From 3f59a25369fd0da7b968ebf14250e198e9b51e8d Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 00:34:18 +0000
Subject: [PATCH 1/6] chore(bigframes): Add support for bigframes-only project
 id env var

---
 packages/bigframes/bigframes/_config/env.py   | 47 +++++++++++++++++++
 packages/bigframes/bigframes/pandas/io/api.py |  6 ++-
 .../bigframes/bigframes/session/__init__.py   |  5 +-
 .../bigframes/bigframes/session/clients.py    | 18 +------
 4 files changed, 56 insertions(+), 20 deletions(-)
 create mode 100644 packages/bigframes/bigframes/_config/env.py

diff --git a/packages/bigframes/bigframes/_config/env.py b/packages/bigframes/bigframes/_config/env.py
new file mode 100644
index 000000000000..5600f03c0dce
--- /dev/null
+++ b/packages/bigframes/bigframes/_config/env.py
@@ -0,0 +1,47 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+
+from google.auth import default as auth_default
+
+from bigframes._config import options
+
+_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
+_GOOGLE_CLOUD_PROJECT = "GOOGLE_CLOUD_PROJECT"
+
+
+def get_default_project_id() -> str:
+    # Prefer the project in this order:
+    # 1. Project explicitly specified by the user
+    # 2. Project set in the environment
+    # 3. Project associated with the default credentials
+    maybe_from_env = (
+        config.options.bigquery.project
+        or os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT)
+        or os.getenv(_GOOGLE_CLOUD_PROJECT)
+    )
+    if maybe_from_env:
+        return maybe_from_env
+
+    import bigframes._config.auth as auth
+    _, creds_project = auth.get_default_credentials_with_project()
+
+    if not creds_project:
+        raise ValueError(
+            "Project must be set to initialize BigQuery client. "
+            "Try setting `bigframes.options.bigquery.project` first."
+        )
+
+    return creds_project
\ No newline at end of file
diff --git a/packages/bigframes/bigframes/pandas/io/api.py b/packages/bigframes/bigframes/pandas/io/api.py
index b7ed1a65d922..31771fa54214 100644
--- a/packages/bigframes/bigframes/pandas/io/api.py
+++ b/packages/bigframes/bigframes/pandas/io/api.py
@@ -655,9 +655,11 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
     # Address circular imports in doctest due to bigframes/session/__init__.py
     # containing a lot of logic and samples.
     from bigframes.session import clients
+    import bigframes._config.env as env
 
+    project_id = env.get_default_project_id()
     clients_provider = clients.ClientsProvider(
-        project=config.options.bigquery.project,
+        project=project_id,
         location=config.options.bigquery.location,
         use_regional_endpoints=config.options.bigquery.use_regional_endpoints,
         credentials=config.options.bigquery.credentials,
@@ -666,7 +668,7 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
         client_endpoints_override=config.options.bigquery.client_endpoints_override,
         requests_transport_adapters=config.options.bigquery.requests_transport_adapters,
     )
-    return clients_provider.bqclient, clients_provider._project
+    return clients_provider.bqclient, project
 
 
 def _dry_run(query, bqclient) -> bigquery.QueryJob:
diff --git a/packages/bigframes/bigframes/session/__init__.py b/packages/bigframes/bigframes/session/__init__.py
index afca1ed0554f..91bb50650d82 100644
--- a/packages/bigframes/bigframes/session/__init__.py
+++ b/packages/bigframes/bigframes/session/__init__.py
@@ -61,6 +61,7 @@
 )
 
 import bigframes._config
+import bigframes._config.env
 import bigframes._config.bigquery_options as bigquery_options
 import bigframes.clients
 import bigframes.constants
@@ -217,8 +218,10 @@ def __init__(
         if clients_provider:
             self._clients_provider = clients_provider
         else:
+            # will throw if cannot be determined
+            project = bigframes._config.env.get_default_project_id()
             self._clients_provider = clients.ClientsProvider(
-                project=context.project,
+                project=project,
                 location=self._location,
                 use_regional_endpoints=context.use_regional_endpoints,
                 credentials=context.credentials,
diff --git a/packages/bigframes/bigframes/session/clients.py b/packages/bigframes/bigframes/session/clients.py
index 2a5c9d649918..f4e47a5b524a 100644
--- a/packages/bigframes/bigframes/session/clients.py
+++ b/packages/bigframes/bigframes/session/clients.py
@@ -38,7 +38,6 @@
 
 from . import environment
 
-_ENV_DEFAULT_PROJECT = "GOOGLE_CLOUD_PROJECT"
 _APPLICATION_NAME = f"bigframes/{bigframes.version.__version__} ibis/9.2.0"
 
