test: expand coverage to 70%, fix mcp_server CI crash (threshold 60%)

Add/expand tests for normalize (39%→97%), searcher (39%→100%),
layers (28%→97%), split_mega_files (34%→72%).

Fix mcp_server.py parse_args→parse_known_args to prevent SystemExit
when imported during pytest (CI was crashing on all test jobs).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_searcher.py

@@ -1,10 +1,18 @@
 """
-test_searcher.py — Tests for the programmatic search_memories API.
+test_searcher.py -- Tests for both search() (CLI) and search_memories() (API).
 
-Tests the library-facing search interface (not the CLI print variant).
+Uses the real ChromaDB fixtures from conftest.py for integration tests,
+plus mock-based tests for error paths.
 """
 
-from mempalace.searcher import search_memories
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from mempalace.searcher import SearchError, search, search_memories
+
+
+# ── search_memories (API) ──────────────────────────────────────────────
 
 
 class TestSearchMemories:
@@ -43,3 +51,75 @@ class TestSearchMemories:
         assert "source_file" in hit
         assert "similarity" in hit
         assert isinstance(hit["similarity"], float)
+
+    def test_search_memories_query_error(self):
+        """search_memories returns error dict when query raises."""
+        mock_col = MagicMock()
+        mock_col.query.side_effect = RuntimeError("query failed")
+        mock_client = MagicMock()
+        mock_client.get_collection.return_value = mock_col
+
+        with patch("mempalace.searcher.chromadb.PersistentClient", return_value=mock_client):
+            result = search_memories("test", "/fake/path")
+        assert "error" in result
+        assert "query failed" in result["error"]
+
+    def test_search_memories_filters_in_result(self, palace_path, seeded_collection):
+        result = search_memories("test", palace_path, wing="project", room="backend")
+        assert result["filters"]["wing"] == "project"
+        assert result["filters"]["room"] == "backend"
+
+
+# ── search() (CLI print function) ─────────────────────────────────────
+
+
+class TestSearchCLI:
+    def test_search_prints_results(self, palace_path, seeded_collection, capsys):
+        search("JWT authentication", palace_path)
+        captured = capsys.readouterr()
+        assert "JWT" in captured.out or "authentication" in captured.out
+
+    def test_search_with_wing_filter(self, palace_path, seeded_collection, capsys):
+        search("planning", palace_path, wing="notes")
+        captured = capsys.readouterr()
+        assert "Results for" in captured.out
+
+    def test_search_with_room_filter(self, palace_path, seeded_collection, capsys):
+        search("database", palace_path, room="backend")
+        captured = capsys.readouterr()
+        assert "Room:" in captured.out
+
+    def test_search_with_wing_and_room(self, palace_path, seeded_collection, capsys):
+        search("code", palace_path, wing="project", room="frontend")
+        captured = capsys.readouterr()
+        assert "Wing:" in captured.out
+        assert "Room:" in captured.out
+
+    def test_search_no_palace_raises(self, tmp_path):
+        with pytest.raises(SearchError, match="No palace found"):
+            search("anything", str(tmp_path / "missing"))
+
+    def test_search_no_results(self, palace_path, collection, capsys):
+        """Empty collection returns no results message."""
+        # collection is empty (no seeded data)
+        result = search("xyzzy_nonexistent_query", palace_path, n_results=1)
+        captured = capsys.readouterr()
+        # Either prints "No results" or returns None
+        assert result is None or "No results" in captured.out
+
+    def test_search_query_error_raises(self):
+        """search raises SearchError when query fails."""
+        mock_col = MagicMock()
+        mock_col.query.side_effect = RuntimeError("boom")
+        mock_client = MagicMock()
+        mock_client.get_collection.return_value = mock_col
+
+        with patch("mempalace.searcher.chromadb.PersistentClient", return_value=mock_client):
+            with pytest.raises(SearchError, match="Search error"):
+                search("test", "/fake/path")
+
+    def test_search_n_results(self, palace_path, seeded_collection, capsys):
+        search("code", palace_path, n_results=1)
+        captured = capsys.readouterr()
+        # Should have output with at least one result block
+        assert "[1]" in captured.out