diff --git a/tests/e2e/inspector-dock-layout.spec.js b/tests/e2e/inspector-dock-layout.spec.js
index 6bd3702a..f175c729 100644
--- a/tests/e2e/inspector-dock-layout.spec.js
+++ b/tests/e2e/inspector-dock-layout.spec.js
@@ -153,11 +153,18 @@ test.describe('docked right-inspector dock-aware width (#586 findings 2a/2b)', (
     expect(Math.round(before.width)).toBe(500);
 
     await page.setViewportSize({ width: 900, height: 800 });
+    // #599: `setViewportSize` resolves as soon as the viewport is applied, but
+    // the DISPLAYED width above is recomputed by app-shell.ts's
+    // `reclampInspectorWidth`, run from a real `window` 'resize' event
+    // LISTENER — dispatched asynchronously relative to that resolution, and
+    // more likely to lose the race under parallel load. Poll for the settled
+    // width instead of reading it on the very next microtask.
+    await expect.poll(async () => Math.round((await inspectorHost.boundingBox()).width))
+      // Default sidebarPx (248) + 2 handles (14) reserved, minus CENTRE_MIN_PX
+      // (320): ceiling = 900-262-320 = 318, below the shared 320 floor — clamp
+      // floors it at 320 exactly.
+      .toBe(320);
     const after = await inspectorHost.boundingBox();
-    // Default sidebarPx (248) + 2 handles (14) reserved, minus CENTRE_MIN_PX
-    // (320): ceiling = 900-262-320 = 318, below the shared 320 floor — clamp
-    // floors it at 320 exactly.
-    expect(Math.round(after.width)).toBe(320);
     expect(after.width).toBeLessThan(before.width);
 
     test.info().annotations.push(
diff --git a/tests/e2e/tile-open-workbench.spec.js b/tests/e2e/tile-open-workbench.spec.js
index 98a81c08..3dca7b99 100644
--- a/tests/e2e/tile-open-workbench.spec.js
+++ b/tests/e2e/tile-open-workbench.spec.js
@@ -361,7 +361,15 @@ test('widen doubles a grid tile\'s rendered width, preserves its height, then wr
   // until #564.
   expect(wide.width).toBeGreaterThan(before.width);
   expect(wide.height).toBe(before.height);
-  expect((await page.evaluate(() => window.__dashboard('sales'))).items['t-sales'])
+  // #599: the widen press applies OPTIMISTICALLY first (`runCommand`,
+  // src/ui/dashboard.ts) — the geometry above is already settled by the time
+  // `widen.click()` resolves, but the PERSISTED commit this reads is a
+  // separate, fire-and-forget `app.mutateWorkspace` call that lands later.
+  // Poll rather than reading it on the very next microtask, matching the same
+  // commit-republish race the later "narrow tile" test already guards
+  // against (its own "Read defensively" comment, below).
+  await expect.poll(async () => (await page.evaluate(() => window.__dashboard('sales')))
+    ?.items?.['t-sales'] ?? null)
     .toEqual({ grid: { span: 12, height: 2 } });
 
   // At the maximum the next press wraps to a single column.