/src/features/threads/ThreadAgentsSheet.tsx
+++ b/apps/mobile/src/features/threads/ThreadAgentsSheet.tsx
@@ -141,9 +141,7 @@ function AgentRow(props: {
 }) {
   const { subagent } = props;
   const { presentationById } = useEnvironments();
-  const target = subagentThreadTarget(subagent, props.environmentId, (id) =>
-    presentationById.has(id),
-  );
+  const target = subagentThreadTarget(subagent, props.environmentId, presentationById);
 
   const row = (
     <View className="py-3.5">
@@ -164,7 +162,9 @@ function AgentRow(props: {
         accessibilityHint={
           subagent.remoteChild === undefined
             ? "Provider-managed agent. Its work appears in the transcript."
-            : `Runs on ${subagent.remoteChild.label}. Connect to it to open its thread.`
+            : presentationById.has(subagent.remoteChild.environmentId)
+              ? `Runs on ${subagent.remoteChild.label}. Turn it on in Settings to open its thread.`
+              : `Runs on ${subagent.remoteChild.label}. Connect to it to open its thread.`
         }
       >
         {row}
diff --git a/apps/mobile/src/features/threads/thread-subagent-group.tsx b/apps/mobile/src/features/threads/thread-subagent-group.tsx
index 734ebf4583e03..73f78051efab1 100644
--- a/apps/mobile/src/features/threads/thread-subagent-group.tsx
+++ b/apps/mobile/src/features/threads/thread-subagent-group.tsx
@@ -189,10 +189,8 @@ export function ThreadSubagentGroup(props: {
       {!grouped || expanded ? (
         <View className="mb-1 gap-px rounded-xl border border-border bg-card/30 p-1">
           {agents.map((agent) => {
-            // A task in a linked environment opens there, if this app is connected to it.
-            const target = subagentThreadTarget(agent, props.environmentId, (id) =>
-              presentationById.has(id),
-            );
+            // A task in a linked environment opens there, if it is enabled in this app.
+            const target = subagentThreadTarget(agent, props.environmentId, presentationById);
             return (
               <Pressable
                 key={agent.item.id}
diff --git a/apps/mobile/src/features/threads/threadAgentsPresentation.test.ts b/apps/mobile/src/features/threads/threadAgentsPresentation.test.ts
index 171d73a148597..3bccf4aa80dea 100644
--- a/apps/mobile/src/features/threads/threadAgentsPresentation.test.ts
+++ b/apps/mobile/src/features/threads/threadAgentsPresentation.test.ts
@@ -4,6 +4,7 @@ import {
   projectedSubagentsToRuntime,
 } from "@t3tools/client-runtime/state/subagentRuntime";
 import {
+  EnvironmentId,
   NodeId,
   ProviderDriverKind,
   RunId,
@@ -16,6 +17,7 @@ import {
   nextWorkflowSelection,
   resolveSubagentRowPresentation,
   resolveSubagentStopTarget,
+  subagentThreadTarget,
   workflowMemberDetail,
   workflowMemberMetadata,
   workflowRail,
@@ -350,3 +352,26 @@ describe("resolveSubagentStopTarget", () => {
     ).toBeNull();
   });
 });
+
+describe("subagentThreadTarget", () => {
+  const here = EnvironmentId.make("env-here");
+  const laptop = EnvironmentId.make("env-laptop");
+  const remote = {
+    childThreadId: null,
+    remoteChild: {
+      environmentId: laptop,
+      threadId: ThreadId.make("remote-thread"),
+      label: "Laptop",
+    },
+  };
+
+  it("opens a remote task only in an enabled saved environment", () => {
+    expect(
+      subagentThreadTarget(remote, here, new Map([[laptop, { entry: { enabled: true } }]])),
+    ).toEqual({ environmentId: laptop, threadId: "remote-thread" });
+    expect(
+      subagentThreadTarget(remote, here, new Map([[laptop, { entry: { enabled: false } }]])),
+    ).toBeNull();
+    expect(subagentThreadTarget(remote, here, new Map())).toBeNull();
+  });
+});
diff --git a/apps/mobile/src/features/threads/threadAgentsPresentation.ts b/apps/mobile/src/features/threads/threadAgentsPresentation.ts
index 64c9b232ed424..5f62fa2985e6a 100644
--- a/apps/mobile/src/features/threads/threadAgentsPresentation.ts
+++ b/apps/mobile/src/features/threads/threadAgentsPresentation.ts
@@ -35,19 +35,19 @@ export interface SubagentRowPresentation {
 
 /**
  * Where an agent's thread opens: here, or in the linked environment that runs
- * it. Null when there is no thread, or this app is not connected to that
- * environment.
