feat: Enforce Task or Message as an initial response for Send Streaming Message

samples/README.md

@@ -0,0 +1,60 @@
+# A2A Python SDK — Samples
+
+This directory contains runnable examples demonstrating how to build and interact with an A2A-compliant agent using the Python SDK.
+
+## Contents
+
+| File | Role | Description |
+|---|---|---|
+| `hello_world_agent.py` | **Server** | A2A agent server |
+| `cli.py` | **Client** | Interactive terminal client |
+
+The samples are designed to work together out of the box: the agent listens on `http://127.0.0.1:41241`, which is the default URL used by the client.
+---
+
+## `hello_world_agent.py` — Agent Server
+
+Implements an A2A agent that responds to simple greeting messages (e.g., "hello", "how are you", "bye") with text replies, simulating a 1-second processing delay.
+
+Demonstrates:
+- Subclassing `AgentExecutor` and implementing `execute()` / `cancel()`
+- Publishing streaming status updates and artifacts via `TaskUpdater`
+- Exposing all three transports in both protocol versions (v1.0 and v0.3 compat) simultaneously:
+  - **JSON-RPC** (v1.0 and v0.3) at `http://127.0.0.1:41241/a2a/jsonrpc`
+  - **HTTP+JSON (REST)** (v1.0 and v0.3) at `http://127.0.0.1:41241/a2a/rest`
+  - **gRPC v1.0** on port `50051`
+  - **gRPC v0.3 (compat)** on port `50052`
+- Serving the agent card at `http://127.0.0.1:41241/.well-known/agent-card.json`
+
+**Run:**
+
+```bash
+uv run python samples/hello_world_agent.py
+```
+
+---
+
+## `cli.py` — Client
+
+An interactive terminal client with full visibility into the streaming event flow. Each `TaskStatusUpdate` and `TaskArtifactUpdate` event is printed as it arrives.
+
+Features:
+- Transport selection via `--transport` flag (`JSONRPC`, `HTTP+JSON`, `GRPC`)
+- Session management (`context_id` persisted across messages, `task_id` per task)
+- Graceful error handling for HTTP and gRPC failures
+
+**Run:**
+
+```bash
+# Connect to the local hello_world_agent (default):
+uv run python samples/cli.py
+
+# Connect to a different URL, using gRPC:
+uv run python samples/cli.py --url http://192.168.1.10:41241 --transport GRPC
+```
+
+Then type a message like `hello` and press Enter.
+
+Type `/quit` or `/exit` to stop, or press `Ctrl+C`.
+
+

samples/cli.py

@@ -11,25 +11,22 @@
 
 from a2a.client import A2ACardResolver, ClientConfig, create_client
 from a2a.types import Message, Part, Role, SendMessageRequest, TaskState
+from a2a.utils import get_artifact_text, get_message_text
 
 
 async def _handle_stream(
     stream: Any, current_task_id: str | None
 ) -> str | None:
-    async for event, task in stream:
-        if not task:
-            continue
+    async for event in stream:
         if not current_task_id:
-            current_task_id = task.id
-
+            current_task_id = event.task.id
         if event:
             if event.HasField('status_update'):
                 state_name = TaskState.Name(event.status_update.status.state)
                 print(f'TaskStatusUpdate [state={state_name}]:', end=' ')
                 if event.status_update.status.HasField('message'):
-                    for part in event.status_update.status.message.parts:
-                        if part.text:
-                            print(part.text, end=' ')
+                    message = event.status_update.status.message
+                    print(get_message_text(message, delimiter=' '))
                 print()
 
                 if (
@@ -44,9 +41,11 @@ async def _handle_stream(
                     f'TaskArtifactUpdate [name={event.artifact_update.artifact.name}]:',
                     end=' ',
                 )
-                for part in event.artifact_update.artifact.parts:
-                    if part.text:
-                        print(part.text, end=' ')
+                print(
+                    get_artifact_text(
+                        event.artifact_update.artifact, delimiter=' '
+                    )
+                )
                 print()
 
     return current_task_id
@@ -68,6 +67,8 @@ async def main() -> None:
     config = ClientConfig()
     if args.transport:
         config.supported_protocol_bindings = [args.transport]
+    if args.transport == 'GRPC':
+        config.grpc_channel_factory = grpc.aio.insecure_channel
 
     print(
         f'Connecting to {args.url} (preferred transport: {args.transport or "Any"})'