diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index 86e164a3..52e5b60d 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -36,6 +36,21 @@ Examples:
 - Follow PEP 8 conventions.
 - Use `autopep8` for Python formatting.
 
+## Copyright Headers
+
+Every new Python (`.py`) source file MUST begin with the following copyright
+header as the first two lines, followed by a blank line before any code,
+docstring, or imports:
+
+```python
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+```
+
+This applies to all hand-written Python files, including `__init__.py` files,
+tests, and examples. The only exceptions are auto-generated protobuf files
+(`*_pb2.py` and `*_pb2_grpc.py`), which carry their own generated header.
+
 ## Python Type Checking
 
 Before linting, check for and fix any Pylance errors in the files you
diff --git a/durabletask-azuremanaged/__init__.py b/durabletask-azuremanaged/__init__.py
index e69de29b..59e481eb 100644
--- a/durabletask-azuremanaged/__init__.py
+++ b/durabletask-azuremanaged/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/durabletask-azuremanaged/durabletask/azuremanaged/__init__.py b/durabletask-azuremanaged/durabletask/azuremanaged/__init__.py
index e69de29b..59e481eb 100644
--- a/durabletask-azuremanaged/durabletask/azuremanaged/__init__.py
+++ b/durabletask-azuremanaged/durabletask/azuremanaged/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/durabletask/entities/durable_entity.py b/durabletask/entities/durable_entity.py
index 2963a188..b93b21af 100644
--- a/durabletask/entities/durable_entity.py
+++ b/durabletask/entities/durable_entity.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from typing import Any, TypeVar, overload
 
 from durabletask.entities.entity_context import EntityContext
diff --git a/durabletask/entities/entity_context.py b/durabletask/entities/entity_context.py
index ba2e18e6..03ece715 100644
--- a/durabletask/entities/entity_context.py
+++ b/durabletask/entities/entity_context.py
@@ -1,3 +1,5 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
 
 from typing import Any, TypeVar, overload
 import uuid
diff --git a/durabletask/entities/entity_instance_id.py b/durabletask/entities/entity_instance_id.py
index dc2340d7..9c984877 100644
--- a/durabletask/entities/entity_instance_id.py
+++ b/durabletask/entities/entity_instance_id.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 class EntityInstanceId:
     def __init__(self, entity: str, key: str):
         EntityInstanceId.validate_entity_name(entity)
diff --git a/durabletask/entities/entity_lock.py b/durabletask/entities/entity_lock.py
index 0b237016..87598964 100644
--- a/durabletask/entities/entity_lock.py
+++ b/durabletask/entities/entity_lock.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
diff --git a/durabletask/entities/entity_metadata.py b/durabletask/entities/entity_metadata.py
index fbbea000..a2ed2191 100644
--- a/durabletask/entities/entity_metadata.py
+++ b/durabletask/entities/entity_metadata.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from datetime import datetime, timezone
 from typing import Any, TypeVar, overload
 from durabletask.entities.entity_instance_id import EntityInstanceId
diff --git a/durabletask/entities/entity_operation_failed_exception.py b/durabletask/entities/entity_operation_failed_exception.py
index a69094ee..e9ebb581 100644
--- a/durabletask/entities/entity_operation_failed_exception.py
+++ b/durabletask/entities/entity_operation_failed_exception.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from durabletask.internal.orchestrator_service_pb2 import TaskFailureDetails
 from durabletask.entities.entity_instance_id import EntityInstanceId
 
diff --git a/durabletask/internal/entity_state_shim.py b/durabletask/internal/entity_state_shim.py
index 130de029..6d6fd25b 100644
--- a/durabletask/internal/entity_state_shim.py
+++ b/durabletask/internal/entity_state_shim.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from typing import Any, TypeVar, overload
 
 import durabletask.internal.orchestrator_service_pb2 as pb
diff --git a/durabletask/internal/exceptions.py b/durabletask/internal/exceptions.py
index 30273a64..276cbe60 100644
--- a/durabletask/internal/exceptions.py
+++ b/durabletask/internal/exceptions.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import durabletask.internal.orchestrator_service_pb2 as pb
 
 
diff --git a/durabletask/internal/json_encode_output_exception.py b/durabletask/internal/json_encode_output_exception.py
index c6c9cc4e..29192c15 100644
--- a/durabletask/internal/json_encode_output_exception.py
+++ b/durabletask/internal/json_encode_output_exception.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from typing import Any
 
 
diff --git a/durabletask/internal/orchestration_entity_context.py b/durabletask/internal/orchestration_entity_context.py
index f4d5d1d5..e47d2ab5 100644
--- a/durabletask/internal/orchestration_entity_context.py
+++ b/durabletask/internal/orchestration_entity_context.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from collections.abc import Generator
 from datetime import datetime
 from typing import Any
diff --git a/durabletask/internal/proto_task_hub_sidecar_service_stub.py b/durabletask/internal/proto_task_hub_sidecar_service_stub.py
index de5a4d5e..d907a4e7 100644
--- a/durabletask/internal/proto_task_hub_sidecar_service_stub.py
+++ b/durabletask/internal/proto_task_hub_sidecar_service_stub.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from collections.abc import Callable
 from typing import Any, Protocol
 