 
@@ -74,7 +73,7 @@ class ClientsProvider:
 
     def __init__(
         self,
-        project: Optional[str] = None,
+        project: str,
         location: Optional[str] = None,
         use_regional_endpoints: Optional[bool] = None,
         credentials: Optional[google.auth.credentials.Credentials] = None,
@@ -90,21 +89,6 @@ def __init__(
         if credentials is None:
             credentials, credentials_project = _get_default_credentials_with_project()
 
-        # Prefer the project in this order:
-        # 1. Project explicitly specified by the user
-        # 2. Project set in the environment
-        # 3. Project associated with the default credentials
-        project = (
-            project
-            or os.getenv(_ENV_DEFAULT_PROJECT)
-            or typing.cast(Optional[str], credentials_project)
-        )
-
-        if not project:
-            raise ValueError(
-                "Project must be set to initialize BigQuery client. "
-                "Try setting `bigframes.options.bigquery.project` first."
-            )
 
         self._application_name = (
             f"{_get_application_names()} {application_name}"

From 6fedddfc03e8693083d430fbea4d5d92ed6e2ffa Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 17:27:25 +0000
Subject: [PATCH 2/6] fixes

---
 packages/bigframes/bigframes/_config/env.py            | 7 +++----
 packages/bigframes/bigframes/pandas/io/api.py          | 2 +-
 packages/bigframes/bigframes/session/clients.py        | 1 -
 packages/bigframes/tests/system/large/test_location.py | 6 ++++--
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/packages/bigframes/bigframes/_config/env.py b/packages/bigframes/bigframes/_config/env.py
index 5600f03c0dce..ab3e1f02d14a 100644
--- a/packages/bigframes/bigframes/_config/env.py
+++ b/packages/bigframes/bigframes/_config/env.py
@@ -14,8 +14,6 @@
 
 import os
 
-from google.auth import default as auth_default
-
 from bigframes._config import options
 
 _BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
@@ -28,7 +26,7 @@ def get_default_project_id() -> str:
     # 2. Project set in the environment
     # 3. Project associated with the default credentials
     maybe_from_env = (
-        config.options.bigquery.project
+        options.bigquery.project
         or os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT)
         or os.getenv(_GOOGLE_CLOUD_PROJECT)
     )
@@ -36,6 +34,7 @@ def get_default_project_id() -> str:
         return maybe_from_env
 
     import bigframes._config.auth as auth
+
     _, creds_project = auth.get_default_credentials_with_project()
 
     if not creds_project:
@@ -44,4 +43,4 @@ def get_default_project_id() -> str:
             "Try setting `bigframes.options.bigquery.project` first."
         )
 
-    return creds_project
\ No newline at end of file
+    return creds_project
diff --git a/packages/bigframes/bigframes/pandas/io/api.py b/packages/bigframes/bigframes/pandas/io/api.py
index 31771fa54214..03c896434d7b 100644
--- a/packages/bigframes/bigframes/pandas/io/api.py
+++ b/packages/bigframes/bigframes/pandas/io/api.py
@@ -668,7 +668,7 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
         client_endpoints_override=config.options.bigquery.client_endpoints_override,
         requests_transport_adapters=config.options.bigquery.requests_transport_adapters,
     )
-    return clients_provider.bqclient, project
+    return clients_provider.bqclient, project_id
 
 
 def _dry_run(query, bqclient) -> bigquery.QueryJob:
diff --git a/packages/bigframes/bigframes/session/clients.py b/packages/bigframes/bigframes/session/clients.py
index f4e47a5b524a..f53ecaf3d701 100644
--- a/packages/bigframes/bigframes/session/clients.py
+++ b/packages/bigframes/bigframes/session/clients.py
@@ -89,7 +89,6 @@ def __init__(
         if credentials is None:
             credentials, credentials_project = _get_default_credentials_with_project()
 
