perf(notifications): memoize getNotificationType per push-rules object and room

Fixes #77

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/utils/room.test.ts

@@ -24,6 +24,7 @@ import {
   getOrphanParents,
   isMutedRule,
   findMutedRule,
+  getNotificationType,
   isNotificationEvent,
   isVerificationFlowEvent,
   unreadIsOnlyVerification,
@@ -46,7 +47,7 @@ import {
   getMentionContent,
   getAllVersionsRoomCreator,
 } from './room';
-import { RoomType, StateEvent, RoomToParents } from '../../types/matrix/room';
+import { RoomType, StateEvent, RoomToParents, NotificationType } from '../../types/matrix/room';
 
 // --- Mock helpers ---------------------------------------------------------
 
@@ -341,6 +342,43 @@ test('findMutedRule finds rule by id that is also muted', () => {
   assert.equal(findMutedRule(rules, '!missing'), undefined);
 });
 
+// --- getNotificationType (memoization, #77) -------------------------------
+
+test('getNotificationType memoizes per push-rules content object and room id', () => {
+  let scanCalls = 0;
+  const overrideRules = [{ rule_id: '!muted', actions: [], conditions: [{ kind: 'event_match' }] }];
+  const pushRulesContent = { global: { override: overrideRules } };
+  const mx = {
+    getRoomPushRule: () => {
+      scanCalls += 1;
+      return undefined;
+    },
+    getAccountData: () => ({ getContent: () => pushRulesContent }),
+  } as never;
+
+  assert.equal(getNotificationType(mx, '!muted'), NotificationType.Mute);
+  assert.equal(getNotificationType(mx, '!muted'), NotificationType.Mute);
+  assert.equal(getNotificationType(mx, '!muted'), NotificationType.Mute);
+  // Repeated calls with the same (content object, roomId) pair must hit the
+  // cache instead of re-running getRoomPushRule + the override scan.
+  assert.equal(scanCalls, 1);
+
+  // A different room id under the same push-rules content is a separate cache
+  // entry and still gets computed.
+  assert.equal(getNotificationType(mx, '!other'), NotificationType.Default);
+  assert.equal(scanCalls, 2);
+
+  // A new push-rules content object (simulating an `m.push_rules` account-data
+  // update) invalidates the cache and forces a recompute.
+  const newContent = { global: { override: overrideRules } };
+  const mx2 = {
+    getRoomPushRule: mx.getRoomPushRule,
+    getAccountData: () => ({ getContent: () => newContent }),
+  } as never;
+  assert.equal(getNotificationType(mx2, '!muted'), NotificationType.Mute);
+  assert.equal(scanCalls, 3);
+});
+
 // --- isNotificationEvent --------------------------------------------------
 
 test('isNotificationEvent accepts message/sticker but rejects member, redacted, edits', () => {