Phase 28: mark stage done after CI gate green

Gitea runs at commit 6d0272b:
- go-unit #134 → success
- ui-test #136 → success
- integration #135 → success

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/internal/diplomail/README.md

@@ -26,7 +26,10 @@ Three Postgres tables in the `backend` schema:
 
 - `diplomail_messages` — one row per send (personal, admin, or
   system). Captures `game_name` and IP at insert time so audit
-  rendering survives renames and purges.
+  rendering survives renames and purges. The `sender_race_name`
+  column snapshots the sender's race in the game at send time when
+  the sender is a player with an active membership; the in-game UI
+  keys per-race thread grouping on this column.
 - `diplomail_recipients` — one row per (message, recipient). Holds
   per-user `read_at`, `deleted_at`, `delivered_at`, `notified_at`
   state. Snapshot fields (`recipient_user_name`,
@@ -72,6 +75,24 @@ mail to every active member; `Service.changeMembershipStatus` /
   `detector.LanguageDetector` (default: `whatlanggo`, body-only,
   ≥ 25 runes; shorter bodies stay `und`).
 
+## Recipient selection
+
+`POST /messages` and `POST /admin` (when `target="user"`) accept the
+recipient identifier in one of two shapes:
+
+- `recipient_user_id` (uuid) — explicit user lookup; the recipient
+  may be any active member of the game.
+- `recipient_race_name` (string) — resolves to the active member
+  with this race name in the game. Race names are unique by lobby
+  invariant; lobby-removed and blocked members cannot be reached
+  through the race-name shortcut (they no longer appear in the
+  active scope). Exactly one of the two fields must be supplied;
+  supplying both, or neither, returns `invalid_request`.
+
+The race-name path lets the in-game UI compose mail directly off
+the engine's `report.races[]` view without an extra membership
+round-trip.
+
 ## Translation
 
 Stage D adds a lazy translation cache. When a recipient reads a

backend/internal/diplomail/admin_send.go

@@ -29,7 +29,11 @@ func (s *Service) SendAdminPersonal(ctx context.Context, in SendAdminPersonalInp
 		return Message{}, Recipient{}, err
 	}
 
-	recipient, err := s.deps.Memberships.GetMembershipAnyStatus(ctx, in.GameID, in.RecipientUserID)
+	recipientID, err := s.resolveActiveRecipient(ctx, in.GameID, in.RecipientUserID, in.RecipientRaceName)
+	if err != nil {
+		return Message{}, Recipient{}, err
+	}
+	recipient, err := s.deps.Memberships.GetMembershipAnyStatus(ctx, in.GameID, recipientID)
 	if err != nil {
 		if errors.Is(err, ErrNotFound) {
 			return Message{}, Recipient{}, fmt.Errorf("%w: recipient is not a member of the game", ErrForbidden)
@@ -37,7 +41,7 @@ func (s *Service) SendAdminPersonal(ctx context.Context, in SendAdminPersonalInp
 		return Message{}, Recipient{}, fmt.Errorf("diplomail: load admin recipient: %w", err)
 	}
 
-	msgInsert, err := s.buildAdminMessageInsert(in.CallerKind, in.CallerUserID, in.CallerUsername,
+	msgInsert, err := s.buildAdminMessageInsert(ctx, in.CallerKind, in.CallerUserID, in.CallerUsername,
 		recipient.GameID, recipient.GameName, subject, body, in.SenderIP, BroadcastScopeSingle)
 	if err != nil {
 		return Message{}, Recipient{}, err
@@ -84,7 +88,7 @@ func (s *Service) SendAdminBroadcast(ctx context.Context, in SendAdminBroadcastI
 	}
 
 	gameName := members[0].GameName
-	msgInsert, err := s.buildAdminMessageInsert(in.CallerKind, in.CallerUserID, in.CallerUsername,
+	msgInsert, err := s.buildAdminMessageInsert(ctx, in.CallerKind, in.CallerUserID, in.CallerUsername,
 		in.GameID, gameName, subject, body, in.SenderIP, BroadcastScopeGameBroadcast)
 	if err != nil {
 		return Message{}, nil, err
@@ -147,6 +151,7 @@ func (s *Service) SendPlayerBroadcast(ctx context.Context, in SendPlayerBroadcas
 	}
 
 	username := sender.UserName
+	senderRace := sender.RaceName
 	msgInsert := MessageInsert{
 		MessageID:      uuid.New(),
 		GameID:         in.GameID,
@@ -155,6 +160,7 @@ func (s *Service) SendPlayerBroadcast(ctx context.Context, in SendPlayerBroadcas
 		SenderKind:     SenderKindPlayer,
 		SenderUserID:   &callerID,
 		SenderUsername: &username,
+		SenderRaceName: &senderRace,
 		SenderIP:       in.SenderIP,
 		Subject:        subject,
 		Body:           body,
@@ -217,7 +223,7 @@ func (s *Service) SendAdminMultiGameBroadcast(ctx context.Context, in SendMultiG
 				zap.String("scope", scope))
 			continue
 		}
-		msgInsert, err := s.buildAdminMessageInsert(CallerKindAdmin, nil, in.CallerUsername,
+		msgInsert, err := s.buildAdminMessageInsert(ctx, CallerKindAdmin, nil, in.CallerUsername,
 			game.GameID, game.GameName, subject, body, in.SenderIP, BroadcastScopeMultiGameBroadcast)
 		if err != nil {
 			return nil, 0, err
@@ -356,7 +362,7 @@ func (s *Service) publishGameLifecycle(ctx context.Context, ev LifecycleEvent) e
 	gameName := members[0].GameName
 	subject, body := renderGameLifecycle(ev.Kind, gameName, ev.Actor, ev.Reason)
 
-	msgInsert, err := s.buildAdminMessageInsert(CallerKindSystem, nil, "",
+	msgInsert, err := s.buildAdminMessageInsert(ctx, CallerKindSystem, nil, "",
 		ev.GameID, gameName, subject, body, "", BroadcastScopeGameBroadcast)
 	if err != nil {
 		return err
@@ -385,7 +391,7 @@ func (s *Service) publishMembershipLifecycle(ctx context.Context, ev LifecycleEv
 	}
 	subject, body := renderMembershipLifecycle(ev.Kind, target.GameName, ev.Actor, ev.Reason)
 
-	msgInsert, err := s.buildAdminMessageInsert(CallerKindSystem, nil, "",
+	msgInsert, err := s.buildAdminMessageInsert(ctx, CallerKindSystem, nil, "",
 		ev.GameID, target.GameName, subject, body, "", BroadcastScopeSingle)
 	if err != nil {
 		return err
@@ -417,10 +423,12 @@ func (s *Service) prepareContent(subject, body string) (string, string, error) {
 // for every admin-kind send. The CHECK constraint maps sender
 // shapes:
 //
-//	sender_kind='player'  → CallerKind owner; sender_user_id set
+//	sender_kind='player'  → CallerKind owner; sender_user_id set,
+//	                        sender_race_name resolved from
+//	                        Memberships.GetActiveMembership
 //	sender_kind='admin'   → CallerKind admin; sender_user_id nil
 //	sender_kind='system'  → CallerKind system; sender_username nil
-func (s *Service) buildAdminMessageInsert(callerKind string, callerUserID *uuid.UUID, callerUsername string,
+func (s *Service) buildAdminMessageInsert(ctx context.Context, callerKind string, callerUserID *uuid.UUID, callerUsername string,
 	gameID uuid.UUID, gameName, subject, body, senderIP, scope string) (MessageInsert, error) {
 	out := MessageInsert{
 		MessageID:      uuid.New(),
@@ -443,6 +451,17 @@ func (s *Service) buildAdminMessageInsert(callerKind string, callerUserID *uuid.
 		out.SenderKind = SenderKindPlayer
 		out.SenderUserID = &uid
 		out.SenderUsername = &uname
+		// Owner race snapshot is best-effort: a private-game owner who
+		// has an active membership in their own game contributes a
+		// race name; an owner who is not a current member (or whose
+		// membership is removed/blocked) leaves the field nil. The
+		// CHECK constraint accepts both shapes for sender_kind='player'.
+		if ownerMember, err := s.deps.Memberships.GetActiveMembership(ctx, gameID, uid); err == nil {
+			race := ownerMember.RaceName
+			out.SenderRaceName = &race
+		} else if !errors.Is(err, ErrNotFound) {
+			return MessageInsert{}, fmt.Errorf("diplomail: load owner membership: %w", err)
+		}
 	case CallerKindAdmin:
 		uname := callerUsername
 		out.SenderKind = SenderKindAdmin

backend/internal/diplomail/diplomail_e2e_test.go

@@ -369,6 +369,114 @@ func TestDiplomailPersonalFlow(t *testing.T) {
 	}
 }
 
+// TestDiplomailPersonalByRaceName exercises the Phase 28 contract: the
+// UI passes a recipient race name (read out of the game report); the
+// service resolves it to the active member with that race name and
+// snapshots the sender's race onto the message row. Error cases cover
+// the validation rules baked into the wire schema.
+func TestDiplomailPersonalByRaceName(t *testing.T) {
+	db := startPostgres(t)
+	ctx := context.Background()
+
+	gameID := uuid.New()
+	sender := uuid.New()
+	recipient := uuid.New()
+	kicked := uuid.New()
+	seedAccount(t, db, sender)
+	seedAccount(t, db, recipient)
+	seedAccount(t, db, kicked)
+	seedGame(t, db, gameID, "Race-Name Resolution Game")
+
+	lookup := &staticMembershipLookup{
+		rows: map[[2]uuid.UUID]diplomail.ActiveMembership{
+			{gameID, sender}: {
+				UserID: sender, GameID: gameID, GameName: "Race-Name Resolution Game",
+				UserName: "sender", RaceName: "Senders",
+			},
+			{gameID, recipient}: {
+				UserID: recipient, GameID: gameID, GameName: "Race-Name Resolution Game",
+				UserName: "recipient", RaceName: "Receivers",
+			},
+		},
+		inactive: map[[2]uuid.UUID]diplomail.MemberSnapshot{
+			{gameID, kicked}: {
+				UserID: kicked, GameID: gameID, GameName: "Race-Name Resolution Game",
+				UserName: "kicked", RaceName: "Departed", Status: "removed",
+			},
+		},
+	}
+	svc := diplomail.NewService(diplomail.Deps{
+		Store:        diplomail.NewStore(db),
+		Memberships:  lookup,
+		Notification: &recordingPublisher{},
+		Config: config.DiplomailConfig{
+			MaxBodyBytes:    4096,
+			MaxSubjectBytes: 256,
+		},
+	})
+
+	// Happy path: race name resolves and sender_race_name is snapshotted.
+	msg, rcpt, err := svc.SendPersonal(ctx, diplomail.SendPersonalInput{
+		GameID:            gameID,
+		SenderUserID:      sender,
+		RecipientRaceName: "Receivers",
+		Subject:           "Trade",
+		Body:              "Care to talk?",
+		SenderIP:          "203.0.113.4",
+	})
+	if err != nil {
+		t.Fatalf("send by race name: %v", err)
+	}
+	if rcpt.UserID != recipient {
+		t.Fatalf("recipient = %s, want %s", rcpt.UserID, recipient)
+	}
+	if msg.SenderRaceName == nil || *msg.SenderRaceName != "Senders" {
+		t.Fatalf("sender_race_name = %v, want \"Senders\"", msg.SenderRaceName)
+	}
+
+	// Both identifiers supplied → invalid_request.
+	if _, _, err := svc.SendPersonal(ctx, diplomail.SendPersonalInput{
+		GameID:            gameID,
+		SenderUserID:      sender,
+		RecipientUserID:   recipient,
+		RecipientRaceName: "Receivers",
+		Body:              "x",
+	}); !errors.Is(err, diplomail.ErrInvalidInput) {
+		t.Fatalf("dual identifier: %v, want ErrInvalidInput", err)
+	}
+
+	// Neither identifier supplied → invalid_request.
+	if _, _, err := svc.SendPersonal(ctx, diplomail.SendPersonalInput{
+		GameID:       gameID,
+		SenderUserID: sender,
+		Body:         "x",
+	}); !errors.Is(err, diplomail.ErrInvalidInput) {
+		t.Fatalf("no identifier: %v, want ErrInvalidInput", err)
+	}
+
+	// Race name with no matching active member → invalid_request.
+	if _, _, err := svc.SendPersonal(ctx, diplomail.SendPersonalInput{
+		GameID:            gameID,
+		SenderUserID:      sender,
+		RecipientRaceName: "Strangers",
+		Body:              "x",
+	}); !errors.Is(err, diplomail.ErrInvalidInput) {
+		t.Fatalf("unknown race: %v, want ErrInvalidInput", err)
+	}
+
+	// Race name of a lobby-removed member → invalid_request (the
+	// active-only scope filters them out; the lookup never returns
+	// them).
+	if _, _, err := svc.SendPersonal(ctx, diplomail.SendPersonalInput{
+		GameID:            gameID,
+		SenderUserID:      sender,
+		RecipientRaceName: "Departed",
+		Body:              "x",
+	}); !errors.Is(err, diplomail.ErrInvalidInput) {
+		t.Fatalf("kicked race: %v, want ErrInvalidInput", err)
+	}
+}
+
 func TestDiplomailRejectsNonActiveSender(t *testing.T) {
 	db := startPostgres(t)
 	ctx := context.Background()

backend/internal/diplomail/service.go

@@ -32,15 +32,20 @@ const previewMaxRunes = 120
 // ErrForbidden; the inserted Message is never persisted in those
 // cases.
 func (s *Service) SendPersonal(ctx context.Context, in SendPersonalInput) (Message, Recipient, error) {
-	if in.SenderUserID == in.RecipientUserID {
-		return Message{}, Recipient{}, fmt.Errorf("%w: cannot send mail to yourself", ErrInvalidInput)
-	}
 	subject := strings.TrimRight(in.Subject, " \t")
 	body := strings.TrimRight(in.Body, " \t\n")
 	if err := s.validateContent(subject, body); err != nil {
 		return Message{}, Recipient{}, err
 	}
 
+	recipientID, err := s.resolveActiveRecipient(ctx, in.GameID, in.RecipientUserID, in.RecipientRaceName)
+	if err != nil {
+		return Message{}, Recipient{}, err
+	}
+	if in.SenderUserID == recipientID {
+		return Message{}, Recipient{}, fmt.Errorf("%w: cannot send mail to yourself", ErrInvalidInput)
+	}
+
 	sender, err := s.deps.Memberships.GetActiveMembership(ctx, in.GameID, in.SenderUserID)
 	if err != nil {
 		if errors.Is(err, ErrNotFound) {
@@ -48,7 +53,7 @@ func (s *Service) SendPersonal(ctx context.Context, in SendPersonalInput) (Messa
 		}
 		return Message{}, Recipient{}, fmt.Errorf("diplomail: load sender membership: %w", err)
 	}
-	recipient, err := s.deps.Memberships.GetActiveMembership(ctx, in.GameID, in.RecipientUserID)
+	recipient, err := s.deps.Memberships.GetActiveMembership(ctx, in.GameID, recipientID)
 	if err != nil {
 		if errors.Is(err, ErrNotFound) {
 			return Message{}, Recipient{}, fmt.Errorf("%w: recipient is not an active member of the game", ErrForbidden)
@@ -57,14 +62,17 @@ func (s *Service) SendPersonal(ctx context.Context, in SendPersonalInput) (Messa
 	}
 
 	username := sender.UserName
+	senderRace := sender.RaceName
+	senderUserID := in.SenderUserID
 	msgInsert := MessageInsert{
 		MessageID:      uuid.New(),
 		GameID:         in.GameID,
 		GameName:       sender.GameName,
 		Kind:           KindPersonal,
 		SenderKind:     SenderKindPlayer,
-		SenderUserID:   &in.SenderUserID,
+		SenderUserID:   &senderUserID,
 		SenderUsername: &username,
+		SenderRaceName: &senderRace,
 		SenderIP:       in.SenderIP,
 		Subject:        subject,
 		Body:           body,
@@ -75,7 +83,7 @@ func (s *Service) SendPersonal(ctx context.Context, in SendPersonalInput) (Messa
 	rcptInsert := buildRecipientInsert(
 		msgInsert.MessageID,
 		MemberSnapshot{
-			UserID:            in.RecipientUserID,
+			UserID:            recipientID,
 			GameID:            in.GameID,
 			GameName:          recipient.GameName,
 			UserName:          recipient.UserName,
@@ -101,6 +109,47 @@ func (s *Service) SendPersonal(ctx context.Context, in SendPersonalInput) (Messa
 	return msg, recipients[0], nil
 }
 
+// resolveActiveRecipient turns a (user_id, race_name) pair into the
+// canonical user id of an active member of gameID. Exactly one of the
+// two inputs must be set; both-set or both-empty returns
+// ErrInvalidInput. Race-name resolution is restricted to the active
+// scope so lobby-removed and blocked members cannot be reached
+// through the race-name shortcut. ErrInvalidInput is also returned
+// when the race name matches zero members; ErrForbidden when the
+// race name matches more than one active row (defence in depth — race
+// names are unique within a game by lobby invariant).
+func (s *Service) resolveActiveRecipient(ctx context.Context, gameID uuid.UUID, byUserID uuid.UUID, byRaceName string) (uuid.UUID, error) {
+	byRaceName = strings.TrimSpace(byRaceName)
+	hasUser := byUserID != uuid.Nil
+	hasRace := byRaceName != ""
+	switch {
+	case hasUser && hasRace:
+		return uuid.Nil, fmt.Errorf("%w: only one of recipient_user_id, recipient_race_name may be supplied", ErrInvalidInput)
+	case !hasUser && !hasRace:
+		return uuid.Nil, fmt.Errorf("%w: recipient_user_id or recipient_race_name must be supplied", ErrInvalidInput)
+	case hasUser:
+		return byUserID, nil
+	}
+	members, err := s.deps.Memberships.ListMembers(ctx, gameID, RecipientScopeActive)
+	if err != nil {
+		return uuid.Nil, fmt.Errorf("diplomail: list active members for race lookup: %w", err)
+	}
+	var found []MemberSnapshot
+	for _, m := range members {
+		if m.RaceName == byRaceName {
+			found = append(found, m)
+		}
+	}
+	switch len(found) {
+	case 0:
+		return uuid.Nil, fmt.Errorf("%w: no active member with race %q in this game", ErrInvalidInput, byRaceName)
+	case 1:
+		return found[0].UserID, nil
+	default:
+		return uuid.Nil, fmt.Errorf("%w: race %q matches multiple active members", ErrForbidden, byRaceName)
+	}
+}
+
 // GetMessage returns the InboxEntry for messageID addressed to
 // userID. ErrNotFound is returned when the caller is not a recipient
 // of the message — handlers translate that to 404 so the existence
@@ -267,10 +316,13 @@ func (s *Service) allowedKinds(ctx context.Context, gameID, userID uuid.UUID) (m
 	return map[string]bool{KindAdmin: true}, nil
 }
 
-// ListSent returns personal messages authored by senderUserID in
-// gameID, newest first. Admin/system rows have no `sender_user_id`
-// and are therefore excluded; the user surface does not need them.
-func (s *Service) ListSent(ctx context.Context, gameID, senderUserID uuid.UUID) ([]Message, error) {
+// ListSent returns the sender-side view of personal messages
+// authored by senderUserID in gameID, newest first. Each entry pairs
+// the message with one of its recipient rows; single sends contribute
+// one entry per message, broadcasts contribute one entry per
+// addressee. Admin and system rows have no `sender_user_id` and are
+// therefore excluded; the user surface does not need them.
+func (s *Service) ListSent(ctx context.Context, gameID, senderUserID uuid.UUID) ([]InboxEntry, error) {
 	return s.deps.Store.ListSent(ctx, gameID, senderUserID)
 }
 

backend/internal/diplomail/store.go

@@ -31,7 +31,7 @@ func messageColumns() postgres.ColumnList {
 	m := table.DiplomailMessages
 	return postgres.ColumnList{
 		m.MessageID, m.GameID, m.GameName, m.Kind, m.SenderKind,
-		m.SenderUserID, m.SenderUsername, m.SenderIP,
+		m.SenderUserID, m.SenderUsername, m.SenderRaceName, m.SenderIP,
 		m.Subject, m.Body, m.BodyLang, m.BroadcastScope, m.CreatedAt,
 	}
 }
@@ -59,6 +59,7 @@ type MessageInsert struct {
 	SenderKind     string
 	SenderUserID   *uuid.UUID
 	SenderUsername *string
+	SenderRaceName *string
 	SenderIP       string
 	Subject        string
 	Body           string
@@ -101,7 +102,7 @@ func (s *Store) InsertMessageWithRecipients(ctx context.Context, msg MessageInse
 	m := table.DiplomailMessages
 	msgStmt := m.INSERT(
 		m.MessageID, m.GameID, m.GameName, m.Kind, m.SenderKind,
-		m.SenderUserID, m.SenderUsername, m.SenderIP,
+		m.SenderUserID, m.SenderUsername, m.SenderRaceName, m.SenderIP,
 		m.Subject, m.Body, m.BodyLang, m.BroadcastScope,
 	).VALUES(
 		msg.MessageID,
@@ -111,6 +112,7 @@ func (s *Store) InsertMessageWithRecipients(ctx context.Context, msg MessageInse
 		msg.SenderKind,
 		uuidPtrArg(msg.SenderUserID),
 		stringPtrArg(msg.SenderUsername),
+		stringPtrArg(msg.SenderRaceName),
 		msg.SenderIP,
 		msg.Subject,
 		msg.Body,
@@ -241,25 +243,38 @@ func (s *Store) ListInbox(ctx context.Context, gameID, userID uuid.UUID) ([]Inbo
 	return out, nil
 }
 
-// ListSent returns messages authored by senderUserID in gameID,
-// newest first. Personal messages only — admin/system rows have
-// `sender_user_id IS NULL` and are filtered out by the WHERE clause.
-func (s *Store) ListSent(ctx context.Context, gameID, senderUserID uuid.UUID) ([]Message, error) {
+// ListSent returns the sender-side view of personal messages
+// authored by senderUserID in gameID, newest first. Each
+// `InboxEntry` carries the message together with one of its
+// recipient rows — single sends produce one entry per message;
+// game broadcasts produce one entry per addressee (the in-game
+// mail UI collapses broadcast entries into a single stand-alone
+// item by `message_id`). Admin / system rows have
+// `sender_user_id IS NULL` and are excluded by the WHERE clause.
+func (s *Store) ListSent(ctx context.Context, gameID, senderUserID uuid.UUID) ([]InboxEntry, error) {
 	m := table.DiplomailMessages
-	stmt := postgres.SELECT(messageColumns()).
-		FROM(m).
+	r := table.DiplomailRecipients
+	cols := append(messageColumns(), recipientColumns()...)
+	stmt := postgres.SELECT(cols).
+		FROM(m.INNER_JOIN(r, r.MessageID.EQ(m.MessageID))).
 		WHERE(
 			m.GameID.EQ(postgres.UUID(gameID)).
 				AND(m.SenderUserID.EQ(postgres.UUID(senderUserID))),
 		).
-		ORDER_BY(m.CreatedAt.DESC(), m.MessageID.DESC())
-	var rows []model.DiplomailMessages
-	if err := stmt.QueryContext(ctx, s.db, &rows); err != nil {
+		ORDER_BY(m.CreatedAt.DESC(), m.MessageID.DESC(), r.RecipientID.ASC())
+	var dest []struct {
+		model.DiplomailMessages
+		Recipient model.DiplomailRecipients `alias:"diplomail_recipients"`
+	}
+	if err := stmt.QueryContext(ctx, s.db, &dest); err != nil {
 		return nil, fmt.Errorf("diplomail store: list sent %s/%s: %w", gameID, senderUserID, err)
 	}
-	out := make([]Message, 0, len(rows))
-	for _, row := range rows {
-		out = append(out, messageFromModel(row))
+	out := make([]InboxEntry, 0, len(dest))
+	for _, row := range dest {
+		out = append(out, InboxEntry{
+			Message:   messageFromModel(row.DiplomailMessages),
+			Recipient: recipientFromModel(row.Recipient),
+		})
 	}
 	return out, nil
 }
@@ -737,6 +752,10 @@ func messageFromModel(row model.DiplomailMessages) Message {
 		name := *row.SenderUsername
 		out.SenderUsername = &name
 	}
+	if row.SenderRaceName != nil {
+		name := *row.SenderRaceName
+		out.SenderRaceName = &name
+	}
 	return out
 }
 

backend/internal/diplomail/types.go

@@ -23,6 +23,11 @@ type Message struct {
 	SenderKind     string
 	SenderUserID   *uuid.UUID
 	SenderUsername *string
+	// SenderRaceName carries the snapshot of the sender's race in the
+	// game at send time. Non-nil for sender_kind='player' rows, nil
+	// for admin and system. The in-game mail UI groups personal
+	// threads by this name (Phase 28).
+	SenderRaceName *string
 	SenderIP       string
 	Subject        string
 	Body           string
@@ -92,16 +97,19 @@ type Translation struct {
 }
 
 // SendPersonalInput is the request payload for SendPersonal: the
-// caller sending a single-recipient personal message. Validation
-// (active membership, body length, etc.) is performed inside the
-// service.
+// caller sending a single-recipient personal message. Exactly one of
+// RecipientUserID and RecipientRaceName must be non-zero; the
+// service resolves a non-empty RecipientRaceName to the active
+// member with that race in the game. Other validation (active
+// membership, body length, etc.) is performed inside the service.
 type SendPersonalInput struct {
-	GameID          uuid.UUID
-	SenderUserID    uuid.UUID
-	RecipientUserID uuid.UUID
-	Subject         string
-	Body            string
-	SenderIP        string
+	GameID            uuid.UUID
+	SenderUserID      uuid.UUID
+	RecipientUserID   uuid.UUID
+	RecipientRaceName string
+	Subject           string
+	Body              string
+	SenderIP          string
 }
 
 // CallerKind enumerates the privileged sender roles for admin-kind
@@ -116,17 +124,21 @@ const (
 
 // SendAdminPersonalInput is the request payload for an owner /
 // admin / system sending an admin-kind message to a single
-// recipient. Authorization (owner-vs-admin distinction) is enforced
-// by the HTTP layer; the service trusts the caller designation.
+// recipient. Exactly one of RecipientUserID and RecipientRaceName
+// must be non-zero; the service resolves a non-empty
+// RecipientRaceName to the active member with that race in the
+// game. Authorization (owner-vs-admin distinction) is enforced by
+// the HTTP layer; the service trusts the caller designation.
 type SendAdminPersonalInput struct {
-	GameID          uuid.UUID
-	CallerKind      string
-	CallerUserID    *uuid.UUID
-	CallerUsername  string
-	RecipientUserID uuid.UUID
-	Subject         string
-	Body            string
-	SenderIP        string
+	GameID            uuid.UUID
+	CallerKind        string
+	CallerUserID      *uuid.UUID
+	CallerUsername    string
+	RecipientUserID   uuid.UUID
+	RecipientRaceName string
+	Subject           string
+	Body              string
+	SenderIP          string
 }
 
 // SendAdminBroadcastInput is the request payload for an owner /

backend/internal/postgres/jet/backend/model/diplomail_messages.go

@@ -20,6 +20,7 @@ type DiplomailMessages struct {
 	SenderKind     string
 	SenderUserID   *uuid.UUID
 	SenderUsername *string
+	SenderRaceName *string
 	SenderIP       string
 	Subject        string
 	Body           string

backend/internal/postgres/jet/backend/table/diplomail_messages.go

@@ -24,6 +24,7 @@ type diplomailMessagesTable struct {
 	SenderKind     postgres.ColumnString
 	SenderUserID   postgres.ColumnString
 	SenderUsername postgres.ColumnString
+	SenderRaceName postgres.ColumnString
 	SenderIP       postgres.ColumnString
 	Subject        postgres.ColumnString
 	Body           postgres.ColumnString
@@ -78,14 +79,15 @@ func newDiplomailMessagesTableImpl(schemaName, tableName, alias string) diplomai
 		SenderKindColumn     = postgres.StringColumn("sender_kind")
 		SenderUserIDColumn   = postgres.StringColumn("sender_user_id")
 		SenderUsernameColumn = postgres.StringColumn("sender_username")
+		SenderRaceNameColumn = postgres.StringColumn("sender_race_name")
 		SenderIPColumn       = postgres.StringColumn("sender_ip")
 		SubjectColumn        = postgres.StringColumn("subject")
 		BodyColumn           = postgres.StringColumn("body")
 		BodyLangColumn       = postgres.StringColumn("body_lang")
 		BroadcastScopeColumn = postgres.StringColumn("broadcast_scope")
 		CreatedAtColumn      = postgres.TimestampzColumn("created_at")
-		allColumns           = postgres.ColumnList{MessageIDColumn, GameIDColumn, GameNameColumn, KindColumn, SenderKindColumn, SenderUserIDColumn, SenderUsernameColumn, SenderIPColumn, SubjectColumn, BodyColumn, BodyLangColumn, BroadcastScopeColumn, CreatedAtColumn}
-		mutableColumns       = postgres.ColumnList{GameIDColumn, GameNameColumn, KindColumn, SenderKindColumn, SenderUserIDColumn, SenderUsernameColumn, SenderIPColumn, SubjectColumn, BodyColumn, BodyLangColumn, BroadcastScopeColumn, CreatedAtColumn}
+		allColumns           = postgres.ColumnList{MessageIDColumn, GameIDColumn, GameNameColumn, KindColumn, SenderKindColumn, SenderUserIDColumn, SenderUsernameColumn, SenderRaceNameColumn, SenderIPColumn, SubjectColumn, BodyColumn, BodyLangColumn, BroadcastScopeColumn, CreatedAtColumn}
+		mutableColumns       = postgres.ColumnList{GameIDColumn, GameNameColumn, KindColumn, SenderKindColumn, SenderUserIDColumn, SenderUsernameColumn, SenderRaceNameColumn, SenderIPColumn, SubjectColumn, BodyColumn, BodyLangColumn, BroadcastScopeColumn, CreatedAtColumn}
 		defaultColumns       = postgres.ColumnList{SenderIPColumn, SubjectColumn, BodyLangColumn, BroadcastScopeColumn, CreatedAtColumn}
 	)
 
