Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
SDKArea: what it touches
ImprovementsKind: in v2.1.223,
ImprovementsSection of the release
What
The result schema now spells out the scope of its accounting fields, so callers stop reading usage as a whole-session total.
Details
usage is described as "MAIN AGENT LOOP ONLY — excludes Task subagent, sidechain, and auxiliary model calls, and is per-turn in streaming-input sessions. Prefer modelUsage for token/cost accounting."
Both the success and error result schemas attach descriptions to total_cost_usd and modelUsage.
The cost text explains it is "Cumulative estimated cost in USD for this query() call", that a mid-session /clear resets the running total, and that it is "An estimate, not a billing statement."
Documentation only: no runtime numbers changed.
Evidence
An estimate, not a billing statement.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
