watcher: startup notification no longer says every endpoint works (closes #230)

The startup notification ended "All notification channels are working.",
but it is written once and handed to every notification endpoint before
any delivery has succeeded or failed, so the claim was never checked and
was false whenever one endpoint refused it. It now says only that it is a
test sent to every configured notification endpoint. The startup
notification test checks the whole message.

Model: opus-5-5

TODO.md

@@ -19,6 +19,8 @@ trial run of the finished image: https://git.eeqj.de/sneak/dnswatcher/issues/149
 
 # Completed Steps
 
+- 2026-10-02: the startup notification no longer says every notification
+  endpoint works; it says it is a test sent to each of them (closes #230).
 - 2026-10-02: a Mattermost webhook that answers an HTTP error is logged as
   `mattermost notification failed`, not as a Slack failure (closes #227).
 - 2026-10-02: durations in the log are written as text such as `2m0s`, not as a

internal/watcher/watcher.go

@@ -1154,8 +1154,9 @@ func (w *Watcher) saveState() {
 
 // maybeSendTestNotification sends a startup status notification
 // after the first full scan completes, if SEND_TEST_NOTIFICATION
-// is enabled. The message is clearly informational ("all ok")
+// is enabled. The message is informational, not an error or anomaly
-// and not an error or anomaly alert.
+// alert. It is written before it reaches any endpoint, so it claims
+// nothing about whether the endpoints work.
 func (w *Watcher) maybeSendTestNotification(ctx context.Context) {
 	if !w.config.SendTestNotification {
 		return
@@ -1167,7 +1168,8 @@ func (w *Watcher) maybeSendTestNotification(ctx context.Context) {
 		"dnswatcher has started and completed its initial scan.\n"+
 			"Monitoring %d domain(s) and %d hostname(s).\n"+
 			"Tracking %d port endpoint(s) and %d TLS certificate(s).\n"+
-			"All notification channels are working.",
+			"This is a test notification, sent to every configured "+
+			"notification endpoint.",
 		len(snap.Domains),
 		len(snap.Hostnames),
 		len(snap.Ports),

internal/watcher/watcher_test.go

@@ -875,18 +875,27 @@ func TestSendTestNotification_ViaRun(t *testing.T) {
 
 	notifications := deps.notifier.getNotifications()
 
+	// No names are configured, so every count is 0.
+	wantMessage := "dnswatcher has started and completed its initial scan.\n" +
+		"Monitoring 0 domain(s) and 0 hostname(s).\n" +
+		"Tracking 0 port endpoint(s) and 0 TLS certificate(s).\n" +
+		"This is a test notification, sent to every configured " +
+		"notification endpoint."
+
 	found := false
 
 	for _, n := range notifications {
 		if n.Priority == "success" &&
-			n.Title == "✅ dnswatcher startup complete" {
+			n.Title == "✅ dnswatcher startup complete" &&
+			n.Message == wantMessage {
 			found = true
 		}
 	}
 
 	if !found {
 		t.Errorf(
-			"expected startup test notification, got: %v",
+			"expected startup test notification with message %q, got: %v",
+			wantMessage,
 			notifications,
 		)
 	}