From f63b8601056211e2b191f6ca8ca29de5ee472a45 Mon Sep 17 00:00:00 2001
From: Matheus Cardoso <matheus@cardo.so>
Date: Mon, 29 Jun 2026 11:26:17 -0300
Subject: [PATCH] regression: private room access denial shows delayed generic
 error

---
 .../views/room/hooks/useOpenRoom.spec.ts      | 57 +++++++++++++++++++
 .../client/views/room/hooks/useOpenRoom.ts    | 10 +++-
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/apps/meteor/client/views/room/hooks/useOpenRoom.spec.ts b/apps/meteor/client/views/room/hooks/useOpenRoom.spec.ts
index ee74b74b09728..82a160f1e9118 100644
--- a/apps/meteor/client/views/room/hooks/useOpenRoom.spec.ts
+++ b/apps/meteor/client/views/room/hooks/useOpenRoom.spec.ts
@@ -3,6 +3,7 @@ import { renderHook, waitFor } from '@testing-library/react';
 
 import { useOpenRoom } from './useOpenRoom';
 import { createFakeRoom, createFakeSubscription } from '../../../../tests/mocks/data';
+import { RoomNotFoundError } from '../../../lib/errors/RoomNotFoundError';
 import { Rooms, Subscriptions } from '../../../stores';
 
 jest.mock('../../../../app/ui-utils/client', () => ({
@@ -76,4 +77,60 @@ describe('useOpenRoom', () => {
 			expect(result.current.data?.rid).toBe(dmRid);
 		});
 	});
+
+	describe('error classification', () => {
+		it('maps error-no-permission to RoomNotFoundError without retrying (regression for #40991)', async () => {
+			const getRoomByTypeAndName = jest.fn().mockImplementation(() => {
+				throw Object.assign(new Error('No permission'), { error: 'error-no-permission' });
+			});
+
+			const { result } = renderHook(() => useOpenRoom({ type: 'p', reference: 'private-channel' }), {
+				wrapper: mockAppRoot().withJohnDoe().withMethod('getRoomByTypeAndName', getRoomByTypeAndName).build(),
+			});
+
+			await waitFor(() => expect(result.current.isError).toBe(true));
+			expect(result.current.error).toBeInstanceOf(RoomNotFoundError);
+			expect(getRoomByTypeAndName).toHaveBeenCalledTimes(1);
+		});
+
+		it('maps error-invalid-room to RoomNotFoundError without retrying for non-DM rooms', async () => {
+			const getRoomByTypeAndName = jest.fn().mockImplementation(() => {
+				throw Object.assign(new Error('Invalid room'), { error: 'error-invalid-room' });
+			});
+
+			const { result } = renderHook(() => useOpenRoom({ type: 'c', reference: 'missing-channel' }), {
+				wrapper: mockAppRoot().withJohnDoe().withMethod('getRoomByTypeAndName', getRoomByTypeAndName).build(),
+			});
+
+			await waitFor(() => expect(result.current.isError).toBe(true));
+			expect(result.current.error).toBeInstanceOf(RoomNotFoundError);
+			expect(getRoomByTypeAndName).toHaveBeenCalledTimes(1);
+		});
+
+		it('retries unclassified transient errors and recovers on a later attempt', async () => {
+			const channelRid = 'channel-rid-transient';
+			const channelName = 'flaky-channel';
+			const channelRoom = createFakeRoom({ _id: channelRid, t: 'c', name: channelName });
+
+			const getRoomByTypeAndName = jest
+				.fn()
+				.mockImplementationOnce(() => {
+					throw new Error('network down');
+				})
+				.mockImplementation(() => channelRoom);
+
+			const { result } = renderHook(() => useOpenRoom({ type: 'c', reference: channelName }), {
+				wrapper: mockAppRoot()
+					.withJohnDoe()
+					.withPermission('preview-c-room')
+					.withMethod('getRoomByTypeAndName', getRoomByTypeAndName)
+					.build(),
+			});
+
+			// Backoff is Math.min(1000 * 2 ** attempt, 5000); first retry fires after ~1s.
+			await waitFor(() => expect(result.current.isSuccess).toBe(true), { timeout: 3000 });
+			expect(result.current.data?.rid).toBe(channelRid);
+			expect(getRoomByTypeAndName).toHaveBeenCalledTimes(2);
+		});
+	});
 });
diff --git a/apps/meteor/client/views/room/hooks/useOpenRoom.ts b/apps/meteor/client/views/room/hooks/useOpenRoom.ts
index 50fbae6be3a21..ed6e6547751ae 100644
--- a/apps/meteor/client/views/room/hooks/useOpenRoom.ts
+++ b/apps/meteor/client/views/room/hooks/useOpenRoom.ts
@@ -78,9 +78,15 @@ export function useOpenRoom({ type, reference }: { type: RoomType; reference: st
 			try {
 				roomData = await getRoomByTypeAndName(type, reference);
 			} catch (error) {
-				const isDefinitivelyNotFound = error && typeof error === 'object' && 'error' in error && error.error === 'error-invalid-room';
+				const errorCode = error && typeof error === 'object' && 'error' in error ? error.error : undefined;
 
-				if (!isDefinitivelyNotFound) {
+				// "No permission" means the room exists but the user can't see it — surface the
+				// not-found/no-access screen rather than retrying it as a transient failure.
+				if (errorCode === 'error-no-permission') {
+					throw new RoomNotFoundError(undefined, { type, reference });
+				}
+
+				if (errorCode !== 'error-invalid-room') {
 					throw error;
 				}