test(e2e): symmetric page-load guard + document the pause-settle window (review polish)

tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/Deployment/DeploymentsRealtimeTests.cs

@@ -84,6 +84,9 @@ public class DeploymentsRealtimeTests : IClassFixture<DeploymentFixture>
             var page = await _pw.NewAuthenticatedPageAsync();
             await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/deployment/deployments");
             await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+            // Confirm the page loaded before interacting (symmetric with Fact A) — a failed
+            // load then surfaces as a clear heading-miss rather than a confusing Pause timeout.
+            await Assertions.Expect(page.Locator("h4:has-text('Deployment Status')")).ToBeVisibleAsync();
 
             // Pause — the click round-trips over the circuit, so _autoRefresh is committed
             // false before the deploy below. The button flipping to "Resume" proves it.
@@ -93,8 +96,13 @@ public class DeploymentsRealtimeTests : IClassFixture<DeploymentFixture>
 
             await CliRunner.DeployInstanceAsync(instanceId);
 
-            // Paused: StatusChanged is ignored, so the row is NOT auto-added. Settle briefly to
-            // give any (erroneous) push time to manifest, then assert absence.
+            // Paused: StatusChanged is ignored, so the row is NOT auto-added. The push chain
+            // (deploy write → StatusChanged → InvokeAsync re-render → SignalR diff) completes
+            // well under a second on a healthy cluster, so a 2s settle is ample to let any
+            // erroneous push manifest before we assert absence. This is the one deliberate
+            // fixed wait — a negative real-time assertion has no DOM event to await on the
+            // "stayed absent" path. The Refresh-restores assertion below is the independent
+            // positive guard if a loaded cluster ever makes this settle empirically tight.
             var row = page.Locator("table tbody tr", new() { HasText = uniqueName });
             await page.WaitForTimeoutAsync(2_000);
             await Assertions.Expect(row).ToHaveCountAsync(0);