diff --git a/internal/helpers/drive_pinned_root_identity_test.go b/internal/helpers/drive_pinned_root_identity_test.go
new file mode 100644
index 00000000..1184f9e8
--- /dev/null
+++ b/internal/helpers/drive_pinned_root_identity_test.go
@@ -0,0 +1,77 @@
+package helpers
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/testseam"
+)
+
+// Windows 会用已打开的目录句柄锁住目录，把「固定后目录被移走／换成软链」这类
+// TOCTOU 在该平台变成物理不可达：os.Rename 直接 ERROR_SHARING_VIOLATION。
+// 但被测的 fail-closed 分支必须在所有平台都覆盖，所以这里提供与真实替换等价的
+// 身份注入：pinnedPullRoot.verify() 与 verifyParent() 都只通过 pullPathStat /
+// pullRootLstat 读取当前身份，让这两个 seam 指向另一个目录即可命中同一分支。
+
+// forcePinnedFallbackForTest 打开后，「移走固定目录」的复现手法一律走身份注入降级。
+// 默认 false：Unix 上用真实移动，验证更强。只有 Windows 才会真的走降级分支，所以
+// 下面的注入回归测试会打开它，让那条路径在任何平台都能被验证。
+var forcePinnedFallbackForTest = false
+
+// swapPinnedRootIdentity 让 absDir 的根身份读数指向另一个目录，使随后的
+// pinnedPullRoot.verify() 判定「本地根目录在同步期间被替换」。
+func swapPinnedRootIdentity(t *testing.T, absDir string) {
+	t.Helper()
+	decoy, err := os.Stat(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := filepath.Clean(absDir)
+	testseam.Swap(t, &pullPathStat, func(path string) (os.FileInfo, error) {
+		if filepath.Clean(path) == want {
+			return decoy, nil
+		}
+		return os.Stat(path)
+	})
+}
+
+// 降级注入只有 Windows 会真的走到（Unix 的 rename 成功）。这里强制打开开关，
+// 确保注入手段本身在任何平台都可回归：不移动目录，但固定根的校验必须随之失败，
+// 且原有目录树不得被动过。
+func TestCrossPlatformCoveragePinnedRootFallbackInjectionFailsVerification(t *testing.T) {
+	testseam.Swap(t, &forcePinnedFallbackForTest, true)
+	dir := t.TempDir()
+	mustWrite(t, filepath.Join(dir, "a.txt"), "pinned-original")
+	root := newPinnedPullRootForCoverage(t, dir)
+	if err := root.verify(); err != nil {
+		t.Fatalf("baseline verify: %v", err)
+	}
+
+	if moved := replacePinnedMirrorRoot(t, dir, filepath.Join(t.TempDir(), "moved")); moved {
+		t.Fatal("降级路径不应真的移动目录")
+	}
+	if err := root.verify(); err == nil || !strings.Contains(err.Error(), "本地根目录在同步期间被替换") {
+		t.Fatalf("身份注入后校验必须失败，got %v", err)
+	}
+	if b, err := os.ReadFile(filepath.Join(dir, "a.txt")); err != nil || string(b) != "pinned-original" {
+		t.Fatalf("降级必须保持原目录树不变: %q err=%v", string(b), err)
+	}
+}
+
+// swapPinnedParentIdentity 让固定根下名为 rel 的父目录身份读数指向另一个目录，
+// 使随后的 verifyParent() 判定「本地目标目录在下载期间被替换」。
+func swapPinnedParentIdentity(t *testing.T, rel string) {
+	t.Helper()
+	decoy, err := os.Lstat(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	testseam.Swap(t, &pullRootLstat, func(parent *os.Root, name string) (os.FileInfo, error) {
+		if filepath.ToSlash(filepath.Clean(name)) == rel {
+			return decoy, nil
+		}
+		return parent.Lstat(name)
+	})
+}
diff --git a/internal/helpers/drive_pull_plan_coverage_test.go b/internal/helpers/drive_pull_plan_coverage_test.go
index 0c155338..f78c6877 100644
--- a/internal/helpers/drive_pull_plan_coverage_test.go
+++ b/internal/helpers/drive_pull_plan_coverage_test.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 	"time"
@@ -350,9 +351,13 @@ func TestCrossPlatformCoverageDrivePullPlanCallers(t *testing.T) {
 			if name == "a.txt" && !moved {
 				moved = true
 				if renameErr := os.Rename(dir, dir+"-pinned"); renameErr != nil {
-					t.Fatal(renameErr)
-				}
-				if mkdirErr := os.Mkdir(dir, 0o755); mkdirErr != nil {
+					// Windows 在固定目录上持有句柄时会锁住它，移走于该平台物理
+					// 不可达；注入等价的根身份变化，命中同一条二次校验分支。
+					if runtime.GOOS != "windows" {
+						t.Fatal(renameErr)
+					}
+					swapPinnedRootIdentity(t, dir)
+				} else if mkdirErr := os.Mkdir(dir, 0o755); mkdirErr != nil {
 					t.Fatal(mkdirErr)
 				}
 			}
diff --git a/internal/helpers/drive_pull_toctou_test.go b/internal/helpers/drive_pull_toctou_test.go
index d32f4a6b..ebb74df1 100644
--- a/internal/helpers/drive_pull_toctou_test.go
+++ b/internal/helpers/drive_pull_toctou_test.go
@@ -8,6 +8,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -30,8 +31,19 @@ func replacePullAncestorWithOutsideLink(t *testing.T, root, outside string) stri
 	t.Helper()
 	sub := filepath.Join(root, "sub")
 	parked := filepath.Join(root, "sub-pinned")
+	if forcePinnedFallbackForTest {
+		swapPinnedParentIdentity(t, "sub")
+		return sub
+	}
 	if err := os.Rename(sub, parked); err != nil {
-		t.Fatal(err)
+		// Windows 在目录内有已打开的句柄（如 pull 的临时文件）时会锁住该目录，
+		// 移走再换链于该平台物理不可达。退化为等价的父目录身份注入，命中
+		// verifyParent 同一条 fail-closed 分支；原目录未移动，故返回 sub。
+		if runtime.GOOS != "windows" {
+			t.Fatal(err)
+		}
+		swapPinnedParentIdentity(t, "sub")
+		return sub
 	}
 	if err := os.Symlink(outside, sub); err != nil {
 		t.Skipf("平台不支持创建符号链接: %v", err)
@@ -39,6 +51,27 @@ func replacePullAncestorWithOutsideLink(t *testing.T, root, outside string) stri
 	return parked
 }
 
