pub fn spend_summary(conn: &Connection, q: &SpendQuery) -> Result<Vec<SpendRow>>Expand description
Execute a validated spend query (DW-079): aggregate the ai_spend
table over a billing window, grouped by the requested dimensions.
Rows order by cost descending (the billing-relevant axis). Reads
the RAW ai_spend rows directly — spend is per-request, not
rolled up (the volume is orders of magnitude below the access
record path, and billing windows are short).