feat(core): add default_search_type config setting (#676)

Signed-off-by: phernandez <paul@basicmachines.co>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: phernandez

src/basic_memory/config.py

@@ -203,6 +203,12 @@ class BasicMemoryConfig(BaseSettings):
         ge=0.0,
         le=1.0,
     )
+    default_search_type: Literal["text", "vector", "hybrid"] | None = Field(
+        default=None,
+        description="Default search type for search_notes when not specified per-query. "
+        "Valid values: text, vector, hybrid. "
+        "When unset, defaults to 'hybrid' if semantic search is enabled, otherwise 'text'.",
+    )
 
     # Database connection pool configuration (Postgres only)
     db_pool_size: int = Field(

src/basic_memory/mcp/tools/search.py

@@ -25,20 +25,20 @@
 )
 
 
-def _semantic_search_enabled_for_text_search() -> bool:
-    """Resolve semantic-search enablement in both MCP and CLI invocation paths."""
+def _default_search_type() -> str:
+    """Pick default search mode from config, falling back to auto-detection.
+
+    Priority: config default_search_type > auto-detect (hybrid if semantic enabled, else text).
+    """
     try:
-        return get_container().config.semantic_search_enabled
+        config = get_container().config
     except RuntimeError:
-        # Trigger: MCP container is not initialized (e.g., `bm tool search-notes` direct call).
-        # Why: CLI path still needs the same semantic-default behavior as MCP server path.
-        # Outcome: load config directly and keep text-mode retrieval behavior consistent.
-        return ConfigManager().config.semantic_search_enabled
+        config = ConfigManager().config
 
+    if config.default_search_type:
+        return config.default_search_type
 
-def _default_search_type() -> str:
-    """Pick default search mode from semantic-search config."""
-    return "hybrid" if _semantic_search_enabled_for_text_search() else "text"
+    return "hybrid" if config.semantic_search_enabled else "text"
 
 
 def _format_search_error_response(

tests/mcp/test_tool_search.py

@@ -788,6 +788,7 @@ async def search(self, payload, page, page_size):
     @dataclass
     class StubConfig:
         semantic_search_enabled: bool = True
+        default_search_type: str | None = None
 
     @dataclass
     class StubContainer:
@@ -849,6 +850,7 @@ async def search(self, payload, page, page_size):
     @dataclass
     class StubConfig:
         semantic_search_enabled: bool = False
+        default_search_type: str | None = None
 
     @dataclass
     class StubContainer:
@@ -909,6 +911,7 @@ async def search(self, payload, page, page_size):
     @dataclass
     class StubConfig:
         semantic_search_enabled: bool = True
+        default_search_type: str | None = None
 
     @dataclass
     class StubContainer:
@@ -976,7 +979,11 @@ def raise_runtime_error():
         lambda: type(
             "StubConfigManager",
             (),
-            {"config": type("Cfg", (), {"semantic_search_enabled": True})()},
+            {
+                "config": type(
+                    "Cfg", (), {"semantic_search_enabled": True, "default_search_type": None}
+                )()
+            },
         )(),
     )
 
@@ -1037,7 +1044,11 @@ def raise_runtime_error():
         lambda: type(
             "StubConfigManager",
             (),
-            {"config": type("Cfg", (), {"semantic_search_enabled": False})()},
+            {
+                "config": type(
+                    "Cfg", (), {"semantic_search_enabled": False, "default_search_type": None}
+                )()
+            },
         )(),
     )
 
@@ -1567,3 +1578,54 @@ async def search(self, payload, page, page_size):
 
     # "note_type" aliased to "type", "priority" passes through unchanged
     assert captured_payload["metadata_filters"] == {"type": "spec", "priority": "high"}
+
+
+def test_default_search_type_uses_config_value():
+    """_default_search_type should return config.default_search_type when set."""
+    import sys
+    from unittest.mock import MagicMock, patch
+
+    search_module = sys.modules["basic_memory.mcp.tools.search"]
+
+    mock_config = MagicMock()
+    mock_config.default_search_type = "vector"
+    mock_config.semantic_search_enabled = True
+    mock_container = MagicMock()
+    mock_container.config = mock_config
+
+    with patch.object(search_module, "get_container", return_value=mock_container):
+        assert search_module._default_search_type() == "vector"
+
+
+def test_default_search_type_falls_back_to_hybrid_when_semantic_enabled():
+    """When default_search_type is None and semantic is enabled, default to hybrid."""
+    import sys
+    from unittest.mock import MagicMock, patch
+
+    search_module = sys.modules["basic_memory.mcp.tools.search"]
+
+    mock_config = MagicMock()
+    mock_config.default_search_type = None
+    mock_config.semantic_search_enabled = True
+    mock_container = MagicMock()
+    mock_container.config = mock_config
+
+    with patch.object(search_module, "get_container", return_value=mock_container):
+        assert search_module._default_search_type() == "hybrid"
+
+
+def test_default_search_type_falls_back_to_text_when_semantic_disabled():
+    """When default_search_type is None and semantic is disabled, default to text."""
+    import sys
+    from unittest.mock import MagicMock, patch
+
+    search_module = sys.modules["basic_memory.mcp.tools.search"]
+
+    mock_config = MagicMock()
+    mock_config.default_search_type = None
+    mock_config.semantic_search_enabled = False
+    mock_container = MagicMock()
+    mock_container.config = mock_config
+
+    with patch.object(search_module, "get_container", return_value=mock_container):
+        assert search_module._default_search_type() == "text"

tests/test_config.py

@@ -903,6 +903,22 @@ def test_semantic_min_similarity_bounds_validation(self):
         with pytest.raises(Exception):
             BasicMemoryConfig(semantic_min_similarity=1.1)
 
+    def test_default_search_type_defaults_to_none(self):
+        """default_search_type should be None by default (auto-detect)."""
+        config = BasicMemoryConfig()
+        assert config.default_search_type is None
+
+    def test_default_search_type_accepts_valid_values(self):
+        """default_search_type accepts text, vector, hybrid."""
+        for search_type in ("text", "vector", "hybrid"):
+            config = BasicMemoryConfig(default_search_type=search_type)
+            assert config.default_search_type == search_type
+
+    def test_default_search_type_rejects_invalid_values(self):
+        """default_search_type rejects unknown values."""
+        with pytest.raises(Exception):
+            BasicMemoryConfig(default_search_type="invalid")
+
 
 class TestFormattingConfig:
     """Test file formatting configuration options."""