Upserts up to 1000 accounts (SSO users and anonymous users) and returns the uuid (preference secret) assigned to each. Use this to seed the Preferences Centre with users imported from another system, or to fetch existing secrets for accounts you already know about.

Body fields - exactly one of userId or email per entry

• userId - existing SSO account numeric ID. Treated as a non-anonymous account.
• email - email address. Treated as an anonymous account. The service creates or finds an anonymous user for this email.
• uuid (optional) - the preference secret you want the account to use. If omitted, the service generates one. If provided and differs from the stored value, the stored secret is replaced.

Providing both userId and email, or neither, returns 400 Bad Request for the whole batch.

Response

Returns the same array you sent, with uuid (and userId/email for anonymous upserts) populated, plus an optional error field per row on failure.