diff --git a/backend/internal/account/account.go b/backend/internal/account/account.go
index e4826d5..1dcb901 100644
--- a/backend/internal/account/account.go
+++ b/backend/internal/account/account.go
@@ -71,6 +71,11 @@ type Account struct {
 	// uuid.Nil for a live account. A tombstone keeps the row so the no-cascade
 	// foreign keys of a shared finished game stay valid.
 	MergedInto uuid.UUID
+	// Deleted marks a tombstoned account (accounts.deleted_at set): its credentials are
+	// journalled and freed and its live surfaces anonymised, but the row survives for the
+	// no-cascade foreign keys. Nobody is behind it any more, so it takes part in no social
+	// exchange (docs/ARCHITECTURE.md §9.1).
+	Deleted bool
 	// FlaggedHighRateAt is the soft, reversible "suspected high-rate" marker: the
 	// zero time for an unflagged account, otherwise when the gateway-reported
 	// rate-limiter rejections first crossed the sustained threshold. An
@@ -630,6 +635,7 @@ func modelToAccount(row model.Accounts) Account {
 		IsGuest:                row.IsGuest,
 		NotificationsInAppOnly: row.NotificationsInAppOnly,
 		MergedInto:             mergedInto,
+		Deleted:                row.DeletedAt != nil,
 		FlaggedHighRateAt:      flaggedHighRateAt,
 		CreatedAt:              row.CreatedAt,
 		UpdatedAt:              row.UpdatedAt,
diff --git a/backend/internal/account/retention.go b/backend/internal/account/retention.go
index b6f161e..e57cbe9 100644
--- a/backend/internal/account/retention.go
+++ b/backend/internal/account/retention.go
@@ -180,6 +180,32 @@ func (s *Store) DeletionInfo(ctx context.Context, accountID uuid.UUID) (Deletion
 	return info, nil
 }
 
+// DeletedIDs returns the subset of ids whose accounts are tombstoned (deleted_at set), as a
+// set. It is the batch form of Account.Deleted for a caller holding several ids at once —
+// the game views resolve every seat's deleted mark in one round-trip. An empty ids slice
+// queries nothing and returns an empty set; an unknown id is simply absent from the result.
+func (s *Store) DeletedIDs(ctx context.Context, ids []uuid.UUID) (map[uuid.UUID]bool, error) {
+	out := map[uuid.UUID]bool{}
+	if len(ids) == 0 {
+		return out, nil
+	}
+	exprs := make([]postgres.Expression, len(ids))
+	for i, id := range ids {
+		exprs[i] = postgres.UUID(id)
+	}
+	stmt := postgres.SELECT(table.Accounts.AccountID).
+		FROM(table.Accounts).
+		WHERE(table.Accounts.AccountID.IN(exprs...).AND(table.Accounts.DeletedAt.IS_NOT_NULL()))
+	var rows []model.Accounts
+	if err := stmt.QueryContext(ctx, s.db, &rows); err != nil {
+		return nil, fmt.Errorf("account: deleted ids: %w", err)
+	}
+	for _, r := range rows {
+		out[r.AccountID] = true
+	}
+	return out, nil
+}
+
 // RetentionReaper periodically purges expired account-deletion retention data via
 // Store.ReapExpiredRetention, mirroring GuestReaper: one background goroutine started once
 // from main.
diff --git a/backend/internal/inttest/delete_test.go b/backend/internal/inttest/delete_test.go
index 984321c..6e7e6a2 100644
--- a/backend/internal/inttest/delete_test.go
+++ b/backend/internal/inttest/delete_test.go
@@ -5,17 +5,22 @@ package inttest
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
 	"errors"
+	"net/http"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/google/uuid"
+	"go.uber.org/zap/zaptest"
 
 	"scrabble/backend/internal/account"
 	"scrabble/backend/internal/accountdelete"
 	"scrabble/backend/internal/engine"
 	"scrabble/backend/internal/game"
+	"scrabble/backend/internal/server"
+	"scrabble/backend/internal/social"
 )
 
 // deletedFields reads a tombstoned account's retained real name and its deleted_at.
@@ -277,6 +282,115 @@ func TestDropAllRobotGames(t *testing.T) {
 	}
 }
 
