PRERELEASE.md

@@ -25,6 +25,7 @@ the edge before prod. Each phase maps back to the owner's raw pre-release TODO l
 | R6 | Refactor + docs reconciliation + de-staging | 7 | **done** |
 | R7 | Final stress run + tuning | 9b | **done** |
 | UI | Tab-bar navigation redesign (drop the hamburger) | owner ad-hoc | **done** |
+| MW | "Multiple words per turn" rule for Russian games (engine v1.1.0) | owner ad-hoc | **done** |
 | → | Stage 18 — prod contour deploy | — | see [`PLAN.md`](PLAN.md) |
 
 ## Key findings (these reshaped the raw list — read before starting a phase)

backend/README.md

@@ -29,7 +29,8 @@ that auto-resigns overdue turns (honouring each player's daily away window). Lik
 the engine it is a service/store layer; the HTTP surface lives in the `gateway`.
 
 The lobby and social fabric. `internal/lobby` holds an in-memory
-matchmaking pool (FIFO per variant, pairs two humans into an auto-match) and
+matchmaking pool (FIFO per variant and per-turn word rule, pairs two humans into an
+auto-match) and
 friend-game invitations (invite → accept, starting a 2–4 player game once every
 invitee accepts). `internal/social` owns the friend graph (request/accept),
 per-user blocks, and per-game chat with nudges folded in as a message kind; chat

backend/go.mod

@@ -3,7 +3,7 @@ module scrabble/backend
 go 1.26.3
 
 require (
-	gitea.iliadenisov.ru/developer/scrabble-solver v1.0.0
+	gitea.iliadenisov.ru/developer/scrabble-solver v1.1.0
 	github.com/XSAM/otelsql v0.42.0
 	github.com/gin-gonic/gin v1.12.0
 	github.com/go-jet/jet/v2 v2.14.1

backend/internal/engine/game.go

@@ -92,6 +92,12 @@ type Options struct {
 	// DropoutTiles is the disposition of a dropped-out player's tiles in a game
 	// with three or more seats; the zero value removes them from play.
 	DropoutTiles DropoutTiles
+	// MultipleWordsPerTurn selects standard Scrabble when true: every cross-word a
+	// play forms must be a valid word and is scored. When false the game uses the
+	// "single word per turn" rule — only the main word is validated and scored and
+	// perpendicular cross-words are ignored. Callers always set this explicitly; the
+	// zero value (false) is the single-word rule.
+	MultipleWordsPerTurn bool
 }
 
 // Game is the in-memory state of a single match and the pure rules engine over
@@ -114,6 +120,7 @@ type Game struct {
 	reason        EndReason
 	resigned      []bool       // per seat; a resigned seat is skipped and cannot win
 	dropoutTiles  DropoutTiles // disposition of a resigned seat's tiles
+	multipleWords bool         // false = single-word rule (perpendicular cross-words ignored)
 	log           []MoveRecord
 }
 
@@ -150,6 +157,7 @@ func New(reg *Registry, opts Options) (*Game, error) {
 		scores:        make([]int, opts.Players),
 		resigned:      make([]bool, opts.Players),
 		dropoutTiles:  opts.DropoutTiles,
+		multipleWords: opts.MultipleWordsPerTurn,
 	}
 	for i := range g.hands {
 		g.hands[i] = g.bag.Draw(rs.RackSize)
@@ -157,6 +165,13 @@ func New(reg *Registry, opts Options) (*Game, error) {
 	return g, nil
 }
 
+// playOpts returns the solver play options for this game's rules. Under the single-word
+// rule (multipleWords false) the solver ignores perpendicular cross-words: only the main
+// word is validated and scored, and move generation is not constrained by cross-words.
+func (g *Game) playOpts() scrabble.PlayOptions {
+	return scrabble.PlayOptions{IgnoreCrossWords: !g.multipleWords}
+}
+
 // Play validates and applies the current player's placement of tiles forming a
 // word in direction dir. It scores the play, refills the rack from the bag,
 // advances the turn and may end the game. It returns ErrTilesNotOnRack when the
@@ -170,7 +185,7 @@ func (g *Game) Play(dir scrabble.Direction, tiles []scrabble.Placement) (MoveRec
 	if err := g.checkHolds(player, placementTiles(tiles)); err != nil {
 		return MoveRecord{}, err
 	}
-	move, err := g.solver.ValidatePlay(g.board, dir, tiles)
+	move, err := g.solver.ValidatePlayOpts(g.board, dir, tiles, g.playOpts())
 	if err != nil {
 		return MoveRecord{}, fmt.Errorf("%w: %v", ErrIllegalPlay, err)
 	}
@@ -279,7 +294,7 @@ func (g *Game) ResignSeat(seat int) (MoveRecord, error) {
 // GenerateMoves returns every legal play for the current player's rack, ranked
 // by descending score. It is empty when the player has no legal play.
 func (g *Game) GenerateMoves() []scrabble.Move {
-	return g.solver.GenerateMoves(g.board, g.rackOf(g.toMove), scrabble.Both)
+	return g.solver.GenerateMovesOpts(g.board, g.rackOf(g.toMove), scrabble.Both, g.playOpts())
 }
 
 // Hint returns the highest-scoring legal play for the current player and true,

backend/internal/engine/singleword_test.go

@@ -0,0 +1,48 @@
+package engine
+
+import "testing"
+
+// TestSingleWordRuleWiring confirms Options.MultipleWordsPerTurn reaches the solver. The
+// single-word game ignores perpendicular cross-words, so move generation from a shared
+// position is a superset of the standard game's; the standard game does not relax them.
+func TestSingleWordRuleWiring(t *testing.T) {
+	const seed = 7
+	mk := func(multipleWords bool) *Game {
+		g, err := New(testReg, Options{
+			Variant:              VariantEnglish,
+			Version:              testVersion,
+			Players:              2,
+			Seed:                 seed,
+			MultipleWordsPerTurn: multipleWords,
+		})
+		if err != nil {
+			t.Fatalf("new game: %v", err)
+		}
+		return g
+	}
+	std, single := mk(true), mk(false)
+	if std.playOpts().IgnoreCrossWords {
+		t.Error("standard game must not ignore cross-words")
+	}
+	if !single.playOpts().IgnoreCrossWords {
+		t.Error("single-word game must ignore cross-words")
+	}
+
+	// Play the same opening (the standard game's top move) in both games, then compare
+	// the next player's candidate moves. Both games share the seed, so the next rack is
+	// identical; relaxed (single-word) generation never drops a legal standard move.
+	hint, ok := std.HintView()
+	if !ok {
+		t.Fatal("opening game has no hint")
+	}
+	if _, err := std.SubmitPlay(hint.Tiles); err != nil {
+		t.Fatalf("standard opening: %v", err)
+	}
+	if _, err := single.SubmitPlay(hint.Tiles); err != nil {
+		t.Fatalf("single-word opening: %v", err)
+	}
+	stdMoves, singleMoves := len(std.GenerateMoves()), len(single.GenerateMoves())
+	if singleMoves < stdMoves {
+		t.Errorf("single-word generation produced %d moves, want >= standard %d", singleMoves, stdMoves)
+	}
+}

backend/internal/game/service.go

@@ -112,6 +112,7 @@ func (svc *Service) Create(ctx context.Context, params CreateParams) (Game, erro
 		Players:              len(params.Seats),
 		Seed:                 seed,
 		DropoutTiles:         params.DropoutTiles,
+		MultipleWordsPerTurn: params.MultipleWordsPerTurn,
 	})
 	if err != nil {
 		if errors.Is(err, engine.ErrUnknownVariant) || errors.Is(err, engine.ErrUnknownVersion) {
@@ -134,6 +135,7 @@ func (svc *Service) Create(ctx context.Context, params CreateParams) (Game, erro
 		hintsAllowed:         params.HintsAllowed,
 		hintsPerPlayer:       params.HintsPerPlayer,
 		dropoutTiles:         params.DropoutTiles.String(),
+		multipleWordsPerTurn: params.MultipleWordsPerTurn,
 	}
 	if err := svc.store.CreateGame(ctx, ins, params.Seats); err != nil {
 		return Game{}, err
@@ -939,6 +941,7 @@ func (svc *Service) replay(ctx context.Context, pre Game) (*engine.Game, error)
 		Players:              pre.Players,
 		Seed:                 seed,
 		DropoutTiles:         pre.DropoutTiles,
+		MultipleWordsPerTurn: pre.MultipleWordsPerTurn,
 	})
 	if err != nil {
 		return nil, err

backend/internal/game/store.go

@@ -38,6 +38,8 @@ type gameInsert struct {
 	hintsAllowed    bool
 	hintsPerPlayer  int
 	dropoutTiles    string
+	// multipleWordsPerTurn false selects the single-word rule for the game.
+	multipleWordsPerTurn bool
 }
 
