Function attach_program 

pub async fn attach_program(
    state: &Arc<ServerState>,
    program_path: &str,
) -> Result<Value, ErrorEnvelope>

Attach a program. The active-program + canon commit happens ATOMICALLY inside the engine under the worker lock (via commit_attach_if_needed) — NOT here (R2 seat-C). This wrapper only supplies the poison-key selector and runs the same crash/respawn engine (§4.3).