fix(windows): preserve native drive-root probes

packages/session-persistence/session-persistence-jsonl/src/win32.ts

@@ -91,7 +91,10 @@ function isEEXIST(error: unknown): boolean {
 
 async function assertDirectory(path: string): Promise<boolean> {
   try {
-    const info = await stat(toNamespacedPath(path))
+    // A bare drive root is already short, and Node rejects its extended-length
+    // spelling as EISDIR. Descendants retain the namespace for long-path probes.
+    const probe = path === parse(path).root ? path : toNamespacedPath(path)
+    const info = await stat(probe)
     if (info.isDirectory()) return true
     const error = new Error(`path exists but is not a directory: ${path}`) as NodeJS.ErrnoException
     error.code = 'ENOTDIR'

packages/session-persistence/session-persistence-jsonl/tests/win32.spec.ts

@@ -92,11 +92,43 @@ async function importWithFilesystemMove(): Promise<typeof import('../src/win32.t
 
 afterEach(async () => {
   vi.doUnmock('koffi')
+  vi.doUnmock('node:fs/promises')
+  vi.doUnmock('node:path')
   vi.resetModules()
   for (const root of roots.splice(0)) await rm(root, { recursive: true, force: true })
 })
 
 describe('Windows durable namespace helpers', () => {
+  it('keeps drive-root probes native while namespacing descendants', async () => {
+    const probes: string[] = []
+    vi.resetModules()
+    vi.doMock('node:fs/promises', async (importOriginal) => {
+      const actual = await importOriginal<typeof import('node:fs/promises')>()
+      return {
+        ...actual,
+        stat: async (path: string) => {
+          probes.push(path)
+          return { isDirectory: () => true }
+        },
+      }
+    })
+    vi.doMock('node:path', async (importOriginal) => {
+      const actual = await importOriginal<typeof import('node:path')>()
+      return {
+        ...actual,
+        join: (...paths: string[]) => actual.win32.join(...paths),
+        parse: (path: string) => actual.win32.parse(path),
+        resolve: (...paths: string[]) => actual.win32.resolve(...paths),
+        toNamespacedPath: (path: string) => actual.win32.toNamespacedPath(path),
+      }
+    })
+    const { ensureDurableDirectoryWin32 } = await import('../src/win32.ts')
+
+    await ensureDurableDirectoryWin32('C:\\existing')
+
+    expect(probes).toEqual(['C:\\', '\\\\?\\C:\\existing'])
+  })
+
   it('publishes a new file with write-through MoveFileExW semantics', async () => {
     const { publishNewFileWin32 } = await importWithFilesystemMove()
     const root = await tempRoot()