 // statDelta is one account's contribution to its statistics on a game finish.
@@ -92,8 +94,8 @@ func (s *Store) CreateGame(ctx context.Context, ins gameInsert, seats []uuid.UUI
 		gi := table.Games.INSERT(
 			table.Games.GameID, table.Games.Variant, table.Games.DictVersion, table.Games.Seed,
 			table.Games.Players, table.Games.TurnTimeoutSecs, table.Games.HintsAllowed, table.Games.HintsPerPlayer,
-			table.Games.DropoutTiles,
+			table.Games.DropoutTiles, table.Games.MultipleWordsPerTurn,
-		).VALUES(ins.id, ins.variant, ins.dictVersion, ins.seed, ins.players, ins.turnTimeoutSecs, ins.hintsAllowed, ins.hintsPerPlayer, ins.dropoutTiles)
+		).VALUES(ins.id, ins.variant, ins.dictVersion, ins.seed, ins.players, ins.turnTimeoutSecs, ins.hintsAllowed, ins.hintsPerPlayer, ins.dropoutTiles, ins.multipleWordsPerTurn)
 		if _, err := gi.ExecContext(ctx, tx); err != nil {
 			return fmt.Errorf("insert game: %w", err)
 		}
@@ -761,6 +763,7 @@ func projectGame(g model.Games, seats []model.GamePlayers) (Game, error) {
 		CreatedAt:      g.CreatedAt,
 		UpdatedAt:      g.UpdatedAt,
 	}
+	out.MultipleWordsPerTurn = g.MultipleWordsPerTurn
 	if g.EndReason != nil {
 		out.EndReason = *g.EndReason
 	}

backend/internal/game/types.go

@@ -80,6 +80,9 @@ type CreateParams struct {
 	HintsPerPlayer int                 // starting per-seat hint allowance
 	DropoutTiles   engine.DropoutTiles // disposition of a dropped-out seat's tiles (3+ players); zero → remove
 	Seed           int64               // zero → a random seed is chosen
+	// MultipleWordsPerTurn true selects standard Scrabble; false the single-word rule —
+	// only the main word is validated and scored. Russian games default to false.
+	MultipleWordsPerTurn bool
 }
 
 // Game is the persisted state of a match: the games row joined with its seats.
@@ -101,6 +104,8 @@ type Game struct {
 	CreatedAt      time.Time
 	UpdatedAt      time.Time
 	FinishedAt     *time.Time
+	// MultipleWordsPerTurn true selects standard Scrabble; false the single-word rule.
+	MultipleWordsPerTurn bool
 }
 
 // Seat is one player's standing in a game.

backend/internal/inttest/lobby_test.go

@@ -35,14 +35,14 @@ func TestMatchmakingPairsAndStartsGame(t *testing.T) {
 	mm := newMatchmaker(t, newRobotService(t, newGameService()), 10*time.Second)
 	a, b := provisionAccount(t), provisionAccount(t)
 
-	r1, err := mm.Enqueue(ctx, a, engine.VariantEnglish)
+	r1, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true)
 	if err != nil {
 		t.Fatalf("enqueue a: %v", err)
 	}
 	if r1.Matched {
 		t.Fatal("first enqueue must wait")
 	}
-	r2, err := mm.Enqueue(ctx, b, engine.VariantEnglish)
+	r2, err := mm.Enqueue(ctx, b, engine.VariantEnglish, true)
 	if err != nil {
 		t.Fatalf("enqueue b: %v", err)
 	}

backend/internal/inttest/robot_test.go

@@ -150,7 +150,7 @@ func TestMatchmakerSubstitutesRobotEndToEnd(t *testing.T) {
 	human := provisionAccount(t)
 
 	before := time.Now()
-	r, err := mm.Enqueue(ctx, human, engine.VariantEnglish)
+	r, err := mm.Enqueue(ctx, human, engine.VariantEnglish, true)
 	if err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}

backend/internal/lobby/invitations.go

@@ -49,6 +49,8 @@ type InvitationSettings struct {
 	HintsAllowed   bool
 	HintsPerPlayer int
 	DropoutTiles   engine.DropoutTiles
+	// MultipleWordsPerTurn true selects standard Scrabble; false the single-word rule.
+	MultipleWordsPerTurn bool
 }
 
 // Invitee is one invited player's seat and response.
@@ -221,6 +223,7 @@ func (svc *InvitationService) CreateInvitation(ctx context.Context, inviterID uu
 		hintsAllowed:         settings.HintsAllowed,
 		hintsPerPlayer:       settings.HintsPerPlayer,
 		dropoutTiles:         settings.DropoutTiles.String(),
+		multipleWordsPerTurn: settings.MultipleWordsPerTurn,
 		expiresAt:            svc.now().Add(invitationTTL),
 	}
 	if err := svc.store.insertInvitation(ctx, ins, inviteeIDs); err != nil {
@@ -271,6 +274,7 @@ func (svc *InvitationService) startGame(ctx context.Context, invitationID uuid.U
 		HintsAllowed:         inv.Settings.HintsAllowed,
 		HintsPerPlayer:       inv.Settings.HintsPerPlayer,
 		DropoutTiles:         inv.Settings.DropoutTiles,
+		MultipleWordsPerTurn: inv.Settings.MultipleWordsPerTurn,
 	})
 	if err != nil {
 		return err
@@ -322,6 +326,8 @@ type invitationInsert struct {
 	hintsPerPlayer  int
 	dropoutTiles    string
 	expiresAt       time.Time
+	// multipleWordsPerTurn false selects the single-word rule.
+	multipleWordsPerTurn bool
 }
 
 // respondResult reports the state after an invitee response.
@@ -335,8 +341,8 @@ func (s *Store) insertInvitation(ctx context.Context, ins invitationInsert, invi
 		ii := table.GameInvitations.INSERT(
 			table.GameInvitations.InvitationID, table.GameInvitations.InviterID, table.GameInvitations.Variant,
 			table.GameInvitations.TurnTimeoutSecs, table.GameInvitations.HintsAllowed, table.GameInvitations.HintsPerPlayer,
-			table.GameInvitations.DropoutTiles, table.GameInvitations.ExpiresAt,
+			table.GameInvitations.DropoutTiles, table.GameInvitations.MultipleWordsPerTurn, table.GameInvitations.ExpiresAt,
-		).VALUES(ins.id, ins.inviterID, ins.variant, ins.turnTimeoutSecs, ins.hintsAllowed, ins.hintsPerPlayer, ins.dropoutTiles, ins.expiresAt)
+		).VALUES(ins.id, ins.inviterID, ins.variant, ins.turnTimeoutSecs, ins.hintsAllowed, ins.hintsPerPlayer, ins.dropoutTiles, ins.multipleWordsPerTurn, ins.expiresAt)
 		if _, err := ii.ExecContext(ctx, tx); err != nil {
 			return fmt.Errorf("insert invitation: %w", err)
 		}
@@ -382,6 +388,7 @@ func (s *Store) loadInvitation(ctx context.Context, id uuid.UUID) (Invitation, e
 			HintsAllowed:         row.HintsAllowed,
 			HintsPerPlayer:       int(row.HintsPerPlayer),
 			DropoutTiles:         dropout,
+			MultipleWordsPerTurn: row.MultipleWordsPerTurn,
 		},
 		Status:    row.Status,
 		GameID:    row.GameID,

backend/internal/lobby/matchmaker.go

@@ -14,6 +14,14 @@ import (
 	"scrabble/backend/internal/notify"
 )
 
+// matchKey buckets the auto-match pool: two players are paired only when they chose
+// the same variant and the same per-turn word rule (multipleWords), so a game always
+// starts under a rule both players asked for.
+type matchKey struct {
+	variant       engine.Variant
+	multipleWords bool
+}
+
 // Matchmaker is the in-memory auto-match pool: a FIFO queue per variant that pairs
 // the next two humans into a two-player game, or — when no human arrives within
 // the wait window — substitutes a robot. It holds no database state and is lost on
@@ -35,8 +43,8 @@ type Matchmaker struct {
 	log       *zap.Logger
 
 	mu           sync.Mutex
-	queues       map[engine.Variant][]uuid.UUID
+	queues       map[matchKey][]uuid.UUID
-	queued       map[uuid.UUID]engine.Variant
+	queued       map[uuid.UUID]matchKey
 	waitingSince map[uuid.UUID]time.Time
 	results      map[uuid.UUID]game.Game
 	rng          *rand.Rand
@@ -55,8 +63,8 @@ func NewMatchmaker(games GameCreator, robots RobotProvider, waitDelay time.Durat
 		clock:        func() time.Time { return time.Now().UTC() },
 		pub:          notify.Nop{},
 		log:          log,
-		queues:       make(map[engine.Variant][]uuid.UUID),
+		queues:       make(map[matchKey][]uuid.UUID),
-		queued:       make(map[uuid.UUID]engine.Variant),
+		queued:       make(map[uuid.UUID]matchKey),
 		waitingSince: make(map[uuid.UUID]time.Time),
 		results:      make(map[uuid.UUID]game.Game),
 		rng:          rand.New(rand.NewSource(time.Now().UnixNano())),
@@ -101,34 +109,36 @@ type EnqueueResult struct {
 	Game    game.Game
 }
 
