diff --git a/packages/cli/src/modules/chat-hub/__tests__/chat-hub.controller.test.ts b/packages/cli/src/modules/chat-hub/__tests__/chat-hub.controller.test.ts
index 5af2eb42ead..d1775af29e9 100644
--- a/packages/cli/src/modules/chat-hub/__tests__/chat-hub.controller.test.ts
+++ b/packages/cli/src/modules/chat-hub/__tests__/chat-hub.controller.test.ts
@@ -297,6 +297,23 @@ describe('ChatHubController', () => {
 			expect(await handlerSettled).toEqual({ error: undefined });
 		});
 
+		it('should reject when the file stream closes before it ends', async () => {
+			const stream = await openFileStream();
+			chatAttachmentService.getAttachment.mockResolvedValue(attachmentResult(stream));
+			const { port, handlerSettled } = await startAttachmentServer();
+
+			const clientReq = request(port);
+			clientReq.on('response', (clientRes) => {
+				clientRes.once('data', () => stream.destroy());
+				clientRes.on('error', () => {});
+			});
+
+			expect(await handlerSettled).toEqual({
+				error: expect.objectContaining({ code: 'ERR_STREAM_PREMATURE_CLOSE' }),
+			});
+			await vi.waitFor(() => expect(stream.closed).toBe(true), { timeout: CLOSE_TIMEOUT_MS });
+		});
+
 		it('should close the file stream and settle when the client disconnects before the response starts', async () => {
 			const stream = await openFileStream();
 			const requestReceived = createDeferredPromise();
diff --git a/packages/cli/src/modules/chat-hub/chat-hub.controller.ts b/packages/cli/src/modules/chat-hub/chat-hub.controller.ts
index c9a5b39a05d..a3a45e85070 100644
--- a/packages/cli/src/modules/chat-hub/chat-hub.controller.ts
+++ b/packages/cli/src/modules/chat-hub/chat-hub.controller.ts
@@ -164,12 +164,20 @@ export class ChatHubController {
 			return;
 		}
 
+		// pipeline also rejects with ERR_STREAM_PREMATURE_CLOSE when the source closes early,
+		// so only treat it as a disconnect if the response closed while the source was open.
+		let clientDisconnected = false;
+		res.once('close', () => {
+			clientDisconnected = !res.writableFinished && !stream.destroyed;
+		});
+
 		// pipeline destroys the source when the client disconnects during the download,
 		// so aborted downloads don't leak file descriptors.
 		try {
 			await pipeline(stream, res);
 		} catch (error) {
 			if (
+				clientDisconnected &&
 				error instanceof Error &&
 				'code' in error &&
 				error.code === 'ERR_STREAM_PREMATURE_CLOSE'