-
         self._application_name = (
             f"{_get_application_names()} {application_name}"
             if application_name
diff --git a/packages/bigframes/tests/system/large/test_location.py b/packages/bigframes/tests/system/large/test_location.py
index 3ebe2bb040e4..083a13ae2d0c 100644
--- a/packages/bigframes/tests/system/large/test_location.py
+++ b/packages/bigframes/tests/system/large/test_location.py
@@ -177,7 +177,7 @@ def test_bq_rep_endpoints(bigquery_location):
 
 def test_clients_provider_no_location():
     with pytest.raises(ValueError, match="Must set location to use regional endpoints"):
-        bigframes.session.clients.ClientsProvider(use_regional_endpoints=True)
+        bigframes.session.clients.ClientsProvider(project="", use_regional_endpoints=True)
 
 
 @pytest.mark.parametrize(
@@ -191,7 +191,9 @@ def test_clients_provider_use_regional_endpoints_non_rep_locations(bigquery_loca
         match=f"not .*available in the location {bigquery_location}",
     ):
         bigframes.session.clients.ClientsProvider(
-            location=bigquery_location, use_regional_endpoints=True
+            project="",
+            location=bigquery_location, 
+            use_regional_endpoints=True
         )
 
 

From 788ad31fe7ff367dd37d6a68992824f4f1e5e6eb Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 20:31:00 +0000
Subject: [PATCH 3/6] fixes

---
 packages/bigframes/bigframes/_config/env.py   | 39 +++++++++++--------
 packages/bigframes/bigframes/pandas/io/api.py |  7 ++--
 .../bigframes/bigframes/session/__init__.py   |  7 ++--
 .../bigframes/bigframes/session/clients.py    | 11 +-----
 .../tests/system/large/test_location.py       |  6 ++-
 5 files changed, 36 insertions(+), 34 deletions(-)

diff --git a/packages/bigframes/bigframes/_config/env.py b/packages/bigframes/bigframes/_config/env.py
index ab3e1f02d14a..0c67fac31b6d 100644
--- a/packages/bigframes/bigframes/_config/env.py
+++ b/packages/bigframes/bigframes/_config/env.py
@@ -14,33 +14,38 @@
 
 import os
 
+from typing import Optional
 from bigframes._config import options
+import bigframes._config.bigquery_options as bigquery_options
 
 _BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
 _GOOGLE_CLOUD_PROJECT = "GOOGLE_CLOUD_PROJECT"
 
 
-def get_default_project_id() -> str:
-    # Prefer the project in this order:
-    # 1. Project explicitly specified by the user
-    # 2. Project set in the environment
-    # 3. Project associated with the default credentials
-    maybe_from_env = (
-        options.bigquery.project
-        or os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT)
-        or os.getenv(_GOOGLE_CLOUD_PROJECT)
-    )
-    if maybe_from_env:
-        return maybe_from_env
-
-    import bigframes._config.auth as auth
+def resolve_credentials_and_project(options: bigquery_options.BigQueryOptions) -> tuple[google.auth.credentials.Credentials, str]:
+    if project is None:
+        project = bigframes._config.env.get_default_project_id(context)
 
-    _, creds_project = auth.get_default_credentials_with_project()
+    if credentials is None:
+        credentials, cred_project = bigframes._config.auth.get_default_credentials_with_project()
+        if project is None:
+            project = cred_project
 
-    if not creds_project:
+    if project is None:
         raise ValueError(
             "Project must be set to initialize BigQuery client. "
             "Try setting `bigframes.options.bigquery.project` first."
         )
+    return credentials, project
 
-    return creds_project
+
+def get_default_project_id() -> Optional[str]:
+    # Prefer the project in this order:
+    # 1. Project explicitly specified by the user
+    # 2. Project set in the environment
+    # 3. Project associated with the default credentials
+    return (
+        bigframes._config.options.project
+        or os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT)
+        or os.getenv(_GOOGLE_CLOUD_PROJECT)
+    )
\ No newline at end of file
diff --git a/packages/bigframes/bigframes/pandas/io/api.py b/packages/bigframes/bigframes/pandas/io/api.py
index 03c896434d7b..3b10ed699f2d 100644
--- a/packages/bigframes/bigframes/pandas/io/api.py
+++ b/packages/bigframes/bigframes/pandas/io/api.py
@@ -657,12 +657,13 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
     from bigframes.session import clients
     import bigframes._config.env as env
 
