Replace the spend caps for one member of your organization. The body is the full desired state for both periods: caps you include are created or updated, and caps you omit are removed. Both monthly and daily are required, so a body that leaves one out is rejected rather than treated as a partial update. Send {"monthly": {}, "daily": {}} to clear every cap for the user. The response is the resulting state, in the same form GET returns.

Rules, identical to the Settings → Usage editor:

• model_key must be a canonical ledger model key (lowercase, no provider prefix), e.g. claude-sonnet-4.
• Within a period, a per-model cap cannot exceed that period's overall limit_amount when one is set.
• At most 50 per-model caps per period, with no duplicate model keys.
• Amounts are nonnegative and support at most 4 decimal places.

Each created, changed, or removed cap is recorded in the audit log as usage_policy.created, usage_policy.updated, or usage_policy.deleted, attributed to the API key or OAuth client that made the call. Caps that were sent unchanged are not re-recorded.

API keys are not scoped: any key for your organization can raise, lower, or remove any member's caps, exactly as an administrator can in Settings. Treat keys that call this endpoint accordingly.

Returns 404 if the user is not an active member of your organization, 409 if the body sets a cap while your organization has no billing profile yet (caps are denominated in the billing currency; a body that only clears caps succeeds), 400 when the body breaks one of the rules above, and 500 with Failed to record audit trail. if the audit trail for the change could not be written (the limits were not changed).