Python: Add load_dotenv() to samples for .env file support (#4043)

* Initial plan

* Add load_dotenv() to 303 Python samples for environment variable loading

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Update SAMPLE_GUIDELINES.md to document load_dotenv() requirement

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Update samples README.md to document .env file usage

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Run ruff format on all changed sample files

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Clarify load_dotenv() usage in README - local dev vs production

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove deprecated getting_started folder as requested

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Document env_file_path parameter for per-client configuration

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Merge main branch to resolve conflicts

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix run_evaluation.py file that was empty in merge commit

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove dotnet changes from merge - out of scope for this PR

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove package and test changes from merge - only sample changes needed

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove test_func_utils.py - only sample changes needed

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Revert sample files not in original changeset - keep only load_dotenv additions

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Move load_dotenv() outside snippet tag in 06_host_your_agent.py

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix comment placement - move load_dotenv before code comments

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix load_dotenv() placement across all samples - after docstring, before code comments

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Merge latest main branch with load_dotenv changes

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove non-sample changes from merge - keep only load_dotenv additions

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Revert non-load_dotenv sample changes from merge

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix run_evaluation.py - use main's improved version (file already had load_dotenv)

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Manual update

* Manual update 2

* Fix Role usage and load_dotenv placement per PR review feedback

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Fix Role usage - use string literals not enum attributes

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Fix SAMPLE_GUIDELINES.md example - load_dotenv before docstring per guidance

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Move load_dotenv() before docstrings in all samples per SAMPLE_GUIDELINES ordering

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Address PR review: rename files, fix placement, add session usage, remove note

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Update Redis README to reference renamed file redis_history_provider.py

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>
Co-authored-by: Tao Chen <taochen@microsoft.com>
Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>
Co-authored-by: Eduard van Valkenburg <eavanvalkenburg@users.noreply.github.com>

python/samples/03-workflows/checkpoint/checkpoint_with_human_in_the_loop.py

@@ -8,18 +8,6 @@ from datetime import datetime
 from pathlib import Path
 from typing import Any
 
-from azure.identity import AzureCliCredential
-
-if sys.version_info >= (3, 12):
-    from typing import override  # type: ignore # pragma: no cover
-else:
-    from typing_extensions import override  # type: ignore[import] # pragma: no cover
-
-
-# NOTE: the Azure client imports above are real dependencies. When running this
-# sample outside of Azure-enabled environments you may wish to swap in the
-# `agent_framework.builtin` chat client or mock the writer executor. We keep the
-# concrete import here so readers can see an end-to-end configuration.
 from agent_framework import (
     AgentExecutor,
     AgentExecutorRequest,
@@ -34,6 +22,16 @@ from agent_framework import (
     response_handler,
 )
 from agent_framework.azure import AzureOpenAIResponsesClient
+from azure.identity import AzureCliCredential
+from dotenv import load_dotenv
+
+if sys.version_info >= (3, 12):
+    from typing import override  # type: ignore # pragma: no cover
+else:
+    from typing_extensions import override  # type: ignore[import] # pragma: no cover
+
+# Load environment variables from .env file
+load_dotenv()
 
 """
 Sample: Checkpoint + human-in-the-loop quickstart.

python/samples/03-workflows/checkpoint/workflow_as_agent_checkpoint.py

@@ -34,10 +34,15 @@ from agent_framework import (
 from agent_framework.azure import AzureOpenAIResponsesClient
 from agent_framework.orchestrations import SequentialBuilder
 from azure.identity import AzureCliCredential
+from dotenv import load_dotenv
+
+# Load environment variables from .env file
+load_dotenv()
 
 
 async def basic_checkpointing() -> None:
     """Demonstrate basic checkpoint storage with workflow-as-agent."""
+
     print("=" * 60)
     print("Basic Checkpointing with Workflow as Agent")
     print("=" * 60)