Python: [BREAKING] Renamed next middleware parameter to call_next

[dmytrostruk]

Motivation and Context

Resolves: #3583

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.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework
_middleware.py	329	16	95%	80, 83, 88, 797, 799, 801, 922, 949, 951, 976, 1057, 1061, 1185, 1189, 1250, 1324
packages/orchestrations/agent_framework_orchestrations
_handoff.py	380	61	83%	104–105, 107, 136–137, 159–169, 171, 173, 175, 180, 280, 334, 359, 387, 395–396, 410, 461–462, 494, 541–543, 737, 744, 749, 836, 839, 848–851, 861, 866, 873, 879–882, 917, 922, 1003–1004, 1036–1037, 1117, 1120, 1128, 1146, 1153, 1228
packages/purview/agent_framework_purview
_middleware.py	95	0	100%
TOTAL	16592	2059	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3920	225 💤	0 ❌	0 🔥	1m 7s ⏱️

[Copilot]

Pull request overview

This PR standardizes the Python middleware “next step” parameter name from next to call_next across the Agent Framework Python codebase, samples, and documentation to avoid shadowing Python’s built-in next().

Changes:

• Renamed middleware callback parameter next → call_next throughout Python samples and docs.
• Updated core middleware abstractions/docs and dependent package middleware implementations to use call_next.
• Updated unit tests to reflect the new middleware parameter name.

Reviewed changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
python/samples/getting_started/middleware/thread_behavior_middleware.py	Renames middleware parameter and doc text to call_next.
python/samples/getting_started/middleware/shared_state_middleware.py	Renames function middleware parameter to call_next.
python/samples/getting_started/middleware/runtime_context_delegation.py	Renames function middleware parameter to call_next across examples.
python/samples/getting_started/middleware/override_result_with_middleware.py	Renames chat/agent middleware parameter to call_next.
python/samples/getting_started/middleware/middleware_termination.py	Renames agent middleware parameter to call_next and updates explanatory text.
python/samples/getting_started/middleware/function_based_middleware.py	Renames agent/function middleware parameter to call_next and updates comments.
python/samples/getting_started/middleware/exception_handling_with_middleware.py	Renames function middleware parameter to call_next.
python/samples/getting_started/middleware/decorator_middleware.py	Renames decorator-based middleware parameter to call_next.
python/samples/getting_started/middleware/class_based_middleware.py	Renames class-based middleware parameter to call_next and updates comments.
python/samples/getting_started/middleware/chat_middleware.py	Renames chat middleware parameter to call_next.
python/samples/getting_started/middleware/agent_and_run_level_middleware.py	Renames agent/run/function middleware parameters to call_next and updates comments.
python/samples/getting_started/devui/weather_agent_azure/agent.py	Renames chat/function middleware parameters to call_next.
python/samples/getting_started/agents/openai/openai_responses_client_with_agent_as_tool.py	Renames function middleware parameter to call_next.
python/samples/getting_started/agents/openai/openai_responses_client_basic.py	Renames chat middleware parameter to call_next.
python/samples/getting_started/agents/azure_ai/azure_ai_with_agent_as_tool.py	Renames function middleware parameter to call_next.
python/samples/concepts/tools/README.md	Updates diagrams and narrative from next to call_next.
python/packages/purview/agent_framework_purview/_middleware.py	Renames overridden middleware method parameter to call_next.
python/packages/orchestrations/agent_framework_orchestrations/_handoff.py	Renames function middleware parameter to call_next.
python/packages/ollama/tests/test_ollama_chat_client.py	Updates test middleware function parameter to call_next.
python/packages/core/tests/core/test_middleware_with_chat.py	Updates chat middleware tests to use call_next.
python/packages/core/tests/core/test_middleware_with_agent.py	Updates agent/function/chat middleware tests to use call_next.
python/packages/core/tests/core/test_middleware_context_result.py	Updates context.result-related middleware tests to use call_next.
python/packages/core/tests/core/test_middleware.py	Updates pipeline tests to use call_next.
python/packages/core/tests/core/test_as_tool_kwargs_propagation.py	Updates agent middleware in kwargs propagation tests to use call_next.
python/packages/core/agent_framework/_middleware.py	Updates middleware docs/examples and core signatures to call_next; updates related error text.
python/packages/core/AGENTS.md	Updates middleware example parameter name to call_next (but example semantics need correction).

Comments suppressed due to low confidence (1)

python/packages/core/tests/core/test_middleware_with_agent.py:1758

• This statement is unreachable.

                await call_next(context)

[moonbox3]

LGTM. Small nit: can we adjust the PR description to show some motivation and context as to why we're renaming (we understand internally, but external readers may not).

[moonbox3]

LGTM. Small nit: can we adjust the PR description to show some motivation and context as to why we're renaming (we understand internally, but external readers may not).

Sorry, I overlooked that you linked to some context. Disregard if you want...