Function set_at 

pub(crate) fn set_at(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    uid: &str,
    at: &str,
    minutes: u32,
) -> String

A task pinned to a time (“2026-10-06T14:30”, your time zone) for minutes (0: as long as its block is, else what the plan lays for it), or left to the plan again (“”): its time block, an event, made, moved or taken away (blocks); its own dates stay as set (docs/tasks.md, “The plan proposes; your dates stay yours”, “Pinned to a time”); the day is laid again at once, and “Undo” offered for ten seconds. Returns what went wrong, else “”.