Type Alias MessageSender 

pub type MessageSender = Arc<dyn Fn(&str, &str) -> Result<bool, String> + Send + Sync>;

Function type for controller-aware delivery of a message to a (non-PTY) agent.

Given (block_id, message), returns:

• Ok(true) — delivered on the controller’s structured channel (persistent stream-json stdin / ACP session/prompt); no PTY keystrokes needed.
• Ok(false) — the controller is PTY-based; the caller should fall back to keystroke injection.
• Err(_) — a structured controller failed to accept the message (e.g. the persistent process is not running); the caller must NOT fall back to PTY, since such controllers reject raw keystrokes.

Aliased Type

pub struct MessageSender { /* private fields */ }