@@ -100,6 +102,7 @@ func newDiplomailMessagesTableImpl(schemaName, tableName, alias string) diplomai
 		SenderKind:     SenderKindColumn,
 		SenderUserID:   SenderUserIDColumn,
 		SenderUsername: SenderUsernameColumn,
+		SenderRaceName: SenderRaceNameColumn,
 		SenderIP:       SenderIPColumn,
 		Subject:        SubjectColumn,
 		Body:           BodyColumn,

backend/internal/postgres/migrations/00001_init.sql

@@ -683,6 +683,11 @@ CREATE TABLE diplomail_messages (
     sender_kind       text        NOT NULL,
     sender_user_id    uuid,
     sender_username   text,
+    -- sender_race_name is the immutable snapshot of the sender's race
+    -- in this game, captured at insert time when sender_kind='player'.
+    -- Admin and system messages carry NULL. The Phase 28 mail UI keys
+    -- per-race threading on this column.
+    sender_race_name  text,
     sender_ip         text        NOT NULL DEFAULT '',
     subject           text        NOT NULL DEFAULT '',
     body              text        NOT NULL,
@@ -698,6 +703,13 @@ CREATE TABLE diplomail_messages (
         (sender_kind = 'admin'  AND sender_user_id IS NULL     AND sender_username IS NOT NULL) OR
         (sender_kind = 'system' AND sender_user_id IS NULL     AND sender_username IS NULL)
     ),
+    -- sender_race_name is only meaningful for player senders. Admin
+    -- and system rows never carry a race; player rows carry one when
+    -- the sender has an active membership at send time (a non-playing
+    -- private-game owner may legitimately have none).
+    CONSTRAINT diplomail_messages_sender_race_chk CHECK (
+        sender_kind = 'player' OR sender_race_name IS NULL
+    ),
     CONSTRAINT diplomail_messages_kind_sender_chk CHECK (
         (kind = 'personal' AND sender_kind = 'player') OR
         (kind = 'admin'    AND sender_kind IN ('player', 'admin', 'system'))

backend/internal/server/handlers_admin_diplomail.go

@@ -60,19 +60,24 @@ func (h *AdminDiplomailHandlers) Send() gin.HandlerFunc {
 		ctx := c.Request.Context()
 		switch req.Target {
 		case "", "user":
-			recipientID, parseErr := uuid.Parse(req.RecipientUserID)
-			if parseErr != nil {
-				httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
-				return
+			var recipientID uuid.UUID
+			if req.RecipientUserID != "" {
+				parsed, parseErr := uuid.Parse(req.RecipientUserID)
+				if parseErr != nil {
+					httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
+					return
+				}
+				recipientID = parsed
 			}
 			msg, rcpt, sendErr := h.svc.SendAdminPersonal(ctx, diplomail.SendAdminPersonalInput{
-				GameID:          gameID,
-				CallerKind:      diplomail.CallerKindAdmin,
-				CallerUsername:  username,
-				RecipientUserID: recipientID,
-				Subject:         req.Subject,
-				Body:            req.Body,
-				SenderIP:        clientip.ExtractSourceIP(c),
+				GameID:            gameID,
+				CallerKind:        diplomail.CallerKindAdmin,
+				CallerUsername:    username,
+				RecipientUserID:   recipientID,
+				RecipientRaceName: req.RecipientRaceName,
+				Subject:           req.Subject,
+				Body:              req.Body,
+				SenderIP:          clientip.ExtractSourceIP(c),
 			})
 			if sendErr != nil {
 				respondDiplomailError(c, h.logger, "admin mail send personal", ctx, sendErr)

backend/internal/server/handlers_user_mail.go

@@ -87,19 +87,24 @@ func (h *UserMailHandlers) SendPersonal() gin.HandlerFunc {
 			httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "request body must be valid JSON")
 			return
 		}
-		recipientID, err := uuid.Parse(req.RecipientUserID)
-		if err != nil {
-			httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
-			return
+		var recipientID uuid.UUID
+		if req.RecipientUserID != "" {
+			parsed, perr := uuid.Parse(req.RecipientUserID)
+			if perr != nil {
+				httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
+				return
+			}
+			recipientID = parsed
 		}
 		ctx := c.Request.Context()
 		msg, rcpt, err := h.svc.SendPersonal(ctx, diplomail.SendPersonalInput{
-			GameID:          gameID,
-			SenderUserID:    userID,
-			RecipientUserID: recipientID,
-			Subject:         req.Subject,
-			Body:            req.Body,
-			SenderIP:        clientip.ExtractSourceIP(c),
+			GameID:            gameID,
+			SenderUserID:      userID,
+			RecipientUserID:   recipientID,
+			RecipientRaceName: req.RecipientRaceName,
+			Subject:           req.Subject,
+			Body:              req.Body,
+			SenderIP:          clientip.ExtractSourceIP(c),
 		})
 		if err != nil {
 			respondDiplomailError(c, h.logger, "user mail send personal", ctx, err)
@@ -189,9 +194,9 @@ func (h *UserMailHandlers) Sent() gin.HandlerFunc {
 			respondDiplomailError(c, h.logger, "user mail sent", ctx, err)
 			return
 		}
-		out := userMailSentListWire{Items: make([]userMailSentSummaryWire, 0, len(items))}
-		for _, m := range items {
-			out.Items = append(out.Items, mailMessageSummaryToWire(m))
+		out := userMailSentListWire{Items: make([]userMailMessageDetailWire, 0, len(items))}
+		for _, entry := range items {
+			out.Items = append(out.Items, mailMessageDetailToWire(entry, false))
 		}
 		c.JSON(http.StatusOK, out)
 	}
@@ -341,21 +346,26 @@ func (h *UserMailHandlers) SendAdmin() gin.HandlerFunc {
 
 		switch req.Target {
 		case "", "user":
-			recipientID, parseErr := uuid.Parse(req.RecipientUserID)
-			if parseErr != nil {
-				httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
-				return
+			var recipientID uuid.UUID
+			if req.RecipientUserID != "" {
+				parsed, parseErr := uuid.Parse(req.RecipientUserID)
+				if parseErr != nil {
+					httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "recipient_user_id must be a valid UUID")
+					return
+				}
+				recipientID = parsed
 			}
 			callerUserID := userID
 			msg, rcpt, sendErr := h.svc.SendAdminPersonal(ctx, diplomail.SendAdminPersonalInput{
-				GameID:          gameID,
-				CallerKind:      diplomail.CallerKindOwner,
-				CallerUserID:    &callerUserID,
-				CallerUsername:  account.UserName,
-				RecipientUserID: recipientID,
-				Subject:         req.Subject,
-				Body:            req.Body,
-				SenderIP:        clientip.ExtractSourceIP(c),
+				GameID:            gameID,
+				CallerKind:        diplomail.CallerKindOwner,
+				CallerUserID:      &callerUserID,
+				CallerUsername:    account.UserName,
+				RecipientUserID:   recipientID,
+				RecipientRaceName: req.RecipientRaceName,
+				Subject:           req.Subject,
+				Body:              req.Body,
+				SenderIP:          clientip.ExtractSourceIP(c),
 			})
 			if sendErr != nil {
 				respondDiplomailError(c, h.logger, "user mail send admin personal", ctx, sendErr)
@@ -449,10 +459,13 @@ func parseMessageIDParam(c *gin.Context) (uuid.UUID, bool) {
 }
 
 // userMailSendRequestWire mirrors the request body for SendPersonal.
+// Exactly one of `recipient_user_id` and `recipient_race_name` must
+// be supplied; the service rejects ambiguous and empty inputs.
 type userMailSendRequestWire struct {
-	RecipientUserID string `json:"recipient_user_id"`
-	Subject         string `json:"subject,omitempty"`
-	Body            string `json:"body"`
+	RecipientUserID   string `json:"recipient_user_id,omitempty"`
+	RecipientRaceName string `json:"recipient_race_name,omitempty"`
+	Subject           string `json:"subject,omitempty"`
+	Body              string `json:"body"`
 }
 
 // userMailSendBroadcastRequestWire mirrors the request body for the
@@ -464,15 +477,16 @@ type userMailSendBroadcastRequestWire struct {
 }
 
 // userMailSendAdminRequestWire mirrors the request body for the
-// owner-only admin send. `target="user"` requires
-// `recipient_user_id`; `target="all"` accepts the optional
-// `recipients` scope (default `active`).
+// owner-only admin send. `target="user"` requires exactly one of
+// `recipient_user_id` and `recipient_race_name`; `target="all"`
+// accepts the optional `recipients` scope (default `active`).
 type userMailSendAdminRequestWire struct {
-	Target          string `json:"target"`
-	RecipientUserID string `json:"recipient_user_id,omitempty"`
-	Recipients      string `json:"recipients,omitempty"`
-	Subject         string `json:"subject,omitempty"`
-	Body            string `json:"body"`
+	Target            string `json:"target"`
+	RecipientUserID   string `json:"recipient_user_id,omitempty"`
+	RecipientRaceName string `json:"recipient_race_name,omitempty"`
+	Recipients        string `json:"recipients,omitempty"`
+	Subject           string `json:"subject,omitempty"`
+	Body              string `json:"body"`
 }
 
 // userMailBroadcastReceiptWire is the response shape returned after a
@@ -524,6 +538,7 @@ type userMailMessageDetailWire struct {
 	SenderKind        string  `json:"sender_kind"`
 	SenderUserID      *string `json:"sender_user_id,omitempty"`
 	SenderUsername    *string `json:"sender_username,omitempty"`
+	SenderRaceName    *string `json:"sender_race_name,omitempty"`
 	Subject           string  `json:"subject,omitempty"`
 	Body              string  `json:"body"`
 	BodyLang          string  `json:"body_lang"`
@@ -540,27 +555,18 @@ type userMailMessageDetailWire struct {
 	Translator        *string `json:"translator,omitempty"`
 }
 
-// userMailSentSummaryWire mirrors the response shape for the
-// sender-side listing. Recipient state is intentionally omitted (one
-// author may have N recipients per broadcast in later stages).
-type userMailSentSummaryWire struct {
-	MessageID      string `json:"message_id"`
-	GameID         string `json:"game_id"`
-	GameName       string `json:"game_name,omitempty"`
-	Kind           string `json:"kind"`
-	Subject        string `json:"subject,omitempty"`
-	Body           string `json:"body"`
-	BodyLang       string `json:"body_lang"`
-	BroadcastScope string `json:"broadcast_scope"`
-	CreatedAt      string `json:"created_at"`
-}
-
 type userMailInboxListWire struct {
 	Items []userMailMessageDetailWire `json:"items"`
 }
 
+// userMailSentListWire mirrors the response shape for the
+// sender-side listing. Phase 28's in-game UI threads sent messages
+// by the recipient's race name, so the wire carries the full
+// message detail (including the recipient snapshot) — single sends
+// contribute one row per message, broadcasts contribute one row per
+// addressee and the UI collapses them by `message_id`.
 type userMailSentListWire struct {
-	Items []userMailSentSummaryWire `json:"items"`
+	Items []userMailMessageDetailWire `json:"items"`
 }
 
 type userMailUnreadCountWire struct {
@@ -597,6 +603,10 @@ func mailMessageDetailToWire(entry diplomail.InboxEntry, justCreated bool) userM
 		s := *entry.SenderUsername
 		out.SenderUsername = &s
 	}
+	if entry.SenderRaceName != nil {
+		s := *entry.SenderRaceName
+		out.SenderRaceName = &s
+	}
 	if entry.Recipient.RecipientRaceName != nil {
 		s := *entry.Recipient.RecipientRaceName
 		out.RecipientRaceName = &s
@@ -624,20 +634,6 @@ func mailMessageDetailToWire(entry diplomail.InboxEntry, justCreated bool) userM
 	return out
 }
 
-func mailMessageSummaryToWire(m diplomail.Message) userMailSentSummaryWire {
-	return userMailSentSummaryWire{
-		MessageID:      m.MessageID.String(),
-		GameID:         m.GameID.String(),
-		GameName:       m.GameName,
-		Kind:           m.Kind,
-		Subject:        m.Subject,
-		Body:           m.Body,
-		BodyLang:       m.BodyLang,
-		BroadcastScope: m.BroadcastScope,
-		CreatedAt:      m.CreatedAt.UTC().Format(timestampLayout),
-	}
-}
-
 // mailRecipientStateToWire renders the recipient row after a
 // mark-read or soft-delete call. The caller only needs the per-user
 // state, not the full message body again.

backend/openapi.yaml

@@ -4068,11 +4068,22 @@ components:
     UserMailSendRequest:
       type: object
       additionalProperties: false
-      required: [recipient_user_id, body]
+      required: [body]
       properties:
         recipient_user_id:
           type: string
           format: uuid
+          description: |
+            Either `recipient_user_id` or `recipient_race_name` must
+            be supplied; supplying both is rejected as
+            `invalid_request`.
+        recipient_race_name:
+          type: string
+          description: |
+            Resolves to the active member with this race name in the
+            game. Mutually exclusive with `recipient_user_id`. The
+            server returns `forbidden` when the matching member is no
+            longer active (lobby-removed / blocked).
         subject:
           type: string
           description: |
@@ -4093,10 +4104,18 @@ components:
           type: string
           format: uuid
           description: |
-            Required when `target="user"`. Identifies the recipient
-            of the personal admin message; the recipient may be in
-            any membership status (admin notifications can reach
-            kicked players).
+            One of `recipient_user_id` and `recipient_race_name` is
+            required when `target="user"`. Identifies the recipient
+            of the personal admin message by uuid; the recipient may
+            be in any membership status (admin notifications can
+            reach kicked players when addressed by user_id).
+        recipient_race_name:
+          type: string
+          description: |
+            Optional alternative to `recipient_user_id` when
+            `target="user"`. Resolves to the active member with this
+            race name in the game; lobby-removed and blocked members
+            cannot be reached through the race-name shortcut.
         recipients:
           type: string
           enum: [active, active_and_removed, all_members]
@@ -4323,6 +4342,17 @@ components:
         sender_username:
           type: string
           nullable: true
+        sender_race_name:
+          type: string
+          nullable: true
+          description: |
+            Snapshot of the sender's race name in this game at send
+            time. Populated when `sender_kind="player"` and the
+            sender had an active membership at send time; nil for
+            admin and system messages, and for player messages sent
+            by a private-game owner who was not an active member at
+            send time. The in-game UI keys per-race threading on this
+            field.
         subject:
           type: string
         body:
@@ -4370,41 +4400,6 @@ components:
         translator:
           type: string
           description: Identifier of the translation engine that produced the cached row.
-    UserMailSentSummary:
-      type: object
-      additionalProperties: false
-      required:
-        - message_id
-        - game_id
-        - kind
-        - body
-        - body_lang
-        - broadcast_scope
-        - created_at
-      properties:
-        message_id:
-          type: string
-          format: uuid
-        game_id:
-          type: string
-          format: uuid
-        game_name:
-          type: string
-        kind:
-          type: string
-          enum: [personal, admin]
-        subject:
-          type: string
-        body:
-          type: string
-        body_lang:
-          type: string
-        broadcast_scope:
-          type: string
-          enum: [single, game_broadcast, multi_game_broadcast]
-        created_at:
-          type: string
-          format: date-time
     UserMailInboxList:
       type: object
       additionalProperties: false
@@ -4415,6 +4410,13 @@ components:
           items:
             $ref: "#/components/schemas/UserMailMessageDetail"
     UserMailSentList:
+      description: |
+        Sender-side listing of personal messages authored by the
+        caller. Each item carries the same shape as inbox entries
+        (including the recipient snapshot); single sends contribute
+        one row per message, broadcasts contribute one row per
+        addressee so the in-game UI can collapse them by
+        `message_id` into a single stand-alone item.
       type: object
       additionalProperties: false
       required: [items]
@@ -4422,7 +4424,7 @@ components:
         items:
           type: array
           items:
-            $ref: "#/components/schemas/UserMailSentSummary"
+            $ref: "#/components/schemas/UserMailMessageDetail"
     UserMailUnreadCount:
       type: object
       additionalProperties: false

docs/FUNCTIONAL.md

@@ -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

docs/FUNCTIONAL_ru.md

@@ -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

gateway/cmd/gateway/main.go

@@ -186,7 +186,8 @@ func newAuthenticatedGRPCDependencies(ctx context.Context, cfg config.Config, lo
 	userRoutes := backendclient.UserRoutes(backend.REST())
 	lobbyRoutes := backendclient.LobbyRoutes(backend.REST())
 	gameRoutes := backendclient.GameRoutes(backend.REST())
-	allRoutes := make(map[string]downstream.Client, len(userRoutes)+len(lobbyRoutes)+len(gameRoutes))
+	mailRoutes := backendclient.MailRoutes(backend.REST())
+	allRoutes := make(map[string]downstream.Client, len(userRoutes)+len(lobbyRoutes)+len(gameRoutes)+len(mailRoutes))
 	for k, v := range userRoutes {
 		allRoutes[k] = v
 	}
@@ -196,6 +197,9 @@ func newAuthenticatedGRPCDependencies(ctx context.Context, cfg config.Config, lo
 	for k, v := range gameRoutes {
 		allRoutes[k] = v
 	}
+	for k, v := range mailRoutes {
+		allRoutes[k] = v
+	}
 
 	cleanup := func() error {
 		return closeRedisClient()

gateway/internal/backendclient/mail_commands.go

@@ -0,0 +1,567 @@
+package backendclient
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"galaxy/gateway/internal/downstream"
+	diplomailmodel "galaxy/model/diplomail"
+	commonfbs "galaxy/schema/fbs/common"
+	fbs "galaxy/schema/fbs/diplomail"
+
+	flatbuffers "github.com/google/flatbuffers/go"
+	"github.com/google/uuid"
+)
+
+// ExecuteMailCommand routes one authenticated `user.games.mail.*`
+// command into the matching `/api/v1/user/games/{game_id}/mail/...`
+// backend REST endpoint. Each command decodes a FlatBuffers request
+// payload, issues the REST call, decodes the JSON response, and
+// re-encodes the result as a typed FlatBuffers envelope.
+func (c *RESTClient) ExecuteMailCommand(ctx context.Context, command downstream.AuthenticatedCommand) (downstream.UnaryResult, error) {
+	if c == nil || c.httpClient == nil {
+		return downstream.UnaryResult{}, errors.New("backendclient: execute mail command: nil client")
+	}
+	if ctx == nil {
+		return downstream.UnaryResult{}, errors.New("backendclient: execute mail command: nil context")
+	}
+	if err := ctx.Err(); err != nil {
+		return downstream.UnaryResult{}, err
+	}
+	if strings.TrimSpace(command.UserID) == "" {
+		return downstream.UnaryResult{}, errors.New("backendclient: execute mail command: user_id must not be empty")
+	}
+
+	switch command.MessageType {
+	case diplomailmodel.MessageTypeUserGamesMailInbox:
+		return c.executeMailInbox(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailSent:
+		return c.executeMailSent(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailMessageGet:
+		return c.executeMailMessageGet(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailSend:
+		return c.executeMailSend(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailBroadcast:
+		return c.executeMailBroadcast(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailAdmin:
+		return c.executeMailAdmin(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailRead:
+		return c.executeMailRead(ctx, command.UserID, command.PayloadBytes)
+	case diplomailmodel.MessageTypeUserGamesMailDelete:
+		return c.executeMailDelete(ctx, command.UserID, command.PayloadBytes)
+	default:
+		return downstream.UnaryResult{}, fmt.Errorf("backendclient: execute mail command: unsupported message type %q", command.MessageType)
+	}
+}
+
+// mailMessageJSON mirrors the backend's `UserMailMessageDetail` wire
+// shape from `backend/openapi.yaml`. Pointer fields are nullable in
+// the OpenAPI spec; the encoder treats empty strings as "absent".
+type mailMessageJSON struct {
+	MessageID         string  `json:"message_id"`
+	GameID            string  `json:"game_id"`
+	GameName          string  `json:"game_name,omitempty"`
+	Kind              string  `json:"kind"`
+	SenderKind        string  `json:"sender_kind"`
+	SenderUserID      *string `json:"sender_user_id,omitempty"`
+	SenderUsername    *string `json:"sender_username,omitempty"`
+	SenderRaceName    *string `json:"sender_race_name,omitempty"`
+	Subject           string  `json:"subject,omitempty"`
+	Body              string  `json:"body"`
+	BodyLang          string  `json:"body_lang"`
+	BroadcastScope    string  `json:"broadcast_scope"`
+	CreatedAt         string  `json:"created_at"`
+	RecipientUserID   string  `json:"recipient_user_id"`
+	RecipientUserName string  `json:"recipient_user_name,omitempty"`
+	RecipientRaceName *string `json:"recipient_race_name,omitempty"`
+	ReadAt            *string `json:"read_at,omitempty"`
+	DeletedAt         *string `json:"deleted_at,omitempty"`
+	TranslatedSubject *string `json:"translated_subject,omitempty"`
+	TranslatedBody    *string `json:"translated_body,omitempty"`
+	TranslationLang   *string `json:"translation_lang,omitempty"`
+	Translator        *string `json:"translator,omitempty"`
+}
+
+// mailRecipientStateJSON mirrors `UserMailRecipientState`.
+type mailRecipientStateJSON struct {
+	MessageID string  `json:"message_id"`
+	ReadAt    *string `json:"read_at,omitempty"`
+	DeletedAt *string `json:"deleted_at,omitempty"`
+}
+
+// mailBroadcastReceiptJSON mirrors `UserMailBroadcastReceipt`.
+type mailBroadcastReceiptJSON struct {
+	MessageID      string `json:"message_id"`
+	GameID         string `json:"game_id"`
+	GameName       string `json:"game_name,omitempty"`
+	Kind           string `json:"kind"`
+	SenderKind     string `json:"sender_kind"`
+	Subject        string `json:"subject,omitempty"`
+	Body           string `json:"body"`
+	BodyLang       string `json:"body_lang"`
+	BroadcastScope string `json:"broadcast_scope"`
+	CreatedAt      string `json:"created_at"`
+	RecipientCount int    `json:"recipient_count"`
+}
+
+type mailInboxJSON struct {
+	Items []mailMessageJSON `json:"items"`
+}
+
+func (c *RESTClient) executeMailInbox(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.inbox: payload is empty")
+	}
+	flat := fbs.GetRootAsInboxRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	if gameID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.inbox: game_id is missing")
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/inbox"
+	respBody, status, err := c.do(ctx, http.MethodGet, target, userID, nil)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.inbox: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	var resp mailInboxJSON
+	if err := json.Unmarshal(respBody, &resp); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail inbox response: %w", err)
+	}
+	out := encodeMailMessageList(resp.Items, fbs.InboxResponseStart, fbs.InboxResponseAddItems, fbs.InboxResponseEnd, fbs.FinishInboxResponseBuffer)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: out}, nil
+}
+
+func (c *RESTClient) executeMailSent(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.sent: payload is empty")
+	}
+	flat := fbs.GetRootAsSentRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	if gameID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.sent: game_id is missing")
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/sent"
+	respBody, status, err := c.do(ctx, http.MethodGet, target, userID, nil)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.sent: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	var resp mailInboxJSON
+	if err := json.Unmarshal(respBody, &resp); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail sent response: %w", err)
+	}
+	out := encodeMailMessageList(resp.Items, fbs.SentResponseStart, fbs.SentResponseAddItems, fbs.SentResponseEnd, fbs.FinishSentResponseBuffer)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: out}, nil
+}
+
+func (c *RESTClient) executeMailMessageGet(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.message.get: payload is empty")
+	}
+	flat := fbs.GetRootAsMessageGetRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	messageID := readUUID(flat.MessageId(nil))
+	if gameID == uuid.Nil || messageID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.message.get: game_id and message_id are required")
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/messages/" + url.PathEscape(messageID.String())
+	respBody, status, err := c.do(ctx, http.MethodGet, target, userID, nil)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.message.get: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	var msg mailMessageJSON
+	if err := json.Unmarshal(respBody, &msg); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail message response: %w", err)
+	}
+	builder := flatbuffers.NewBuilder(512)
+	msgOff := encodeMailMessage(builder, &msg)
+	fbs.MessageGetResponseStart(builder)
+	fbs.MessageGetResponseAddMessage(builder, msgOff)
+	root := fbs.MessageGetResponseEnd(builder)
+	fbs.FinishMessageGetResponseBuffer(builder, root)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: builder.FinishedBytes()}, nil
+}
+
+func (c *RESTClient) executeMailSend(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.send: payload is empty")
+	}
+	flat := fbs.GetRootAsSendRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	if gameID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.send: game_id is missing")
+	}
+	body := struct {
+		RecipientUserID   string `json:"recipient_user_id,omitempty"`
+		RecipientRaceName string `json:"recipient_race_name,omitempty"`
+		Subject           string `json:"subject,omitempty"`
+		Body              string `json:"body"`
+	}{
+		RecipientUserID:   string(flat.RecipientUserId()),
+		RecipientRaceName: string(flat.RecipientRaceName()),
+		Subject:           string(flat.Subject()),
+		Body:              string(flat.Body()),
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/messages"
+	respBody, status, err := c.do(ctx, http.MethodPost, target, userID, body)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.send: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	var msg mailMessageJSON
+	if err := json.Unmarshal(respBody, &msg); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail send response: %w", err)
+	}
+	builder := flatbuffers.NewBuilder(512)
+	msgOff := encodeMailMessage(builder, &msg)
+	fbs.SendResponseStart(builder)
+	fbs.SendResponseAddMessage(builder, msgOff)
+	root := fbs.SendResponseEnd(builder)
+	fbs.FinishSendResponseBuffer(builder, root)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: builder.FinishedBytes()}, nil
+}
+
+func (c *RESTClient) executeMailBroadcast(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.broadcast: payload is empty")
+	}
+	flat := fbs.GetRootAsBroadcastRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	if gameID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.broadcast: game_id is missing")
+	}
+	body := struct {
+		Subject string `json:"subject,omitempty"`
+		Body    string `json:"body"`
+	}{
+		Subject: string(flat.Subject()),
+		Body:    string(flat.Body()),
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/broadcast"
+	respBody, status, err := c.do(ctx, http.MethodPost, target, userID, body)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.broadcast: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	var receipt mailBroadcastReceiptJSON
+	if err := json.Unmarshal(respBody, &receipt); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail broadcast response: %w", err)
+	}
+	builder := flatbuffers.NewBuilder(256)
+	recOff := encodeMailBroadcastReceipt(builder, &receipt)
+	fbs.BroadcastResponseStart(builder)
+	fbs.BroadcastResponseAddReceipt(builder, recOff)
+	root := fbs.BroadcastResponseEnd(builder)
+	fbs.FinishBroadcastResponseBuffer(builder, root)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: builder.FinishedBytes()}, nil
+}
+
+func (c *RESTClient) executeMailAdmin(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.admin: payload is empty")
+	}
+	flat := fbs.GetRootAsAdminRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	if gameID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.admin: game_id is missing")
+	}
+	target := string(flat.Target())
+	body := struct {
+		Target            string `json:"target"`
+		RecipientUserID   string `json:"recipient_user_id,omitempty"`
+		RecipientRaceName string `json:"recipient_race_name,omitempty"`
+		Recipients        string `json:"recipients,omitempty"`
+		Subject           string `json:"subject,omitempty"`
+		Body              string `json:"body"`
+	}{
+		Target:            target,
+		RecipientUserID:   string(flat.RecipientUserId()),
+		RecipientRaceName: string(flat.RecipientRaceName()),
+		Recipients:        string(flat.Recipients()),
+		Subject:           string(flat.Subject()),
+		Body:              string(flat.Body()),
+	}
+	url := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/admin"
+	respBody, status, err := c.do(ctx, http.MethodPost, url, userID, body)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.admin: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	builder := flatbuffers.NewBuilder(512)
+	if target == "all" {
+		var receipt mailBroadcastReceiptJSON
+		if err := json.Unmarshal(respBody, &receipt); err != nil {
+			return downstream.UnaryResult{}, fmt.Errorf("decode mail admin broadcast response: %w", err)
+		}
+		recOff := encodeMailBroadcastReceipt(builder, &receipt)
+		fbs.AdminResponseStart(builder)
+		fbs.AdminResponseAddReceipt(builder, recOff)
+		root := fbs.AdminResponseEnd(builder)
+		fbs.FinishAdminResponseBuffer(builder, root)
+	} else {
+		var msg mailMessageJSON
+		if err := json.Unmarshal(respBody, &msg); err != nil {
+			return downstream.UnaryResult{}, fmt.Errorf("decode mail admin send response: %w", err)
+		}
+		msgOff := encodeMailMessage(builder, &msg)
+		fbs.AdminResponseStart(builder)
+		fbs.AdminResponseAddMessage(builder, msgOff)
+		root := fbs.AdminResponseEnd(builder)
+		fbs.FinishAdminResponseBuffer(builder, root)
+	}
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: builder.FinishedBytes()}, nil
+}
+
+func (c *RESTClient) executeMailRead(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.read: payload is empty")
+	}
+	flat := fbs.GetRootAsReadRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	messageID := readUUID(flat.MessageId(nil))
+	if gameID == uuid.Nil || messageID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.read: game_id and message_id are required")
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/messages/" + url.PathEscape(messageID.String()) + "/read"
+	respBody, status, err := c.do(ctx, http.MethodPost, target, userID, struct{}{})
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.read: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	return encodeRecipientStateResponse(respBody, fbs.ReadResponseStart, fbs.ReadResponseAddState, fbs.ReadResponseEnd, fbs.FinishReadResponseBuffer)
+}
+
+func (c *RESTClient) executeMailDelete(ctx context.Context, userID string, payload []byte) (downstream.UnaryResult, error) {
+	if len(payload) == 0 {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.delete: payload is empty")
+	}
+	flat := fbs.GetRootAsDeleteRequest(payload, 0)
+	gameID := readUUID(flat.GameId(nil))
+	messageID := readUUID(flat.MessageId(nil))
+	if gameID == uuid.Nil || messageID == uuid.Nil {
+		return downstream.UnaryResult{}, errors.New("execute user.games.mail.delete: game_id and message_id are required")
+	}
+	target := c.baseURL + "/api/v1/user/games/" + url.PathEscape(gameID.String()) + "/mail/messages/" + url.PathEscape(messageID.String())
+	respBody, status, err := c.do(ctx, http.MethodDelete, target, userID, nil)
+	if err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("execute user.games.mail.delete: %w", err)
+	}
+	if status < 200 || status >= 300 {
+		return projectMailErrorResponse(status, respBody)
+	}
+	return encodeRecipientStateResponse(respBody, fbs.DeleteResponseStart, fbs.DeleteResponseAddState, fbs.DeleteResponseEnd, fbs.FinishDeleteResponseBuffer)
+}
+
+// encodeRecipientStateResponse decodes the JSON recipient-state body
+// and emits the corresponding FlatBuffers Read/Delete envelope. The
+// caller supplies the trio of envelope start / add-state / end / finish
+// functions so this helper covers both endpoints with the same shape.
+func encodeRecipientStateResponse(respBody []byte,
+	startFn func(*flatbuffers.Builder),
+	addStateFn func(*flatbuffers.Builder, flatbuffers.UOffsetT),
+	endFn func(*flatbuffers.Builder) flatbuffers.UOffsetT,
+	finishFn func(*flatbuffers.Builder, flatbuffers.UOffsetT),
+) (downstream.UnaryResult, error) {
+	var state mailRecipientStateJSON
+	if err := json.Unmarshal(respBody, &state); err != nil {
+		return downstream.UnaryResult{}, fmt.Errorf("decode mail recipient state: %w", err)
+	}
+	builder := flatbuffers.NewBuilder(128)
+	stateOff := encodeMailRecipientState(builder, &state)
+	startFn(builder)
+	addStateFn(builder, stateOff)
+	root := endFn(builder)
+	finishFn(builder, root)
+	return downstream.UnaryResult{ResultCode: userCommandResultCodeOK, PayloadBytes: builder.FinishedBytes()}, nil
+}
+
+// encodeMailMessageList is a shared helper that encodes a slice of
+// mailMessageJSON items into either an InboxResponse or a
+// SentResponse FlatBuffers envelope. The two envelopes have the same
+// shape (just a `items` vector of MailMessage) so the trio of
+// constructor functions parameterises the helper.
+func encodeMailMessageList(items []mailMessageJSON,
+	startFn func(*flatbuffers.Builder),
+	addItemsFn func(*flatbuffers.Builder, flatbuffers.UOffsetT),
+	endFn func(*flatbuffers.Builder) flatbuffers.UOffsetT,
+	finishFn func(*flatbuffers.Builder, flatbuffers.UOffsetT),
+) []byte {
+	builder := flatbuffers.NewBuilder(1024)
+	offsets := make([]flatbuffers.UOffsetT, 0, len(items))
+	for i := range items {
+		offsets = append(offsets, encodeMailMessage(builder, &items[i]))
+	}
+	// FlatBuffers vectors are built in reverse: prepend each offset.
+	builder.StartVector(4, len(offsets), 4)
+	for i := len(offsets) - 1; i >= 0; i-- {
+		builder.PrependUOffsetT(offsets[i])
+	}
+	itemsVec := builder.EndVector(len(offsets))
+	startFn(builder)
+	addItemsFn(builder, itemsVec)
+	root := endFn(builder)
+	finishFn(builder, root)
+	return builder.FinishedBytes()
+}
+
+// encodeMailMessage builds a MailMessage table inside builder. Returns
+// the offset of the finished table. Strings are interned through the
+// builder; missing JSON fields (nil pointers, empty strings) yield
+// empty FB strings which the readers treat as absent.
+func encodeMailMessage(builder *flatbuffers.Builder, m *mailMessageJSON) flatbuffers.UOffsetT {
+	messageIDOff := builder.CreateString(m.MessageID)
+	gameIDOff := builder.CreateString(m.GameID)
+	gameNameOff := builder.CreateString(m.GameName)
+	kindOff := builder.CreateString(m.Kind)
+	senderKindOff := builder.CreateString(m.SenderKind)
+	senderUserIDOff := builder.CreateString(stringPtrValue(m.SenderUserID))
+	senderUsernameOff := builder.CreateString(stringPtrValue(m.SenderUsername))
+	senderRaceNameOff := builder.CreateString(stringPtrValue(m.SenderRaceName))
+	subjectOff := builder.CreateString(m.Subject)
+	bodyOff := builder.CreateString(m.Body)
+	bodyLangOff := builder.CreateString(m.BodyLang)
+	broadcastScopeOff := builder.CreateString(m.BroadcastScope)
+	recipientUserIDOff := builder.CreateString(m.RecipientUserID)
+	recipientUserNameOff := builder.CreateString(m.RecipientUserName)
+	recipientRaceNameOff := builder.CreateString(stringPtrValue(m.RecipientRaceName))
+	translatedSubjectOff := builder.CreateString(stringPtrValue(m.TranslatedSubject))
+	translatedBodyOff := builder.CreateString(stringPtrValue(m.TranslatedBody))
+	translationLangOff := builder.CreateString(stringPtrValue(m.TranslationLang))
+	translatorOff := builder.CreateString(stringPtrValue(m.Translator))
+
+	fbs.MailMessageStart(builder)
+	fbs.MailMessageAddMessageId(builder, messageIDOff)
+	fbs.MailMessageAddGameId(builder, gameIDOff)
+	fbs.MailMessageAddGameName(builder, gameNameOff)
+	fbs.MailMessageAddKind(builder, kindOff)
+	fbs.MailMessageAddSenderKind(builder, senderKindOff)
+	fbs.MailMessageAddSenderUserId(builder, senderUserIDOff)
+	fbs.MailMessageAddSenderUsername(builder, senderUsernameOff)
+	fbs.MailMessageAddSenderRaceName(builder, senderRaceNameOff)
+	fbs.MailMessageAddSubject(builder, subjectOff)
+	fbs.MailMessageAddBody(builder, bodyOff)
+	fbs.MailMessageAddBodyLang(builder, bodyLangOff)
+	fbs.MailMessageAddBroadcastScope(builder, broadcastScopeOff)
+	fbs.MailMessageAddCreatedAtMs(builder, parseRFC3339Millis(m.CreatedAt))
+	fbs.MailMessageAddRecipientUserId(builder, recipientUserIDOff)
+	fbs.MailMessageAddRecipientUserName(builder, recipientUserNameOff)
+	fbs.MailMessageAddRecipientRaceName(builder, recipientRaceNameOff)
+	fbs.MailMessageAddReadAtMs(builder, parseRFC3339Millis(stringPtrValue(m.ReadAt)))
+	fbs.MailMessageAddDeletedAtMs(builder, parseRFC3339Millis(stringPtrValue(m.DeletedAt)))
+	fbs.MailMessageAddTranslatedSubject(builder, translatedSubjectOff)
+	fbs.MailMessageAddTranslatedBody(builder, translatedBodyOff)
+	fbs.MailMessageAddTranslationLang(builder, translationLangOff)
+	fbs.MailMessageAddTranslator(builder, translatorOff)
+	return fbs.MailMessageEnd(builder)
+}
+
+// encodeMailRecipientState builds a MailRecipientState table.
+func encodeMailRecipientState(builder *flatbuffers.Builder, s *mailRecipientStateJSON) flatbuffers.UOffsetT {
+	messageIDOff := builder.CreateString(s.MessageID)
+	fbs.MailRecipientStateStart(builder)
+	fbs.MailRecipientStateAddMessageId(builder, messageIDOff)
+	fbs.MailRecipientStateAddReadAtMs(builder, parseRFC3339Millis(stringPtrValue(s.ReadAt)))
+	fbs.MailRecipientStateAddDeletedAtMs(builder, parseRFC3339Millis(stringPtrValue(s.DeletedAt)))
+	return fbs.MailRecipientStateEnd(builder)
+}
+
+// encodeMailBroadcastReceipt builds a MailBroadcastReceipt table.
+func encodeMailBroadcastReceipt(builder *flatbuffers.Builder, r *mailBroadcastReceiptJSON) flatbuffers.UOffsetT {
+	messageIDOff := builder.CreateString(r.MessageID)
+	gameIDOff := builder.CreateString(r.GameID)
+	gameNameOff := builder.CreateString(r.GameName)
+	kindOff := builder.CreateString(r.Kind)
+	senderKindOff := builder.CreateString(r.SenderKind)
+	subjectOff := builder.CreateString(r.Subject)
+	bodyOff := builder.CreateString(r.Body)
+	bodyLangOff := builder.CreateString(r.BodyLang)
+	broadcastScopeOff := builder.CreateString(r.BroadcastScope)
+	fbs.MailBroadcastReceiptStart(builder)
+	fbs.MailBroadcastReceiptAddMessageId(builder, messageIDOff)
+	fbs.MailBroadcastReceiptAddGameId(builder, gameIDOff)
+	fbs.MailBroadcastReceiptAddGameName(builder, gameNameOff)
+	fbs.MailBroadcastReceiptAddKind(builder, kindOff)
+	fbs.MailBroadcastReceiptAddSenderKind(builder, senderKindOff)
+	fbs.MailBroadcastReceiptAddSubject(builder, subjectOff)
+	fbs.MailBroadcastReceiptAddBody(builder, bodyOff)
+	fbs.MailBroadcastReceiptAddBodyLang(builder, bodyLangOff)
+	fbs.MailBroadcastReceiptAddBroadcastScope(builder, broadcastScopeOff)
+	fbs.MailBroadcastReceiptAddCreatedAtMs(builder, parseRFC3339Millis(r.CreatedAt))
+	fbs.MailBroadcastReceiptAddRecipientCount(builder, int32(r.RecipientCount))
+	return fbs.MailBroadcastReceiptEnd(builder)
+}
+
+// projectMailErrorResponse maps a non-2xx response into a UnaryResult
+// carrying the backend error envelope, reusing the shared user-mail
+// error-projection. 503 is bubbled as ErrDownstreamUnavailable.
+func projectMailErrorResponse(statusCode int, payload []byte) (downstream.UnaryResult, error) {
+	if statusCode == http.StatusServiceUnavailable {
+		return downstream.UnaryResult{}, downstream.ErrDownstreamUnavailable
+	}
+	if statusCode >= 400 && statusCode <= 599 {
+		return projectUserBackendError(statusCode, payload)
+	}
+	return downstream.UnaryResult{}, fmt.Errorf("unexpected HTTP status %d", statusCode)
+}
+
+// readUUID converts the common.UUID struct (or its absence) into a
+// google/uuid.UUID. Returns uuid.Nil when the input is nil.
+func readUUID(u *commonfbs.UUID) uuid.UUID {
+	if u == nil {
+		return uuid.Nil
+	}
+	var out uuid.UUID
+	hi := u.Hi()
+	lo := u.Lo()
+	for i := 0; i < 8; i++ {
+		out[i] = byte(hi >> (56 - 8*i))
+		out[i+8] = byte(lo >> (56 - 8*i))
+	}
+	return out
+}
+
+// stringPtrValue returns "" for nil and the dereferenced value
+// otherwise. Used to flatten nullable JSON strings into the
+// always-present FlatBuffers string slot.
+func stringPtrValue(p *string) string {
+	if p == nil {
+		return ""
+	}
+	return *p
+}
+
+// parseRFC3339Millis parses an RFC 3339 timestamp string (the format
+// the backend mail handler emits) into Unix milliseconds. Returns 0
+// when the input is empty or unparseable, matching the "absent"
+// convention for the *_at_ms wire fields.
+func parseRFC3339Millis(s string) int64 {
+	if s == "" {
+		return 0
+	}
+	t, err := time.Parse(time.RFC3339Nano, s)
+	if err != nil {
+		return 0
+	}
+	return t.UnixMilli()
+}