-// Enqueue joins accountID to the variant pool. If an opponent already waits, the
+// Enqueue joins accountID to the auto-match pool for variant under the chosen
-// two are paired (seat order randomised for first-move fairness) and a game starts
+// per-turn word rule (multipleWords). If an opponent already waits for the same
-// immediately; otherwise the account waits, and a later pairing or robot
+// variant and rule, the two are paired (seat order randomised for first-move
-// substitution is delivered through Poll. An account already waiting in any pool
+// fairness) and a game starts immediately; otherwise the account waits, and a later
-// gets ErrAlreadyQueued.
+// pairing or robot substitution is delivered through Poll. An account already waiting
-func (m *Matchmaker) Enqueue(ctx context.Context, accountID uuid.UUID, variant engine.Variant) (EnqueueResult, error) {
+// in any pool gets ErrAlreadyQueued.
+func (m *Matchmaker) Enqueue(ctx context.Context, accountID uuid.UUID, variant engine.Variant, multipleWords bool) (EnqueueResult, error) {
+	key := matchKey{variant: variant, multipleWords: multipleWords}
 	m.mu.Lock()
 	if _, ok := m.queued[accountID]; ok {
 		m.mu.Unlock()
 		return EnqueueResult{}, ErrAlreadyQueued
 	}
-	q := m.queues[variant]
+	q := m.queues[key]
 	if len(q) == 0 {
-		m.queues[variant] = append(q, accountID)
+		m.queues[key] = append(q, accountID)
-		m.queued[accountID] = variant
+		m.queued[accountID] = key
 		m.waitingSince[accountID] = m.clock()
 		m.mu.Unlock()
 		return EnqueueResult{}, nil
 	}
 	opponent := q[0]
-	m.removeLocked(opponent, variant)
+	m.removeLocked(opponent, key)
 	seats := []uuid.UUID{opponent, accountID}
 	if m.rng.Intn(2) == 0 {
 		seats[0], seats[1] = seats[1], seats[0]
 	}
 	m.mu.Unlock()
 
-	g, err := m.games.Create(ctx, autoMatchParams(variant, seats))
+	g, err := m.games.Create(ctx, autoMatchParams(key, seats))
 	if err != nil {
 		return EnqueueResult{}, err
 	}
@@ -161,19 +171,21 @@ func (m *Matchmaker) Cancel(_ context.Context, accountID uuid.UUID) bool {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	delete(m.results, accountID)
-	variant, ok := m.queued[accountID]
+	key, ok := m.queued[accountID]
 	if !ok {
 		return false
 	}
-	m.removeLocked(accountID, variant)
+	m.removeLocked(accountID, key)
 	return true
 }
 
-// QueueLen returns the number of accounts waiting in the variant pool.
+// QueueLen returns the number of accounts waiting in the variant pool, summed across
+// both per-turn word rules.
 func (m *Matchmaker) QueueLen(variant engine.Variant) int {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	return len(m.queues[variant])
+	return len(m.queues[matchKey{variant: variant, multipleWords: false}]) +
+		len(m.queues[matchKey{variant: variant, multipleWords: true}])
 }
 
 // RunReaper substitutes a robot for any player that has waited past waitDelay,
@@ -199,7 +211,7 @@ func (m *Matchmaker) RunReaper(ctx context.Context, interval time.Duration) {
 func (m *Matchmaker) Reap(ctx context.Context, now time.Time) {
 	type sub struct {
 		human uuid.UUID
-		variant engine.Variant
+		key   matchKey
 		seats []uuid.UUID
 	}
 	m.mu.Lock()
@@ -211,23 +223,23 @@ func (m *Matchmaker) Reap(ctx context.Context, now time.Time) {
 	}
 	var subs []sub
 	for _, acc := range due {
-		variant := m.queued[acc]
+		key := m.queued[acc]
-		robotID, err := m.robots.Pick(variant)
+		robotID, err := m.robots.Pick(key.variant)
 		if err != nil {
 			m.log.Warn("robot substitution deferred", zap.Error(err))
 			continue
 		}
-		m.removeLocked(acc, variant)
+		m.removeLocked(acc, key)
 		seats := []uuid.UUID{acc, robotID}
 		if m.rng.Intn(2) == 0 {
 			seats[0], seats[1] = seats[1], seats[0]
 		}
-		subs = append(subs, sub{human: acc, variant: variant, seats: seats})
+		subs = append(subs, sub{human: acc, key: key, seats: seats})
 	}
 	m.mu.Unlock()
 
 	for _, s := range subs {
-		g, err := m.games.Create(ctx, autoMatchParams(s.variant, s.seats))
+		g, err := m.games.Create(ctx, autoMatchParams(s.key, s.seats))
 		if err != nil {
 			m.log.Warn("robot substitution failed", zap.String("human", s.human.String()), zap.Error(err))
 			continue
@@ -241,13 +253,13 @@ func (m *Matchmaker) Reap(ctx context.Context, now time.Time) {
 
 // removeLocked drops accountID from the queue, the queued index and the waiting
 // clock. The caller holds m.mu.
-func (m *Matchmaker) removeLocked(accountID uuid.UUID, variant engine.Variant) {
+func (m *Matchmaker) removeLocked(accountID uuid.UUID, key matchKey) {
 	delete(m.queued, accountID)
 	delete(m.waitingSince, accountID)
-	q := m.queues[variant]
+	q := m.queues[key]
 	for i, id := range q {
 		if id == accountID {
-			m.queues[variant] = append(q[:i], q[i+1:]...)
+			m.queues[key] = append(q[:i], q[i+1:]...)
 			break
 		}
 	}
@@ -255,12 +267,13 @@ func (m *Matchmaker) removeLocked(accountID uuid.UUID, variant engine.Variant) {
 
 // autoMatchParams builds the create parameters for a two-player auto-match with
 // the casual defaults.
-func autoMatchParams(variant engine.Variant, seats []uuid.UUID) game.CreateParams {
+func autoMatchParams(key matchKey, seats []uuid.UUID) game.CreateParams {
 	return game.CreateParams{
-		Variant:        variant,
+		Variant:              key.variant,
 		Seats:                seats,
 		TurnTimeout:          game.DefaultTurnTimeout,
 		HintsAllowed:         autoMatchHintsAllowed,
 		HintsPerPlayer:       autoMatchHintsPerPlayer,
+		MultipleWordsPerTurn: key.multipleWords,
 	}
 }

backend/internal/lobby/matchmaker_test.go

@@ -80,7 +80,7 @@ func TestMatchmakerPairsTwoHumans(t *testing.T) {
 	ctx := context.Background()
 	a, b := uuid.New(), uuid.New()
 
-	r1, err := mm.Enqueue(ctx, a, engine.VariantEnglish)
+	r1, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true)
 	if err != nil {
 		t.Fatalf("enqueue a: %v", err)
 	}
@@ -91,7 +91,7 @@ func TestMatchmakerPairsTwoHumans(t *testing.T) {
 		t.Fatalf("queue len = %d, want 1", mm.QueueLen(engine.VariantEnglish))
 	}
 
