Usage & billing dashboard: per-key usage vs quota (green/amber/red), the account's spend-cap status, an in-context 402 upgrade prompt when either is exhausted, and the 80%-quota expansion nudge -- every number read off the same meter enforced at request time. Not billable: reading the dashboard must never itself cost quota.

free_tier reports the free allowance and how much of it this billing month has spent (null for an account holding no free key, which neither free wall can bind). blocked_deliveries counts the changes we DECIDED not to send you since that period began, per reason: wall_blocked is the free monthly change allowance, cap_blocked is your own spend cap. Both are terminal and are never retried, so a non-zero count is why a watch has gone quiet -- as distinct from nobody hiring.