-    project_id = env.get_default_project_id()
+    credentials, project = bigframes._config.env.resolve_credentials_and_project(config.options.bigquery)
+
     clients_provider = clients.ClientsProvider(
-        project=project_id,
+        project=project,
         location=config.options.bigquery.location,
         use_regional_endpoints=config.options.bigquery.use_regional_endpoints,
-        credentials=config.options.bigquery.credentials,
+        credentials=credentials,
         application_name=config.options.bigquery.application_name,
         bq_kms_key_name=config.options.bigquery.kms_key_name,
         client_endpoints_override=config.options.bigquery.client_endpoints_override,
diff --git a/packages/bigframes/bigframes/session/__init__.py b/packages/bigframes/bigframes/session/__init__.py
index 91bb50650d82..856e04530461 100644
--- a/packages/bigframes/bigframes/session/__init__.py
+++ b/packages/bigframes/bigframes/session/__init__.py
@@ -61,6 +61,7 @@
 )
 
 import bigframes._config
+import bigframes._config.auth
 import bigframes._config.env
 import bigframes._config.bigquery_options as bigquery_options
 import bigframes.clients
@@ -218,13 +219,13 @@ def __init__(
         if clients_provider:
             self._clients_provider = clients_provider
         else:
-            # will throw if cannot be determined
-            project = bigframes._config.env.get_default_project_id()
+            credentials, project = bigframes._config.env.resolve_credentials_and_project(context)
+
             self._clients_provider = clients.ClientsProvider(
                 project=project,
+                credentials=credentials,
                 location=self._location,
                 use_regional_endpoints=context.use_regional_endpoints,
-                credentials=context.credentials,
                 application_name=context.application_name,
                 bq_kms_key_name=self._bq_kms_key_name,
                 client_endpoints_override=context.client_endpoints_override,
diff --git a/packages/bigframes/bigframes/session/clients.py b/packages/bigframes/bigframes/session/clients.py
index f53ecaf3d701..f3046c7cbe0f 100644
--- a/packages/bigframes/bigframes/session/clients.py
+++ b/packages/bigframes/bigframes/session/clients.py
@@ -32,7 +32,6 @@
 import google.cloud.storage  # type: ignore
 import requests
 
-import bigframes._config.auth
 import bigframes.constants
 import bigframes.version
 
@@ -49,10 +48,6 @@
 _BIGQUERYSTORAGE_REGIONAL_ENDPOINT = "bigquerystorage.{location}.rep.googleapis.com"
 
 
-def _get_default_credentials_with_project():
-    return bigframes._config.auth.get_default_credentials_with_project()
-
-
 def _get_application_names():
     apps = [_APPLICATION_NAME]
 
@@ -74,9 +69,9 @@ class ClientsProvider:
     def __init__(
         self,
         project: str,
+        credentials: google.auth.credentials.Credentials,
         location: Optional[str] = None,
         use_regional_endpoints: Optional[bool] = None,
-        credentials: Optional[google.auth.credentials.Credentials] = None,
         application_name: Optional[str] = None,
         bq_kms_key_name: Optional[str] = None,
         client_endpoints_override: dict = {},
@@ -85,10 +80,6 @@ def __init__(
             Tuple[str, requests.adapters.BaseAdapter]
         ] = (),
     ):
-        credentials_project = None
-        if credentials is None:
-            credentials, credentials_project = _get_default_credentials_with_project()
-
         self._application_name = (
             f"{_get_application_names()} {application_name}"
             if application_name
diff --git a/packages/bigframes/tests/system/large/test_location.py b/packages/bigframes/tests/system/large/test_location.py
index 083a13ae2d0c..fe48ee36396c 100644
--- a/packages/bigframes/tests/system/large/test_location.py
+++ b/packages/bigframes/tests/system/large/test_location.py
@@ -176,8 +176,10 @@ def test_bq_rep_endpoints(bigquery_location):
 
 
 def test_clients_provider_no_location():
+    credentials = mock.create_autospec(google.auth.credentials.Credentials)
+
     with pytest.raises(ValueError, match="Must set location to use regional endpoints"):
-        bigframes.session.clients.ClientsProvider(project="", use_regional_endpoints=True)
+        bigframes.session.clients.ClientsProvider(project="", credentials=credentials, use_regional_endpoints=True)
 
