Python: Added internal kwargs filtering for Anthropic client

[dmytrostruk]

Motivation and Context

Resolves: #3502

Added filtering of internal kwargs for Anthropic client to avoid passing them when making API calls.

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.

[Copilot]

Pull request overview

This PR adds internal kwargs filtering to Python chat clients to prevent framework-internal parameters from being passed to chat client implementations. This fixes issue #3502 where _function_middleware_pipeline and other internal kwargs were incorrectly being passed to the Anthropic client, causing errors.

Changes:

• Added _filter_internal_kwargs() utility function to filter out internal framework kwargs (underscore-prefixed, thread, middleware)
• Applied filtering in BaseChatClient.get_response() and get_streaming_response() before calling _inner_get_response() and _inner_get_streaming_response()
• Added comprehensive unit tests for the filtering function and integration tests verifying the filtering works in both response methods

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
python/packages/core/agent_framework/_clients.py	Added _filter_internal_kwargs() function and applied it in get_response() and get_streaming_response() methods to filter kwargs before passing to implementation methods
python/packages/core/tests/core/test_clients.py	Added comprehensive tests for _filter_internal_kwargs() function and integration tests verifying filtering in both get_response() and get_streaming_response() methods

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/anthropic/agent_framework_anthropic
_chat_client.py	363	150	58%	367, 390, 392, 407, 429–432, 441, 443, 480–484, 486, 488–489, 491, 496–497, 499, 532–533, 542, 544–545, 550, 567–568, 610, 625, 629–630, 646, 655, 657, 661–662, 705–707, 709, 722–723, 730–732, 736–738, 742–745, 756, 758, 780, 790, 812–818, 825–826, 834–835, 843–846, 853–854, 860–861, 867–868, 874, 882–884, 888, 895–896, 902–903, 909–910, 916, 924–927, 934–935, 954, 961–962, 981, 1003, 1005, 1014–1015, 1021, 1043–1044, 1050–1051, 1060–1070, 1077–1083, 1090–1096, 1103–1112, 1119–1122
TOTAL	16250	2024	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3721	221 💤	0 ❌	0 🔥	1m 6s ⏱️