Required fields added in POST /v1/messages?beta=true (BetaRefusalStopDetails)

What changed

Required fields added in POST /v1/messages?beta=true (BetaRefusalStopDetails) Affected surface: POST /v1/messages?beta=true. Root cause: schema `BetaRefusalStopDetails`. Detected at Wed, 10 Jun 2026 02:23:03 UTC UTC.

Diff

{
  "added_required": [
    "fallback_credit_token",
    "fallback_has_prefill_claim",
    "recommended_model"
  ],
  "path": "POST /v1/messages?beta=true",
  "schema_path": "schema BetaRefusalStopDetails"
}

Likely impact

Existing integrations relying on this surface will fail or behave incorrectly. Treat this as a release-blocker until the recommended action below is applied.

Recommended action

Add the new required field to all request payloads or arguments. Requests omitting it will be rejected.