diff --git a/apps/desktop/src/components/Sidebar.tsx b/apps/desktop/src/components/Sidebar.tsx
index 833e2c9f..50f87800 100644
--- a/apps/desktop/src/components/Sidebar.tsx
+++ b/apps/desktop/src/components/Sidebar.tsx
@@ -102,7 +102,6 @@ export function Sidebar({
 			}))}
 			folders={folders.map((folder) => ({
 				path: folder.path,
-				modifiedAt: folder.modified_at,
 			}))}
 			currentPath={currentPath ?? null}
 			sortMode={sortMode}
diff --git a/packages/ui/src/components/Sidebar.tsx b/packages/ui/src/components/Sidebar.tsx
index 8f6aae84..f8d74abd 100644
--- a/packages/ui/src/components/Sidebar.tsx
+++ b/packages/ui/src/components/Sidebar.tsx
@@ -1271,6 +1271,7 @@ export function Sidebar({
 			</DragOverlay>
 		</DndContext>
 	);
+	const sortLabel = sortMode === "recent" ? "Recent" : "Name";
 
 	return (
 		<SidebarFrame onCollapse={onCollapse} storageScope={storageScope}>
@@ -1313,8 +1314,8 @@ export function Sidebar({
 								<Button
 									variant="ghost"
 									size="icon-xs"
-									aria-label="Sort by..."
-									title="Sort by..."
+									aria-label={`Sort files: ${sortLabel}`}
+									title={`Sort files: ${sortLabel}`}
 								/>
 							}
 						>
@@ -1332,9 +1333,6 @@ export function Sidebar({
 								className="isolate z-50"
 							>
 								<Select.Popup className="z-50 w-36 origin-(--transform-origin) rounded-[var(--radius-popover)] border border-border bg-popover p-1 text-[11px] text-popover-foreground shadow-overlay outline-hidden transition-[transform,opacity] data-open:animate-in data-open:fade-in-0 data-open:zoom-in-95 data-closed:animate-out data-closed:fade-out-0 data-closed:zoom-out-95">
-									<p className="px-2 py-1 text-[10px] font-medium text-muted-foreground">
-										Sort by
-									</p>
 									<SortOption value="recent" label="Recent" />
 									<SortOption value="alpha" label="Name" />
 								</Select.Popup>
@@ -2441,7 +2439,13 @@ function stripMatchingExtension(name: string, extension: string) {
 		: name;
 }
 
-function SortOption({ value, label }: { value: string; label: string }) {
+function SortOption({
+	value,
+	label,
+}: {
+	value: SidebarSortMode;
+	label: string;
+}) {
 	return (
 		<Select.Item
 			value={value}
diff --git a/packages/ui/src/components/useSidebarTree.test.ts b/packages/ui/src/components/useSidebarTree.test.ts
index 30963206..ea368a54 100644
--- a/packages/ui/src/components/useSidebarTree.test.ts
+++ b/packages/ui/src/components/useSidebarTree.test.ts
@@ -10,6 +10,7 @@ import {
 	flattenRows,
 	type SidebarFile,
 	type SidebarRow,
+	type SidebarSortMode,
 	useSidebarTree,
 } from "./useSidebarTree";
 
@@ -43,10 +44,8 @@ function folderNames(node: ReturnType<typeof buildFileTree>) {
 
 describe("buildFileTree", () => {
 	it("includes empty folders from directory entries", () => {
-		const tree = buildFileTree(
-			[],
-			[{ path: "/workspace/empty", modifiedAt: 3 }],
-			(path) => path.replace("/workspace/", ""),
+		const tree = buildFileTree([], [{ path: "/workspace/empty" }], (path) =>
+			path.replace("/workspace/", ""),
 		);
 
 		expect(folderNames(tree)).toEqual(["empty"]);
@@ -56,10 +55,7 @@ describe("buildFileTree", () => {
 	it("includes folder-only nested hierarchies from directory entries", () => {
 		const tree = buildFileTree(
 			[],
-			[
-				{ path: "/workspace/parent", modifiedAt: 1 },
-				{ path: "/workspace/parent/child", modifiedAt: 2 },
-			],
+			[{ path: "/workspace/parent" }, { path: "/workspace/parent/child" }],
 			(path) => path.replace("/workspace/", ""),
 		);
 
@@ -83,10 +79,7 @@ describe("flattenRows", () => {
 		const getDisplayPath = (path: string) => path.replace("/workspace/", "");
 		const tree = buildFileTree(
 			[],
-			[
-				{ path: "/workspace/empty", modifiedAt: 1 },
-				{ path: "/workspace/empty/new-folder", modifiedAt: 2 },
-			],
+			[{ path: "/workspace/empty" }, { path: "/workspace/empty/new-folder" }],
 			getDisplayPath,
 		);
 