+// TestDeletedAccountRefusesSocialActions: once an opponent's account is deleted, neither a
+// friend request nor a block may target it — the client hides both controls on a deleted
+// seat, and the server refuses them for an older client. The seat's deleted mark that drives
+// that hiding is resolved by Store.DeletedIDs.
+func TestDeletedAccountRefusesSocialActions(t *testing.T) {
+	ctx := context.Background()
+	store := account.NewStore(testDB)
+	svc := newSocialService()
+	deleter := accountdelete.NewDeleter(testDB)
+
+	_, seats := newGameWithSeats(t, 2) // a shared game: the befriend-an-opponent gate
+	viewer, gone := seats[0], seats[1]
+
+	if err := svc.SendFriendRequest(ctx, viewer, gone); err != nil {
+		t.Fatalf("friend request before deletion = %v, want nil", err)
+	}
+	if err := deleter.AnonymizeAndTombstone(ctx, gone); err != nil {
+		t.Fatalf("delete: %v", err)
+	}
+
+	// Deletion dropped the pending request with the rest of the account's social rows, so
+	// this is a fresh request against the tombstone — exactly what an older client sends
+	// after the 🤝 reappears on the finished game's scoreboard.
+	if err := svc.SendFriendRequest(ctx, viewer, gone); !errors.Is(err, social.ErrAccountDeleted) {
+		t.Errorf("friend request to a deleted account = %v, want ErrAccountDeleted", err)
+	}
+	if err := svc.Block(ctx, viewer, gone); !errors.Is(err, social.ErrAccountDeleted) {
+		t.Errorf("block of a deleted account = %v, want ErrAccountDeleted", err)
+	}
+	// The live opponent stays actionable — the guard is per-account, not a blanket switch.
+	live := provisionAccount(t)
+	if err := svc.Block(ctx, viewer, live); err != nil {
+		t.Errorf("block of a live account = %v, want nil", err)
+	}
+
+	deleted, err := store.DeletedIDs(ctx, []uuid.UUID{viewer, gone})
+	if err != nil {
+		t.Fatalf("deleted ids: %v", err)
+	}
+	if !deleted[gone] {
+		t.Error("the deleted account must be marked deleted")
+	}
+	if deleted[viewer] {
+		t.Error("a live account must not be marked deleted")
+	}
+}
+
+// TestGameStateMarksDeletedSeat: the per-viewer game state marks the seat of a deleted
+// opponent, which is what hides the in-game social controls (add-friend, block, chat, nudge)
+// on the client; the viewer's own live seat stays unmarked.
+func TestGameStateMarksDeletedSeat(t *testing.T) {
+	ctx := context.Background()
+	games := newGameService()
+	seats := []uuid.UUID{provisionAccount(t), provisionAccount(t)}
+	g, err := games.Create(ctx, game.CreateParams{
+		Variant: engine.VariantEnglish, Seats: seats, TurnTimeout: 24 * time.Hour, Seed: openingSeed(t),
+	})
+	if err != nil {
+		t.Fatalf("create game: %v", err)
+	}
+	srv := server.New(":0", server.Deps{
+		Logger:   zaptest.NewLogger(t),
+		DB:       testDB,
+		Accounts: account.NewStore(testDB),
+		Games:    games,
+	})
+	viewer, gone := seats[0], seats[1]
+
+	if marks := stateSeatDeleted(t, srv, g.ID, viewer); marks[0] || marks[1] {
+		t.Fatalf("before deletion no seat may be marked deleted, got %v", marks)
+	}
+	if err := accountdelete.NewDeleter(testDB).AnonymizeAndTombstone(ctx, gone); err != nil {
+		t.Fatalf("delete: %v", err)
+	}
+	marks := stateSeatDeleted(t, srv, g.ID, viewer)
+	if marks[0] {
+		t.Error("the viewer's own live seat must not be marked deleted")
+	}
+	if !marks[1] {
+		t.Error("the deleted opponent's seat must be marked deleted")
+	}
+}
+
+// stateSeatDeleted fetches viewer's game state and returns the seats' deleted marks, indexed
+// by seat.
+func stateSeatDeleted(t *testing.T, srv *server.Server, gameID, viewer uuid.UUID) map[int]bool {
+	t.Helper()
+	rec := userGet(t, srv, "/api/v1/user/games/"+gameID.String()+"/state", viewer)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("game state = %d (%s), want 200", rec.Code, rec.Body.String())
+	}
+	var body struct {
+		Game struct {
+			Seats []struct {
+				Seat    int  `json:"seat"`
+				Deleted bool `json:"deleted"`
+			} `json:"seats"`
+		} `json:"game"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("decode game state: %v", err)
+	}
+	out := map[int]bool{}
+	for _, s := range body.Game.Seats {
+		out[s.Seat] = s.Deleted
+	}
+	return out
+}
+
 // TestDeleteStepUpEmail: an email account's delete code verifies (wrong code rejected, no
 // deeplink in the mail); a platform-only account has no email and cannot request a code.
 func TestDeleteStepUpEmail(t *testing.T) {
diff --git a/backend/internal/server/dto.go b/backend/internal/server/dto.go
index a4c2dba..23b7ce2 100644
--- a/backend/internal/server/dto.go
+++ b/backend/internal/server/dto.go
@@ -132,6 +132,10 @@ type seatDTO struct {
 	Score       int    `json:"score"`
 	HintsUsed   int    `json:"hints_used"`
 	IsWinner    bool   `json:"is_winner"`
+	// Deleted marks a seat whose account has been deleted: the client hides every social
+	// control aimed at it (add-friend, block, chat, nudge). gameDTOFromGame leaves it false
+	// (it does not reach the account store); fillSeatDeleted fills it.
+	Deleted bool `json:"deleted"`
 }
 
 // gameDTO is the shared game summary.
diff --git a/backend/internal/server/handlers.go b/backend/internal/server/handlers.go
index 5176daf..f8dece0 100644
--- a/backend/internal/server/handlers.go
+++ b/backend/internal/server/handlers.go
@@ -314,6 +314,8 @@ func statusForError(err error) (int, string) {
 		return http.StatusConflict, "request_exists"
 	case errors.Is(err, social.ErrRequestBlocked):
 		return http.StatusForbidden, "request_blocked"
+	case errors.Is(err, social.ErrAccountDeleted):
+		return http.StatusGone, "account_deleted"
 	case errors.Is(err, social.ErrRequestNotFound):
 		return http.StatusNotFound, "request_not_found"
 	case errors.Is(err, social.ErrNoSharedGame):
diff --git a/backend/internal/server/handlers_game.go b/backend/internal/server/handlers_game.go
index b3a25cd..afd39a6 100644
--- a/backend/internal/server/handlers_game.go
+++ b/backend/internal/server/handlers_game.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
+	"go.uber.org/zap"
 
 	"scrabble/backend/internal/engine"
 	"scrabble/backend/internal/game"
@@ -97,6 +98,42 @@ func (s *Server) fillSeatNames(ctx context.Context, g *gameDTO, memo map[string]
 	}
 }
 
