fix: update links to the sample code and other minor fixes

fix: update links to the sample code and other minor fixes

Author: kazunori279

docs/streaming/dev-guide/part1.md

@@ -410,11 +410,15 @@ In the following sections, you'll see each phase detailed, showing exactly when
 
 These components are created once when your application starts and shared across all streaming sessions. They define your agent's capabilities, manage conversation history, and orchestrate the streaming execution.
 
+!!! info "Python Version Requirement"
+
+    ADK requires **Python 3.10 or higher**. As of ADK v1.19.0, Python 3.9 is no longer supported. Ensure your development and production environments meet this requirement before installing ADK.
+
 #### Define Your Agent
 
 The `Agent` is the core of your streaming application—it defines what your AI can do, how it should behave, and which AI model powers it. You configure your agent with a specific model, tools it can use (like Google Search or custom APIs), and instructions that shape its personality and behavior.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/google_search_agent/agent.py#L10-L15" target="_blank">agent.py:10-15</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/google_search_agent/agent.py#L10-L15" target="_blank">agent.py:10-15</a>'
 """Google Search Agent definition for ADK Bidi-streaming demo."""
 
 import os
@@ -448,7 +452,7 @@ The ADK [Session](https://google.github.io/adk-docs/sessions/session/) manages c
 
 To create a `Session`, or get an existing one for a specified `session_id`, every ADK application needs to have a [SessionService](https://google.github.io/adk-docs/sessions/session/#managing-sessions-with-a-sessionservice). For development purpose, ADK provides a simple `InMemorySessionService` that will lose the `Session` state when the application shuts down.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L46" target="_blank">main.py:46</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L37" target="_blank">main.py:37</a>'
 from google.adk.sessions import InMemorySessionService
 
 # Define your session service
@@ -457,11 +461,18 @@ session_service = InMemorySessionService()
 
 For production applications, choose a persistent session service based on your infrastructure:
 
+**Use `SqliteSessionService` if:**
+
+- You need lightweight local persistence without external dependencies
+- You're building a single-server application or development environment
+- You want automatic database initialization with minimal configuration
+- Example: `SqliteSessionService(db_path="sessions.db")`
+
 **Use `DatabaseSessionService` if:**
 
-- You have existing PostgreSQL/MySQL/SQLite infrastructure
+- You have existing PostgreSQL/MySQL infrastructure
 - You need full control over data storage and backups
-- You're running outside Google Cloud or in hybrid environments
+- You're running multi-server deployments requiring shared state
 - Example: `DatabaseSessionService(connection_string="postgresql://...")`
 
 **Use `VertexAiSessionService` if:**
@@ -471,13 +482,13 @@ For production applications, choose a persistent session service based on your i
 - You need tight integration with Vertex AI features
 - Example: `VertexAiSessionService(project="my-project")`
 
-Both provide the same session persistence capabilities—choose based on your infrastructure. With persistent session services, the state of the `Session` will be preserved even after application shutdown. See the [ADK Session Management documentation](https://google.github.io/adk-docs/sessions/ for more details.
+All three provide session persistence capabilities—choose based on your infrastructure and scale requirements. With persistent session services, the state of the `Session` will be preserved even after application shutdown. See the [ADK Session Management documentation](https://google.github.io/adk-docs/sessions/ for more details.
 
 #### Define Your Runner
 
 The [Runner](https://google.github.io/adk-docs/runtime/) provides the runtime for the `Agent`. It manages the conversation flow, coordinates tool execution, handles events, and integrates with session storage. You create one runner instance at application startup and reuse it for all streaming sessions.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L34" target="_blank">main.py:34,49-53</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L50" target="_blank">main.py:50,53</a>'
 from google.adk.runners import Runner
 
 APP_NAME = "bidi-demo"
@@ -533,7 +544,7 @@ This design enables scenarios like:
 
