fix(logout): clear the call-volume list and settings-sync stamp (#347)

Logout left lotus-per-user-volume (Element Call's per-person volume map:
whom the previous user called and turned up/down; same origin on the web)
and settings-sync-meta:<userId> (a key naming the account) in
localStorage. clearPlaintextCaches now removes both; device preferences
(`settings`) are kept as before.

Verified: after joining/leaving a call and logging out via Settings, both
keys are gone (unit test added).

Fixes #347

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/state/plaintextCaches.test.ts

@@ -83,3 +83,14 @@ test('clearPlaintextCaches wipes drafts (#41) and the status message (#204) but
   assert.ok(!removed.includes('cinny_session'), 'session key not this module’s concern');
   assert.ok(store.has('cinny_session'));
 });
+
+test('clearPlaintextCaches removes the call-volume list and the settings-sync stamp (#347)', () => {
+  store.clear();
+  store.set('lotus-per-user-volume', '{"@bob:server":0.3}');
+  store.set('settings-sync-meta:@me:server', '{"lastSyncedAt":1}');
+  store.set('settings', '{}');
+  clearPlaintextCaches('@me:server');
+  assert.equal(store.has('lotus-per-user-volume'), false);
+  assert.equal(store.has('settings-sync-meta:@me:server'), false);
+  assert.equal(store.has('settings'), true, 'device preferences are kept');
+});

src/app/state/plaintextCaches.ts

@@ -47,6 +47,8 @@ const clearMsgDrafts = (): void => {
  * - `cinny_recent_gifs_v1` / `cinny_recent_stickers_v1` — media the user sent
  * - `navToActivePath<userId>` — per-space last-visited room paths (needs userId)
  * - `lotus_outbox_v1` — decrypted content of messages not yet sent ([Gitea #112])
+ * - `lotus-per-user-volume`, `settings-sync-meta:<userId>` — whom you adjusted in
+ *   calls, and a key naming the account ([Gitea #347])
  * - `draft-msg-*` — unsent composer drafts (decrypted message text, unscoped by
  *   user — see [Gitea #41]; previously deliberately preserved across logout
  *   (N98), which let the next account on this device see/send a prior user's
@@ -92,6 +94,24 @@ const clearStatusMessage = (): void => {
   });
 };
 
+/**
+ * [Gitea #347] Per-person residue that isn't message text but still says whom
+ * the previous user dealt with: Element Call's per-user volume memory (same
+ * origin on the web — element-call `lotusVolumeMemory.ts`) and the settings-sync
+ * stamp, whose key names the account.
+ */
+export const CALL_VOLUME_KEY = 'lotus-per-user-volume';
+const clearCallVolumesAndSyncMeta = (userId?: string): void => {
+  const keys = [CALL_VOLUME_KEY, ...(userId ? [`settings-sync-meta:${userId}`] : [])];
+  keys.forEach((key) => {
+    try {
+      localStorage.removeItem(key);
+    } catch {
+      // best-effort
+    }
+  });
+};
+
 export const clearPlaintextCaches = (userId?: string): void => {
   clearTranslationCache();
   clearScheduledMessages();
@@ -103,5 +123,6 @@ export const clearPlaintextCaches = (userId?: string): void => {
   clearOutbox();
   clearCallSession();
   clearStatusMessage();
+  clearCallVolumesAndSyncMeta(userId);
   if (userId) clearNavToActivePathStore(userId);
 };