Build and manage a Custom Audience via the X Ads API v4 Audience API

Steps

1. Confirm allowlist access to the Audience endpoint (requires a form submission and acceptance of the X Ads Products and Services Agreement) before calling any audience endpoints.
2. Create an audience shell with POST custom_audience and capture the returned custom_audience id.
3. Add users with POST accounts/:account_id/custom_audiences/:custom_audience_id/users, setting operation_type to Update and providing a users array where each user object can carry multiple hashed identifier keys (email, handle, twitter_id).
4. Remove users from the same endpoint by setting operation_type to Delete, matching on any key that was present when the user was added.
5. Batch adds and removes for the same audience within a single request using multiple operation_type entries, and call in near-real-time incremental batches rather than re-sending full audience membership each time.