-	r2, err := mm.Enqueue(ctx, b, engine.VariantEnglish)
+	r2, err := mm.Enqueue(ctx, b, engine.VariantEnglish, true)
 	if err != nil {
 		t.Fatalf("enqueue b: %v", err)
 	}
@@ -129,10 +129,10 @@ func TestMatchmakerAlreadyQueued(t *testing.T) {
 	mm := newTestMatchmaker(&fakeCreator{}, uuid.New())
 	ctx := context.Background()
 	a := uuid.New()
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); !errors.Is(err, ErrAlreadyQueued) {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); !errors.Is(err, ErrAlreadyQueued) {
 		t.Fatalf("second enqueue err = %v, want ErrAlreadyQueued", err)
 	}
 }
@@ -141,7 +141,7 @@ func TestMatchmakerCancel(t *testing.T) {
 	mm := newTestMatchmaker(&fakeCreator{}, uuid.New())
 	ctx := context.Background()
 	a := uuid.New()
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
 	if !mm.Cancel(ctx, a) {
@@ -159,10 +159,10 @@ func TestMatchmakerVariantsAreSeparate(t *testing.T) {
 	creator := &fakeCreator{}
 	mm := newTestMatchmaker(creator, uuid.New())
 	ctx := context.Background()
-	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue en: %v", err)
 	}
-	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble); err != nil {
+	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble, true); err != nil {
 		t.Fatalf("enqueue ru: %v", err)
 	}
 	if len(creator.created) != 0 {
@@ -179,7 +179,7 @@ func TestMatchmakerFIFO(t *testing.T) {
 	ctx := context.Background()
 	a, b, c := uuid.New(), uuid.New(), uuid.New()
 	for _, id := range []uuid.UUID{a, b, c} {
-		if _, err := mm.Enqueue(ctx, id, engine.VariantEnglish); err != nil {
+		if _, err := mm.Enqueue(ctx, id, engine.VariantEnglish, true); err != nil {
 			t.Fatalf("enqueue %s: %v", id, err)
 		}
 	}
@@ -204,7 +204,7 @@ func TestMatchmakerReaperSubstitutesRobot(t *testing.T) {
 	ctx := context.Background()
 	a := uuid.New()
 
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
 
@@ -237,7 +237,7 @@ func TestMatchmakerReaperSkipsCancelled(t *testing.T) {
 	ctx := context.Background()
 	a := uuid.New()
 
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
 	mm.Cancel(ctx, a)
@@ -258,7 +258,7 @@ func TestMatchmakerCancelClearsPendingResult(t *testing.T) {
 	ctx := context.Background()
 	a := uuid.New()
 
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
 	mm.Reap(ctx, base.Add(testWaitDelay+time.Second)) // substitution stores a pending result
@@ -276,7 +276,7 @@ func TestMatchmakerReaperDefersWithoutRobot(t *testing.T) {
 	ctx := context.Background()
 	a := uuid.New()
 
-	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish); err != nil {
+	if _, err := mm.Enqueue(ctx, a, engine.VariantEnglish, true); err != nil {
 		t.Fatalf("enqueue: %v", err)
 	}
 	mm.Reap(ctx, base.Add(testWaitDelay+time.Second))
@@ -287,3 +287,57 @@ func TestMatchmakerReaperDefersWithoutRobot(t *testing.T) {
 		t.Errorf("waiter must stay queued when substitution is deferred; len %d", mm.QueueLen(engine.VariantEnglish))
 	}
 }
+
+// TestMatchmakerRulesAreSeparate confirms two players who chose the same variant but a
+// different per-turn word rule are not paired, and that the rule reaches the started game.
+func TestMatchmakerRulesAreSeparate(t *testing.T) {
+	creator := &fakeCreator{}
+	mm := newTestMatchmaker(creator, uuid.New())
+	ctx := context.Background()
+
+	// Same variant, opposite rules: they must not match.
+	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble, false); err != nil {
+		t.Fatalf("enqueue single-word: %v", err)
+	}
+	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble, true); err != nil {
+		t.Fatalf("enqueue standard: %v", err)
+	}
+	if len(creator.created) != 0 {
+		t.Fatalf("different rules must not match; created %d", len(creator.created))
+	}
+
+	// A second single-word player pairs with the first; the game carries the rule.
+	r, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble, false)
+	if err != nil {
+		t.Fatalf("enqueue single-word opponent: %v", err)
+	}
+	if !r.Matched {
+		t.Fatal("same variant and rule must match")
+	}
+	if len(creator.created) != 1 {
+		t.Fatalf("created %d games, want 1", len(creator.created))
+	}
+	if creator.created[0].MultipleWordsPerTurn {
+		t.Error("single-word match must create a game with MultipleWordsPerTurn=false")
+	}
+}
+
+// TestMatchmakerReaperKeepsRule confirms a robot substitution carries the waiter's rule.
+func TestMatchmakerReaperKeepsRule(t *testing.T) {
+	creator := &fakeCreator{}
+	mm := newTestMatchmaker(creator, uuid.New())
+	base := time.Now()
+	mm.clock = func() time.Time { return base }
+	ctx := context.Background()
+
+	if _, err := mm.Enqueue(ctx, uuid.New(), engine.VariantRussianScrabble, false); err != nil {
+		t.Fatalf("enqueue: %v", err)
+	}
+	mm.Reap(ctx, base.Add(testWaitDelay+time.Second))
+	if len(creator.created) != 1 {
+		t.Fatalf("created %d games, want 1", len(creator.created))
+	}
+	if creator.created[0].MultipleWordsPerTurn {
+		t.Error("robot substitution must keep the waiter's single-word rule")
+	}
+}

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

@@ -20,6 +20,7 @@ type GameInvitations struct {
 	HintsAllowed         bool
 	HintsPerPlayer       int16
 	DropoutTiles         string
+	MultipleWordsPerTurn bool
 	Status               string
 	GameID               *uuid.UUID
 	ExpiresAt            time.Time

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

@@ -30,4 +30,5 @@ type Games struct {
 	UpdatedAt            time.Time
 	FinishedAt           *time.Time
 	DropoutTiles         string
+	MultipleWordsPerTurn bool
 }

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

@@ -24,6 +24,7 @@ type gameInvitationsTable struct {
 	HintsAllowed         postgres.ColumnBool
 	HintsPerPlayer       postgres.ColumnInteger
 	DropoutTiles         postgres.ColumnString
+	MultipleWordsPerTurn postgres.ColumnBool
 	Status               postgres.ColumnString
 	GameID               postgres.ColumnString
 	ExpiresAt            postgres.ColumnTimestampz
@@ -77,14 +78,15 @@ func newGameInvitationsTableImpl(schemaName, tableName, alias string) gameInvita
 		HintsAllowedColumn         = postgres.BoolColumn("hints_allowed")
 		HintsPerPlayerColumn       = postgres.IntegerColumn("hints_per_player")
 		DropoutTilesColumn         = postgres.StringColumn("dropout_tiles")
+		MultipleWordsPerTurnColumn = postgres.BoolColumn("multiple_words_per_turn")
 		StatusColumn               = postgres.StringColumn("status")
 		GameIDColumn               = postgres.StringColumn("game_id")
 		ExpiresAtColumn            = postgres.TimestampzColumn("expires_at")
 		CreatedAtColumn            = postgres.TimestampzColumn("created_at")
 		UpdatedAtColumn            = postgres.TimestampzColumn("updated_at")
-		allColumns            = postgres.ColumnList{InvitationIDColumn, InviterIDColumn, VariantColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, StatusColumn, GameIDColumn, ExpiresAtColumn, CreatedAtColumn, UpdatedAtColumn}
+		allColumns                 = postgres.ColumnList{InvitationIDColumn, InviterIDColumn, VariantColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn, StatusColumn, GameIDColumn, ExpiresAtColumn, CreatedAtColumn, UpdatedAtColumn}
-		mutableColumns        = postgres.ColumnList{InviterIDColumn, VariantColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, StatusColumn, GameIDColumn, ExpiresAtColumn, CreatedAtColumn, UpdatedAtColumn}
+		mutableColumns             = postgres.ColumnList{InviterIDColumn, VariantColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn, StatusColumn, GameIDColumn, ExpiresAtColumn, CreatedAtColumn, UpdatedAtColumn}
-		defaultColumns        = postgres.ColumnList{HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, StatusColumn, CreatedAtColumn, UpdatedAtColumn}
+		defaultColumns             = postgres.ColumnList{HintsAllowedColumn, HintsPerPlayerColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn, StatusColumn, CreatedAtColumn, UpdatedAtColumn}
 	)
 
 	return gameInvitationsTable{
@@ -98,6 +100,7 @@ func newGameInvitationsTableImpl(schemaName, tableName, alias string) gameInvita
 		HintsAllowed:         HintsAllowedColumn,
 		HintsPerPlayer:       HintsPerPlayerColumn,
 		DropoutTiles:         DropoutTilesColumn,
+		MultipleWordsPerTurn: MultipleWordsPerTurnColumn,
 		Status:               StatusColumn,
 		GameID:               GameIDColumn,
 		ExpiresAt:            ExpiresAtColumn,

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

@@ -34,6 +34,7 @@ type gamesTable struct {
 	UpdatedAt            postgres.ColumnTimestampz
 	FinishedAt           postgres.ColumnTimestampz
 	DropoutTiles         postgres.ColumnString
+	MultipleWordsPerTurn postgres.ColumnBool
 
