Function execute_loop 

pub async fn execute_loop<F>(
    executor: Arc<dyn AgentExecutor>,
    initial: Vec<AgentStepSpec>,
    max_iterations: usize,
    event_tx: Option<Sender<AgentEvent>>,
    next: F,
) -> Vec<StepOutcome>
where
    F: FnMut(&[StepOutcome]) -> LoopDecision + Send,

Run rounds until the predicate says Stop, a round is asked to run no specs, or max_iterations is reached — whichever comes first. Each round is a barrier (execute_steps_parallel); next receives the just-completed round’s outcomes and decides whether (and with what) to continue. Returns the last round’s outcomes (empty if initial was empty).

max_iterations is mandatory and a hard cap: it is clamped to at least 1, and once reached the loop stops even if the predicate returns Continue. This is the guard that makes an LLM-driven, unknown-length loop (e.g. loop-until-dry) safe — the predicate must never be the only termination condition.

This is the “loop” shape from the orchestration grammar; like the other combinators it is written purely against the AgentExecutor seam and adds no scheduling of its own.