Coerce a string db_path to Path at the Store and capability boundaries

The documented `HaikuRAG("knowledge.lancedb")` and `rag(db_path="my.lancedb")`
forms both raised `AttributeError: 'str' object has no attribute 'exists'`.
`Store.__init__` assigned its argument to a `Path`-annotated attribute without
coercing, and `resolve_db_path` returned a non-None argument unchanged. Every
runnable example wraps the path in `Path(...)`, which is why it survived.

Coerce in `Store.__init__` and `resolve_db_path`; widen the annotations on
`Store`, `HaikuRAG` and both `create_capability` factories to accept `str`.

CHANGELOG.md

@@ -3,6 +3,8 @@
 
 ### Fixed
 
+- `Store`, `HaikuRAG` and `create_capability` coerce a string `db_path` to `Path`, as the documented
+  `HaikuRAG("knowledge.lancedb")` and `rag(db_path="my.lancedb")` forms require.
 - A capability search that matches nothing returns `No results found.` instead of an empty string.
 - Repeating a search query within a question accumulates the results of both calls instead of replacing the earlier ones.
 - `file://` URIs resolve to a Windows path through `url2pathname`: `file:///C:/docs/a.pdf` was read as `\C:\docs\a.pdf`, so ingestion reported `File does not exist` for every discovered file. A URI authority is kept as a UNC server/share (`file://server/share/a.pdf`) except `localhost`, which is dropped.

haiku_rag_slim/haiku/rag/capabilities/_base.py

@@ -70,9 +70,9 @@ def _nearest_known_id(chunk_id: str, known_ids: list[str]) -> str:
     return match[0] if match else chunk_id
 
 
-def resolve_db_path(db_path: Path | None, config: AppConfig) -> Path:
+def resolve_db_path(db_path: Path | str | None, config: AppConfig) -> Path:
     if db_path is not None:
-        return db_path
+        return Path(db_path)
     if env_db := os.environ.get("HAIKU_RAG_DB"):
         return Path(env_db).expanduser()
     return config.storage.data_dir / "haiku.rag.lancedb"

haiku_rag_slim/haiku/rag/capabilities/analysis.py

@@ -156,7 +156,7 @@ class AnalysisCapability(RAGCapabilityBase[AnalysisState]):
 
 
 def create_capability(
-    db_path: Path | None = None,
+    db_path: Path | str | None = None,
     config: AppConfig | None = None,
     *,
     defer_loading: bool = True,

haiku_rag_slim/haiku/rag/capabilities/rag.py

@@ -64,7 +64,7 @@ class RAGCapability(RAGCapabilityBase[RAGState]):
 
 
 def create_capability(
-    db_path: Path | None = None,
+    db_path: Path | str | None = None,
     config: AppConfig | None = None,
     *,
     defer_loading: bool = True,

haiku_rag_slim/haiku/rag/client/__init__.py

@@ -66,7 +66,7 @@ class HaikuRAG:
 
     def __init__(
         self,
-        db_path: Path | None = None,
+        db_path: Path | str | None = None,
         config: AppConfig | None = None,
         skip_validation: bool = False,
         create: bool = False,
@@ -75,7 +75,8 @@ class HaikuRAG:
         """Initialize the RAG client with a database path.
 
         Args:
-            db_path: Path to the database file. If None, uses config.storage.data_dir.
+            db_path: Path or string path to the database file. If None, uses
+                config.storage.data_dir.
             config: Configuration to use. Defaults to the current global config.
             skip_validation: Whether to skip configuration validation on database load.
             create: Whether to create the database if it doesn't exist.

haiku_rag_slim/haiku/rag/store/engine.py

@@ -170,14 +170,14 @@ class TagInfo:
 class Store:
     def __init__(
         self,
-        db_path: Path,
+        db_path: Path | str,
         config: AppConfig | None = None,
         skip_validation: bool = False,
         create: bool = False,
         read_only: bool = False,
         skip_migration_check: bool = False,
     ):
-        self.db_path: Path = db_path
+        self.db_path: Path = Path(db_path)
         self._config = config if config is not None else get_config()
         self._read_only = read_only
         self._create = create
@@ -191,7 +191,7 @@ class Store:
         self._is_new_db = False
 
         if self._connection_mode == ConnectionMode.LOCAL:
-            if not db_path.exists():
+            if not self.db_path.exists():
                 if not create:
                     raise FileNotFoundError(
                         f"Database does not exist at {self.db_path.absolute()}. "
@@ -199,8 +199,8 @@ class Store:
                     )
                 self._is_new_db = True
                 # Ensure parent directories exist for new databases
-                if not db_path.parent.exists():
-                    Path.mkdir(db_path.parent, parents=True)
+                if not self.db_path.parent.exists():
+                    Path.mkdir(self.db_path.parent, parents=True)
 
         # Create embedder (sync — no LanceDB needed)
         self.embedder = get_embedder(config=self._config)

tests/capabilities/test_capabilities.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass, field
+from pathlib import Path
 from types import SimpleNamespace
 from typing import Any, cast
 from unittest.mock import AsyncMock, patch
@@ -102,11 +103,33 @@ def test_capability_factories_resolve_environment_and_defaults(
         config.storage.data_dir / "haiku.rag.lancedb"
     )
 
+    for factory in (create_rag, create_analysis):
+        db_path = factory(db_path=str(temp_db_path), config=config).db_path
+        assert db_path == temp_db_path
+        assert isinstance(db_path, Path)
+
     with patch("haiku.rag.config.get_config", return_value=config):
         assert create_rag().config is config
         assert create_analysis().config is config
 
 
+@pytest.mark.asyncio
+async def test_a_string_db_path_opens_a_store(temp_db_path):
+    """Store calls `absolute()` and `exists()` on db_path, which a str lacks."""
+    from haiku.rag.client import HaikuRAG
+
+    config = AppConfig()
+    async with HaikuRAG(temp_db_path, config, create=True):
+        pass
+
+    capability = create_rag(db_path=str(temp_db_path), config=config)
+    try:
+        rag = await capability._ensure_rag()
+        assert rag.store.db_path == temp_db_path
+    finally:
+        await capability._close()
+
+
 def test_domain_preamble_is_added_to_capability_instructions(temp_db_path):
     config = AppConfig(
         prompts=PromptsConfig(domain_preamble="The corpus contains solar manuals.")

tests/test_client.py

@@ -30,6 +30,15 @@ def vcr_cassette_dir():
     return str(Path(__file__).parent / "cassettes" / "test_client")
 
 
+@pytest.mark.asyncio
+async def test_a_string_db_path_is_accepted(temp_db_path):
+    """The documented `HaikuRAG("knowledge.lancedb")` form: Store calls
+    `exists()` and `absolute()` on db_path, which a str lacks."""
+    async with HaikuRAG(str(temp_db_path), create=True) as client:
+        assert client.store.db_path == temp_db_path
+        assert isinstance(client.store.db_path, Path)
+
+
 @pytest.mark.asyncio
 async def test_prepare_document_from_docling_runs_off_event_loop_thread(monkeypatch):
     import haiku.rag.client.documents as documents