fix(server): race WebSocket, SVG refusé, rows.Err, time.NewTicker

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/websocket/hub.go

@@ -8,24 +8,35 @@ import (
 	"github.com/gorilla/websocket"
 )
 
+type client struct {
+	conn *websocket.Conn
+	send chan []byte
+	mu   sync.Mutex
+}
+
 type Hub struct {
 	mu      sync.RWMutex
-	clients map[*websocket.Conn]struct{}
+	clients map[*websocket.Conn]*client
 }
 
 func NewHub() *Hub {
-	return &Hub{clients: make(map[*websocket.Conn]struct{})}
+	return &Hub{clients: make(map[*websocket.Conn]*client)}
 }
 
 func (h *Hub) Register(conn *websocket.Conn) {
+	c := &client{conn: conn, send: make(chan []byte, 64)}
 	h.mu.Lock()
-	h.clients[conn] = struct{}{}
+	h.clients[conn] = c
 	h.mu.Unlock()
+	go c.writePump()
 }
 
 func (h *Hub) Unregister(conn *websocket.Conn) {
 	h.mu.Lock()
-	delete(h.clients, conn)
+	if c, ok := h.clients[conn]; ok {
+		close(c.send)
+		delete(h.clients, conn)
+	}
 	h.mu.Unlock()
 }
 
@@ -37,9 +48,11 @@ func (h *Hub) Broadcast(msg interface{}) {
 	}
 	h.mu.RLock()
 	defer h.mu.RUnlock()
-	for conn := range h.clients {
-		if err := conn.WriteMessage(websocket.TextMessage, data); err != nil {
-			log.Printf("[ws] write: %v", err)
+	for _, c := range h.clients {
+		select {
+		case c.send <- data:
+		default:
+			// canal plein, client lent — on skip
 		}
 	}
 }
@@ -49,3 +62,13 @@ func (h *Hub) Count() int {
 	defer h.mu.RUnlock()
 	return len(h.clients)
 }
+
+func (c *client) writePump() {
+	defer c.conn.Close()
+	for data := range c.send {
+		if err := c.conn.WriteMessage(websocket.TextMessage, data); err != nil {
+			log.Printf("[ws] write: %v", err)
+			return
+		}
+	}
+}