+// replacePullCommandRootWithOutsideLink 把命令根整体移走，并在原名处放置指向根外的
+// 符号链接，复现「固定后命令根被换掉」的场景。Windows 在根目录持有已打开句柄时会
+// 锁住该目录，移走于该平台物理不可达，此时退化为等价的根身份注入。
+func replacePullCommandRootWithOutsideLink(t *testing.T, root, parked, outside string) {
+	t.Helper()
+	if forcePinnedFallbackForTest {
+		swapPinnedRootIdentity(t, root)
+		return
+	}
+	if err := os.Rename(root, parked); err != nil {
+		if runtime.GOOS != "windows" {
+			t.Fatal(err)
+		}
+		swapPinnedRootIdentity(t, root)
+		return
+	}
+	if err := os.Symlink(outside, root); err != nil {
+		t.Skipf("symlink unsupported: %v", err)
+	}
+}
+
 func runPullTOCTOUCase(t *testing.T, command string, root string) error {
 	t.Helper()
 	rf := &remoteFile{RelPath: "sub/a.txt", FileID: "F"}
@@ -587,12 +620,7 @@ func TestCrossPlatformCoverageDrivePullCommandPinsRootAcrossAllFiles(t *testing.
 			return err
 		}
 		if calls == 1 {
-			if err := os.Rename(root, parked); err != nil {
-				t.Fatal(err)
-			}
-			if err := os.Symlink(outside, root); err != nil {
-				t.Skipf("symlink unsupported: %v", err)
-			}
+			replacePullCommandRootWithOutsideLink(t, root, parked, outside)
 		}
 		return nil
 	})
@@ -622,12 +650,7 @@ func TestCrossPlatformCoverageDrivePullPlansExistingRootBeforeRemoteRead(t *test
 		if tool != "list_files" {
 			t.Fatalf("root replacement must stop before %s", tool)
 		}
-		if err := os.Rename(root, parked); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.Symlink(outside, root); err != nil {
-			t.Skipf("symlink unsupported: %v", err)
-		}
+		replacePullCommandRootWithOutsideLink(t, root, parked, outside)
 		return `{"result":{"items":[{"name":"a.txt","type":"file","fileId":"A"}]}}`, nil
 	}}
 	getCalls := 0
@@ -727,12 +750,7 @@ func TestCrossPlatformCoverageDriveSyncCommandPinsRootAcrossAllFiles(t *testing.
 			return err
 		}
 		if calls == 1 {
-			if err := os.Rename(root, parked); err != nil {
-				t.Fatal(err)
-			}
-			if err := os.Symlink(outside, root); err != nil {
-				t.Skipf("symlink unsupported: %v", err)
-			}
+			replacePullCommandRootWithOutsideLink(t, root, parked, outside)
 		}
 		return nil
 	})
diff --git a/internal/helpers/drive_push_toctou_test.go b/internal/helpers/drive_push_toctou_test.go
index cfe0ccd3..876333d6 100644
--- a/internal/helpers/drive_push_toctou_test.go
+++ b/internal/helpers/drive_push_toctou_test.go
@@ -5,21 +5,37 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
 	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/testseam"
 )
 
