Python: [Samples][Python] a2a/ sample missing requirements.txt — beginners cannot install dependencies

[leestott]

Description

The python/samples/04-hosting/a2a/ sample has no requirements.txt file. Unlike every other sample in 04-hosting/, a beginner who creates a .venv and tries pip install has no dependency file to reference.

The README recommends uv run python a2a_server.py, which only works when executed from the repo root with the uv workspace properly configured — a setup most beginners won't have.

Steps to Reproduce

cd python/samples/04-hosting/a2a
python -m venv .venv
.venv\Scripts\Activate.ps1
pip install -r requirements.txt   # ❌ File not found

Verified Missing Dependencies

Confirmed via import tests in a clean .venv:

Package	Import That Fails
agent-framework-a2a	from agent_framework.a2a import A2AAgent → ModuleNotFoundError: The 'agent-framework-a2a' package is not installed
uvicorn	import uvicorn → ModuleNotFoundError: No module named 'uvicorn'
agent-framework-foundry	Needed for FoundryChatClient in a2a_server.py
httpx	Used in agent_with_a2a.py
python-dotenv	Used across all scripts

Also Missing

• No .env.example or .env.template file. Users must read source code to discover FOUNDRY_PROJECT_ENDPOINT, FOUNDRY_MODEL, and A2A_AGENT_HOST.

Suggested Fix

1. Add a requirements.txt with local editable paths (matching the pattern used in durabletask/ and azure_functions/ samples).
2. Add a .env.example with the required environment variables.

Environment

• Python 3.13.13, Windows 11, uv 0.9.27