Cost tracking

Every agent turn's token usage and cost is recorded per tick, per role, and per issue (<issue_dir>/cost.json). cheaphelp status --costs shows the cumulative cost per issue, and each tick's summary in cheaphelp logs includes a cost breakdown line.

Set daily_budget_usd in config.json (default 0, meaning unlimited) to cap total spend per UTC day across all repos. As spend approaches the cap, cheaphelp posts a warning comment on the active issue at budget_warn_at (default 0.80) and again at 95%; once the cap is reached it posts an "exceeded" comment and stops dispatching new agent turns until the next day.

See Configuration for the daily_budget_usd and budget_warn_at JSON keys.