Take a schemeless lancedb.uri as a local path

Closes #582. `lancedb.databases` entries already classify a location by
whether it carries a scheme; `lancedb.uri` was taken as a URI whatever it
said, so a local path was opened as object storage and a mistyped one
became a new empty database instead of failing. Both settings now place a
database the same way, and `--db PATH` overrides either.

CHANGELOG.md

@@ -16,6 +16,7 @@
 - `doctor`'s docling-serve probe sends `X-Api-Key`, so an instance requiring a key is reported reachable rather than unreachable.
 - The picture-description request to the public OpenAI endpoint sends `OPENAI_API_KEY`; it carried no authorization header.
 - `haiku-rag` prints the message and exits when the configured embedder does not match the database, instead of raising a traceback.
+- A `lancedb.uri` with no scheme is a local path, as it already is in `lancedb.databases`: `haiku-rag init` creates it and every command that opens an existing database requires it to exist, where a missing path was opened as object storage and became an empty database. `--db PATH` overrides `lancedb.uri`.
 
 ## [0.77.0] - 2026-08-21
 

docs/configuration/storage.md

@@ -66,6 +66,29 @@ If that number times six exceeds available RAM, use one of:
 
 This is an upstream limitation rather than a `haiku.rag` setting. Compaction bounds itself by row count instead of bytes, and LanceDB's async API exposes no batch size or fragment target to override it. Tracked at [lancedb/lancedb#2325](https://github.com/lancedb/lancedb/issues/2325). The requirement above will drop once compaction batches by bytes.
 
+### Changing the Default Database Path
+
+`storage.data_dir` holds the default database, always called
+`haiku.rag.lancedb`. To put the database somewhere else for every command, give
+`lancedb.uri` a local path:
+
+```yaml
+lancedb:
+  uri: /data/notes.lancedb
+```
+
+An explicit `--db PATH` overrides `lancedb.uri` for that invocation.
+
+This places one database without naming it. Its `source` is `None` in search
+results, citations and documents, since only [`lancedb.databases`](#several-databases)
+assigns the names that carry provenance. A path here changes where the database
+lives, not what it is called.
+
+A value with no scheme is a local path wherever it is configured, so
+`haiku-rag init` creates it and every command that opens an existing database
+requires it to exist. A mistyped path fails rather than becoming a new empty
+database.
+
 ## Database Creation
 
 Databases must be explicitly created before use:
@@ -145,6 +168,7 @@ lancedb:
 - **LanceDB Cloud** (`db://`): Requires `api_key` and `region`. Table optimization and indexing are managed server-side.
 - **Object storage** (`s3://`, `gs://`, `az://`, `hdfs://`): Uses `storage_options` for credentials and endpoint configuration. Authentication can also be provided via environment variables (`AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`, etc.) or cloud provider SDK defaults (AWS CLI, Azure CLI, gcloud).
 - **S3-compatible stores** (MinIO, Tigris, etc.): Set `endpoint` in `storage_options`. When using `http://` endpoints, also set `allow_http: "true"`.
+- **Local path** (no scheme): `uri` also takes a local path, which is how the default database is pointed elsewhere. See [Changing the Default Database Path](#changing-the-default-database-path).
 
 The `storage_options` keys are case-insensitive and passed directly to the underlying object store library. Available keys depend on the backend. See the [LanceDB storage docs](https://lancedb.com/docs/storage/) for details.
 

haiku_rag_slim/haiku/rag/client/scope.py

@@ -42,8 +42,9 @@ class DatabaseRef:
 
     @classmethod
     def configured(cls, name: str | None, location: str) -> "DatabaseRef":
-        """A database from ``lancedb.databases``, where the configured value is a
-        URI or a local path depending on whether it carries a scheme."""
+        """A database the configuration placed, by ``lancedb.uri`` or by an entry
+        in ``lancedb.databases``. A value carrying a scheme is a URI and anything
+        else is a local path, so the two settings place a database alike."""
         uri, db_path = locate_database(location)
         return cls(name=name, uri=uri, db_path=db_path)
 
@@ -123,7 +124,7 @@ class DatabaseScope:
             )
 
         if config.lancedb.uri:
-            return cls((DatabaseRef(name=None, uri=config.lancedb.uri, db_path=None),))
+            return cls((DatabaseRef.configured(None, config.lancedb.uri),))
 
         return cls((DatabaseRef.at(config.storage.data_dir / "haiku.rag.lancedb"),))
 

tests/test_cli.py

@@ -334,6 +334,74 @@ class TestResolvingTheDatabasePath:
             resolve_scope(Path("/data/other.lancedb"))
 
