feat(centralui): hide OffsetPager on a single page, opt-in — NotificationReport enabled (M10 residual)

DECISION: a pager whose only two controls are permanently disabled is noise, so
the conventional behaviour ships — the bar is hidden when the result set is a
single page. NotificationReport, which raised the finding, opts in.

RATIONALE for opt-in rather than default-on. OffsetPager is shared, and its
summary span ("Page N of Y · T total") doubles as the ONLY total-count readout
on ConfigurationAuditLog — auto-hiding there would silently delete the result
count for every query returning under a page, and the existing Playwright
fixture asserts "3 total" on exactly such a query. So the behaviour lives in the
shared component (reusable for the next consumer) behind HideWhenSinglePage,
default false, which keeps every current consumer byte-identical.

The guard fires only when single-page-ness is POSITIVELY established:
PageCount <= 1 AND Page <= 1 AND !HasNextPage. A null TotalCount means the host
cannot count, so the bar renders — the controls never vanish while a further
page still exists.

NotificationReport's own Playwright pagination test seeds 51 rows (2 pages) and
is unaffected. 5 new bUnit tests cover hide-on-single-page, hide-on-empty,
show-on-multi-page, show-when-TotalCount-unknown, and the default-off path.

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Notifications/NotificationReport.razor

@@ -204,7 +204,8 @@
                      HasNextPage="@(_notifications.Count >= _pageSize)"
                      TotalCount="_totalCount"
                      PageSize="_pageSize"
-                     Disabled="_loading" />
+                     Disabled="_loading"
+                     HideWhenSinglePage="true" />
     }
 </div>
 
@@ -326,7 +327,7 @@
                         @* Email bodies are plain text (design: BCC delivery, plain text).
                            Rendered as preformatted text — never as a MarkupString, which
                            would be an XSS vector. *@
-                        <pre class="border rounded bg-light p-2 mb-0"
+                        <pre class="border rounded bg-body-secondary p-2 mb-0"
                              style="max-height: 320px; overflow: auto; white-space: pre-wrap; word-break: break-word;">@_detail.Body</pre>
                     }
                 </div>

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Shared/OffsetPager.razor

@@ -2,8 +2,11 @@
 
 @* Reusable offset-pagination bar.  Purely presentational: the host page
    owns page-number state, query execution, and the HasNextPage decision.
-   Parameters: Page, PageChanged, HasNextPage, TotalCount, PageSize, Disabled. *@
+   Parameters: Page, PageChanged, HasNextPage, TotalCount, PageSize, Disabled,
+   HideWhenSinglePage. *@
 
+@if (!IsSinglePageAndHidden)
+{
 <div class="d-flex align-items-center gap-2">
     <button class="btn btn-outline-secondary btn-sm"
             data-test="pager-prev"
@@ -21,6 +24,7 @@
         Next
     </button>
 </div>
+}
 
 @code {
     [Parameter] public int Page { get; set; } = 1;
@@ -30,8 +34,25 @@
     [Parameter] public int PageSize { get; set; }
     [Parameter] public bool Disabled { get; set; }
 
+    /// <summary>
+    /// When <c>true</c>, the whole bar is suppressed once the result set is
+    /// provably a single page — the conventional behaviour for a pager whose only
+    /// controls would be permanently disabled. Opt-in (default <c>false</c>)
+    /// because the summary span doubles as the "N total" result-count readout on
+    /// pages that have no other place to show it; a host that relies on that
+    /// readout leaves this off.
+    /// </summary>
+    [Parameter] public bool HideWhenSinglePage { get; set; }
+
     private bool HasPrev => Page > 1;
 
+    // Hide only when single-page-ness is POSITIVELY established: a known page
+    // count of 0/1, sitting on page 1, with no next page. A null TotalCount
+    // (host cannot count) or any disagreement between the signals renders the
+    // bar, so the controls never vanish while a further page still exists.
+    private bool IsSinglePageAndHidden =>
+        HideWhenSinglePage && PageCount is <= 1 && Page <= 1 && !HasNextPage;
+
     private int? PageCount =>
         TotalCount is { } t && PageSize > 0
             ? (int)Math.Ceiling(t / (double)PageSize)

tests/ZB.MOM.WW.ScadaBridge.CentralUI.Tests/Shared/OffsetPagerTests.cs

@@ -90,6 +90,85 @@ public class OffsetPagerTests : BunitContext
         Assert.Contains("230 total", summary.TextContent);
     }
 
