perf: search.py N+1 batching + k constant extraction (T106)

tests/test_search_ux.py

@@ -16,6 +16,7 @@ Verifies the FastAPI ``/search`` route that wraps T93's
 from __future__ import annotations
 
 from pathlib import Path
+from unittest.mock import patch
 
 import pytest
 from fastapi.testclient import TestClient
@@ -133,3 +134,30 @@ def test_result_links_navigate_to_chat(client, tmp_path):
     # The link target is chat-level (memories don't carry an event_id
     # column today, so we don't deep-link to a specific turn).
     assert 'href="/chats/chat_a"' in resp.text
+
+
+def test_search_results_use_batched_lookups(client, tmp_path):
+    """T106: hydration must not fan out to per-row ``get_bot``/
+    ``get_chat``/``get_scene`` calls.
+
+    The previous implementation called each helper once per result row
+    (worst case 50 rows x 3 helpers = 150 individual queries). The
+    batched implementation collects distinct ids and issues at most one
+    query per entity kind via ``WHERE id IN (...)``, so the per-row
+    helpers should not be invoked at all when there are matches.
+
+    We seed two chats (so both ``get_bot`` and ``get_chat`` would have
+    been hit pre-T106) and assert each helper sees zero per-row calls.
+    """
+    _seed_two_chats_with_memories(tmp_path / "test.db")
+    with (
+        patch("chat.web.search.get_bot") as mock_get_bot,
+        patch("chat.web.search.get_chat") as mock_get_chat,
+        patch("chat.web.search.get_scene") as mock_get_scene,
+    ):
+        resp = client.get("/search?q=rabbit")
+    assert resp.status_code == 200
+    # Batched IN-list queries replace the per-row helpers entirely.
+    assert mock_get_bot.call_count == 0
+    assert mock_get_chat.call_count == 0
+    assert mock_get_scene.call_count == 0