{# COLUMNS 2 + 3 — the project-scoped region (agents column + center). Swapped together by GET /projects/{key} on a project switch (and the center's own 10s poll). Carries data-selected-key on its root so the rail re-syncs its active highlight after the swap. The FILE PANE OVERLAY (#ws-editor-overlay) is a SIBLING of #center-region — it slides in from the right and covers the center, while the agent-detail / dashboard stay mounted underneath (the center is never swapped out, so its state is preserved and restored on close). It lives here (not in console.html) so a project switch — which re-renders this scope and re-roots the col-4 worktree — also resets the pane to closed. Clicking a tree file loads its preview body into #ws-editor-body and slides this in (openWsFile); the body carries its own header (icon · path · Edit/Save · ✕). #}