diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 3be43eb..0ff14c9 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -1,7 +1,9 @@
 # GitHub Actions twin of .gitea/workflows/macos.yml.
 # Deltas from the Gitea file (everything else is the same jobs/steps):
-#   - runs-on macos-14: github.com retired macos-12 (the Gitea runner label).
-#     The Gitea workflow already notes macos-14 works for this pipeline.
+#   - runs-on macos-14: github.com retired macos-12. Do not use
+#     macos-latest — in 2026 that is macos-26-arm64, where a 1280×800
+#     window hangs off the virtual display and XCTest marks sidebar
+#     controls (x ≈ -116) as not hittable (run 34864198118).
 #   - actions/upload-artifact@v4: v3 is shut down on github.com. Gitea act_runner
 #     still uses v3.
 #   - No NODE_EXTRA_CA_CERTS / System keychain bundle: that is only for the
@@ -25,7 +27,7 @@ permissions:
 
 jobs:
   build-and-test:
-    runs-on: macos-latest
+    runs-on: macos-14
     env:
       DERIVED: build/DerivedData-test
     steps:
@@ -182,7 +184,7 @@ jobs:
 
   package:
     needs: build-and-test
-    runs-on: macos-latest
+    runs-on: macos-14
     if: github.ref == 'refs/heads/develop' || startsWith(github.ref, 'refs/tags/v')
     permissions:
       contents: write
diff --git a/Sources/ICCery/ICCeryApp.swift b/Sources/ICCery/ICCeryApp.swift
index 8535ad9..29d2f5e 100644
--- a/Sources/ICCery/ICCeryApp.swift
+++ b/Sources/ICCery/ICCeryApp.swift
@@ -56,10 +56,41 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
     }
 
     /// docs/21 §Shell: 1280×800 content, min 1100×700, centred.
+    /// GitHub-hosted Macs (and any display smaller than 1280×800) must
+    /// not get a window that hangs off-screen — XCTest then reports
+    /// sidebar controls at negative x as not hittable (run 34864198118).
     private func configureMainWindow(_ window: NSWindow) {
-        window.setContentSize(NSSize(width: 1280, height: 800))
-        window.contentMinSize = NSSize(width: 1100, height: 700)
+        let desired = NSSize(width: 1280, height: 800)
+        let minimum = NSSize(width: 1100, height: 700)
+        let visible = (window.screen ?? NSScreen.main)?.visibleFrame
+            ?? NSRect(origin: .zero, size: desired)
+
+        window.contentMinSize = NSSize(
+            width: min(minimum.width, visible.width),
+            height: min(minimum.height, visible.height)
+        )
+        window.setContentSize(NSSize(
+            width: min(desired.width, visible.width),
+            height: min(desired.height, max(minimum.height, visible.height - 40))
+        ))
         window.center()
+
+        var frame = window.frame
+        if frame.width > visible.width {
+            frame.size.width = visible.width
+        }
+        if frame.height > visible.height {
+            frame.size.height = visible.height
+        }
+        frame.origin.x = min(
+            max(frame.origin.x, visible.minX),
+            visible.maxX - frame.width
+        )
+        frame.origin.y = min(
+            max(frame.origin.y, visible.minY),
+            visible.maxY - frame.height
+        )
+        window.setFrame(frame, display: true)
     }
 
     /// Dock-click reopen: let the WindowGroup re-show or recreate the