monthly_cap_exceeded - Five Nine

HTTP 403 · type permission. The key carries a monthly_cap_usd, and settled spend this calendar month (UTC) has reached it — or this request’s reservation would push past it. Caps are permissions, not rates: the refusal happens at reservation time, before anything runs. Nothing was charged.

The shape

{
  "error": {
    "type": "permission",
    "code": "monthly_cap_exceeded",
    "message": "This key's monthly cap is $100.00; $98.60 is already spent this month.",
    "doc_url": "https://docs.fiveninelabs.com/errors/monthly_cap_exceeded",
    "request_id": "req_3fp77b",
    "cap_usd": 100,
    "spent_usd": 98.6
  }
}

How to fix

Raise the key’s monthly cap in the dashboard, if you own that decision — or wait: the window is the calendar month in UTC, so it resets at 00:00 UTC on the 1st.
If this key belongs to one workload among several, mint separate keys with separate caps — the cap is per key, which is what makes it a budget boundary you can hand out.
Audit where the month went: GET /v1/usage?key=key_… pages the ledger, every settle citing the run whose signed receipts justify it.

Reproduce it

Set a throwaway key’s monthly cap to less than you’ve already spent with it this month (dashboard → Keys), then make any spending POST:

curl https://api.fiveninelabs.com/v1/sessions \
  -H "Authorization: Bearer $CAPPED_KEY" \
  -H "Content-Type: application/json" \
  -d '{"query": "vinyl records under $30", "max_spend_usd": 1}'