feat(notion-search): add SHA256-keyed JSON file cache

Cache layer for rerank results. Key is SHA256 of query + sorted
candidate IDs, so changing the candidate set automatically invalidates.
1-day TTL by default; corrupted cache files are silently dropped.

5 tests cover hit, miss, different-candidates, TTL expiry, corruption.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

custom-skills/31-notion-organizer/code/scripts/test_notion_search.py

@@ -58,11 +58,80 @@ def test_call_claude_raises_when_neither_available():
                     "error mentions setup options")
 
 
+def test_cache_miss_returns_none():
+    import tempfile
+    from pathlib import Path
+    import _search_cache
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        result = _search_cache.cache_get("query", ["id1", "id2"], cache_dir=Path(tmpdir))
+        _assert(result is None, "cache miss returns None")
+
+
+def test_cache_hit_returns_cached_results():
+    import tempfile
+    from pathlib import Path
+    import _search_cache
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cache_dir = Path(tmpdir)
+        results = [{"id": "abc", "title": "Test"}]
+        _search_cache.cache_put("query", ["id1", "id2"], results, cache_dir=cache_dir)
+        hit = _search_cache.cache_get("query", ["id1", "id2"], cache_dir=cache_dir)
+        _assert(hit == results, "cache hit returns the stored results")
+
+
+def test_cache_miss_on_different_candidates():
+    import tempfile
+    from pathlib import Path
+    import _search_cache
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cache_dir = Path(tmpdir)
+        _search_cache.cache_put("query", ["id1", "id2"], [{"x": 1}], cache_dir=cache_dir)
+        miss = _search_cache.cache_get("query", ["id1", "id3"], cache_dir=cache_dir)
+        _assert(miss is None, "different candidate set hashes to different key")
+
+
+def test_cache_miss_after_ttl_expires():
+    import tempfile
+    from pathlib import Path
+    import _search_cache
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cache_dir = Path(tmpdir)
+        _search_cache.cache_put("query", ["id1"], [{"x": 1}], cache_dir=cache_dir)
+        # TTL=0 means immediately expired
+        miss = _search_cache.cache_get("query", ["id1"], cache_dir=cache_dir, ttl_seconds=0)
+        _assert(miss is None, "expired cache returns None")
+
+
+def test_cache_handles_corrupted_file():
+    import tempfile
+    import hashlib
+    from pathlib import Path
+    import _search_cache
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cache_dir = Path(tmpdir)
+        cache_dir.mkdir(exist_ok=True)
+        # Write garbage to the expected key path
+        key = hashlib.sha256("query|id1".encode()).hexdigest()
+        (cache_dir / f"{key}.json").write_text("not json {{{")
+        result = _search_cache.cache_get("query", ["id1"], cache_dir=cache_dir)
+        _assert(result is None, "corrupted cache file returns None")
+
+
 def run_all():
     tests = [
         test_call_claude_dispatches_to_sdk_when_available,
         test_call_claude_falls_back_to_cli_when_no_sdk,
         test_call_claude_raises_when_neither_available,
+        test_cache_miss_returns_none,
+        test_cache_hit_returns_cached_results,
+        test_cache_miss_on_different_candidates,
+        test_cache_miss_after_ttl_expires,
+        test_cache_handles_corrupted_file,
     ]
     for t in tests:
         print(f"\n{t.__name__}")