Desktop: new session page has no file tree (button absent) with New layout designs enabled

Description

When creating a new session in the OpenCode Desktop app, the file tree cannot be shown at all. There is no file tree button anywhere on the new-session screen.

With New layout designs enabled (the default), the desktop /new-session page renders only the prompt composer. The file tree (and its toggle button) do not exist on this page — not in the titlebar, not in the side panel. Expected: a way to open the file tree / project explorer for the session (button, toggle, or sidebar), like the old layout.

Repro

1. Open OpenCode Desktop (latest, v1.18.x).
2. Keep New layout designs enabled (default).
3. Click "New session" (app routes to /new-session).
4. Look for the file tree / project explorer or its toggle button.

Expected: file tree accessible (button visible or panel in the sidebar).
Actual: no file tree button exists at all; nothing to open the file tree.

Impact

Users on the new layout cannot browse the project in a session, making file references and navigation much harder.

Related

• #33119 — Desktop new-session page cannot toggle terminal (same class of issue: /new-session draft page renders only the prompt composer, missing panels mounted on the real session route)
• #29951 — Advanced settings toggles for desktop toolbar buttons do nothing in new layout (V2 titlebar missing file-tree button)
• #34223 — File tree toggle hidden by desktop() gate in settings, panel not open by default
• PR #34828 — "fix(app): add file tree toggle to new session header" (appears related; user still cannot see it on latest release)

Environment

• OpenCode Desktop version: latest (v1.18.16)
• OS: Windows 11 64-bit
• Layout: New layout designs enabled (default)