 
 @pytest.mark.parametrize(
@@ -186,12 +188,14 @@ def test_clients_provider_no_location():
     sorted(bigframes.constants.REP_NOT_ENABLED_BIGQUERY_LOCATIONS),
 )
 def test_clients_provider_use_regional_endpoints_non_rep_locations(bigquery_location):
+    credentials = mock.create_autospec(google.auth.credentials.Credentials)
     with pytest.raises(
         ValueError,
         match=f"not .*available in the location {bigquery_location}",
     ):
         bigframes.session.clients.ClientsProvider(
             project="",
+            credentials=credentials,
             location=bigquery_location, 
             use_regional_endpoints=True
         )

From 1bf9d4a590d1780e8cb8ec2b37faa83d66665dc1 Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 20:39:28 +0000
Subject: [PATCH 4/6] fixes

---
 packages/bigframes/bigframes/_config/auth.py  | 45 +++++++++++++++-
 packages/bigframes/bigframes/_config/env.py   | 51 -------------------
 packages/bigframes/bigframes/pandas/io/api.py |  6 +--
 .../bigframes/bigframes/session/__init__.py   |  3 +-
 4 files changed, 48 insertions(+), 57 deletions(-)
 delete mode 100644 packages/bigframes/bigframes/_config/env.py

diff --git a/packages/bigframes/bigframes/_config/auth.py b/packages/bigframes/bigframes/_config/auth.py
index 1574fc488355..92b66bc2f393 100644
--- a/packages/bigframes/bigframes/_config/auth.py
+++ b/packages/bigframes/bigframes/_config/auth.py
@@ -14,6 +14,7 @@
 
 from __future__ import annotations
 
+import os
 import threading
 from typing import Optional
 
@@ -21,6 +22,11 @@
 import google.auth.transport.requests
 import pydata_google_auth
 
+from typing import Optional
+from bigframes._config import options
+import bigframes._config.bigquery_options as bigquery_options
+import google.auth.credentials
+
 _SCOPES = ["https://www.googleapis.com/auth/cloud-platform"]
 
 # Put the lock here rather than in BigQueryOptions so that BigQueryOptions
@@ -30,7 +36,44 @@
 _cached_project_default: Optional[str] = None
 
 
-def get_default_credentials_with_project() -> tuple[
+_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
+_GOOGLE_CLOUD_PROJECT = "GOOGLE_CLOUD_PROJECT"
+
+
+def resolve_credentials_and_project(
+    options: bigquery_options.BigQueryOptions,
+) -> tuple[google.auth.credentials.Credentials, str]:
+    project = options.project
+    credentials = options.credentials
+    if project is None:
+        project = _get_env_project_id()
+
+    if credentials is None:
+        credentials, cred_project = _get_default_credentials_with_project()
+        # This might conflict with explicit project, which will be ignored, credentials project
+        # only used if nothing else specified
+        if project is None:
+            project = cred_project
+
+    if project is None:
+        raise ValueError(
+            "Project must be set to initialize BigQuery client. "
+            "Try setting `bigframes.options.bigquery.project` first."
+        )
+    return credentials, project
+
+
+def _get_env_project_id() -> Optional[str]:
+    # Prefer the project in this order:
+    # 1. Project explicitly specified by the user
+    # 2. Project set in the environment
+    # 3. Project associated with the default credentials
+    return os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT) or os.getenv(
+        _GOOGLE_CLOUD_PROJECT
+    )
+
+
+def _get_default_credentials_with_project() -> tuple[
     google.auth.credentials.Credentials, Optional[str]
 ]:
     global _AUTH_LOCK, _cached_credentials, _cached_project_default
diff --git a/packages/bigframes/bigframes/_config/env.py b/packages/bigframes/bigframes/_config/env.py
deleted file mode 100644
index 0c67fac31b6d..000000000000
--- a/packages/bigframes/bigframes/_config/env.py
+++ /dev/null
@@ -1,51 +0,0 @@
-# Copyright 2024 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-import os
-
-from typing import Optional
-from bigframes._config import options
-import bigframes._config.bigquery_options as bigquery_options
-
-_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
-_GOOGLE_CLOUD_PROJECT = "GOOGLE_CLOUD_PROJECT"
-
-
-def resolve_credentials_and_project(options: bigquery_options.BigQueryOptions) -> tuple[google.auth.credentials.Credentials, str]:
-    if project is None:
-        project = bigframes._config.env.get_default_project_id(context)
-
-    if credentials is None:
-        credentials, cred_project = bigframes._config.auth.get_default_credentials_with_project()
-        if project is None:
-            project = cred_project
-
-    if project is None:
-        raise ValueError(
-            "Project must be set to initialize BigQuery client. "
-            "Try setting `bigframes.options.bigquery.project` first."
-        )
-    return credentials, project
-
-
-def get_default_project_id() -> Optional[str]:
-    # Prefer the project in this order:
-    # 1. Project explicitly specified by the user
-    # 2. Project set in the environment
-    # 3. Project associated with the default credentials
-    return (
-        bigframes._config.options.project
-        or os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT)
-        or os.getenv(_GOOGLE_CLOUD_PROJECT)
-    )
\ No newline at end of file
diff --git a/packages/bigframes/bigframes/pandas/io/api.py b/packages/bigframes/bigframes/pandas/io/api.py
index 3b10ed699f2d..fd3f42d599bb 100644
--- a/packages/bigframes/bigframes/pandas/io/api.py
+++ b/packages/bigframes/bigframes/pandas/io/api.py
@@ -655,9 +655,9 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
     # Address circular imports in doctest due to bigframes/session/__init__.py
     # containing a lot of logic and samples.
     from bigframes.session import clients
-    import bigframes._config.env as env
+    import bigframes._config.auth
 