 	AllColumns     postgres.ColumnList
 	MutableColumns postgres.ColumnList
@@ -92,9 +93,10 @@ func newGamesTableImpl(schemaName, tableName, alias string) gamesTable {
 		UpdatedAtColumn            = postgres.TimestampzColumn("updated_at")
 		FinishedAtColumn           = postgres.TimestampzColumn("finished_at")
 		DropoutTilesColumn         = postgres.StringColumn("dropout_tiles")
-		allColumns            = postgres.ColumnList{GameIDColumn, VariantColumn, DictVersionColumn, SeedColumn, StatusColumn, PlayersColumn, ToMoveColumn, TurnStartedAtColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, EndReasonColumn, CreatedAtColumn, UpdatedAtColumn, FinishedAtColumn, DropoutTilesColumn}
+		MultipleWordsPerTurnColumn = postgres.BoolColumn("multiple_words_per_turn")
-		mutableColumns        = postgres.ColumnList{VariantColumn, DictVersionColumn, SeedColumn, StatusColumn, PlayersColumn, ToMoveColumn, TurnStartedAtColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, EndReasonColumn, CreatedAtColumn, UpdatedAtColumn, FinishedAtColumn, DropoutTilesColumn}
+		allColumns                 = postgres.ColumnList{GameIDColumn, VariantColumn, DictVersionColumn, SeedColumn, StatusColumn, PlayersColumn, ToMoveColumn, TurnStartedAtColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, EndReasonColumn, CreatedAtColumn, UpdatedAtColumn, FinishedAtColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn}
-		defaultColumns        = postgres.ColumnList{StatusColumn, ToMoveColumn, TurnStartedAtColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, CreatedAtColumn, UpdatedAtColumn, DropoutTilesColumn}
+		mutableColumns             = postgres.ColumnList{VariantColumn, DictVersionColumn, SeedColumn, StatusColumn, PlayersColumn, ToMoveColumn, TurnStartedAtColumn, TurnTimeoutSecsColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, EndReasonColumn, CreatedAtColumn, UpdatedAtColumn, FinishedAtColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn}
+		defaultColumns             = postgres.ColumnList{StatusColumn, ToMoveColumn, TurnStartedAtColumn, HintsAllowedColumn, HintsPerPlayerColumn, MoveCountColumn, CreatedAtColumn, UpdatedAtColumn, DropoutTilesColumn, MultipleWordsPerTurnColumn}
 	)
 
 	return gamesTable{
@@ -118,6 +120,7 @@ func newGamesTableImpl(schemaName, tableName, alias string) gamesTable {
 		UpdatedAt:            UpdatedAtColumn,
 		FinishedAt:           FinishedAtColumn,
 		DropoutTiles:         DropoutTilesColumn,
+		MultipleWordsPerTurn: MultipleWordsPerTurnColumn,
 
 		AllColumns:     allColumns,
 		MutableColumns: mutableColumns,

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

@@ -97,6 +97,7 @@ CREATE TABLE games (
     updated_at        timestamptz NOT NULL DEFAULT now(),
     finished_at       timestamptz,
     dropout_tiles     text        NOT NULL DEFAULT 'remove',
+    multiple_words_per_turn boolean NOT NULL DEFAULT true,
     CONSTRAINT games_variant_chk CHECK (variant IN ('scrabble_en', 'scrabble_ru', 'erudit_ru')),
     CONSTRAINT games_status_chk CHECK (status IN ('active', 'finished')),
     CONSTRAINT games_players_chk CHECK (players BETWEEN 2 AND 4),
@@ -260,6 +261,7 @@ CREATE TABLE game_invitations (
     hints_allowed     boolean     NOT NULL DEFAULT true,
     hints_per_player  smallint    NOT NULL DEFAULT 1,
     dropout_tiles     text        NOT NULL DEFAULT 'remove',
+    multiple_words_per_turn boolean NOT NULL DEFAULT true,
     status            text        NOT NULL DEFAULT 'pending',
     game_id           uuid        REFERENCES games (game_id) ON DELETE SET NULL,
     expires_at        timestamptz NOT NULL,

backend/internal/server/handlers_invitations.go

@@ -35,6 +35,7 @@ type invitationDTO struct {
 	HintsAllowed         bool                   `json:"hints_allowed"`
 	HintsPerPlayer       int                    `json:"hints_per_player"`
 	DropoutTiles         string                 `json:"dropout_tiles"`
+	MultipleWordsPerTurn bool                   `json:"multiple_words_per_turn"`
 	Status               string                 `json:"status"`
 	GameID               string                 `json:"game_id,omitempty"`
 	ExpiresAtUnix        int64                  `json:"expires_at_unix"`
@@ -53,6 +54,7 @@ type createInvitationRequest struct {
 	HintsAllowed         bool     `json:"hints_allowed"`
 	HintsPerPlayer       int      `json:"hints_per_player"`
 	DropoutTiles         string   `json:"dropout_tiles"`
+	MultipleWordsPerTurn bool     `json:"multiple_words_per_turn"`
 }
 
 // invitationDTOFrom projects a lobby invitation, resolving names through memo.
@@ -66,6 +68,7 @@ func (s *Server) invitationDTOFrom(ctx context.Context, inv lobby.Invitation, me
 		HintsAllowed:         inv.Settings.HintsAllowed,
 		HintsPerPlayer:       inv.Settings.HintsPerPlayer,
 		DropoutTiles:         inv.Settings.DropoutTiles.String(),
+		MultipleWordsPerTurn: inv.Settings.MultipleWordsPerTurn,
 		Status:               inv.Status,
 		ExpiresAtUnix:        inv.ExpiresAt.Unix(),
 	}
@@ -105,6 +108,7 @@ func (s *Server) handleCreateInvitation(c *gin.Context) {
 		Variant:              variant,
 		HintsAllowed:         req.HintsAllowed,
 		HintsPerPlayer:       req.HintsPerPlayer,
+		MultipleWordsPerTurn: req.MultipleWordsPerTurn,
 	}
 	if req.TurnTimeoutSecs > 0 {
 		settings.TurnTimeout = time.Duration(req.TurnTimeoutSecs) * time.Second

backend/internal/server/handlers_user.go

@@ -133,9 +133,10 @@ func (s *Server) handleGameState(c *gin.Context) {
 	c.JSON(http.StatusOK, dto)
 }
 
-// enqueueRequest joins the per-variant auto-match pool.
+// enqueueRequest joins the per-variant auto-match pool under a per-turn word rule.
 type enqueueRequest struct {
 	Variant              string `json:"variant"`
+	MultipleWordsPerTurn bool   `json:"multiple_words_per_turn"`
 }
 
 // handleEnqueue joins the auto-match pool for a variant.
@@ -155,7 +156,7 @@ func (s *Server) handleEnqueue(c *gin.Context) {
 		abortBadRequest(c, "unknown variant")
 		return
 	}
-	res, err := s.matchmaker.Enqueue(c.Request.Context(), uid, variant)
+	res, err := s.matchmaker.Enqueue(c.Request.Context(), uid, variant, req.MultipleWordsPerTurn)
 	if err != nil {
 		s.abortErr(c, err)
 		return

docs/ARCHITECTURE.md

@@ -282,6 +282,17 @@ Key points:
 
 - **Word legality: validate-at-submit.** An illegal play is rejected by
   `Solver.ValidatePlay`; there is no challenge phase.
+- **Multiple words per turn (Russian games).** Russian variants carry a per-game
+  **single-word rule**, chosen on New Game (default **off** = single word; on = standard
+  Scrabble). Off, only the **main word** along the play direction is validated and scored —
+  perpendicular cross-words are ignored, including in robot move generation; on, every
+  cross-word must be a real word and is scored. The engine threads it as
+  `scrabble.PlayOptions{IgnoreCrossWords}` (solver `v1.1.0`); connectivity and the
+  first-move centre rule are unaffected. The "Russian-only" limit is a **UI affordance**:
+  the backend and engine are variant-agnostic about the flag, and English games always send
+  it on (standard). For auto-match the rule is part of the matchmaking key, so only players
+  who chose the same rule are paired (the rule field rides every create/enqueue request, so
+  matchmaking stays one uniform path).
 - **End of game**: the bag is empty **and** a player empties their rack, **or**
   **6 consecutive scoreless turns** (passes/exchanges), **or** a resignation, or
   a missed turn. The **per-game turn timeout** is chosen at creation