gateway/internal/backendclient/mail_commands_test.go

@@ -0,0 +1,209 @@
+package backendclient_test
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"galaxy/gateway/internal/backendclient"
+	diplomailmodel "galaxy/model/diplomail"
+	commonfbs "galaxy/schema/fbs/common"
+	fbs "galaxy/schema/fbs/diplomail"
+
+	flatbuffers "github.com/google/flatbuffers/go"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestExecuteMailInboxDecodesItems(t *testing.T) {
+	t.Parallel()
+
+	gameID := uuid.MustParse("11111111-2222-3333-4444-555555555555")
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, http.MethodGet, r.Method)
+		require.Equal(t, "/api/v1/user/games/"+gameID.String()+"/mail/inbox", r.URL.Path)
+		require.Equal(t, "user-1", r.Header.Get(backendclient.HeaderUserID))
+		writeJSON(t, w, http.StatusOK, map[string]any{
+			"items": []map[string]any{
+				{
+					"message_id":          "00000000-0000-0000-0000-000000000001",
+					"game_id":             gameID.String(),
+					"kind":                "personal",
+					"sender_kind":         "player",
+					"sender_user_id":      "00000000-0000-0000-0000-000000000010",
+					"sender_username":     "alice",
+					"sender_race_name":    "AliceRace",
+					"subject":             "hi",
+					"body":                "hello there",
+					"body_lang":           "en",
+					"broadcast_scope":     "single",
+					"created_at":          "2026-05-15T12:00:00Z",
+					"recipient_user_id":   "00000000-0000-0000-0000-000000000020",
+					"recipient_user_name": "bob",
+					"recipient_race_name": "BobRace",
+				},
+			},
+		})
+	}))
+	t.Cleanup(server.Close)
+
+	client := newRESTClient(t, server)
+	payload := buildInboxRequest(gameID)
+	cmd := newAuthCommand(t, diplomailmodel.MessageTypeUserGamesMailInbox, payload)
+	result, err := client.ExecuteMailCommand(context.Background(), cmd)
+	require.NoError(t, err)
+	assert.Equal(t, "ok", result.ResultCode)
+
+	resp := fbs.GetRootAsInboxResponse(result.PayloadBytes, 0)
+	require.Equal(t, 1, resp.ItemsLength())
+	var item fbs.MailMessage
+	require.True(t, resp.Items(&item, 0))
+	assert.Equal(t, "00000000-0000-0000-0000-000000000001", string(item.MessageId()))
+	assert.Equal(t, "AliceRace", string(item.SenderRaceName()))
+	assert.Equal(t, "BobRace", string(item.RecipientRaceName()))
+}
+
+func TestExecuteMailSendForwardsRaceName(t *testing.T) {
+	t.Parallel()
+
+	gameID := uuid.MustParse("22222222-3333-4444-5555-666666666666")
+	var captured struct {
+		Body              string
+		RecipientUserID   string
+		RecipientRaceName string
+	}
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, http.MethodPost, r.Method)
+		require.Equal(t, "/api/v1/user/games/"+gameID.String()+"/mail/messages", r.URL.Path)
+		var req map[string]any
+		raw, err := io.ReadAll(r.Body)
+		require.NoError(t, err)
+		require.NoError(t, json.Unmarshal(raw, &req))
+		if v, ok := req["body"].(string); ok {
+			captured.Body = v
+		}
+		if v, ok := req["recipient_user_id"].(string); ok {
+			captured.RecipientUserID = v
+		}
+		if v, ok := req["recipient_race_name"].(string); ok {
+			captured.RecipientRaceName = v
+		}
+		writeJSON(t, w, http.StatusCreated, map[string]any{
+			"message_id":          "00000000-0000-0000-0000-000000000099",
+			"game_id":             gameID.String(),
+			"kind":                "personal",
+			"sender_kind":         "player",
+			"sender_user_id":      "00000000-0000-0000-0000-000000000010",
+			"sender_race_name":    "Senders",
+			"body":                captured.Body,
+			"body_lang":           "en",
+			"broadcast_scope":     "single",
+			"created_at":          "2026-05-15T12:00:00Z",
+			"recipient_user_id":   "00000000-0000-0000-0000-000000000020",
+			"recipient_race_name": "Receivers",
+		})
+	}))
+	t.Cleanup(server.Close)
+
+	client := newRESTClient(t, server)
+	payload := buildSendRequestByRaceName(gameID, "Receivers", "let us talk")
+	cmd := newAuthCommand(t, diplomailmodel.MessageTypeUserGamesMailSend, payload)
+	result, err := client.ExecuteMailCommand(context.Background(), cmd)
+	require.NoError(t, err)
+	assert.Equal(t, "ok", result.ResultCode)
+
+	resp := fbs.GetRootAsSendResponse(result.PayloadBytes, 0)
+	require.NotNil(t, resp.Message(nil))
+	msg := resp.Message(nil)
+	assert.Equal(t, "let us talk", string(msg.Body()))
+	assert.Equal(t, "Senders", string(msg.SenderRaceName()))
+	assert.Equal(t, "Receivers", string(msg.RecipientRaceName()))
+
+	assert.Empty(t, captured.RecipientUserID)
+	assert.Equal(t, "Receivers", captured.RecipientRaceName)
+	assert.Equal(t, "let us talk", captured.Body)
+}
+
+func TestExecuteMailReadReturnsState(t *testing.T) {
+	t.Parallel()
+
+	gameID := uuid.MustParse("33333333-4444-5555-6666-777777777777")
+	messageID := uuid.MustParse("00000000-0000-0000-0000-0000000000aa")
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, http.MethodPost, r.Method)
+		require.Equal(t, "/api/v1/user/games/"+gameID.String()+"/mail/messages/"+messageID.String()+"/read", r.URL.Path)
+		writeJSON(t, w, http.StatusOK, map[string]any{
+			"message_id": messageID.String(),
+			"read_at":    "2026-05-15T12:34:56Z",
+		})
+	}))
+	t.Cleanup(server.Close)
+
+	client := newRESTClient(t, server)
+	payload := buildReadRequest(gameID, messageID)
+	cmd := newAuthCommand(t, diplomailmodel.MessageTypeUserGamesMailRead, payload)
+	result, err := client.ExecuteMailCommand(context.Background(), cmd)
+	require.NoError(t, err)
+
+	resp := fbs.GetRootAsReadResponse(result.PayloadBytes, 0)
+	state := resp.State(nil)
+	require.NotNil(t, state)
+	assert.Equal(t, messageID.String(), string(state.MessageId()))
+	assert.NotZero(t, state.ReadAtMs())
+}
+
+// buildInboxRequest emits a FlatBuffers InboxRequest envelope with
+// the supplied game_id.
+func buildInboxRequest(gameID uuid.UUID) []byte {
+	builder := flatbuffers.NewBuilder(64)
+	hi, lo := uuidToHiLo(gameID)
+	fbs.InboxRequestStart(builder)
+	fbs.InboxRequestAddGameId(builder, commonfbs.CreateUUID(builder, hi, lo))
+	root := fbs.InboxRequestEnd(builder)
+	fbs.FinishInboxRequestBuffer(builder, root)
+	return builder.FinishedBytes()
+}
+
+// buildSendRequestByRaceName emits a FlatBuffers SendRequest that
+// addresses the recipient by race name rather than user_id.
+func buildSendRequestByRaceName(gameID uuid.UUID, raceName, body string) []byte {
+	builder := flatbuffers.NewBuilder(128)
+	raceOff := builder.CreateString(raceName)
+	bodyOff := builder.CreateString(body)
+	hi, lo := uuidToHiLo(gameID)
+	fbs.SendRequestStart(builder)
+	fbs.SendRequestAddGameId(builder, commonfbs.CreateUUID(builder, hi, lo))
+	fbs.SendRequestAddRecipientRaceName(builder, raceOff)
+	fbs.SendRequestAddBody(builder, bodyOff)
+	root := fbs.SendRequestEnd(builder)
+	fbs.FinishSendRequestBuffer(builder, root)
+	return builder.FinishedBytes()
+}
+
+// buildReadRequest emits a FlatBuffers ReadRequest envelope.
+func buildReadRequest(gameID, messageID uuid.UUID) []byte {
+	builder := flatbuffers.NewBuilder(64)
+	gameHi, gameLo := uuidToHiLo(gameID)
+	msgHi, msgLo := uuidToHiLo(messageID)
+	fbs.ReadRequestStart(builder)
+	fbs.ReadRequestAddGameId(builder, commonfbs.CreateUUID(builder, gameHi, gameLo))
+	fbs.ReadRequestAddMessageId(builder, commonfbs.CreateUUID(builder, msgHi, msgLo))
+	root := fbs.ReadRequestEnd(builder)
+	fbs.FinishReadRequestBuffer(builder, root)
+	return builder.FinishedBytes()
+}
+
+// uuidToHiLo splits a 16-byte UUID into the two big-endian uint64
+// halves the common.UUID struct uses.
+func uuidToHiLo(u uuid.UUID) (uint64, uint64) {
+	var hi, lo uint64
+	for i := 0; i < 8; i++ {
+		hi = (hi << 8) | uint64(u[i])
+		lo = (lo << 8) | uint64(u[i+8])
+	}
+	return hi, lo
+}

gateway/internal/backendclient/routes.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"galaxy/gateway/internal/downstream"
+	diplomailmodel "galaxy/model/diplomail"
 	lobbymodel "galaxy/model/lobby"
 	ordermodel "galaxy/model/order"
 	reportmodel "galaxy/model/report"
@@ -67,6 +68,27 @@ func GameRoutes(client *RESTClient) map[string]downstream.Client {
 	}
 }
 
+// MailRoutes returns the authenticated `user.games.mail.*` downstream
+// routes served by backend's diplomail subsystem. When client is nil
+// every route resolves to a dependency-unavailable client so the
+// static router still recognises the message types.
+func MailRoutes(client *RESTClient) map[string]downstream.Client {
+	target := downstream.Client(unavailableClient{})
+	if client != nil {
+		target = mailCommandClient{rest: client}
+	}
+	return map[string]downstream.Client{
+		diplomailmodel.MessageTypeUserGamesMailInbox:      target,
+		diplomailmodel.MessageTypeUserGamesMailSent:       target,
+		diplomailmodel.MessageTypeUserGamesMailMessageGet: target,
+		diplomailmodel.MessageTypeUserGamesMailSend:       target,
+		diplomailmodel.MessageTypeUserGamesMailBroadcast:  target,
+		diplomailmodel.MessageTypeUserGamesMailAdmin:      target,
+		diplomailmodel.MessageTypeUserGamesMailRead:       target,
+		diplomailmodel.MessageTypeUserGamesMailDelete:     target,
+	}
+}
+
 type unavailableClient struct{}
 
 func (unavailableClient) ExecuteCommand(context.Context, downstream.AuthenticatedCommand) (downstream.UnaryResult, error) {
@@ -97,9 +119,18 @@ func (c gameCommandClient) ExecuteCommand(ctx context.Context, command downstrea
 	return c.rest.ExecuteGameCommand(ctx, command)
 }
 
+type mailCommandClient struct {
+	rest *RESTClient
+}
+
+func (c mailCommandClient) ExecuteCommand(ctx context.Context, command downstream.AuthenticatedCommand) (downstream.UnaryResult, error) {
+	return c.rest.ExecuteMailCommand(ctx, command)
+}
+
 var (
 	_ downstream.Client = unavailableClient{}
 	_ downstream.Client = userCommandClient{}
 	_ downstream.Client = lobbyCommandClient{}
 	_ downstream.Client = gameCommandClient{}
+	_ downstream.Client = mailCommandClient{}
 )

pkg/model/diplomail/diplomail.go

@@ -0,0 +1,56 @@
+// Package diplomail defines the public typed command identifiers
+// exposed at the authenticated Gateway -> Diplomatic Mail boundary.
+//
+// The gateway routes each `user.games.mail.*` ExecuteCommand into the
+// matching `/api/v1/user/games/{game_id}/mail/*` REST endpoint on the
+// backend; the wire envelopes and payload tables live in
+// `pkg/schema/fbs/diplomail.fbs`.
+package diplomail
+
+const (
+	// MessageTypeUserGamesMailInbox is the authenticated gateway
+	// message type used to read the caller's diplomatic-mail inbox
+	// for one game. Backend filters out rows whose `available_at` is
+	// still nil (translation in flight).
+	MessageTypeUserGamesMailInbox = "user.games.mail.inbox"
+
+	// MessageTypeUserGamesMailSent is the authenticated gateway
+	// message type used to read the caller's outgoing personal
+	// messages for one game. Admin and system rows are not included.
+	MessageTypeUserGamesMailSent = "user.games.mail.sent"
+
+	// MessageTypeUserGamesMailMessageGet is the authenticated
+	// gateway message type used to read a single message detail
+	// addressed to the caller. The response carries the translation
+	// rendering when one is cached for the caller's preferred
+	// language.
+	MessageTypeUserGamesMailMessageGet = "user.games.mail.message.get"
+
+	// MessageTypeUserGamesMailSend is the authenticated gateway
+	// message type used to send a single-recipient personal message.
+	// Exactly one of `recipient_user_id` and `recipient_race_name`
+	// must be supplied; the backend resolves the race-name shortcut
+	// through `Memberships.ListMembers(gameID, "active")`.
+	MessageTypeUserGamesMailSend = "user.games.mail.send"
+
+	// MessageTypeUserGamesMailBroadcast is the authenticated gateway
+	// message type used by paid-tier callers to broadcast a personal
+	// message to every other active member of the game.
+	MessageTypeUserGamesMailBroadcast = "user.games.mail.broadcast"
+
+	// MessageTypeUserGamesMailAdmin is the authenticated gateway
+	// message type used by the game owner to compose an admin-kind
+	// notification. The wire shape is target-discriminated: `user`
+	// addresses a single recipient (by id or race name); `all`
+	// broadcasts to every member matching the requested scope.
+	MessageTypeUserGamesMailAdmin = "user.games.mail.admin"
+
+	// MessageTypeUserGamesMailRead is the authenticated gateway
+	// message type used to mark a single message as read. Idempotent.
+	MessageTypeUserGamesMailRead = "user.games.mail.read"
+
+	// MessageTypeUserGamesMailDelete is the authenticated gateway
+	// message type used to soft-delete a single message. The
+	// recipient row must already be marked read.
+	MessageTypeUserGamesMailDelete = "user.games.mail.delete"
+)

pkg/schema/fbs/diplomail.fbs

@@ -0,0 +1,196 @@
+// diplomail contains FlatBuffers payloads used by the authenticated
+// gateway boundary for the in-game diplomatic-mail subsystem. The
+// wire shapes here mirror the trusted internal
+// `/api/v1/user/games/{game_id}/mail/*` REST surface; gateway derives
+// the calling `user_id` from the verified session and forwards it as
+// `X-User-Id` to backend.
+
+include "common.fbs";
+
+namespace diplomail;
+
+// MailMessage stores one inbox / sent-list / message-detail row. The
+// fields mirror `UserMailMessageDetail` in `backend/openapi.yaml`
+// with the following encoding rules:
+//
+//   - `*_user_id` fields are RFC 4122 string UUIDs ("" means absent
+//     for nullable fields such as `sender_user_id`).
+//   - `*_at_ms` fields carry Unix milliseconds; `0` means the
+//     timestamp is absent (e.g. an unread message has
+//     `read_at_ms == 0`).
+//   - `translated_*`, `translation_lang`, and `translator` are set
+//     when the backend served a cached rendering into the caller's
+//     preferred language; empty otherwise.
+//   - `sender_race_name` is the snapshot of the sender's race name
+//     in this game at send time. Present for `sender_kind="player"`
+//     messages when the sender had an active membership; absent for
+//     admin and system messages. The in-game UI keys per-race
+//     threading on this field.
+table MailMessage {
+  message_id:string;
+  game_id:string;
+  game_name:string;
+  kind:string;
+  sender_kind:string;
+  sender_user_id:string;
+  sender_username:string;
+  sender_race_name:string;
+  subject:string;
+  body:string;
+  body_lang:string;
+  broadcast_scope:string;
+  created_at_ms:int64;
+  recipient_user_id:string;
+  recipient_user_name:string;
+  recipient_race_name:string;
+  read_at_ms:int64;
+  deleted_at_ms:int64;
+  translated_subject:string;
+  translated_body:string;
+  translation_lang:string;
+  translator:string;
+}
+
+// MailRecipientState mirrors the `UserMailRecipientState` payload
+// returned from mark-read and soft-delete endpoints. Same timestamp
+// conventions as `MailMessage`.
+table MailRecipientState {
+  message_id:string;
+  read_at_ms:int64;
+  deleted_at_ms:int64;
+}
+
+// MailBroadcastReceipt mirrors `UserMailBroadcastReceipt`. Returned
+// from broadcast sends (paid-tier and admin); `recipient_count` is
+// the number of recipient rows the server materialised.
+table MailBroadcastReceipt {
+  message_id:string;
+  game_id:string;
+  game_name:string;
+  kind:string;
+  sender_kind:string;
+  subject:string;
+  body:string;
+  body_lang:string;
+  broadcast_scope:string;
+  created_at_ms:int64;
+  recipient_count:int32;
+}
+
+// InboxRequest stores the read-side request for the caller's inbox
+// in `game_id`. Backend filters to messages with `available_at` set
+// (translation completed when the recipient's preferred language
+// differs from the body language).
+table InboxRequest {
+  game_id:common.UUID (required);
+}
+
+// InboxResponse stores the resulting inbox list, newest first.
+// `items` is empty when the caller has no available messages in
+// this game.
+table InboxResponse {
+  items:[MailMessage];
+}
+
+// SentRequest stores the read-side request for the caller's sent
+// personal messages in `game_id`. Admin / system rows are not
+// included.
+table SentRequest {
+  game_id:common.UUID (required);
+}
+
+// SentResponse stores the caller's outgoing personal-message list.
+// Each `MailMessage` carries the original recipient snapshot.
+table SentResponse {
+  items:[MailMessage];
+}
+
+// MessageGetRequest stores the read-side request for a single
+// message detail. The caller must be a recipient of the message.
+table MessageGetRequest {
+  game_id:common.UUID (required);
+  message_id:common.UUID (required);
+}
+
+// MessageGetResponse stores the fully decorated message detail
+// including any cached translation into the caller's preferred
+// language.
+table MessageGetResponse {
+  message:MailMessage;
+}
+
+// SendRequest stores the write-side request for a single-recipient
+// personal send. Exactly one of `recipient_user_id` /
+// `recipient_race_name` must be supplied; the empty string means
+// "use the other field".
+table SendRequest {
+  game_id:common.UUID (required);
+  recipient_user_id:string;
+  recipient_race_name:string;
+  subject:string;
+  body:string;
+}
+
+// SendResponse echoes the freshly inserted message detail.
+table SendResponse {
+  message:MailMessage;
+}
+
+// BroadcastRequest stores the paid-tier player broadcast. The
+// recipient set is always "every other active member of the game".
+table BroadcastRequest {
+  game_id:common.UUID (required);
+  subject:string;
+  body:string;
+}
+
+// BroadcastResponse stores the receipt returned by the server.
+table BroadcastResponse {
+  receipt:MailBroadcastReceipt;
+}
+
+// AdminRequest stores the owner-only admin send. `target="user"`
+// requires exactly one of `recipient_user_id` / `recipient_race_name`;
+// `target="all"` accepts the optional `recipients` scope (default
+// `active`).
+table AdminRequest {
+  game_id:common.UUID (required);
+  target:string;
+  recipient_user_id:string;
+  recipient_race_name:string;
+  recipients:string;
+  subject:string;
+  body:string;
+}
+
+// AdminResponse carries the result of an admin send. When the
+// request had `target="user"`, `message` is set; when `target="all"`,
+// `receipt` is set. Callers branch on which field is present.
+table AdminResponse {
+  message:MailMessage;
+  receipt:MailBroadcastReceipt;
+}
+
+// ReadRequest stores the mark-read intent for a single message. The
+// caller must be a recipient. Idempotent.
+table ReadRequest {
+  game_id:common.UUID (required);
+  message_id:common.UUID (required);
+}
+
+// ReadResponse echoes the recipient state after the operation.
+table ReadResponse {
+  state:MailRecipientState;
+}
+
+// DeleteRequest stores the soft-delete intent for a single message.
+// The message must already be marked read (HTTP 409 otherwise).
+table DeleteRequest {
+  game_id:common.UUID (required);
+  message_id:common.UUID (required);
+}
+
+// DeleteResponse echoes the recipient state after the operation.
+table DeleteResponse {
+  state:MailRecipientState;
+}

pkg/schema/fbs/diplomail/AdminRequest.go

@@ -0,0 +1,133 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type AdminRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsAdminRequest(buf []byte, offset flatbuffers.UOffsetT) *AdminRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &AdminRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishAdminRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsAdminRequest(buf []byte, offset flatbuffers.UOffsetT) *AdminRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &AdminRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedAdminRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *AdminRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *AdminRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *AdminRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) Target() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) RecipientUserId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) RecipientRaceName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(10))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) Recipients() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(12))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) Subject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(14))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *AdminRequest) Body() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(16))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func AdminRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(7)
+}
+func AdminRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func AdminRequestAddTarget(builder *flatbuffers.Builder, target flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(target), 0)
+}
+func AdminRequestAddRecipientUserId(builder *flatbuffers.Builder, recipientUserId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(recipientUserId), 0)
+}
+func AdminRequestAddRecipientRaceName(builder *flatbuffers.Builder, recipientRaceName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(3, flatbuffers.UOffsetT(recipientRaceName), 0)
+}
+func AdminRequestAddRecipients(builder *flatbuffers.Builder, recipients flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(4, flatbuffers.UOffsetT(recipients), 0)
+}
+func AdminRequestAddSubject(builder *flatbuffers.Builder, subject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(5, flatbuffers.UOffsetT(subject), 0)
+}
+func AdminRequestAddBody(builder *flatbuffers.Builder, body flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(6, flatbuffers.UOffsetT(body), 0)
+}
+func AdminRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/AdminResponse.go

