feat(ui): single-word rule indicators + auto-match select redesign

Surface the per-game "single word" rule to the client and refine the
random-opponent New Game screen.

- Wire: thread multiple_words_per_turn into the GameView and Invitation
  FlatBuffers tables (Go + TS regenerated), through pkg/wire builders and both
  the backend push-event and gateway REST paths.
- In-game indicators (single-word games only): a small 1 in the status bar's
  score-preview slot (yields to the live preview) and a centred "One word per
  turn" label in the history-drawer header. Standard games show neither.
- Invitation card gains a "One word per turn" line for single-word invitations.
- Auto-match redesign: variant plaques are mutually-exclusive selects (highlight
  on tap, no longer enqueue); a lone offered variant is pre-selected; a bottom
  "Start game" button (disabled until a variant is chosen) confirms. The rule
  toggle appears once a Russian variant is selected.
- Tests: e2e for the new auto flow and the in-game indicator (mock g3 is a
  single-word game); mock/data + fixtures carry the new field. Docs: UI_DESIGN.

backend/internal/game/eventwire.go

@@ -35,17 +35,18 @@ func gameSummary(g Game, names []string) notify.GameSummary {
 		last = *g.FinishedAt
 	}
 	return notify.GameSummary{
-		ID:               g.ID.String(),
-		Variant:          g.Variant.String(),
-		DictVersion:      g.DictVersion,
-		Status:           g.Status,
-		Players:          g.Players,
-		ToMove:           g.ToMove,
-		TurnTimeoutSecs:  int(g.TurnTimeout.Seconds()),
-		MoveCount:        g.MoveCount,
-		EndReason:        g.EndReason,
-		Seats:            seats,
-		LastActivityUnix: last.Unix(),
+		ID:                   g.ID.String(),
+		Variant:              g.Variant.String(),
+		DictVersion:          g.DictVersion,
+		Status:               g.Status,
+		Players:              g.Players,
+		ToMove:               g.ToMove,
+		TurnTimeoutSecs:      int(g.TurnTimeout.Seconds()),
+		MultipleWordsPerTurn: g.MultipleWordsPerTurn,
+		MoveCount:            g.MoveCount,
+		EndReason:            g.EndReason,
+		Seats:                seats,
+		LastActivityUnix:     last.Unix(),
 	}
 }
 

backend/internal/lobby/invitations.go

@@ -159,17 +159,18 @@ func (svc *InvitationService) invitationSummary(ctx context.Context, inv Invitat
 		gameID = inv.GameID.String()
 	}
 	return notify.InvitationSummary{
-		ID:              inv.ID.String(),
-		Inviter:         notify.AccountRef{AccountID: inv.InviterID.String(), DisplayName: name(inv.InviterID)},
-		Invitees:        invitees,
-		Variant:         inv.Settings.Variant.String(),
-		TurnTimeoutSecs: int(inv.Settings.TurnTimeout / time.Second),
-		HintsAllowed:    inv.Settings.HintsAllowed,
-		HintsPerPlayer:  inv.Settings.HintsPerPlayer,
-		DropoutTiles:    inv.Settings.DropoutTiles.String(),
-		Status:          inv.Status,
-		GameID:          gameID,
-		ExpiresAtUnix:   inv.ExpiresAt.Unix(),
+		ID:                   inv.ID.String(),
+		Inviter:              notify.AccountRef{AccountID: inv.InviterID.String(), DisplayName: name(inv.InviterID)},
+		Invitees:             invitees,
+		Variant:              inv.Settings.Variant.String(),
+		TurnTimeoutSecs:      int(inv.Settings.TurnTimeout / time.Second),
+		HintsAllowed:         inv.Settings.HintsAllowed,
+		HintsPerPlayer:       inv.Settings.HintsPerPlayer,
+		MultipleWordsPerTurn: inv.Settings.MultipleWordsPerTurn,
+		DropoutTiles:         inv.Settings.DropoutTiles.String(),
+		Status:               inv.Status,
+		GameID:               gameID,
+		ExpiresAtUnix:        inv.ExpiresAt.Unix(),
 	}
 }
 

backend/internal/notify/encode.go

@@ -28,17 +28,18 @@ func toWireGame(g GameSummary) wire.GameView {
 		}
 	}
 	return wire.GameView{
-		ID:               g.ID,
-		Variant:          g.Variant,
-		DictVersion:      g.DictVersion,
-		Status:           g.Status,
-		Players:          g.Players,
-		ToMove:           g.ToMove,
-		TurnTimeoutSecs:  g.TurnTimeoutSecs,
-		MoveCount:        g.MoveCount,
-		EndReason:        g.EndReason,
-		Seats:            seats,
-		LastActivityUnix: g.LastActivityUnix,
+		ID:                   g.ID,
+		Variant:              g.Variant,
+		DictVersion:          g.DictVersion,
+		Status:               g.Status,
+		Players:              g.Players,
+		ToMove:               g.ToMove,
+		TurnTimeoutSecs:      g.TurnTimeoutSecs,
+		MultipleWordsPerTurn: g.MultipleWordsPerTurn,
+		MoveCount:            g.MoveCount,
+		EndReason:            g.EndReason,
+		Seats:                seats,
+		LastActivityUnix:     g.LastActivityUnix,
 	}
 }
 