-    credentials, project = bigframes._config.env.resolve_credentials_and_project(config.options.bigquery)
+    credentials, project = bigframes._config.auth.resolve_credentials_and_project(config.options.bigquery)
 
     clients_provider = clients.ClientsProvider(
         project=project,
@@ -669,7 +669,7 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
         client_endpoints_override=config.options.bigquery.client_endpoints_override,
         requests_transport_adapters=config.options.bigquery.requests_transport_adapters,
     )
-    return clients_provider.bqclient, project_id
+    return clients_provider.bqclient, project
 
 
 def _dry_run(query, bqclient) -> bigquery.QueryJob:
diff --git a/packages/bigframes/bigframes/session/__init__.py b/packages/bigframes/bigframes/session/__init__.py
index 856e04530461..6a65c92d2bfa 100644
--- a/packages/bigframes/bigframes/session/__init__.py
+++ b/packages/bigframes/bigframes/session/__init__.py
@@ -62,7 +62,6 @@
 
 import bigframes._config
 import bigframes._config.auth
-import bigframes._config.env
 import bigframes._config.bigquery_options as bigquery_options
 import bigframes.clients
 import bigframes.constants
@@ -219,7 +218,7 @@ def __init__(
         if clients_provider:
             self._clients_provider = clients_provider
         else:
-            credentials, project = bigframes._config.env.resolve_credentials_and_project(context)
+            credentials, project = bigframes._config.auth.resolve_credentials_and_project(context)
 
             self._clients_provider = clients.ClientsProvider(
                 project=project,

From b628e51f5a3485919feff00f32ef035eb67cfe43 Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 20:41:35 +0000
Subject: [PATCH 5/6] lint

---
 packages/bigframes/bigframes/pandas/io/api.py          | 4 +++-
 packages/bigframes/bigframes/session/__init__.py       | 4 +++-
 packages/bigframes/tests/system/large/test_location.py | 8 +++++---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/bigframes/bigframes/pandas/io/api.py b/packages/bigframes/bigframes/pandas/io/api.py
index fd3f42d599bb..e412f5f2798a 100644
--- a/packages/bigframes/bigframes/pandas/io/api.py
+++ b/packages/bigframes/bigframes/pandas/io/api.py
@@ -657,7 +657,9 @@ def _get_bqclient_and_project() -> Tuple[bigquery.Client, str]:
     from bigframes.session import clients
     import bigframes._config.auth
 
-    credentials, project = bigframes._config.auth.resolve_credentials_and_project(config.options.bigquery)
+    credentials, project = bigframes._config.auth.resolve_credentials_and_project(
+        config.options.bigquery
+    )
 
     clients_provider = clients.ClientsProvider(
         project=project,
diff --git a/packages/bigframes/bigframes/session/__init__.py b/packages/bigframes/bigframes/session/__init__.py
index 6a65c92d2bfa..05d979b4eb9c 100644
--- a/packages/bigframes/bigframes/session/__init__.py
+++ b/packages/bigframes/bigframes/session/__init__.py
@@ -218,7 +218,9 @@ def __init__(
         if clients_provider:
             self._clients_provider = clients_provider
         else:
-            credentials, project = bigframes._config.auth.resolve_credentials_and_project(context)
+            credentials, project = (
+                bigframes._config.auth.resolve_credentials_and_project(context)
+            )
 