diff --git a/examples/activity_sequence.py b/examples/activity_sequence.py
index b4b92ea7..d031c5c5 100644
--- a/examples/activity_sequence.py
+++ b/examples/activity_sequence.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import logging
diff --git a/examples/entities/class_based_entity.py b/examples/entities/class_based_entity.py
index e1b581d5..82749b1b 100644
--- a/examples/entities/class_based_entity.py
+++ b/examples/entities/class_based_entity.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/examples/entities/class_based_entity_actions.py b/examples/entities/class_based_entity_actions.py
index 5240bb75..8c397673 100644
--- a/examples/entities/class_based_entity_actions.py
+++ b/examples/entities/class_based_entity_actions.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/examples/entities/entity_locking.py b/examples/entities/entity_locking.py
index c6c1bda9..11d52f8f 100644
--- a/examples/entities/entity_locking.py
+++ b/examples/entities/entity_locking.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/examples/entities/function_based_entity.py b/examples/entities/function_based_entity.py
index b99c29b4..7e62e891 100644
--- a/examples/entities/function_based_entity.py
+++ b/examples/entities/function_based_entity.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/examples/entities/function_based_entity_actions.py b/examples/entities/function_based_entity_actions.py
index edcdbee2..42834b6c 100644
--- a/examples/entities/function_based_entity_actions.py
+++ b/examples/entities/function_based_entity_actions.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/examples/fanout_fanin.py b/examples/fanout_fanin.py
index 0975d924..3c635d10 100644
--- a/examples/fanout_fanin.py
+++ b/examples/fanout_fanin.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that a dynamic number activity functions in parallel, waits for them all
 to complete, and prints an aggregate summary of the outputs."""
diff --git a/examples/human_interaction.py b/examples/human_interaction.py
index 69131006..c0060b62 100644
--- a/examples/human_interaction.py
+++ b/examples/human_interaction.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that waits for an "approval" event before proceding to the next step. If
 the approval isn't received within a specified timeout, the order that is
diff --git a/examples/sandboxes/main_app.py b/examples/sandboxes/main_app.py
index 41f6f609..ff234e76 100644
--- a/examples/sandboxes/main_app.py
+++ b/examples/sandboxes/main_app.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """Declarer app for the Durable Task Scheduler sandbox activities sample."""
 
 import os
diff --git a/examples/sandboxes/remote_worker.py b/examples/sandboxes/remote_worker.py
index afd22b80..515e391c 100644
--- a/examples/sandboxes/remote_worker.py
+++ b/examples/sandboxes/remote_worker.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """Remote worker image entrypoint for the Durable Task Scheduler sandbox activities sample."""
 
 import os
diff --git a/examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py b/examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py
index eef2edc6..c8cfe648 100644
--- a/examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py
+++ b/examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import os
 from azure.identity import DefaultAzureCredential
 from durabletask import client
diff --git a/examples/sub-orchestrations-with-fan-out-fan-in/worker.py b/examples/sub-orchestrations-with-fan-out-fan-in/worker.py
index 45620cda..df2e61f2 100644
--- a/examples/sub-orchestrations-with-fan-out-fan-in/worker.py
+++ b/examples/sub-orchestrations-with-fan-out-fan-in/worker.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import os
 import random
 import time
diff --git a/examples/version_aware_orchestrator.py b/examples/version_aware_orchestrator.py
index b0af11a4..a8fc7ef6 100644
--- a/examples/version_aware_orchestrator.py
+++ b/examples/version_aware_orchestrator.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that a dynamic number activity functions in parallel, waits for them all
 to complete, and prints an aggregate summary of the outputs."""
diff --git a/examples/work_item_filtering.py b/examples/work_item_filtering.py
index 8bccb7f9..06933196 100644
--- a/examples/work_item_filtering.py
+++ b/examples/work_item_filtering.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to use work item filters
 to control which orchestrations and activities a worker processes."""
 import os
diff --git a/tests/__init__.py b/tests/__init__.py
index e69de29b..59e481eb 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/tests/durabletask-azuremanaged/__init__.py b/tests/durabletask-azuremanaged/__init__.py
index e69de29b..59e481eb 100644
--- a/tests/durabletask-azuremanaged/__init__.py
+++ b/tests/durabletask-azuremanaged/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/tests/durabletask-azuremanaged/entities/__init__.py b/tests/durabletask-azuremanaged/entities/__init__.py
index e69de29b..59e481eb 100644
--- a/tests/durabletask-azuremanaged/entities/__init__.py
+++ b/tests/durabletask-azuremanaged/entities/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/tests/durabletask-azuremanaged/entities/test_dts_class_based_entities_e2e.py b/tests/durabletask-azuremanaged/entities/test_dts_class_based_entities_e2e.py
index 0910f88e..ff6522f2 100644
--- a/tests/durabletask-azuremanaged/entities/test_dts_class_based_entities_e2e.py
+++ b/tests/durabletask-azuremanaged/entities/test_dts_class_based_entities_e2e.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from datetime import datetime, timezone
 import os
 import time
diff --git a/tests/durabletask-azuremanaged/entities/test_dts_entity_failure_handling.py b/tests/durabletask-azuremanaged/entities/test_dts_entity_failure_handling.py
index b12d158e..5cc1d444 100644
--- a/tests/durabletask-azuremanaged/entities/test_dts_entity_failure_handling.py
+++ b/tests/durabletask-azuremanaged/entities/test_dts_entity_failure_handling.py
@@ -1,3 +1,5 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
 
