Python: Add requirements.txt and .env.example to the a2a/ sample for pip-based setup (#5510)

* Add requirements.txt and .env.example to a2a sample

Beginners following the a2a/ sample had no pip-based install path:
the directory lacked requirements.txt and .env.example, unlike every
other 04-hosting/ sample.

- Add requirements.txt with editable local package paths matching the
  pattern used in azure_functions/ and similar hosting samples
- Add .env.example documenting FOUNDRY_PROJECT_ENDPOINT, FOUNDRY_MODEL,
  and A2A_AGENT_HOST
- Update README Quick Start to cover both pip (.venv) and uv workflows

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

* Python: Add `requirements.txt` and `.env.example` to the `a2a/` sample for pip-based setup

Fixes #5395

* fix(a2a-sample): address PR review feedback for issue #5395

- Remove 'from repo root' wording from Option B uv heading in README
  to avoid contradicting the 'run from this directory' instruction
- Fix A2A_AGENT_HOST default in .env.example from 5001 to 5000 to match
  function-tools flow; add clarifying comments about port usage
- Add note for pip users explaining they can replace 'uv run python'
  with 'python' once the virtual environment is activated

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

* Address review feedback for #5395: Python: [Samples][Python] a2a/ sample missing requirements.txt — beginners cannot install dependencies

---------

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

python/packages/core/agent_framework/__init__.py

@@ -277,11 +277,11 @@ __all__ = [
     "USER_AGENT_TELEMETRY_DISABLED_ENV_VAR",
     "Agent",
     "AgentContext",
-    "AgentFrameworkException",
     "AgentEvalConverter",
     "AgentExecutor",
     "AgentExecutorRequest",
     "AgentExecutorResponse",
+    "AgentFrameworkException",
     "AgentMiddleware",
     "AgentMiddlewareLayer",
     "AgentMiddlewareTypes",

python/packages/core/tests/core/test_exceptions.py

@@ -2,8 +2,6 @@
 
 """Tests for AgentFrameworkException inner_exception handling."""
 
-import pytest
-
 from agent_framework import AgentFrameworkException
 
 

python/samples/01-get-started/05_functional_workflow_with_agents.py

@@ -37,6 +37,8 @@ async def poem_workflow(topic: str) -> str:
     poem = (await writer.run(f"Write a poem about: {topic}")).text
     review = (await reviewer.run(f"Review this poem: {poem}")).text
     return f"Poem:\n{poem}\n\nReview: {review}"
+
+
 # </create_workflow>
 
 

python/samples/01-get-started/06_functional_workflow_basics.py

@@ -36,6 +36,8 @@ async def text_workflow(text: str) -> str:
     """Uppercase the text, then reverse it."""
     upper = await to_upper_case(text)
     return await reverse_text(upper)
+
+
 # </create_workflow>
 
 

python/samples/04-hosting/a2a/.env.example

@@ -0,0 +1,8 @@
+# Azure AI Foundry Configuration (required for a2a_server.py and a2a_agent_as_function_tools.py)
+FOUNDRY_PROJECT_ENDPOINT=https://your-project.services.ai.azure.com/api/projects/your-project
+FOUNDRY_MODEL=gpt-4o
+
+# A2A Client Configuration (required for agent_with_a2a.py and a2a_agent_as_function_tools.py)
+# The function-tools flow uses http://localhost:5000/ in the sample docs/output.
+# Update this value if you start a different local A2A server instance on another port.
+A2A_AGENT_HOST=http://localhost:5000/

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

@@ -42,8 +42,33 @@ All commands below should be run from this directory:
 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 (e.g. `python a2a_server.py ...`). `uv` is not required once the virtual environment is activated.
+
 Pick an agent type and start the server (each in its own terminal):
 
 ```powershell

python/samples/04-hosting/a2a/agent_framework_to_a2a.py

@@ -51,7 +51,7 @@ if __name__ == "__main__":
     agent = Agent(
         client=OpenAIChatClient(),
         name="Europe Travel Agent",
-        instructions="You are a helpful Europe Travel Agent. You can help users search and book flights and hotels across Europe."
+        instructions="You are a helpful Europe Travel Agent. You can help users search and book flights and hotels across Europe.",
     )
 
     request_handler = DefaultRequestHandler(

python/samples/04-hosting/a2a/requirements.txt

@@ -0,0 +1,23 @@
+# Agent Framework packages
+# To use the deployed version, uncomment the lines below and comment out the local installation lines
+# agent-framework-a2a
+# agent-framework-foundry
+
+# Local installation (for development and testing)
+# Each package must be listed explicitly because pip doesn't resolve uv workspace sources.
+# Without explicit entries, pip would fetch transitive dependencies from PyPI instead of local source.
+-e ../../../packages/core  # Core framework - base dependency for all packages
+-e ../../../packages/foundry  # Foundry support - dependency for FoundryChatClient in a2a_server.py
+-e ../../../packages/a2a  # A2A integration - provides A2AAgent and a2a-sdk
+
+# Azure authentication
+azure-identity
+
+# A2A server runtime
+uvicorn
+
+# HTTP client used by A2A client samples
+httpx
+
+# Environment variable loading
+python-dotenv