fix(update): preserve user data dirs during Git-based update via git clean -e excludes

git clean -fd in _perform_git_update deleted untracked, non-ignored
directories (wildcards, stats, backups, civitai, caches, logs) during
portable-mode updates, since released tags do not list them in .gitignore.
Add -e excludes for all user-managed paths to both nightly and stable
update branches. Add regression tests for both paths.

tests/routes/test_update_routes.py

@@ -59,3 +59,180 @@ async def test_get_nightly_version_network_error_logs_warning(monkeypatch, caplo
     assert changelog == []
     assert "Unable to reach GitHub for nightly version" in caplog.text
     assert "Traceback" not in caplog.text
+
+
+def test_clean_excludes_covers_user_data_dirs():
+    """git clean must receive -e excludes for every user-managed dir."""
+    excludes = update_routes._clean_excludes()
+    assert "-e" in excludes  # at least one exclude flag present
+    for name in update_routes._PRESERVE_DIRS:
+        assert name in excludes
+        assert f"{name}/**" in excludes
+
+
+@pytest.mark.asyncio
+async def test_perform_git_update_preserves_user_dirs(monkeypatch, tmp_path):
+    """``git clean`` must be called with -e excludes for user data dirs.
+
+    Regression test for portable-mode updates wiping wildcards/, stats/,
+    backups/, etc. because ``git clean -fd`` removed untracked, non-ignored
+    directories.
+    """
+    calls = []
+
+    class FakeGit:
+        def reset(self, *args, **kwargs):
+            calls.append(("reset", args))
+
+        def clean(self, *args, **kwargs):
+            calls.append(("clean", args))
+
+        def checkout(self, *args, **kwargs):
+            calls.append(("checkout", args))
+
+    class FakeRemote:
+        def fetch(self):
+            calls.append(("fetch", ()))
+
+        def pull(self, *args, **kwargs):
+            calls.append(("pull", args))
+
+    class FakeRemotes:
+        origin = FakeRemote()
+
+    class FakeCommit:
+        hexsha = "abcdef123456"
+
+    class FakeHeads:
+        def __getitem__(self, name):
+            class Head:
+                def checkout(self_inner):
+                    calls.append(("head-checkout", (name,)))
+            return Head()
+
+    class FakeBranches:
+        names = ["main"]
+
+        def __iter__(self):
+            class B:
+                name = "main"
+            return iter([B()])
+
+    class FakeRepo:
+        def __init__(self, path):
+            calls.append(("repo", (path,)))
+
+        git = FakeGit()
+        remotes = FakeRemotes()
+        head = type("H", (), {"commit": FakeCommit()})()
+        branches = FakeBranches()
+        heads = FakeHeads()
+
+        def create_head(self, name, ref):
+            calls.append(("create_head", (name, ref)))
+
+    class FakeGitModule:
+        class Repo:
+            def __new__(cls, path):
+                return FakeRepo(path)
+
+        class exc:
+            class GitError(Exception):
+                pass
+
+    import builtins
+
+    real_import = builtins.__import__
+
+    def fake_import(name, *args, **kwargs):
+        if name == "git":
+            return FakeGitModule
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    success, version = await update_routes.UpdateRoutes._perform_git_update(
+        str(tmp_path), nightly=True
+    )
+
+    assert success is True
+    clean_calls = [c for c in calls if c[0] == "clean"]
+    assert len(clean_calls) == 1
+    clean_args = clean_calls[0][1]
+    # Every preserved dir must be excluded via -e
+    for name in update_routes._PRESERVE_DIRS:
+        assert name in clean_args, f"{name} missing from git clean excludes"
+        assert f"{name}/**" in clean_args, f"{name}/** missing from git clean excludes"
+        # Ensure there's an -e before each name occurrence
+        idx = clean_args.index(name)
+        assert clean_args[idx - 1] == "-e"
+
+
+@pytest.mark.asyncio
+async def test_perform_git_update_stable_preserves_user_dirs(monkeypatch, tmp_path):
+    """Stable (tag) update path must also pass -e excludes to git clean."""
+    calls = []
+
+    class FakeGit:
+        def reset(self, *args, **kwargs):
+            calls.append(("reset", args))
+
+        def clean(self, *args, **kwargs):
+            calls.append(("clean", args))
+
+        def checkout(self, *args, **kwargs):
+            calls.append(("checkout", args))
+
+    class FakeRemote:
+        def fetch(self):
+            calls.append(("fetch", ()))
+
+    class FakeRemotes:
+        origin = FakeRemote()
+
+    class FakeCommit:
+        committed_datetime = "2026-01-01"
+
+    class FakeTag:
+        name = "v9.9.9"
+        commit = FakeCommit()
+
+    class FakeRepo:
+        def __init__(self, path):
+            calls.append(("repo", (path,)))
+
+        git = FakeGit()
+        remotes = FakeRemotes()
+        tags = [FakeTag()]
+
+    class FakeGitModule:
+        class Repo:
+            def __new__(cls, path):
+                return FakeRepo(path)
+
+        class exc:
+            class GitError(Exception):
+                pass
+
+    import builtins
+
+    real_import = builtins.__import__
+
+    def fake_import(name, *args, **kwargs):
+        if name == "git":
+            return FakeGitModule
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    success, version = await update_routes.UpdateRoutes._perform_git_update(
+        str(tmp_path), nightly=False
+    )
+
+    assert success is True
+    assert version == "v9.9.9"
+    clean_calls = [c for c in calls if c[0] == "clean"]
+    assert len(clean_calls) == 1
+    clean_args = clean_calls[0][1]
+    for name in update_routes._PRESERVE_DIRS:
+        assert name in clean_args, f"{name} missing from git clean excludes (stable)"