fix(platform): support Windows storage and native filesystem boundaries

internal/fileutil/filesystem_test.go

@@ -0,0 +1,36 @@
+package fileutil
+
+import (
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestAvailableBytes(t *testing.T) {
+	root := t.TempDir()
+	available, err := AvailableBytes(root)
+	if err != nil || available == 0 {
+		t.Fatalf("available space: %d, %v", available, err)
+	}
+	if _, err := AvailableBytes(filepath.Join(root, "missing")); err == nil {
+		t.Fatal("missing directory accepted")
+	}
+}
+
+func TestLocalPath(t *testing.T) {
+	for _, name := range []string{"notes/中文 note.md", "vault/.rawmark/tree-icons.json"} {
+		if !IsLocalPath(name) {
+			t.Fatalf("valid path rejected: %s", name)
+		}
+	}
+	for _, name := range []string{"", "../outside", "/absolute"} {
+		if IsLocalPath(name) {
+			t.Fatalf("nonlocal path accepted: %s", name)
+		}
+	}
+	for _, name := range []string{"C:note.md", "note.md:stream", "CON", "a/NUL.txt", "a/note. ", "a/note.", "a?/note.md", "a/line\n.md"} {
+		if got := IsLocalPath(name); got != (runtime.GOOS != "windows") {
+			t.Fatalf("native path %q: %v", name, got)
+		}
+	}
+}