chore: import upstream snapshot with attribution

python/samples/04-hosting/a2a/README.md

@@ -0,0 +1,94 @@
+# 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
+```
+
+## Security considerations for multi-tenant hosting
+
+The default `a2a-sdk` task/push-config stores scope ownership by `user_name` only. **Any host that mounts tenant-bearing routes must pass a tenant-aware `owner_resolver`** to the stores, e.g.:
+
+```python
+from a2a.server.tasks import InMemoryTaskStore
+
+def resolve_tenant_user_scope(context):
+    # Derive tenant + user identity from your host's auth/session context.
+    return f"{context.tenant}:{context.user.user_name}"
+task_store = InMemoryTaskStore(owner_resolver=resolve_tenant_user_scope)
+```