diff --git a/apps/cli/sync.ts b/apps/cli/sync.ts
index c617604..d062262 100755
--- a/apps/cli/sync.ts
+++ b/apps/cli/sync.ts
@@ -45,11 +45,14 @@
  * segment — while the topic folder is a real segment
  * (`/tree-dfs/invert-binary-tree`), so a hand-written `index.mdx` in it is the
  * topic's landing page at `/tree-dfs` and Blume links the sidebar group row to
- * it. Sync never writes or moves an `index.mdx`, and never removes a folder
- * that still holds one. A phase folder's `meta.ts` is written once, when
- * missing, then hand-owned (its title is yours to rename); a topic's is
- * script-owned. An unplanned category group has no phase and sits at the
- * content root.
+ * it. The topic's problem pages sit one level down in a `(problems)` group,
+ * `tree-dfs/(problems)/226_invert-binary-tree.mdx`: no route segment either,
+ * and Blume strips the `<num>_` prefix from the route while sorting by it, so
+ * the URL is still `/tree-dfs/invert-binary-tree`. Sync never writes or moves
+ * an `index.mdx`, and never removes a folder that still holds one. A phase
+ * folder's `meta.ts` is written once, when missing, then hand-owned (its
+ * title is yours to rename); a topic's is script-owned. An unplanned category
+ * group has no phase and sits at the content root.
  *
  * Only the first-solve bucket is read: work/3 and work/7 hold blind re-solves
  * of problems whose page already exists (see work.ts), and a fresh scaffold
@@ -337,8 +340,9 @@ function phaseMeta(phase: Phase): string {
 
 /**
  * Blume folder meta for a topic: exact label (the folder slug loses `/` and
- * case), curriculum order, the sidebar icon, and `display: "group"` so the
- * topic collapses under its phase heading. An unplanned category group
+ * case), curriculum order, the sidebar icon, and `display: "page"` so the
+ * topic is one row under its phase heading that drills into its own panel
+ * (the landing page, then its `(problems)` list). An unplanned category group
  * (warm-ups) has no README number and sorts at 0, ahead of phase 1, so the
  * sidebar opens on the basics.
  */
@@ -347,7 +351,7 @@ function groupMeta(topic: Topic): string {
   if (!icon) console.warn(`no icon for group ${JSON.stringify(topic.name)}: add it to TOPIC_ICONS`);
   const fields = [`title: ${JSON.stringify(topic.name)}`, `order: ${topic.order ?? 0}`];
   if (icon) fields.push(`icon: ${JSON.stringify(icon)}`);
-  fields.push(`display: "group"`);
+  fields.push(`display: "page"`);
   return `import { defineMeta } from "blume";\n\nexport default defineMeta({ ${fields.join(", ")} });\n`;
 }
 
@@ -706,16 +710,16 @@ const tags = new Map<string, TopicTag>(); // every tag slug any problem page car
 for (const sol of ordered) {
   const langs = Object.keys(sol.code).sort().join("+");
   const workRef = `${sol.num}.${sol.slug} (${langs})`;
-  // (0N-<phase>)/<topic>/ folder (the topic is a real route segment, so its
-  // index.mdx is the landing page) + leetcode-number prefix: numeric sidebar
-  // order, prefix stripped from the URL.
+  // (0N-<phase>)/<topic>/(problems)/ folder (the topic is a real route segment,
+  // so its index.mdx is the landing page; `(problems)` adds none) +
+  // leetcode-number prefix: numeric sidebar order, prefix stripped from the URL.
   const topic = topics.get(sol.num) ?? topicByName.get(sol.category) ?? { name: sol.category };
   const dir = topicDir(topic);
   groups.set(dir, topic);
   if (topic.phase) phases.set(phaseDir(topic.phase), topic.phase);
-  const name = `${dir}/${sol.num}-${sol.slug}.mdx`;
+  const name = `${dir}/(problems)/${sol.num}_${sol.slug}.mdx`;
   const existing = pages.get(sol.num);
-  await mkdir(join(DOCS, dir), { recursive: true });
+  await mkdir(join(DOCS, dirname(name)), { recursive: true });
 
   let written: string; // the page as it stands after this run, for its topics
   if (existing) {