 
+class TestConfiguredLocalUri:
+    """`lancedb.uri` with a local path, the surface issue #582 reports."""
+
+    def _config_file(self, tmp_path, located: Path) -> Path:
+        config_file = tmp_path / "haiku.rag.yaml"
+        config_file.write_text(f"lancedb:\n  uri: {located}\n")
+        return config_file
+
+    def _fresh(self, monkeypatch) -> None:
+        import haiku.rag.cli as cli_module
+        import haiku.rag.config as config_module
+
+        monkeypatch.setattr(config_module, "_config", None)
+        monkeypatch.setattr(cli_module, "_database", None)
+
+    def _reports(self, result, located: Path) -> bool:
+        """Rich wraps a long path to the terminal width, so compare without it."""
+        return str(located) in "".join(result.output.split())
+
+    def test_init_creates_the_configured_local_database(self, tmp_path, monkeypatch):
+        self._fresh(monkeypatch)
+        located = tmp_path / "notes.lancedb"
+        config_file = self._config_file(tmp_path, located)
+
+        result = runner.invoke(cli, ["--config", str(config_file), "init"])
+
+        assert result.exit_code == 0, result.output
+        assert located.exists()
+
+        self._fresh(monkeypatch)
+        result = runner.invoke(cli, ["--config", str(config_file), "info"])
+        assert result.exit_code == 0, result.output
+        assert self._reports(result, located)
+
+    def test_a_missing_configured_path_is_refused(self, tmp_path, monkeypatch):
+        """A schemeless value is a local path, so a typo fails instead of
+        becoming a new empty database."""
+        self._fresh(monkeypatch)
+        located = tmp_path / "typo.lancedb"
+        config_file = self._config_file(tmp_path, located)
+
+        result = runner.invoke(cli, ["--config", str(config_file), "info"])
+
+        assert "does not exist" in result.output
+        assert not located.exists()
+
+    def test_db_overrides_the_configured_uri(self, tmp_path, monkeypatch):
+        self._fresh(monkeypatch)
+        configured = tmp_path / "configured.lancedb"
+        chosen = tmp_path / "chosen.lancedb"
+        config_file = self._config_file(tmp_path, configured)
+
+        result = runner.invoke(
+            cli, ["--config", str(config_file), "init", "--db", str(chosen)]
+        )
+
+        assert result.exit_code == 0, result.output
+        assert chosen.exists()
+        assert not configured.exists()
+
+        self._fresh(monkeypatch)
+        result = runner.invoke(
+            cli, ["--config", str(config_file), "info", "--db", str(chosen)]
+        )
+        assert result.exit_code == 0, result.output
+        assert self._reports(result, chosen)
+
+
 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

tests/test_database_scope.py

@@ -74,6 +74,17 @@ class TestResolution:
 
         assert scope.databases == (DatabaseRef(None, "s3://bucket/one.lancedb", None),)
 
+    def test_a_bare_uri_without_a_scheme_is_a_local_path(self):
+        """`lancedb.uri` places one database the same way an entry in
+        `lancedb.databases` does, so a schemeless value is a path and gets the
+        existence check a local database gets."""
+        scope = DatabaseScope.resolve(_config(uri="/data/notes.lancedb"))
+
+        [ref] = scope.databases
+        assert ref.name is None
+        assert ref.db_path == Path("/data/notes.lancedb")
+        assert ref.uri == ""
+
     def test_a_path_selects_the_database_over_a_configured_uri(self):
         """`--db` exists to override what is configured, and the configuration
         derived from the ref is what makes the connection follow it."""

tests/test_multi_db.py

@@ -145,6 +145,60 @@ class TestNamingADatabaseDirectly:
         assert [r.source for r in results] == ["alpha"]
 
 
+class TestOneConfiguredLocation:
+    """`lancedb.uri` places one unnamed database, at a URI or at a local path."""
+
+    def _config(self, location) -> AppConfig:
+        return AppConfig(lancedb=LanceDBConfig(uri=str(location)))
+
+    @pytest.mark.asyncio
+    async def test_a_local_uri_opens_the_configured_database(self, tmp_path):
+        located = tmp_path / "notes.lancedb"
+        config = self._config(located)
+
+        async with HaikuRAG(config=config, create=True) as rag:
+            assert rag.store.db_path == located
+            # It places a database without naming one: only `lancedb.databases`
+            # assigns the name results and citations carry.
+            assert rag.source is None
+        assert located.exists()
+
+    @pytest.mark.asyncio
+    async def test_an_explicit_path_overrides_a_local_uri(self, tmp_path):
+        """`--db` overrides the configured location for one invocation."""
+        config = self._config(tmp_path / "configured.lancedb")
+        chosen = tmp_path / "chosen.lancedb"
+
+        async with HaikuRAG(chosen, config=config, create=True) as rag:
+            assert rag.store.db_path == chosen
+        assert chosen.exists()
+        assert not (tmp_path / "configured.lancedb").exists()
+
+    @pytest.mark.asyncio
+    async def test_a_local_uri_that_does_not_exist_is_refused(self, tmp_path):
+        """A mistyped path fails instead of quietly becoming an empty database,
+        which is what a value carrying a scheme would do."""
+        config = self._config(tmp_path / "typo.lancedb")
+
+        with pytest.raises(FileNotFoundError):
+            async with HaikuRAG(config=config):
+                pass
+        assert not (tmp_path / "typo.lancedb").exists()
+
+    def test_a_uri_with_a_scheme_stays_a_uri(self, tmp_path):
+        """Object storage has no local path to check, and a location that does
+        not exist yet is normal there."""
+        from haiku.rag.store.engine import ConnectionMode
+
+        config = self._config("s3://bucket/one.lancedb")
+
+        [ref] = DatabaseScope.resolve(config).databases
+        one, db_path = ref.connection(config)
+
+        assert db_path is None
+        assert ConnectionMode.from_config(one) == ConnectionMode.OBJECT_STORAGE
+
+
 class TestOpeningDatabases:
     @pytest.mark.asyncio
     async def test_missing_databases_open_together(self, tmp_path):