@@ -102,16 +103,17 @@ func buildInvitation(b *flatbuffers.Builder, inv InvitationSummary) flatbuffers.
 		}
 	}
 	return wire.BuildInvitation(b, wire.Invitation{
-		ID:              inv.ID,
-		Inviter:         wire.AccountRef{AccountID: inv.Inviter.AccountID, DisplayName: inv.Inviter.DisplayName},
-		Invitees:        invitees,
-		Variant:         inv.Variant,
-		TurnTimeoutSecs: inv.TurnTimeoutSecs,
-		HintsAllowed:    inv.HintsAllowed,
-		HintsPerPlayer:  inv.HintsPerPlayer,
-		DropoutTiles:    inv.DropoutTiles,
-		Status:          inv.Status,
-		GameID:          inv.GameID,
-		ExpiresAtUnix:   inv.ExpiresAtUnix,
+		ID:                   inv.ID,
+		Inviter:              wire.AccountRef{AccountID: inv.Inviter.AccountID, DisplayName: inv.Inviter.DisplayName},
+		Invitees:             invitees,
+		Variant:              inv.Variant,
+		TurnTimeoutSecs:      inv.TurnTimeoutSecs,
+		HintsAllowed:         inv.HintsAllowed,
+		HintsPerPlayer:       inv.HintsPerPlayer,
+		MultipleWordsPerTurn: inv.MultipleWordsPerTurn,
+		DropoutTiles:         inv.DropoutTiles,
+		Status:               inv.Status,
+		GameID:               inv.GameID,
+		ExpiresAtUnix:        inv.ExpiresAtUnix,
 	})
 }

backend/internal/notify/payload.go

@@ -21,17 +21,18 @@ type SeatStanding struct {
 // (mirrors scrabblefb.GameView). LastActivityUnix is the lobby sort key: the current
 // turn's start for an active game, the finish time once finished.
 type GameSummary struct {
-	ID               string
-	Variant          string
-	DictVersion      string
-	Status           string
-	Players          int
-	ToMove           int
-	TurnTimeoutSecs  int
-	MoveCount        int
-	EndReason        string
-	Seats            []SeatStanding
-	LastActivityUnix int64
+	ID                   string
+	Variant              string
+	DictVersion          string
+	Status               string
+	Players              int
+	ToMove               int
+	TurnTimeoutSecs      int
+	MultipleWordsPerTurn bool
+	MoveCount            int
+	EndReason            string
+	Seats                []SeatStanding
+	LastActivityUnix     int64
 }
 
 // AlphabetLetter is one variant alphabet entry (a display-only row) embedded in an
@@ -75,15 +76,16 @@ type InvitationInvitee struct {
 // InvitationSummary is a friend-game invitation carried by the NotifyInvitation event so
 // the client adds it to its lobby list without a refetch (mirrors scrabblefb.Invitation).
 type InvitationSummary struct {
-	ID              string
-	Inviter         AccountRef
-	Invitees        []InvitationInvitee
-	Variant         string
-	TurnTimeoutSecs int
-	HintsAllowed    bool
-	HintsPerPlayer  int
-	DropoutTiles    string
-	Status          string
-	GameID          string
-	ExpiresAtUnix   int64
+	ID                   string
+	Inviter              AccountRef
+	Invitees             []InvitationInvitee
+	Variant              string
+	TurnTimeoutSecs      int
+	HintsAllowed         bool
+	HintsPerPlayer       int
+	MultipleWordsPerTurn bool
+	DropoutTiles         string
+	Status               string
+	GameID               string
+	ExpiresAtUnix        int64
 }

backend/internal/server/dto.go

@@ -81,15 +81,16 @@ type seatDTO struct {
 
 // gameDTO is the shared game summary.
 type gameDTO struct {
-	ID              string `json:"id"`
-	Variant         string `json:"variant"`
-	DictVersion     string `json:"dict_version"`
-	Status          string `json:"status"`
-	Players         int    `json:"players"`
-	ToMove          int    `json:"to_move"`
-	TurnTimeoutSecs int    `json:"turn_timeout_secs"`
-	MoveCount       int    `json:"move_count"`
-	EndReason       string `json:"end_reason"`
+	ID                   string `json:"id"`
+	Variant              string `json:"variant"`
+	DictVersion          string `json:"dict_version"`
+	Status               string `json:"status"`
+	Players              int    `json:"players"`
+	ToMove               int    `json:"to_move"`
+	TurnTimeoutSecs      int    `json:"turn_timeout_secs"`
+	MultipleWordsPerTurn bool   `json:"multiple_words_per_turn"`
+	MoveCount            int    `json:"move_count"`
+	EndReason            string `json:"end_reason"`
 	// LastActivityUnix is the lobby sort key: the current turn's start for an active
 	// game, the finish time once finished.
 	LastActivityUnix int64     `json:"last_activity_unix"`
@@ -198,17 +199,18 @@ func gameDTOFromGame(g game.Game) gameDTO {
 		last = *g.FinishedAt
 	}
 	return gameDTO{
-		ID:               g.ID.String(),
-		Variant:          g.Variant.String(),
-		DictVersion:      g.DictVersion,
-		Status:           g.Status,
-		Players:          g.Players,
-		ToMove:           g.ToMove,
-		TurnTimeoutSecs:  int(g.TurnTimeout.Seconds()),
-		MoveCount:        g.MoveCount,
-		EndReason:        g.EndReason,
-		LastActivityUnix: last.Unix(),
-		Seats:            seats,
+		ID:                   g.ID.String(),
+		Variant:              g.Variant.String(),
+		DictVersion:          g.DictVersion,
+		Status:               g.Status,
+		Players:              g.Players,
+		ToMove:               g.ToMove,
+		TurnTimeoutSecs:      int(g.TurnTimeout.Seconds()),
+		MultipleWordsPerTurn: g.MultipleWordsPerTurn,
+		MoveCount:            g.MoveCount,
+		EndReason:            g.EndReason,
+		LastActivityUnix:     last.Unix(),
+		Seats:                seats,
 	}
 }