fix: keep a rule made from a message out of a login switched to while the sheet was open

locales/rn/de.json

@@ -266,7 +266,10 @@
   },
   "context_menu": {
     "color_tag": "Label",
-    "remove_color": "Label entfernen"
+    "remove_color": "Label entfernen",
+    "rules": {
+      "login_changed": "Sie haben das Konto gewechselt, daher wurde die Regel nicht gespeichert"
+    }
   },
   "device_sync": {
     "auth_problem_text": "Der Server akzeptiert die Anmeldung von {account} nicht mehr, daher werden die Kontakte und Kalender dieses Kontos auf diesem Gerät nicht mehr synchronisiert. Melden Sie sich erneut an, um fortzufahren. Auf diesem Gerät vorgenommene Änderungen bleiben erhalten.",

locales/rn/en.json

@@ -275,7 +275,10 @@
   },
   "context_menu": {
     "color_tag": "Tag",
-    "remove_color": "Remove tag"
+    "remove_color": "Remove tag",
+    "rules": {
+      "login_changed": "You switched accounts, so the rule was not saved"
+    }
   },
   "deep_link": {
     "open_failed": "Couldn't open this"

src/api/__tests__/sieve-rules.test.ts

@@ -90,4 +90,21 @@ describe('updateAccountFilters', () => {
     await expect(updateAccountFilters(() => [rule('new')], 'own')).rejects.toBeInstanceOf(FiltersLoginChangedError);
     expect(api.createSieveScript).not.toHaveBeenCalled();
   });
+
+  // A rule made from a message and the folders of the login the sheet
+  // opened in, saved after a switch.
+  it('writes nothing into another login than the one the rule was built in', async () => {
+    api.getSieveScripts.mockResolvedValue([]);
+    const modify = vi.fn(() => [rule('new')]);
+    client.username = 'other@example.net';
+    await expect(updateAccountFilters(modify, 'own', 'me@example.org@mail.example.org'))
+      .rejects.toBeInstanceOf(FiltersLoginChangedError);
+    expect(api.getSieveScripts).not.toHaveBeenCalled();
+    expect(modify).not.toHaveBeenCalled();
+    expect(api.createSieveScript).not.toHaveBeenCalled();
+
+    client.username = 'me@example.org';
+    expect(await updateAccountFilters(modify, 'own', 'me@example.org@mail.example.org')).toBe(true);
+    expect(api.createSieveScript).toHaveBeenCalledTimes(1);
+  });
 });

src/api/sieve-rules.ts

@@ -39,14 +39,19 @@ export class FiltersLoginChangedError extends Error {
  * include, its forwarding and audience and the external rules. `modify`
  * returns null when there is nothing to write. A hand-edited script is
  * refused: it is never rewritten from a rule. Resolves to whether it wrote.
+ *
+ * `expectedLogin` is the login the rule was built in (from its message and
+ * folders); nothing is written unless the client still serves it.
  */
 export async function updateAccountFilters(
   modify: (rules: FilterRule[]) => FilterRule[] | null,
   accountId: string = getSieveAccountId(),
+  expectedLogin?: string | null,
 ): Promise<boolean> {
   // The client serves one login at a time; a switch while the script is read
   // would write these rules into the other login's account.
   const login = servedLoginOf(jmapClient);
+  if (expectedLogin !== undefined && login !== expectedLogin) throw new FiltersLoginChangedError();
   const capabilities = getSieveCapabilities(accountId);
   const all = await getSieveScripts(accountId);
   const scripts = all.filter((s) => s.name !== VACATION_SCRIPT_NAME);

src/components/filters/QuickRuleSheet.tsx

@@ -5,7 +5,9 @@ import { MoveSheet } from '../MoveSheet';
 import { FilterRuleModal } from './FilterRuleModal';
 import type { Email, Mailbox } from '../../api/types';
 import { getSieveAccountId, getSieveCapabilities } from '../../api/sieve';
-import { OpaqueFiltersError, updateAccountFilters } from '../../api/sieve-rules';
+import { FiltersLoginChangedError, OpaqueFiltersError, updateAccountFilters } from '../../api/sieve-rules';
+import { jmapClient } from '../../api/jmap-client';
+import { servedLoginOf } from '../../lib/draft-login';
 import { supportsPeriods } from '../../lib/sieve/period';
 import {
   applyQuickRule,
@@ -22,6 +24,7 @@ import {
 } from '../../lib/sieve/quick-rules';
 import type { FilterRule } from '../../lib/sieve/types';
 import { generateUUID } from '../../lib/uuid';
+import { useAccountStore } from '../../stores/account-store';
 import { useFilterStore } from '../../stores/filter-store';
 import { useKeywordsStore } from '../../stores/keywords-store';
 import { useLocaleStore } from '../../stores/locale-store';
@@ -56,9 +59,20 @@ export function QuickRuleSheet({ visible, email, mailboxes, onClose }: QuickRule
   const identities = useSettingsStore((s) => s.identities);
   const keywords = useKeywordsStore((s) => s.keywords);
   const [step, setStep] = React.useState<Step>({ kind: 'menu' });
+  // The login and Sieve account the sheet opened in. The rule is built from
+  // that login's message and folders; after a switch it must not go into the
+  // other login, where the same ids name other folders.
+  const openedIn = React.useRef<{ login: string | null; accountId: string | null }>({ login: null, accountId: null });
 
   React.useEffect(() => {
-    if (visible) setStep({ kind: 'menu' });
+    if (!visible) return;
+    setStep({ kind: 'menu' });
+    let accountId: string | null = null;
+    try { accountId = getSieveAccountId(); } catch { /* not connected yet */ }
+    // Not connected yet (a cold start), the cached message is the active
+    // login's.
+    const login = servedLoginOf(jmapClient) ?? useAccountStore.getState().activeAccountId;
+    openedIn.current = { login, accountId };
   }, [visible]);
 
   const ownAddresses = React.useMemo(
@@ -85,11 +99,17 @@ export function QuickRuleSheet({ visible, email, mailboxes, onClose }: QuickRule
 
   /** Write `modify`'s rules into the own account's script and say how it went. */
   const write = async (modify: (rules: FilterRule[]) => FilterRule[] | null) => {
-    const accountId = getSieveAccountId();
+    const { login } = openedIn.current;
+    let accountId = openedIn.current.accountId;
     try {
-      await updateAccountFilters(modify, accountId);
+      // Read now only when the sheet opened before the session was up;
+      // updateAccountFilters refuses it unless the login is still the same.
+      accountId ??= getSieveAccountId();
+      await updateAccountFilters(modify, accountId, login);
     } catch (err) {
-      if (err instanceof OpaqueFiltersError) {
+      if (err instanceof FiltersLoginChangedError) {
+        toast.error(t('context_menu.rules.login_changed', 'You switched accounts, so the rule was not saved'));
+      } else if (err instanceof OpaqueFiltersError) {
         toast.error(t('context_menu.rules.opaque_hint', 'Your filters were edited by hand. Open Filters settings'));
       } else {
         toast.error(t('notifications.filters_save_failed', 'Failed to save filters'), err instanceof Error ? err.message : undefined);