Function query_stream 

pub async fn query_stream(
    prompt: impl Into<String>,
    options: Option<ClaudeAgentOptions>,
) -> Result<Pin<Box<dyn Stream<Item = Result<Message>> + Send>>>

Query Claude Code with streaming responses for memory-efficient processing.

Unlike query() which collects all messages in memory before returning, this function returns a stream that yields messages as they arrive from Claude. This is more memory-efficient for large conversations and provides real-time message processing capabilities.

Note: This function does not support can_use_tool callbacks or hooks. For permission handling or hook support, use [ClaudeClient] instead.

Performance Comparison

• query(): O(n) memory usage, waits for all messages before returning
• query_stream(): O(1) memory per message, processes messages in real-time

Errors

Returns an error if:

• options.can_use_tool is set (use ClaudeClient instead)
• options.hooks is set (use ClaudeClient instead)
• Claude CLI cannot be found or started

Examples

use claude_agent_sdk_rs::{query_stream, Message, ContentBlock};
use futures::stream::StreamExt;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let mut stream = query_stream("What is 2 + 2?", None).await?;

    while let Some(result) = stream.next().await {
        match result? {
            Message::Assistant(msg) => {
                for block in &msg.message.content {
                    if let ContentBlock::Text(text) = block {
                        println!("Claude: {}", text.text);
                    }
                }
            }
            _ => {}
        }
    }

    Ok(())
}