refactor: replace hardcoded NATS subjects with typed helpers

Add GameSubject/ChatSubject helpers to connect4 and snake packages,
eliminating magic string concatenation from handlers and main.go.

connect4/types.go

@@ -6,6 +6,12 @@ import (
 	"github.com/ryanhamamura/games/player"
 )
 
+// NATS subject helpers.
+const SubjectPrefix = "connect4"
+
+func GameSubject(gameID string) string { return SubjectPrefix + "." + gameID }
+func ChatSubject(gameID string) string { return SubjectPrefix + ".chat." + gameID }
+
 type Player struct {
 	ID       player.ID
 	UserID   *string // UUID for authenticated users, nil for guests

features/c4game/handlers.go

@@ -111,14 +111,14 @@ func HandleGameEvents(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManag
 		))
 
 		chatCfg := c4ChatConfig(gameID)
-		room := chat.NewPersistentRoom(nc, "connect4.chat."+gameID, queries, gameID)
+		room := chat.NewPersistentRoom(nc, connect4.ChatSubject(gameID), queries, gameID)
 
 		// Send initial render
 		sendGameComponents(sse, gi, myColor, room, chatCfg)
 
 		// Subscribe to game state updates
 		gameCh := make(chan *nats.Msg, 64)
-		gameSub, err := nc.ChanSubscribe("connect4."+gameID, gameCh)
+		gameSub, err := nc.ChanSubscribe(connect4.GameSubject(gameID), gameCh)
 		if err != nil {
 			return
 		}
@@ -228,7 +228,7 @@ func HandleSendChat(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManager
 			Message:  signals.ChatMsg,
 			Time:     time.Now().UnixMilli(),
 		}
-		room := chat.NewPersistentRoom(nc, "connect4.chat."+gameID, queries, gameID)
+		room := chat.NewPersistentRoom(nc, connect4.ChatSubject(gameID), queries, gameID)
 		room.Send(msg)
 
 		sse := datastar.NewSSE(w, r)

features/snakegame/handlers.go

@@ -114,7 +114,7 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sm *scs.Sess
 
 		// Subscribe to game updates via NATS
 		gameCh := make(chan *nats.Msg, 64)
-		gameSub, err := nc.ChanSubscribe("snake."+gameID, gameCh)
+		gameSub, err := nc.ChanSubscribe(snake.GameSubject(gameID), gameCh)
 		if err != nil {
 			return
 		}
@@ -126,7 +126,7 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sm *scs.Sess
 		var room *chat.Room
 
 		if sg.Mode == snake.ModeMultiplayer {
-			room = chat.NewRoom(nc, "snake.chat."+gameID)
+			room = chat.NewRoom(nc, snake.ChatSubject(gameID))
 			chatCh, chatSub, err = room.Subscribe()
 			if err != nil {
 				return
@@ -247,7 +247,7 @@ func HandleSendChat(snakeStore *snake.SnakeStore, nc *nats.Conn, sm *scs.Session
 			Message:  signals.ChatMsg,
 		}
 
-		room := chat.NewRoom(nc, "snake.chat."+gameID)
+		room := chat.NewRoom(nc, snake.ChatSubject(gameID))
 		room.Send(msg)
 
 		sse := datastar.NewSSE(w, r)

main.go

@@ -73,12 +73,12 @@ func run(ctx context.Context) error {
 	// Game stores
 	store := connect4.NewStore(queries)
 	store.SetNotifyFunc(func(gameID string) {
-		nc.Publish("connect4."+gameID, nil) //nolint:errcheck // best-effort notification
+		nc.Publish(connect4.GameSubject(gameID), nil) //nolint:errcheck // best-effort notification
 	})
 
 	snakeStore := snake.NewSnakeStore(queries)
 	snakeStore.SetNotifyFunc(func(gameID string) {
-		nc.Publish("snake."+gameID, nil) //nolint:errcheck // best-effort notification
+		nc.Publish(snake.GameSubject(gameID), nil) //nolint:errcheck // best-effort notification
 	})
 
 	// Router

snake/types.go

@@ -7,6 +7,12 @@ import (
 	"github.com/ryanhamamura/games/player"
 )
 
+// NATS subject helpers.
+const SubjectPrefix = "snake"
+
+func GameSubject(gameID string) string { return SubjectPrefix + "." + gameID }
+func ChatSubject(gameID string) string { return SubjectPrefix + ".chat." + gameID }
+
 type Direction int
 
 const (