diff --git a/docker/frontend/scripts/library-check.mjs b/docker/frontend/scripts/library-check.mjs
index b7b85ff..5b32a25 100644
--- a/docker/frontend/scripts/library-check.mjs
+++ b/docker/frontend/scripts/library-check.mjs
@@ -374,11 +374,12 @@ await page.keyboard.press('Escape');
 step('escape closes the folder menu too', (await page.$('[data-key="lib-menu"]')) === null);
 
 // The head of the tree is the whole tree's control: a right click on the column's
-// own name folds every row that has something under it, so a roll read to the
-// bottom of its dates comes back to its own line. The frames in the strip are the
-// strip's business and do not move with it. The subfolder opened above carries a
-// fold of its own, so it is opened first: the claim is what ONE click does to
-// every row at once, not to the one that was already shut.
+// own name, or on the row of a folder picked at the top level, folds the folders
+// nested below the top level. The top-level row itself stays open — one click on
+// its name already shuts it, so the menu item would only repeat that click — and
+// the frames in the strip are the strip's business and do not move with the rows.
+// The subfolder opened above carries a fold of its own, so it is opened first:
+// the claim is what ONE click does to every row at once, not to one already shut.
 await page.click('[data-key="lib-node-CheckRoll/2026"]');
 await page.waitForFunction(() => document.querySelectorAll('[data-key^="lib-node-"]').length === 4, null, {
   timeout: 10_000,
@@ -407,29 +408,21 @@ step(
   await page.getAttribute('[data-key="lib-root-name"]', 'title')
 );
 await page.click('[data-key="lib-menu-collapse"]');
-await page.waitForFunction(() => document.querySelectorAll('[data-key^="lib-node-"]').length === 1, null, {
-  timeout: 10_000,
-  polling: 50,
-});
-const flatTiles = await page.$$eval(thumbs, (els) => els.length);
-const shutRoot = await page.getAttribute('[data-key="lib-node-CheckRoll"]', 'aria-expanded');
-// Opening the root back up is the ruler for the rest: only the rows the fold shut
-// are still away, and the subfolder two deep is one of them.
-await page.click('[data-key="lib-node-CheckRoll"]');
 await page.waitForFunction(() => document.querySelectorAll('[data-key^="lib-node-"]').length === 3, null, {
   timeout: 10_000,
   polling: 50,
 });
-const revealed = await page.$$eval('[data-key^="lib-node-"]', (els) => els.map((e) => e.dataset.key));
-step(
-  'and one click folds every row that has something under it',
-  deepRows === 4 && shutRoot === 'false' && flatTiles === deepTiles && revealed.join(',') === 'lib-node-CheckRoll,lib-node-CheckRoll/2026,lib-node-CheckRoll/Empty',
-  `${deepRows} rows → 1, ${revealed.length} back with the root opened, ${flatTiles} tiles kept`,
+const flatTiles = await page.$$eval(thumbs, (els) => els.length);
+const ended = await page.$$eval('[data-key^="lib-node-"]', (els) =>
+  els.map((e) => `${e.dataset.key}:${e.getAttribute('aria-expanded') ?? '-'}`)
+);
+step(
+  'and one click folds the subfolders, leaving the top-level row open',
+  deepRows === 4 &&
+    flatTiles === deepTiles &&
+    ended.join(' ') === 'lib-node-CheckRoll:true lib-node-CheckRoll/2026:false lib-node-CheckRoll/Empty:-',
+  `${deepRows} rows → ${ended.length}, ${ended.join(' ')}, ${flatTiles} tiles kept`,
 );
-// The open folder is the visit's, not the fold's, so it is put back where the
-// sections below left it.
-await page.click('[data-key="lib-node-CheckRoll/2026"]');
-await page.waitForFunction((sel) => document.querySelectorAll(sel).length === 2, thumbs, { timeout: 30_000 });
 
 // The divider drags the column, and what the visit leaves behind — the width the
 // column was left at and the folder that was open — is what the next visit opens
diff --git a/docker/frontend/src/Library.tsx b/docker/frontend/src/Library.tsx
index c121cc8..f352858 100644
--- a/docker/frontend/src/Library.tsx
+++ b/docker/frontend/src/Library.tsx
@@ -109,7 +109,7 @@ export function Library() {
   // right click landed on the empty part of the column, which is the way in for
   // one more folder; `root` means it landed on the head of a tree — the column's
   // own name, or the row of a folder picked at the top level — which carries
-  // folding every row that has something under it.
+  // folding the folders nested below the top level.
   const [menu, setMenu] = useState<{ folder: LibraryFolder | null; root?: boolean; x: number; y: number } | null>(null);
   // Where the drag of the column divider started, and how wide the column was
   // then — the pointer only ever reports a position, not a distance moved.
@@ -355,6 +355,11 @@ export function Library() {
     [nodes]
   );
 
+  // The folders nested below a top-level row — what COLLAPSE ALL has to fold. A
+  // top-level row is not one of them: it is its own fold, since one click on its
+  // name shuts it, so the menu item would only repeat the row's own click.
+  const nested = useMemo(() => new Set([...parents].filter((key) => key.includes('/'))), [parents]);
+
   // What the column draws: a folded row takes its whole subtree with it.
   const rows = useMemo(
     () =>
@@ -517,7 +522,7 @@ export function Library() {
                     {/* The column is titled with the folder the tree belongs to, so
                         a renamed roll is named where its frames are named. The name
                         is the whole tree's handle as well: one right click here
-                        folds every row that has something under it. */}
+                        folds the folders nested below the top level. */}
                     <b
                       className="lib-col-title"
                       data-key="lib-root-name"
@@ -566,9 +571,9 @@ export function Library() {
                           // act on the folder that was picked, so a right click on a
                           // subfolder row brings up its roll's menu. A row at the top
                           // level is a whole tree's head, so it also carries folding
-                          // the tree — the item the column's own name has, where a
-                          // reader actually right-clicks. Shift+F10 raises the same
-                          // event, which is the keyboard's way in.
+                          // what sits under it — the item the column's own name has,
+                          // where a reader actually right-clicks. Shift+F10 raises
+                          // the same event, which is the keyboard's way in.
                           onContextMenu={(e) => {
                             if (!folder) return;
                             e.preventDefault();
@@ -725,18 +730,18 @@ export function Library() {
       {menu ? (
         <div className="lib-menu" data-key="lib-menu" style={{ left: menu.x, top: menu.y }} onContextMenu={(e) => e.preventDefault()}>
           {/* Fold-the-tree leads the menu of a top-level row, and stands alone on
-              the column's own name: every row that has something under it goes,
-              so a long roll comes back to one line per folder and the click that
-              folds a row still opens it again one at a time. */}
+              the column's own name: the folders nested below the top level go,
+              one line per folder, and no top-level row ever leaves the column —
+              the row itself is one click away and its click already shuts it. */}
           {menu.root ? (
             <button
               type="button"
               className="lib-menu-item"
               data-key="lib-menu-collapse"
-              disabled={parents.size === 0}
+              disabled={nested.size === 0}
               onClick={() => {
                 setMenu(null);
-                setFolded(new Set(parents));
+                setFolded(new Set(nested));
               }}
             >
               {t('lib.collapseAll')}