docs/FUNCTIONAL.md

@@ -85,7 +85,12 @@ unrestricted). Variants are shown by their **display name** — both Scrabble va
 the same name titles the in-game screen. This gates only **starting** a new game — both auto-match and a friend
 invitation — so a player still sees and plays existing games of any language. Auto-match
 (always 2 players) joins a per-variant pool and is paired with the next waiting human;
-after 10 s with no human the robot substitutes. Friend games (2–4) are
+after 10 s with no human the robot substitutes. For Russian games (auto-match or friend
+invitation), New Game also offers **"Multiple words per turn"** (default **off**): off plays
+the simplified **single-word rule** — only the word laid along the player's line must be a
+real word, and any incidental perpendicular words are ignored and not scored — while on is
+standard Scrabble. English games are always standard and show no such toggle. In auto-match
+the choice joins the pairing key, so a player only meets opponents who picked the same rule. Friend games (2–4) are
 formed by inviting players from the friend list (an invitation, like a friend code,
 is shareable as a Telegram deep link that opens it directly): the inviter chooses the
 settings and the game starts once every invitee has accepted — any decline cancels it, and an unanswered invitation

docs/FUNCTIONAL_ru.md

@@ -89,7 +89,13 @@ nudge) приходят от бота **этой партии** — по язы
 приглашение друга, — поэтому игрок по-прежнему видит и играет существующие игры на
 любом языке. Авто-подбор (всегда 2 игрока)
 встаёт в пул по варианту и сводится со следующим ожидающим человеком; через 10 с
-без человека подставляется робот. Игры с друзьями (2–4)
+без человека подставляется робот. Для русских игр (авто-подбор или приглашение) на экране
+новой игры есть опция **«Несколько слов за ход»** (по умолчанию **выключена**): выключена —
+упрощённое **правило одного слова**: настоящим словом должно быть только слово, выложенное
+вдоль линии хода, а случайные перпендикулярные слова игнорируются и не засчитываются;
+включена — обычный скрэббл. Английские игры всегда по стандартным правилам и тоггл не
+показывают. В авто-подборе выбор входит в ключ подбора, поэтому игрок сводится только с теми,
+кто выбрал то же правило. Игры с друзьями (2–4)
 формируются приглашением игроков из списка друзей (приглашение, как и код друга,
 можно отправить deep-link'ом в Telegram, который откроет его сразу): инициатор
 выбирает настройки, и партия стартует, когда приняли все приглашённые — любой отказ отменяет приглашение, а без

docs/UI_DESIGN.md

@@ -182,7 +182,9 @@ IV 🏅; active games show Your move 🟢 / Opponent's move ⏳; invitations use
 - **Invitations**: a lobby **section** (a 💌 row per open invitation) with Accept /
   Decline for an invitee and a waiting/Cancel state for the inviter; creating one is the
   **"Play with friends"** mode in `NewGame.svelte` (pick invitees, then variant / move
-  time / hints).
+  time / hints). For a **Russian** variant (auto-match or invite) a **"Multiple words per
+  turn"** checkbox (`.toggle`, **default off** = the single-word rule) appears; English
+  variants never show it.
 - **Statistics** (`screens/Stats.svelte`, the lobby 📊 tab): a 2-column grid of stat
   cards (wins / losses / draws / games / win-rate / best game / best move) — pure
   numbers, no charts.

gateway/internal/backendclient/api.go

@@ -245,11 +245,12 @@ func (c *Client) GameState(ctx context.Context, userID, gameID string, includeAl
 	return out, err
 }
 
-// Enqueue joins the auto-match pool for a variant.
+// Enqueue joins the auto-match pool for a variant under a per-turn word rule
-func (c *Client) Enqueue(ctx context.Context, userID, variant string) (MatchResp, error) {
+// (multipleWords true is standard Scrabble, false the single-word rule).
+func (c *Client) Enqueue(ctx context.Context, userID, variant string, multipleWords bool) (MatchResp, error) {
 	var out MatchResp
 	err := c.do(ctx, http.MethodPost, "/api/v1/user/lobby/enqueue", userID, "",
-		map[string]string{"variant": variant}, &out)
+		map[string]any{"variant": variant, "multiple_words_per_turn": multipleWords}, &out)
 	return out, err
 }
 

gateway/internal/backendclient/api_social.go

@@ -99,6 +99,8 @@ type InvitationParams struct {
 	HintsAllowed    bool
 	HintsPerPlayer  int
 	DropoutTiles    string
+	// MultipleWordsPerTurn true is standard Scrabble; false the single-word rule.
+	MultipleWordsPerTurn bool
 }
 
 // --- friends ---
@@ -195,6 +197,8 @@ func (c *Client) CreateInvitation(ctx context.Context, userID string, p Invitati
 		"hints_allowed":     p.HintsAllowed,
 		"hints_per_player":  p.HintsPerPlayer,
 		"dropout_tiles":     p.DropoutTiles,
+
+		"multiple_words_per_turn": p.MultipleWordsPerTurn,
 	}
 	err := c.do(ctx, http.MethodPost, "/api/v1/user/invitations", userID, "", body, &out)
 	return out, err

gateway/internal/transcode/transcode.go

@@ -224,7 +224,7 @@ func gameStateHandler(backend *backendclient.Client) Handler {
 func enqueueHandler(backend *backendclient.Client) Handler {
 	return func(ctx context.Context, req Request) ([]byte, error) {
 		in := fb.GetRootAsEnqueueRequest(req.Payload, 0)
-		m, err := backend.Enqueue(ctx, req.UserID, string(in.Variant()))
+		m, err := backend.Enqueue(ctx, req.UserID, string(in.Variant()), in.MultipleWordsPerTurn())
 		if err != nil {
 			return nil, err
 		}

gateway/internal/transcode/transcode_social.go

@@ -205,6 +205,8 @@ func invitationCreateHandler(backend *backendclient.Client) Handler {
 			HintsAllowed:    in.HintsAllowed(),
 			HintsPerPlayer:  int(in.HintsPerPlayer()),
 			DropoutTiles:    string(in.DropoutTiles()),
+
+			MultipleWordsPerTurn: in.MultipleWordsPerTurn(),
 		}
 		res, err := backend.CreateInvitation(ctx, req.UserID, params)
 		if err != nil {

go.work.sum

@@ -6,6 +6,8 @@ filippo.io/edwards25519 v1.2.0 h1:crnVqOiS4jqYleHd9vaKZ+HKtHfllngJIiOpNpoJsjo=
 filippo.io/edwards25519 v1.2.0/go.mod h1:xzAOLCNug/yB62zG1bQ8uziwrIqIuxhctzJT18Q77mc=
 gitea.iliadenisov.ru/developer/scrabble-solver v1.0.0 h1:ntN6m4cOB+4FelleO2nkAIZp8WSc+v25neetzfdUuuw=
 gitea.iliadenisov.ru/developer/scrabble-solver v1.0.0/go.mod h1:G60OiGZtkrRyYX8P3SSsjVpU707fufmZkvCkNFPFWrY=
+gitea.iliadenisov.ru/developer/scrabble-solver v1.1.0 h1:92jWbAZ5IK3ROrn1g3FjY0wZjeYpVWOJsl/GGT5HN1U=
+gitea.iliadenisov.ru/developer/scrabble-solver v1.1.0/go.mod h1:G60OiGZtkrRyYX8P3SSsjVpU707fufmZkvCkNFPFWrY=
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/ClickHouse/ch-go v0.71.0 h1:bUdZ/EZj/LcVHsMqaRUP2holqygrPWQKeMjc6nZoyRM=
 github.com/ClickHouse/ch-go v0.71.0/go.mod h1:NwbNc+7jaqfY58dmdDUbG4Jl22vThgx1cYjBw0vtgXw=

loadtest/go.mod

@@ -4,7 +4,7 @@ go 1.26.3
 
 require (
 	connectrpc.com/connect v1.19.2
-	gitea.iliadenisov.ru/developer/scrabble-solver v1.0.0
+	gitea.iliadenisov.ru/developer/scrabble-solver v1.1.0
 	github.com/google/flatbuffers v23.5.26+incompatible
 	github.com/google/uuid v1.6.0
 	github.com/iliadenisov/dafsa v1.1.0

pkg/fbs/scrabble.fbs

@@ -272,9 +272,11 @@ table GameList {
 
 // --- lobby (authenticated) ---
 
-// EnqueueRequest joins the per-variant auto-match pool.
+// EnqueueRequest joins the auto-match pool for a variant under a per-turn word rule.
+// multiple_words_per_turn true is standard Scrabble; false is the single-word rule.
 table EnqueueRequest {
   variant:string;
+  multiple_words_per_turn:bool;
 }
 
 // MatchResult reports whether the caller has been paired into a game yet.
@@ -457,6 +459,7 @@ table CreateInvitationRequest {
   hints_allowed:bool;
   hints_per_player:int;
   dropout_tiles:string;
+  multiple_words_per_turn:bool;
 }
 
 // InvitationActionRequest accepts / declines / cancels an invitation by id.

pkg/fbs/scrabblefb/CreateInvitationRequest.go

@@ -110,8 +110,20 @@ func (rcv *CreateInvitationRequest) DropoutTiles() []byte {
 	return nil
 }
 