+// fillSeatDeleted marks each seat whose account has been deleted, memoising across seats and
+// games within one request (the same shape as fillSeatNames) and resolving the seats still
+// unknown in a single batch query. A seat with no account (an open game's empty seat) is
+// skipped. It is best-effort: on a store error the seats keep the false the projection left,
+// which only leaves the social controls as they were before.
+func (s *Server) fillSeatDeleted(ctx context.Context, g *gameDTO, memo map[string]bool) {
+	var ask []uuid.UUID
+	for _, seat := range g.Seats {
+		if seat.AccountID == "" {
+			continue
+		}
+		if _, ok := memo[seat.AccountID]; ok {
+			continue
+		}
+		uid, err := uuid.Parse(seat.AccountID)
+		if err != nil {
+			memo[seat.AccountID] = false
+			continue
+		}
+		memo[seat.AccountID] = false // resolved below; a failed lookup stays false
+		ask = append(ask, uid)
+	}
+	if len(ask) > 0 {
+		deleted, err := s.accounts.DeletedIDs(ctx, ask)
+		if err != nil {
+			s.log.Warn("seat deleted marks failed", zap.Error(err))
+		}
+		for id := range deleted {
+			memo[id.String()] = true
+		}
+	}
+	for i := range g.Seats {
+		g.Seats[i].Deleted = memo[g.Seats[i].AccountID]
+	}
+}
+
 // moveRecordDTOFromHistory projects a journal move into the shared move DTO.
 func moveRecordDTOFromHistory(m game.HistoryMove) moveRecordDTO {
 	tiles := make([]tileDTO, 0, len(m.Tiles))
@@ -435,6 +472,7 @@ func (s *Server) handleListGames(c *gin.Context) {
 		return
 	}
 	memo := map[string]string{}
+	delMemo := map[string]bool{}
 	// Two queries seed the lobby's per-card unread badge for every listed game: which games have
 	// any unread entry, and which of those have a real message (so the badge can colour
 	// message-bearing games apart from nudge-only ones).
@@ -447,6 +485,7 @@ func (s *Server) handleListGames(c *gin.Context) {
 	for _, g := range games {
 		dto := gameDTOFromGame(g)
 		s.fillSeatNames(c.Request.Context(), &dto, memo)
+		s.fillSeatDeleted(c.Request.Context(), &dto, delMemo)
 		dto.UnreadChat = unread[g.ID]
 		dto.UnreadMessages = unreadMsg[g.ID]
 		out = append(out, dto)
@@ -526,6 +565,7 @@ func (s *Server) writeMoveResult(c *gin.Context, res game.MoveResult) {
 		return
 	}
 	s.fillSeatNames(c.Request.Context(), &dto.Game, map[string]string{})
+	s.fillSeatDeleted(c.Request.Context(), &dto.Game, map[string]bool{})
 	if uid, ok := userID(c); ok {
 		s.setUnreadChat(c.Request.Context(), &dto.Game, uid)
 	}
diff --git a/backend/internal/server/handlers_user.go b/backend/internal/server/handlers_user.go
index 493dc59..937b838 100644
--- a/backend/internal/server/handlers_user.go
+++ b/backend/internal/server/handlers_user.go
@@ -137,6 +137,7 @@ func (s *Server) handleGameState(c *gin.Context) {
 		return
 	}
 	s.fillSeatNames(c.Request.Context(), &dto.Game, map[string]string{})
+	s.fillSeatDeleted(c.Request.Context(), &dto.Game, map[string]bool{})
 	s.setUnreadChat(c.Request.Context(), &dto.Game, uid)
 	c.JSON(http.StatusOK, dto)
 }
@@ -207,6 +208,7 @@ func (s *Server) handleEnqueue(c *gin.Context) {
 	dto := matchDTOFrom(res)
 	if dto.Game != nil {
 		s.fillSeatNames(c.Request.Context(), dto.Game, map[string]string{})
+		s.fillSeatDeleted(c.Request.Context(), dto.Game, map[string]bool{})
 	}
 	c.JSON(http.StatusOK, dto)
 }
diff --git a/backend/internal/social/blocks.go b/backend/internal/social/blocks.go
index 998e805..3863640 100644
--- a/backend/internal/social/blocks.go
+++ b/backend/internal/social/blocks.go
@@ -28,6 +28,16 @@ func (svc *Service) Block(ctx context.Context, blockerID, blockedID uuid.UUID) e
 	if blockerID == blockedID {
 		return ErrSelfRelation
 	}
+	// A deleted account sends nothing there is anything left to suppress, and the block would
+	// outlive the retention purge as a dangling row: refuse it. The client already hides the
+	// control on a deleted seat; this guard catches an older one.
+	blocked, err := svc.accounts.GetByID(ctx, blockedID)
+	if err != nil {
+		return err
+	}
+	if blocked.Deleted {
+		return ErrAccountDeleted
+	}
 	if err := svc.store.insertBlock(ctx, blockerID, blockedID); err != nil {
 		return err
 	}
diff --git a/backend/internal/social/friends.go b/backend/internal/social/friends.go
index c48b8cf..badc977 100644
--- a/backend/internal/social/friends.go
+++ b/backend/internal/social/friends.go
@@ -73,6 +73,11 @@ func (svc *Service) SendFriendRequest(ctx context.Context, requesterID, addresse
 		}
 		return err
 	}
+	if addressee.Deleted {
+		// The addressee deleted their account: there is nobody to answer the request, so it is
+		// refused rather than left pending forever.
+		return ErrAccountDeleted
+	}
 	if iBlockThem {
 		// The requester has blocked the addressee — they are the blocker and aware of it.
 		return ErrRequestBlocked
diff --git a/backend/internal/social/social.go b/backend/internal/social/social.go
index d704e80..661880a 100644
--- a/backend/internal/social/social.go
+++ b/backend/internal/social/social.go
@@ -62,6 +62,11 @@ var (
 	// ErrGuestForbidden is returned when a guest attempts a durable-only action (send a friend
 	// request, redeem a friend code); friends are a durable-account feature.
 	ErrGuestForbidden = errors.New("social: guests cannot use friends")
+	// ErrAccountDeleted is returned when a social action targets a deleted (tombstoned)
+	// account: nobody is behind it any more, so it can be neither befriended nor blocked.
+	// The client already hides those controls on a deleted seat; this is the server source
+	// of truth, and the guard an older client hits.
+	ErrAccountDeleted = errors.New("social: this account has been deleted")
 	// ErrRequestNotFound is returned when no pending friend request matches.
 	ErrRequestNotFound = errors.New("social: no pending friend request")
 	// ErrNoSharedGame is returned when a friend request targets someone the
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 916f54e..4f95ad3 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -398,6 +398,16 @@ arrive from a platform rather than completing a mandatory registration).
   full timeline. (A merge that would otherwise leave the survivor with two identities of one
   kind — e.g. each account held a confirmed email — keeps the primary's and journals the
   secondary's with `reason=merge` before dropping it.)
+  A tombstoned account **takes part in no further social exchange**: the per-viewer game
+  views mark its seats (`SeatView.deleted`, resolved by a batch `accounts.deleted_at`
+  lookup beside the seat display names), and the client hides every control aimed at such a
+  seat — add-friend, block, and the chat composer (message + nudge) once no reachable
+  opponent is left. The live events carry the seat standings the game domain holds and so
+  leave the mark unset; the client seeds it from the REST-backed views and the delta
+  reducers preserve it. The server is the source of truth for an older client:
+  `SendFriendRequest` and `Block` against a tombstone return `social.ErrAccountDeleted`
+  (HTTP 410, code `account_deleted`) — otherwise a request would hang pending forever,
+  since deletion already dropped the account's social rows.
   Step-up is a mailed code (`purpose=delete`, no deeplink — a stray click must not delete;
   `ConfirmByToken` refuses a delete token) for an email account, else a typed phrase.
   `last_login_at` / `last_login_ip` are stamped on the cold-load profile fetch (throttled
diff --git a/docs/FUNCTIONAL.md b/docs/FUNCTIONAL.md
index 69f6dbe..f82a2d8 100644
--- a/docs/FUNCTIONAL.md
+++ b/docs/FUNCTIONAL.md
@@ -374,7 +374,12 @@ goes **disabled** while a request is pending or was declined and **disappears**
 friends; both controls **disappear and the opponent's name is struck through** once you have
 blocked them. They update in place the moment the relationship changes and stay correct across
 reloads. Applying a block (or friend request) takes effect immediately and is confirmed by a
-live event; a transport failure rolls the control back to its prior state.
+live event; a transport failure rolls the control back to its prior state. Once an opponent
+**deletes their account** there is nobody left to reach, so both controls disappear for that
+seat for good — in the finished game as much as in one still running — and the chat composer
+goes too (message and nudge) when no reachable opponent remains; the chat log and the game
+itself stay readable. Attempting either action anyway (an app version that still shows the
+controls) is refused with *This player has deleted their account*.
 
