Implement streaming

[dicksontsai]

1. Refactored query() out of src/claude_code_sdk/__init__.py
2. Refactored parse_message() out of src/claude_code_sdk/_internal/client.py
3. Added src/claude_code_sdk/client.py
4. Added examples and tests

[wolffiex]

Code Review

Great implementation of streaming capabilities! The bidirectional streaming API is well-designed with clear separation between query() for simple use cases and ClaudeSDKClient for interactive sessions.

Key strengths:

• Clean API design with two distinct modes
• Good async/await patterns throughout
• Comprehensive test coverage
• Helpful examples

Areas for improvement:

1. JSON Error Handling

• JSON parsing errors are silently ignored in subprocess_cli.py:294
• No error handling for missing keys in message_parser.py
• Inconsistent use of .get() vs direct key access

2. Parameter Naming Inconsistencies

• connect() uses 'prompt' while send_message() uses 'content'
• 'prompt' is confusing for AsyncIterable of messages
• Should be consistent across the API

3. Resource Management

• Hardcoded timeouts (30s for control requests)
• Fixed memory limits not configurable
• No backpressure handling

4. API Clarity

• receive_response() stopping behavior could be clearer
• send_message() only accepts strings vs structured messages in connect()

Overall, this is a solid foundation that would benefit from addressing these consistency and robustness issues.

[dicksontsai]

Addressing feedback:

JSON parsing errors are silently ignored in subprocess_cli.py:294

The existing code in subprocess_cli.py:294 tries to decode a buffer until it encounters a valid JSON object, so silently ignoring JSON decoding errors is intentional. This PR maintains this behavior for backward compatibility.

No error handling for missing keys in message_parser.py
Inconsistent use of .get() vs direct key access

Added KeyError checking in message_parser.py to match the Typescript SDK. All direct key accesses are now wrapped.

connect() uses 'prompt' while send_message() uses 'content'
'prompt' is confusing for AsyncIterable of messages
Should be consistent across the API

Renamed ClaudeSDKClient.send_message() to ClaudeSDKClient.query(), and named the parameter prompt across ClaudeSDKClient.connect(), ClaudeSDKClient.query(), and query(). I stick with prompt because that's what the Typescript SDK uses.

3. Resource Management
   Hardcoded timeouts (30s for control requests)

Fixed

Fixed memory limits not configurable
No backpressure handling

Let's address this in a separate PR. This PR should focus on providing a new way to feed input into Claude Code SDK via streaming. I believe the "fixed memory limits" and "backpressure" issues refer to the output stream, which this PR should ideally not touch.

4. API Clarity
   receive_response() stopping behavior could be clearer

Fixed

send_message() only accepts strings vs structured messages in connect()

Fixed