tkach 0.3.0

A provider-independent agent runtime for Rust with built-in tools
Documentation 
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use async_trait::async_trait;
use serde_json::{Value, json};
use tokio::process::Command;

use crate::error::ToolError;
use crate::tool::{Tool, ToolContext, ToolOutput};

/// Execute shell commands.
///
/// Honours `ctx.cancel`: if the token fires mid-execution, the spawned
/// child is dropped. Combined with `.kill_on_drop(true)`, that sends
/// `SIGKILL` to the child process so the shell doesn't linger.
pub struct Bash;

#[async_trait]
impl Tool for Bash {
    fn name(&self) -> &str {
        "bash"
    }

    fn description(&self) -> &str {
        "Execute a bash command and return its output (stdout + stderr). \
         The command runs in the agent's working directory."
    }

    fn input_schema(&self) -> Value {
        json!({
            "type": "object",
            "properties": {
                "command": {
                    "type": "string",
                    "description": "The shell command to execute"
                },
                "timeout_ms": {
                    "type": "integer",
                    "description": "Timeout in milliseconds. Default: 120000 (2 minutes)"
                }
            },
            "required": ["command"]
        })
    }

    async fn execute(&self, input: Value, ctx: &ToolContext) -> Result<ToolOutput, ToolError> {
        let command = input["command"]
            .as_str()
            .ok_or_else(|| ToolError::InvalidInput("command is required".into()))?;
        let timeout_ms = input["timeout_ms"].as_u64().unwrap_or(120_000);

        // kill_on_drop(true) ensures that dropping the spawned future (e.g.
        // when cancel fires) actually terminates the child instead of
        // leaking it behind the agent.
        let output_fut = Command::new("bash")
            .arg("-c")
            .arg(command)
            .current_dir(&ctx.working_dir)
            .kill_on_drop(true)
            .output();

        let timeout_fut =
            tokio::time::timeout(std::time::Duration::from_millis(timeout_ms), output_fut);

        tokio::select! {
            biased;
            _ = ctx.cancel.cancelled() => {
                // Dropping `timeout_fut` cascades into dropping the child,
                // which — thanks to kill_on_drop — terminates the process.
                Err(ToolError::Cancelled)
            }
            result = timeout_fut => match result {
                Ok(Ok(output)) => Ok(format_output(output)),
                Ok(Err(e)) => Err(ToolError::Io(e)),
                Err(_) => Ok(ToolOutput::error(format!(
                    "Command timed out after {timeout_ms}ms"
                ))),
            },
        }
    }
}

fn format_output(output: std::process::Output) -> ToolOutput {
    let stdout = String::from_utf8_lossy(&output.stdout);
    let stderr = String::from_utf8_lossy(&output.stderr);

    let mut result = String::new();
    if !stdout.is_empty() {
        result.push_str(&stdout);
    }
    if !stderr.is_empty() {
        if !result.is_empty() {
            result.push('\n');
        }
        result.push_str("[stderr]\n");
        result.push_str(&stderr);
    }

    if output.status.success() {
        ToolOutput::text(if result.is_empty() {
            "(no output)".to_string()
        } else {
            result
        })
    } else {
        let code = output.status.code().unwrap_or(-1);
        ToolOutput::error(format!("Exit code: {code}\n{result}"))
    }
}