perf: deduplicate inbox search results in linear time

resources/js/lib/conversation-search.ts

@@ -15,6 +15,8 @@ export function conversationsMatching(
     const isPersonMatch = ({ handle, name }: User) =>
         isMatch(handle) || isMatch(name);
 
+    const seen = new Set<string>();
+
     return [
         ...found,
         ...onHand.filter(
@@ -26,8 +28,12 @@ export function conversationsMatching(
                     isPersonMatch(user),
                 ),
         ),
-    ].filter(
-        (conversation, index, all) =>
-            all.findIndex(({ id }) => id === conversation.id) === index,
-    );
+    ].filter(({ id }) => {
+        if (seen.has(id)) {
+            return false;
+        }
+
+        seen.add(id);
+        return true;
+    });
 }

tests/Unit/ConversationSearch.test.ts

@@ -39,3 +39,14 @@ test('keeps every conversation the server found for the term, ahead of stale cop
 
     assert.deepEqual(conversationsMatching('review', [org('core', 'Core', [ben])], found), [...found]);
 });
+
+test('deduplicates many matching server and local copies without changing their first match', () => {
+    const first = direct(ana, { ahead: 4 });
+    const duplicates = Array.from({ length: 100 }, () => direct(ana));
+    const last = org('team', 'Ana team', [ben]);
+
+    assert.deepEqual(
+        conversationsMatching('ana', [...duplicates, last], [first, first]),
+        [first, last],
+    );
+});