@@ -106,10 +99,7 @@ describe("flattenRows", () => {
 		const getDisplayPath = (path: string) => path.replace("/workspace/", "");
 		const tree = buildFileTree(
 			[],
-			[
-				{ path: "/workspace/empty", modifiedAt: 1 },
-				{ path: "/workspace/empty/new-folder", modifiedAt: 2 },
-			],
+			[{ path: "/workspace/empty" }, { path: "/workspace/empty/new-folder" }],
 			getDisplayPath,
 		);
 
@@ -123,6 +113,101 @@ describe("flattenRows", () => {
 
 		expect(rows.map((row) => row.label)).toEqual(["empty/new-folder"]);
 	});
+
+	it.each([
+		["recent", ["alpha.md", "charlie.md", "bravo.md"]],
+		["alpha", ["alpha.md", "bravo.md", "charlie.md"]],
+	] satisfies [
+		SidebarSortMode,
+		string[],
+	][])("sorts files by %s", (sortMode, expected) => {
+		const files = [
+			{ path: "/workspace/alpha.md", modifiedAt: 30 },
+			{ path: "/workspace/bravo.md", modifiedAt: 10 },
+			{ path: "/workspace/charlie.md", modifiedAt: 20 },
+		];
+		const tree = buildFileTree(files, [], getDisplayPath);
+
+		const rows = flattenRows({
+			files,
+			getDisplayPath,
+			tree,
+			sortMode,
+			expandedFolders: new Set(),
+		});
+
+		expect(fileLabels(rows)).toEqual(expected);
+	});
+
+	it.each([
+		"recent",
+		"alpha",
+	] satisfies SidebarSortMode[])("keeps folders alphabetical at every depth with %s file order", (sortMode) => {
+		const files = [
+			{ path: "/workspace/02 Stuff/new.md", modifiedAt: 30 },
+			{ path: "/workspace/00 Index/old.md", modifiedAt: 10 },
+		];
+		const folders = [
+			{ path: "/workspace/Parent/02 Stuff" },
+			{ path: "/workspace/Parent/00 Index" },
+			{ path: "/workspace/02 Stuff" },
+			{ path: "/workspace/00 Index" },
+			{ path: "/workspace/Parent" },
+		];
+		const tree = buildFileTree(files, folders, getDisplayPath);
+
+		const rows = flattenRows({
+			files,
+			getDisplayPath,
+			tree,
+			sortMode,
+			expandedFolders: new Set(["Parent/"]),
+		});
+
+		expect(folderLabels(rows, 0)).toEqual(["00 Index", "02 Stuff", "Parent"]);
+		expect(folderLabels(rows, 1)).toEqual(["00 Index", "02 Stuff"]);
+	});
+
+	it("sorts numeric names naturally", () => {
+		const files = [
+			{ path: "/workspace/10 Notes.md" },
+			{ path: "/workspace/2 Notes.md" },
+		];
+		const tree = buildFileTree(
+			files,
+			[{ path: "/workspace/10 Archive" }, { path: "/workspace/2 Archive" }],
+			getDisplayPath,
+		);
+
+		const rows = flattenRows({
+			files,
+			getDisplayPath,
+			tree,
+			sortMode: "alpha",
+			expandedFolders: new Set(),
+		});
+
+		expect(folderLabels(rows, 0)).toEqual(["2 Archive", "10 Archive"]);
+		expect(fileLabels(rows)).toEqual(["2 Notes.md", "10 Notes.md"]);
+	});
+
+	it("uses the selected file order for pinned files", () => {
+		const files = [
+			{ path: "/workspace/alpha.md", modifiedAt: 10, pinned: true },
+			{ path: "/workspace/bravo.md", modifiedAt: 30, pinned: true },
+		];
+		const tree = buildFileTree(files, [], getDisplayPath);
+
+		const rows = flattenRows({
+			files,
+			getDisplayPath,
+			tree,
+			sortMode: "recent",
+			expandedFolders: new Set(),
+		});
+
+		expect(fileLabels(rows)).toEqual(["bravo.md", "alpha.md"]);
+	});
 });
 
 describe("useSidebarTree", () => {
@@ -211,6 +296,16 @@ function filePaths(rows: SidebarRow[]) {
 	return rows.flatMap((row) => (row.kind === "file" ? [row.file.path] : []));
 }
 