+func (rcv *CreateInvitationRequest) MultipleWordsPerTurn() bool {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(16))
+	if o != 0 {
+		return rcv._tab.GetBool(o + rcv._tab.Pos)
+	}
+	return false
+}
+
+func (rcv *CreateInvitationRequest) MutateMultipleWordsPerTurn(n bool) bool {
+	return rcv._tab.MutateBoolSlot(16, n)
+}
+
 func CreateInvitationRequestStart(builder *flatbuffers.Builder) {
-	builder.StartObject(6)
+	builder.StartObject(7)
 }
 func CreateInvitationRequestAddInviteeIds(builder *flatbuffers.Builder, inviteeIds flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(inviteeIds), 0)
@@ -134,6 +146,9 @@ func CreateInvitationRequestAddHintsPerPlayer(builder *flatbuffers.Builder, hint
 func CreateInvitationRequestAddDropoutTiles(builder *flatbuffers.Builder, dropoutTiles flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(5, flatbuffers.UOffsetT(dropoutTiles), 0)
 }
+func CreateInvitationRequestAddMultipleWordsPerTurn(builder *flatbuffers.Builder, multipleWordsPerTurn bool) {
+	builder.PrependBoolSlot(6, multipleWordsPerTurn, false)
+}
 func CreateInvitationRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
 	return builder.EndObject()
 }

pkg/fbs/scrabblefb/EnqueueRequest.go

@@ -49,12 +49,27 @@ func (rcv *EnqueueRequest) Variant() []byte {
 	return nil
 }
 
+func (rcv *EnqueueRequest) MultipleWordsPerTurn() bool {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.GetBool(o + rcv._tab.Pos)
+	}
+	return false
+}
+
+func (rcv *EnqueueRequest) MutateMultipleWordsPerTurn(n bool) bool {
+	return rcv._tab.MutateBoolSlot(6, n)
+}
+
 func EnqueueRequestStart(builder *flatbuffers.Builder) {
-	builder.StartObject(1)
+	builder.StartObject(2)
 }
 func EnqueueRequestAddVariant(builder *flatbuffers.Builder, variant flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(variant), 0)
 }
+func EnqueueRequestAddMultipleWordsPerTurn(builder *flatbuffers.Builder, multipleWordsPerTurn bool) {
+	builder.PrependBoolSlot(1, multipleWordsPerTurn, false)
+}
 func EnqueueRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
 	return builder.EndObject()
 }

ui/e2e/game.spec.ts

@@ -70,6 +70,18 @@ test('new game: variant buttons show a rules summary and the move-limit', async
   await expect(page.locator('.movelimit')).toBeVisible(); // turn-time under the buttons
 });
 
+test('new game: Russian games offer the "multiple words per turn" toggle, off by default', async ({ page }) => {
+  await page.goto('/');
+  await page.getByRole('button', { name: /guest/i }).click();
+  await page.getByRole('button', { name: /New/ }).click(); // auto-match
+  // The mock session supports Russian, so the single-word-rule toggle is offered and starts off.
+  const toggle = page.getByLabel('Multiple words per turn');
+  await expect(toggle).toBeVisible();
+  await expect(toggle).not.toBeChecked();
+  await toggle.check();
+  await expect(toggle).toBeChecked();
+});
+
 test('a pending tile recalls on double-tap, not on a single tap', async ({ page }) => {
   await openGame(page);
   await page.locator('.rack .tile').first().click();

ui/src/gen/fbs/scrabblefb/create-invitation-request.ts

@@ -61,8 +61,13 @@ dropoutTiles(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
+multipleWordsPerTurn():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 static startCreateInvitationRequest(builder:flatbuffers.Builder) {
-  builder.startObject(6);
+  builder.startObject(7);
 }
 
 static addInviteeIds(builder:flatbuffers.Builder, inviteeIdsOffset:flatbuffers.Offset) {
@@ -101,12 +106,16 @@ static addDropoutTiles(builder:flatbuffers.Builder, dropoutTilesOffset:flatbuffe
   builder.addFieldOffset(5, dropoutTilesOffset, 0);
 }
 
+static addMultipleWordsPerTurn(builder:flatbuffers.Builder, multipleWordsPerTurn:boolean) {
+  builder.addFieldInt8(6, +multipleWordsPerTurn, +false);
+}
+
 static endCreateInvitationRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createCreateInvitationRequest(builder:flatbuffers.Builder, inviteeIdsOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, turnTimeoutSecs:number, hintsAllowed:boolean, hintsPerPlayer:number, dropoutTilesOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createCreateInvitationRequest(builder:flatbuffers.Builder, inviteeIdsOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, turnTimeoutSecs:number, hintsAllowed:boolean, hintsPerPlayer:number, dropoutTilesOffset:flatbuffers.Offset, multipleWordsPerTurn:boolean):flatbuffers.Offset {
   CreateInvitationRequest.startCreateInvitationRequest(builder);
   CreateInvitationRequest.addInviteeIds(builder, inviteeIdsOffset);
   CreateInvitationRequest.addVariant(builder, variantOffset);
@@ -114,6 +123,7 @@ static createCreateInvitationRequest(builder:flatbuffers.Builder, inviteeIdsOffs
   CreateInvitationRequest.addHintsAllowed(builder, hintsAllowed);
   CreateInvitationRequest.addHintsPerPlayer(builder, hintsPerPlayer);
   CreateInvitationRequest.addDropoutTiles(builder, dropoutTilesOffset);
+  CreateInvitationRequest.addMultipleWordsPerTurn(builder, multipleWordsPerTurn);
   return CreateInvitationRequest.endCreateInvitationRequest(builder);
 }
 }

ui/src/gen/fbs/scrabblefb/enqueue-request.ts

@@ -27,22 +27,32 @@ variant(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
+multipleWordsPerTurn():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 static startEnqueueRequest(builder:flatbuffers.Builder) {
-  builder.startObject(1);
+  builder.startObject(2);
 }
 
 static addVariant(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset) {
   builder.addFieldOffset(0, variantOffset, 0);
 }
 
+static addMultipleWordsPerTurn(builder:flatbuffers.Builder, multipleWordsPerTurn:boolean) {
+  builder.addFieldInt8(1, +multipleWordsPerTurn, +false);
+}
+
 static endEnqueueRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createEnqueueRequest(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createEnqueueRequest(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset, multipleWordsPerTurn:boolean):flatbuffers.Offset {
   EnqueueRequest.startEnqueueRequest(builder);
   EnqueueRequest.addVariant(builder, variantOffset);
+  EnqueueRequest.addMultipleWordsPerTurn(builder, multipleWordsPerTurn);
   return EnqueueRequest.endEnqueueRequest(builder);
 }
 }

ui/src/lib/client.ts

@@ -63,7 +63,7 @@ export interface GatewayClient {
   gamesList(): Promise<GameList>;
 
   // --- lobby ---
-  lobbyEnqueue(variant: Variant): Promise<MatchResult>;
+  lobbyEnqueue(variant: Variant, multipleWords: boolean): Promise<MatchResult>;
   lobbyPoll(): Promise<MatchResult>;
   /** Leave the auto-match pool (idempotent); a cancelled quick-match must not stay queued. */
   lobbyCancel(): Promise<void>;

ui/src/lib/codec.ts

@@ -149,11 +149,12 @@ export function encodeComplaint(gameId: string, word: string, note: string): Uin
   return finish(b, fb.ComplaintRequest.endComplaintRequest(b));
 }
 
-export function encodeEnqueue(variant: Variant): Uint8Array {
+export function encodeEnqueue(variant: Variant, multipleWords: boolean): Uint8Array {
   const b = new Builder(64);
   const v = b.createString(variant);
   fb.EnqueueRequest.startEnqueueRequest(b);
   fb.EnqueueRequest.addVariant(b, v);
+  fb.EnqueueRequest.addMultipleWordsPerTurn(b, multipleWords);
   return finish(b, fb.EnqueueRequest.endEnqueueRequest(b));
 }
 
