diff --git a/apps/electron-backend-e2e/src/backup-roundtrip.e2e.ts b/apps/electron-backend-e2e/src/backup-roundtrip.e2e.ts
index d0e6df701..b02d42fe3 100644
--- a/apps/electron-backend-e2e/src/backup-roundtrip.e2e.ts
+++ b/apps/electron-backend-e2e/src/backup-roundtrip.e2e.ts
@@ -17,6 +17,7 @@ import {
     test,
     waitForXtreamWorkspaceReady,
 } from './electron-test-fixtures';
+import { readVisibleSidebarCategories } from './sidebar-categories.e2e-support';
 
 /**
  * Full backup round-trip through the real UI, DB worker and IPC stack:
@@ -237,32 +238,18 @@ async function pickVisibleCategoryWithContent(
     await expect
         .poll(
             async () => {
-                const categories = page.locator(
-                    'app-workspace-context-panel .category-item:visible'
+                const category = (
+                    await readVisibleSidebarCategories(page)
+                ).find(
+                    (candidate) =>
+                        candidate.id &&
+                        candidate.name &&
+                        candidate.itemCount > 0
                 );
-                const count = await categories.count();
 
-                for (let index = 0; index < count; index += 1) {
-                    const category = categories.nth(index);
-                    const id =
-                        (
-                            await category.getAttribute('data-category-id')
-                        )?.trim() ?? '';
-                    const name =
-                        (
-                            await category
-                                .locator('.nav-item-label')
-                                .textContent()
-                        )?.trim() ?? '';
-                    const countText =
-                        (
-                            await category.locator('.item-count').textContent()
-                        )?.trim() ?? '';
-
-                    if (id && name && (Number.parseInt(countText, 10) || 0) > 0) {
-                        picked = { id, name };
-                        return true;
-                    }
+                if (category) {
+                    picked = { id: category.id, name: category.name };
+                    return true;
                 }
 
                 picked = null;
diff --git a/apps/electron-backend-e2e/src/category-management.e2e.ts b/apps/electron-backend-e2e/src/category-management.e2e.ts
index af7ae8137..eea9a1df4 100644
--- a/apps/electron-backend-e2e/src/category-management.e2e.ts
+++ b/apps/electron-backend-e2e/src/category-management.e2e.ts
@@ -16,6 +16,10 @@ import {
     waitForSourceRowIdle,
     waitForXtreamWorkspaceReady,
 } from './electron-test-fixtures';
+import {
+    readVisibleSidebarCategories,
+    readVisibleSidebarCategoryNames,
+} from './sidebar-categories.e2e-support';
 import { applyTheme } from './theme-contrast';
 
 test.describe('Electron Xtream Category Management', () => {
@@ -591,31 +595,6 @@ async function expectVisibleSidebarCategoryNames(
     }
 }
 
-async function readVisibleSidebarCategoryNames(page: Page): Promise<string[]> {
-    const categories = page.locator(
-        'app-workspace-context-panel .category-item'
-    );
-    const actualNames: string[] = [];
-    const count = await categories.count();
-
-    for (let index = 0; index < count; index += 1) {
-        const category = categories.nth(index);
-        if (!(await category.isVisible())) {
-            continue;
-        }
-
-        const categoryName =
-            (await category.locator('.nav-item-label').textContent())?.trim() ??
-            '';
-
-        if (categoryName) {
-            actualNames.push(categoryName);
-        }
-    }
-
-    return actualNames;
-}
-
 function stringArraysEqual(left: string[], right: string[]): boolean {
     return (
         left.length === right.length &&
@@ -634,35 +613,12 @@ async function pickSidebarCategory(
 
