Move ConfigMismatchError to the store exceptions module

The CLI reports this error, and importing it from the settings repository
pulled lancedb onto the CLI's import path. Deferring the import into cli()
bought nothing, since cli() runs on every invocation: it cost about 1.9
seconds on a cold start, `--help` included.

It now sits beside the other store exceptions, in a module that imports
nothing, and every importer points there.

haiku_rag_slim/haiku/rag/cli.py

@@ -23,6 +23,7 @@ from haiku.rag.config import (  # noqa: E402
 from haiku.rag.logging import configure_cli_logging  # noqa: E402
 from haiku.rag.store.exceptions import (  # noqa: E402
     AmbiguousDatabaseError,
+    ConfigMismatchError,
     MigrationRequiredError,
     ReadOnlyError,
     SourceUnavailableError,
@@ -42,10 +43,6 @@ _cli = typer.Typer(
 
 
 def cli():
-    # Imported here rather than at module scope: the settings module pulls in
-    # lancedb, and the CLI's startup must not pay for it.
-    from haiku.rag.store.repositories.settings import ConfigMismatchError
-
     try:
         _cli()
     except (

haiku_rag_slim/haiku/rag/client/__init__.py

@@ -20,6 +20,7 @@ from haiku.rag.converters import get_converter
 from haiku.rag.reranking import get_reranker
 from haiku.rag.store.engine import Store
 from haiku.rag.store.exceptions import (
+    ConfigMismatchError,
     MigrationRequiredError,
     ReadOnlyError,
     SourceUnavailableError,
@@ -30,10 +31,7 @@ from haiku.rag.store.models.document_item import extract_items
 from haiku.rag.store.repositories.chunk import ChunkRepository
 from haiku.rag.store.repositories.document import DocumentRepository
 from haiku.rag.store.repositories.document_item import DocumentItemRepository
-from haiku.rag.store.repositories.settings import (
-    ConfigMismatchError,
-    SettingsRepository,
-)
+from haiku.rag.store.repositories.settings import SettingsRepository
 from haiku.rag.utils import escape_sql_string, locate_database
 
 if TYPE_CHECKING:

haiku_rag_slim/haiku/rag/client/rebuild.py

@@ -161,7 +161,7 @@ async def _set_embedder(client: "HaikuRAG") -> None:
     usable, so just the recorded provider/name are updated. A changed dimension
     requires regenerating every embedding via a full rebuild.
     """
-    from haiku.rag.store.repositories.settings import ConfigMismatchError
+    from haiku.rag.store.exceptions import ConfigMismatchError
 
     settings_repo = SettingsRepository(client.store)
     stored = await settings_repo.get_current_settings()

haiku_rag_slim/haiku/rag/store/__init__.py

@@ -1,5 +1,6 @@
 from .exceptions import (
     AmbiguousDatabaseError,
+    ConfigMismatchError,
     MigrationRequiredError,
     ReadOnlyError,
     SourceUnavailableError,
@@ -12,5 +13,6 @@ __all__ = [
     "MigrationRequiredError",
     "ReadOnlyError",
     "AmbiguousDatabaseError",
+    "ConfigMismatchError",
     "SourceUnavailableError",
 ]

haiku_rag_slim/haiku/rag/store/exceptions.py

@@ -4,6 +4,12 @@ class ReadOnlyError(Exception):
     pass
 
 
+class ConfigMismatchError(Exception):
+    """Raised when stored config doesn't match current config."""
+
+    pass
+
+
 class MigrationRequiredError(Exception):
     """Database requires migration. Run 'haiku-rag migrate' to upgrade."""
 

haiku_rag_slim/haiku/rag/store/repositories/settings.py

@@ -2,17 +2,12 @@ import json
 import logging
 
 from haiku.rag.store.engine import Store
+from haiku.rag.store.exceptions import ConfigMismatchError
 from haiku.rag.store.schema import SettingsRecord, query_to_pydantic
 
 logger = logging.getLogger(__name__)
 
 
-class ConfigMismatchError(Exception):
-    """Raised when stored config doesn't match current config."""
-
-    pass
-
-
 class SettingsRepository:
     """Repository for Settings operations."""
 

tests/store/test_read_only.py

@@ -394,7 +394,7 @@ class TestAppReadVerbsDoNotWrite:
         """A write CLI verb opens writable: drift raises before any write."""
         from haiku.rag.app import HaikuRAGApp
         from haiku.rag.config import AppConfig
-        from haiku.rag.store.repositories.settings import ConfigMismatchError
+        from haiku.rag.store.exceptions import ConfigMismatchError
 
         async with Store(temp_db_path, create=True) as store:
             stored_name_before = (

tests/test_cli.py

@@ -332,7 +332,7 @@ class TestCliConfigMismatchError:
     def test_a_config_mismatch_exits_with_its_remedy(self):
         """The message says which database and what to run, so it is worth more
         than a traceback."""
-        from haiku.rag.store.repositories.settings import ConfigMismatchError
+        from haiku.rag.store.exceptions import ConfigMismatchError
 
         with patch("haiku.rag.cli._cli") as mock_cli:
             mock_cli.side_effect = ConfigMismatchError(

tests/test_mcp.py

@@ -645,7 +645,7 @@ class TestMCPClientLifetime:
         read-only mode and raises in writable mode. The MCP server no longer
         opts out of it for deletion."""
         from haiku.rag.config import get_config
-        from haiku.rag.store.repositories.settings import ConfigMismatchError
+        from haiku.rag.store.exceptions import ConfigMismatchError
 
         drifted = get_config().model_copy(deep=True)
         drifted.embeddings.model.name = "a-different-model"

tests/test_rebuild.py

@@ -1059,7 +1059,7 @@ async def test_rebuild_set_embedder_works_on_empty_database(temp_db_path):
 async def test_rebuild_set_embedder_raises_on_vector_dim_mismatch(temp_db_path):
     """SET_EMBEDDER refuses when the vector dimension changed — a full rebuild is needed."""
     from haiku.rag.config import AppConfig
-    from haiku.rag.store.repositories.settings import ConfigMismatchError
+    from haiku.rag.store.exceptions import ConfigMismatchError
 
     async with HaikuRAG(temp_db_path, create=True):
         pass

tests/test_settings.py

@@ -3,7 +3,7 @@ import logging
 import pytest
 
 from haiku.rag.config import AppConfig, get_config
-from haiku.rag.store.repositories.settings import ConfigMismatchError
+from haiku.rag.store.exceptions import ConfigMismatchError
 
 
 @pytest.mark.asyncio