+ * it. Null when there is no thread, or that environment is not saved and
+ * enabled in this app.
  */
 export function subagentThreadTarget(
   subagent: Pick<OrchestrationV2Subagent, "childThreadId" | "remoteChild">,
   environmentId: EnvironmentId,
-  isKnownEnvironment: (environmentId: EnvironmentId) => boolean,
+  environments: ReadonlyMap<EnvironmentId, { readonly entry: { readonly enabled: boolean } }>,
 ): { readonly environmentId: EnvironmentId; readonly threadId: ThreadId } | null {
   if (subagent.childThreadId !== null) {
     return { environmentId, threadId: subagent.childThreadId };
   }
   const remote = subagent.remoteChild;
-  return remote !== undefined && isKnownEnvironment(remote.environmentId)
+  return remote !== undefined && environments.get(remote.environmentId)?.entry.enabled === true
     ? { environmentId: remote.environmentId, threadId: remote.threadId }
     : null;
 }
diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
index 9c015a74b9b9b..0155cd1ad2382 100644
--- a/apps/web/src/components/ChatView.tsx
+++ b/apps/web/src/components/ChatView.tsx
@@ -938,8 +938,8 @@ export default function ChatView(props: ChatViewProps) {
     return {
       title: delegatedFromThread?.title ?? delegatedFrom.title,
       environmentLabel: delegatedFromEnvironment?.label ?? activeThread?.linkOrigin?.label ?? "",
-      // Only an environment this client is connected to can open the parent.
-      ...(delegatedFromEnvironment === null
+      // Only an environment enabled in this client can open the parent.
+      ...(delegatedFromEnvironment?.entry.enabled !== true
         ? {}
         : {
             open: (): void => {
diff --git a/apps/web/src/components/chat/ThreadRelationshipsControl.remote-parent.browser.test.tsx b/apps/web/src/components/chat/ThreadRelationshipsControl.remote-parent.browser.test.tsx
index 08108cd835885..d51bd6712bbda 100644
--- a/apps/web/src/components/chat/ThreadRelationshipsControl.remote-parent.browser.test.tsx
+++ b/apps/web/src/components/chat/ThreadRelationshipsControl.remote-parent.browser.test.tsx
@@ -41,7 +41,7 @@ vi.mock(import("../../state/entities"), async (original) => ({
 }));
 vi.mock(import("../../state/environments"), async (original) => ({
   ...(await original()),
-  useEnvironment: (() => ({ label: "Linked" })) as never,
+  useEnvironment: (() => ({ label: "Linked", entry: { enabled: true } })) as never,
 }));
 vi.mock(import("../ui/toast"), async (original) => {
   const actual = await original();
diff --git a/apps/web/src/components/chat/ThreadRelationshipsControl.tsx b/apps/web/src/components/chat/ThreadRelationshipsControl.tsx
index 23e0da34bf7f6..99769953ffbe1 100644
--- a/apps/web/src/components/chat/ThreadRelationshipsControl.tsx
+++ b/apps/web/src/components/chat/ThreadRelationshipsControl.tsx
@@ -268,6 +268,8 @@ function RemoteSubagentRow(props: {
 }) {
   const navigate = useNavigate();
   const environment = useEnvironment(props.agent.remoteChild.environmentId);
+  // A saved environment that is switched off can't open its threads.
