Create a lead

Creates a lead, or adds an existing lead to the requested lists. When an email matches a lead already on your team, the request is additive: it adds only the missing list memberships and returns 201 rather than an email duplicate error. When the matched lead belongs to a teammate, the request still adds it to your lists, and the teammate's lead itself is only updated if you have permission to edit it. A request without an email is never matched by email — it does not reuse an existing email-less lead — though a lead with an identical name, company, and list is still rejected as a duplicate.

Accepts department since HUN-23171, normalized to its canonical key so a localized display label ("Sales") is stored as sales. Lead attributes are not modelled field-by-field in this contract yet — the response uses the generic resource envelope — so this note is where the accepted set is recorded.

When another request is creating leads for the team, returns 409 with lead_creation_in_progress and Retry-After: 1. Retry the request after one second.