     await expect
         .poll(async () => {
-            const categories = page.locator(
-                'app-workspace-context-panel .category-item:visible'
+            const candidates = (
+                await readVisibleSidebarCategories(page)
+            ).filter(
+                (candidate) =>
+                    candidate.id && candidate.name && candidate.itemCount > 0
             );
-            const count = await categories.count();
-            const candidates: Array<{
-                id: string;
-                itemCount: number;
-                name: string;
-            }> = [];
-
-            for (let index = 0; index < count; index += 1) {
-                const category = categories.nth(index);
-                const id =
-                    (await category.getAttribute('data-category-id'))?.trim() ??
-                    '';
-                const name =
-                    (
-                        await category.locator('.nav-item-label').textContent()
-                    )?.trim() ?? '';
-                const countText =
-                    (
-                        await category.locator('.item-count').textContent()
-                    )?.trim() ?? '';
-                const itemCount = Number.parseInt(countText, 10) || 0;
-
-                if (id && name && itemCount > 0) {
-                    candidates.push({ id, itemCount, name });
-                }
-            }
 
             if (candidates.length === 0) {
                 preferredCandidate = null;
diff --git a/apps/electron-backend-e2e/src/sidebar-categories.e2e-support.ts b/apps/electron-backend-e2e/src/sidebar-categories.e2e-support.ts
new file mode 100644
index 000000000..9f4728465
--- /dev/null
+++ b/apps/electron-backend-e2e/src/sidebar-categories.e2e-support.ts
@@ -0,0 +1,43 @@
+import type { Page } from '@playwright/test';
+
+export interface SidebarCategorySnapshot {
+    id: string;
+    itemCount: number;
+    name: string;
+}
+
+const VISIBLE_SIDEBAR_CATEGORIES =
+    'app-workspace-context-panel .category-item:visible';
+
+/**
+ * Reads the visible sidebar categories in one DOM snapshot.
+ *
+ * Do not loop over `count()` with per-row `nth(index)` reads here: those
+ * locator calls auto-wait, so a row the sidebar removes between the count and
+ * the read (for example right after hiding categories) blocks the call until
+ * the surrounding `expect.poll` times out instead of letting the poll retry.
+ */
+export async function readVisibleSidebarCategories(
+    page: Page
+): Promise<SidebarCategorySnapshot[]> {
+    return page.locator(VISIBLE_SIDEBAR_CATEGORIES).evaluateAll((rows) =>
+        rows.map((row) => ({
+            id: row.getAttribute('data-category-id')?.trim() ?? '',
+            itemCount:
+                Number.parseInt(
+                    row.querySelector('.item-count')?.textContent?.trim() ?? '',
+                    10
+                ) || 0,
+            name:
+                row.querySelector('.nav-item-label')?.textContent?.trim() ?? '',
+        }))
+    );
+}
+
+export async function readVisibleSidebarCategoryNames(
+    page: Page
+): Promise<string[]> {
+    return (await readVisibleSidebarCategories(page))
+        .map((category) => category.name)
+        .filter(Boolean);
+}
diff --git a/docs/architecture/validation-map.md b/docs/architecture/validation-map.md
index 0ff903425..ff50576c9 100644
--- a/docs/architecture/validation-map.md
+++ b/docs/architecture/validation-map.md
@@ -181,6 +181,13 @@ and JSON summary output. CI uploads the merged Tier A report to Codecov with the
 Use atomized E2E targets when available, for example
 `pnpm nx run web-e2e:e2e-ci--src/xtream.e2e.ts`.
 
+Inside `expect.poll`, read a changing list in one DOM snapshot
+(`allTextContents()` or `evaluateAll()`, as in
+`apps/electron-backend-e2e/src/sidebar-categories.e2e-support.ts`), not by
+looping over `count()` with per-row `nth(index)` reads. Those reads auto-wait,
+so a row removed mid-loop hangs the predicate until the poll times out instead
+of letting it retry.
+
 Playwright coverage is measured semantically by tags and critical journeys, not
 by a source-line percentage. E2E reports should use tags such as `@critical`,
 `@electron`, `@web`, `@xtream`, `@stalker`, `@m3u`, `@search`, `@epg`,