feat: add first page with auth and containers list and agents

server/internal/broker/broker.go

@@ -0,0 +1,55 @@
+package broker
+
+import (
+	"encoding/json"
+	"sync"
+)
+
+// Event is a JSON-serialisable message pushed to WebSocket clients.
+type Event struct {
+	Type    string `json:"type"`
+	AgentID string `json:"agent_id,omitempty"`
+	Payload any    `json:"payload"`
+}
+
+type subscriber chan []byte
+
+// Broker fan-outs events to all registered WebSocket subscribers.
+type Broker struct {
+	mu   sync.RWMutex
+	subs map[subscriber]struct{}
+}
+
+func New() *Broker {
+	return &Broker{subs: make(map[subscriber]struct{})}
+}
+
+func (b *Broker) Subscribe() subscriber {
+	ch := make(subscriber, 32)
+	b.mu.Lock()
+	b.subs[ch] = struct{}{}
+	b.mu.Unlock()
+	return ch
+}
+
+func (b *Broker) Unsubscribe(ch subscriber) {
+	b.mu.Lock()
+	delete(b.subs, ch)
+	b.mu.Unlock()
+	close(ch)
+}
+
+func (b *Broker) Publish(evt Event) {
+	data, err := json.Marshal(evt)
+	if err != nil {
+		return
+	}
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	for ch := range b.subs {
+		select {
+		case ch <- data:
+		default: // drop if subscriber is slow
+		}
+	}
+}