added proper cache invalidation to load_bm25_corpus

tests/test_ebook_search_ui.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 from fastapi.testclient import TestClient
 from sqlalchemy import create_engine
 
+from python.ebook_search.api.bm25_tasks import refresh_bm25_for_engine
 from python.ebook_search.api.main import create_app
 from python.ebook_search.config import EbookSearchConfig, RerankConfig
 from python.ebook_search.embeddings import EmbeddingModelStats
@@ -232,6 +233,29 @@ def test_ui_scan_schedules_bm25_refresh_after_database_change(monkeypatch) -> No
     assert scheduled is True
 
 
+def test_bm25_refresh_clears_loaded_corpus_cache(monkeypatch) -> None:
+    refreshed: list[object] = []
+    cache_cleared = False
+
+    def fake_refresh_bm25_corpus(session, config):
+        refreshed.append((session, config))
+
+    def fake_cache_clear():
+        nonlocal cache_cleared
+        cache_cleared = True
+
+    monkeypatch.setattr("python.ebook_search.api.bm25_tasks.refresh_bm25_corpus", fake_refresh_bm25_corpus)
+    monkeypatch.setattr("python.ebook_search.api.bm25_tasks.load_bm25_corpus.cache_clear", fake_cache_clear)
+    engine = create_engine("sqlite+pysqlite:///:memory:", future=True)
+    config = EbookSearchConfig(rerank=RerankConfig(enabled=False))
+
+    refresh_bm25_for_engine(engine, config)
+
+    assert len(refreshed) == 1
+    assert refreshed[0][1] == config
+    assert cache_cleared is True
+
+
 def test_admin_page_shows_embedding_counts_by_model(monkeypatch) -> None:
     def fake_embedding_model_stats(_session):
         return [