Verify a branded guest authentication challenge

POST /v1/developer/guest-auth/challenges/{challengeId}/verify

Operation ID: verifyDeveloperGuestAuth

Consumes a single-use challenge only from a branded host authorized through Collection.authorizedDomains, binds the proven Guest and canonical GuestProfile to the same kidSid, and returns guest session tokens to the host BFF. The BFF must set its own branded HttpOnly cookie; Kismet credentials and tokens must never enter browser JavaScript.

Contract status

Field	Value
Maturity	`beta`
Required capability	`guest_auth.write`
Freshness class	`sandbox-write`
Quota cost	`1`
Operational owner	Identity + Developer Experience

All operations require a Kismet Developer Bearer credential. Collection and resource authority is resolved from the credential’s installation grants; identifiers in the URL never grant access.

Request parameters

Name	In	Type	Required	Description
`challengeId`	path	string	yes
`x-kismet-csrf`	header	string	yes	Opaque CSRF proof validated by the same-origin host BFF before it calls Kismet. Never a Kismet credential.
`origin`	header	string	no	Original branded browser origin forwarded by the same-origin BFF. Must match Collection.authorizedDomains.
`x-forwarded-host`	header	string	no	Original branded host fallback for server route handlers that do not forward Origin. Must match Collection.authorizedDomains.

Request body

The request body is JSON. The canonical schema is:

{
  "type": "object",
  "additionalProperties": false,
  "required": [
    "code",
    "kidSid"
  ],
  "properties": {
    "code": {
      "type": "string",
      "pattern": "^\\d{6}$"
    },
    "kidSid": {
      "type": "string",
      "pattern": "^kid_[A-Za-z0-9]{8}$"
    }
  }
}

Minimal example:

{
  "code": "042817",
  "kidSid": "kid_Ab12Cd34"
}

cURL

curl --request POST \
  "$KISMET_API_ORIGIN/v1/developer/guest-auth/challenges/CHALLENGE_ID/verify" \
  --header "Authorization: Bearer $KISMET_DEVELOPER_API_KEY" \
  --header "Accept: application/json" \
  --header "Content-Type: application/json" \
  --data '{"code":"042817","kidSid":"kid_Ab12Cd34"}'

Responses

Status	Meaning
200	Success.
400	Invalid request parameters or body.
401	Missing, invalid, expired, or inappropriate credential/session.
403	Credential lacks the required grant/capability, or an origin/CSRF check failed.
409	Request conflicts with the installation environment or current state.
410	The single-use authentication challenge is no longer valid.
429	Rate limit or quota exceeded; inspect response metadata before retrying.
503	A required Kismet dependency is temporarily unavailable.

Success example

{
  "kidSid": "kid_AbCdEf12",
  "guest": {
    "id": "77777777-7777-4777-8777-777777777777",
    "email": "developer-test@example.com",
    "guestProfileId": "88888888-8888-4888-8888-888888888888"
  },
  "session": {
    "accessToken": "<server-only-access-token>",
    "refreshToken": "<server-only-refresh-token>",
    "expiresAt": "2026-09-17T18:00:00.000Z"
  }
}