 Block globally — switch off incoming chat and/or friend requests — or block an **individual
 player**. A per-user block is **one-directional and silent**: you stop receiving everything
diff --git a/docs/FUNCTIONAL_ru.md b/docs/FUNCTIONAL_ru.md
index 8254c5e..ee3e542 100644
--- a/docs/FUNCTIONAL_ru.md
+++ b/docs/FUNCTIONAL_ru.md
@@ -377,7 +377,12 @@ Telegram/VK** — в отличие от офлайн-режима игры вы
 **исчезает** после принятия; **оба контрола исчезают, а имя соперника становится зачёркнутым**
 после блокировки. Они обновляются на месте в момент изменения отношения и остаются верны после
 перезагрузки. Блокировка (как и заявка в друзья) применяется немедленно и подтверждается живым
-событием; при сбое транспорта контрол возвращается в прежнее состояние.
+событием; при сбое транспорта контрол возвращается в прежнее состояние. Если соперник **удалил
+свою учётную запись**, обращаться больше не к кому: оба контрола на этом месте исчезают
+навсегда — и в завершённой партии, и в идущей, — а когда доступных соперников не остаётся,
+пропадает и поле чата (сообщение и nudge); сама переписка и партия остаются доступны для
+чтения. Попытка выполнить действие всё равно (версия приложения, которая ещё показывает
+контролы) отклоняется сообщением *Игрок удалил свою учётную запись*.
 
 Глобальная блокировка — отключить входящие чат и/или заявки — либо блокировка **конкретного
 игрока**. Пер-юзер блок **односторонний и незаметный**: вы перестаёте получать от этого человека
diff --git a/gateway/internal/backendclient/api.go b/gateway/internal/backendclient/api.go
index e4bf934..a41b6ab 100644
--- a/gateway/internal/backendclient/api.go
+++ b/gateway/internal/backendclient/api.go
@@ -153,7 +153,8 @@ type MoveRecordResp struct {
 	Total   int        `json:"total"`
 }
 
-// SeatResp is one seat's public standing.
+// SeatResp is one seat's public standing. Deleted marks a seat whose account has been
+// deleted, so the client can hide the social controls aimed at it.
 type SeatResp struct {
 	Seat        int    `json:"seat"`
 	AccountID   string `json:"account_id"`
@@ -161,6 +162,7 @@ type SeatResp struct {
 	Score       int    `json:"score"`
 	HintsUsed   int    `json:"hints_used"`
 	IsWinner    bool   `json:"is_winner"`
+	Deleted     bool   `json:"deleted"`
 }
 
