Python: Fix AG-UI reasoning role and multimodal media parsing to follow specification

[moonbox3]

Motivation and Context

The AG-UI adapter emitted role="assistant" on ReasoningMessageStartEvent instead of the spec-required role="reasoning", causing reasoning messages to render incorrectly in AG-UI clients. Additionally, _parse_multimodal_media_part read the deprecated "data" field instead of the current spec's "value" field, silently dropping all user-submitted multimodal media.

Fixes #5340

Description

Changed ReasoningMessageStartEvent role from "assistant" to "reasoning" in both the flow and non-flow code paths of _emit_text_reasoning in _run_common.py. Updated _parse_multimodal_media_part in _message_adapters.py to read source_dict.get("value") first (with fallback to "data" for backward compatibility) for base64/data source types and the unknown-type fallback branch. Bumped the ag-ui-protocol dependency from pined 0.1.13 to >=0.1.16,<0.2 to pick up the upstream SDK fix for the reasoning role type. Added targeted regression tests for both the reasoning role and multimodal value-field parsing.

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.

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Note: PR autogenerated by moonbox3's agent

[moonbox3]

Automated Code Review

Reviewers: 4 | Confidence: 96% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

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Automated review by moonbox3's agents

[moonbox3]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/ag-ui/agent_framework_ag_ui
_message_adapters.py	597	55	90%	102–103, 112–115, 118–122, 124–129, 132, 141–147, 187, 318, 408–411, 413–415, 462–464, 518, 521, 523, 526, 529, 545, 562, 584, 684, 700–701, 772, 794, 864, 899–900, 968, 1011
_run_common.py	307	10	96%	381–382, 388–393, 701–702
TOTAL	28982	3476	88%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
5760	30 💤	0 ❌	0 🔥	1m 31s ⏱️

[Copilot]

Pull request overview

Fixes the Python AG-UI adapter to align with the AG-UI specification for reasoning event roles and multimodal media payload parsing, and updates the AG-UI protocol dependency/tests accordingly.

Changes:

• Emit ReasoningMessageStartEvent(role="reasoning") (instead of "assistant") in both streaming and non-streaming reasoning paths.
• Parse multimodal media payloads from source.value first (with fallback to deprecated source.data) for base64/data/unknown source types.
• Update ag-ui-protocol dependency (and lockfile) and add regression tests for both fixes.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
python/packages/ag-ui/agent_framework_ag_ui/_run_common.py	Sets reasoning message start role to "reasoning" in both flow and non-flow paths.
python/packages/ag-ui/agent_framework_ag_ui/_message_adapters.py	Prefers source.value over source.data when parsing multimodal media payloads.
python/packages/ag-ui/pyproject.toml	Relaxes ag-ui-protocol pin to >=0.1.16,<0.2 to pick up upstream fix.
python/uv.lock	Locks ag-ui-protocol to 0.1.17 and updates metadata specifier accordingly.
python/packages/ag-ui/tests/ag_ui/test_run.py	Updates existing reasoning role assertion and adds targeted flow/non-flow role regression tests.
python/packages/ag-ui/tests/ag_ui/test_message_adapters.py	Adds regression tests ensuring value is used (and preferred) for multimodal media parsing.
python/samples/04-hosting/foundry-hosted-agents/responses/02_local_tools/main.py	Import ordering adjustment (moves Annotated import into the stdlib section).
python/samples/02-agents/conversations/file_history_provider.py	Adds inline Pyright ignore for optional orjson import.
python/samples/02-agents/conversations/file_history_provider_conversation_persistence.py	Adds inline Pyright ignore for optional orjson import.
.maf-runtime-ready	Adds a new repo-root marker file.

[moonbox3]

Automated Code Review

Reviewers: 4 | Confidence: 94% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

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Automated review by moonbox3's agents

[Rickyneer]

To: @moonbox3
Thank you for the fast response to my issue.

I do want to note that this does not fix the issue completely and with this fix, another part of the bug has popped up.
The place in which you patched the multimodal media parsing code, is not the only code that needs to be modified. An identical snippet of code that does the exact same thing (I recall in a function that is called _legacy_binary_parsing or something similar, also in the same file), which I think was for creating snapshot events, also looks for the wrong field "data" which should be field "value". This results in ag-ui compatible clients to crash when trying to ingest the snapshot event.
Maybe it's better to put both of these same code snippets behind a single function so it'll be easier to update in the future?
I hope to hear your opinion on this.

Thank you in advance.