[BREAKING] Python: clean up kwargs across agents, chat clients, tools, and sessions (#4581)

* Python: clean up kwargs across agents, chat clients, tools, and sessions (#3642)

Audit and refactor public **kwargs usage across core agents, chat clients,
tools, sessions, and provider packages per the migration strategy codified
in CODING_STANDARD.md.

Key changes:
- Add explicit runtime buckets: function_invocation_kwargs and client_kwargs
  on RawAgent.run() and chat client get_response() layers.
- Refactor FunctionTool to prefer explicit ctx: FunctionInvocationContext
  injection; legacy **kwargs tools still work via _forward_runtime_kwargs.
- Refactor Agent.as_tool() to use direct JSON schema, always-streaming
  wrapper, approval_mode parameter, and UserInputRequiredException
  propagation (integrates PR #4568 behavior).
- Remove implicit session bleeding into FunctionInvocationContext; tools
  that need a session must receive it via function_invocation_kwargs.
- Lower chat-client layers after FunctionInvocationLayer accept only
  compatibility **kwargs (client_kwargs flattened, function_invocation_kwargs
  ignored).
- Add layered docstring composition from Raw... implementations via
  _docstrings.py helper.
- Clean up provider constructors to use explicit additional_properties.
- Deprecation warnings on legacy direct kwargs paths.
- Update samples, tests, and typing across all 23 packages.

Resolves #3642

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* clarified docstring

* feedback fixes

* Add unit tests for _docstrings.py build/apply helpers

Tests cover: no docstring source, no extra kwargs, appending to existing
Keyword Args section, inserting after Args, inserting in plain docstrings,
multiline descriptions, ordering, and apply_layered_docstring.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add test for propagate_session TypeError on non-AgentSession values

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add tests for multi-content and empty UserInputRequiredException propagation

Cover the branching logic in _try_execute_function_calls for:
- Multiple user_input_request items in a single exception (extra_user_input_contents path)
- Empty contents list (fallback function_result path)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add tests for DurableAIAgent.get_session forwarding service_session_id

Verifies get_session correctly forwards service_session_id and session_id
to the executor's get_new_session, replacing the removed kwargs test.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Simplify ag-ui test stub to read session from client_kwargs only

Remove dual-mode detection (client_kwargs vs raw kwargs fallback) from
the test mock. Session is now read exclusively from client_kwargs,
matching the settled public calling convention.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* updated create and get sessions in durable

* fixed docstrings

* fix test

* updated session handling

* updated from main

* updated tests

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/anthropic/agent_framework_anthropic/_chat_client.py

@@ -228,11 +228,11 @@ class AnthropicClient(
         model_id: str | None = None,
         anthropic_client: AsyncAnthropic | None = None,
         additional_beta_flags: list[str] | None = None,
+        additional_properties: dict[str, Any] | None = None,
         middleware: Sequence[ChatAndFunctionMiddlewareTypes] | None = None,
         function_invocation_configuration: FunctionInvocationConfiguration | None = None,
         env_file_path: str | None = None,
         env_file_encoding: str | None = None,
-        **kwargs: Any,
     ) -> None:
         """Initialize an Anthropic Agent client.
 
@@ -244,11 +244,11 @@ class AnthropicClient(
                 For instance if you need to set a different base_url for testing or private deployments.
             additional_beta_flags: Additional beta flags to enable on the client.
                 Default flags are: "mcp-client-2025-04-04", "code-execution-2025-08-25".
+            additional_properties: Additional properties stored on the client instance.
             middleware: Optional middleware to apply to the client.
             function_invocation_configuration: Optional function invocation configuration override.
             env_file_path: Path to environment file for loading settings.
             env_file_encoding: Encoding of the environment file.
-            kwargs: Additional keyword arguments passed to the parent class.
 
         Examples:
             .. code-block:: python
@@ -319,9 +319,9 @@ class AnthropicClient(
 
         # Initialize parent
         super().__init__(
+            additional_properties=additional_properties,
             middleware=middleware,
             function_invocation_configuration=function_invocation_configuration,
-            **kwargs,
         )
 
         # Initialize instance variables