 // GameResp is the shared game summary.
diff --git a/gateway/internal/transcode/encode.go b/gateway/internal/transcode/encode.go
index 8f9f9aa..c219408 100644
--- a/gateway/internal/transcode/encode.go
+++ b/gateway/internal/transcode/encode.go
@@ -618,6 +618,7 @@ func toWireGame(g backendclient.GameResp) wire.GameView {
 			HintsUsed:   s.HintsUsed,
 			IsWinner:    s.IsWinner,
 			DisplayName: s.DisplayName,
+			Deleted:     s.Deleted,
 		}
 	}
 	return wire.GameView{
diff --git a/gateway/internal/transcode/transcode_test.go b/gateway/internal/transcode/transcode_test.go
index 267b60e..15783c0 100644
--- a/gateway/internal/transcode/transcode_test.go
+++ b/gateway/internal/transcode/transcode_test.go
@@ -300,7 +300,7 @@ func TestGamesListRoundTripDecodesSeatNames(t *testing.T) {
 		if r.URL.Path != "/api/v1/user/games" {
 			t.Errorf("unexpected path %q", r.URL.Path)
 		}
-		_, _ = w.Write([]byte(`{"games":[{"id":"g-1","variant":"scrabble_en","status":"active","players":2,"to_move":0,"last_activity_unix":1717000000,"unread_chat":true,"unread_messages":true,"seats":[{"seat":0,"account_id":"u-9","display_name":"You","score":10},{"seat":1,"account_id":"a-1","display_name":"Ann","score":7}]}],"at_game_limit":true}`))
+		_, _ = w.Write([]byte(`{"games":[{"id":"g-1","variant":"scrabble_en","status":"active","players":2,"to_move":0,"last_activity_unix":1717000000,"unread_chat":true,"unread_messages":true,"seats":[{"seat":0,"account_id":"u-9","display_name":"You","score":10},{"seat":1,"account_id":"a-1","display_name":"Ann","score":7,"deleted":true}]}],"at_game_limit":true}`))
 	})
 	defer cleanup()
 
@@ -333,6 +333,14 @@ func TestGamesListRoundTripDecodesSeatNames(t *testing.T) {
 	if string(seat.DisplayName()) != "Ann" {
 		t.Errorf("seat display name = %q, want Ann", seat.DisplayName())
 	}
+	if !seat.Deleted() {
+		t.Error("seat deleted = false, want true (the backend marked the seat's account deleted)")
+	}
+	var own fb.SeatView
+	g.Seats(&own, 0)
+	if own.Deleted() {
+		t.Error("seat deleted = true for a live account, want false")
+	}
 	if !gl.AtGameLimit() {
 		t.Error("at_game_limit = false, want true (the backend reported the cap)")
 	}
diff --git a/pkg/fbs/scrabble.fbs b/pkg/fbs/scrabble.fbs
index 55ef736..5f2c553 100644
--- a/pkg/fbs/scrabble.fbs
+++ b/pkg/fbs/scrabble.fbs
@@ -44,7 +44,9 @@ table AlphabetEntry {
 }
 
 // SeatView is one seat's public standing in a game. display_name is resolved by the
-// backend from the account store (added trailing — backward-compatible).
+// backend from the account store (added trailing — backward-compatible). deleted marks a
+// seat whose account has been deleted (tombstoned): the client hides every social control
+// aimed at it — add-friend, block, chat and nudge (added trailing).
 table SeatView {
   seat:int;
   account_id:string;
@@ -52,6 +54,7 @@ table SeatView {
   hints_used:int;
   is_winner:bool;
   display_name:string;
+  deleted:bool;
 }
 
 // GameView is the shared (non-private) game summary.
diff --git a/pkg/fbs/scrabblefb/SeatView.go b/pkg/fbs/scrabblefb/SeatView.go
index f9d78e2..d52976f 100644
--- a/pkg/fbs/scrabblefb/SeatView.go
+++ b/pkg/fbs/scrabblefb/SeatView.go
@@ -105,8 +105,20 @@ func (rcv *SeatView) DisplayName() []byte {
 	return nil
 }
 
+func (rcv *SeatView) Deleted() bool {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(16))
+	if o != 0 {
+		return rcv._tab.GetBool(o + rcv._tab.Pos)
+	}
+	return false
+}
+
+func (rcv *SeatView) MutateDeleted(n bool) bool {
+	return rcv._tab.MutateBoolSlot(16, n)
+}
+
 func SeatViewStart(builder *flatbuffers.Builder) {
-	builder.StartObject(6)
+	builder.StartObject(7)
 }
 func SeatViewAddSeat(builder *flatbuffers.Builder, seat int32) {
 	builder.PrependInt32Slot(0, seat, 0)
@@ -126,6 +138,9 @@ func SeatViewAddIsWinner(builder *flatbuffers.Builder, isWinner bool) {
 func SeatViewAddDisplayName(builder *flatbuffers.Builder, displayName flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(5, flatbuffers.UOffsetT(displayName), 0)
 }
+func SeatViewAddDeleted(builder *flatbuffers.Builder, deleted bool) {
+	builder.PrependBoolSlot(6, deleted, false)
+}
 func SeatViewEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
 	return builder.EndObject()
 }
diff --git a/pkg/wire/build.go b/pkg/wire/build.go
index 5fd62dd..3ab30d8 100644
--- a/pkg/wire/build.go
+++ b/pkg/wire/build.go
@@ -26,6 +26,9 @@ type SeatView struct {
 	HintsUsed   int
 	IsWinner    bool
 	DisplayName string
+	// Deleted marks a seat whose account has been deleted (tombstoned): the client hides
+	// every social control aimed at it — add-friend, block, chat and nudge.
+	Deleted bool
 }
 
