feat: make notification delivery durable

server/internal/httpapi/notifications_internal_test.go

@@ -0,0 +1,18 @@
+package httpapi
+
+import (
+	"testing"
+	"time"
+)
+
+func TestNotificationRetryDelay(t *testing.T) {
+	want := []time.Duration{30 * time.Second, time.Minute, 2 * time.Minute, 4 * time.Minute, 8 * time.Minute}
+	for index, expected := range want {
+		if got := notificationRetryDelay(index + 1); got != expected {
+			t.Fatalf("attempt %d: got %s want %s", index+1, got, expected)
+		}
+	}
+	if got := notificationRetryDelay(20); got != 30*time.Minute {
+		t.Fatalf("retry cap: got %s want 30m", got)
+	}
+}