@@ -0,0 +1,81 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type AdminResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsAdminResponse(buf []byte, offset flatbuffers.UOffsetT) *AdminResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &AdminResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishAdminResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsAdminResponse(buf []byte, offset flatbuffers.UOffsetT) *AdminResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &AdminResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedAdminResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *AdminResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *AdminResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *AdminResponse) Message(obj *MailMessage) *MailMessage {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailMessage)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *AdminResponse) Receipt(obj *MailBroadcastReceipt) *MailBroadcastReceipt {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailBroadcastReceipt)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func AdminResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(2)
+}
+func AdminResponseAddMessage(builder *flatbuffers.Builder, message flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(message), 0)
+}
+func AdminResponseAddReceipt(builder *flatbuffers.Builder, receipt flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(receipt), 0)
+}
+func AdminResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/BroadcastRequest.go

@@ -0,0 +1,89 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type BroadcastRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsBroadcastRequest(buf []byte, offset flatbuffers.UOffsetT) *BroadcastRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &BroadcastRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishBroadcastRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsBroadcastRequest(buf []byte, offset flatbuffers.UOffsetT) *BroadcastRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &BroadcastRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedBroadcastRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *BroadcastRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *BroadcastRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *BroadcastRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *BroadcastRequest) Subject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *BroadcastRequest) Body() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func BroadcastRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(3)
+}
+func BroadcastRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func BroadcastRequestAddSubject(builder *flatbuffers.Builder, subject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(subject), 0)
+}
+func BroadcastRequestAddBody(builder *flatbuffers.Builder, body flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(body), 0)
+}
+func BroadcastRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/BroadcastResponse.go

@@ -0,0 +1,65 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type BroadcastResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsBroadcastResponse(buf []byte, offset flatbuffers.UOffsetT) *BroadcastResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &BroadcastResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishBroadcastResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsBroadcastResponse(buf []byte, offset flatbuffers.UOffsetT) *BroadcastResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &BroadcastResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedBroadcastResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *BroadcastResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *BroadcastResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *BroadcastResponse) Receipt(obj *MailBroadcastReceipt) *MailBroadcastReceipt {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailBroadcastReceipt)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func BroadcastResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func BroadcastResponseAddReceipt(builder *flatbuffers.Builder, receipt flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(receipt), 0)
+}
+func BroadcastResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/DeleteRequest.go

@@ -0,0 +1,83 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type DeleteRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsDeleteRequest(buf []byte, offset flatbuffers.UOffsetT) *DeleteRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &DeleteRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishDeleteRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsDeleteRequest(buf []byte, offset flatbuffers.UOffsetT) *DeleteRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &DeleteRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedDeleteRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *DeleteRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *DeleteRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *DeleteRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *DeleteRequest) MessageId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func DeleteRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(2)
+}
+func DeleteRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func DeleteRequestAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(1, flatbuffers.UOffsetT(messageId), 0)
+}
+func DeleteRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/DeleteResponse.go

@@ -0,0 +1,65 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type DeleteResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsDeleteResponse(buf []byte, offset flatbuffers.UOffsetT) *DeleteResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &DeleteResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishDeleteResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsDeleteResponse(buf []byte, offset flatbuffers.UOffsetT) *DeleteResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &DeleteResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedDeleteResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *DeleteResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *DeleteResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *DeleteResponse) State(obj *MailRecipientState) *MailRecipientState {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailRecipientState)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func DeleteResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func DeleteResponseAddState(builder *flatbuffers.Builder, state flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(state), 0)
+}
+func DeleteResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/InboxRequest.go

@@ -0,0 +1,67 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type InboxRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsInboxRequest(buf []byte, offset flatbuffers.UOffsetT) *InboxRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &InboxRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishInboxRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsInboxRequest(buf []byte, offset flatbuffers.UOffsetT) *InboxRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &InboxRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedInboxRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *InboxRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *InboxRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *InboxRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func InboxRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func InboxRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func InboxRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/InboxResponse.go

@@ -0,0 +1,75 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type InboxResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsInboxResponse(buf []byte, offset flatbuffers.UOffsetT) *InboxResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &InboxResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishInboxResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsInboxResponse(buf []byte, offset flatbuffers.UOffsetT) *InboxResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &InboxResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedInboxResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *InboxResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *InboxResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *InboxResponse) Items(obj *MailMessage, j int) bool {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Vector(o)
+		x += flatbuffers.UOffsetT(j) * 4
+		x = rcv._tab.Indirect(x)
+		obj.Init(rcv._tab.Bytes, x)
+		return true
+	}
+	return false
+}
+
+func (rcv *InboxResponse) ItemsLength() int {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.VectorLen(o)
+	}
+	return 0
+}
+
+func InboxResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func InboxResponseAddItems(builder *flatbuffers.Builder, items flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(items), 0)
+}
+func InboxResponseStartItemsVector(builder *flatbuffers.Builder, numElems int) flatbuffers.UOffsetT {
+	return builder.StartVector(4, numElems, 4)
+}
+func InboxResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/MailBroadcastReceipt.go

@@ -0,0 +1,178 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type MailBroadcastReceipt struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsMailBroadcastReceipt(buf []byte, offset flatbuffers.UOffsetT) *MailBroadcastReceipt {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &MailBroadcastReceipt{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishMailBroadcastReceiptBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsMailBroadcastReceipt(buf []byte, offset flatbuffers.UOffsetT) *MailBroadcastReceipt {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &MailBroadcastReceipt{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedMailBroadcastReceiptBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *MailBroadcastReceipt) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *MailBroadcastReceipt) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *MailBroadcastReceipt) MessageId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) GameId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) GameName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) Kind() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(10))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) SenderKind() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(12))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) Subject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(14))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) Body() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(16))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) BodyLang() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(18))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) BroadcastScope() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(20))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailBroadcastReceipt) CreatedAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(22))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailBroadcastReceipt) MutateCreatedAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(22, n)
+}
+
+func (rcv *MailBroadcastReceipt) RecipientCount() int32 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(24))
+	if o != 0 {
+		return rcv._tab.GetInt32(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailBroadcastReceipt) MutateRecipientCount(n int32) bool {
+	return rcv._tab.MutateInt32Slot(24, n)
+}
+
+func MailBroadcastReceiptStart(builder *flatbuffers.Builder) {
+	builder.StartObject(11)
+}
+func MailBroadcastReceiptAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(messageId), 0)
+}
+func MailBroadcastReceiptAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(gameId), 0)
+}
+func MailBroadcastReceiptAddGameName(builder *flatbuffers.Builder, gameName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(gameName), 0)
+}
+func MailBroadcastReceiptAddKind(builder *flatbuffers.Builder, kind flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(3, flatbuffers.UOffsetT(kind), 0)
+}
+func MailBroadcastReceiptAddSenderKind(builder *flatbuffers.Builder, senderKind flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(4, flatbuffers.UOffsetT(senderKind), 0)
+}
+func MailBroadcastReceiptAddSubject(builder *flatbuffers.Builder, subject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(5, flatbuffers.UOffsetT(subject), 0)
+}
+func MailBroadcastReceiptAddBody(builder *flatbuffers.Builder, body flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(6, flatbuffers.UOffsetT(body), 0)
+}
+func MailBroadcastReceiptAddBodyLang(builder *flatbuffers.Builder, bodyLang flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(7, flatbuffers.UOffsetT(bodyLang), 0)
+}
+func MailBroadcastReceiptAddBroadcastScope(builder *flatbuffers.Builder, broadcastScope flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(8, flatbuffers.UOffsetT(broadcastScope), 0)
+}
+func MailBroadcastReceiptAddCreatedAtMs(builder *flatbuffers.Builder, createdAtMs int64) {
+	builder.PrependInt64Slot(9, createdAtMs, 0)
+}
+func MailBroadcastReceiptAddRecipientCount(builder *flatbuffers.Builder, recipientCount int32) {
+	builder.PrependInt32Slot(10, recipientCount, 0)
+}
+func MailBroadcastReceiptEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/MailMessage.go

@@ -0,0 +1,303 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type MailMessage struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsMailMessage(buf []byte, offset flatbuffers.UOffsetT) *MailMessage {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &MailMessage{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishMailMessageBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsMailMessage(buf []byte, offset flatbuffers.UOffsetT) *MailMessage {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &MailMessage{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedMailMessageBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *MailMessage) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *MailMessage) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *MailMessage) MessageId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) GameId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) GameName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) Kind() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(10))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) SenderKind() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(12))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) SenderUserId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(14))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) SenderUsername() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(16))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) SenderRaceName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(18))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) Subject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(20))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) Body() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(22))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) BodyLang() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(24))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) BroadcastScope() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(26))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) CreatedAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(28))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailMessage) MutateCreatedAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(28, n)
+}
+
+func (rcv *MailMessage) RecipientUserId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(30))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) RecipientUserName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(32))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) RecipientRaceName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(34))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) ReadAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(36))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailMessage) MutateReadAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(36, n)
+}
+
+func (rcv *MailMessage) DeletedAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(38))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailMessage) MutateDeletedAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(38, n)
+}
+
+func (rcv *MailMessage) TranslatedSubject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(40))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) TranslatedBody() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(42))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) TranslationLang() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(44))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailMessage) Translator() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(46))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func MailMessageStart(builder *flatbuffers.Builder) {
+	builder.StartObject(22)
+}
+func MailMessageAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(messageId), 0)
+}
+func MailMessageAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(gameId), 0)
+}
+func MailMessageAddGameName(builder *flatbuffers.Builder, gameName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(gameName), 0)
+}
+func MailMessageAddKind(builder *flatbuffers.Builder, kind flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(3, flatbuffers.UOffsetT(kind), 0)
+}
+func MailMessageAddSenderKind(builder *flatbuffers.Builder, senderKind flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(4, flatbuffers.UOffsetT(senderKind), 0)
+}
+func MailMessageAddSenderUserId(builder *flatbuffers.Builder, senderUserId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(5, flatbuffers.UOffsetT(senderUserId), 0)
+}
+func MailMessageAddSenderUsername(builder *flatbuffers.Builder, senderUsername flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(6, flatbuffers.UOffsetT(senderUsername), 0)
+}
+func MailMessageAddSenderRaceName(builder *flatbuffers.Builder, senderRaceName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(7, flatbuffers.UOffsetT(senderRaceName), 0)
+}
+func MailMessageAddSubject(builder *flatbuffers.Builder, subject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(8, flatbuffers.UOffsetT(subject), 0)
+}
+func MailMessageAddBody(builder *flatbuffers.Builder, body flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(9, flatbuffers.UOffsetT(body), 0)
+}
+func MailMessageAddBodyLang(builder *flatbuffers.Builder, bodyLang flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(10, flatbuffers.UOffsetT(bodyLang), 0)
+}
+func MailMessageAddBroadcastScope(builder *flatbuffers.Builder, broadcastScope flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(11, flatbuffers.UOffsetT(broadcastScope), 0)
+}
+func MailMessageAddCreatedAtMs(builder *flatbuffers.Builder, createdAtMs int64) {
+	builder.PrependInt64Slot(12, createdAtMs, 0)
+}
+func MailMessageAddRecipientUserId(builder *flatbuffers.Builder, recipientUserId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(13, flatbuffers.UOffsetT(recipientUserId), 0)
+}
+func MailMessageAddRecipientUserName(builder *flatbuffers.Builder, recipientUserName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(14, flatbuffers.UOffsetT(recipientUserName), 0)
+}
+func MailMessageAddRecipientRaceName(builder *flatbuffers.Builder, recipientRaceName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(15, flatbuffers.UOffsetT(recipientRaceName), 0)
+}
+func MailMessageAddReadAtMs(builder *flatbuffers.Builder, readAtMs int64) {
+	builder.PrependInt64Slot(16, readAtMs, 0)
+}
+func MailMessageAddDeletedAtMs(builder *flatbuffers.Builder, deletedAtMs int64) {
+	builder.PrependInt64Slot(17, deletedAtMs, 0)
+}
+func MailMessageAddTranslatedSubject(builder *flatbuffers.Builder, translatedSubject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(18, flatbuffers.UOffsetT(translatedSubject), 0)
+}
+func MailMessageAddTranslatedBody(builder *flatbuffers.Builder, translatedBody flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(19, flatbuffers.UOffsetT(translatedBody), 0)
+}
+func MailMessageAddTranslationLang(builder *flatbuffers.Builder, translationLang flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(20, flatbuffers.UOffsetT(translationLang), 0)
+}
+func MailMessageAddTranslator(builder *flatbuffers.Builder, translator flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(21, flatbuffers.UOffsetT(translator), 0)
+}
+func MailMessageEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/MailRecipientState.go

@@ -0,0 +1,90 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type MailRecipientState struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsMailRecipientState(buf []byte, offset flatbuffers.UOffsetT) *MailRecipientState {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &MailRecipientState{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishMailRecipientStateBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsMailRecipientState(buf []byte, offset flatbuffers.UOffsetT) *MailRecipientState {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &MailRecipientState{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedMailRecipientStateBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *MailRecipientState) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *MailRecipientState) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *MailRecipientState) MessageId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *MailRecipientState) ReadAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailRecipientState) MutateReadAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(6, n)
+}
+
+func (rcv *MailRecipientState) DeletedAtMs() int64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.GetInt64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *MailRecipientState) MutateDeletedAtMs(n int64) bool {
+	return rcv._tab.MutateInt64Slot(8, n)
+}
+
+func MailRecipientStateStart(builder *flatbuffers.Builder) {
+	builder.StartObject(3)
+}
+func MailRecipientStateAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(messageId), 0)
+}
+func MailRecipientStateAddReadAtMs(builder *flatbuffers.Builder, readAtMs int64) {
+	builder.PrependInt64Slot(1, readAtMs, 0)
+}
+func MailRecipientStateAddDeletedAtMs(builder *flatbuffers.Builder, deletedAtMs int64) {
+	builder.PrependInt64Slot(2, deletedAtMs, 0)
+}
+func MailRecipientStateEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/MessageGetRequest.go

@@ -0,0 +1,83 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type MessageGetRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsMessageGetRequest(buf []byte, offset flatbuffers.UOffsetT) *MessageGetRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &MessageGetRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishMessageGetRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsMessageGetRequest(buf []byte, offset flatbuffers.UOffsetT) *MessageGetRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &MessageGetRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedMessageGetRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *MessageGetRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *MessageGetRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *MessageGetRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *MessageGetRequest) MessageId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func MessageGetRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(2)
+}
+func MessageGetRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func MessageGetRequestAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(1, flatbuffers.UOffsetT(messageId), 0)
+}
+func MessageGetRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/MessageGetResponse.go

@@ -0,0 +1,65 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type MessageGetResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsMessageGetResponse(buf []byte, offset flatbuffers.UOffsetT) *MessageGetResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &MessageGetResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishMessageGetResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsMessageGetResponse(buf []byte, offset flatbuffers.UOffsetT) *MessageGetResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &MessageGetResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedMessageGetResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *MessageGetResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *MessageGetResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *MessageGetResponse) Message(obj *MailMessage) *MailMessage {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailMessage)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func MessageGetResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func MessageGetResponseAddMessage(builder *flatbuffers.Builder, message flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(message), 0)
+}
+func MessageGetResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/ReadRequest.go

@@ -0,0 +1,83 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type ReadRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsReadRequest(buf []byte, offset flatbuffers.UOffsetT) *ReadRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &ReadRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishReadRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsReadRequest(buf []byte, offset flatbuffers.UOffsetT) *ReadRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &ReadRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedReadRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *ReadRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *ReadRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *ReadRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *ReadRequest) MessageId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func ReadRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(2)
+}
+func ReadRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func ReadRequestAddMessageId(builder *flatbuffers.Builder, messageId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(1, flatbuffers.UOffsetT(messageId), 0)
+}
+func ReadRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/ReadResponse.go

@@ -0,0 +1,65 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type ReadResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsReadResponse(buf []byte, offset flatbuffers.UOffsetT) *ReadResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &ReadResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishReadResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsReadResponse(buf []byte, offset flatbuffers.UOffsetT) *ReadResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &ReadResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedReadResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *ReadResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *ReadResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *ReadResponse) State(obj *MailRecipientState) *MailRecipientState {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailRecipientState)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func ReadResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func ReadResponseAddState(builder *flatbuffers.Builder, state flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(state), 0)
+}
+func ReadResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/SendRequest.go

@@ -0,0 +1,111 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type SendRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsSendRequest(buf []byte, offset flatbuffers.UOffsetT) *SendRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &SendRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishSendRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsSendRequest(buf []byte, offset flatbuffers.UOffsetT) *SendRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &SendRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedSendRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *SendRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *SendRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *SendRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *SendRequest) RecipientUserId() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *SendRequest) RecipientRaceName() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *SendRequest) Subject() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(10))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *SendRequest) Body() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(12))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func SendRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(5)
+}
+func SendRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func SendRequestAddRecipientUserId(builder *flatbuffers.Builder, recipientUserId flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(recipientUserId), 0)
+}
+func SendRequestAddRecipientRaceName(builder *flatbuffers.Builder, recipientRaceName flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(recipientRaceName), 0)
+}
+func SendRequestAddSubject(builder *flatbuffers.Builder, subject flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(3, flatbuffers.UOffsetT(subject), 0)
+}
+func SendRequestAddBody(builder *flatbuffers.Builder, body flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(4, flatbuffers.UOffsetT(body), 0)
+}
+func SendRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/SendResponse.go

@@ -0,0 +1,65 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type SendResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsSendResponse(buf []byte, offset flatbuffers.UOffsetT) *SendResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &SendResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishSendResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsSendResponse(buf []byte, offset flatbuffers.UOffsetT) *SendResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &SendResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedSendResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *SendResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *SendResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *SendResponse) Message(obj *MailMessage) *MailMessage {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(MailMessage)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func SendResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func SendResponseAddMessage(builder *flatbuffers.Builder, message flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(message), 0)
+}
+func SendResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/SentRequest.go

@@ -0,0 +1,67 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type SentRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsSentRequest(buf []byte, offset flatbuffers.UOffsetT) *SentRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &SentRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishSentRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsSentRequest(buf []byte, offset flatbuffers.UOffsetT) *SentRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &SentRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedSentRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *SentRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *SentRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *SentRequest) GameId(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func SentRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func SentRequestAddGameId(builder *flatbuffers.Builder, gameId flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(gameId), 0)
+}
+func SentRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/diplomail/SentResponse.go

@@ -0,0 +1,75 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package diplomail
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type SentResponse struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsSentResponse(buf []byte, offset flatbuffers.UOffsetT) *SentResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &SentResponse{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishSentResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsSentResponse(buf []byte, offset flatbuffers.UOffsetT) *SentResponse {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &SentResponse{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedSentResponseBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *SentResponse) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *SentResponse) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *SentResponse) Items(obj *MailMessage, j int) bool {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := rcv._tab.Vector(o)
+		x += flatbuffers.UOffsetT(j) * 4
+		x = rcv._tab.Indirect(x)
+		obj.Init(rcv._tab.Bytes, x)
+		return true
+	}
+	return false
+}
+
+func (rcv *SentResponse) ItemsLength() int {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.VectorLen(o)
+	}
+	return 0
+}
+
+func SentResponseStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func SentResponseAddItems(builder *flatbuffers.Builder, items flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(items), 0)
+}
+func SentResponseStartItemsVector(builder *flatbuffers.Builder, numElems int) flatbuffers.UOffsetT {
+	return builder.StartVector(4, numElems, 4)
+}
+func SentResponseEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

ui/Makefile

@@ -6,7 +6,7 @@ WASM_OUT    := frontend/static/core.wasm
 WASM_EXEC   := frontend/static/wasm_exec.js
 TINYGO_ROOT := $(shell tinygo env TINYGOROOT 2>/dev/null)
 FBS_OUT     := frontend/src/proto/galaxy/fbs
-FBS_INPUTS  := ../pkg/schema/fbs/common.fbs ../pkg/schema/fbs/lobby.fbs ../pkg/schema/fbs/user.fbs ../pkg/schema/fbs/report.fbs ../pkg/schema/fbs/order.fbs
+FBS_INPUTS  := ../pkg/schema/fbs/common.fbs ../pkg/schema/fbs/lobby.fbs ../pkg/schema/fbs/user.fbs ../pkg/schema/fbs/report.fbs ../pkg/schema/fbs/order.fbs ../pkg/schema/fbs/diplomail.fbs
 
 help:
 	@echo "ui targets:"

ui/PLAN.md

@@ -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 (CI gate passed on run 136 — go-unit / ui-test / integration all green at commit 6d0272b).
+
+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.

ui/docs/diplomail-ui.md

@@ -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.