 // GameView is the shared, non-private game summary.
@@ -142,6 +145,7 @@ func BuildGameView(b *flatbuffers.Builder, g GameView) flatbuffers.UOffsetT {
 		fb.SeatViewAddHintsUsed(b, int32(s.HintsUsed))
 		fb.SeatViewAddIsWinner(b, s.IsWinner)
 		fb.SeatViewAddDisplayName(b, dname)
+		fb.SeatViewAddDeleted(b, s.Deleted)
 		seatOffs[i] = fb.SeatViewEnd(b)
 	}
 	fb.GameViewStartSeatsVector(b, len(seatOffs))
diff --git a/ui/src/game/Chat.svelte b/ui/src/game/Chat.svelte
index e58199d..df74b30 100644
--- a/ui/src/game/Chat.svelte
+++ b/ui/src/game/Chat.svelte
@@ -40,8 +40,8 @@
     // nobody to message or hurry. The fields still show (turn-driven), but disabled.
     vsAi?: boolean;
     // blocked hides the whole composer (message field, send and nudge), leaving only the chat
-    // log — as in a finished game — when the viewer has blocked the opponent: there is no one
-    // they will message (the backend rejects it too).
+    // log — as in a finished game — when no opponent can be reached: the viewer has blocked them
+    // (the backend rejects it too), or their account has been deleted.
     blocked?: boolean;
     onsend: (text: string) => void;
     onnudge: () => void;
diff --git a/ui/src/game/ChatScreen.svelte b/ui/src/game/ChatScreen.svelte
index 1beef2c..49bd8aa 100644
--- a/ui/src/game/ChatScreen.svelte
+++ b/ui/src/game/ChatScreen.svelte
@@ -36,15 +36,16 @@
   const canNudge = $derived(!!view && view.game.status === 'active' && view.game.toMove !== view.seat);
   // While the auto-match game still has no opponent, chat and nudge are both disabled.
   const waiting = $derived(!!view && view.game.status === 'open');
-  // peerBlocked is true when every seated opponent is one the viewer has blocked: the whole
-  // composer is then hidden (a blocked opponent cannot be messaged).
-  const peerBlocked = $derived.by(() => {
+  // peerUnreachable is true when no seated opponent can be reached — each is either one the viewer
+  // has blocked or a deleted account: the whole composer (message field, send and nudge) is then
+  // hidden, leaving only the chat log.
+  const peerUnreachable = $derived.by(() => {
     const v = view;
     if (!v) return false;
     const opponents = v.game.seats.filter((s) => s.seat !== v.seat && !!s.accountId);
     return (
       opponents.length > 0 &&
-      opponents.every((s) => blockedIds.has(s.accountId) || blockedRobotSeats.has(s.seat))
+      opponents.every((s) => s.deleted || blockedIds.has(s.accountId) || blockedRobotSeats.has(s.seat))
     );
   });
   const nudgeCooldownSecs = 3600;
@@ -155,7 +156,7 @@
   {waiting}
   {nudgeOnCooldown}
   vsAi={!!view && view.game.vsAi}
-  blocked={peerBlocked}
+  blocked={peerUnreachable}
   onsend={sendChat}
   onnudge={nudge}
 />
diff --git a/ui/src/game/Game.svelte b/ui/src/game/Game.svelte
index 2e21ee4..47be9db 100644
--- a/ui/src/game/Game.svelte
+++ b/ui/src/game/Game.svelte
@@ -1472,13 +1472,15 @@
   // canAddFriend reports whether a seat shows the 🤝: a non-guest viewing a seated opponent
   // (not the still-empty seat of an open game) who is not yet a friend (an already-requested
   // opponent still shows it, but disabled).
-  function canAddFriend(s: { accountId: string; seat: number }): boolean {
-    // Never offer add-friend against an AI opponent, an existing friend, or a blocked player — nor in
-    // a local (offline) game, whose seats are account-less: vs_ai, and hotseat's synthetic seat ids.
+  function canAddFriend(s: { accountId: string; seat: number; deleted?: boolean }): boolean {
+    // Never offer add-friend against an AI opponent, an existing friend, a blocked player or a
+    // deleted account — nor in a local (offline) game, whose seats are account-less: vs_ai, and
+    // hotseat's synthetic seat ids.
     if (view?.game.vsAi || isLocalGameId(id)) return false;
     return (
       netReady &&
       !!s.accountId &&
+      !s.deleted &&
       !app.profile?.isGuest &&
       s.accountId !== app.session?.userId &&
       !friends.has(s.accountId) &&
@@ -1488,10 +1490,18 @@
 
   // canBlock reports whether a seat shows the ✖️ block control: like canAddFriend, but a friend
   // may still be blocked (the block overrides the friendship), so it omits the friend exclusion.
-  // An already-blocked opponent hides it (both controls go, and the name is struck).
-  function canBlock(s: { accountId: string; seat: number }): boolean {
+  // An already-blocked opponent hides it (both controls go, and the name is struck); a deleted
+  // account hides it too — there is nobody left to block.
+  function canBlock(s: { accountId: string; seat: number; deleted?: boolean }): boolean {
     if (view?.game.vsAi || isLocalGameId(id)) return false;
-    return netReady && !!s.accountId && !app.profile?.isGuest && s.accountId !== app.session?.userId && !seatBlocked(s);
+    return (
+      netReady &&
+      !!s.accountId &&
+      !s.deleted &&
+      !app.profile?.isGuest &&
+      s.accountId !== app.session?.userId &&
+      !seatBlocked(s)
+    );
   }
 </script>
 
diff --git a/ui/src/gen/fbs/scrabblefb/seat-view.ts b/ui/src/gen/fbs/scrabblefb/seat-view.ts
index 9d253be..48adff6 100644
--- a/ui/src/gen/fbs/scrabblefb/seat-view.ts
+++ b/ui/src/gen/fbs/scrabblefb/seat-view.ts
@@ -54,8 +54,13 @@ displayName(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
+deleted():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 static startSeatView(builder:flatbuffers.Builder) {
-  builder.startObject(6);
+  builder.startObject(7);
 }
 
 static addSeat(builder:flatbuffers.Builder, seat:number) {
@@ -82,12 +87,16 @@ static addDisplayName(builder:flatbuffers.Builder, displayNameOffset:flatbuffers
   builder.addFieldOffset(5, displayNameOffset, 0);
 }
 
