Report a stemless --db path as a usage error and separate the two lancedb.uri migrations

An empty lancedb.uri, which init-config used to emit, is told to remove the
key; only a non-empty value is told the databases spelling. haiku-rag --db
and haiku-ingester --db turn a path with no stem into typer.BadParameter.

CHANGELOG.md

@@ -24,7 +24,8 @@
 - Every database has a name: the key in `lancedb.databases`, or the path's stem
   for `--db PATH`, `db_path=` and the default database, which is the entry
   `haiku.rag` under `storage.data_dir` and selectable by that name.
-  `SearchResult.source`, `Document.source` and `Citation.source` always carry it.
+  `SearchResult.source`, `Document.source` and `Citation.source` carry it on
+  every value a database produces.
 - `db_path=` beside a configured `lancedb.databases` raises
   `AmbiguousDatabaseError` (`HaikuRAG`, `create_capability`, `create_mcp_server`,
   `Sandbox`). `haiku-rag --db PATH` and `haiku-ingester --db PATH` open that path

haiku_rag_slim/haiku/rag/cli.py

@@ -102,7 +102,10 @@ def resolve_scope(
             "pass --db or --db-name, not both: they name the same thing"
         )
     if db is not None:
+        try:
             return DatabaseScope.at(db)
+        except ValueError as error:
+            raise typer.BadParameter(str(error), param_hint="--db") from error
     scope = DatabaseScope.resolve(get_config(), database_name=_db_name)
     if scope.covers_multiple and not covers_set:
         raise AmbiguousDatabaseError(

haiku_rag_slim/haiku/rag/config/models.py

@@ -120,10 +120,15 @@ class LanceDBConfig(ConfigModel):
     @classmethod
     def _uri_names_its_replacement(cls, data: Any) -> Any:
         if isinstance(data, dict) and "uri" in data:
+            if str(data["uri"]).strip():
                 raise ValueError(
                     "lancedb.uri was removed; write lancedb.databases: {NAME: "
                     f"{data['uri']!r}}} instead"
                 )
+            raise ValueError(
+                "lancedb.uri was removed; remove the empty key. With no "
+                "lancedb.databases the database is haiku.rag under storage.data_dir"
+            )
         return data
 
     @model_validator(mode="after")

haiku_rag_slim/haiku/rag/ingester/cli.py

@@ -224,7 +224,12 @@ def _scope_for(db: Path | None) -> "DatabaseScope | None":
     is configured. None leaves placement to the configuration."""
     from haiku.rag.client.scope import DatabaseScope
 
-    return DatabaseScope.at(db) if db is not None else None
+    if db is None:
+        return None
+    try:
+        return DatabaseScope.at(db)
+    except ValueError as error:
+        raise typer.BadParameter(str(error), param_hint="--db") from error
 
 
 @_cli.command("serve")

tests/ingester/test_cli.py

@@ -547,6 +547,16 @@ class TestPlacingTheIngesterDatabase:
             tmp_path / "local.lancedb"
         )
 
+    def test_a_path_without_a_stem_is_a_usage_error(self):
+        from pathlib import Path
+
+        import typer
+
+        from haiku.rag.ingester.cli import _scope_for
+
+        with pytest.raises(typer.BadParameter, match="no name"):
+            _scope_for(Path("/"))
+
     def test_a_python_caller_cannot_pass_a_path(self):
         from haiku.rag.ingester.app import IngesterApp
 

tests/test_cli.py

@@ -169,6 +169,16 @@ class TestOneDatabaseCommands:
         assert scope.names == ("other",)
         assert not scope.covers_multiple
 
+    def test_a_path_without_a_stem_is_a_usage_error(self, monkeypatch):
+        """A path that names no database is the operator's mistake, reported as
+        one."""
+        import typer
+
+        self._install(monkeypatch)
+
+        with pytest.raises(typer.BadParameter, match="no name"):
+            resolve_scope(Path("/"))
+
     def test_no_configured_databases_is_allowed(self, monkeypatch, tmp_path):
         import haiku.rag.config as config_module
 

tests/test_config.py

@@ -812,7 +812,19 @@ def test_lancedb_uri_is_refused_with_the_replacement_named():
 
     message = str(raised.value)
     assert "lancedb.uri" in message
-    assert "lancedb.databases" in message
+    assert "lancedb.databases: {NAME: 's3://bucket/notes.lancedb'}" in message
 
     with pytest.raises(ValidationError, match="lancedb.databases"):
         LanceDBConfig.model_validate({"uri": "/data/notes.lancedb"})
+
+
+def test_an_empty_lancedb_uri_is_refused_with_removal_as_the_remedy():
+    """Generated configs carried `uri: ""` for the local default. The remedy is
+    to delete the key, never a mapping with an empty location."""
+    with pytest.raises(ValidationError) as raised:
+        AppConfig.model_validate({"lancedb": {"uri": ""}})
+
+    message = str(raised.value)
+    assert "lancedb.uri" in message
+    assert "remove" in message
+    assert "{NAME" not in message