Changeset 0.11.0 (#62)

server/events/bus.go

@@ -3,6 +3,7 @@ package events
 import (
 	"strings"
 	"sync"
+	"time"
 )
 
 // Bus is a labeled publish/subscribe event bus.
@@ -114,3 +115,28 @@ func match(label, pattern string) bool {
 	prefix := pattern[:len(pattern)-1] // "chat.message." from "chat.message.*"
 	return strings.HasPrefix(label, prefix)
 }
+
+// WaitFor subscribes to an exact label and blocks until an event arrives
+// or the timeout elapses. Returns the event and true, or a zero Event and
+// false on timeout. The subscription is automatically removed after.
+//
+// Used by the browser tool bridge: the server publishes tool.call.{id}
+// to the client and then calls WaitFor("tool.result.{id}", 30s) to block
+// until the browser returns the result.
+func (b *Bus) WaitFor(label string, timeout time.Duration) (Event, bool) {
+	ch := make(chan Event, 1)
+	unsub := b.Subscribe(label, func(e Event) {
+		select {
+		case ch <- e:
+		default:
+		}
+	})
+	defer unsub()
+
+	select {
+	case e := <-ch:
+		return e, true
+	case <-time.After(timeout):
+		return Event{}, false
+	}
+}