+function fileLabels(rows: SidebarRow[]) {
+	return rows.flatMap((row) => (row.kind === "file" ? [row.label] : []));
+}
+
+function folderLabels(rows: SidebarRow[], depth: number) {
+	return rows.flatMap((row) =>
+		row.kind === "folder" && row.depth === depth ? [row.label] : [],
+	);
+}
+
 function folderRow(rows: SidebarRow[], id: string) {
 	const row = rows.find((row) => row.kind === "folder" && row.id === id);
 	if (!row || row.kind !== "folder") throw new Error(`Missing folder ${id}`);
diff --git a/packages/ui/src/components/useSidebarTree.ts b/packages/ui/src/components/useSidebarTree.ts
index 745aac92..b639d269 100644
--- a/packages/ui/src/components/useSidebarTree.ts
+++ b/packages/ui/src/components/useSidebarTree.ts
@@ -11,13 +11,11 @@ export type SidebarFile = {
 
 export type SidebarFolder = {
 	path: string;
-	modifiedAt?: number;
 };
 
 type FolderNode = {
 	id: string;
 	name: string;
-	modifiedAt: number;
 	folders: Map<string, FolderNode>;
 	files: SidebarFile[];
 };
@@ -157,7 +155,6 @@ function makeFolder(id: string, name: string): FolderNode {
 	return {
 		id,
 		name,
-		modifiedAt: 0,
 		folders: new Map(),
 		files: [],
 	};
@@ -175,10 +172,8 @@ export function buildFileTree(
 		if (!displayPath) continue;
 		const segments = displayPath.split("/").filter(Boolean);
 		let parent = root;
-		const modifiedAt = folderEntry.modifiedAt ?? 0;
 		for (const segment of segments) {
 			const folder = ensureFolder(parent, segment);
-			folder.modifiedAt = Math.max(folder.modifiedAt, modifiedAt);
 			parent = folder;
 		}
 	}
@@ -194,7 +189,6 @@ export function buildFileTree(
 		const modifiedAt = file.modifiedAt ?? 0;
 		for (const segment of segments) {
 			const folder = ensureFolder(parent, segment);
-			folder.modifiedAt = Math.max(folder.modifiedAt, modifiedAt);
 			parent = folder;
 		}
 
@@ -203,7 +197,6 @@ export function buildFileTree(
 			path: file.path,
 			modifiedAt,
 		});
-		parent.modifiedAt = Math.max(parent.modifiedAt, modifiedAt);
 	}
 
 	return root;
@@ -268,9 +261,7 @@ function appendFolderChildren(
 	rows: SidebarRow[],
 	uncompactFolderId: string | null,
 ) {
-	const folders = [...folder.folders.values()].sort((a, b) =>
-		compareNodes(a, b, sortMode),
-	);
+	const folders = [...folder.folders.values()].sort(compareFolders);
 	const files = [...folder.files].sort((a, b) => compareFiles(a, b, sortMode));
 
 	for (const child of folders) {
@@ -333,16 +324,8 @@ function compactFolder(
 	return { folder: cursor, label: names.join("/"), segments };
 }
 
-function compareNodes(
-	a: Pick<FolderNode, "name" | "modifiedAt">,
-	b: Pick<FolderNode, "name" | "modifiedAt">,
-	sortMode: SidebarSortMode,
-) {
-	if (sortMode === "recent") {
-		const byModified = b.modifiedAt - a.modifiedAt;
-		if (byModified !== 0) return byModified;
-	}
-	return a.name.localeCompare(b.name);
+function compareFolders(a: FolderNode, b: FolderNode) {
+	return compareNames(a.name, b.name);
 }
 
 function compareFiles(
@@ -350,11 +333,23 @@ function compareFiles(
 	b: SidebarFile,
 	sortMode: SidebarSortMode,
 ) {
+	const byName = compareNames(
+		fileNameFromPath(a.path),
+		fileNameFromPath(b.path),
+	);
 	if (sortMode === "recent") {
-		const byModified = (b.modifiedAt ?? 0) - (a.modifiedAt ?? 0);
-		if (byModified !== 0) return byModified;
+		return (b.modifiedAt ?? 0) - (a.modifiedAt ?? 0) || byName;
 	}
-	return fileNameFromPath(a.path).localeCompare(fileNameFromPath(b.path));
+	return byName;
+}
+
+const nameCollator = new Intl.Collator(undefined, {
+	numeric: true,
+	sensitivity: "base",
+});
+
+function compareNames(a: string, b: string) {
+	return nameCollator.compare(a, b) || a.localeCompare(b);
 }
 
 function getFolderAncestorIds(displayPath: string): Set<string> {