diff --git a/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.test.tsx b/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.test.tsx
index b14b609c8..2424544c4 100644
--- a/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.test.tsx
+++ b/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.test.tsx
@@ -205,14 +205,15 @@ describe("binary and decoding helpers", () => {
 });
 
 describe("buildTreeInputs", () => {
-  test("emits placeholders for directories so they appear in the tree", () => {
+  test("emits native directory paths without user-visible placeholders", () => {
     const entries: SandboxFileEntry[] = [
       { name: "src", is_dir: true },
       { name: "package.json", is_dir: false, size: 200 },
     ];
     const inputs = buildTreeInputs(entries);
+    expect(inputs.paths).toContain("src/");
     expect(inputs.paths).toContain("package.json");
-    expect(inputs.paths.some((path) => path.startsWith("src/"))).toBe(true);
+    expect(inputs.paths).not.toContain("src/__fabro_dir__");
     expect(inputs.directories.has("src")).toBe(true);
     expect(inputs.fileEntries.get("package.json")?.size).toBe(200);
   });
@@ -225,9 +226,8 @@ describe("classifySelection", () => {
   ];
   const inputs = buildTreeInputs(entries);
 
-  test("recognizes a placeholder selection as a directory", () => {
-    const placeholder = inputs.paths.find((path) => path.startsWith("src/"))!;
-    expect(classifySelection(placeholder, inputs.fileEntries, inputs.directories)).toEqual({
+  test("recognizes a native directory path selection as a directory", () => {
+    expect(classifySelection("src/", inputs.fileEntries, inputs.directories)).toEqual({
       kind:         "dir",
       relativePath: "src",
     });
@@ -363,11 +363,11 @@ describe("FilesystemPanel render", () => {
     };
     renderPanel();
     expect(lastFilesArgs?.path).toBe("/");
-    const placeholder = filesystemPanelModule.buildTreeInputs(
+    const directoryPath = filesystemPanelModule.buildTreeInputs(
       filesState.data!.data,
-    ).paths.find((path) => path.startsWith("src/"))!;
+    ).paths.find((path) => path === "src/")!;
     act(() => {
-      lastTreeOptions?.onSelectionChange?.([placeholder]);
+      lastTreeOptions?.onSelectionChange?.([directoryPath]);
     });
     expect(lastFilesArgs?.path).toBe("/src");
   });
diff --git a/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.tsx b/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.tsx
index 835920a19..aa4bd39dd 100644
--- a/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.tsx
+++ b/apps/fabro-web/app/routes/run-sandbox/filesystem-panel.tsx
@@ -142,9 +142,8 @@ interface BuiltTreeInputs {
 
 // The list endpoint returns flat names like `foo` (depth=1) or `foo/bar.ts`
 // (depth=2). We feed those names to @pierre/trees as relative paths. Every
-// directory gets a synthetic placeholder child so empty directories still
-// appear; the placeholders are filtered out before selection.
-const DIRECTORY_PLACEHOLDER = "__fabro_dir__";
+// directories are represented with the tree library's canonical trailing-slash
+// form so empty directories appear without synthetic child rows.
 
 export function buildTreeInputs(entries: readonly SandboxFileEntry[]): BuiltTreeInputs {
   const paths: string[] = [];
@@ -154,7 +153,7 @@ export function buildTreeInputs(entries: readonly SandboxFileEntry[]): BuiltTree
   for (const entry of entries) {
     if (entry.is_dir) {
       directories.add(entry.name);
-      paths.push(`${entry.name}/${DIRECTORY_PLACEHOLDER}`);
+      paths.push(`${entry.name}/`);
     } else {
       fileEntries.set(entry.name, entry);
       paths.push(entry.name);
@@ -164,8 +163,8 @@ export function buildTreeInputs(entries: readonly SandboxFileEntry[]): BuiltTree
   return { paths, fileEntries, directories };
 }
 
-function isPlaceholderPath(path: string): boolean {
-  return path.endsWith(`/${DIRECTORY_PLACEHOLDER}`) || path === DIRECTORY_PLACEHOLDER;
+function normalizeDirectorySelection(path: string): string {
+  return path.replace(/\/+$/, "");
 }
 
 export function classifySelection(
@@ -173,19 +172,15 @@ export function classifySelection(
   fileEntries: Map<string, SandboxFileEntry>,
   directories: Set<string>,
 ): { kind: "file"; entry: SandboxFileEntry } | { kind: "dir"; relativePath: string } | null {
-  if (isPlaceholderPath(selectedPath)) {
-    const relPath = selectedPath.substring(0, selectedPath.length - DIRECTORY_PLACEHOLDER.length - 1);
-    if (relPath) return { kind: "dir", relativePath: relPath };
-    return null;
-  }
   const fileEntry = fileEntries.get(selectedPath);
   if (fileEntry) return { kind: "file", entry: fileEntry };
-  if (directories.has(selectedPath)) {
-    return { kind: "dir", relativePath: selectedPath };
+  const directoryPath = normalizeDirectorySelection(selectedPath);
+  if (directories.has(directoryPath)) {
+    return { kind: "dir", relativePath: directoryPath };
   }
   // Intermediate directory implied by a nested path (depth>1). Treat selection
   // as navigation into that subdir.
-  return { kind: "dir", relativePath: selectedPath };
+  return { kind: "dir", relativePath: directoryPath };
 }
 
 interface PreviewState {