4 changed files with 191 additions and 2 deletions
@@ -1270,6 +1270,20 @@ The message detail response includes both the original body and,
 when available, the cached translation; the client UI defaults to
 the translated text and offers a "show original" toggle.

+The in-game UI groups personal mail into per-race threads — every
+personal message exchanged between the local player and another
+race lands in one thread keyed on the other party's race. System
+mail, admin notifications, and the player's own paid-tier
+broadcasts render as stand-alone entries in the same list pane and
+are never threaded. `read_at` and `deleted_at` drive the local
+unread counter and the soft-delete affordance but are not surfaced
+to the user — diplomatic mail does not promise read receipts. The
+compose form picks the recipient by race name (resolved
+server-side from `Memberships.ListMembers(game_id, "active")`); no
+client-side memberships listing is fetched. See
+[`ui/docs/diplomail-ui.md`](../ui/docs/diplomail-ui.md) for the
+detailed UI breakdown.
+
 ### 11.5 Lifecycle hooks

 Three lobby transitions land as system mail in the affected
@@ -1309,6 +1309,20 @@ bulk-purge всей почты соответствующей партии.
 кэш) перевод; UI по умолчанию показывает перевод и предлагает
 переключение «показать оригинал».

+Внутриигровой UI группирует личную почту по веткам по расам —
+каждая личная переписка между локальным игроком и другой расой
+оказывается в одной ветке, ключевая по расе собеседника.
+Системные сообщения, административные уведомления и собственные
+рассылки игрока (платный тариф) показываются отдельными
+автономными записями в том же списке и никогда не группируются.
+`read_at` и `deleted_at` поддерживают локальный счётчик
+непрочитанного и кнопку удаления, но не показываются игроку —
+дипломатическая почта не обещает уведомления о прочтении. Форма
+compose выбирает получателя по имени расы (сервер резолвит через
+`Memberships.ListMembers(game_id, "active")`); клиент не тянет
+отдельный список членов. Подробнее — в
+[`ui/docs/diplomail-ui.md`](../ui/docs/diplomail-ui.md).
+
 ### 11.5 Хуки жизненного цикла

 Три транзитных перехода в лобби порождают system mail в inbox
@@ -3070,9 +3070,73 @@ bottom):
 - animated transitions when survivors re-distribute after an
  elimination (currently hard-jumps).

-## Phase 28. Diplomatic Mail View
+## ~~Phase 28. Diplomatic Mail View~~

-Status: pending.
+Status: done (pending CI gate).
+
+Decisions baked in during implementation:
+
+1. **Transport: ConnectRPC `user.games.mail.*`.** Eight new
+   authenticated commands (inbox / sent / message.get / send /
+   broadcast / admin / read / delete) plumbed end-to-end through
+   the existing gateway → backend REST surface. Schemas in
+   `pkg/schema/fbs/diplomail.fbs`; constants in
+   `pkg/model/diplomail/diplomail.go`; gateway translation in
+   `gateway/internal/backendclient/mail_commands.go`.
+2. **Recipient by race name.** The send / admin endpoints accept
+   an alternative `recipient_race_name` field; backend resolves it
+   via `Memberships.ListMembers(gameID, "active")`. The UI feeds
+   the picker straight off `report.races[].name` — no client-side
+   memberships RPC.
+3. **`sender_race_name` snapshot.** New nullable column on
+   `diplomail_messages`, populated for `sender_kind='player'`
+   senders that have an active membership at send time. Drives the
+   per-race threading on the client.
+4. **/sent returns full message detail.** Backend's bulk sent
+   listing now returns the same `UserMailMessageDetail` shape as
+   `/inbox`, one row per (message, recipient). The UI collapses
+   broadcasts by `message_id` into a single stand-alone item.
+5. **Threading + stand-alones.** `MailStore.entries` groups
+   personal messages by the other party's race name. System,
+   admin, and outgoing broadcasts render as stand-alone items in
+   the same list pane.
+6. **No read receipts.** `read_at` and `deleted_at` drive the
+   badge counter and soft-delete affordance but are never shown
+   to the user.
+7. **Header badge.** Inline pill on the view-menu "diplomatic
+   mail" row, fed by `mailStore.unreadCount`. No always-visible
+   chrome added.
+8. **Push event reuse.** A new
+   `eventStream.on("diplomail.message.received", …)` handler in
+   `routes/games/[id]/+layout.svelte` parses the verified payload,
+   refreshes the inbox, and raises a `toast.show` with a "view"
+   deep-link.
+9. **Translation toggle.** Per-message Show original / Show
+   translation toggle inside both `thread-pane.svelte` and
+   `system-item-pane.svelte`; the body defaults to the cached
+   translation when present.
+
+Artifacts (delivered):
+
+- backend: `internal/postgres/migrations/00001_init.sql`,
+  `internal/diplomail/{types.go,store.go,service.go,admin_send.go,diplomail_e2e_test.go,README.md}`,
+  `internal/server/{handlers_user_mail.go,handlers_admin_diplomail.go}`,
+  `openapi.yaml`;
+- wire: `pkg/schema/fbs/diplomail.fbs` + generated Go and TS
+  bindings; `pkg/model/diplomail/diplomail.go`;
+- gateway: `gateway/internal/backendclient/{mail_commands.go,routes.go,mail_commands_test.go}`,
+  `gateway/cmd/gateway/main.go`;
+- ui: `ui/frontend/src/api/diplomail.ts`,
+  `ui/frontend/src/lib/mail-store.svelte.ts`,
+  `ui/frontend/src/lib/active-view/mail.svelte` (+ subdir
+  `mail/{thread-list,thread-pane,system-item-pane,compose,system-titles}.svelte|.ts`),
+  `ui/frontend/src/lib/header/view-menu.svelte`,
+  `ui/frontend/src/routes/games/[id]/+layout.svelte`,
+  `ui/frontend/src/lib/i18n/locales/{en,ru}.ts`;
+- docs: `ui/docs/diplomail-ui.md`, `docs/FUNCTIONAL.md` §11.4 +
+  mirror in `docs/FUNCTIONAL_ru.md`.
+
+Original phase brief follows.