+  const canOpen = environment?.entry.enabled === true;
   const { remoteChild } = props.agent;
   const status = props.agent.status;
   const failed = status === "failed";
@@ -285,9 +287,9 @@ function RemoteSubagentRow(props: {
               size="sm"
               variant="ghost"
               part="row"
-              aria-disabled={environment === null || undefined}
+              aria-disabled={!canOpen || undefined}
               onClick={() => {
-                if (environment === null) return;
+                if (!canOpen) return;
                 void navigate({
                   to: "/$environmentId/$threadId",
                   params: buildThreadRouteParams(
@@ -322,9 +324,11 @@ function RemoteSubagentRow(props: {
           <LineageTooltipContent
             title={title}
             hint={
-              environment === null
-                ? `Runs on ${remoteChild.label}. Connect to it to open the thread there.`
-                : `Open on ${remoteChild.label}`
+              canOpen
+                ? `Open on ${remoteChild.label}`
+                : environment === null
+                  ? `Runs on ${remoteChild.label}. Connect to it to open the thread there.`
+                  : `Runs on ${remoteChild.label}. Turn it on in Settings to open the thread there.`
             }
           />
         </TooltipPopup>
@@ -346,6 +350,7 @@ function DelegatedFromRow(props: {
   const router = useRouter();
   const { delegatedFrom } = props;
   const environment = useEnvironment(delegatedFrom.environmentId);
+  const canOpen = environment?.entry.enabled === true;
   const parentRef = scopeThreadRef(delegatedFrom.environmentId, delegatedFrom.threadId);
   // The title it had at delegation, until this client sees the parent itself.
   const parent = useQuietThreadShell(parentRef);
@@ -390,9 +395,9 @@ function DelegatedFromRow(props: {
               size="sm"
               variant="ghost"
               part="row"
-              aria-disabled={environment === null || undefined}
+              aria-disabled={!canOpen || undefined}
               onClick={() => {
-                if (environment === null) return;
+                if (!canOpen) return;
                 void openParent();
               }}
             />
@@ -418,9 +423,11 @@ function DelegatedFromRow(props: {
           <LineageTooltipContent
             title={title}
             hint={
-              environment === null
-                ? `Delegated from ${label ?? "a linked environment"}. Connect to it to open the parent thread.`
-                : `Open parent agent on ${environment.label}`
+              canOpen
+                ? `Open parent agent on ${label}`
+                : environment === null
+                  ? `Delegated from ${label ?? "a linked environment"}. Connect to it to open the parent thread.`
+                  : `Delegated from ${label}. Turn it on in Settings to open the parent thread.`
             }
           />
         </TooltipPopup>
diff --git a/apps/web/src/components/chat/V2LifecycleRow.tsx b/apps/web/src/components/chat/V2LifecycleRow.tsx
index 920586f6d1dbb..085b906ebe6f2 100644
--- a/apps/web/src/components/chat/V2LifecycleRow.tsx
+++ b/apps/web/src/components/chat/V2LifecycleRow.tsx
@@ -423,11 +423,11 @@ function SubagentTimelineLink(props: {
   const remoteEnvironment = useEnvironment(remote?.environmentId ?? null);
   const navigate = useNavigate();
   const threadId = props.threadId;
-  // A task in a linked environment opens there, if this client is connected to it.
+  // A task in a linked environment opens there, if it is enabled in this client.
   const open =
     threadId !== null
       ? () => props.onOpenThread(threadId)
-      : remote !== undefined && remoteEnvironment !== null
+      : remote !== undefined && remoteEnvironment?.entry.enabled === true
         ? () =>
             void navigate({
               to: "/$environmentId/$threadId",