Prototype: A2A support through a protocols abstraction

[ryanycoleman]

Description

This PR is intended as a WIP prototype to demonstrate possibilities and facilitate discussion about #24.

Introduces a protocol abstraction layer inspired by the model provider abstraction layer, enabling agents to be exposed as network services. Uses A2A support to exercise the abstraction layer, providing a one-line way to serve an endpoint, generate agent cards dynamically from the tools registry, and invoke remote agents like local tools.
See examples/iss_agent.py & examples/iss_client.py to try it out.

Type of Change

• New feature

Testing

To try this prototype:

• create a folder and new python environment (e.g. uv venv & source .venv/bin/activate)
• Install packages in this specific order to avoid conflicts with the git checkout
• uv pip install strands-agents-tools a2a-sdk fastapi
• uv pip install git+https://github.com/ryanycoleman/strands-sdk.git@prototype/a2a "strands-agents-tools==0.1.4" --no-deps
• create and run iss_agent.py in the background (e.g. uv run iss_agent.py &)
• create and run iss_client.py (e.g. uv run iss_client.py)
• have a peek at the auto-generated agent card (e.g. curl localhost:8000/.well-known/agent.json | jq)

[How have you tested the change?] Just the new feature in isolation.

• hatch fmt --linter
• hatch fmt --formatter
• hatch test --all
• Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

Checklist

• I have read the CONTRIBUTING document
• I have added tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature
• My changes generate no new warnings
• Any dependent changes have been merged and published

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[ryanycoleman]

Excited to close this PR in favor of #218