 The recommended production pattern is to check if a session exists first, then create it only if needed. This approach safely handles both new sessions and conversation resumption:
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L110-L121" target="_blank">main.py:110-121</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L127-L133" target="_blank">main.py:127-133</a>'
 # Get or create session (handles both new sessions and reconnections)
 session = await session_service.get_session(
     app_name=APP_NAME,
@@ -560,7 +571,7 @@ This pattern works correctly in all scenarios:
 
 [RunConfig](part4.md) defines the streaming behavior for this specific session—which modalities to use (text or audio), whether to enable transcription, voice activity detection, proactivity, and other advanced features.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L89-L95" target="_blank">main.py:89-95</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L98-L104" target="_blank">main.py:98-104</a>'
 from google.adk.agents.run_config import RunConfig, StreamingMode
 from google.genai import types
 
@@ -581,7 +592,7 @@ run_config = RunConfig(
 
 `LiveRequestQueue` is the communication channel for sending messages to the agent during streaming. It's a thread-safe async queue that buffers user messages (text content, audio blobs, activity signals) for orderly processing.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L123" target="_blank">main.py:123</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L135" target="_blank">main.py:135</a>'
 from google.adk.agents.live_request_queue import LiveRequestQueue
 
 live_request_queue = LiveRequestQueue()
@@ -603,7 +614,7 @@ Once the streaming loop is running, you can send messages to the agent and recei
 
 Use `LiveRequestQueue` methods to send different types of messages to the agent during the streaming session:
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L136-L176" target="_blank">main.py:136-176</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L141-L189" target="_blank">main.py:141-189</a>'
 from google.genai import types
 
 # Send text content
@@ -626,7 +637,7 @@ See [Part 2: Sending messages with LiveRequestQueue](part2.md) for detailed API
 
 The `run_live()` async generator continuously yields `Event` objects as the agent processes input and generates responses. Each event represents a discrete occurrence—partial text generation, audio chunks, tool execution, transcription, interruption, or turn completion.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L178-L190" target="_blank">main.py:178-190</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L191-L206" target="_blank">main.py:191-206</a>'
 async for event in runner.run_live(
     user_id=user_id,
     session_id=session_id,
@@ -649,7 +660,7 @@ When the streaming session should end (user disconnects, conversation completes,
 