ui/frontend/src/api/diplomail.ts

@@ -0,0 +1,421 @@
+// Typed wrappers around `GalaxyClient.executeCommand` for the eight
+// `user.games.mail.*` Phase 28 ConnectRPC commands. Each wrapper
+// builds the matching FlatBuffers request, decodes the FlatBuffers
+// response, and surfaces backend errors through `MailError` so callers
+// branch on canonical codes (`invalid_request`, `forbidden`,
+// `not_found`, `conflict`).
+
+import { Builder, ByteBuffer } from "flatbuffers";
+
+import type { GalaxyClient } from "./galaxy-client";
+import { uuidToHiLo } from "./game-state";
+import {
+	AdminRequest,
+	AdminResponse,
+	BroadcastRequest,
+	BroadcastResponse,
+	DeleteRequest,
+	DeleteResponse,
+	InboxRequest,
+	InboxResponse,
+	MailMessage as FbsMailMessage,
+	MailRecipientState as FbsMailRecipientState,
+	MailBroadcastReceipt as FbsMailBroadcastReceipt,
+	MessageGetRequest,
+	MessageGetResponse,
+	ReadRequest,
+	ReadResponse,
+	SendRequest,
+	SendResponse,
+	SentRequest,
+	SentResponse,
+} from "../proto/galaxy/fbs/diplomail";
+import { UUID } from "../proto/galaxy/fbs/common";
+import { ErrorResponse as FbsErrorResponse } from "../proto/galaxy/fbs/lobby";
+
+/**
+ * MailError represents a non-`ok` response from a mail RPC. Callers
+ * branch on `code` for canonical error handling and use `message` for
+ * inline UI surfacing.
+ */
+export class MailError extends Error {
+	readonly resultCode: string;
+	readonly code: string;
+
+	constructor(resultCode: string, code: string, message: string) {
+		super(message);
+		this.name = "MailError";
+		this.resultCode = resultCode;
+		this.code = code;
+	}
+}
+
+/**
+ * MailMessage is the typed UI view of a `MailMessage` FlatBuffers row.
+ * Nullable wire fields (`sender_user_id`, timestamps, translation
+ * slots) become `null` here; the empty string from FB readers is
+ * normalised to either `""` or `null` based on field semantics.
+ */
+export interface MailMessage {
+	messageId: string;
+	gameId: string;
+	gameName: string;
+	kind: string;
+	senderKind: string;
+	senderUserId: string | null;
+	senderUsername: string | null;
+	senderRaceName: string | null;
+	subject: string;
+	body: string;
+	bodyLang: string;
+	broadcastScope: string;
+	createdAt: Date;
+	recipientUserId: string;
+	recipientUserName: string;
+	recipientRaceName: string | null;
+	readAt: Date | null;
+	deletedAt: Date | null;
+	translatedSubject: string | null;
+	translatedBody: string | null;
+	translationLang: string | null;
+	translator: string | null;
+}
+
+export interface MailRecipientState {
+	messageId: string;
+	readAt: Date | null;
+	deletedAt: Date | null;
+}
+
+export interface MailBroadcastReceipt {
+	messageId: string;
+	gameId: string;
+	gameName: string;
+	kind: string;
+	senderKind: string;
+	subject: string;
+	body: string;
+	bodyLang: string;
+	broadcastScope: string;
+	createdAt: Date;
+	recipientCount: number;
+}
+
+export interface SendPersonalArgs {
+	gameId: string;
+	raceName: string;
+	subject?: string;
+	body: string;
+}
+
+export interface SendBroadcastArgs {
+	gameId: string;
+	subject?: string;
+	body: string;
+}
+
+export type AdminTarget = "user" | "all";
+
+export interface SendAdminArgs {
+	gameId: string;
+	target: AdminTarget;
+	raceName?: string;
+	recipientUserId?: string;
+	recipients?: string;
+	subject?: string;
+	body: string;
+}
+
+const MESSAGE_TYPE_INBOX = "user.games.mail.inbox";
+const MESSAGE_TYPE_SENT = "user.games.mail.sent";
+const MESSAGE_TYPE_GET = "user.games.mail.message.get";
+const MESSAGE_TYPE_SEND = "user.games.mail.send";
+const MESSAGE_TYPE_BROADCAST = "user.games.mail.broadcast";
+const MESSAGE_TYPE_ADMIN = "user.games.mail.admin";
+const MESSAGE_TYPE_READ = "user.games.mail.read";
+const MESSAGE_TYPE_DELETE = "user.games.mail.delete";
+
+const RESULT_CODE_OK = "ok";
+
+export async function fetchInbox(
+	client: GalaxyClient,
+	gameId: string,
+): Promise<MailMessage[]> {
+	const builder = new Builder(64);
+	const [hi, lo] = uuidToHiLo(gameId);
+	InboxRequest.startInboxRequest(builder);
+	InboxRequest.addGameId(builder, UUID.createUUID(builder, hi, lo));
+	builder.finish(InboxRequest.endInboxRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_INBOX, builder.asUint8Array());
+	const response = InboxResponse.getRootAsInboxResponse(new ByteBuffer(payload));
+	return readMessageList(response.itemsLength.bind(response), (i) => response.items(i));
+}
+
+export async function fetchSent(
+	client: GalaxyClient,
+	gameId: string,
+): Promise<MailMessage[]> {
+	const builder = new Builder(64);
+	const [hi, lo] = uuidToHiLo(gameId);
+	SentRequest.startSentRequest(builder);
+	SentRequest.addGameId(builder, UUID.createUUID(builder, hi, lo));
+	builder.finish(SentRequest.endSentRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_SENT, builder.asUint8Array());
+	const response = SentResponse.getRootAsSentResponse(new ByteBuffer(payload));
+	return readMessageList(response.itemsLength.bind(response), (i) => response.items(i));
+}
+
+export async function fetchMessage(
+	client: GalaxyClient,
+	gameId: string,
+	messageId: string,
+): Promise<MailMessage> {
+	const builder = new Builder(64);
+	const [ghi, glo] = uuidToHiLo(gameId);
+	const [mhi, mlo] = uuidToHiLo(messageId);
+	MessageGetRequest.startMessageGetRequest(builder);
+	MessageGetRequest.addGameId(builder, UUID.createUUID(builder, ghi, glo));
+	MessageGetRequest.addMessageId(builder, UUID.createUUID(builder, mhi, mlo));
+	builder.finish(MessageGetRequest.endMessageGetRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_GET, builder.asUint8Array());
+	const response = MessageGetResponse.getRootAsMessageGetResponse(new ByteBuffer(payload));
+	const fb = response.message();
+	if (fb === null) {
+		throw new MailError("internal_error", "internal_error", "message missing in response");
+	}
+	return decodeMailMessage(fb);
+}
+
+export async function sendPersonal(
+	client: GalaxyClient,
+	input: SendPersonalArgs,
+): Promise<MailMessage> {
+	const builder = new Builder(256);
+	const [hi, lo] = uuidToHiLo(input.gameId);
+	const raceOff = builder.createString(input.raceName);
+	const subjectOff = builder.createString(input.subject ?? "");
+	const bodyOff = builder.createString(input.body);
+	SendRequest.startSendRequest(builder);
+	SendRequest.addGameId(builder, UUID.createUUID(builder, hi, lo));
+	SendRequest.addRecipientRaceName(builder, raceOff);
+	SendRequest.addSubject(builder, subjectOff);
+	SendRequest.addBody(builder, bodyOff);
+	builder.finish(SendRequest.endSendRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_SEND, builder.asUint8Array());
+	const response = SendResponse.getRootAsSendResponse(new ByteBuffer(payload));
+	const fb = response.message();
+	if (fb === null) {
+		throw new MailError("internal_error", "internal_error", "message missing in response");
+	}
+	return decodeMailMessage(fb);
+}
+
+export async function sendBroadcast(
+	client: GalaxyClient,
+	input: SendBroadcastArgs,
+): Promise<MailBroadcastReceipt> {
+	const builder = new Builder(256);
+	const [hi, lo] = uuidToHiLo(input.gameId);
+	const subjectOff = builder.createString(input.subject ?? "");
+	const bodyOff = builder.createString(input.body);
+	BroadcastRequest.startBroadcastRequest(builder);
+	BroadcastRequest.addGameId(builder, UUID.createUUID(builder, hi, lo));
+	BroadcastRequest.addSubject(builder, subjectOff);
+	BroadcastRequest.addBody(builder, bodyOff);
+	builder.finish(BroadcastRequest.endBroadcastRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_BROADCAST, builder.asUint8Array());
+	const response = BroadcastResponse.getRootAsBroadcastResponse(new ByteBuffer(payload));
+	const fb = response.receipt();
+	if (fb === null) {
+		throw new MailError("internal_error", "internal_error", "receipt missing in response");
+	}
+	return decodeMailBroadcastReceipt(fb);
+}
+
+export async function sendAdmin(
+	client: GalaxyClient,
+	input: SendAdminArgs,
+): Promise<MailMessage | MailBroadcastReceipt> {
+	const builder = new Builder(256);
+	const [hi, lo] = uuidToHiLo(input.gameId);
+	const targetOff = builder.createString(input.target);
+	const recipientUserOff = builder.createString(input.recipientUserId ?? "");
+	const recipientRaceOff = builder.createString(input.raceName ?? "");
+	const recipientsOff = builder.createString(input.recipients ?? "");
+	const subjectOff = builder.createString(input.subject ?? "");
+	const bodyOff = builder.createString(input.body);
+	AdminRequest.startAdminRequest(builder);
+	AdminRequest.addGameId(builder, UUID.createUUID(builder, hi, lo));
+	AdminRequest.addTarget(builder, targetOff);
+	AdminRequest.addRecipientUserId(builder, recipientUserOff);
+	AdminRequest.addRecipientRaceName(builder, recipientRaceOff);
+	AdminRequest.addRecipients(builder, recipientsOff);
+	AdminRequest.addSubject(builder, subjectOff);
+	AdminRequest.addBody(builder, bodyOff);
+	builder.finish(AdminRequest.endAdminRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_ADMIN, builder.asUint8Array());
+	const response = AdminResponse.getRootAsAdminResponse(new ByteBuffer(payload));
+	const receipt = response.receipt();
+	if (receipt !== null) {
+		return decodeMailBroadcastReceipt(receipt);
+	}
+	const message = response.message();
+	if (message !== null) {
+		return decodeMailMessage(message);
+	}
+	throw new MailError("internal_error", "internal_error", "admin response carried neither message nor receipt");
+}
+
+export async function markRead(
+	client: GalaxyClient,
+	gameId: string,
+	messageId: string,
+): Promise<MailRecipientState> {
+	const builder = new Builder(64);
+	const [ghi, glo] = uuidToHiLo(gameId);
+	const [mhi, mlo] = uuidToHiLo(messageId);
+	ReadRequest.startReadRequest(builder);
+	ReadRequest.addGameId(builder, UUID.createUUID(builder, ghi, glo));
+	ReadRequest.addMessageId(builder, UUID.createUUID(builder, mhi, mlo));
+	builder.finish(ReadRequest.endReadRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_READ, builder.asUint8Array());
+	const response = ReadResponse.getRootAsReadResponse(new ByteBuffer(payload));
+	const fb = response.state();
+	if (fb === null) {
+		throw new MailError("internal_error", "internal_error", "state missing in response");
+	}
+	return decodeMailRecipientState(fb);
+}
+
+export async function deleteMessage(
+	client: GalaxyClient,
+	gameId: string,
+	messageId: string,
+): Promise<MailRecipientState> {
+	const builder = new Builder(64);
+	const [ghi, glo] = uuidToHiLo(gameId);
+	const [mhi, mlo] = uuidToHiLo(messageId);
+	DeleteRequest.startDeleteRequest(builder);
+	DeleteRequest.addGameId(builder, UUID.createUUID(builder, ghi, glo));
+	DeleteRequest.addMessageId(builder, UUID.createUUID(builder, mhi, mlo));
+	builder.finish(DeleteRequest.endDeleteRequest(builder));
+	const payload = await execute(client, MESSAGE_TYPE_DELETE, builder.asUint8Array());
+	const response = DeleteResponse.getRootAsDeleteResponse(new ByteBuffer(payload));
+	const fb = response.state();
+	if (fb === null) {
+		throw new MailError("internal_error", "internal_error", "state missing in response");
+	}
+	return decodeMailRecipientState(fb);
+}
+
+async function execute(
+	client: GalaxyClient,
+	messageType: string,
+	payloadBytes: Uint8Array,
+): Promise<Uint8Array> {
+	const result = await client.executeCommand(messageType, payloadBytes);
+	if (result.resultCode !== RESULT_CODE_OK) {
+		throw decodeMailError(result.resultCode, result.payloadBytes);
+	}
+	return result.payloadBytes;
+}
+
+function decodeMailError(resultCode: string, payload: Uint8Array): MailError {
+	let code = resultCode;
+	let message = resultCode;
+	try {
+		const errorResponse = FbsErrorResponse.getRootAsErrorResponse(new ByteBuffer(payload));
+		const body = errorResponse.error();
+		if (body) {
+			code = body.code() ?? resultCode;
+			message = body.message() ?? resultCode;
+		}
+	} catch (_err) {
+		// fall through to use raw resultCode
+	}
+	return new MailError(resultCode, code, message);
+}
+
+function readMessageList(
+	lengthFn: () => number,
+	getFn: (i: number) => FbsMailMessage | null,
+): MailMessage[] {
+	const total = lengthFn();
+	const out: MailMessage[] = [];
+	for (let i = 0; i < total; i++) {
+		const item = getFn(i);
+		if (item) {
+			out.push(decodeMailMessage(item));
+		}
+	}
+	return out;
+}
+
+function decodeMailMessage(fb: FbsMailMessage): MailMessage {
+	return {
+		messageId: fb.messageId() ?? "",
+		gameId: fb.gameId() ?? "",
+		gameName: fb.gameName() ?? "",
+		kind: fb.kind() ?? "",
+		senderKind: fb.senderKind() ?? "",
+		senderUserId: optionalString(fb.senderUserId()),
+		senderUsername: optionalString(fb.senderUsername()),
+		senderRaceName: optionalString(fb.senderRaceName()),
+		subject: fb.subject() ?? "",
+		body: fb.body() ?? "",
+		bodyLang: fb.bodyLang() ?? "",
+		broadcastScope: fb.broadcastScope() ?? "",
+		createdAt: dateFromMs(fb.createdAtMs()),
+		recipientUserId: fb.recipientUserId() ?? "",
+		recipientUserName: fb.recipientUserName() ?? "",
+		recipientRaceName: optionalString(fb.recipientRaceName()),
+		readAt: optionalDateFromMs(fb.readAtMs()),
+		deletedAt: optionalDateFromMs(fb.deletedAtMs()),
+		translatedSubject: optionalString(fb.translatedSubject()),
+		translatedBody: optionalString(fb.translatedBody()),
+		translationLang: optionalString(fb.translationLang()),
+		translator: optionalString(fb.translator()),
+	};
+}
+
+function decodeMailRecipientState(fb: FbsMailRecipientState): MailRecipientState {
+	return {
+		messageId: fb.messageId() ?? "",
+		readAt: optionalDateFromMs(fb.readAtMs()),
+		deletedAt: optionalDateFromMs(fb.deletedAtMs()),
+	};
+}
+
+function decodeMailBroadcastReceipt(fb: FbsMailBroadcastReceipt): MailBroadcastReceipt {
+	return {
+		messageId: fb.messageId() ?? "",
+		gameId: fb.gameId() ?? "",
+		gameName: fb.gameName() ?? "",
+		kind: fb.kind() ?? "",
+		senderKind: fb.senderKind() ?? "",
+		subject: fb.subject() ?? "",
+		body: fb.body() ?? "",
+		bodyLang: fb.bodyLang() ?? "",
+		broadcastScope: fb.broadcastScope() ?? "",
+		createdAt: dateFromMs(fb.createdAtMs()),
+		recipientCount: fb.recipientCount(),
+	};
+}
+
+function optionalString(value: string | null | undefined): string | null {
+	if (value === null || value === undefined || value === "") {
+		return null;
+	}
+	return value;
+}
+
+function dateFromMs(ms: bigint): Date {
+	return new Date(Number(ms));
+}
+
+function optionalDateFromMs(ms: bigint): Date | null {
+	if (ms === 0n) {
+		return null;
+	}
+	return new Date(Number(ms));
+}

ui/frontend/src/lib/active-view/mail.svelte

@@ -1,27 +1,207 @@
 <!--
-Phase 10 stub for the diplomatic-mail active view. Phase 28 wires the
-real mail listing.
+Phase 28 active-view for the diplomatic mail. Replaces the Phase 10
+stub. Renders a two-pane list/detail layout on desktop and a
+one-pane stack on mobile; the inner pieces (thread list, thread
+pane, system-item pane, compose form) live under
+`./mail/*.svelte`.
 -->
 <script lang="ts">
+	import { page } from "$app/state";
+
 	import { i18n } from "$lib/i18n/index.svelte";
+	import { mailStore, type MailListEntry } from "$lib/mail-store.svelte";
+
+	import ThreadList from "./mail/thread-list.svelte";
+	import ThreadPane from "./mail/thread-pane.svelte";
+	import SystemItemPane from "./mail/system-item-pane.svelte";
+	import Compose from "./mail/compose.svelte";
+
+	let selectedKey = $state<string | null>(null);
+	let composeOpen = $state(false);
+
+	const gameId = $derived(page.params.id ?? "");
+
+	const entries = $derived(mailStore.entries);
+
+	const selected = $derived.by<MailListEntry | null>(() => {
+		if (selectedKey === null) {
+			return null;
+		}
+		return entries.find((entry) => entryKey(entry) === selectedKey) ?? null;
+	});
+
+	function entryKey(entry: MailListEntry): string {
+		return entry.kind === "thread"
+			? `thread:${entry.raceName}`
+			: `standalone:${entry.message.messageId}`;
+	}
+
+	function openEntry(entry: MailListEntry): void {
+		selectedKey = entryKey(entry);
+	}
+
+	function closePane(): void {
+		selectedKey = null;
+	}
 </script>
 
-<section class="active-view" data-testid="active-view-mail">
-	<h2>{i18n.t("game.view.mail")}</h2>
-	<p>{i18n.t("game.shell.coming_soon")}</p>
+<section class="mail" data-testid="active-view-mail">
+	<header class="mail-header">
+		<h2>{i18n.t("game.view.mail")}</h2>
+		<button
+			type="button"
+			class="compose-btn"
+			data-testid="mail-compose-open"
+			onclick={() => (composeOpen = true)}
+			disabled={mailStore.status !== "ready"}
+		>
+			{i18n.t("game.mail.compose_action")}
+		</button>
+	</header>
+
+	{#if mailStore.status === "loading"}
+		<p class="status" data-testid="mail-loading">
+			{i18n.t("game.mail.loading")}
+		</p>
+	{:else if mailStore.status === "error"}
+		<p class="status error" data-testid="mail-error">
+			{mailStore.error ?? i18n.t("game.mail.load_failed")}
+		</p>
+	{:else if entries.length === 0}
+		<p class="status" data-testid="mail-empty">
+			{i18n.t("game.mail.empty")}
+		</p>
+	{:else}
+		<div class="panes" class:detail-open={selected !== null}>
+			<div class="list-pane">
+				<ThreadList
+					{entries}
+					selectedKey={selectedKey}
+					onSelect={openEntry}
+				/>
+			</div>
+			<div class="detail-pane">
+				<button
+					type="button"
+					class="back-btn"
+					data-testid="mail-back"
+					onclick={closePane}
+				>
+					{i18n.t("game.mail.back")}
+				</button>
+				{#if selected === null}
+					<p class="status empty-detail">
+						{i18n.t("game.mail.select_thread")}
+					</p>
+				{:else if selected.kind === "thread"}
+					<ThreadPane thread={selected} {gameId} />
+				{:else}
+					<SystemItemPane entry={selected} />
+				{/if}
+			</div>
+		</div>
+	{/if}
+
+	{#if composeOpen}
+		<Compose
+			onClose={() => (composeOpen = false)}
+			onSent={(raceName: string | null) => {
+				composeOpen = false;
+				if (raceName !== null) {
+					selectedKey = `thread:${raceName}`;
+				}
+			}}
+		/>
+	{/if}
 </section>
 
 <style>
-	.active-view {
-		padding: 1.5rem;
+	.mail {
+		display: flex;
+		flex-direction: column;
+		gap: 0.75rem;
+		padding: 1rem;
 		font-family: system-ui, sans-serif;
 	}
-	.active-view h2 {
-		margin: 0 0 0.5rem;
+	.mail-header {
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+	}
+	.mail-header h2 {
+		margin: 0;
 		font-size: 1.1rem;
 	}
-	.active-view p {
-		margin: 0;
-		color: #555;
+	.compose-btn {
+		font: inherit;
+		padding: 0.35rem 0.75rem;
+		border: 1px solid #444;
+		background: #1a1a1a;
+		color: #fff;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.compose-btn:disabled {
+		opacity: 0.5;
+		cursor: not-allowed;
+	}
+	.status {
+		color: #888;
+	}
+	.status.error {
+		color: #c62828;
+	}
+	.panes {
+		display: grid;
+		grid-template-columns: minmax(220px, 280px) 1fr;
+		gap: 1rem;
+		min-height: 320px;
+	}
+	.list-pane,
+	.detail-pane {
+		border: 1px solid #2a2a2a;
+		border-radius: 6px;
+		padding: 0.75rem;
+		background: #111;
+		overflow: hidden;
+	}
+	.list-pane {
+		max-height: 70vh;
+		overflow-y: auto;
+	}
+	.back-btn {
+		display: none;
+		font: inherit;
+		margin-bottom: 0.5rem;
+		padding: 0.25rem 0.5rem;
+		border: 1px solid #444;
+		background: transparent;
+		color: #fff;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.empty-detail {
+		text-align: center;
+		padding: 2rem 0;
+	}
+	@media (max-width: 767px) {
+		.panes {
+			grid-template-columns: 1fr;
+		}
+		.list-pane {
+			display: block;
+		}
+		.detail-pane {
+			display: none;
+		}
+		.panes.detail-open .list-pane {
+			display: none;
+		}
+		.panes.detail-open .detail-pane {
+			display: block;
+		}
+		.panes.detail-open .back-btn {
+			display: inline-block;
+		}
 	}
 </style>

ui/frontend/src/lib/active-view/mail/compose.svelte

@@ -0,0 +1,273 @@
+<!--
+Phase 28 — compose dialog for diplomatic mail. The recipient picker
+reads `gameState.report.races[]` (Phase 22), the kind toggle exposes
+personal / broadcast / admin; broadcast and admin sends are gated
+server-side, the UI surfaces the resulting 403 inline.
+-->
+<script lang="ts">
+	import { getContext } from "svelte";
+
+	import { i18n } from "$lib/i18n/index.svelte";
+	import { mailStore } from "$lib/mail-store.svelte";
+	import {
+		RENDERED_REPORT_CONTEXT_KEY,
+		type RenderedReportSource,
+	} from "$lib/rendered-report.svelte";
+
+	type ComposeKind = "personal" | "broadcast" | "admin";
+	type AdminAudience = "active" | "active_and_removed" | "all_members";
+
+	let {
+		onClose,
+		onSent,
+	}: {
+		onClose: () => void;
+		onSent: (raceName: string | null) => void;
+	} = $props();
+
+	const rendered = getContext<RenderedReportSource | undefined>(
+		RENDERED_REPORT_CONTEXT_KEY,
+	);
+
+	const races = $derived.by<string[]>(() => {
+		const r = rendered?.report;
+		if (!r) {
+			return [];
+		}
+		return r.races.map((race) => race.name);
+	});
+
+	let kind = $state<ComposeKind>("personal");
+	let raceName = $state("");
+	let adminTarget = $state<"user" | "all">("user");
+	let adminAudience = $state<AdminAudience>("active");
+	let subject = $state("");
+	let body = $state("");
+	let error = $state<string | null>(null);
+	let sending = $state(false);
+
+	$effect(() => {
+		if (raceName === "" && races.length > 0) {
+			raceName = races[0];
+		}
+	});
+
+	async function submit(event: SubmitEvent): Promise<void> {
+		event.preventDefault();
+		error = null;
+		const bodyText = body.trim();
+		if (bodyText === "") {
+			error = i18n.t("game.mail.body_required");
+			return;
+		}
+		const needsRecipient = kind === "personal" || (kind === "admin" && adminTarget === "user");
+		if (needsRecipient && raceName === "") {
+			error = i18n.t("game.mail.recipient_required");
+			return;
+		}
+		sending = true;
+		try {
+			if (kind === "personal") {
+				await mailStore.composePersonal({
+					raceName,
+					subject,
+					body: bodyText,
+				});
+				onSent(raceName);
+				return;
+			}
+			if (kind === "broadcast") {
+				await mailStore.composeBroadcast({ subject, body: bodyText });
+				onSent(null);
+				return;
+			}
+			await mailStore.composeAdmin({
+				target: adminTarget,
+				raceName: adminTarget === "user" ? raceName : undefined,
+				recipients: adminTarget === "all" ? adminAudience : undefined,
+				subject,
+				body: bodyText,
+			});
+			onSent(null);
+		} catch (err) {
+			error = err instanceof Error ? err.message : String(err);
+		} finally {
+			sending = false;
+		}
+	}
+</script>
+
+<div class="overlay" data-testid="mail-compose">
+	<form class="dialog" onsubmit={submit}>
+		<header>
+			<h3>{i18n.t("game.mail.compose_action")}</h3>
+			<button type="button" class="close" onclick={onClose}>×</button>
+		</header>
+
+		<label>
+			{i18n.t("game.mail.compose.target_label")}
+			<select bind:value={kind} data-testid="mail-compose-kind">
+				<option value="personal">{i18n.t("game.mail.compose.target_personal")}</option>
+				<option value="broadcast">{i18n.t("game.mail.compose.target_broadcast")}</option>
+				<option value="admin">{i18n.t("game.mail.compose.target_admin")}</option>
+			</select>
+		</label>
+
+		{#if kind === "admin"}
+			<label>
+				{i18n.t("game.mail.compose.recipients_label")}
+				<select bind:value={adminTarget} data-testid="mail-compose-admin-target">
+					<option value="user">{i18n.t("game.mail.compose.target_personal")}</option>
+					<option value="all">{i18n.t("game.mail.compose.target_broadcast")}</option>
+				</select>
+			</label>
+			{#if adminTarget === "all"}
+				<label>
+					{i18n.t("game.mail.compose.recipients_label")}
+					<select bind:value={adminAudience} data-testid="mail-compose-admin-audience">
+						<option value="active">{i18n.t("game.mail.compose.recipients_active")}</option>
+						<option value="active_and_removed">{i18n.t("game.mail.compose.recipients_active_and_removed")}</option>
+						<option value="all_members">{i18n.t("game.mail.compose.recipients_all_members")}</option>
+					</select>
+				</label>
+			{/if}
+		{/if}
+
+		{#if kind === "personal" || (kind === "admin" && adminTarget === "user")}
+			<label>
+				{i18n.t("game.mail.recipient_label")}
+				<select bind:value={raceName} data-testid="mail-compose-recipient">
+					{#each races as race (race)}
+						<option value={race}>{race}</option>
+					{/each}
+				</select>
+			</label>
+		{/if}
+
+		<label>
+			<span class="visually-hidden">{i18n.t("game.mail.subject_placeholder")}</span>
+			<input
+				type="text"
+				bind:value={subject}
+				placeholder={i18n.t("game.mail.subject_placeholder")}
+				data-testid="mail-compose-subject"
+			/>
+		</label>
+
+		<label>
+			<span class="visually-hidden">{i18n.t("game.mail.body_placeholder")}</span>
+			<textarea
+				bind:value={body}
+				placeholder={i18n.t("game.mail.body_placeholder")}
+				rows="6"
+				data-testid="mail-compose-body"
+			></textarea>
+		</label>
+
+		{#if error}
+			<p class="error" data-testid="mail-compose-error">{error}</p>
+		{/if}
+
+		<footer>
+			<button type="button" onclick={onClose}>
+				{i18n.t("game.mail.compose.cancel")}
+			</button>
+			<button type="submit" disabled={sending} data-testid="mail-compose-send">
+				{i18n.t("game.mail.compose.send")}
+			</button>
+		</footer>
+	</form>
+</div>
+
+<style>
+	.overlay {
+		position: fixed;
+		inset: 0;
+		background: rgba(0, 0, 0, 0.5);
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		z-index: 50;
+	}
+	.dialog {
+		display: flex;
+		flex-direction: column;
+		gap: 0.5rem;
+		padding: 1rem 1.25rem;
+		background: #161616;
+		border: 1px solid #2a2a2a;
+		border-radius: 8px;
+		min-width: min(420px, 90vw);
+		max-width: min(560px, 95vw);
+	}
+	header {
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+	}
+	header h3 {
+		margin: 0;
+		font-size: 1rem;
+	}
+	.close {
+		font: inherit;
+		background: transparent;
+		border: none;
+		color: inherit;
+		font-size: 1.25rem;
+		cursor: pointer;
+	}
+	label {
+		display: flex;
+		flex-direction: column;
+		gap: 0.2rem;
+		font-size: 0.85rem;
+		color: #ccc;
+	}
+	input,
+	textarea,
+	select {
+		font: inherit;
+		padding: 0.4rem 0.5rem;
+		border: 1px solid #444;
+		background: #111;
+		color: inherit;
+		border-radius: 4px;
+	}
+	footer {
+		display: flex;
+		justify-content: flex-end;
+		gap: 0.5rem;
+		margin-top: 0.5rem;
+	}
+	footer button {
+		font: inherit;
+		padding: 0.35rem 0.75rem;
+		border: 1px solid #444;
+		background: #1a1a1a;
+		color: #fff;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	footer button[type="submit"] {
+		background: #2a4d7d;
+		border-color: #2a4d7d;
+	}
+	footer button:disabled {
+		opacity: 0.5;
+		cursor: not-allowed;
+	}
+	.error {
+		color: #c62828;
+		font-size: 0.85rem;
+		margin: 0;
+	}
+	.visually-hidden {
+		position: absolute;
+		clip: rect(0 0 0 0);
+		clip-path: inset(50%);
+		height: 1px;
+		width: 1px;
+		overflow: hidden;
+	}
+</style>

ui/frontend/src/lib/active-view/mail/system-item-pane.svelte

@@ -0,0 +1,106 @@
+<!--
+Phase 28 — right-pane for stand-alone messages (system mail, admin
+notifications, and the caller's own paid-tier broadcasts). The pane
+is read-only: no reply box, no per-recipient context. Soft-delete is
+available for incoming rows that the caller has read.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+
+	import { i18n } from "$lib/i18n/index.svelte";
+	import { mailStore, type MailStandalone } from "$lib/mail-store.svelte";
+	import { systemTitleKey } from "./system-titles";
+
+	let { entry }: { entry: MailStandalone } = $props();
+
+	let showOriginal = $state(false);
+
+	const incoming = $derived(entry.message.recipientUserName !== "" && entry.message.senderKind !== "player");
+
+	onMount(() => {
+		if (incoming && entry.message.readAt === null) {
+			void mailStore.markRead(entry.message.messageId);
+		}
+	});
+
+	const displayBody = $derived(
+		entry.message.translatedBody && !showOriginal
+			? entry.message.translatedBody
+			: entry.message.body,
+	);
+	const displaySubject = $derived(
+		entry.message.translatedSubject && !showOriginal
+			? entry.message.translatedSubject
+			: entry.message.subject,
+	);
+
+	const headerKey = $derived.by(() => {
+		const m = entry.message;
+		if (m.senderKind === "system") {
+			return systemTitleKey(m);
+		}
+		if (m.senderKind === "admin") {
+			return "game.mail.admin.title" as const;
+		}
+		return "game.mail.broadcast.title" as const;
+	});
+</script>
+
+<div class="standalone" data-testid="mail-system-item">
+	<h3 class="title">{i18n.t(headerKey)}</h3>
+	{#if displaySubject}
+		<div class="subject">{displaySubject}</div>
+	{/if}
+	<p class="body">{displayBody}</p>
+	{#if entry.message.translatedBody}
+		<button
+			type="button"
+			class="toggle"
+			onclick={() => (showOriginal = !showOriginal)}
+		>
+			{showOriginal ? i18n.t("game.mail.show_translation") : i18n.t("game.mail.show_original")}
+		</button>
+	{/if}
+	{#if incoming}
+		<button
+			type="button"
+			class="delete"
+			onclick={() => mailStore.softDelete(entry.message.messageId)}
+			data-testid="mail-system-delete"
+		>
+			{i18n.t("game.mail.delete_action")}
+		</button>
+	{/if}
+</div>
+
+<style>
+	.standalone {
+		display: flex;
+		flex-direction: column;
+		gap: 0.5rem;
+	}
+	.title {
+		margin: 0;
+		font-size: 1rem;
+		color: #b3a14c;
+	}
+	.subject {
+		font-weight: 700;
+	}
+	.body {
+		margin: 0;
+		white-space: pre-wrap;
+	}
+	.toggle,
+	.delete {
+		align-self: flex-start;
+		font: inherit;
+		padding: 0.2rem 0.5rem;
+		border: 1px solid #444;
+		background: transparent;
+		color: inherit;
+		border-radius: 4px;
+		cursor: pointer;
+		font-size: 0.8rem;
+	}
+</style>

ui/frontend/src/lib/active-view/mail/system-titles.ts

@@ -0,0 +1,30 @@
+// Maps a system-mail message (lifecycle hook) to its i18n title key.
+// Kept as a typed helper so the thread-list and detail panes pick the
+// same title even when the body templates evolve.
+
+import type { TranslationKey } from "$lib/i18n/index.svelte";
+import type { MailMessage } from "../../../api/diplomail";
+
+const KEYWORDS: Array<{ test: RegExp; key: TranslationKey }> = [
+	{ test: /game[._ ]paused/i, key: "game.mail.system.game_paused.title" },
+	{ test: /game[._ ]cancelled|cancelled/i, key: "game.mail.system.game_cancelled.title" },
+	{ test: /membership[._ ]removed|kicked/i, key: "game.mail.system.membership_removed.title" },
+	{ test: /membership[._ ]blocked|blocked/i, key: "game.mail.system.membership_blocked.title" },
+];
+
+/**
+ * systemTitleKey returns the localised title key for a system mail
+ * row. The lobby renders these messages through templated subjects;
+ * the UI matches on the subject to pick a canonical title regardless
+ * of language. Falls back to a generic system-mail title when no
+ * pattern matches.
+ */
+export function systemTitleKey(message: MailMessage): TranslationKey {
+	const subject = message.subject ?? "";
+	for (const { test, key } of KEYWORDS) {
+		if (test.test(subject)) {
+			return key;
+		}
+	}
+	return "game.mail.system.generic.title";
+}

