Internal logging utility: _DeferredString

[rodrigobr-msft]

This pull request introduces a new utility for deferred string evaluation and refactors logging in the MSAL authentication code to improve performance and maintainability. The main changes are the addition of the _DeferredString class and its use for deferred logging, replacing a custom implementation.

Deferred string evaluation utility:

• Added _DeferredString class in microsoft_agents/activity/_utils/_deferred_string.py to allow deferred evaluation of expensive string operations, improving logging efficiency.
• Exposed _DeferredString through the package’s __init__.py for easier import.

Refactoring logging in MSAL authentication:

• Removed the custom _DeferredLogOfBlueprintId class from msal_auth.py and replaced its usage with the new _DeferredString utility for deferred logging of decoded JWT blueprint IDs.
• Updated the debug log statement in get_agentic_instance_token to use _DeferredString, ensuring JWT decoding only occurs if the log level is set to DEBUG.
• Imported the new utility in msal_auth.py for use in logging.

[Copilot]

Pull Request Overview

This PR introduces a reusable _DeferredString utility class to optimize logging performance by deferring expensive string operations until they're actually needed. The implementation replaces a custom deferred logging class in the MSAL authentication code with this new generalized utility.

Key Changes:

• Added a new _DeferredString utility class that defers function execution until string conversion
• Refactored MSAL authentication logging to use the new utility instead of a custom implementation
• Improved code maintainability by centralizing deferred string evaluation logic

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
_deferred_string.py	Introduces the _DeferredString class for deferred function evaluation
_utils/__init__.py	Exports the _DeferredString class from the utils module
msal_auth.py	Replaces custom _DeferredLogOfBlueprintId class with _DeferredString utility

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[cleemullins]

This is nice.

Are there other places we're doing logging that this should be used?

I image there are a number of "Activity Log" type calls, which need to be replaced. I think Claude 4.5 or Copilot should be able to find them all for you quick quickly.

[rodrigobr-msft]

This is nice.

Are there other places we're doing logging that this should be used?

I image there are a number of "Activity Log" type calls, which need to be replaced. I think Claude 4.5 or Copilot should be able to find them all for you quick quickly.

Fortunately, those are already handled by replacing format strings substitution with "%s" for lazy evaluation. We don't often go out of our way to perform lazy computation in this codebase. I asked Copilot, and all I found were uses of format strings. There's a lot of those, and I already started the conversion in the UserTokenClient and ConnectorClient classes in a separate PR. Thus, I will proceed and merge this.