@@ -523,6 +524,7 @@ export function encodeCreateInvitation(inviteeIds: string[], st: InvitationSetti
   fb.CreateInvitationRequest.addHintsAllowed(b, st.hintsAllowed);
   fb.CreateInvitationRequest.addHintsPerPlayer(b, st.hintsPerPlayer);
   fb.CreateInvitationRequest.addDropoutTiles(b, dropout);
+  fb.CreateInvitationRequest.addMultipleWordsPerTurn(b, st.multipleWordsPerTurn);
   return finish(b, fb.CreateInvitationRequest.endCreateInvitationRequest(b));
 }
 

ui/src/lib/i18n/en.ts

@@ -232,6 +232,7 @@ export const en = {
   'new.invite': 'Send invitation',
   'new.moveTime': 'Move time',
   'new.hintsPerPlayer': 'Hints per player',
+  'new.multipleWordsPerTurn': 'Multiple words per turn',
   'new.invited': 'Invitation sent.',
   'new.noFriends': 'Add friends first to invite them.',
 

ui/src/lib/i18n/ru.ts

@@ -233,6 +233,7 @@ export const ru: Record<MessageKey, string> = {
   'new.invite': 'Отправить приглашение',
   'new.moveTime': 'Время на ход',
   'new.hintsPerPlayer': 'Подсказок на игрока',
+  'new.multipleWordsPerTurn': 'Несколько слов за ход',
   'new.invited': 'Приглашение отправлено.',
   'new.noFriends': 'Сначала добавьте друзей, чтобы пригласить их.',
 

ui/src/lib/mock/client.ts

@@ -142,7 +142,7 @@ export class MockGateway implements GatewayClient {
   }
 
   // --- lobby ---
-  async lobbyEnqueue(variant: Variant): Promise<MatchResult> {
+  async lobbyEnqueue(variant: Variant, _multipleWords: boolean): Promise<MatchResult> {
     // Simulate a 10s-style robot substitution, sped up: match found shortly.
     const id = crypto.randomUUID();
     const g: MockGame = {

ui/src/lib/model.ts

@@ -158,6 +158,8 @@ export interface InvitationSettings {
   hintsAllowed: boolean;
   hintsPerPlayer: number;
   dropoutTiles: 'remove' | 'return';
+  /** true = standard Scrabble; false = the single-word rule (Russian games). */
+  multipleWordsPerTurn: boolean;
 }
 
 export interface InvitationInvitee {

ui/src/lib/transport.ts

@@ -81,8 +81,8 @@ export function createTransport(baseUrl: string): GatewayClient {
       return codec.decodeGameList(await exec('games.list', codec.empty()));
     },
 
-    async lobbyEnqueue(variant) {
+    async lobbyEnqueue(variant, multipleWords) {
-      return codec.decodeMatchResult(await exec('lobby.enqueue', codec.encodeEnqueue(variant)));
+      return codec.decodeMatchResult(await exec('lobby.enqueue', codec.encodeEnqueue(variant, multipleWords)));
     },
     async lobbyPoll() {
       return codec.decodeMatchResult(await exec('lobby.poll', codec.empty()));

ui/src/lib/variants.test.ts

@@ -1,6 +1,11 @@
 import { describe, it, expect } from 'vitest';
 
-import { ALL_VARIANTS, availableVariants } from './variants';
+import {
+  ALL_VARIANTS,
+  availableVariants,
+  supportsMultipleWordsToggle,
+  multipleWordsForRequest,
+} from './variants';
 
 describe('availableVariants', () => {
   it('is ungated (all variants) for an empty or absent set', () => {
@@ -20,3 +25,24 @@ describe('availableVariants', () => {
     expect(availableVariants(['en', 'ru']).map((v) => v.id)).toEqual(['scrabble_en', 'scrabble_ru', 'erudit_ru']);
   });
 });
+
+describe('supportsMultipleWordsToggle', () => {
+  it('is true for Russian variants only', () => {
+    expect(supportsMultipleWordsToggle('scrabble_ru')).toBe(true);
+    expect(supportsMultipleWordsToggle('erudit_ru')).toBe(true);
+    expect(supportsMultipleWordsToggle('scrabble_en')).toBe(false);
+  });
+});
+
+describe('multipleWordsForRequest', () => {
+  it('carries the toggle for Russian games', () => {
+    expect(multipleWordsForRequest('scrabble_ru', false)).toBe(false);
+    expect(multipleWordsForRequest('scrabble_ru', true)).toBe(true);
+    expect(multipleWordsForRequest('erudit_ru', false)).toBe(false);
+  });
+
+  it('forces standard (true) for English whatever the toggle', () => {
+    expect(multipleWordsForRequest('scrabble_en', false)).toBe(true);
+    expect(multipleWordsForRequest('scrabble_en', true)).toBe(true);
+  });
+});

ui/src/lib/variants.ts

@@ -55,3 +55,17 @@ export function availableVariants(supportedLanguages: string[] | undefined): Var
   if (langs.length === 0) return ALL_VARIANTS;
   return ALL_VARIANTS.filter((v) => langs.includes(VARIANT_LANGUAGE[v.id]));
 }
+
+// supportsMultipleWordsToggle reports whether the New Game "multiple words per turn" toggle
+// applies to a variant. Only Russian games choose the rule; English is always standard, so
+// its toggle is not shown.
+export function supportsMultipleWordsToggle(v: Variant): boolean {
+  return VARIANT_LANGUAGE[v] === 'ru';
+}
+
+// multipleWordsForRequest resolves the per-turn word rule sent when starting a game of the
+// variant: Russian games carry the toggle's value, English games are silently standard
+// (true), so matchmaking and game creation stay one uniform path.
+export function multipleWordsForRequest(v: Variant, toggle: boolean): boolean {
+  return supportsMultipleWordsToggle(v) ? toggle : true;
+}

ui/src/screens/NewGame.svelte

@@ -7,7 +7,13 @@
   import { navigate } from '../lib/router.svelte';
   import { t, type MessageKey } from '../lib/i18n/index.svelte';
   import type { AccountRef, Variant } from '../lib/model';
-  import { availableVariants, VARIANT_FLAG, VARIANT_RULES } from '../lib/variants';
+  import {
+    availableVariants,
+    VARIANT_FLAG,
+    VARIANT_RULES,
+    supportsMultipleWordsToggle,
+    multipleWordsForRequest,
+  } from '../lib/variants';
 
   // The auto-match move clock (mirrors backend game.DefaultTurnTimeout = 24h).
   const AUTO_MATCH_HOURS = 24;
@@ -15,6 +21,10 @@
   // The offered variants are gated by the languages the sign-in service supports;
   // the auto-match list and the friend-invite picker both use this.
   const variants = $derived(availableVariants(app.session?.supportedLanguages));
+  // "Multiple words per turn" off is the single-word rule; it is offered for Russian games
+  // only (English is always standard and shows no toggle). Shared by both flows.
+  let multipleWords = $state(false);
+  const autoHasRussian = $derived(variants.some((v) => supportsMultipleWordsToggle(v.id)));
   const timeouts = [
     { secs: 300, key: 'time.minutes' as MessageKey, n: 5 },
     { secs: 1800, key: 'time.minutes' as MessageKey, n: 30 },
@@ -70,7 +80,7 @@
     searching = true;
     matched = false;
     try {
-      const r = await gateway.lobbyEnqueue(v);
+      const r = await gateway.lobbyEnqueue(v, multipleWordsForRequest(v, multipleWords));
       if (r.matched && r.game) {
         matched = true;
         searching = false;
@@ -137,6 +147,7 @@
         hintsAllowed: hints > 0,
         hintsPerPlayer: hints,
         dropoutTiles: 'remove',
+        multipleWordsPerTurn: multipleWordsForRequest(inviteVariant, multipleWords),
       });
       showToast(t('new.invited'));
       navigate('/');
@@ -171,6 +182,12 @@
 
       {#if mode === 'auto'}
         <p class="subtitle">{t('new.subtitle')}</p>
+        {#if autoHasRussian}
+          <label class="toggle">
+            <span>{t('new.multipleWordsPerTurn')}</span>
+            <input type="checkbox" bind:checked={multipleWords} />
+          </label>
+        {/if}
         <div class="variants">
           {#each variants as v (v.id)}
             <button class="variant" onclick={() => find(v.id)} disabled={!connection.online}>
@@ -225,6 +242,12 @@
               </select>
             </label>
           </div>
+          {#if inviteVariant && supportsMultipleWordsToggle(inviteVariant)}
+            <label class="toggle">
+              <span>{t('new.multipleWordsPerTurn')}</span>
+              <input type="checkbox" bind:checked={multipleWords} />
+            </label>
+          {/if}
           <button class="invite" disabled={selected.length === 0 || !inviteVariant || !connection.online} onclick={sendInvite}>{t('new.invite')}</button>
         </div>
       {/if}
@@ -385,6 +408,21 @@
   .field select.placeholder {
     color: var(--text-muted);
   }
+  .toggle {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    gap: 8px;
+    padding: 11px;
+    border: 1px solid var(--border);
+    background: var(--surface);
+    border-radius: var(--radius-sm);
+    user-select: none;
+  }
+  .toggle span {
+    font-size: 0.85rem;
+    color: var(--text);
+  }
   .muted {
     color: var(--text-muted);
     margin: 0;