             self._clients_provider = clients.ClientsProvider(
                 project=project,
diff --git a/packages/bigframes/tests/system/large/test_location.py b/packages/bigframes/tests/system/large/test_location.py
index fe48ee36396c..54af1d4ca9b6 100644
--- a/packages/bigframes/tests/system/large/test_location.py
+++ b/packages/bigframes/tests/system/large/test_location.py
@@ -179,7 +179,9 @@ def test_clients_provider_no_location():
     credentials = mock.create_autospec(google.auth.credentials.Credentials)
 
     with pytest.raises(ValueError, match="Must set location to use regional endpoints"):
-        bigframes.session.clients.ClientsProvider(project="", credentials=credentials, use_regional_endpoints=True)
+        bigframes.session.clients.ClientsProvider(
+            project="", credentials=credentials, use_regional_endpoints=True
+        )
 
 
 @pytest.mark.parametrize(
@@ -196,8 +198,8 @@ def test_clients_provider_use_regional_endpoints_non_rep_locations(bigquery_loca
         bigframes.session.clients.ClientsProvider(
             project="",
             credentials=credentials,
-            location=bigquery_location, 
-            use_regional_endpoints=True
+            location=bigquery_location,
+            use_regional_endpoints=True,
         )
 
 

From b9a969cdde9da3e788fb189209e7954a4533d269 Mon Sep 17 00:00:00 2001
From: Trevor Bergeron <tbergeron@google.com>
Date: Wed, 29 Apr 2026 21:55:42 +0000
Subject: [PATCH 6/6] remove var, refactor only

---
 packages/bigframes/bigframes/_config/auth.py    | 17 ++---------------
 .../tests/system/large/test_location.py         |  2 ++
 2 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/packages/bigframes/bigframes/_config/auth.py b/packages/bigframes/bigframes/_config/auth.py
index 92b66bc2f393..3b05c878db95 100644
--- a/packages/bigframes/bigframes/_config/auth.py
+++ b/packages/bigframes/bigframes/_config/auth.py
@@ -22,10 +22,8 @@
 import google.auth.transport.requests
 import pydata_google_auth
 
-from typing import Optional
-from bigframes._config import options
 import bigframes._config.bigquery_options as bigquery_options
-import google.auth.credentials
+from bigframes._config import options
 
 _SCOPES = ["https://www.googleapis.com/auth/cloud-platform"]
 
@@ -36,7 +34,6 @@
 _cached_project_default: Optional[str] = None
 
 
-_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT = "BIGFRAMES_DEFAULT_PROJECT"
 _GOOGLE_CLOUD_PROJECT = "GOOGLE_CLOUD_PROJECT"
 
 
@@ -46,7 +43,7 @@ def resolve_credentials_and_project(
     project = options.project
     credentials = options.credentials
     if project is None:
-        project = _get_env_project_id()
+        project = os.getenv(_GOOGLE_CLOUD_PROJECT)
 
     if credentials is None:
         credentials, cred_project = _get_default_credentials_with_project()
@@ -63,16 +60,6 @@ def resolve_credentials_and_project(
     return credentials, project
 
 
-def _get_env_project_id() -> Optional[str]:
-    # Prefer the project in this order:
-    # 1. Project explicitly specified by the user
-    # 2. Project set in the environment
-    # 3. Project associated with the default credentials
-    return os.getenv(_BIGFRAMES_SPECIFIC_ENV_DEFAULT_PROJECT) or os.getenv(
-        _GOOGLE_CLOUD_PROJECT
-    )
-
-
 def _get_default_credentials_with_project() -> tuple[
     google.auth.credentials.Credentials, Optional[str]
 ]:
diff --git a/packages/bigframes/tests/system/large/test_location.py b/packages/bigframes/tests/system/large/test_location.py
index 54af1d4ca9b6..3127d5865a95 100644
--- a/packages/bigframes/tests/system/large/test_location.py
+++ b/packages/bigframes/tests/system/large/test_location.py
@@ -13,7 +13,9 @@
 # limitations under the License.
 
 import typing
+import unittest.mock as mock
 
+import google.auth.credentials
 import pandas
 import pandas.testing
 import pytest