Upload a hashed customer list to build a Snapchat Customer Lists audience

Steps

1. Create an audience segment: POST /v1/adaccounts/{ad_account_id}/segments with source_type FIRST_PARTY.
2. Normalize identifiers before hashing: trim and lowercase emails, and strip leading zeros and non-digit characters from phone numbers while including the country code.
3. Hash each normalized value with SHA-256 and lowercase-hex encode it.
4. POST /v1/segments/{segment_id}/users with schema set to one identifier type (e.g. EMAIL_SHA256) and data as the array of hashes — one schema type per request.
5. Poll the segment's upload_status and targetable_status fields until targetable_status reports READY before using it for targeting.
6. Use DELETE on the same endpoint to remove specific users, or DELETE /segments/{segment_id}/all_users to clear the whole list.