fix(sessions): keep missing-worktree relocation manual

Remove automatic moves on session activation, terminal failures, and archive restoration while preserving manual moves and worktree deletion.

Replace directory listing probes with a stat-only endpoint using Node built-ins, including an isolated module-load regression test for packaged desktop.

Validation: focused session, worktree, filesystem, localization, and bridge tests; workspace type-check and lint; web and VS Code builds. Desktop startup and behavior verified by the maintainer.

packages/vscode/src/DOCUMENTATION.md

@@ -49,6 +49,7 @@ The webview build emits each worker as one self-contained file. VS Code webviews
 
 - `bridge-localfs-proxy-runtime.ts`
   - Local `/api/fs/read` and `/api/fs/raw` proxy helpers and shared proxy utility helpers.
+  - `/api/fs/directory-stat` returns 501 locally. Directory-availability probes remain unknown in VS Code rather than falling through to OpenCode.
   - Workspace-contained Markdown gallery images use these local filesystem
     routes without calling the server grant route. Grant requests for OpenCode
     temporary-directory images return an explicit unsupported response instead

packages/vscode/src/bridge-localfs-proxy-runtime.test.js

@@ -61,6 +61,11 @@ describe('bridge local fs proxy', () => {
     expect(response?.status).toBe(404);
   });
 
+  it('does not forward directory availability probes to OpenCode', async () => {
+    const response = await tryHandleLocalFsProxy('GET', '/api/fs/directory-stat?path=%2Fmissing-dir');
+    expect(response?.status).toBe(501);
+  });
+
   it('reads from the active directory when it is the second workspace root', async () => {
     existingFiles.add('/workspace-two/image.png');
     const response = await tryHandleLocalFsProxy(

packages/vscode/src/bridge-localfs-proxy-runtime.ts

@@ -56,6 +56,9 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
   }
 
   const fsProxyPath = normalizeFsProxyPath(parsed.pathname);
+  if (parsed.pathname === '/api/fs/directory-stat') {
+    return buildProxyJsonError(501, 'Directory availability probes are not supported in the VS Code runtime');
+  }
   if (/^\/api\/openchamber\/sessions\/[^/]+\/markdown-image-grants$/.test(parsed.pathname)) {
     return buildProxyJsonError(501, 'Markdown image grants are not supported in the VS Code runtime');
   }