[BUG] Tokens in A2A response should be represented as Artifact Update events, not Status Updates

[brycewcole]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

1.20

Python Version

3.12

Operating System

macOS 26.2

Installation Method

other

Steps to Reproduce

1. Follow official A2A tutorial at https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/runtime-a2a.html
2. Use A2A Inspector or similar product to send message.
3. Observe tokens streamed

Expected Behavior

Result messages should be streamed as artifact-update events with append set to true. Please see discussion on A2A's repo here.

Actual Behavior

Tokens were streamed as status-update events.

Additional Context

Possible Solution

Stream as artifact-update with append set to true

Related Issues

No response

[brycewcole]

I made a PR for this as it's causing unexpected behaviour when interacting with other a2a agents.
#1401