Phase 28's in-game mail UI groups personal threads by the other
party's race. To support that without an extra membership-listing
RPC, the diplomail subsystem now:
- accepts `recipient_race_name` on `POST /messages` and
`POST /admin` (target=user) as an alternative to
`recipient_user_id`; the service resolves it via the existing
`Memberships.ListMembers(gameID, "active")` and rejects with
`forbidden` when the matching member is no longer active;
- snapshots `diplomail_messages.sender_race_name` at send time for
every player sender (admin / system rows stay NULL). The UI keys
per-race threading on this column.
Schema, openapi, README, and a focused e2e test for the new path
(happy path + dual / missing / unknown / kicked errors) land in
this commit; the gateway + UI legs follow in subsequent commits on
this branch.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Ilia Denisov
7b43ce5844