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A2A inbound message conversion ignores Message.role, always maps to "model" #5186
Description
Bug Description
convert_a2a_message_to_event() in to_adk_event.py hard-codes role="model" for all resulting ADK events, regardless of the original A2A Message.role. User messages (Role.user) are incorrectly restored as model events.
The task history fallback (a2a_task.history[-1]) also does not check Message.role, so a trailing user message can be treated as agent output.
Steps to Reproduce
from a2a.types import Message, Part, TextPart, Role
user_msg = Message(
role=Role.user,
parts=[Part(root=TextPart(text="Hello"))],
metadata={}
)
event = convert_a2a_message_to_event(user_msg, author="user")
# event author is always "model" — should reflect "user"Expected Behavior
- A2A
Role.usershould map to an ADK event withrole="user" - History fallback should only use agent-role messages to avoid misattribution
Affected Files
src/google/adk/a2a/converters/to_adk_event.py
Activity
enjoykumawat commentedon Apr 7, 2026
I'd like to work on this. The fix should map
Message.roleto the correct ADK event author/role instead of hard-coding"model"inconvert_a2a_message_to_event(). Will submit a PR shortly.fix: map A2A Message.role to correct GenAI content role
anowardear062-svg commentedon Apr 7, 2026
Thanks
fix: respect A2A Message.role in inbound event conversion (google#5186)
fix: respect A2A Message.role in inbound event conversion (google#5186)
fix: respect A2A Message.role in inbound event conversion (google#5186)
fix: map A2A Message.role to correct GenAI content role
surajksharma07 commentedon Apr 9, 2026
@YizukiAme _create_event() in to_adk_event.py hardcodes role="model" and never reads a2a_message.role, which is what's causing the misattribution.
As a quick workaround, try wrapping convert_a2a_message_to_event() and fixing the role post-call via event.model_copy(update={"content": event.content.model_copy(update={"role": "user" if msg.role == Role.user else "model"})}).
It's also worth filtering history[-1] to agent-role only to avoid the second misattribution while you're in there.
Could you give that a try and let us know if it clears both issues on your end?
PR #5224 is already heading in this direction, so your confirmation there before it moves forward would be really helpful!
YizukiAme commentedon Apr 9, 2026
Thanks @surajksharma07! I reviewed the diff in PR #5224 and the fix looks correct for both issues:
(I originally found this via code audit rather than a live A2A setup, so my verification is code-level. But the root cause was a hardcoded string, and the fix + regression tests clearly address it.)
LGTM from the reporter side~ 👍
surajksharma07 commentedon Apr 10, 2026
Thanks for the thorough review @YizukiAme — a code-level LGTM is completely valid here given the root cause was a straightforward hardcode with no ambiguity.
We currently have two PRs open targeting the same fix (#5198 by @enjoykumawat and #5224 by @giulio-leone), so the team will review both and consolidate before merging.
We'll get this closed out once one lands — really appreciate you circling back so quickly!
surajksharma07 commentedon Apr 10, 2026
@Jacksunwei Please have a look into it once.
fix: respect A2A Message.role in inbound event conversion (google#5186)
fix: map A2A Message.role to correct GenAI content role
fix: respect A2A Message.role in inbound event conversion
fix: map A2A Message.role to correct GenAI content role
fix: respect A2A Message.role in inbound event conversion