diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostResponseFileChanges.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostResponseFileChanges.ts
index 1da734f7c3f..7e9e3cf30b4 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostResponseFileChanges.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostResponseFileChanges.ts
@@ -4,7 +4,8 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { Disposable } from '../../../../../../base/common/lifecycle.js';
-import { constObservable, derived, IObservable, observableFromEvent } from '../../../../../../base/common/observable.js';
+import { constObservable, derived, derivedOpts, IObservable, observableFromEvent } from '../../../../../../base/common/observable.js';
+import { isEqual } from '../../../../../../base/common/resources.js';
 import { isDefined } from '../../../../../../base/common/types.js';
 import { URI } from '../../../../../../base/common/uri.js';
 import { IAgentConnection } from '../../../../../../platform/agentHost/common/agentService.js';
@@ -64,7 +65,7 @@ export class AgentHostResponseFileChangesProvider extends Disposable implements
 		// the summary stays empty (and self-hidden) for them.
 		const sessionStateObs = this._subscribe<SessionState>(StateComponents.Session, constObservable(backendSession));
 
-		const turnChangesetUriObs = derived(reader => {
+		const turnChangesetUriObs = derivedOpts<URI | undefined>({ equalsFn: isEqual }, reader => {
 			const sessionState = sessionStateObs.read(reader).read(reader);
 			if (!sessionState || sessionState instanceof Error) {
 				return undefined;
diff --git a/src/vs/workbench/contrib/chat/test/browser/agentHost/agentHostResponseFileChanges.test.ts b/src/vs/workbench/contrib/chat/test/browser/agentHost/agentHostResponseFileChanges.test.ts
index 0777f22c9fb..7929a699f07 100644
--- a/src/vs/workbench/contrib/chat/test/browser/agentHost/agentHostResponseFileChanges.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/agentHost/agentHostResponseFileChanges.test.ts
@@ -22,14 +22,20 @@ class FakeAgentConnection extends mock<IAgentConnection>() {
 
 	private readonly _emitters = new Map<string, Emitter<unknown>>();
 	private readonly _values = new Map<string, unknown>();
+	private readonly _subscriptionCounts = new Map<string, number>();
 
 	setState(resource: string, value: unknown): void {
 		this._values.set(resource, value);
 		this._emitters.get(resource)?.fire(value);
 	}
 
+	getSubscriptionCount(resource: string): number {
+		return this._subscriptionCounts.get(resource) ?? 0;
+	}
+
 	override getSubscription<T extends StateComponents>(_kind: T, resource: URI, _owner: string): IReference<IAgentSubscription<never>> {
 		const key = resource.toString();
+		this._subscriptionCounts.set(key, (this._subscriptionCounts.get(key) ?? 0) + 1);
 		let emitter = this._emitters.get(key);
 		if (!emitter) {
 			emitter = new Emitter<unknown>();
@@ -93,6 +99,24 @@ suite('AgentHostResponseFileChangesProvider', () => {
 		]);
 	});
 
+	test('keeps the changeset subscription when session state updates', () => {
+		const ds = store.add(new DisposableStore());
+		const conn = new FakeAgentConnection();
+		const provider = ds.add(new AgentHostResponseFileChangesProvider(conn, authority, () => backendSession));
+
+		conn.setState(backendSession.toString(), sessionStateWithTurnSupport());
+		conn.setState(turnChangesetUri('t1'), { status: ChangesetStatus.Ready, files: [] } satisfies ChangesetState);
+		observe(provider, ds);
+		const subscriptionCountBeforeUpdate = conn.getSubscriptionCount(turnChangesetUri('t1'));
+
+		conn.setState(backendSession.toString(), sessionStateWithTurnSupport());
+
+		assert.deepStrictEqual([
+			subscriptionCountBeforeUpdate,
+			conn.getSubscriptionCount(turnChangesetUri('t1')),
+		], [1, 1]);
+	});
+
 	test('returns empty when the agent does not advertise a turn changeset', () => {
 		const ds = store.add(new DisposableStore());
 		const conn = new FakeAgentConnection();