 Send a close signal through the queue to terminate the streaming loop:
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L213" target="_blank">main.py:213</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L225" target="_blank">main.py:225</a>'
 live_request_queue.close()
 ```
 
@@ -661,7 +672,7 @@ Here's a complete FastAPI WebSocket application showing all four phases integrat
 
 !!! note "Complete Demo Implementation"
 
-    For the production-ready implementation with multimodal support (text, audio, image), see the complete [`main.py`](https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py) file.
+    For the production-ready implementation with multimodal support (text, audio, image), see the complete [`main.py`](https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py) file.
 
 **Complete Implementation:**
 
@@ -795,7 +806,7 @@ async def websocket_endpoint(websocket: WebSocket, user_id: str, session_id: str
 
 The upstream task continuously receives messages from the WebSocket client and forwards them to the `LiveRequestQueue`. This enables the user to send messages to the agent at any time, even while the agent is generating a response.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L129-L176" target="_blank">main.py:129-176</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L141-L189" target="_blank">main.py:141-189</a>'
 async def upstream_task() -> None:
     """Receives messages from WebSocket and sends to LiveRequestQueue."""
     try:
@@ -811,7 +822,7 @@ async def upstream_task() -> None:
 
 The downstream task continuously receives `Event` objects from `run_live()` and sends them to the WebSocket client. This streams the agent's responses, tool executions, transcriptions, and other events to the user in real-time.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L178-L190" target="_blank">main.py:178-190</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L191-L206" target="_blank">main.py:191-206</a>'
 async def downstream_task() -> None:
     """Receives Events from run_live() and sends to WebSocket."""
     async for event in runner.run_live(
@@ -829,7 +840,7 @@ async def downstream_task() -> None:
 
 Both tasks run concurrently using `asyncio.gather()`, enabling true Bidi-streaming. The `try/finally` block ensures `LiveRequestQueue.close()` is called even if exceptions occur, minimizing the session resource usage.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L195-L213" target="_blank">main.py:195-213</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L210-L225" target="_blank">main.py:210-225</a>'
 try:
     await asyncio.gather(
         upstream_task(),
@@ -855,7 +866,7 @@ This example shows the core pattern. For production applications, consider:
 - **Authentication and authorization**: Implement authentication and authorization for your endpoints
 - **Rate limiting and quotas**: Add rate limiting and timeout controls. For guidance on concurrent sessions and quota management, see [Part 4: Concurrent Live API Sessions and Quota Management](part4.md#concurrent-live-api-sessions-and-quota-management).
 - **Structured logging**: Use structured logging for debugging.
-- **Persistent session services**: Consider using persistent session services (`DatabaseSessionService` or `VertexAiSessionService`). See the [ADK Session Services documentation](https://google.github.io/adk-docs/sessions/) for more details.
+- **Persistent session services**: Consider using persistent session services (`SqliteSessionService`, `DatabaseSessionService`, or `VertexAiSessionService`). See the [ADK Session Services documentation](https://google.github.io/adk-docs/sessions/) for more details.
 
 ## 1.6 What We Will Learn
 

docs/streaming/dev-guide/part2.md

@@ -73,7 +73,7 @@ graph LR
 
 The `send_content()` method sends text messages in turn-by-turn mode, where each message represents a discrete conversation turn. This signals a complete turn to the model, triggering immediate response generation.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L157-L158" target="_blank">main.py:157-158</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L166-L171" target="_blank">main.py:166-171</a>'
 content = types.Content(parts=[types.Part(text=json_message["text"])])
 live_request_queue.send_content(content)
 ```
@@ -103,7 +103,7 @@ For Live API, multimodal inputs (audio/video) use different mechanisms (see `sen
 
 The `send_realtime()` method sends binary data streams—primarily audio, image and video—flow through the `Blob` type, which handles transmission in realtime mode. Unlike text content that gets processed in turn-by-turn mode, blobs are designed for continuous streaming scenarios where data arrives in chunks. You provide raw bytes, and Pydantic automatically handles base64 encoding during JSON serialization for safe network transmission (configured in `LiveRequest.model_config`). The MIME type helps the model understand the content format.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L141-L145" target="_blank">main.py:141-145</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L153-L156" target="_blank">main.py:153-156</a>'
 audio_blob = types.Blob(
     mime_type="audio/pcm;rate=16000",
     data=audio_data
@@ -163,7 +163,7 @@ The `close` signal provides graceful termination semantics for streaming session
 
 See [Part 4: Understanding RunConfig](part4.md#streamingmode-bidi-or-sse) for detailed comparison and when to use each mode.
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L195-L213" target="_blank">main.py:195-213</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L210-L225" target="_blank">main.py:210-225</a>'
 try:
     logger.debug("Starting asyncio.gather for upstream and downstream tasks")
     await asyncio.gather(
@@ -199,7 +199,7 @@ Understanding how `LiveRequestQueue` handles concurrency is essential for buildi
 
 **Why synchronous send methods?** Convenience and simplicity. You can call them from anywhere in your async code without `await`:
 
-```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/main/python/agents/bidi-demo/app/main.py#L129-L158" target="_blank">main.py:129-158</a>'
+```python title='Demo implementation: <a href="https://github.com/google/adk-samples/blob/4274c70ae3f4c68595f543ee504474747ea9f0da/python/agents/bidi-demo/app/main.py#L141-L171" target="_blank">main.py:141-171</a>'
 async def upstream_task() -> None:
     """Receives messages from WebSocket and sends to LiveRequestQueue."""
     while True: