fix: open native directory picker for new instances

internal/platform/files/directory_picker.go

@@ -0,0 +1,9 @@
+package files
+
+import "context"
+
+// DirectoryPicker opens a platform directory chooser. The implementation must
+// block only in its own goroutine; UI callers receive the result asynchronously.
+type DirectoryPicker interface {
+	ChooseDirectory(context.Context) (string, error)
+}

internal/platform/files/directory_picker_other.go

@@ -0,0 +1,18 @@
+//go:build !windows
+
+package files
+
+import (
+	"context"
+	"errors"
+)
+
+var ErrSelectionCanceled = context.Canceled
+
+type unsupportedDirectoryPicker struct{}
+
+func NewDirectoryPicker() DirectoryPicker { return unsupportedDirectoryPicker{} }
+
+func (unsupportedDirectoryPicker) ChooseDirectory(context.Context) (string, error) {
+	return "", errors.New("directory picker is only supported on Windows")
+}

internal/platform/files/directory_picker_windows.go

@@ -0,0 +1,62 @@
+//go:build windows
+
+package files
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+var ErrSelectionCanceled = context.Canceled
+
+type commandRunner interface {
+	Run(context.Context, string, ...string) ([]byte, error)
+}
+
+type execRunner struct{}
+
+func (execRunner) Run(ctx context.Context, name string, args ...string) ([]byte, error) {
+	return exec.CommandContext(ctx, name, args...).Output()
+}
+
+type windowsDirectoryPicker struct{ runner commandRunner }
+
+func NewDirectoryPicker() DirectoryPicker { return windowsDirectoryPicker{runner: execRunner{}} }
+
+func newDirectoryPickerWithRunner(runner commandRunner) windowsDirectoryPicker {
+	return windowsDirectoryPicker{runner: runner}
+}
+
+func (p windowsDirectoryPicker) ChooseDirectory(ctx context.Context) (string, error) {
+	if err := ctx.Err(); err != nil {
+		return "", err
+	}
+	output, err := p.runner.Run(ctx, "powershell.exe",
+		"-NoProfile", "-NonInteractive", "-STA", "-WindowStyle", "Hidden", "-Command", folderDialogScript)
+	if err != nil {
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return "", ctxErr
+		}
+		return "", fmt.Errorf("open directory picker: %w", err)
+	}
+	selected := strings.TrimSpace(string(output))
+	if selected == "" {
+		return "", ErrSelectionCanceled
+	}
+	if !filepath.IsAbs(selected) {
+		return "", fmt.Errorf("directory picker returned a non-absolute path")
+	}
+	return filepath.Clean(selected), nil
+}
+
+const folderDialogScript = `[Console]::OutputEncoding = [System.Text.UTF8Encoding]::new($false)
+Add-Type -AssemblyName System.Windows.Forms
+$dialog = New-Object System.Windows.Forms.FolderBrowserDialog
+$dialog.Description = '选择浏览器 User Data Dir'
+$dialog.ShowNewFolderButton = $true
+if ($dialog.ShowDialog() -eq [System.Windows.Forms.DialogResult]::OK) {
+  [Console]::Out.Write($dialog.SelectedPath)
+}`

internal/platform/files/directory_picker_windows_test.go

@@ -0,0 +1,45 @@
+//go:build windows
+
+package files
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+)
+
+type fakeRunner struct {
+	name string
+	args []string
+	out  []byte
+	err  error
+}
+
+func (f *fakeRunner) Run(_ context.Context, name string, args ...string) ([]byte, error) {
+	f.name = name
+	f.args = append([]string(nil), args...)
+	return f.out, f.err
+}
+
+func TestWindowsDirectoryPickerReturnsCleanAbsolutePath(t *testing.T) {
+	runner := &fakeRunner{out: []byte("C:\\profiles\\demo\\\r\n")}
+	picker := newDirectoryPickerWithRunner(runner)
+	got, err := picker.ChooseDirectory(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != `C:\profiles\demo` {
+		t.Fatalf("path = %q", got)
+	}
+	if runner.name != "powershell.exe" || !strings.Contains(strings.Join(runner.args, " "), "-STA") {
+		t.Fatalf("unexpected picker command: %s %v", runner.name, runner.args)
+	}
+}
+
+func TestWindowsDirectoryPickerTreatsEmptySelectionAsCanceled(t *testing.T) {
+	picker := newDirectoryPickerWithRunner(&fakeRunner{})
+	if _, err := picker.ChooseDirectory(context.Background()); !errors.Is(err, ErrSelectionCanceled) {
+		t.Fatalf("error = %v", err)
+	}
+}