Function should_drop_self_loop 

pub fn should_drop_self_loop(sender: &str, self_handle: Option<&str>) -> bool

Defense-in-depth self-loop guard for the agent loop entry point.

Returns true when sender is recognizable as the bot’s own outbound identity on this channel and the agent loop should refuse to spawn a turn. Mirrors Channel::drop_self_messages’s normalization (strip leading @, case-insensitive) so the two layers agree on what “self” means; the agent-loop call is a fallback for channel impls that route around the SDK guard or that expose self-identity later in their lifecycle than the orchestrator’s check fires.