refactor: race-safe Subscribe/Fetch API with channel-based Publish

- Add mutex-guarded send/stop on Subscription to prevent send-on-closed-channel
  panics and data races
- Split Subscribe (streams after EOSE) and Fetch (closes on EOSE) per NIP-01
- Rewrite Publish to use channel-based OK dispatch instead of calling Receive
  directly, which raced with the auto-started Listen goroutine
- Clean up all subscriptions when Listen exits so range loops terminate
- Update tests and examples for new API

1 files changed, 10 insertions, 25 deletions

diff --git a/example_test.go b/example_test.go
index 90dae0f..6d10ced 100644
--- a/example_test.go
+++ b/example_test.go
@@ -53,8 +53,7 @@ func Example_basic() {
 // ExampleRelay demonstrates connecting to a relay (requires network).
 // This is a documentation example - run with: go test -v -run ExampleRelay
 func ExampleRelay() {
-        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-        defer cancel()
+        ctx := context.Background()
 
         // Connect to a public relay
         relay, err := nostr.Connect(ctx, "wss://relay.damus.io")
@@ -66,35 +65,21 @@ func ExampleRelay() {
 
         fmt.Println("Connected to relay!")
 
-        // Subscribe to recent text notes
+        ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+        defer cancel()
+
+        // Fetch recent text notes (closes on EOSE)
         since := time.Now().Add(-1 * time.Hour).Unix()
-        sub, err := relay.Subscribe(ctx, "my-sub", nostr.Filter{
+        sub := relay.Fetch(ctx, nostr.Filter{
                 Kinds: []int{nostr.KindTextNote},
                 Since: &since,
                 Limit: 5,
         })
-        if err != nil {
-                fmt.Printf("Failed to subscribe: %v\n", err)
-                return
-        }
-
-        // Listen for events in the background
-        go relay.Listen(ctx)
 
-        // Collect events until EOSE
         eventCount := 0
-        for {
-                select {
-                case event := <-sub.Events:
-                        eventCount++
-                        fmt.Printf("Received event from %s...\n", event.PubKey[:8])
-                case <-sub.EOSE:
-                        fmt.Printf("Received %d events before EOSE\n", eventCount)
-                        sub.Close(ctx)
-                        return
-                case <-ctx.Done():
-                        fmt.Println("Timeout")
-                        return
-                }
+        for event := range sub.Events {
+                eventCount++
+                fmt.Printf("Received event from %s...\n", event.PubKey[:8])
         }
+        fmt.Printf("Received %d events\n", eventCount)
 }