 import json
 import os
diff --git a/tests/durabletask-azuremanaged/entities/test_dts_function_based_entities_e2e.py b/tests/durabletask-azuremanaged/entities/test_dts_function_based_entities_e2e.py
index 2fbf2018..11d61a92 100644
--- a/tests/durabletask-azuremanaged/entities/test_dts_function_based_entities_e2e.py
+++ b/tests/durabletask-azuremanaged/entities/test_dts_function_based_entities_e2e.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 from datetime import datetime, timezone
 import os
 import time
diff --git a/tests/durabletask-azuremanaged/test_dts_activity_sequence.py b/tests/durabletask-azuremanaged/test_dts_activity_sequence.py
index 1a685d0d..3f9f5e64 100644
--- a/tests/durabletask-azuremanaged/test_dts_activity_sequence.py
+++ b/tests/durabletask-azuremanaged/test_dts_activity_sequence.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """End-to-end sample that demonstrates how to configure an orchestrator
 that calls an activity function in a sequence and prints the outputs."""
 import os
diff --git a/tests/durabletask-azuremanaged/test_dts_batch_actions.py b/tests/durabletask-azuremanaged/test_dts_batch_actions.py
index e709c412..97167b98 100644
--- a/tests/durabletask-azuremanaged/test_dts_batch_actions.py
+++ b/tests/durabletask-azuremanaged/test_dts_batch_actions.py
@@ -1,3 +1,5 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
 
 import asyncio
 import logging
diff --git a/tests/durabletask/entities/test_entity_id_parsing.py b/tests/durabletask/entities/test_entity_id_parsing.py
index c56a8787..77bb339e 100644
--- a/tests/durabletask/entities/test_entity_id_parsing.py
+++ b/tests/durabletask/entities/test_entity_id_parsing.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import pytest
 from durabletask.entities import EntityInstanceId
 
diff --git a/tests/durabletask/extensions/__init__.py b/tests/durabletask/extensions/__init__.py
index e69de29b..59e481eb 100644
--- a/tests/durabletask/extensions/__init__.py
+++ b/tests/durabletask/extensions/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/tests/durabletask/extensions/history_export/__init__.py b/tests/durabletask/extensions/history_export/__init__.py
index e69de29b..59e481eb 100644
--- a/tests/durabletask/extensions/history_export/__init__.py
+++ b/tests/durabletask/extensions/history_export/__init__.py
@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
diff --git a/tests/durabletask/test_client.py b/tests/durabletask/test_client.py
index 2fe48517..5ccd8958 100644
--- a/tests/durabletask/test_client.py
+++ b/tests/durabletask/test_client.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import asyncio
 import inspect
 import json
diff --git a/tests/durabletask/test_entity_executor.py b/tests/durabletask/test_entity_executor.py
index 851edd7d..c3f369df 100644
--- a/tests/durabletask/test_entity_executor.py
+++ b/tests/durabletask/test_entity_executor.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 """Unit tests for the _EntityExecutor class in durabletask.worker."""
 import logging
 
diff --git a/tests/durabletask/test_worker_concurrency_loop.py b/tests/durabletask/test_worker_concurrency_loop.py
index 199c2198..e7f802a6 100644
--- a/tests/durabletask/test_worker_concurrency_loop.py
+++ b/tests/durabletask/test_worker_concurrency_loop.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import asyncio
 import threading
 import time
diff --git a/tests/durabletask/test_worker_concurrency_loop_async.py b/tests/durabletask/test_worker_concurrency_loop_async.py
index 22ffe237..686e12b8 100644
--- a/tests/durabletask/test_worker_concurrency_loop_async.py
+++ b/tests/durabletask/test_worker_concurrency_loop_async.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import asyncio
 
 from durabletask.worker import ConcurrencyOptions, TaskHubGrpcWorker
diff --git a/tests/durabletask/test_worker_resiliency.py b/tests/durabletask/test_worker_resiliency.py
index a25529fe..1bc637dc 100644
--- a/tests/durabletask/test_worker_resiliency.py
+++ b/tests/durabletask/test_worker_resiliency.py
@@ -1,3 +1,6 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
 import asyncio
 import grpc
 from threading import Event, Timer