// posts_scheduled_publish — cron TRIGGER (every minute). Flips due `scheduled`
// posts to `published`, which itself fires posts_on_publish -> notifications
// (a bounded trigger-fires-trigger chain).
let posts = docs::collection("posts");
let now = time::now();
let due = posts.find(#{
    status: "scheduled",
    publish_at: #{ "$lte": now },
    "$limit": 100,
});
let n = 0;
for r in due {
    let cur = r.data;
    cur.status = "published";
    posts.update(r.id, cur);
    n += 1;
}
if n > 0 { log::info("cron published scheduled posts", #{ count: n }); }