//! Subagent spawning — launch a subagent on a background OS thread.
//!
//! Flow: creates a new tokio runtime on a dedicated OS thread, then
//! `block_on` the engine's `run_agent` future. Returns a
//! `JoinHandle<Result<String>>` the caller can `.join()`.

use std::thread;

use anyhow::Result;
use tracing::{info, instrument};

use crate::subagent::context::SubagentContext;
use crate::subagent::division::AccessTier;
use crate::subagent::engine::run_agent;
use crate::tools::ToolCtx;

/// Spawn a subagent on a background OS thread.
///
/// The subagent runs inside its own tokio runtime so it can make async calls
/// without blocking the calling thread's runtime.
///
/// Flow: `thread::spawn` → create `tokio::runtime::Runtime` →
/// `runtime.block_on(run_agent(...))` → return.
///
/// Returns a `JoinHandle` the caller can `join()` to await the result.
#[instrument(skip(ctx, tool_ctx))]
pub fn spawn_subagent(
    ctx: SubagentContext,
    directive: String,
    access: AccessTier,
    tool_ctx: ToolCtx,
) -> thread::JoinHandle<Result<String>> {
    info!("Spawning subagent: {directive}");
    thread::spawn(move || {
        let rt = tokio::runtime::Runtime::new()?;
        rt.block_on(run_agent(ctx, &directive, access, tool_ctx))
    })
}