+static addDeleted(builder:flatbuffers.Builder, deleted:boolean) {
+  builder.addFieldInt8(6, +deleted, +false);
+}
+
 static endSeatView(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createSeatView(builder:flatbuffers.Builder, seat:number, accountIdOffset:flatbuffers.Offset, score:number, hintsUsed:number, isWinner:boolean, displayNameOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createSeatView(builder:flatbuffers.Builder, seat:number, accountIdOffset:flatbuffers.Offset, score:number, hintsUsed:number, isWinner:boolean, displayNameOffset:flatbuffers.Offset, deleted:boolean):flatbuffers.Offset {
   SeatView.startSeatView(builder);
   SeatView.addSeat(builder, seat);
   SeatView.addAccountId(builder, accountIdOffset);
@@ -95,6 +104,7 @@ static createSeatView(builder:flatbuffers.Builder, seat:number, accountIdOffset:
   SeatView.addHintsUsed(builder, hintsUsed);
   SeatView.addIsWinner(builder, isWinner);
   SeatView.addDisplayName(builder, displayNameOffset);
+  SeatView.addDeleted(builder, deleted);
   return SeatView.endSeatView(builder);
 }
 }
diff --git a/ui/src/lib/codec.test.ts b/ui/src/lib/codec.test.ts
index bec02e8..fc7fdd3 100644
--- a/ui/src/lib/codec.test.ts
+++ b/ui/src/lib/codec.test.ts
@@ -400,6 +400,7 @@ describe('codec', () => {
     fb.SeatView.addHintsUsed(b, 0);
     fb.SeatView.addIsWinner(b, false);
     fb.SeatView.addDisplayName(b, dn);
+    fb.SeatView.addDeleted(b, true);
     const seat = fb.SeatView.endSeatView(b);
     const seats = fb.GameView.createSeatsVector(b, [seat]);
     const id = b.createString('g1');
@@ -434,6 +435,8 @@ describe('codec', () => {
     expect(gl.games[0].id).toBe('g1');
     expect(gl.games[0].seats[0].displayName).toBe('Ann');
     expect(gl.games[0].seats[0].score).toBe(13);
+    // The deleted mark rides the seat: it hides the social controls aimed at that seat.
+    expect(gl.games[0].seats[0].deleted).toBe(true);
     expect(gl.games[0].lastActivityUnix).toBe(1717000000);
     expect(gl.games[0].vsAi).toBe(true);
     expect(gl.games[0].unreadChat).toBe(true);
diff --git a/ui/src/lib/codec.ts b/ui/src/lib/codec.ts
index d4135c4..1a3500a 100644
--- a/ui/src/lib/codec.ts
+++ b/ui/src/lib/codec.ts
@@ -291,6 +291,7 @@ function decodeSeat(v: fb.SeatView): Seat {
     score: v.score(),
     hintsUsed: v.hintsUsed(),
     isWinner: v.isWinner(),
+    deleted: v.deleted(),
   };
 }
 
diff --git a/ui/src/lib/gamedelta.test.ts b/ui/src/lib/gamedelta.test.ts
index b3d0760..5349f8c 100644
--- a/ui/src/lib/gamedelta.test.ts
+++ b/ui/src/lib/gamedelta.test.ts
@@ -103,6 +103,47 @@ describe('applyGameOver', () => {
   });
 });
 
+describe('deleted seat marks', () => {
+  // The live events carry no deleted mark (only the REST-backed views resolve it), so a delta must
+  // not clear the mark the cache already holds — otherwise the social controls aimed at a deleted
+  // opponent reappear until the next cold load.
+  function cacheWithDeletedSeat(moveCount: number): CachedGame {
+    const c = cache(moveCount);
+    c.view.game.seats = [
+      { seat: 0, accountId: 'me', displayName: 'Me', score: 0, hintsUsed: 0, isWinner: false },
+      { seat: 1, accountId: 'gone', displayName: '[Deleted]', score: 0, hintsUsed: 0, isWinner: false, deleted: true },
+    ];
+    return c;
+  }
+
+  function eventSeats(): GameView['seats'] {
+    return [
+      { seat: 0, accountId: 'me', displayName: 'Me', score: 0, hintsUsed: 0, isWinner: false },
+      { seat: 1, accountId: 'gone', displayName: '[Deleted]', score: 12, hintsUsed: 0, isWinner: false },
+    ];
+  }
+
+  it('keeps a deleted seat marked across a move delta', () => {
+    const d = delta(4, 1);
+    d.game = { ...gameView(4), seats: eventSeats() };
+    const res = applyMoveDelta(cacheWithDeletedSeat(3), d);
+    expect(res.cache?.view.game.seats.map((s) => !!s.deleted)).toEqual([false, true]);
+    expect(res.cache?.view.game.seats[1].score).toBe(12); // the event's own fields still win
+  });
+
+  it('keeps a deleted seat marked across the final summary', () => {
+    const final: GameView = { ...gameView(3, true), seats: eventSeats() };
+    const res = applyGameOver(cacheWithDeletedSeat(3), final);
+    expect(res.cache?.view.game.seats.map((s) => !!s.deleted)).toEqual([false, true]);
+  });
+
+  it('leaves the event seats untouched when no cached seat is deleted', () => {
+    const final: GameView = { ...gameView(3, true), seats: eventSeats() };
+    const res = applyGameOver(cache(3), final);
+    expect(res.cache?.view.game.seats).toBe(final.seats);
+  });
+});
+
 function movedEvent(moveCount: number, player: number, bagLen = 45): PushEvent {
   return { kind: 'opponent_moved', gameId: 'g1', move: move(player), game: gameView(moveCount), bagLen };
 }
diff --git a/ui/src/lib/gamedelta.ts b/ui/src/lib/gamedelta.ts
index b5ead5c..c6e8bdb 100644
--- a/ui/src/lib/gamedelta.ts
+++ b/ui/src/lib/gamedelta.ts
@@ -23,6 +23,19 @@ export interface DeltaResult {
   refetch: boolean;
 }
 