 Goal: implement a mail inbox and compose flow as a dedicated view that
 replaces the map.
@@ -0,0 +1,97 @@
+# In-game diplomatic mail UI
+
+Phase 28 wires the in-game mail view that consumes the `diplomail`
+subsystem in the backend. The route lives at `/games/:id/mail`
+(registered in Phase 10) and replaces the active view when the user
+opens the "diplomatic mail" entry in the header menu.
+
+## Wire surface
+
+Eight ConnectRPC commands sit between UI and backend, all under the
+`user.games.mail.*` namespace:
+
+| Command | Backend REST endpoint |
+|---|---|
+| `user.games.mail.inbox`        | `GET /api/v1/user/games/{id}/mail/inbox` |
+| `user.games.mail.sent`         | `GET …/mail/sent` |
+| `user.games.mail.message.get`  | `GET …/mail/messages/{message_id}` |
+| `user.games.mail.send`         | `POST …/mail/messages` |
+| `user.games.mail.broadcast`    | `POST …/mail/broadcast` |
+| `user.games.mail.admin`        | `POST …/mail/admin` |
+| `user.games.mail.read`         | `POST …/mail/messages/{id}/read` |
+| `user.games.mail.delete`       | `DELETE …/mail/messages/{id}` |
+
+The FlatBuffers schemas live under
+[`pkg/schema/fbs/diplomail.fbs`](../../pkg/schema/fbs/diplomail.fbs);
+the gateway translation lives in
+[`gateway/internal/backendclient/mail_commands.go`](../../gateway/internal/backendclient/mail_commands.go).
+
+## Recipient by race name
+
+The compose flow does **not** consult a memberships listing. The
+recipient picker reads `gameState.report.races[].name` (the Phase 22
+projection of `report.player[]`), and the send request carries the
+chosen race name as `recipient_race_name`. The backend resolves it
+against `Memberships.ListMembers(gameID, "active")` and rejects with
+`forbidden` if the matching member is no longer active. This keeps
+the UI off the lobby surface for the common case.
+
+## Threading model
+
+`MailStore.entries` is the derived rune the active view consumes. It
+projects the union of inbox and sent into:
+
+- **Per-race threads** — every personal message keyed by another
+  race contributes to a thread keyed on that race name. Incoming is
+  keyed on `sender_race_name`; outgoing is keyed on
+  `recipient_race_name`. Thread messages are sorted oldest → newest
+  for chat-style rendering; the unread badge counts incoming
+  `read_at === null` rows only.
+- **Stand-alone items** — system mail (`sender_kind=system`), admin
+  notifications (`sender_kind=admin`), and the caller's own
+  paid-tier broadcasts (`broadcast_scope=game_broadcast`). Backend
+  returns one row per recipient for paid-tier broadcasts; the UI
+  collapses them by `message_id` into a single stand-alone item.
+
+`read_at` and `deleted_at` are not surfaced to the user in any pane
+— they only drive the badge counter and the optimistic mark-read
+state. This is intentional (per Phase 28 decisions): the user-facing
+spec for diplomatic mail does not promise read receipts.
+
+## Translation toggle
+
+When a message detail carries `translated_body`, the body and (if
+non-empty) subject default to the translated rendering. Each message
+pane exposes a "Show original" / "Show translation" button that
+flips the per-message state. Messages without a cached translation
+render the original directly with no toggle.
+
+## Push events
+
+`diplomail.message.received` push frames are dispatched from
+`api/events.svelte.ts` via the singleton SubscribeEvents stream. The
+in-game layout (`routes/games/[id]/+layout.svelte`) parses the
+verified payload, calls `mailStore.applyPushEvent(gameId)` (which
+re-fetches the inbox — the payload only carries a preview), and
+raises a toast through `lib/toast.svelte.ts` with a "view"
+deep-link to `/games/:id/mail`.
+
+The header view-menu's mail entry shows `mailStore.unreadCount` as
+an inline pill — the only chrome the badge needs.
+
+## Layout
+
+Desktop (≥ 768 px) renders a two-pane CSS grid: list on the left,
+detail on the right. Mobile flips to a single-pane stack; tapping a
+list row hides the list and shows the detail with a back button.
+
+## Accessibility
+
+- Bodies render through Svelte's default text-content path (no HTML
+  parsing) per the backend rule of treating message text as plain
+  UTF-8.
+- The compose dialog uses native form controls; the recipient
+  picker is a `<select>` so screen-readers and keyboard users get
+  the standard semantics.
+- The reply box and the compose body are real `<textarea>`s so
+  shift-enter newlines, paste, and selection behave correctly.