-func replacePinnedMirrorRoot(t *testing.T, root, moved string) {
+// replacePinnedMirrorRoot 返回 true 表示原目录被真实移走、原名处已换成另一个目录；
+// 返回 false 表示走了 Windows 身份注入降级，原目录仍留在原处。依赖「替代目录内容」
+// 的断言必须按返回值分流。
+func replacePinnedMirrorRoot(t *testing.T, root, moved string) bool {
 	t.Helper()
+	if forcePinnedFallbackForTest {
+		swapPinnedRootIdentity(t, root)
+		return false
+	}
 	if err := os.Rename(root, moved); err != nil {
-		t.Fatalf("move pinned root: %v", err)
+		// Windows 在目录内有已打开的句柄（如上传读取中的源文件）时会锁住该目录，
+		// 移走固定根于该平台物理不可达。退化为等价的根身份注入，命中同一条
+		// fail-closed 分支。
+		if runtime.GOOS != "windows" {
+			t.Fatalf("move pinned root: %v", err)
+		}
+		swapPinnedRootIdentity(t, root)
+		return false
 	}
 	if err := os.Mkdir(root, 0o755); err != nil {
 		t.Fatalf("create replacement root: %v", err)
 	}
 	mustWrite(t, filepath.Join(root, "a.txt"), "outside-replacement")
+	return true
 }
 
 // 本地扫描完成后、任何 create_folder/get_upload_info/commit_upload 前若命令行根已
@@ -36,10 +52,11 @@ func TestCrossPlatformCoverageDrivePushSyncRejectRootReplacementBeforeRemoteWrit
 			mustWrite(t, filepath.Join(root, "a.txt"), "pinned-original")
 
 			replaced := false
+			realMove := false
 			caller := &driveScriptCaller{reply: func(tool string, _ map[string]any, _ int) (string, error) {
 				if tool == "list_files" {
 					if !replaced {
-						replacePinnedMirrorRoot(t, root, moved)
+						realMove = replacePinnedMirrorRoot(t, root, moved)
 						replaced = true
 					}
 					return `{"result":{"items":[],"nextToken":""}}`, nil
@@ -68,7 +85,12 @@ func TestCrossPlatformCoverageDrivePushSyncRejectRootReplacementBeforeRemoteWrit
 			if putCalls != 0 {
 				t.Fatalf("OSS PUT must not run after root replacement, got %d", putCalls)
 			}
-			if b, err := os.ReadFile(filepath.Join(root, "a.txt")); err != nil || string(b) != "outside-replacement" {
+			want := "outside-replacement"
+			if !realMove {
+				// 身份注入降级：原目录仍在原处，内容同样不得被镜像流程改写。
+				want = "pinned-original"
+			}
+			if b, err := os.ReadFile(filepath.Join(root, "a.txt")); err != nil || string(b) != want {
 				t.Fatalf("replacement tree changed: %q err=%v", string(b), err)
 			}
 		})
@@ -100,9 +122,10 @@ func TestCrossPlatformCoverageDrivePushSyncUploadReadsPinnedFileHandle(t *testin
 
 			var uploaded string
 			putCalls := 0
+			realMove := false
 			testseam.Swap(t, &pushPutOpenedFile, func(_ context.Context, _ string, _ map[string]string, file *os.File, _ int64) error {
 				putCalls++
-				replacePinnedMirrorRoot(t, root, moved)
+				realMove = replacePinnedMirrorRoot(t, root, moved)
 				body, err := io.ReadAll(file)
 				if err != nil {
 					return err
@@ -125,10 +148,15 @@ func TestCrossPlatformCoverageDrivePushSyncUploadReadsPinnedFileHandle(t *testin
 			if commits := caller.callsFor("commit_upload"); len(commits) != 0 {
 				t.Fatalf("root replacement must prevent commit_upload: %v", commits)
 			}
-			if b, readErr := os.ReadFile(filepath.Join(root, "a.txt")); readErr != nil || string(b) != "outside-replacement" {
-				t.Fatalf("replacement file was read or changed: %q err=%v", string(b), readErr)
-			}
-			if b, readErr := os.ReadFile(filepath.Join(moved, "a.txt")); readErr != nil || string(b) != "pinned-original" {
+			if realMove {
+				if b, readErr := os.ReadFile(filepath.Join(root, "a.txt")); readErr != nil || string(b) != "outside-replacement" {
+					t.Fatalf("replacement file was read or changed: %q err=%v", string(b), readErr)
+				}
+				if b, readErr := os.ReadFile(filepath.Join(moved, "a.txt")); readErr != nil || string(b) != "pinned-original" {
+					t.Fatalf("pinned original changed: %q err=%v", string(b), readErr)
+				}
+			} else if b, readErr := os.ReadFile(filepath.Join(root, "a.txt")); readErr != nil || string(b) != "pinned-original" {
+				// 身份注入降级：原目录仍在原处，内容同样不得被上传路径改写。
 				t.Fatalf("pinned original changed: %q err=%v", string(b), readErr)
 			}
 		})