chore: Create an example for multi agent live streaming

This example include multi agents:
- Root agent.
- Sub agent for Rolling Dice.
- Sub agent for checking primes.

Added README.md to demonstrate how to use it.

PiperOrigin-RevId: 777599625

Author: hangfei

contributing/samples/live_bidi_streaming_agent/__init__.py renamed to contributing/samples/live_bidi_streaming_multi_agent/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import random
+
+from google.adk.agents import Agent
+from google.adk.examples.example import Example
+from google.adk.tools.example_tool import ExampleTool
+from google.genai import types
+
+
+# --- Roll Die Sub-Agent ---
+def roll_die(sides: int) -> int:
+  """Roll a die and return the rolled result."""
+  return random.randint(1, sides)
+
+
+roll_agent = Agent(
+    name="roll_agent",
+    description="Handles rolling dice of different sizes.",
+    instruction="""
+      You are responsible for rolling dice based on the user's request.
+      When asked to roll a die, you must call the roll_die tool with the number of sides as an integer.
+    """,
+    tools=[roll_die],
+    generate_content_config=types.GenerateContentConfig(
+        safety_settings=[
+            types.SafetySetting(  # avoid false alarm about rolling dice.
+                category=types.HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
+                threshold=types.HarmBlockThreshold.OFF,
+            ),
+        ]
+    ),
+)
+
+
+# --- Prime Check Sub-Agent ---
+def check_prime(nums: list[int]) -> str:
+  """Check if a given list of numbers are prime."""
+  primes = set()
+  for number in nums:
+    number = int(number)
+    if number <= 1:
+      continue
+    is_prime = True
+    for i in range(2, int(number**0.5) + 1):
+      if number % i == 0:
+        is_prime = False
+        break
+    if is_prime:
+      primes.add(number)
+  return (
+      "No prime numbers found."
+      if not primes
+      else f"{', '.join(str(num) for num in primes)} are prime numbers."
+  )
+
+
+prime_agent = Agent(
+    name="prime_agent",
+    description="Handles checking if numbers are prime.",
+    instruction="""
+      You are responsible for checking whether numbers are prime.
+      When asked to check primes, you must call the check_prime tool with a list of integers.
+      Never attempt to determine prime numbers manually.
+      Return the prime number results to the root agent.
+    """,
+    tools=[check_prime],
+    generate_content_config=types.GenerateContentConfig(
+        safety_settings=[
+            types.SafetySetting(  # avoid false alarm about rolling dice.
+                category=types.HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
+                threshold=types.HarmBlockThreshold.OFF,
+            ),
+        ]
+    ),
+)
+
+
+def get_current_weather(location: str):
+  """
+  Returns the current weather.
+  """
+  if location == "New York":
+    return "Sunny"
+  else:
+    return "Raining"
+
+
+root_agent = Agent(
+    # find supported models here: https://google.github.io/adk-docs/get-started/streaming/quickstart-streaming/
+    # model='gemini-live-2.5-flash-preview-native-audio',  # for Vertex project
+    model="gemini-live-2.5-flash-preview",  # for AI studio key
+    name="root_agent",
+    instruction="""
+      You are a helpful assistant that can check time, roll dice and check if numbers are prime.
+      You can check time on your own.
+      You delegate rolling dice tasks to the roll_agent and prime checking tasks to the prime_agent.
+      Follow these steps:
+      1. If the user asks to roll a die, delegate to the roll_agent.
+      2. If the user asks to check primes, delegate to the prime_agent.
+      3. If the user asks to roll a die and then check if the result is prime, call roll_agent first, then pass the result to prime_agent.
+      Always clarify the results before proceeding.
+    """,
+    global_instruction=(
+        "You are DicePrimeBot, ready to roll dice and check prime numbers."
+    ),
+    sub_agents=[roll_agent, prime_agent],
+    tools=[get_current_weather],
+    generate_content_config=types.GenerateContentConfig(
+        safety_settings=[
+            types.SafetySetting(  # avoid false alarm about rolling dice.
+                category=types.HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
+                threshold=types.HarmBlockThreshold.OFF,
+            ),
+        ]
+    ),
+)

contributing/samples/live_bidi_streaming_multi_agent/agent.py

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+# Simplistic Live (Bidi-Streaming) Multi-Agent
+This project provides a basic example of a live, bidirectional streaming multi-agent
+designed for testing and experimentation.
+
+You can see full documentation [here](https://google.github.io/adk-docs/streaming/).
+
+## Getting Started
+
+Follow these steps to get the agent up and running:
+
+1.  **Start the ADK Web Server**
+    Open your terminal, navigate to the root directory that contains the
+    `live_bidi_streaming_agent` folder, and execute the following command:
+    ```bash
+    adk web
+    ```
+
+2.  **Access the ADK Web UI**
+    Once the server is running, open your web browser and navigate to the URL
+    provided in the terminal (it will typically be `http://localhost:8000`).
+
+3.  **Select the Agent**
+    In the top-left corner of the ADK Web UI, use the dropdown menu to select
+    this agent.
+
+4.  **Start Streaming**
+    Click on either the **Audio** or **Video** icon located near the chat input
+    box to begin the streaming session.
+
+5.  **Interact with the Agent**
+    You can now begin talking to the agent, and it will respond in real-time.
+
+## Usage Notes
+
+* You only need to click the **Audio** or **Video** button once to initiate the
+ stream. The current version does not support stopping and restarting the stream
+  by clicking the button again during a session.
+
+## Sample Queries
+
+- Hello, what's the weather in Seattle and New York?
+- Could you roll a 6-sided dice for me?
+- Could you check if the number you rolled is a prime number or not?

contributing/samples/live_bidi_streaming_multi_agent/readme.md

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import agent