Add message-level streaming support with query_stream()

[terasakisatoshi]

Summary

• Adds new query_stream() function for message-level streaming
• Enables more responsive applications by yielding messages as they arrive
• Includes comprehensive examples demonstrating streaming usage

Details

This PR introduces streaming support to ClaudeCodeSDK.jl, allowing applications to receive and process messages as they arrive from the Claude CLI rather than waiting for the complete response.

Key Changes

1. New query_stream() function: Returns a Channel{Message} that yields messages as they're received
2. Transport layer enhancement: Added stream_messages() that reads CLI output line-by-line
3. Client streaming support: New process_query_stream() method to handle streaming workflow
4. Example code: Three new examples demonstrating different streaming use cases

Important Note

This implementation provides message-level streaming, not character-level streaming. The Claude CLI outputs complete messages as JSON objects, so we receive:

• SystemMessage immediately when the query starts
• Complete AssistantMessage once Claude finishes generating it
• ResultMessage when the query completes

This is still valuable for:

• Long-running queries where you want immediate feedback
• Applications that need to know when processing starts
• Better UX with progress indication

Usage Example

using ClaudeCodeSDK

# Stream messages as they arrive
for message in query_stream(prompt="Write a detailed analysis")
    if message isa SystemMessage
        println("Query started...")
    elseif message isa AssistantMessage
        for block in message.content
            if block isa TextBlock
                print(block.text)
                flush(stdout)
            end
        end
    elseif message isa ResultMessage
        println("\nCompleted! Cost: \$$(message.cost_usd)")
    end
end

Testing

All existing tests pass. The streaming functionality gracefully handles CLI availability and provides the same error handling as the batch query() function.

🤖 Generated with Claude Code