+    // ── HideWhenSinglePage_HidesBar_OnSinglePage ──────────────────────────────
+
+    [Fact]
+    public void HideWhenSinglePage_HidesBar_OnSinglePage()
+    {
+        var cut = Render<OffsetPager>(ps => ps
+            .Add(p => p.Page, 1)
+            .Add(p => p.PageSize, 50)
+            .Add(p => p.TotalCount, 12)
+            .Add(p => p.HasNextPage, false)
+            .Add(p => p.HideWhenSinglePage, true));
+
+        Assert.Empty(cut.FindAll("[data-test='pager-prev']"));
+        Assert.Empty(cut.FindAll("[data-test='pager-next']"));
+        Assert.Empty(cut.FindAll("[data-test='pager-summary']"));
+    }
+
+    // ── HideWhenSinglePage_HidesBar_OnEmptyResult ─────────────────────────────
+
+    [Fact]
+    public void HideWhenSinglePage_HidesBar_OnEmptyResult()
+    {
+        var cut = Render<OffsetPager>(ps => ps
+            .Add(p => p.Page, 1)
+            .Add(p => p.PageSize, 50)
+            .Add(p => p.TotalCount, 0)
+            .Add(p => p.HasNextPage, false)
+            .Add(p => p.HideWhenSinglePage, true));
+
+        Assert.Empty(cut.FindAll("[data-test='pager-summary']"));
+    }
+
+    // ── HideWhenSinglePage_ShowsBar_WhenMultiplePages ─────────────────────────
+
+    [Fact]
+    public void HideWhenSinglePage_ShowsBar_WhenMultiplePages()
+    {
+        var cut = Render<OffsetPager>(ps => ps
+            .Add(p => p.Page, 1)
+            .Add(p => p.PageSize, 50)
+            .Add(p => p.TotalCount, 120)
+            .Add(p => p.HasNextPage, true)
+            .Add(p => p.HideWhenSinglePage, true));
+
+        Assert.Contains("Page 1 of 3", cut.Find("[data-test='pager-summary']").TextContent);
+    }
+
+    // ── HideWhenSinglePage_ShowsBar_WhenTotalCountUnknown ─────────────────────
+    // TotalCount is null (the host cannot count), so single-page-ness is not
+    // provable — the bar must stay so the user can still reach a further page.
+
+    [Fact]
+    public void HideWhenSinglePage_ShowsBar_WhenTotalCountUnknown()
+    {
+        var cut = Render<OffsetPager>(ps => ps
+            .Add(p => p.Page, 1)
+            .Add(p => p.PageSize, 50)
+            .Add(p => p.HasNextPage, false)
+            .Add(p => p.HideWhenSinglePage, true));
+
+        Assert.NotNull(cut.Find("[data-test='pager-summary']"));
+    }
+
+    // ── HideWhenSinglePage_Off_KeepsBarVisible_OnSinglePage ───────────────────
+    // Default (opt-out) behaviour: consumers that use the summary as their only
+    // "N total" readout keep the bar on a single page.
+
+    [Fact]
+    public void HideWhenSinglePage_Off_KeepsBarVisible_OnSinglePage()
+    {
+        var cut = Render<OffsetPager>(ps => ps
+            .Add(p => p.Page, 1)
+            .Add(p => p.PageSize, 50)
+            .Add(p => p.TotalCount, 3)
+            .Add(p => p.HasNextPage, false));
+
+        Assert.Contains("3 total", cut.Find("[data-test='pager-summary']").TextContent);
+    }
+
     // ── BothDisabled_WhenDisabled ─────────────────────────────────────────────
 
     [Fact]