diff --git a/tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/SiteCrudTests.cs b/tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/SiteCrudTests.cs
index 41befbc9..d794f012 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/SiteCrudTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/SiteCrudTests.cs
@@ -195,6 +195,127 @@ public class SiteCrudTests
         }
     }
 
+    /// <summary>
+    /// Creating a site whose Identifier collides with the always-present seeded
+    /// <c>site-a</c> must fail at save and persist nothing. SiteForm.SaveSite()
+    /// catches the duplicate DbUpdateException → <c>_formError = "Save failed: …"</c>
+    /// (a raw EF message) and stays on /create. The Name is deliberately distinct so
+    /// only the SiteIdentifier unique index can trip (not the Name unique index).
+    /// </summary>
+    [SkippableFact]
+    public async Task Create_DuplicateIdentifier_ShowsSaveFailedError()
+    {
+        Skip.IfNot(await ClusterAvailability.IsAvailableAsync(), ClusterAvailability.SkipReason);
+
+        // Confirm the collision target exists (site-a is a core cluster seed; throws if absent).
+        await CliRunner.ResolveSiteIdAsync("site-a");
+
+        // Distinct name so the failure can only be the SiteIdentifier unique index.
+        var distinctName = $"zztest-dup-{Guid.NewGuid():N}"[..16];
+
+        var page = await _fixture.NewAuthenticatedPageAsync();
+
+        try
+        {
+            await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/admin/sites/create");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            // Identifier collides with the seeded site-a; Name is distinct. Node addresses blank.
+            await page.Locator("label:has-text('Identifier') + input.form-control.form-control-sm").FillAsync("site-a");
+            await page.Locator("label:has-text('Name') + input.form-control.form-control-sm").FillAsync(distinctName);
+
+            await page.ClickAsync("button.btn.btn-success.btn-sm:has-text('Save')");
+
+            // The inline error surface must report the failed save and we must stay on /create.
+            // The full message is a raw DbUpdateException — assert only the "Save failed" prefix.
+            await Expect(page.Locator("div.text-danger.small.mt-2")).ToContainTextAsync("Save failed");
+            await Assertions.Expect(page)
+                .ToHaveURLAsync(new System.Text.RegularExpressions.Regex("/admin/sites/create"));
+        }
+        finally
+        {
+            // Defensive: the failed create persists nothing, but if a stray site by the
+            // distinct name somehow exists, best-effort delete it (swallow not-found).
+            try
+            {
+                await CliRunner.DeleteSiteAsync(await CliRunner.ResolveSiteIdAsync(distinctName));
+            }
+            catch
+            {
+                // Nothing persisted (expected) or cluster unreachable — ignore.
+            }
+        }
+    }
+
+    /// <summary>
+    /// Editing a site and clicking Cancel must discard the change. SiteForm's Cancel
+    /// (like Back) calls GoBack() → /admin/sites with NO dirty-check and NO persistence,
+    /// so re-opening the edit must show the ORIGINAL (empty) Description.
+    /// </summary>
+    [SkippableFact]
+    public async Task EditCancel_DiscardsChanges()
+    {
+        Skip.IfNot(await ClusterAvailability.IsAvailableAsync(), ClusterAvailability.SkipReason);
+
+        var hex = Guid.NewGuid().ToString("N")[..8];
+        var ident = $"zztest-{hex}";
+        var name = $"zztest-site-{hex}";
+
+        var page = await _fixture.NewAuthenticatedPageAsync();
+
+        try
+        {
+            // ── CREATE (mirror the round-trip test's create steps) ──────────────────────
+            await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/admin/sites/create");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            await page.Locator("label:has-text('Identifier') + input.form-control.form-control-sm").FillAsync(ident);
+            await page.Locator("label:has-text('Name') + input.form-control.form-control-sm").FillAsync(name);
+
+            await page.ClickAsync("button.btn.btn-success.btn-sm:has-text('Save')");
+            await PlaywrightFixture.WaitForPathAsync(page, "/admin/sites", excludePath: "/create");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            // ── EDIT → change Description → CANCEL ──────────────────────────────────────
+            var card = page.Locator("div.card", new() { HasText = name });
+            await Assertions.Expect(card).ToBeVisibleAsync();
+            await card.Locator("button.btn.btn-outline-primary.btn-sm:has-text('Edit')").ClickAsync();
+
+            await PlaywrightFixture.WaitForPathAsync(page, "/edit", excludePath: "/create");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            await page.Locator("label:has-text('Description') + input.form-control.form-control-sm")
+                .FillAsync("zztest-CANCELLED-EDIT");
+
+            await page.ClickAsync("button:has-text('Cancel')");
+            await PlaywrightFixture.WaitForPathAsync(page, "/admin/sites", excludePath: "/edit");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            // ── RE-OPEN EDIT → Description must be the ORIGINAL (empty) ──────────────────
+            var cardAfterCancel = page.Locator("div.card", new() { HasText = name });
+            await Assertions.Expect(cardAfterCancel).ToBeVisibleAsync();
+            await cardAfterCancel.Locator("button.btn.btn-outline-primary.btn-sm:has-text('Edit')").ClickAsync();
+
+            await PlaywrightFixture.WaitForPathAsync(page, "/edit", excludePath: "/create");
+            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+
+            var descInput = page.Locator("label:has-text('Description') + input.form-control.form-control-sm");
+            await Expect(descInput).ToHaveValueAsync("");
+        }
+        finally
+        {
+            // Best-effort teardown: delete the site via CLI.
+            try
+            {
+                await CliRunner.DeleteSiteAsync(await CliRunner.ResolveSiteIdAsync(ident));
+            }
+            catch
+            {
+                // Already gone or cluster unreachable — ignore.
+            }
+        }
+    }
+
     private static ILocatorAssertions Expect(ILocator locator) =>
         Assertions.Expect(locator);
 }