Add Windows support

Windows joins the three systems as its own entry in each table: DirectShow
through ffmpeg for capture, the Win32 clipboard and SendInput for the paste,
RegisterHotKey for the global shortcut, and the whisper.cpp and llama.cpp
Windows zips (the OpenBLAS whisper build, which transcribes about twice as
fast on a plain CPU). Settings go to APPDATA, data to LOCALAPPDATA, and
install.ps1 adds the Start Menu entry, the dikte command and an optional
autostart. Meetings are not supported yet: Windows offers nothing to record
the far side from.

Porting surfaced three fixes that were not Windows specific:

- A stopped or overlong download tried to delete its .part file while still
  holding it open, which Windows refuses. The unlinks now wait for the handle.
- The CLI transcribed files without handing the local servers their settings
  first, so a local provider failed with "no model downloaded" wherever the
  GUI had not run in the same process.
- The audio content types are pinned instead of asked of the registry, which
  answers differently machine to machine.

One fix is Windows specific but sits in shared code: shutdown() does not end
a blocked recv there, so stopping a request also closes the socket handle.

Co-Authored-By: Claude Fable 5 <[email protected]>

tests/test_ggml.py

@@ -15,6 +15,7 @@ import tarfile
 import textwrap
 import threading
 import time
+import zipfile
 from unittest import mock
 
 import ggml
@@ -77,6 +78,15 @@ def tarball(entries):
     return buf.getvalue()
 
 
+def zipball(entries):
+    """A .zip laid out the way the Windows releases are."""
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, "w") as bundle:
+        for name, content in entries.items():
+            bundle.writestr(name, content)
+    return buf.getvalue()
+
+
 class Local(DikteTest):
     """A test with its own bin, models and cache directories."""
 
@@ -681,3 +691,78 @@ class Sizes(DikteTest):
         self.assertEqual(ggml.human_size(512), "512 B")
         self.assertEqual(ggml.human_size(574041195), "547.4 MB")
         self.assertEqual(ggml.human_size(3_095_033_483), "2.9 GB")
+
+
+# --- Windows ----------------------------------------------------------------
+
+
+class WindowsAssets(Local):
+    """Which archive a Windows machine is handed."""
+
+    def setUp(self):
+        super().setUp()
+        self.patch_attr(sys, "platform", "win32")
+        self.patch_attr(ggml, "_arch", lambda: "x64")
+
+    def test_whisper_prefers_the_blas_build(self):
+        # On a plain CPU it transcribes about twice as fast as the stock one.
+        self.assertEqual(ggml._wanted_assets(ggml.WHISPER),
+                         ("whisper-blas-bin-x64.zip", "whisper-bin-x64.zip"))
+
+    def test_llama_takes_the_vulkan_build_when_there_is_a_loader(self):
+        self.patch_attr(ggml, "_has_vulkan", lambda: True)
+        self.assertEqual(ggml._wanted_assets(ggml.LLAMA),
+                         ("bin-win-vulkan-x64.zip", "bin-win-cpu-x64.zip"))
+
+    def test_llama_falls_back_to_the_cpu_build_without_one(self):
+        self.patch_attr(ggml, "_has_vulkan", lambda: False)
+        self.assertEqual(ggml._wanted_assets(ggml.LLAMA),
+                         ("bin-win-cpu-x64.zip",))
+
+    def test_an_arm_machine_is_not_handed_the_x64_build(self):
+        self.patch_attr(ggml, "_arch", lambda: "arm64")
+        self.patch_attr(ggml, "_has_vulkan", lambda: True)
+        self.assertEqual(ggml._wanted_assets(ggml.LLAMA),
+                         ("bin-win-cpu-arm64.zip",))
+
+
+class InstallOnWindows(Local):
+    """The Windows releases are zips, and the binary carries .exe."""
+
+    def setUp(self):
+        super().setUp()
+        self.patch_attr(sys, "platform", "win32")
+        self.patch_attr(ggml, "_arch", lambda: "x64")
+        self.archive = zipball({
+            "Release/whisper-server.exe": b"MZ not really a program",
+            "Release/whisper.dll": b"not really a library",
+        })
+
+    def release(self, *names):
+        digest = hashlib.sha256(self.archive)
+        return {"tag_name": "v1.9.1", "assets": [
+            {"name": name, "browser_download_url": f"https://example.invalid/{name}",
+             "size": 10, "digest": "sha256:" + digest.hexdigest()}
+            for name in names]}
+
+    def test_the_zip_lands_and_the_exe_inside_it_is_found(self):
+        with serving(self.release("whisper-blas-bin-x64.zip"), self.archive):
+            path = ggml.install_program(ggml.WHISPER)
+        self.assertTrue(path.endswith("whisper-server.exe"))
+        self.assertTrue(os.path.isfile(path))
+        self.assertTrue(os.path.isfile(os.path.join(os.path.dirname(path),
+                                                    "whisper.dll")))
+        self.assertEqual(ggml.installed_program(ggml.WHISPER), path)
+
+    def test_the_blas_build_is_the_one_fetched_when_both_are_offered(self):
+        listing = self.release("whisper-bin-x64.zip", "whisper-blas-bin-x64.zip")
+        with serving(listing, self.archive) as calls:
+            ggml.install_program(ggml.WHISPER)
+        urls = [call.args[0].full_url for call in calls.call_args_list]
+        self.assertTrue(urls[1].endswith("whisper-blas-bin-x64.zip"))
+
+    def test_a_release_with_nothing_for_windows_says_so(self):
+        with fake_urlopen(json_body(self.release("whisper-bin-ubuntu-x64.tar.gz"))):
+            with self.assertRaises(ggml.LocalError) as caught:
+                ggml.install_program(ggml.WHISPER)
+        self.assertIn("this machine", str(caught.exception))