stabilize floating toolbar anchor assertion

Author: KSemenenko

ci-workflows-release-pr-validation.plan.md

@@ -222,11 +222,19 @@ Root-cause note:
   - mac-only keyboard shortcuts in UI tests (`Meta+A`, `Meta+Z`, `Meta+Shift+Z`) that broke Linux editor shortcuts and typing flows
   - browser-suite self-contention from `4` parallel xUnit workers inside one process on the slower GitHub runner
   - route/readiness assertions still relying on Playwright's short default timeouts instead of the suite's WASM-specific timeout budget
+- GitHub runs `23815330400` and `23815334683` proved the stability fixes removed all but one browser failure:
+  - `PrompterLive.App.UITests.EditorFloatingToolbarLayoutTests.EditorScreen_FloatingToolbarStaysPinnedAfterFloatingFormatAction`
+  - Root cause note: the test asserted `getBoundingClientRect().x/y` drift after the format action even though the production floating-toolbar contract preserves the inline/computed anchor (`left` and `top`) and the element itself is centered with `transform: translate(-50%, ...)`. Linux font/layout differences moved the rendered box without breaking the preserved anchor.
+  - Intended fix path: assert the preserved computed anchor coordinates instead of bounding-box drift, and keep the visibility check after the floating action.
 - Local validation after the browser-suite stability fixes passed:
   - `dotnet build /Users/ksemenenko/Developer/PrompterLive/PrompterLive.slnx -warnaserror`
   - `dotnet test /Users/ksemenenko/Developer/PrompterLive/tests/PrompterLive.Core.Tests/PrompterLive.Core.Tests.csproj --no-build`
   - `dotnet test /Users/ksemenenko/Developer/PrompterLive/tests/PrompterLive.App.Tests/PrompterLive.App.Tests.csproj --no-build`
   - `dotnet test /Users/ksemenenko/Developer/PrompterLive/tests/PrompterLive.App.UITests/PrompterLive.App.UITests.csproj --no-build`
+- Local validation after the floating-toolbar anchor assertion fix passed:
+  - `dotnet build /Users/ksemenenko/Developer/PrompterLive/PrompterLive.slnx -warnaserror`
+  - `dotnet test /Users/ksemenenko/Developer/PrompterLive/tests/PrompterLive.App.UITests/PrompterLive.App.UITests.csproj --no-build`
+  - `dotnet format /Users/ksemenenko/Developer/PrompterLive/PrompterLive.slnx`
 
 ## Final Validation Skills And Commands
 

tests/PrompterLive.App.UITests/Editor/EditorFloatingToolbarLayoutTests.cs

@@ -7,7 +7,8 @@ namespace PrompterLive.App.UITests;
 public sealed class EditorFloatingToolbarLayoutTests(StandaloneAppFixture fixture) : IClassFixture<StandaloneAppFixture>
 {
     private const string SegmentLineSelector = ".ed-src-line-segment";
-    private readonly record struct LayoutBounds(double X, double Y, double Width, double Height);
+    private readonly record struct LayoutBounds(double Y, double Height);
+    private readonly record struct ToolbarAnchor(double Left, double Top);
     private readonly StandaloneAppFixture _fixture = fixture;
 
     [Fact]
@@ -158,19 +159,20 @@ await sourceInput.EvaluateAsync(
             await Expect(floatingBar).ToBeVisibleAsync();
             await page.WaitForTimeoutAsync(BrowserTestConstants.Timing.FloatingToolbarSettleDelayMs);
 
-            var before = await GetRequiredBoundingBoxAsync(floatingBar);
+            var before = await GetRequiredAnchorAsync(floatingBar);
 
             await page.GetByTestId(UiTestIds.Editor.FloatEmphasis).ClickAsync();
+            await Expect(floatingBar).ToBeVisibleAsync();
             await page.WaitForTimeoutAsync(BrowserTestConstants.Timing.FloatingToolbarSettleDelayMs);
 
-            var after = await GetRequiredBoundingBoxAsync(floatingBar);
+            var after = await GetRequiredAnchorAsync(floatingBar);
 
             Assert.InRange(
-                Math.Abs(after.X - before.X),
+                Math.Abs(after.Left - before.Left),
                 0,
                 BrowserTestConstants.Editor.FloatingBarPinnedMaxDriftPx);
             Assert.InRange(
-                Math.Abs(after.Y - before.Y),
+                Math.Abs(after.Top - before.Top),
                 0,
                 BrowserTestConstants.Editor.FloatingBarPinnedMaxDriftPx);
         }
@@ -186,13 +188,23 @@ await locator.EvaluateAsync<LayoutBounds>(
             element => {
                 const rect = element.getBoundingClientRect();
                 return {
-                    x: rect.x,
                     y: rect.y,
-                    width: rect.width,
                     height: rect.height
                 };
             }
             """);
 
+    private static async Task<ToolbarAnchor> GetRequiredAnchorAsync(ILocator locator) =>
+        await locator.EvaluateAsync<ToolbarAnchor>(
+            """
+            element => {
+                const style = window.getComputedStyle(element);
+                return {
+                    left: Number.parseFloat(style.left),
+                    top: Number.parseFloat(style.top)
+                };
+            }
+            """);
+
     private readonly record struct SelectionGeometry(double SelectionTop);
 }