Python: Fix StandardMagenticManager to propagate session to manager agent

[moonbox3]

Motivation and Context

StandardMagenticManager did not create or pass an AgentSession when calling its internal agent's run() method. This caused context providers (e.g. RedisHistoryProvider) configured on the manager agent to silently fail, since they rely on a session to scope and retrieve conversation history.

Fixes #4371

Description

The root cause was that StandardMagenticManager._complete() called self._agent.run(messages) without a session argument, so context providers never received the session they need to function. The fix creates a persistent AgentSession during manager initialization and passes it on every run() call. Additionally, the session is included in checkpoint save/restore so it survives orchestration snapshots.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

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Note: PR autogenerated by moonbox3's agent

[moonbox3]

Automated Code Review

Reviewers: 3 | Confidence: 77%

✓ Correctness

The diff correctly adds AgentSession propagation to StandardMagenticManager—creating a session in init, passing it through to agent.run(), and handling checkpoint save/restore. The implementation is consistent with existing patterns (e.g., task_ledger checkpoint handling). The two new async test functions are missing @pytest.mark.asyncio decorators, which will cause them to be silently skipped (or collected as warnings) unless the project has asyncio_mode='auto' configured globally. Additionally, test_standard_manager_checkpoint_preserves_session is declared async but never awaits anything.

✓ Security Reliability

The diff adds AgentSession lifecycle management to StandardMagenticManager, including checkpoint serialization/deserialization. The implementation follows existing patterns in the codebase. No critical security vulnerabilities were found. The deserialization path uses from_dict (not pickle), which is safe. The broad exception catch on restore is consistent with the adjacent task_ledger handling. One minor reliability concern: the truthiness check on the restored payload could silently skip restoration for edge-case falsy values.

✗ Test Coverage

Two new async tests cover session propagation and checkpoint round-tripping, with strong identity/value assertions. However, both async tests lack @pytest.mark.asyncio (a problem if the project does not use asyncio_mode='auto'), backward-compatible checkpoint restore (state without 'agent_session') is untested, and the AgentSession import may be missing from the test module.

Blocking Issues

• Both new async test functions lack the @pytest.mark.asyncio decorator. If the project's pytest config does not set asyncio_mode = 'auto', these tests will silently pass without executing any assertions, giving false confidence. Verify the pytest configuration, and if auto mode is not enabled, add the decorator.

Suggestions

• The two new test functions are async def but lack @pytest.mark.asyncio decorators. If the project does not use asyncio_mode = "auto", these tests will be silently skipped. Verify the pytest-asyncio configuration or add the decorators explicitly.
• test_standard_manager_checkpoint_preserves_session does not await anything—it could be a plain synchronous test function, which would make it run regardless of asyncio configuration.
• Consider using if session_payload is not None: instead of if session_payload: to guard against edge cases where AgentSession.to_dict() might return a valid but falsy value (e.g., an empty dict). The current truthiness check would silently skip restoration in that scenario, leaving the manager with a fresh session and no warning logged.
• Add a test that restores a checkpoint saved without 'agent_session' (backward compatibility). The production code already handles this via state.get(), but there is no test proving the old checkpoint format still works.
• Confirm that AgentSession is already imported in test_magentic.py; the diff does not show it being added to the test file's imports, yet the type annotation list[AgentSession | None] on line 1084 depends on it.
• Consider a test that calls _complete (or plan) after on_checkpoint_restore to verify the restored session is actually propagated to subsequent agent.run() calls, not just that the session_id matches.

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Automated review by moonbox3's agents

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/orchestrations/agent_framework_orchestrations
_magentic.py	591	91	84%	64–73, 78, 82–93, 258, 269, 273, 293, 354, 363, 365, 407, 424, 433–434, 436–438, 440, 451, 594, 596, 636, 684, 720–722, 724, 734, 742–743, 810–813, 904, 910, 916, 958, 996, 1028, 1045, 1056, 1111–1112, 1116–1118, 1142, 1166–1167, 1180, 1196, 1218, 1266–1267, 1305–1306, 1469, 1472, 1481, 1484, 1489, 1540–1541, 1582–1583, 1631, 1661, 1719, 1733, 1744
TOTAL	22259	2752	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
4728	247 💤	0 ❌	0 🔥	1m 18s ⏱️

[Copilot]

Pull request overview

This PR fixes a bug in the Python Magentic orchestration where StandardMagenticManager invoked its underlying manager agent without an AgentSession, preventing session-scoped context providers (e.g., history providers) from working correctly.

Changes:

• Create a persistent AgentSession in StandardMagenticManager and pass it to every internal agent.run(...) call.
• Persist/restore the manager’s session via checkpoint save/restore.
• Add regression tests validating session propagation and checkpoint preservation.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
python/packages/orchestrations/agent_framework_orchestrations/_magentic.py	Create/reuse an AgentSession for manager-agent runs and include it in checkpoint state.
python/packages/orchestrations/tests/test_magentic.py	Add tests ensuring session is propagated consistently and survives checkpoint restore.