diff --git a/samples/cli.py b/samples/cli.py
index 935834dd3..beff26aa9 100644
--- a/samples/cli.py
+++ b/samples/cli.py
@@ -73,7 +73,9 @@ async def main() -> None:
     )
     args = parser.parse_args()
 
-    config = ClientConfig()
+    config = ClientConfig(
+        grpc_channel_factory=grpc.aio.insecure_channel,
+    )
     if args.transport:
         config.supported_protocol_bindings = [args.transport]
 
diff --git a/samples/hello_world_agent.py b/samples/hello_world_agent.py
index 4c9e6f18a..a6e589ac0 100644
--- a/samples/hello_world_agent.py
+++ b/samples/hello_world_agent.py
@@ -1,3 +1,4 @@
+import argparse
 import asyncio
 import contextlib
 import logging
@@ -257,5 +258,18 @@ async def serve(
 
 if __name__ == '__main__':
     logging.basicConfig(level=logging.INFO)
+    parser = argparse.ArgumentParser(description='Sample A2A agent server')
+    parser.add_argument('--host', default='127.0.0.1')
+    parser.add_argument('--port', type=int, default=41241)
+    parser.add_argument('--grpc-port', type=int, default=50051)
+    parser.add_argument('--compat-grpc-port', type=int, default=50052)
+    args = parser.parse_args()
     with contextlib.suppress(KeyboardInterrupt):
-        asyncio.run(serve())
+        asyncio.run(
+            serve(
+                host=args.host,
+                port=args.port,
+                grpc_port=args.grpc_port,
+                compat_grpc_port=args.compat_grpc_port,
+            )
+        )
diff --git a/tests/integration/test_samples_smoke.py b/tests/integration/test_samples_smoke.py
new file mode 100644
index 000000000..fcb49a003
--- /dev/null
+++ b/tests/integration/test_samples_smoke.py
@@ -0,0 +1,134 @@
+"""End-to-end smoke test for `samples/hello_world_agent.py` and `samples/cli.py`.
+
+Boots the sample agent as a subprocess on free ports, then runs the sample CLI
+against it once per supported transport, asserting the expected greeting reply
+flows through.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import socket
+import sys
+
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import httpx
+import pytest
+import pytest_asyncio
+
+
+if TYPE_CHECKING:
+    from collections.abc import AsyncGenerator
+
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SAMPLES_DIR = REPO_ROOT / 'samples'
+AGENT_SCRIPT = SAMPLES_DIR / 'hello_world_agent.py'
+CLI_SCRIPT = SAMPLES_DIR / 'cli.py'
+
+STARTUP_TIMEOUT_S = 30.0
+CLI_TIMEOUT_S = 30.0
+EXPECTED_REPLY = 'Hello World! Nice to meet you!'
+
+
+def _free_port() -> int:
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+        sock.bind(('127.0.0.1', 0))
+        return sock.getsockname()[1]
+
+
+async def _wait_for_agent_card(url: str) -> None:
+    deadline = asyncio.get_running_loop().time() + STARTUP_TIMEOUT_S
+    async with httpx.AsyncClient(timeout=2.0) as client:
+        while asyncio.get_running_loop().time() < deadline:
+            try:
+                response = await client.get(url)
+                if response.status_code == 200:
+                    return
+            except httpx.RequestError:
+                pass
+            await asyncio.sleep(0.2)
+    raise TimeoutError(f'Agent did not become ready at {url}')
+
+
+@pytest_asyncio.fixture
+async def running_sample_agent() -> AsyncGenerator[str, None]:
+    """Start `hello_world_agent.py` as a subprocess on free ports."""
+    host = '127.0.0.1'
+    http_port = _free_port()
+    grpc_port = _free_port()
+    compat_grpc_port = _free_port()
+    base_url = f'http://{host}:{http_port}'
+
+    proc = await asyncio.create_subprocess_exec(
+        sys.executable,
+        str(AGENT_SCRIPT),
+        '--host',
+        host,
+        '--port',
+        str(http_port),
+        '--grpc-port',
+        str(grpc_port),
+        '--compat-grpc-port',
+        str(compat_grpc_port),
+        cwd=str(REPO_ROOT),
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.STDOUT,
+    )
+
+    try:
+        await _wait_for_agent_card(f'{base_url}/.well-known/agent-card.json')
+        yield base_url
+    finally:
+        if proc.returncode is None:
+            proc.terminate()
+            try:
+                await asyncio.wait_for(proc.wait(), timeout=10.0)
+            except asyncio.TimeoutError:
+                proc.kill()
+                await proc.wait()
+
+
+async def _run_cli(base_url: str, transport: str) -> str:
+    """Run `cli.py --transport <transport>`, send `hello`, return combined output."""
+    proc = await asyncio.create_subprocess_exec(
+        sys.executable,
+        str(CLI_SCRIPT),
+        '--url',
+        base_url,
+        '--transport',
+        transport,
+        cwd=str(REPO_ROOT),
+        stdin=asyncio.subprocess.PIPE,
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.STDOUT,
+    )
+    try:
+        stdout, _ = await asyncio.wait_for(
+            proc.communicate(b'hello\n/quit\n'),
+            timeout=CLI_TIMEOUT_S,
+        )
+    except asyncio.TimeoutError:
+        proc.kill()
+        await proc.wait()
+        raise
+    output = stdout.decode('utf-8', errors='replace')
+    assert proc.returncode == 0, (
+        f'CLI exited with {proc.returncode} for transport {transport!r}.\n'
+        f'Output:\n{output}'
+    )
+    return output
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize('transport', ['JSONRPC', 'HTTP+JSON', 'GRPC'])
+async def test_cli_against_sample_agent(
+    running_sample_agent: str, transport: str
+) -> None:
+    """The CLI should successfully exchange a greeting over each transport."""
+    output = await _run_cli(running_sample_agent, transport)
+
+    assert 'TASK_STATE_COMPLETED' in output, output
+    assert EXPECTED_REPLY in output, output