Function statusline_json 

pub fn statusline_json(report: &Report, plan_id: &str) -> String

ocuse statusline --json: the same numbers the template resolves, in one object — plan and period label, period/month spend, the two rolling windows, and the top model. Caps are the aggregate ceilings aggregate_cap uses for the template’s {…_pct}/{…_bar} placeholders (null when nothing is capped).