Python: Improve AzureAIAgent get thread msg handling.

[moonbox3]

Motivation and Context

Currently, when fetching thread messages for an AzureAIAgent, it assumes that the agent exists, so we can pull it down and get its id. This may not always be the case - an agent could have been deleted, but the thread still exists. We need to account for this.

When creating user messages that we add to the thread, there's no name or id parameter allowed. We can, however, add metadata to the message. Going forward we are adding the agent_id as metadata to the message, so upon retrieval later, we can attempt to get it and return the id with the user's message. This allows one to see which agent_id has responded to the user's message:

# Messages in the thread (asc order):

# AuthorRole.USER for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: Hello
# AuthorRole.ASSISTANT for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: Hello! How can I assist you with the menu today?
# AuthorRole.USER for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: What is the special soup?
# AuthorRole.ASSISTANT for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: The special soup today is Clam Chowder. Would you like to know more about it or anything else on the menu?
# AuthorRole.USER for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: How much does that cost?
# AuthorRole.ASSISTANT for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: The Clam Chowder costs $9.99. Would you like to order it or need information on other items?
# AuthorRole.USER for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: Thank you
# AuthorRole.ASSISTANT for name=asst_mXwZOwyJLxXGtaYKHizRH6Ip: You're welcome! If you have any more questions or need assistance with the menu, feel free to ask. Enjoy your meal!

Description

• Closes Python: Bug: AgentThreadActions get_messages #12435

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
agents
agent.py	338	49	85%	122, 129, 142–143, 146–148, 151–153, 204, 209, 214, 219, 224, 228, 232, 236, 277–279, 307–308, 310, 314, 434, 436, 501, 515, 578, 580, 605, 619, 632, 684, 691–692, 695–696, 715, 762, 819, 904–905, 907–908, 962, 1023, 1038
agents/azure_ai
agent_thread_actions.py	362	140	61%	154, 156, 193–196, 288, 292, 296, 299, 302–303, 307, 310, 313–314, 318, 321, 324–325, 329–330, 430, 432, 472–473, 495, 497–499, 501–503, 505–506, 508–513, 515–523, 527–528, 531–534, 538, 541–542, 545–546, 549, 552, 555–559, 561–562, 566–567, 574–575, 580, 584–585, 587–588, 595, 597, 601, 603–604, 608–617, 619–621, 624, 674, 677, 711–712, 719–723, 783, 788–793, 821–824, 828, 833–834, 838, 855–857, 861–862, 877–878, 916, 957–960, 962–963, 967, 971–972, 977
TOTAL	26417	4504	82%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3638	22 💤	0 ❌	0 🔥	1m 54s ⏱️