feat(python): expose OAuth connection config (#3586)

Expose the merged Rust OAuth header provider through the Python async
connection path.

Includes:
- Python OAuthConfig and OAuthFlowType public config objects
- PyO3 conversion into the Rust OAuthConfig
- connect_async(oauth_config=...) plumbing
- repr redaction coverage for client_secret

Local validation: cargo fmt --all; ruff format/check on touched Python
files.

python/python/lancedb/__init__.py

@@ -89,6 +89,8 @@ def connect(
         If presented, connect to LanceDB cloud.
         Otherwise, connect to a database on file system or cloud storage.
         Can be set via environment variable `LANCEDB_API_KEY`.
+        OAuth configuration is currently supported only by ``connect_async``;
+        synchronous LanceDB Cloud connections require an API key.
     region: str, default "us-east-1"
         The region to use for LanceDB Cloud.
     host_override: str, optional
@@ -340,6 +342,7 @@ async def connect_async(
     session: Optional[Session] = None,
     manifest_enabled: bool = False,
     namespace_client_properties: Optional[Dict[str, str]] = None,
+    oauth_config=None,
 ) -> AsyncConnection:
     """Connect to a LanceDB database.
 
@@ -389,6 +392,10 @@ async def connect_async(
     namespace_client_properties : dict, optional
         Additional directory namespace client properties to use with
         ``manifest_enabled=True``.
+    oauth_config : OAuthConfig, optional
+        OAuth configuration for LanceDB Cloud/Enterprise. This is supported by
+        ``connect_async`` only; synchronous ``connect`` uses API key
+        authentication for ``db://`` URIs.
 
     Examples
     --------
@@ -435,6 +442,7 @@ async def connect_async(
             session,
             manifest_enabled,
             namespace_client_properties,
+            oauth_config,
         )
     )
 

python/python/lancedb/_lancedb.pyi

@@ -280,6 +280,7 @@ async def connect(
     session: Optional[Session],
     manifest_enabled: bool = False,
     namespace_client_properties: Optional[Dict[str, str]] = None,
+    oauth_config: Optional[Any] = None,
 ) -> Connection: ...
 
 class RecordBatchStream:

python/python/lancedb/remote/__init__.py

@@ -9,6 +9,7 @@ from typing import List, Optional
 from lancedb import __version__
 
 from .header import HeaderProvider
+from .oauth import OAuthConfig, OAuthFlowType
 
 __all__ = [
     "TimeoutConfig",
@@ -16,6 +17,8 @@ __all__ = [
     "TlsConfig",
     "ClientConfig",
     "HeaderProvider",
+    "OAuthConfig",
+    "OAuthFlowType",
 ]
 
 

python/python/lancedb/remote/oauth.py

@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright The LanceDB Authors
+
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import List, Optional
+
+
+class OAuthFlowType(str, Enum):
+    """OAuth authentication flow types."""
+
+    CLIENT_CREDENTIALS = "client_credentials"
+    """Client Credentials grant (service-to-service / M2M)."""
+
+    AZURE_MANAGED_IDENTITY = "azure_managed_identity"
+    """Azure Managed Identity via IMDS."""
+
+
+@dataclass
+class OAuthConfig:
+    """OAuth configuration for LanceDB authentication.
+
+    All token acquisition and refresh is handled in the Rust layer.
+    This config is passed through to Rust via PyO3.
+
+    Parameters
+    ----------
+    issuer_url : str
+        OIDC issuer URL or OAuth authority URL.
+        For Azure: ``https://login.microsoftonline.com/{tenant_id}/v2.0``
+    client_id : str
+        Application / Client ID.
+    scopes : List[str]
+        OAuth scopes to request.
+        For Azure managed identity, exactly one scope or resource is required.
+        For example: ``["api://{app_id}/.default"]``
+    flow : OAuthFlowType
+        Authentication flow to use. Default: CLIENT_CREDENTIALS.
+    client_secret : Optional[str]
+        Client secret (required for CLIENT_CREDENTIALS).
+    managed_identity_client_id : Optional[str]
+        Client ID for user-assigned managed identity (AZURE_MANAGED_IDENTITY).
+    refresh_buffer_secs : Optional[int]
+        Seconds before expiry to trigger proactive refresh (default: 300).
+        Keep this well below the token TTL; if it is greater than or equal to
+        the TTL, each request refreshes the token.
+
+    Examples
+    --------
+    Client Credentials (service-to-service):
+
+    >>> config = OAuthConfig(
+    ...     issuer_url="https://login.microsoftonline.com/{tenant}/v2.0",
+    ...     client_id="app-id",
+    ...     client_secret="secret",
+    ...     scopes=["api://lancedb-api/.default"],
+    ... )
+
+    Azure Managed Identity:
+
+    >>> config = OAuthConfig(
+    ...     issuer_url="https://login.microsoftonline.com/{tenant}/v2.0",
+    ...     client_id="app-id",
+    ...     scopes=["api://lancedb-api/.default"],
+    ...     flow=OAuthFlowType.AZURE_MANAGED_IDENTITY,
+    ... )
+    """
+
+    issuer_url: str
+    client_id: str
+    scopes: List[str]
+    flow: OAuthFlowType = OAuthFlowType.CLIENT_CREDENTIALS
+    client_secret: Optional[str] = field(default=None, repr=False)
+    managed_identity_client_id: Optional[str] = None
+    refresh_buffer_secs: Optional[int] = None