ui/frontend/src/lib/active-view/mail/thread-list.svelte

@@ -0,0 +1,130 @@
+<!--
+Phase 28 — left-pane list of mail entries. Each entry is either a
+per-race thread (collapsed to the latest message) or a stand-alone
+system / admin / outgoing-broadcast item. The list is virtual only
+inside its scroll container; PixiJS / canvas concerns do not apply
+here.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+	import type { MailListEntry } from "$lib/mail-store.svelte";
+	import { systemTitleKey } from "./system-titles";
+
+	let {
+		entries,
+		selectedKey,
+		onSelect,
+	}: {
+		entries: MailListEntry[];
+		selectedKey: string | null;
+		onSelect: (entry: MailListEntry) => void;
+	} = $props();
+
+	function entryKey(entry: MailListEntry): string {
+		return entry.kind === "thread"
+			? `thread:${entry.raceName}`
+			: `standalone:${entry.message.messageId}`;
+	}
+
+	function snippet(entry: MailListEntry): string {
+		if (entry.kind === "thread") {
+			const last = entry.messages[entry.messages.length - 1];
+			return last.subject || last.body;
+		}
+		return entry.message.subject || entry.message.body;
+	}
+</script>
+
+<ul class="list" data-testid="mail-thread-list">
+	{#each entries as entry (entryKey(entry))}
+		<li
+			class="row"
+			class:active={selectedKey === entryKey(entry)}
+			class:standalone={entry.kind === "standalone"}
+			class:has-unread={entry.kind === "thread" && entry.unreadCount > 0}
+			data-testid="mail-list-row"
+		>
+			<button
+				type="button"
+				class="row-btn"
+				onclick={() => onSelect(entry)}
+				data-thread-key={entryKey(entry)}
+			>
+				<span class="title">
+					{#if entry.kind === "thread"}
+						{entry.raceName}
+					{:else if entry.message.senderKind === "system"}
+						{i18n.t(systemTitleKey(entry.message))}
+					{:else if entry.message.senderKind === "admin"}
+						{i18n.t("game.mail.admin.title")}
+					{:else}
+						{i18n.t("game.mail.broadcast.title")}
+					{/if}
+				</span>
+				{#if entry.kind === "thread" && entry.unreadCount > 0}
+					<span class="badge" data-testid="mail-row-unread">{entry.unreadCount}</span>
+				{/if}
+				<span class="snippet">{snippet(entry)}</span>
+			</button>
+		</li>
+	{/each}
+</ul>
+
+<style>
+	.list {
+		list-style: none;
+		margin: 0;
+		padding: 0;
+		display: flex;
+		flex-direction: column;
+		gap: 0.25rem;
+	}
+	.row-btn {
+		display: grid;
+		grid-template-columns: 1fr auto;
+		grid-template-rows: auto auto;
+		gap: 0.25rem 0.5rem;
+		text-align: left;
+		width: 100%;
+		padding: 0.5rem 0.75rem;
+		font: inherit;
+		background: transparent;
+		color: inherit;
+		border: 1px solid transparent;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.row.active .row-btn {
+		border-color: #555;
+		background: #1c1c1c;
+	}
+	.row.has-unread .title {
+		font-weight: 700;
+	}
+	.row.standalone .title {
+		color: #b3a14c;
+	}
+	.title {
+		grid-column: 1 / span 1;
+	}
+	.badge {
+		grid-column: 2 / span 1;
+		grid-row: 1 / span 1;
+		justify-self: end;
+		min-width: 1.5rem;
+		padding: 0 0.4rem;
+		text-align: center;
+		font-size: 0.75rem;
+		border-radius: 999px;
+		background: #2a4d7d;
+		color: #fff;
+	}
+	.snippet {
+		grid-column: 1 / span 2;
+		color: #999;
+		font-size: 0.85rem;
+		overflow: hidden;
+		text-overflow: ellipsis;
+		white-space: nowrap;
+	}
+</style>

ui/frontend/src/lib/active-view/mail/thread-pane.svelte

@@ -0,0 +1,255 @@
+<!--
+Phase 28 — right-pane transcript for a single per-race thread.
+Renders messages oldest → newest, with outgoing messages visually
+distinct from incoming. Each message body goes through `textContent`
+(no HTML parsing); the optional translation has a per-message
+"show original" / "show translation" toggle. A persistent reply box
+sits at the bottom of the pane.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+
+	import { i18n } from "$lib/i18n/index.svelte";
+	import { mailStore, type MailThread } from "$lib/mail-store.svelte";
+	import type { MailMessage } from "../../../api/diplomail";
+
+	let {
+		thread,
+		gameId,
+	}: {
+		thread: MailThread;
+		gameId: string;
+	} = $props();
+
+	let replyBody = $state("");
+	let replyError = $state<string | null>(null);
+	let sending = $state(false);
+	const showOriginal = $state<Map<string, boolean>>(new Map());
+
+	// Mark every still-unread incoming message in this thread as read
+	// when the pane mounts. Idempotent on the server; the store
+	// optimistically flips `readAt` so the header badge updates
+	// without waiting for the round-trip.
+	onMount(() => {
+		for (const m of thread.messages) {
+			const incoming = m.senderRaceName === thread.raceName;
+			if (incoming && m.readAt === null) {
+				void mailStore.markRead(m.messageId);
+			}
+		}
+	});
+
+	function isOutgoing(m: MailMessage): boolean {
+		// Outgoing messages have the local user as sender, which
+		// corresponds to `recipientRaceName === thread.raceName` (the
+		// thread is keyed on the other party's race name).
+		return m.recipientRaceName === thread.raceName;
+	}
+
+	function displayBody(m: MailMessage): string {
+		if (m.translatedBody && !showOriginal.get(m.messageId)) {
+			return m.translatedBody;
+		}
+		return m.body;
+	}
+
+	function displaySubject(m: MailMessage): string {
+		if (m.translatedSubject && !showOriginal.get(m.messageId)) {
+			return m.translatedSubject ?? "";
+		}
+		return m.subject;
+	}
+
+	function toggleTranslation(messageId: string): void {
+		showOriginal.set(messageId, !(showOriginal.get(messageId) ?? false));
+		// Trigger reactivity on the map proxy.
+		showOriginal.size; // eslint-disable-line @typescript-eslint/no-unused-expressions
+	}
+
+	async function submitReply(event: SubmitEvent): Promise<void> {
+		event.preventDefault();
+		replyError = null;
+		const body = replyBody.trim();
+		if (body === "") {
+			replyError = i18n.t("game.mail.body_required");
+			return;
+		}
+		sending = true;
+		try {
+			await mailStore.composePersonal({
+				raceName: thread.raceName,
+				subject: "",
+				body,
+			});
+			replyBody = "";
+		} catch (err) {
+			replyError = err instanceof Error ? err.message : String(err);
+		} finally {
+			sending = false;
+		}
+	}
+
+	$effect(() => {
+		// Force the component to depend on the gameId rune so a game
+		// switch re-mounts the pane (the parent unmounts the old one
+		// implicitly via the entry-key change, but this keeps the
+		// dependency explicit for SSR-disabled hot reloads).
+		void gameId;
+	});
+</script>
+
+<div class="thread" data-testid="mail-thread-pane">
+	<h3 class="title">{thread.raceName}</h3>
+	<ol class="messages">
+		{#each thread.messages as m (m.messageId)}
+			<li class="message" class:outgoing={isOutgoing(m)}>
+				<div class="meta">
+					<span class="from">
+						{#if isOutgoing(m)}
+							{i18n.t("game.mail.outgoing_label")}
+						{:else}
+							{thread.raceName}
+						{/if}
+					</span>
+					<time>{m.createdAt.toISOString().slice(0, 19).replace("T", " ")}</time>
+				</div>
+				{#if displaySubject(m)}
+					<div class="subject">{displaySubject(m)}</div>
+				{/if}
+				<p class="body">{displayBody(m)}</p>
+				{#if m.translatedBody}
+					<button
+						type="button"
+						class="toggle"
+						onclick={() => toggleTranslation(m.messageId)}
+					>
+						{#if showOriginal.get(m.messageId)}
+							{i18n.t("game.mail.show_translation")}
+						{:else}
+							{i18n.t("game.mail.show_original")}
+						{/if}
+					</button>
+				{/if}
+				{#if !isOutgoing(m)}
+					<button
+						type="button"
+						class="delete"
+						onclick={() => mailStore.softDelete(m.messageId)}
+						data-testid="mail-delete"
+					>
+						{i18n.t("game.mail.delete_action")}
+					</button>
+				{/if}
+			</li>
+		{/each}
+	</ol>
+
+	<form class="reply" onsubmit={submitReply}>
+		<label for="mail-reply-body">{i18n.t("game.mail.reply_label")}</label>
+		<textarea
+			id="mail-reply-body"
+			bind:value={replyBody}
+			placeholder={i18n.t("game.mail.body_placeholder")}
+			rows="3"
+			data-testid="mail-reply-body"
+		></textarea>
+		{#if replyError}
+			<p class="error" data-testid="mail-reply-error">{replyError}</p>
+		{/if}
+		<button type="submit" disabled={sending} data-testid="mail-reply-send">
+			{i18n.t("game.mail.compose.send")}
+		</button>
+	</form>
+</div>
+
+<style>
+	.thread {
+		display: flex;
+		flex-direction: column;
+		gap: 0.75rem;
+		height: 100%;
+	}
+	.title {
+		margin: 0;
+		font-size: 1rem;
+	}
+	.messages {
+		list-style: none;
+		margin: 0;
+		padding: 0;
+		display: flex;
+		flex-direction: column;
+		gap: 0.5rem;
+		overflow-y: auto;
+		max-height: 50vh;
+	}
+	.message {
+		padding: 0.5rem 0.75rem;
+		border-radius: 6px;
+		background: #1c1c1c;
+		border: 1px solid #2a2a2a;
+	}
+	.message.outgoing {
+		background: #15252e;
+	}
+	.meta {
+		display: flex;
+		justify-content: space-between;
+		font-size: 0.8rem;
+		color: #999;
+		margin-bottom: 0.25rem;
+	}
+	.subject {
+		font-weight: 700;
+	}
+	.body {
+		margin: 0.25rem 0 0;
+		white-space: pre-wrap;
+	}
+	.toggle,
+	.delete {
+		margin-top: 0.5rem;
+		margin-right: 0.5rem;
+		font: inherit;
+		padding: 0.2rem 0.5rem;
+		border: 1px solid #444;
+		background: transparent;
+		color: inherit;
+		border-radius: 4px;
+		cursor: pointer;
+		font-size: 0.8rem;
+	}
+	.reply {
+		display: flex;
+		flex-direction: column;
+		gap: 0.25rem;
+	}
+	.reply textarea {
+		font: inherit;
+		padding: 0.5rem;
+		border: 1px solid #444;
+		background: #111;
+		color: inherit;
+		border-radius: 4px;
+		resize: vertical;
+	}
+	.reply button {
+		align-self: flex-end;
+		font: inherit;
+		padding: 0.35rem 0.75rem;
+		border: 1px solid #444;
+		background: #1a1a1a;
+		color: #fff;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.reply button:disabled {
+		opacity: 0.5;
+		cursor: not-allowed;
+	}
+	.error {
+		color: #c62828;
+		font-size: 0.85rem;
+		margin: 0;
+	}
+</style>

ui/frontend/src/lib/header/view-menu.svelte

@@ -15,10 +15,13 @@ polishes microcopy.
 	import { onMount } from "svelte";
 	import { goto } from "$app/navigation";
 	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+	import { mailStore } from "$lib/mail-store.svelte";
 
 	type Props = { gameId: string };
 	let { gameId }: Props = $props();
 
+	const mailUnread = $derived(mailStore.unreadCount);
+
 	let open = $state(false);
 	let rootEl: HTMLDivElement | null = $state(null);
 
@@ -122,9 +125,15 @@ polishes microcopy.
 				type="button"
 				role="menuitem"
 				data-testid="view-menu-item-mail"
+				class="with-badge"
 				onclick={() => go(`/games/${gameId}/mail`)}
 			>
-				{i18n.t("game.view.mail")}
+				<span>{i18n.t("game.view.mail")}</span>
+				{#if mailUnread > 0}
+					<span class="badge" data-testid="view-menu-item-mail-badge">
+						{i18n.t("game.view.mail.badge", { count: String(mailUnread) })}
+					</span>
+				{/if}
 			</button>
 			<button
 				type="button"
@@ -200,6 +209,21 @@ polishes microcopy.
 		border: 0;
 		cursor: pointer;
 	}
+	.surface > button.with-badge {
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+		gap: 0.5rem;
+	}
+	.surface > button.with-badge .badge {
+		min-width: 1.5rem;
+		padding: 0 0.4rem;
+		text-align: center;
+		font-size: 0.75rem;
+		border-radius: 999px;
+		background: #2a4d7d;
+		color: #fff;
+	}
 	.surface > button:hover,
 	.surface > details > summary:hover {
 		background: #1c2238;

ui/frontend/src/lib/i18n/locales/en.ts

@@ -123,6 +123,46 @@ const en = {
 	"game.view.report": "turn report",
 	"game.view.battle": "battle log",
 	"game.view.mail": "diplomatic mail",
+	"game.view.mail.badge": "{count}",
+	"game.events.mail_new.message": "new mail from {from}",
+	"game.events.mail_new.action": "view",
+	"game.mail.loading": "loading mail…",
+	"game.mail.load_failed": "could not load mail",
+	"game.mail.empty": "no diplomatic messages yet",
+	"game.mail.back": "back",
+	"game.mail.compose_action": "compose",
+	"game.mail.select_thread": "pick a thread on the left to read it",
+	"game.mail.broadcast.title": "your broadcast",
+	"game.mail.admin.title": "admin notification",
+	"game.mail.system.generic.title": "system message",
+	"game.mail.system.game_paused.title": "game paused",
+	"game.mail.system.game_cancelled.title": "game cancelled",
+	"game.mail.system.membership_removed.title": "membership removed",
+	"game.mail.system.membership_blocked.title": "membership blocked",
+	"game.mail.subject_placeholder": "subject (optional)",
+	"game.mail.body_placeholder": "your message…",
+	"game.mail.recipient_label": "race",
+	"game.mail.recipient_required": "pick a recipient race",
+	"game.mail.body_required": "the message body cannot be empty",
+	"game.mail.body_too_long": "the body exceeds the {limit} byte limit",
+	"game.mail.subject_too_long": "the subject exceeds the {limit} byte limit",
+	"game.mail.compose.send": "send",
+	"game.mail.compose.cancel": "cancel",
+	"game.mail.compose.target_personal": "personal",
+	"game.mail.compose.target_broadcast": "broadcast",
+	"game.mail.compose.target_admin": "admin",
+	"game.mail.compose.recipients_active": "active members",
+	"game.mail.compose.recipients_active_and_removed": "active + removed",
+	"game.mail.compose.recipients_all_members": "all members",
+	"game.mail.compose.target_label": "kind",
+	"game.mail.compose.recipients_label": "audience",
+	"game.mail.compose.send_failed": "send failed",
+	"game.mail.show_original": "show original",
+	"game.mail.show_translation": "show translation",
+	"game.mail.translation_unavailable": "translation unavailable",
+	"game.mail.reply_label": "reply",
+	"game.mail.delete_action": "delete",
+	"game.mail.outgoing_label": "you",
 	"game.view.designer.ship_class": "ship-class designer",
 	"game.view.designer.science": "science designer",
 	"game.sidebar.tab.calculator": "calculator",

ui/frontend/src/lib/i18n/locales/ru.ts

@@ -124,6 +124,46 @@ const ru: Record<keyof typeof en, string> = {
 	"game.view.report": "отчёт хода",
 	"game.view.battle": "журнал боёв",
 	"game.view.mail": "дипломатическая почта",
+	"game.view.mail.badge": "{count}",
+	"game.events.mail_new.message": "новое письмо от {from}",
+	"game.events.mail_new.action": "открыть",
+	"game.mail.loading": "загрузка почты…",
+	"game.mail.load_failed": "не удалось загрузить почту",
+	"game.mail.empty": "дипломатических сообщений пока нет",
+	"game.mail.back": "назад",
+	"game.mail.compose_action": "написать",
+	"game.mail.select_thread": "выбери ветку слева",
+	"game.mail.broadcast.title": "твоя рассылка",
+	"game.mail.admin.title": "административное уведомление",
+	"game.mail.system.generic.title": "системное сообщение",
+	"game.mail.system.game_paused.title": "игра поставлена на паузу",
+	"game.mail.system.game_cancelled.title": "игра отменена",
+	"game.mail.system.membership_removed.title": "членство удалено",
+	"game.mail.system.membership_blocked.title": "членство заблокировано",
+	"game.mail.subject_placeholder": "тема (необязательно)",
+	"game.mail.body_placeholder": "твоё сообщение…",
+	"game.mail.recipient_label": "раса",
+	"game.mail.recipient_required": "выбери расу-получателя",
+	"game.mail.body_required": "тело сообщения не может быть пустым",
+	"game.mail.body_too_long": "длина тела превышает лимит {limit} байт",
+	"game.mail.subject_too_long": "длина темы превышает лимит {limit} байт",
+	"game.mail.compose.send": "отправить",
+	"game.mail.compose.cancel": "отмена",
+	"game.mail.compose.target_personal": "личное",
+	"game.mail.compose.target_broadcast": "рассылка",
+	"game.mail.compose.target_admin": "админ.",
+	"game.mail.compose.recipients_active": "активным членам",
+	"game.mail.compose.recipients_active_and_removed": "активным + удалённым",
+	"game.mail.compose.recipients_all_members": "всем членам",
+	"game.mail.compose.target_label": "тип",
+	"game.mail.compose.recipients_label": "адресаты",
+	"game.mail.compose.send_failed": "отправка не удалась",
+	"game.mail.show_original": "показать оригинал",
+	"game.mail.show_translation": "показать перевод",
+	"game.mail.translation_unavailable": "перевод недоступен",
+	"game.mail.reply_label": "ответить",
+	"game.mail.delete_action": "удалить",
+	"game.mail.outgoing_label": "ты",
 	"game.view.designer.ship_class": "конструктор класса кораблей",
 	"game.view.designer.science": "редактор наук",
 	"game.sidebar.tab.calculator": "калькулятор",

ui/frontend/src/lib/mail-store.svelte.ts

@@ -0,0 +1,373 @@
+// Phase 28 reactive store for the in-game diplomatic-mail view. Owns
+// the inbox / sent listings, the per-race threading projection, the
+// unread badge counter, and the imperative compose / mark-read /
+// delete actions. The companion API wrappers live in
+// `src/api/diplomail.ts`; this store coordinates them with the rest
+// of the in-game shell.
+
+import type { GalaxyClient } from "../api/galaxy-client";
+import type { Cache } from "../platform/store/index";
+import {
+	deleteMessage,
+	fetchInbox,
+	fetchMessage,
+	fetchSent,
+	markRead,
+	sendAdmin,
+	sendBroadcast,
+	sendPersonal,
+	type MailMessage,
+	type SendAdminArgs,
+	type SendBroadcastArgs,
+	type SendPersonalArgs,
+} from "../api/diplomail";
+
+/**
+ * MailThread groups personal messages exchanged with a single other
+ * race into one entry. The local player's outgoing messages live
+ * alongside incoming messages from the same race so the UI renders a
+ * chat-style transcript. `unreadCount` counts only incoming messages
+ * with `readAt === null`.
+ */
+export interface MailThread {
+	kind: "thread";
+	raceName: string;
+	messages: MailMessage[];
+	unreadCount: number;
+	latestAt: Date;
+}
+
+/**
+ * MailStandalone wraps a single message that does not participate in
+ * a race-thread: system mail, admin notifications, and the caller's
+ * own paid-tier broadcasts. The UI renders these as read-only items
+ * in the same list as the per-race threads.
+ */
+export interface MailStandalone {
+	kind: "standalone";
+	message: MailMessage;
+	latestAt: Date;
+}
+
+export type MailListEntry = MailThread | MailStandalone;
+
+const CACHE_NAMESPACE = "diplomail";
+
+/**
+ * MailStore is the reactive surface consumed by the active view, the
+ * header badge, and the push-event handler. One instance per signed-
+ * in session is enough — the rune fields are scoped to the current
+ * game and replaced on every `setGame` call so navigating between
+ * games stays clean.
+ */
+export class MailStore {
+	gameId = $state("");
+	status: "idle" | "loading" | "ready" | "error" = $state("idle");
+	error: string | null = $state(null);
+	inbox: MailMessage[] = $state([]);
+	sent: MailMessage[] = $state([]);
+
+	private client: GalaxyClient | null = null;
+	private cache: Cache | null = null;
+
+	/**
+	 * entries surfaces the unified list-pane projection: per-race
+	 * threads built from incoming + outgoing personal messages plus
+	 * stand-alone items for system / admin / own-broadcast rows.
+	 * Sorted newest-first by the latest message inside each entry.
+	 */
+	entries: MailListEntry[] = $derived.by(() => buildEntries(this.inbox, this.sent));
+
+	/**
+	 * unreadCount drives the header view-menu badge. Counts only
+	 * incoming personal / admin / system messages with `readAt === null`.
+	 * `read_at` is not surfaced to the user in the UI but still
+	 * drives this counter.
+	 */
+	unreadCount = $derived.by(() => this.inbox.reduce((acc, m) => (m.readAt === null ? acc + 1 : acc), 0));
+
+	/**
+	 * init configures the dependencies and fires the initial fetch.
+	 * Safe to call multiple times — calls after the first one are
+	 * routed to `setGame`. `localUserId` is captured so the threading
+	 * projection can tell outgoing messages from incoming when the
+	 * inbox and sent lists are unified.
+	 */
+	async init(opts: {
+		client: GalaxyClient;
+		cache: Cache;
+		gameId: string;
+	}): Promise<void> {
+		this.client = opts.client;
+		this.cache = opts.cache;
+		await this.setGame(opts.gameId);
+	}
+
+	/**
+	 * setGame switches the store to a different game id and refreshes
+	 * its inbox / sent state. Idempotent on the same id — the network
+	 * fetch fires only when the id actually changed or the previous
+	 * load ended in `error`.
+	 */
+	async setGame(gameId: string): Promise<void> {
+		if (this.client === null) {
+			throw new Error("mail-store: setGame called before init");
+		}
+		if (this.gameId === gameId && this.status === "ready") {
+			return;
+		}
+		this.gameId = gameId;
+		this.status = "loading";
+		this.error = null;
+		this.inbox = [];
+		this.sent = [];
+		try {
+			const [inbox, sent] = await Promise.all([
+				fetchInbox(this.client, gameId),
+				fetchSent(this.client, gameId),
+			]);
+			this.inbox = inbox;
+			this.sent = sent;
+			this.status = "ready";
+			await this.rememberLastSeen();
+		} catch (err) {
+			this.status = "error";
+			this.error = errorMessage(err);
+		}
+	}
+
+	/** refresh re-fetches inbox + sent for the active game. */
+	async refresh(): Promise<void> {
+		if (this.gameId === "") {
+			return;
+		}
+		await this.setGame(this.gameId);
+	}
+
+	/**
+	 * applyPushEvent reacts to a verified `diplomail.message.received`
+	 * push frame by refetching the inbox for the active game. The
+	 * payload carries only a preview, so the store hits the server for
+	 * the canonical row.
+	 */
+	async applyPushEvent(payloadGameId: string): Promise<void> {
+		if (payloadGameId !== this.gameId || this.client === null) {
+			return;
+		}
+		try {
+			this.inbox = await fetchInbox(this.client, this.gameId);
+			await this.rememberLastSeen();
+		} catch (err) {
+			this.error = errorMessage(err);
+		}
+	}
+
+	/**
+	 * markRead transitions an incoming message to `read`. The local
+	 * inbox row is flipped optimistically; on failure the previous
+	 * state is restored and the error surfaces via `error`.
+	 */
+	async markRead(messageId: string): Promise<void> {
+		if (this.client === null) {
+			return;
+		}
+		const before = this.inbox;
+		this.inbox = before.map((m) => {
+			if (m.messageId !== messageId) {
+				return m;
+			}
+			return { ...m, readAt: m.readAt ?? new Date() };
+		});
+		try {
+			await markRead(this.client, this.gameId, messageId);
+		} catch (err) {
+			this.inbox = before;
+			this.error = errorMessage(err);
+		}
+	}
+
+	/**
+	 * softDelete removes a read incoming message from the inbox. The
+	 * server enforces "read before delete"; on conflict the row is
+	 * restored and the error surfaces.
+	 */
+	async softDelete(messageId: string): Promise<void> {
+		if (this.client === null) {
+			return;
+		}
+		const before = this.inbox;
+		this.inbox = before.filter((m) => m.messageId !== messageId);
+		try {
+			await deleteMessage(this.client, this.gameId, messageId);
+		} catch (err) {
+			this.inbox = before;
+			this.error = errorMessage(err);
+		}
+	}
+
+	/**
+	 * composePersonal sends a single-recipient personal message,
+	 * addressed by race name (resolved server-side). On success the
+	 * resulting row is appended to the sent list so the matching
+	 * thread surfaces it immediately. Throws on failure so callers
+	 * can render inline form errors.
+	 */
+	async composePersonal(input: Omit<SendPersonalArgs, "gameId">): Promise<MailMessage> {
+		if (this.client === null) {
+			throw new Error("mail-store: composePersonal called before init");
+		}
+		const created = await sendPersonal(this.client, { ...input, gameId: this.gameId });
+		this.sent = [created, ...this.sent];
+		return created;
+	}
+
+	/**
+	 * composeBroadcast posts a paid-tier player broadcast. The sent
+	 * list is refreshed to surface the new entries.
+	 */
+	async composeBroadcast(input: Omit<SendBroadcastArgs, "gameId">): Promise<void> {
+		if (this.client === null) {
+			throw new Error("mail-store: composeBroadcast called before init");
+		}
+		await sendBroadcast(this.client, { ...input, gameId: this.gameId });
+		this.sent = await fetchSent(this.client, this.gameId);
+	}
+
+	/**
+	 * composeAdmin posts an owner-only admin notification. Single
+	 * sends refresh the sent list; broadcasts also refresh the sent
+	 * list (the author does not appear as a recipient and is excluded
+	 * from the resulting fan-out).
+	 */
+	async composeAdmin(input: Omit<SendAdminArgs, "gameId">): Promise<void> {
+		if (this.client === null) {
+			throw new Error("mail-store: composeAdmin called before init");
+		}
+		await sendAdmin(this.client, { ...input, gameId: this.gameId });
+		this.sent = await fetchSent(this.client, this.gameId);
+	}
+
+	/**
+	 * loadMessage fetches a single message detail (used when the UI
+	 * needs the freshest translation status for a specific row).
+	 * The returned row is merged into the inbox copy if it lives
+	 * there; sent rows are not refreshed here.
+	 */
+	async loadMessage(messageId: string): Promise<MailMessage | null> {
+		if (this.client === null) {
+			return null;
+		}
+		try {
+			const fresh = await fetchMessage(this.client, this.gameId, messageId);
+			this.inbox = this.inbox.map((m) => (m.messageId === messageId ? fresh : m));
+			return fresh;
+		} catch (err) {
+			this.error = errorMessage(err);
+			return null;
+		}
+	}
+
+	private async rememberLastSeen(): Promise<void> {
+		if (this.cache === null || this.gameId === "" || this.inbox.length === 0) {
+			return;
+		}
+		const last = this.inbox[0];
+		await this.cache.put(CACHE_NAMESPACE, `${this.gameId}/last-seen`, last.messageId);
+	}
+}
+
+function buildEntries(inbox: MailMessage[], sent: MailMessage[]): MailListEntry[] {
+	// Each personal message keyed by another race contributes to a
+	// race thread. Other shapes become stand-alone entries.
+	const threadsByRace = new Map<string, MailThread>();
+	const standalones: MailStandalone[] = [];
+
+	for (const m of inbox) {
+		if (isStandaloneIncoming(m)) {
+			standalones.push({ kind: "standalone", message: m, latestAt: m.createdAt });
+			continue;
+		}
+		const race = m.senderRaceName ?? "";
+		if (race === "") {
+			standalones.push({ kind: "standalone", message: m, latestAt: m.createdAt });
+			continue;
+		}
+		mergeIntoThread(threadsByRace, race, m, /*isIncoming=*/true);
+	}
+
+	for (const m of sent) {
+		if (isStandaloneOutgoing(m)) {
+			standalones.push({ kind: "standalone", message: m, latestAt: m.createdAt });
+			continue;
+		}
+		const race = m.recipientRaceName ?? "";
+		if (race === "") {
+			standalones.push({ kind: "standalone", message: m, latestAt: m.createdAt });
+			continue;
+		}
+		mergeIntoThread(threadsByRace, race, m, /*isIncoming=*/false);
+	}
+
+	// Sort each thread's messages oldest → newest for chat-style
+	// rendering; the entry list itself sorts newest-first by the
+	// most-recent message timestamp.
+	for (const thread of threadsByRace.values()) {
+		thread.messages.sort((a, b) => a.createdAt.getTime() - b.createdAt.getTime());
+		const last = thread.messages[thread.messages.length - 1];
+		thread.latestAt = last.createdAt;
+	}
+
+	const entries: MailListEntry[] = [
+		...Array.from(threadsByRace.values()),
+		...standalones,
+	];
+	entries.sort((a, b) => b.latestAt.getTime() - a.latestAt.getTime());
+	return entries;
+}
+
+function mergeIntoThread(
+	threads: Map<string, MailThread>,
+	race: string,
+	message: MailMessage,
+	isIncoming: boolean,
+): void {
+	let thread = threads.get(race);
+	if (thread === undefined) {
+		thread = {
+			kind: "thread",
+			raceName: race,
+			messages: [],
+			unreadCount: 0,
+			latestAt: message.createdAt,
+		};
+		threads.set(race, thread);
+	}
+	thread.messages.push(message);
+	if (isIncoming && message.readAt === null) {
+		thread.unreadCount += 1;
+	}
+	if (message.createdAt.getTime() > thread.latestAt.getTime()) {
+		thread.latestAt = message.createdAt;
+	}
+}
+
+function isStandaloneIncoming(m: MailMessage): boolean {
+	// System / admin notifications never thread by race even when a
+	// snapshot is available — they are one-way operational mail.
+	return m.senderKind !== "player";
+}
+
+function isStandaloneOutgoing(m: MailMessage): boolean {
+	// Paid-tier broadcasts that the caller authored target many
+	// recipients; the UI renders them once as a stand-alone item.
+	return m.broadcastScope !== "single";
+}
+
+function errorMessage(err: unknown): string {
+	if (err instanceof Error) {
+		return err.message;
+	}
+	return String(err);
+}
+
+export const mailStore = new MailStore();

