diff --git a/scripts/workspace-package-globs.spec.ts b/scripts/workspace-package-globs.spec.ts
new file mode 100644
index 0000000000..1a8bebf075
--- /dev/null
+++ b/scripts/workspace-package-globs.spec.ts
@@ -0,0 +1,13 @@
+/** Windows manifest paths still select the packages whose artifacts Desktop bundles. */
+import { globSync } from 'node:fs'
+import { resolve, win32 } from 'node:path'
+import { expect, it } from 'vitest'
+import { workspacePackageGlobs } from './workspace-package-globs.ts'
+
+it('selects workspace packages from Windows and POSIX manifest paths', () => {
+  const cwd = resolve(import.meta.dirname, '..')
+  const manifests = ['packages\\util\\atomic-write\\package.json', 'vendor/cordis/package.json']
+  const selected = globSync(workspacePackageGlobs(manifests), { cwd }).map(path => path.replaceAll('\\', '/')).sort()
+  expect(selected).toEqual(['packages/util/atomic-write', 'vendor/cordis'])
+  expect(globSync(manifests.map(path => win32.dirname(path)), { cwd })).toEqual([])
+})
diff --git a/scripts/workspace-package-globs.ts b/scripts/workspace-package-globs.ts
new file mode 100644
index 0000000000..dc1d597bff
--- /dev/null
+++ b/scripts/workspace-package-globs.ts
@@ -0,0 +1,11 @@
+/** Convert discovered package manifests into portable bundler workspace patterns. */
+import { posix } from 'node:path'
+
+/**
+ * Keep filesystem separators from becoming escapes in workspace globs.
+ * @param manifests - Repository-relative manifest paths returned by filesystem discovery.
+ * @returns Package directory patterns using forward slashes on every host.
+ */
+export function workspacePackageGlobs(manifests: readonly string[]): string[] {
+  return manifests.map(path => posix.dirname(path.replaceAll('\\', '/')))
+}
diff --git a/tsdown.config.ts b/tsdown.config.ts
index 7dc713a8e8..b66a197ef1 100644
--- a/tsdown.config.ts
+++ b/tsdown.config.ts
@@ -1,8 +1,8 @@
 import { globSync } from 'node:fs'
-import { dirname } from 'node:path'
 import { defineConfig } from 'tsdown'
 import { typertPlugin } from './packages/typert/generator/lib/types/tsdown-plugin.js'
 import { WORKSPACE_TYPERT_FACES } from './scripts/typert-faces.ts'
+import { workspacePackageGlobs } from './scripts/workspace-package-globs.ts'
 
 function isBuildFaceClient(value: unknown): boolean {
   if (value === undefined || value === 'host') return false
@@ -21,7 +21,7 @@ function isBuildFaceClient(value: unknown): boolean {
  */
 export default defineConfig(({ env }) => {
   const client = isBuildFaceClient(env?.DSH_BUILD_FACE)
-  const packages = globSync(['vendor/*/package.json', 'packages/*/*/package.json'], { cwd: import.meta.dirname }).map(dirname)
+  const packages = workspacePackageGlobs(globSync(['vendor/*/package.json', 'packages/*/*/package.json'], { cwd: import.meta.dirname }))
   return {
     workspace: [...packages, 'apps/cli', ...client ? [] : ['apps/desktop-host']],
     entry: client ? '' : ['lib/types/{index,startup}.js'],