Guard ChatTipService against disposed scoped context key service

src/vs/workbench/contrib/chat/browser/chatTipService.ts

@@ -521,7 +521,18 @@ export class ChatTipService extends Disposable implements IChatTipService {
 			return;
 		}
 
-		if (this._isEligible(this._shownTip, this._contextKeyService)) {
+		let eligible: boolean;
+		try {
+			eligible = this._isEligible(this._shownTip, this._contextKeyService);
+		} catch (err) {
+			// The stored scoped context key service may have been disposed
+			// (e.g. its owning chat widget was torn down). Drop the stale
+			// reference and bail out — there is nothing meaningful to hide.
+			this._contextKeyService = undefined;
+			return;
+		}
+
+		if (eligible) {
 			return;
 		}
 

src/vs/workbench/contrib/chat/test/browser/chatTipService.test.ts

@@ -1725,6 +1725,37 @@ suite('ChatTipService', () => {
 		assert.strictEqual(tracker.isExcluded(tip), true, 'Should be excluded after refresh finds instruction files');
 	});
 
+	test('does not throw when submitted while stored context key service has been disposed', () => {
+		const submitRequestEmitter = testDisposables.add(new Emitter<{ readonly chatSessionResource: URI; readonly message?: IParsedChatRequest }>());
+		instantiationService.stub(IChatService, {
+			onDidSubmitRequest: submitRequestEmitter.event,
+			getSession: () => undefined,
+		} as Partial<IChatService> as IChatService);
+
+		const service = createService();
+
+		// Acquire a tip so the service stashes the (scoped) context key service.
+		const tip = service.getWelcomeTip(contextKeyService);
+		assert.ok(tip);
+
+		// Simulate the owning chat widget being torn down, which disposes its
+		// scoped context key service. Subsequent contextMatchesRules calls then
+		// throw "AbstractContextKeyService has been disposed".
+		const originalContextMatchesRules = contextKeyService.contextMatchesRules.bind(contextKeyService);
+		contextKeyService.contextMatchesRules = () => {
+			throw new Error('AbstractContextKeyService has been disposed');
+		};
+
+		try {
+			assert.doesNotThrow(() => submitRequestEmitter.fire({
+				chatSessionResource: URI.parse('chat:session-disposed'),
+				message: { text: 'hello', parts: [] },
+			}));
+		} finally {
+			contextKeyService.contextMatchesRules = originalContextMatchesRules;
+		}
+	});
+
 });
 
 suite('CreateSlashCommandsUsageTracker', () => {