ui/frontend/src/proto/galaxy/fbs/diplomail.ts

@@ -0,0 +1,23 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+export { AdminRequest, AdminRequestT } from './diplomail/admin-request.js';
+export { AdminResponse, AdminResponseT } from './diplomail/admin-response.js';
+export { BroadcastRequest, BroadcastRequestT } from './diplomail/broadcast-request.js';
+export { BroadcastResponse, BroadcastResponseT } from './diplomail/broadcast-response.js';
+export { DeleteRequest, DeleteRequestT } from './diplomail/delete-request.js';
+export { DeleteResponse, DeleteResponseT } from './diplomail/delete-response.js';
+export { InboxRequest, InboxRequestT } from './diplomail/inbox-request.js';
+export { InboxResponse, InboxResponseT } from './diplomail/inbox-response.js';
+export { MailBroadcastReceipt, MailBroadcastReceiptT } from './diplomail/mail-broadcast-receipt.js';
+export { MailMessage, MailMessageT } from './diplomail/mail-message.js';
+export { MailRecipientState, MailRecipientStateT } from './diplomail/mail-recipient-state.js';
+export { MessageGetRequest, MessageGetRequestT } from './diplomail/message-get-request.js';
+export { MessageGetResponse, MessageGetResponseT } from './diplomail/message-get-response.js';
+export { ReadRequest, ReadRequestT } from './diplomail/read-request.js';
+export { ReadResponse, ReadResponseT } from './diplomail/read-response.js';
+export { SendRequest, SendRequestT } from './diplomail/send-request.js';
+export { SendResponse, SendResponseT } from './diplomail/send-response.js';
+export { SentRequest, SentRequestT } from './diplomail/sent-request.js';
+export { SentResponse, SentResponseT } from './diplomail/sent-response.js';

ui/frontend/src/proto/galaxy/fbs/diplomail/admin-request.ts

@@ -0,0 +1,179 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class AdminRequest implements flatbuffers.IUnpackableObject<AdminRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):AdminRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsAdminRequest(bb:flatbuffers.ByteBuffer, obj?:AdminRequest):AdminRequest {
+  return (obj || new AdminRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsAdminRequest(bb:flatbuffers.ByteBuffer, obj?:AdminRequest):AdminRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new AdminRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+target():string|null
+target(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+target(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipientUserId():string|null
+recipientUserId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientUserId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipientRaceName():string|null
+recipientRaceName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientRaceName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 10);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipients():string|null
+recipients(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipients(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 12);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+subject():string|null
+subject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+subject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 14);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+body():string|null
+body(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+body(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+static startAdminRequest(builder:flatbuffers.Builder) {
+  builder.startObject(7);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addTarget(builder:flatbuffers.Builder, targetOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, targetOffset, 0);
+}
+
+static addRecipientUserId(builder:flatbuffers.Builder, recipientUserIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, recipientUserIdOffset, 0);
+}
+
+static addRecipientRaceName(builder:flatbuffers.Builder, recipientRaceNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(3, recipientRaceNameOffset, 0);
+}
+
+static addRecipients(builder:flatbuffers.Builder, recipientsOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(4, recipientsOffset, 0);
+}
+
+static addSubject(builder:flatbuffers.Builder, subjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(5, subjectOffset, 0);
+}
+
+static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(6, bodyOffset, 0);
+}
+
+static endAdminRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  return offset;
+}
+
+static createAdminRequest(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset, targetOffset:flatbuffers.Offset, recipientUserIdOffset:flatbuffers.Offset, recipientRaceNameOffset:flatbuffers.Offset, recipientsOffset:flatbuffers.Offset, subjectOffset:flatbuffers.Offset, bodyOffset:flatbuffers.Offset):flatbuffers.Offset {
+  AdminRequest.startAdminRequest(builder);
+  AdminRequest.addGameId(builder, gameIdOffset);
+  AdminRequest.addTarget(builder, targetOffset);
+  AdminRequest.addRecipientUserId(builder, recipientUserIdOffset);
+  AdminRequest.addRecipientRaceName(builder, recipientRaceNameOffset);
+  AdminRequest.addRecipients(builder, recipientsOffset);
+  AdminRequest.addSubject(builder, subjectOffset);
+  AdminRequest.addBody(builder, bodyOffset);
+  return AdminRequest.endAdminRequest(builder);
+}
+
+unpack(): AdminRequestT {
+  return new AdminRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    this.target(),
+    this.recipientUserId(),
+    this.recipientRaceName(),
+    this.recipients(),
+    this.subject(),
+    this.body()
+  );
+}
+
+
+unpackTo(_o: AdminRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.target = this.target();
+  _o.recipientUserId = this.recipientUserId();
+  _o.recipientRaceName = this.recipientRaceName();
+  _o.recipients = this.recipients();
+  _o.subject = this.subject();
+  _o.body = this.body();
+}
+}
+
+export class AdminRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public target: string|Uint8Array|null = null,
+  public recipientUserId: string|Uint8Array|null = null,
+  public recipientRaceName: string|Uint8Array|null = null,
+  public recipients: string|Uint8Array|null = null,
+  public subject: string|Uint8Array|null = null,
+  public body: string|Uint8Array|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const target = (this.target !== null ? builder.createString(this.target!) : 0);
+  const recipientUserId = (this.recipientUserId !== null ? builder.createString(this.recipientUserId!) : 0);
+  const recipientRaceName = (this.recipientRaceName !== null ? builder.createString(this.recipientRaceName!) : 0);
+  const recipients = (this.recipients !== null ? builder.createString(this.recipients!) : 0);
+  const subject = (this.subject !== null ? builder.createString(this.subject!) : 0);
+  const body = (this.body !== null ? builder.createString(this.body!) : 0);
+
+  return AdminRequest.createAdminRequest(builder,
+    (this.gameId !== null ? this.gameId!.pack(builder) : 0),
+    target,
+    recipientUserId,
+    recipientRaceName,
+    recipients,
+    subject,
+    body
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/admin-response.ts

@@ -0,0 +1,88 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailBroadcastReceipt, MailBroadcastReceiptT } from '../diplomail/mail-broadcast-receipt.js';
+import { MailMessage, MailMessageT } from '../diplomail/mail-message.js';
+
+
+export class AdminResponse implements flatbuffers.IUnpackableObject<AdminResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):AdminResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsAdminResponse(bb:flatbuffers.ByteBuffer, obj?:AdminResponse):AdminResponse {
+  return (obj || new AdminResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsAdminResponse(bb:flatbuffers.ByteBuffer, obj?:AdminResponse):AdminResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new AdminResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+message(obj?:MailMessage):MailMessage|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailMessage()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+receipt(obj?:MailBroadcastReceipt):MailBroadcastReceipt|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? (obj || new MailBroadcastReceipt()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startAdminResponse(builder:flatbuffers.Builder) {
+  builder.startObject(2);
+}
+
+static addMessage(builder:flatbuffers.Builder, messageOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageOffset, 0);
+}
+
+static addReceipt(builder:flatbuffers.Builder, receiptOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, receiptOffset, 0);
+}
+
+static endAdminResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+
+unpack(): AdminResponseT {
+  return new AdminResponseT(
+    (this.message() !== null ? this.message()!.unpack() : null),
+    (this.receipt() !== null ? this.receipt()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: AdminResponseT): void {
+  _o.message = (this.message() !== null ? this.message()!.unpack() : null);
+  _o.receipt = (this.receipt() !== null ? this.receipt()!.unpack() : null);
+}
+}
+
+export class AdminResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public message: MailMessageT|null = null,
+  public receipt: MailBroadcastReceiptT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const message = (this.message !== null ? this.message!.pack(builder) : 0);
+  const receipt = (this.receipt !== null ? this.receipt!.pack(builder) : 0);
+
+  AdminResponse.startAdminResponse(builder);
+  AdminResponse.addMessage(builder, message);
+  AdminResponse.addReceipt(builder, receipt);
+
+  return AdminResponse.endAdminResponse(builder);
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/broadcast-request.ts

@@ -0,0 +1,111 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class BroadcastRequest implements flatbuffers.IUnpackableObject<BroadcastRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):BroadcastRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsBroadcastRequest(bb:flatbuffers.ByteBuffer, obj?:BroadcastRequest):BroadcastRequest {
+  return (obj || new BroadcastRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsBroadcastRequest(bb:flatbuffers.ByteBuffer, obj?:BroadcastRequest):BroadcastRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new BroadcastRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+subject():string|null
+subject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+subject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+body():string|null
+body(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+body(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+static startBroadcastRequest(builder:flatbuffers.Builder) {
+  builder.startObject(3);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addSubject(builder:flatbuffers.Builder, subjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, subjectOffset, 0);
+}
+
+static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, bodyOffset, 0);
+}
+
+static endBroadcastRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  return offset;
+}
+
+static createBroadcastRequest(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset, subjectOffset:flatbuffers.Offset, bodyOffset:flatbuffers.Offset):flatbuffers.Offset {
+  BroadcastRequest.startBroadcastRequest(builder);
+  BroadcastRequest.addGameId(builder, gameIdOffset);
+  BroadcastRequest.addSubject(builder, subjectOffset);
+  BroadcastRequest.addBody(builder, bodyOffset);
+  return BroadcastRequest.endBroadcastRequest(builder);
+}
+
+unpack(): BroadcastRequestT {
+  return new BroadcastRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    this.subject(),
+    this.body()
+  );
+}
+
+
+unpackTo(_o: BroadcastRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.subject = this.subject();
+  _o.body = this.body();
+}
+}
+
+export class BroadcastRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public subject: string|Uint8Array|null = null,
+  public body: string|Uint8Array|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const subject = (this.subject !== null ? builder.createString(this.subject!) : 0);
+  const body = (this.body !== null ? builder.createString(this.body!) : 0);
+
+  return BroadcastRequest.createBroadcastRequest(builder,
+    (this.gameId !== null ? this.gameId!.pack(builder) : 0),
+    subject,
+    body
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/broadcast-response.ts

@@ -0,0 +1,77 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailBroadcastReceipt, MailBroadcastReceiptT } from '../diplomail/mail-broadcast-receipt.js';
+
+
+export class BroadcastResponse implements flatbuffers.IUnpackableObject<BroadcastResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):BroadcastResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsBroadcastResponse(bb:flatbuffers.ByteBuffer, obj?:BroadcastResponse):BroadcastResponse {
+  return (obj || new BroadcastResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsBroadcastResponse(bb:flatbuffers.ByteBuffer, obj?:BroadcastResponse):BroadcastResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new BroadcastResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+receipt(obj?:MailBroadcastReceipt):MailBroadcastReceipt|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailBroadcastReceipt()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startBroadcastResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addReceipt(builder:flatbuffers.Builder, receiptOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, receiptOffset, 0);
+}
+
+static endBroadcastResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createBroadcastResponse(builder:flatbuffers.Builder, receiptOffset:flatbuffers.Offset):flatbuffers.Offset {
+  BroadcastResponse.startBroadcastResponse(builder);
+  BroadcastResponse.addReceipt(builder, receiptOffset);
+  return BroadcastResponse.endBroadcastResponse(builder);
+}
+
+unpack(): BroadcastResponseT {
+  return new BroadcastResponseT(
+    (this.receipt() !== null ? this.receipt()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: BroadcastResponseT): void {
+  _o.receipt = (this.receipt() !== null ? this.receipt()!.unpack() : null);
+}
+}
+
+export class BroadcastResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public receipt: MailBroadcastReceiptT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const receipt = (this.receipt !== null ? this.receipt!.pack(builder) : 0);
+
+  return BroadcastResponse.createBroadcastResponse(builder,
+    receipt
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/delete-request.ts

@@ -0,0 +1,86 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class DeleteRequest implements flatbuffers.IUnpackableObject<DeleteRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):DeleteRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsDeleteRequest(bb:flatbuffers.ByteBuffer, obj?:DeleteRequest):DeleteRequest {
+  return (obj || new DeleteRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsDeleteRequest(bb:flatbuffers.ByteBuffer, obj?:DeleteRequest):DeleteRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new DeleteRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+messageId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+static startDeleteRequest(builder:flatbuffers.Builder) {
+  builder.startObject(2);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(1, messageIdOffset, 0);
+}
+
+static endDeleteRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  builder.requiredField(offset, 6) // message_id
+  return offset;
+}
+
+
+unpack(): DeleteRequestT {
+  return new DeleteRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    (this.messageId() !== null ? this.messageId()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: DeleteRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.messageId = (this.messageId() !== null ? this.messageId()!.unpack() : null);
+}
+}
+
+export class DeleteRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public messageId: UUIDT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  DeleteRequest.startDeleteRequest(builder);
+  DeleteRequest.addGameId(builder, (this.gameId !== null ? this.gameId!.pack(builder) : 0));
+  DeleteRequest.addMessageId(builder, (this.messageId !== null ? this.messageId!.pack(builder) : 0));
+
+  return DeleteRequest.endDeleteRequest(builder);
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/delete-response.ts

@@ -0,0 +1,77 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailRecipientState, MailRecipientStateT } from '../diplomail/mail-recipient-state.js';
+
+
+export class DeleteResponse implements flatbuffers.IUnpackableObject<DeleteResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):DeleteResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsDeleteResponse(bb:flatbuffers.ByteBuffer, obj?:DeleteResponse):DeleteResponse {
+  return (obj || new DeleteResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsDeleteResponse(bb:flatbuffers.ByteBuffer, obj?:DeleteResponse):DeleteResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new DeleteResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+state(obj?:MailRecipientState):MailRecipientState|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailRecipientState()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startDeleteResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addState(builder:flatbuffers.Builder, stateOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, stateOffset, 0);
+}
+
+static endDeleteResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createDeleteResponse(builder:flatbuffers.Builder, stateOffset:flatbuffers.Offset):flatbuffers.Offset {
+  DeleteResponse.startDeleteResponse(builder);
+  DeleteResponse.addState(builder, stateOffset);
+  return DeleteResponse.endDeleteResponse(builder);
+}
+
+unpack(): DeleteResponseT {
+  return new DeleteResponseT(
+    (this.state() !== null ? this.state()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: DeleteResponseT): void {
+  _o.state = (this.state() !== null ? this.state()!.unpack() : null);
+}
+}
+
+export class DeleteResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public state: MailRecipientStateT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const state = (this.state !== null ? this.state!.pack(builder) : 0);
+
+  return DeleteResponse.createDeleteResponse(builder,
+    state
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/inbox-request.ts

@@ -0,0 +1,76 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class InboxRequest implements flatbuffers.IUnpackableObject<InboxRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):InboxRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsInboxRequest(bb:flatbuffers.ByteBuffer, obj?:InboxRequest):InboxRequest {
+  return (obj || new InboxRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsInboxRequest(bb:flatbuffers.ByteBuffer, obj?:InboxRequest):InboxRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new InboxRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+static startInboxRequest(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static endInboxRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  return offset;
+}
+
+static createInboxRequest(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset):flatbuffers.Offset {
+  InboxRequest.startInboxRequest(builder);
+  InboxRequest.addGameId(builder, gameIdOffset);
+  return InboxRequest.endInboxRequest(builder);
+}
+
+unpack(): InboxRequestT {
+  return new InboxRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: InboxRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+}
+}
+
+export class InboxRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  return InboxRequest.createInboxRequest(builder,
+    (this.gameId !== null ? this.gameId!.pack(builder) : 0)
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/inbox-response.ts

@@ -0,0 +1,94 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailMessage, MailMessageT } from '../diplomail/mail-message.js';
+
+
+export class InboxResponse implements flatbuffers.IUnpackableObject<InboxResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):InboxResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsInboxResponse(bb:flatbuffers.ByteBuffer, obj?:InboxResponse):InboxResponse {
+  return (obj || new InboxResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsInboxResponse(bb:flatbuffers.ByteBuffer, obj?:InboxResponse):InboxResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new InboxResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+items(index: number, obj?:MailMessage):MailMessage|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailMessage()).__init(this.bb!.__indirect(this.bb!.__vector(this.bb_pos + offset) + index * 4), this.bb!) : null;
+}
+
+itemsLength():number {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
+}
+
+static startInboxResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addItems(builder:flatbuffers.Builder, itemsOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, itemsOffset, 0);
+}
+
+static createItemsVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
+static startItemsVector(builder:flatbuffers.Builder, numElems:number) {
+  builder.startVector(4, numElems, 4);
+}
+
+static endInboxResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createInboxResponse(builder:flatbuffers.Builder, itemsOffset:flatbuffers.Offset):flatbuffers.Offset {
+  InboxResponse.startInboxResponse(builder);
+  InboxResponse.addItems(builder, itemsOffset);
+  return InboxResponse.endInboxResponse(builder);
+}
+
+unpack(): InboxResponseT {
+  return new InboxResponseT(
+    this.bb!.createObjList<MailMessage, MailMessageT>(this.items.bind(this), this.itemsLength())
+  );
+}
+
+
+unpackTo(_o: InboxResponseT): void {
+  _o.items = this.bb!.createObjList<MailMessage, MailMessageT>(this.items.bind(this), this.itemsLength());
+}
+}
+
+export class InboxResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public items: (MailMessageT)[] = []
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const items = InboxResponse.createItemsVector(builder, builder.createObjectOffsetList(this.items));
+
+  return InboxResponse.createInboxResponse(builder,
+    items
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/mail-broadcast-receipt.ts

@@ -0,0 +1,242 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+
+
+export class MailBroadcastReceipt implements flatbuffers.IUnpackableObject<MailBroadcastReceiptT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):MailBroadcastReceipt {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsMailBroadcastReceipt(bb:flatbuffers.ByteBuffer, obj?:MailBroadcastReceipt):MailBroadcastReceipt {
+  return (obj || new MailBroadcastReceipt()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsMailBroadcastReceipt(bb:flatbuffers.ByteBuffer, obj?:MailBroadcastReceipt):MailBroadcastReceipt {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new MailBroadcastReceipt()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+messageId():string|null
+messageId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+messageId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+gameId():string|null
+gameId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+gameId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+gameName():string|null
+gameName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+gameName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+kind():string|null
+kind(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+kind(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 10);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+senderKind():string|null
+senderKind(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+senderKind(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 12);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+subject():string|null
+subject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+subject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 14);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+body():string|null
+body(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+body(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+bodyLang():string|null
+bodyLang(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+bodyLang(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 18);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+broadcastScope():string|null
+broadcastScope(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+broadcastScope(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+createdAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 22);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+recipientCount():number {
+  const offset = this.bb!.__offset(this.bb_pos, 24);
+  return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
+}
+
+static startMailBroadcastReceipt(builder:flatbuffers.Builder) {
+  builder.startObject(11);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageIdOffset, 0);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, gameIdOffset, 0);
+}
+
+static addGameName(builder:flatbuffers.Builder, gameNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, gameNameOffset, 0);
+}
+
+static addKind(builder:flatbuffers.Builder, kindOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(3, kindOffset, 0);
+}
+
+static addSenderKind(builder:flatbuffers.Builder, senderKindOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(4, senderKindOffset, 0);
+}
+
+static addSubject(builder:flatbuffers.Builder, subjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(5, subjectOffset, 0);
+}
+
+static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(6, bodyOffset, 0);
+}
+
+static addBodyLang(builder:flatbuffers.Builder, bodyLangOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(7, bodyLangOffset, 0);
+}
+
+static addBroadcastScope(builder:flatbuffers.Builder, broadcastScopeOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(8, broadcastScopeOffset, 0);
+}
+
+static addCreatedAtMs(builder:flatbuffers.Builder, createdAtMs:bigint) {
+  builder.addFieldInt64(9, createdAtMs, BigInt('0'));
+}
+
+static addRecipientCount(builder:flatbuffers.Builder, recipientCount:number) {
+  builder.addFieldInt32(10, recipientCount, 0);
+}
+
+static endMailBroadcastReceipt(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createMailBroadcastReceipt(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset, gameIdOffset:flatbuffers.Offset, gameNameOffset:flatbuffers.Offset, kindOffset:flatbuffers.Offset, senderKindOffset:flatbuffers.Offset, subjectOffset:flatbuffers.Offset, bodyOffset:flatbuffers.Offset, bodyLangOffset:flatbuffers.Offset, broadcastScopeOffset:flatbuffers.Offset, createdAtMs:bigint, recipientCount:number):flatbuffers.Offset {
+  MailBroadcastReceipt.startMailBroadcastReceipt(builder);
+  MailBroadcastReceipt.addMessageId(builder, messageIdOffset);
+  MailBroadcastReceipt.addGameId(builder, gameIdOffset);
+  MailBroadcastReceipt.addGameName(builder, gameNameOffset);
+  MailBroadcastReceipt.addKind(builder, kindOffset);
+  MailBroadcastReceipt.addSenderKind(builder, senderKindOffset);
+  MailBroadcastReceipt.addSubject(builder, subjectOffset);
+  MailBroadcastReceipt.addBody(builder, bodyOffset);
+  MailBroadcastReceipt.addBodyLang(builder, bodyLangOffset);
+  MailBroadcastReceipt.addBroadcastScope(builder, broadcastScopeOffset);
+  MailBroadcastReceipt.addCreatedAtMs(builder, createdAtMs);
+  MailBroadcastReceipt.addRecipientCount(builder, recipientCount);
+  return MailBroadcastReceipt.endMailBroadcastReceipt(builder);
+}
+
+unpack(): MailBroadcastReceiptT {
+  return new MailBroadcastReceiptT(
+    this.messageId(),
+    this.gameId(),
+    this.gameName(),
+    this.kind(),
+    this.senderKind(),
+    this.subject(),
+    this.body(),
+    this.bodyLang(),
+    this.broadcastScope(),
+    this.createdAtMs(),
+    this.recipientCount()
+  );
+}
+
+
+unpackTo(_o: MailBroadcastReceiptT): void {
+  _o.messageId = this.messageId();
+  _o.gameId = this.gameId();
+  _o.gameName = this.gameName();
+  _o.kind = this.kind();
+  _o.senderKind = this.senderKind();
+  _o.subject = this.subject();
+  _o.body = this.body();
+  _o.bodyLang = this.bodyLang();
+  _o.broadcastScope = this.broadcastScope();
+  _o.createdAtMs = this.createdAtMs();
+  _o.recipientCount = this.recipientCount();
+}
+}
+
+export class MailBroadcastReceiptT implements flatbuffers.IGeneratedObject {
+constructor(
+  public messageId: string|Uint8Array|null = null,
+  public gameId: string|Uint8Array|null = null,
+  public gameName: string|Uint8Array|null = null,
+  public kind: string|Uint8Array|null = null,
+  public senderKind: string|Uint8Array|null = null,
+  public subject: string|Uint8Array|null = null,
+  public body: string|Uint8Array|null = null,
+  public bodyLang: string|Uint8Array|null = null,
+  public broadcastScope: string|Uint8Array|null = null,
+  public createdAtMs: bigint = BigInt('0'),
+  public recipientCount: number = 0
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const messageId = (this.messageId !== null ? builder.createString(this.messageId!) : 0);
+  const gameId = (this.gameId !== null ? builder.createString(this.gameId!) : 0);
+  const gameName = (this.gameName !== null ? builder.createString(this.gameName!) : 0);
+  const kind = (this.kind !== null ? builder.createString(this.kind!) : 0);
+  const senderKind = (this.senderKind !== null ? builder.createString(this.senderKind!) : 0);
+  const subject = (this.subject !== null ? builder.createString(this.subject!) : 0);
+  const body = (this.body !== null ? builder.createString(this.body!) : 0);
+  const bodyLang = (this.bodyLang !== null ? builder.createString(this.bodyLang!) : 0);
+  const broadcastScope = (this.broadcastScope !== null ? builder.createString(this.broadcastScope!) : 0);
+
+  return MailBroadcastReceipt.createMailBroadcastReceipt(builder,
+    messageId,
+    gameId,
+    gameName,
+    kind,
+    senderKind,
+    subject,
+    body,
+    bodyLang,
+    broadcastScope,
+    this.createdAtMs,
+    this.recipientCount
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/mail-message.ts

