diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 4a2a1e2..90634bc 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -72,16 +72,17 @@ jobs:
             <(grep -E '^[A-Za-z0-9_.-]+==' /tmp/requirements-lock.txt | sort)
 
   # ── Unit tests: matrix across OS and Python version ───────────────────────
-  # Closes #13. The unittest suite is the merge gate. Multi-OS catches the
-  # rare path / line-ending issue that a single-OS run hides; multi-Python
-  # catches API drift across LTS / current / latest interpreters.
+  # Closes #13 and #44. Multi-OS catches path-normalisation drift and
+  # line-ending issues that a single-OS run hides; multi-Python catches API
+  # drift across LTS / current / latest interpreters. Matrix parallelism
+  # keeps wall-clock under ~15 min (slowest runner wins, not the sum).
   unittest:
     name: Unit tests (${{ matrix.os }} / Python ${{ matrix.python-version }})
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, windows-latest, macos-latest]
         python-version: ["3.10", "3.11", "3.12", "3.13"]
     steps:
       # Pinned to immutable commit SHAs (not @v4 / @v5) so a compromised tag
@@ -117,6 +118,21 @@ jobs:
         # ~2× the CI minutes for zero extra signal.
         run: python -m pytest tests/test_api_endpoints.py -v --tb=short
 
+      # ── PyInstaller desktop build (Windows only, once per workflow) ────────
+      # Closes #44. Builds the onedir bundle and smoke-tests --help so the
+      # desktop entry point is verified without launching the GUI window.
+      - name: Install PyInstaller
+        if: matrix.os == 'windows-latest' && matrix.python-version == '3.12'
+        run: python -m pip install 'pyinstaller>=6,<7'
+
+      - name: Build PyInstaller bundle
+        if: matrix.os == 'windows-latest' && matrix.python-version == '3.12'
+        run: pyinstaller cursor-browser.spec --noconfirm
+
+      - name: Smoke-test PyInstaller exe (--help)
+        if: matrix.os == 'windows-latest' && matrix.python-version == '3.12'
+        run: dist\CursorChatBrowser\CursorChatBrowser.exe --help
+
   # ── Typecheck: mypy ───────────────────────────────────────────────────────
   # Codebase already has type hints across most of the surface (~70+ typed
   # functions). Mypy runs in lenient mode (--ignore-missing-imports for
diff --git a/launcher.py b/launcher.py
index fbfefac..8c70c12 100644
--- a/launcher.py
+++ b/launcher.py
@@ -5,10 +5,24 @@
 directly in-process.
 """
 
+from __future__ import annotations
+
+import argparse
+import sys
+
 from app import create_app
 
 
-def main():
+def main(argv: list[str] | None = None) -> None:
+    parser = argparse.ArgumentParser(
+        prog="cursor-chat-browser",
+        description=(
+            "Cursor Chat Browser - opens the Flask app in a native OS window "
+            "via pywebview (no HTTP server or port)."
+        ),
+    )
+    parser.parse_args(argv)
+
     try:
         import webview
     except ImportError:
@@ -28,4 +42,4 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    main(sys.argv[1:])
diff --git a/tests/test_normalize_file_path.py b/tests/test_normalize_file_path.py
index b3531fa..90d9274 100644
--- a/tests/test_normalize_file_path.py
+++ b/tests/test_normalize_file_path.py
@@ -1,13 +1,15 @@
-"""Tests for utils.path_helpers path/timestamp helpers (closes #46).
+"""Tests for utils.path_helpers path/timestamp helpers (closes #44, #46).
 
 Covers ``normalize_file_path`` and ``to_epoch_ms``, both previously duplicated
 in scripts/export.py. All call-sites in the web app and CLI export script now
 use the shared implementations in utils.path_helpers.
 
-Test inventory (this module only): 21 cases — 12 ``normalize_file_path``,
+Test inventory (this module only): 23 cases — 14 ``normalize_file_path``,
 9 ``to_epoch_ms``. On win32, 2 cases skip (POSIX passthrough in
-``TestNormalizeFilePathPosixPassthrough`` only). A full-suite run may report
-more skips (e.g. ``skipped=4``) from other test modules, not this file.
+``TestNormalizeFilePathPosixPassthrough`` only). On non-win32, 2 cases skip
+(``TestNormalizeFilePathWindowsNative`` — exercised on windows-latest CI).
+A full-suite run may report more skips (e.g. ``skipped=4``) from other test
+modules, not this file.
 """
 
 import sys
@@ -91,6 +93,20 @@ def test_mixed_case_drive_lowercased(self) -> None:
         self.assertEqual(out, r"e:\mixed\case\path")
 
 
+class TestNormalizeFilePathWindowsNative(unittest.TestCase):
+    """Win32-only edge cases — run on actual Windows runners in CI (#44)."""
+
+    @unittest.skipUnless(sys.platform == "win32", "native win32 path semantics")
+    def test_leading_backslash_before_drive_stripped(self) -> None:
+        out = normalize_file_path(r"\C:\Users\Dev\project")
+        self.assertEqual(out, r"c:\users\dev\project")
+
+    @unittest.skipUnless(sys.platform == "win32", "native win32 path semantics")
+    def test_file_uri_backslashes_normalised(self) -> None:
+        out = normalize_file_path(r"file:///C:\Users\Dev\project")
+        self.assertEqual(out, r"c:\users\dev\project")
+
+
 class TestNormalizeFilePathPosixPassthrough(unittest.TestCase):
     def test_plain_posix_path_unchanged_on_non_windows(self) -> None:
         if sys.platform == "win32":