//! Feeds the count of open (un-acked) todos into an OTEL gauge on a timer.
//! Todos arrive and leave between turns, so the per-turn record would
//! leave the series stale while the agent sleeps.

use std::sync::Arc;
use std::time::Duration;

use crate::todos::Todos;

/// Half the exporter's one-minute interval, so every export carries a
/// value at most one tick old.
const TICK: Duration = Duration::from_secs(30);

/// Background loop: record the open-todo count every [`TICK`]. Detached
/// task — runs for the harness's lifetime; read errors are logged, never
/// fatal.
pub async fn run(todos: Arc<Todos>) {
    loop {
        match todos.open_count() {
            Ok(n) => crate::otel_turn_metrics::record_open_todos(n),
            Err(e) => tracing::warn!(error = %e, "open todo count failed"),
        }
        tokio::time::sleep(TICK).await;
    }
}