@@ -0,0 +1,426 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+
+
+export class MailMessage implements flatbuffers.IUnpackableObject<MailMessageT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):MailMessage {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsMailMessage(bb:flatbuffers.ByteBuffer, obj?:MailMessage):MailMessage {
+  return (obj || new MailMessage()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsMailMessage(bb:flatbuffers.ByteBuffer, obj?:MailMessage):MailMessage {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new MailMessage()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+messageId():string|null
+messageId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+messageId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+gameId():string|null
+gameId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+gameId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+gameName():string|null
+gameName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+gameName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+kind():string|null
+kind(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+kind(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 10);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+senderKind():string|null
+senderKind(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+senderKind(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 12);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+senderUserId():string|null
+senderUserId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+senderUserId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 14);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+senderUsername():string|null
+senderUsername(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+senderUsername(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+senderRaceName():string|null
+senderRaceName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+senderRaceName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 18);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+subject():string|null
+subject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+subject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+body():string|null
+body(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+body(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 22);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+bodyLang():string|null
+bodyLang(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+bodyLang(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 24);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+broadcastScope():string|null
+broadcastScope(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+broadcastScope(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 26);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+createdAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 28);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+recipientUserId():string|null
+recipientUserId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientUserId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 30);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipientUserName():string|null
+recipientUserName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientUserName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 32);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipientRaceName():string|null
+recipientRaceName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientRaceName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 34);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+readAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 36);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+deletedAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 38);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+translatedSubject():string|null
+translatedSubject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+translatedSubject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 40);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+translatedBody():string|null
+translatedBody(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+translatedBody(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 42);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+translationLang():string|null
+translationLang(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+translationLang(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 44);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+translator():string|null
+translator(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+translator(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 46);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+static startMailMessage(builder:flatbuffers.Builder) {
+  builder.startObject(22);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageIdOffset, 0);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, gameIdOffset, 0);
+}
+
+static addGameName(builder:flatbuffers.Builder, gameNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, gameNameOffset, 0);
+}
+
+static addKind(builder:flatbuffers.Builder, kindOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(3, kindOffset, 0);
+}
+
+static addSenderKind(builder:flatbuffers.Builder, senderKindOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(4, senderKindOffset, 0);
+}
+
+static addSenderUserId(builder:flatbuffers.Builder, senderUserIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(5, senderUserIdOffset, 0);
+}
+
+static addSenderUsername(builder:flatbuffers.Builder, senderUsernameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(6, senderUsernameOffset, 0);
+}
+
+static addSenderRaceName(builder:flatbuffers.Builder, senderRaceNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(7, senderRaceNameOffset, 0);
+}
+
+static addSubject(builder:flatbuffers.Builder, subjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(8, subjectOffset, 0);
+}
+
+static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(9, bodyOffset, 0);
+}
+
+static addBodyLang(builder:flatbuffers.Builder, bodyLangOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(10, bodyLangOffset, 0);
+}
+
+static addBroadcastScope(builder:flatbuffers.Builder, broadcastScopeOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(11, broadcastScopeOffset, 0);
+}
+
+static addCreatedAtMs(builder:flatbuffers.Builder, createdAtMs:bigint) {
+  builder.addFieldInt64(12, createdAtMs, BigInt('0'));
+}
+
+static addRecipientUserId(builder:flatbuffers.Builder, recipientUserIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(13, recipientUserIdOffset, 0);
+}
+
+static addRecipientUserName(builder:flatbuffers.Builder, recipientUserNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(14, recipientUserNameOffset, 0);
+}
+
+static addRecipientRaceName(builder:flatbuffers.Builder, recipientRaceNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(15, recipientRaceNameOffset, 0);
+}
+
+static addReadAtMs(builder:flatbuffers.Builder, readAtMs:bigint) {
+  builder.addFieldInt64(16, readAtMs, BigInt('0'));
+}
+
+static addDeletedAtMs(builder:flatbuffers.Builder, deletedAtMs:bigint) {
+  builder.addFieldInt64(17, deletedAtMs, BigInt('0'));
+}
+
+static addTranslatedSubject(builder:flatbuffers.Builder, translatedSubjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(18, translatedSubjectOffset, 0);
+}
+
+static addTranslatedBody(builder:flatbuffers.Builder, translatedBodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(19, translatedBodyOffset, 0);
+}
+
+static addTranslationLang(builder:flatbuffers.Builder, translationLangOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(20, translationLangOffset, 0);
+}
+
+static addTranslator(builder:flatbuffers.Builder, translatorOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(21, translatorOffset, 0);
+}
+
+static endMailMessage(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createMailMessage(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset, gameIdOffset:flatbuffers.Offset, gameNameOffset:flatbuffers.Offset, kindOffset:flatbuffers.Offset, senderKindOffset:flatbuffers.Offset, senderUserIdOffset:flatbuffers.Offset, senderUsernameOffset:flatbuffers.Offset, senderRaceNameOffset:flatbuffers.Offset, subjectOffset:flatbuffers.Offset, bodyOffset:flatbuffers.Offset, bodyLangOffset:flatbuffers.Offset, broadcastScopeOffset:flatbuffers.Offset, createdAtMs:bigint, recipientUserIdOffset:flatbuffers.Offset, recipientUserNameOffset:flatbuffers.Offset, recipientRaceNameOffset:flatbuffers.Offset, readAtMs:bigint, deletedAtMs:bigint, translatedSubjectOffset:flatbuffers.Offset, translatedBodyOffset:flatbuffers.Offset, translationLangOffset:flatbuffers.Offset, translatorOffset:flatbuffers.Offset):flatbuffers.Offset {
+  MailMessage.startMailMessage(builder);
+  MailMessage.addMessageId(builder, messageIdOffset);
+  MailMessage.addGameId(builder, gameIdOffset);
+  MailMessage.addGameName(builder, gameNameOffset);
+  MailMessage.addKind(builder, kindOffset);
+  MailMessage.addSenderKind(builder, senderKindOffset);
+  MailMessage.addSenderUserId(builder, senderUserIdOffset);
+  MailMessage.addSenderUsername(builder, senderUsernameOffset);
+  MailMessage.addSenderRaceName(builder, senderRaceNameOffset);
+  MailMessage.addSubject(builder, subjectOffset);
+  MailMessage.addBody(builder, bodyOffset);
+  MailMessage.addBodyLang(builder, bodyLangOffset);
+  MailMessage.addBroadcastScope(builder, broadcastScopeOffset);
+  MailMessage.addCreatedAtMs(builder, createdAtMs);
+  MailMessage.addRecipientUserId(builder, recipientUserIdOffset);
+  MailMessage.addRecipientUserName(builder, recipientUserNameOffset);
+  MailMessage.addRecipientRaceName(builder, recipientRaceNameOffset);
+  MailMessage.addReadAtMs(builder, readAtMs);
+  MailMessage.addDeletedAtMs(builder, deletedAtMs);
+  MailMessage.addTranslatedSubject(builder, translatedSubjectOffset);
+  MailMessage.addTranslatedBody(builder, translatedBodyOffset);
+  MailMessage.addTranslationLang(builder, translationLangOffset);
+  MailMessage.addTranslator(builder, translatorOffset);
+  return MailMessage.endMailMessage(builder);
+}
+
+unpack(): MailMessageT {
+  return new MailMessageT(
+    this.messageId(),
+    this.gameId(),
+    this.gameName(),
+    this.kind(),
+    this.senderKind(),
+    this.senderUserId(),
+    this.senderUsername(),
+    this.senderRaceName(),
+    this.subject(),
+    this.body(),
+    this.bodyLang(),
+    this.broadcastScope(),
+    this.createdAtMs(),
+    this.recipientUserId(),
+    this.recipientUserName(),
+    this.recipientRaceName(),
+    this.readAtMs(),
+    this.deletedAtMs(),
+    this.translatedSubject(),
+    this.translatedBody(),
+    this.translationLang(),
+    this.translator()
+  );
+}
+
+
+unpackTo(_o: MailMessageT): void {
+  _o.messageId = this.messageId();
+  _o.gameId = this.gameId();
+  _o.gameName = this.gameName();
+  _o.kind = this.kind();
+  _o.senderKind = this.senderKind();
+  _o.senderUserId = this.senderUserId();
+  _o.senderUsername = this.senderUsername();
+  _o.senderRaceName = this.senderRaceName();
+  _o.subject = this.subject();
+  _o.body = this.body();
+  _o.bodyLang = this.bodyLang();
+  _o.broadcastScope = this.broadcastScope();
+  _o.createdAtMs = this.createdAtMs();
+  _o.recipientUserId = this.recipientUserId();
+  _o.recipientUserName = this.recipientUserName();
+  _o.recipientRaceName = this.recipientRaceName();
+  _o.readAtMs = this.readAtMs();
+  _o.deletedAtMs = this.deletedAtMs();
+  _o.translatedSubject = this.translatedSubject();
+  _o.translatedBody = this.translatedBody();
+  _o.translationLang = this.translationLang();
+  _o.translator = this.translator();
+}
+}
+
+export class MailMessageT implements flatbuffers.IGeneratedObject {
+constructor(
+  public messageId: string|Uint8Array|null = null,
+  public gameId: string|Uint8Array|null = null,
+  public gameName: string|Uint8Array|null = null,
+  public kind: string|Uint8Array|null = null,
+  public senderKind: string|Uint8Array|null = null,
+  public senderUserId: string|Uint8Array|null = null,
+  public senderUsername: string|Uint8Array|null = null,
+  public senderRaceName: string|Uint8Array|null = null,
+  public subject: string|Uint8Array|null = null,
+  public body: string|Uint8Array|null = null,
+  public bodyLang: string|Uint8Array|null = null,
+  public broadcastScope: string|Uint8Array|null = null,
+  public createdAtMs: bigint = BigInt('0'),
+  public recipientUserId: string|Uint8Array|null = null,
+  public recipientUserName: string|Uint8Array|null = null,
+  public recipientRaceName: string|Uint8Array|null = null,
+  public readAtMs: bigint = BigInt('0'),
+  public deletedAtMs: bigint = BigInt('0'),
+  public translatedSubject: string|Uint8Array|null = null,
+  public translatedBody: string|Uint8Array|null = null,
+  public translationLang: string|Uint8Array|null = null,
+  public translator: string|Uint8Array|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const messageId = (this.messageId !== null ? builder.createString(this.messageId!) : 0);
+  const gameId = (this.gameId !== null ? builder.createString(this.gameId!) : 0);
+  const gameName = (this.gameName !== null ? builder.createString(this.gameName!) : 0);
+  const kind = (this.kind !== null ? builder.createString(this.kind!) : 0);
+  const senderKind = (this.senderKind !== null ? builder.createString(this.senderKind!) : 0);
+  const senderUserId = (this.senderUserId !== null ? builder.createString(this.senderUserId!) : 0);
+  const senderUsername = (this.senderUsername !== null ? builder.createString(this.senderUsername!) : 0);
+  const senderRaceName = (this.senderRaceName !== null ? builder.createString(this.senderRaceName!) : 0);
+  const subject = (this.subject !== null ? builder.createString(this.subject!) : 0);
+  const body = (this.body !== null ? builder.createString(this.body!) : 0);
+  const bodyLang = (this.bodyLang !== null ? builder.createString(this.bodyLang!) : 0);
+  const broadcastScope = (this.broadcastScope !== null ? builder.createString(this.broadcastScope!) : 0);
+  const recipientUserId = (this.recipientUserId !== null ? builder.createString(this.recipientUserId!) : 0);
+  const recipientUserName = (this.recipientUserName !== null ? builder.createString(this.recipientUserName!) : 0);
+  const recipientRaceName = (this.recipientRaceName !== null ? builder.createString(this.recipientRaceName!) : 0);
+  const translatedSubject = (this.translatedSubject !== null ? builder.createString(this.translatedSubject!) : 0);
+  const translatedBody = (this.translatedBody !== null ? builder.createString(this.translatedBody!) : 0);
+  const translationLang = (this.translationLang !== null ? builder.createString(this.translationLang!) : 0);
+  const translator = (this.translator !== null ? builder.createString(this.translator!) : 0);
+
+  return MailMessage.createMailMessage(builder,
+    messageId,
+    gameId,
+    gameName,
+    kind,
+    senderKind,
+    senderUserId,
+    senderUsername,
+    senderRaceName,
+    subject,
+    body,
+    bodyLang,
+    broadcastScope,
+    this.createdAtMs,
+    recipientUserId,
+    recipientUserName,
+    recipientRaceName,
+    this.readAtMs,
+    this.deletedAtMs,
+    translatedSubject,
+    translatedBody,
+    translationLang,
+    translator
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/mail-recipient-state.ts

@@ -0,0 +1,106 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+
+
+export class MailRecipientState implements flatbuffers.IUnpackableObject<MailRecipientStateT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):MailRecipientState {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsMailRecipientState(bb:flatbuffers.ByteBuffer, obj?:MailRecipientState):MailRecipientState {
+  return (obj || new MailRecipientState()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsMailRecipientState(bb:flatbuffers.ByteBuffer, obj?:MailRecipientState):MailRecipientState {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new MailRecipientState()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+messageId():string|null
+messageId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+messageId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+readAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+deletedAtMs():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+static startMailRecipientState(builder:flatbuffers.Builder) {
+  builder.startObject(3);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageIdOffset, 0);
+}
+
+static addReadAtMs(builder:flatbuffers.Builder, readAtMs:bigint) {
+  builder.addFieldInt64(1, readAtMs, BigInt('0'));
+}
+
+static addDeletedAtMs(builder:flatbuffers.Builder, deletedAtMs:bigint) {
+  builder.addFieldInt64(2, deletedAtMs, BigInt('0'));
+}
+
+static endMailRecipientState(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createMailRecipientState(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset, readAtMs:bigint, deletedAtMs:bigint):flatbuffers.Offset {
+  MailRecipientState.startMailRecipientState(builder);
+  MailRecipientState.addMessageId(builder, messageIdOffset);
+  MailRecipientState.addReadAtMs(builder, readAtMs);
+  MailRecipientState.addDeletedAtMs(builder, deletedAtMs);
+  return MailRecipientState.endMailRecipientState(builder);
+}
+
+unpack(): MailRecipientStateT {
+  return new MailRecipientStateT(
+    this.messageId(),
+    this.readAtMs(),
+    this.deletedAtMs()
+  );
+}
+
+
+unpackTo(_o: MailRecipientStateT): void {
+  _o.messageId = this.messageId();
+  _o.readAtMs = this.readAtMs();
+  _o.deletedAtMs = this.deletedAtMs();
+}
+}
+
+export class MailRecipientStateT implements flatbuffers.IGeneratedObject {
+constructor(
+  public messageId: string|Uint8Array|null = null,
+  public readAtMs: bigint = BigInt('0'),
+  public deletedAtMs: bigint = BigInt('0')
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const messageId = (this.messageId !== null ? builder.createString(this.messageId!) : 0);
+
+  return MailRecipientState.createMailRecipientState(builder,
+    messageId,
+    this.readAtMs,
+    this.deletedAtMs
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/message-get-request.ts

@@ -0,0 +1,86 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class MessageGetRequest implements flatbuffers.IUnpackableObject<MessageGetRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):MessageGetRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsMessageGetRequest(bb:flatbuffers.ByteBuffer, obj?:MessageGetRequest):MessageGetRequest {
+  return (obj || new MessageGetRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsMessageGetRequest(bb:flatbuffers.ByteBuffer, obj?:MessageGetRequest):MessageGetRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new MessageGetRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+messageId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+static startMessageGetRequest(builder:flatbuffers.Builder) {
+  builder.startObject(2);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(1, messageIdOffset, 0);
+}
+
+static endMessageGetRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  builder.requiredField(offset, 6) // message_id
+  return offset;
+}
+
+
+unpack(): MessageGetRequestT {
+  return new MessageGetRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    (this.messageId() !== null ? this.messageId()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: MessageGetRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.messageId = (this.messageId() !== null ? this.messageId()!.unpack() : null);
+}
+}
+
+export class MessageGetRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public messageId: UUIDT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  MessageGetRequest.startMessageGetRequest(builder);
+  MessageGetRequest.addGameId(builder, (this.gameId !== null ? this.gameId!.pack(builder) : 0));
+  MessageGetRequest.addMessageId(builder, (this.messageId !== null ? this.messageId!.pack(builder) : 0));
+
+  return MessageGetRequest.endMessageGetRequest(builder);
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/message-get-response.ts

@@ -0,0 +1,77 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailMessage, MailMessageT } from '../diplomail/mail-message.js';
+
+
+export class MessageGetResponse implements flatbuffers.IUnpackableObject<MessageGetResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):MessageGetResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsMessageGetResponse(bb:flatbuffers.ByteBuffer, obj?:MessageGetResponse):MessageGetResponse {
+  return (obj || new MessageGetResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsMessageGetResponse(bb:flatbuffers.ByteBuffer, obj?:MessageGetResponse):MessageGetResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new MessageGetResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+message(obj?:MailMessage):MailMessage|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailMessage()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startMessageGetResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addMessage(builder:flatbuffers.Builder, messageOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageOffset, 0);
+}
+
+static endMessageGetResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createMessageGetResponse(builder:flatbuffers.Builder, messageOffset:flatbuffers.Offset):flatbuffers.Offset {
+  MessageGetResponse.startMessageGetResponse(builder);
+  MessageGetResponse.addMessage(builder, messageOffset);
+  return MessageGetResponse.endMessageGetResponse(builder);
+}
+
+unpack(): MessageGetResponseT {
+  return new MessageGetResponseT(
+    (this.message() !== null ? this.message()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: MessageGetResponseT): void {
+  _o.message = (this.message() !== null ? this.message()!.unpack() : null);
+}
+}
+
+export class MessageGetResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public message: MailMessageT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const message = (this.message !== null ? this.message!.pack(builder) : 0);
+
+  return MessageGetResponse.createMessageGetResponse(builder,
+    message
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/read-request.ts

@@ -0,0 +1,86 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class ReadRequest implements flatbuffers.IUnpackableObject<ReadRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):ReadRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsReadRequest(bb:flatbuffers.ByteBuffer, obj?:ReadRequest):ReadRequest {
+  return (obj || new ReadRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsReadRequest(bb:flatbuffers.ByteBuffer, obj?:ReadRequest):ReadRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new ReadRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+messageId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+static startReadRequest(builder:flatbuffers.Builder) {
+  builder.startObject(2);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addMessageId(builder:flatbuffers.Builder, messageIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(1, messageIdOffset, 0);
+}
+
+static endReadRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  builder.requiredField(offset, 6) // message_id
+  return offset;
+}
+
+
+unpack(): ReadRequestT {
+  return new ReadRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    (this.messageId() !== null ? this.messageId()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: ReadRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.messageId = (this.messageId() !== null ? this.messageId()!.unpack() : null);
+}
+}
+
+export class ReadRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public messageId: UUIDT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  ReadRequest.startReadRequest(builder);
+  ReadRequest.addGameId(builder, (this.gameId !== null ? this.gameId!.pack(builder) : 0));
+  ReadRequest.addMessageId(builder, (this.messageId !== null ? this.messageId!.pack(builder) : 0));
+
+  return ReadRequest.endReadRequest(builder);
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/read-response.ts

@@ -0,0 +1,77 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailRecipientState, MailRecipientStateT } from '../diplomail/mail-recipient-state.js';
+
+
+export class ReadResponse implements flatbuffers.IUnpackableObject<ReadResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):ReadResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsReadResponse(bb:flatbuffers.ByteBuffer, obj?:ReadResponse):ReadResponse {
+  return (obj || new ReadResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsReadResponse(bb:flatbuffers.ByteBuffer, obj?:ReadResponse):ReadResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new ReadResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+state(obj?:MailRecipientState):MailRecipientState|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailRecipientState()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startReadResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addState(builder:flatbuffers.Builder, stateOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, stateOffset, 0);
+}
+
+static endReadResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createReadResponse(builder:flatbuffers.Builder, stateOffset:flatbuffers.Offset):flatbuffers.Offset {
+  ReadResponse.startReadResponse(builder);
+  ReadResponse.addState(builder, stateOffset);
+  return ReadResponse.endReadResponse(builder);
+}
+
+unpack(): ReadResponseT {
+  return new ReadResponseT(
+    (this.state() !== null ? this.state()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: ReadResponseT): void {
+  _o.state = (this.state() !== null ? this.state()!.unpack() : null);
+}
+}
+
+export class ReadResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public state: MailRecipientStateT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const state = (this.state !== null ? this.state!.pack(builder) : 0);
+
+  return ReadResponse.createReadResponse(builder,
+    state
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/send-request.ts

@@ -0,0 +1,145 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class SendRequest implements flatbuffers.IUnpackableObject<SendRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):SendRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsSendRequest(bb:flatbuffers.ByteBuffer, obj?:SendRequest):SendRequest {
+  return (obj || new SendRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsSendRequest(bb:flatbuffers.ByteBuffer, obj?:SendRequest):SendRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new SendRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+recipientUserId():string|null
+recipientUserId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientUserId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+recipientRaceName():string|null
+recipientRaceName(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+recipientRaceName(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+subject():string|null
+subject(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+subject(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 10);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+body():string|null
+body(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+body(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 12);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+static startSendRequest(builder:flatbuffers.Builder) {
+  builder.startObject(5);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static addRecipientUserId(builder:flatbuffers.Builder, recipientUserIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, recipientUserIdOffset, 0);
+}
+
+static addRecipientRaceName(builder:flatbuffers.Builder, recipientRaceNameOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, recipientRaceNameOffset, 0);
+}
+
+static addSubject(builder:flatbuffers.Builder, subjectOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(3, subjectOffset, 0);
+}
+
+static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(4, bodyOffset, 0);
+}
+
+static endSendRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  return offset;
+}
+
+static createSendRequest(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset, recipientUserIdOffset:flatbuffers.Offset, recipientRaceNameOffset:flatbuffers.Offset, subjectOffset:flatbuffers.Offset, bodyOffset:flatbuffers.Offset):flatbuffers.Offset {
+  SendRequest.startSendRequest(builder);
+  SendRequest.addGameId(builder, gameIdOffset);
+  SendRequest.addRecipientUserId(builder, recipientUserIdOffset);
+  SendRequest.addRecipientRaceName(builder, recipientRaceNameOffset);
+  SendRequest.addSubject(builder, subjectOffset);
+  SendRequest.addBody(builder, bodyOffset);
+  return SendRequest.endSendRequest(builder);
+}
+
+unpack(): SendRequestT {
+  return new SendRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null),
+    this.recipientUserId(),
+    this.recipientRaceName(),
+    this.subject(),
+    this.body()
+  );
+}
+
+
+unpackTo(_o: SendRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+  _o.recipientUserId = this.recipientUserId();
+  _o.recipientRaceName = this.recipientRaceName();
+  _o.subject = this.subject();
+  _o.body = this.body();
+}
+}
+
+export class SendRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null,
+  public recipientUserId: string|Uint8Array|null = null,
+  public recipientRaceName: string|Uint8Array|null = null,
+  public subject: string|Uint8Array|null = null,
+  public body: string|Uint8Array|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const recipientUserId = (this.recipientUserId !== null ? builder.createString(this.recipientUserId!) : 0);
+  const recipientRaceName = (this.recipientRaceName !== null ? builder.createString(this.recipientRaceName!) : 0);
+  const subject = (this.subject !== null ? builder.createString(this.subject!) : 0);
+  const body = (this.body !== null ? builder.createString(this.body!) : 0);
+
+  return SendRequest.createSendRequest(builder,
+    (this.gameId !== null ? this.gameId!.pack(builder) : 0),
+    recipientUserId,
+    recipientRaceName,
+    subject,
+    body
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/send-response.ts

@@ -0,0 +1,77 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailMessage, MailMessageT } from '../diplomail/mail-message.js';
+
+
+export class SendResponse implements flatbuffers.IUnpackableObject<SendResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):SendResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsSendResponse(bb:flatbuffers.ByteBuffer, obj?:SendResponse):SendResponse {
+  return (obj || new SendResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsSendResponse(bb:flatbuffers.ByteBuffer, obj?:SendResponse):SendResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new SendResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+message(obj?:MailMessage):MailMessage|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailMessage()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static startSendResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addMessage(builder:flatbuffers.Builder, messageOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, messageOffset, 0);
+}
+
+static endSendResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createSendResponse(builder:flatbuffers.Builder, messageOffset:flatbuffers.Offset):flatbuffers.Offset {
+  SendResponse.startSendResponse(builder);
+  SendResponse.addMessage(builder, messageOffset);
+  return SendResponse.endSendResponse(builder);
+}
+
+unpack(): SendResponseT {
+  return new SendResponseT(
+    (this.message() !== null ? this.message()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: SendResponseT): void {
+  _o.message = (this.message() !== null ? this.message()!.unpack() : null);
+}
+}
+
+export class SendResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public message: MailMessageT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const message = (this.message !== null ? this.message!.pack(builder) : 0);
+
+  return SendResponse.createSendResponse(builder,
+    message
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/sent-request.ts

@@ -0,0 +1,76 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class SentRequest implements flatbuffers.IUnpackableObject<SentRequestT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):SentRequest {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsSentRequest(bb:flatbuffers.ByteBuffer, obj?:SentRequest):SentRequest {
+  return (obj || new SentRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsSentRequest(bb:flatbuffers.ByteBuffer, obj?:SentRequest):SentRequest {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new SentRequest()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+gameId(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+static startSentRequest(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, gameIdOffset, 0);
+}
+
+static endSentRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // game_id
+  return offset;
+}
+
+static createSentRequest(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset):flatbuffers.Offset {
+  SentRequest.startSentRequest(builder);
+  SentRequest.addGameId(builder, gameIdOffset);
+  return SentRequest.endSentRequest(builder);
+}
+
+unpack(): SentRequestT {
+  return new SentRequestT(
+    (this.gameId() !== null ? this.gameId()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: SentRequestT): void {
+  _o.gameId = (this.gameId() !== null ? this.gameId()!.unpack() : null);
+}
+}
+
+export class SentRequestT implements flatbuffers.IGeneratedObject {
+constructor(
+  public gameId: UUIDT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  return SentRequest.createSentRequest(builder,
+    (this.gameId !== null ? this.gameId!.pack(builder) : 0)
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/diplomail/sent-response.ts

@@ -0,0 +1,94 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { MailMessage, MailMessageT } from '../diplomail/mail-message.js';
+
+
+export class SentResponse implements flatbuffers.IUnpackableObject<SentResponseT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):SentResponse {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsSentResponse(bb:flatbuffers.ByteBuffer, obj?:SentResponse):SentResponse {
+  return (obj || new SentResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsSentResponse(bb:flatbuffers.ByteBuffer, obj?:SentResponse):SentResponse {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new SentResponse()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+items(index: number, obj?:MailMessage):MailMessage|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new MailMessage()).__init(this.bb!.__indirect(this.bb!.__vector(this.bb_pos + offset) + index * 4), this.bb!) : null;
+}
+
+itemsLength():number {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
+}
+
+static startSentResponse(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addItems(builder:flatbuffers.Builder, itemsOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, itemsOffset, 0);
+}
+
+static createItemsVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
+static startItemsVector(builder:flatbuffers.Builder, numElems:number) {
+  builder.startVector(4, numElems, 4);
+}
+
+static endSentResponse(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createSentResponse(builder:flatbuffers.Builder, itemsOffset:flatbuffers.Offset):flatbuffers.Offset {
+  SentResponse.startSentResponse(builder);
+  SentResponse.addItems(builder, itemsOffset);
+  return SentResponse.endSentResponse(builder);
+}
+
+unpack(): SentResponseT {
+  return new SentResponseT(
+    this.bb!.createObjList<MailMessage, MailMessageT>(this.items.bind(this), this.itemsLength())
+  );
+}
+
+
+unpackTo(_o: SentResponseT): void {
+  _o.items = this.bb!.createObjList<MailMessage, MailMessageT>(this.items.bind(this), this.itemsLength());
+}
+}
+
+export class SentResponseT implements flatbuffers.IGeneratedObject {
+constructor(
+  public items: (MailMessageT)[] = []
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const items = SentResponse.createItemsVector(builder, builder.createObjectOffsetList(this.items));
+
+  return SentResponse.createSentResponse(builder,
+    items
+  );
+}
+}

ui/frontend/src/routes/games/[id]/+layout.svelte

@@ -96,6 +96,7 @@ fresh.
 		type VerifiedEvent,
 	} from "../../../api/events.svelte";
 	import { toast } from "$lib/toast.svelte";
+	import { mailStore } from "$lib/mail-store.svelte";
 
 	let { children } = $props();
 
@@ -241,6 +242,7 @@ fresh.
 	// `currentTurn` is known cannot misfire.
 	let unsubTurnReady: (() => void) | null = null;
 	let unsubGamePaused: (() => void) | null = null;
+	let unsubMailReceived: (() => void) | null = null;
 	const turnReadyDecoder = new TextDecoder("utf-8");
 
 	function parseTurnReadyPayload(
@@ -268,6 +270,32 @@ fresh.
 		}
 	}
 
+	function parseMailReceivedPayload(
+		event: VerifiedEvent,
+	): { gameId: string; from: string } | null {
+		try {
+			const text = turnReadyDecoder.decode(event.payloadBytes);
+			const json: unknown = JSON.parse(text);
+			if (typeof json !== "object" || json === null) {
+				return null;
+			}
+			const record = json as Record<string, unknown>;
+			const eventGameId = record.game_id;
+			if (typeof eventGameId !== "string") {
+				return null;
+			}
+			const subject =
+				typeof record.subject === "string" && record.subject !== ""
+					? record.subject
+					: typeof record.preview === "string"
+						? record.preview
+						: "";
+			return { gameId: eventGameId, from: subject };
+		} catch {
+			return null;
+		}
+	}
+
 	function parseGamePausedPayload(
 		event: VerifiedEvent,
 	): { gameId: string; reason: string } | null {
@@ -408,9 +436,29 @@ fresh.
 					}
 					orderDraft.markPaused({ reason: parsed.reason });
 				});
+				unsubMailReceived = eventStream.on(
+					"diplomail.message.received",
+					(event) => {
+						const parsed = parseMailReceivedPayload(event);
+						if (parsed === null || parsed.gameId !== gameId) {
+							return;
+						}
+						void mailStore.applyPushEvent(parsed.gameId);
+						toast.show({
+							messageKey: "game.events.mail_new.message",
+							messageParams: { from: parsed.from },
+							actionLabelKey: "game.events.mail_new.action",
+							onAction: () => {
+								void goto(`/games/${gameId}/mail`);
+							},
+							durationMs: 8000,
+						});
+					},
+				);
 				await Promise.all([
 					gameState.init({ client, cache, gameId }),
 					orderDraft.init({ cache, gameId }),
+					mailStore.init({ client, cache, gameId }),
 				]);
 				galaxyClient.set(client);
 				orderDraft.bindClient(client, {
@@ -442,6 +490,10 @@ fresh.
 			unsubGamePaused();
 			unsubGamePaused = null;
 		}
+		if (unsubMailReceived !== null) {
+			unsubMailReceived();
+			unsubMailReceived = null;
+		}
 		gameState.dispose();
 		orderDraft.dispose();
 		selection.dispose();

ui/frontend/tests/mail-store.test.ts

@@ -0,0 +1,125 @@
+// Phase 28 — MailStore threading projection tests. Exercises the
+// `entries` derived rune end-to-end with handcrafted inbox + sent
+// fixtures; the network surface (GalaxyClient) is left null since
+// these tests do not call init / setGame.
+
+import { describe, expect, it } from "vitest";
+
+import {
+	MailStore,
+	type MailListEntry,
+	type MailStandalone,
+	type MailThread,
+} from "../src/lib/mail-store.svelte";
+import type { MailMessage } from "../src/api/diplomail";
+
+function makeMessage(overrides: Partial<MailMessage>): MailMessage {
+	return {
+		messageId: overrides.messageId ?? crypto.randomUUID(),
+		gameId: overrides.gameId ?? "00000000-0000-0000-0000-000000000001",
+		gameName: overrides.gameName ?? "Test game",
+		kind: overrides.kind ?? "personal",
+		senderKind: overrides.senderKind ?? "player",
+		senderUserId: overrides.senderUserId ?? null,
+		senderUsername: overrides.senderUsername ?? null,
+		senderRaceName: overrides.senderRaceName ?? null,
+		subject: overrides.subject ?? "",
+		body: overrides.body ?? "",
+		bodyLang: overrides.bodyLang ?? "en",
+		broadcastScope: overrides.broadcastScope ?? "single",
+		createdAt: overrides.createdAt ?? new Date(0),
+		recipientUserId:
+			overrides.recipientUserId ?? "00000000-0000-0000-0000-000000000099",
+		recipientUserName: overrides.recipientUserName ?? "self",
+		recipientRaceName: overrides.recipientRaceName ?? null,
+		readAt: overrides.readAt ?? null,
+		deletedAt: overrides.deletedAt ?? null,
+		translatedSubject: overrides.translatedSubject ?? null,
+		translatedBody: overrides.translatedBody ?? null,
+		translationLang: overrides.translationLang ?? null,
+		translator: overrides.translator ?? null,
+	};
+}
+
+describe("MailStore.entries", () => {
+	it("groups inbox + sent messages into per-race threads", () => {
+		const store = new MailStore();
+		const greysIncoming = makeMessage({
+			messageId: "m1",
+			senderKind: "player",
+			senderRaceName: "Greys",
+			body: "hi",
+			createdAt: new Date("2026-05-15T12:00:00Z"),
+		});
+		const greysOutgoing = makeMessage({
+			messageId: "m2",
+			senderKind: "player",
+			senderRaceName: "Self",
+			recipientRaceName: "Greys",
+			body: "reply",
+			createdAt: new Date("2026-05-15T12:05:00Z"),
+		});
+		store.inbox = [greysIncoming];
+		store.sent = [greysOutgoing];
+
+		const entries = store.entries;
+		expect(entries.length).toBe(1);
+		const entry = entries[0];
+		expect(entry.kind).toBe("thread");
+		const thread = entry as MailThread;
+		expect(thread.raceName).toBe("Greys");
+		expect(thread.messages.map((m) => m.messageId)).toEqual(["m1", "m2"]);
+	});
+
+	it("surfaces system and admin messages as stand-alone items", () => {
+		const store = new MailStore();
+		const system = makeMessage({
+			messageId: "sys-1",
+			kind: "admin",
+			senderKind: "system",
+			subject: "game.paused: details",
+			createdAt: new Date("2026-05-15T13:00:00Z"),
+		});
+		const admin = makeMessage({
+			messageId: "adm-1",
+			kind: "admin",
+			senderKind: "admin",
+			createdAt: new Date("2026-05-15T13:05:00Z"),
+		});
+		store.inbox = [system, admin];
+
+		const entries: MailListEntry[] = store.entries;
+		expect(entries.every((e) => e.kind === "standalone")).toBe(true);
+		const standalones = entries as MailStandalone[];
+		expect(standalones.map((e) => e.message.messageId).sort()).toEqual(
+			["adm-1", "sys-1"],
+		);
+	});
+
+	it("treats the local player's broadcasts as stand-alone outgoing", () => {
+		const store = new MailStore();
+		const broadcast = makeMessage({
+			messageId: "br-1",
+			senderKind: "player",
+			senderRaceName: "Self",
+			recipientRaceName: "Greys",
+			broadcastScope: "game_broadcast",
+			createdAt: new Date("2026-05-15T14:00:00Z"),
+		});
+		store.sent = [broadcast];
+
+		const entries = store.entries;
+		expect(entries.length).toBe(1);
+		expect(entries[0].kind).toBe("standalone");
+	});
+
+	it("counts unread incoming messages in unreadCount", () => {
+		const store = new MailStore();
+		store.inbox = [
+			makeMessage({ readAt: null, createdAt: new Date(1) }),
+			makeMessage({ readAt: new Date(2), createdAt: new Date(2) }),
+			makeMessage({ readAt: null, createdAt: new Date(3) }),
+		];
+		expect(store.unreadCount).toBe(2);
+	});
+});