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Giles Odigwe 5affc9c333 Python: Reorganize A2A samples and use package A2AExecutor (#6165)
* Reorganize A2A samples: client demos in 02-agents, use package A2AExecutor

- Move client samples (agent_with_a2a, a2a_agent_as_function_tools) to samples/02-agents/a2a/
- Add new concept samples: polling, stream reconnection, protocol selection
- Replace sample agent_executor.py with package-level A2AExecutor (stream=True)
- Update 04-hosting/a2a to focus on server-side, point to 02-agents for clients
- Add README.md for the new 02-agents/a2a/ sample collection

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix streaming artifact coalescing and address PR review feedback

A2AExecutor fix:
- Generate a stable artifact_id per stream in _run_stream so all streaming
  chunks share the same ID, enabling proper append=True coalescing per the
  A2A spec (TaskArtifactUpdateEvent with same artifactId).
- Previously, item.message_id was None for OpenAI/Foundry streaming updates,
  causing the SDK to generate a new random UUID per token (100+ separate
  artifacts instead of 1 appended artifact).

Sample improvements:
- Replace join workaround with response.text now that coalescing works
- Add background=True to stream reconnection resume call (required for
  continuation token emission on in-progress tasks)
- Fix type ignore specificity in polling sample

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-06-01 07:09:11 +00:00

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Markdown

# A2A Server Hosting Examples
This sample demonstrates how to **host** Agent Framework agents as A2A-compliant servers using the [A2A (Agent2Agent) protocol](https://a2a-protocol.org/latest/).
> **Looking for client samples?** See [`samples/02-agents/a2a/`](../../02-agents/a2a/) for consuming remote A2A agents.
## Server Samples
| Run this file | To... |
|---------------|-------|
| **[`a2a_server.py`](a2a_server.py)** | Host an Agent Framework agent as an A2A-compliant server (multi-agent). |
| **[`agent_framework_to_a2a.py`](agent_framework_to_a2a.py)** | Minimal example: expose a single agent as an A2A server. |
## Supporting Modules
| File | Description |
|------|-------------|
| [`agent_definitions.py`](agent_definitions.py) | Agent and AgentCard factory definitions for invoice, policy, and logistics agents. |
| [`invoice_data.py`](invoice_data.py) | Mock invoice data and tool functions for the invoice agent. |
| [`a2a_server.http`](a2a_server.http) | REST Client requests for testing the server directly from VS Code. |
## Environment Variables
### Required (Server)
- `FOUNDRY_PROJECT_ENDPOINT` — Your Azure AI Foundry project endpoint
- `FOUNDRY_MODEL` — Model deployment name (e.g. `gpt-4o`)
## Quick Start
All commands below should be run from this directory:
```powershell
cd python/samples/04-hosting/a2a
```
### 0. Install Dependencies
Copy `.env.example` to `.env` and fill in your values:
```powershell
copy .env.example .env
```
**Option A — pip (standard):**
```powershell
python -m venv .venv
.venv\Scripts\Activate.ps1 # Windows
# source .venv/bin/activate # macOS / Linux
pip install -r requirements.txt
```
**Option B — uv:**
```powershell
uv run python a2a_server.py --agent-type policy
```
### 1. Start the A2A Server
> **Note (Option A — pip users):** Replace `uv run python` with `python` in all `uv run` commands below. `uv` is not required once the virtual environment is activated.
Pick an agent type and start the server (each in its own terminal):
```powershell
uv run python a2a_server.py --agent-type invoice --port 5000
uv run python a2a_server.py --agent-type policy --port 5001
uv run python a2a_server.py --agent-type logistics --port 5002
```
You can run one agent or all three — each listens on its own port.
### 2. Run a Client
Once a server is running, use any of the client samples in [`samples/02-agents/a2a/`](../../02-agents/a2a/):
```powershell
cd python/samples/02-agents/a2a
$env:A2A_AGENT_HOST = "http://localhost:5001/"
uv run python agent_with_a2a.py
```