+/**
+ * keepDeletedMarks carries the seats' deleted marks from the cached game over to a game view that
+ * arrived on the live stream. The mark says the seat's account has been deleted; only the REST-backed
+ * views resolve it (the events carry the seat standings the game domain holds, with no account-store
+ * lookup), so without this a live move or the final summary would clear it and the social controls
+ * aimed at a deleted seat would reappear until the next cold load.
+ */
+function keepDeletedMarks(prev: GameView, next: GameView): GameView {
+  if (!prev.seats.some((s) => s.deleted)) return next;
+  const wasDeleted = new Set(prev.seats.filter((s) => s.deleted).map((s) => s.seat));
+  return { ...next, seats: next.seats.map((s) => (wasDeleted.has(s.seat) ? { ...s, deleted: true } : s)) };
+}
+
 /**
  * seedInitialState builds a fresh cache entry from a started game's initial view (match_found /
  * game_started). A freshly started game has no moves, so the board replays from an empty journal.
@@ -50,7 +63,7 @@ export function applyMoveDelta(cached: CachedGame | undefined, d: MoveDelta): De
   if (next > have + 1) return { refetch: true }; // a gap — an intermediate move was missed
   // The actor's own move changed their rack (a draw), which opponent_moved does not carry.
   if (d.move.player === cached.view.seat) return { refetch: true };
-  const view: StateView = { ...cached.view, game: d.game, bagLen: d.bagLen };
+  const view: StateView = { ...cached.view, game: keepDeletedMarks(cached.view.game, d.game), bagLen: d.bagLen };
   return { cache: { view, moves: [...cached.moves, d.move] }, refetch: false };
 }
 
@@ -64,7 +77,7 @@ export function applyGameOver(cached: CachedGame | undefined, game: GameView | u
   if (!cached) return { refetch: false };
   if (!game) return { refetch: cached.view.game.status !== 'finished' };
   if (cached.view.game.moveCount < game.moveCount) return { refetch: true };
-  const view: StateView = { ...cached.view, game };
+  const view: StateView = { ...cached.view, game: keepDeletedMarks(cached.view.game, game) };
   return { cache: { view, moves: cached.moves }, refetch: false };
 }
 
diff --git a/ui/src/lib/i18n/en.ts b/ui/src/lib/i18n/en.ts
index ef4ed52..55fe818 100644
--- a/ui/src/lib/i18n/en.ts
+++ b/ui/src/lib/i18n/en.ts
@@ -434,6 +434,7 @@ export const en = {
   'error.request_not_found': 'No matching friend request.',
   'error.no_shared_game': 'You can only add someone you have played with.',
   'error.request_declined': 'This player declined your request.',
+  'error.account_deleted': 'This player has deleted their account.',
   'error.friend_code_invalid': 'That friend code is invalid or expired.',
   'error.invalid_invitation': 'Invalid invitation.',
   'error.invitation_blocked': 'You cannot invite this player.',
diff --git a/ui/src/lib/i18n/ru.ts b/ui/src/lib/i18n/ru.ts
index d29fc5d..1af501d 100644
--- a/ui/src/lib/i18n/ru.ts
+++ b/ui/src/lib/i18n/ru.ts
@@ -434,6 +434,7 @@ export const ru: Record<MessageKey, string> = {
   'error.request_not_found': 'Подходящей заявки нет.',
   'error.no_shared_game': 'Можно добавить только того, с кем вы играли.',
   'error.request_declined': 'Игрок отклонил вашу заявку.',
+  'error.account_deleted': 'Игрок удалил свою учётную запись.',
   'error.friend_code_invalid': 'Код недействителен или истёк.',
   'error.invalid_invitation': 'Неверное приглашение.',
   'error.invitation_blocked': 'Нельзя пригласить этого игрока.',
diff --git a/ui/src/lib/model.ts b/ui/src/lib/model.ts
index 34f1146..a5d90df 100644
--- a/ui/src/lib/model.ts
+++ b/ui/src/lib/model.ts
@@ -32,6 +32,10 @@ export interface Seat {
   /** Offline hotseat only: the seat resigned or was excluded by the host. Set by the local source so
    *  the finished-game medal ranking can place it last (no medal); undefined for online seats. */
   resigned?: boolean;
+  /** The seat's account has been deleted: every social control aimed at it is hidden (add-friend,
+   *  block, chat, nudge) — there is nobody behind it any more. Carried by the REST-backed views
+   *  only; the live events leave it unset, so the delta reducers preserve the cached value. */
+  deleted?: boolean;
 }
 
 export interface GameView {