websocket 三 client 结构体去重：嵌入共享 wsClientCore（close/enqueue 单份实现）

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internal/apps/openflare/websocket/client_core.go

@@ -0,0 +1,45 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package websocket
+
+import (
+	"sync"
+
+	"github.com/gorilla/websocket"
+)
+
+// wsClientCore holds the state and lifecycle shared by all WebSocket client
+// variants (agent/relay/flared). Embed it; call close exactly-once semantics
+// are guaranteed via once.
+type wsClientCore struct {
+	nodeID string
+	conn   *websocket.Conn
+	send   chan Message
+	done   chan struct{}
+	once   sync.Once
+}
+
+// close tears down the connection at most once.
+func (c *wsClientCore) close() {
+	if c == nil {
+		return
+	}
+	c.once.Do(func() {
+		close(c.done)
+		_ = c.conn.Close()
+	})
+}
+
+// enqueue best-effort delivers message; it never blocks and fails fast when
+// the client is closed or its send buffer is full.
+func (c *wsClientCore) enqueue(message Message) bool {
+	select {
+	case <-c.done:
+		return false
+	case c.send <- message:
+		return true
+	default:
+		return false
+	}
+}