diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9f7a4fa6a7..8924b6f858 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -318,6 +318,32 @@ jobs:
               "TestHeldPathsCoverOnlyTheSameFileAcrossCaseSpellings",
               "TestLegacyWaitDoesNotConsumeExecutionCapacity"] - $tests | length) == 0
           ' "$RUNNER_TEMP/isolation-owners.jsonl"
+          jq -se '
+            . as $events |
+            {"reasonix/internal/platform/worktree": [
+               "TestApplyPathsRejectsRedirectedAncestors",
+               "TestApplyPathsRejectsRedirectedAncestors/outside_delete",
+               "TestApplyPathsRejectsRedirectedAncestors/inside_delete",
+               "TestApplyPathsRejectsRedirectedAncestors/dangling_delete",
+               "TestApplyPathsRejectsRedirectedAncestors/outside_write",
+               "TestApplyPathsRejectsRedirectedAncestors/inside_write",
+               "TestApplyPathsRejectsRedirectedAncestors/regular_parent",
+               "TestApplyPathsRejectsRedirectedAncestors/unchanged",
+               "TestApplyPathsRejectsRedirectedAncestors/missing_creation",
+               "TestWriteChangesRejectsRedirectedDeletion",
+               "TestWriteChangesUnlinksLeafDirectoryLink",
+               "TestWholeWorkspaceApplyPreservesFileToDirectoryTransition"],
+             "reasonix/internal/runtime/isolation": [
+               "TestApplyToolRetainsResultAfterAncestorReplacement"]} |
+            to_entries | all(.[]; . as $package |
+              ([ $events[] | select(.Package == $package.key and .Test == null and
+                 (.Action == "pass" or .Action == "fail" or .Action == "skip")) ] |
+               length == 1 and .[0].Action == "pass") and
+              all(.value[]; . as $test |
+                [ $events[] | select(.Package == $package.key and .Test == $test and
+                  (.Action == "pass" or .Action == "fail" or .Action == "skip")) ] |
+                length == 1 and .[0].Action == "pass"))
+          ' "$RUNNER_TEMP/isolation-owners.jsonl"
 
       - name: upload Windows isolation test inventory
         if: always() && env.RUN_STEPS == 'true' && runner.os == 'Windows' && github.event_name == 'pull_request'
diff --git a/docs/WORKTREE_APPLY_ANCESTORS.md b/docs/WORKTREE_APPLY_ANCESTORS.md
new file mode 100644
index 0000000000..fcb4ffd0d7
--- /dev/null
+++ b/docs/WORKTREE_APPLY_ANCESTORS.md
@@ -0,0 +1,95 @@
+---
+owner: @SivanCola
+backup: @esengine
+status: active
+reviewed: 2026-10-28
+---
+
+# Worktree apply ancestors / 工作树应用的父目录边界
+
+## Behavior / 行为
+
+An isolated candidate names Git directory entries. If a source ancestor becomes
+a directory link while that candidate runs, matching leaf bytes do not establish
+that the candidate still addresses the original path.
+
+Applying now refuses that
+ancestor with the existing path-conflict result before reading leaf content or
+writing a sibling change. Links inside the repository are refused too, including
+links from a selected project folder to its surrounding repository.
+
+隔离候选使用 Git 目录项路径。候选运行期间，如果源文件的父目录被换成目录链接，
+即使最终文件内容相同，也不能认定仍是原路径。应用现在会在读取最终文件内容或写入
+其他变更前，以已有的路径冲突结果拒绝该父目录。仓库内部链接也会被拒绝，包括从所选
+项目目录指向仓库其他目录的链接。
+
+Deletion ancestors are checked in the shared worktree publisher, including
+ordinary isolation and best-of callers. Path-by-path apply checks every changed
+path's ancestors before hashing leaves.
+
+Deletion uses an open `os.Root` for the source repository, so a parent
+link cannot redirect that filesystem operation outside the opened root. A link
+at the final deleted entry is removed as an entry; its target is not removed.
+
+Whole-workspace application may delete a file before creating a directory at
+the same name. Its deletion preflight preserves that conversion; Git owns the
+subsequent restoration. Path-by-path application's existing refusal of
+unsupported tree entries is unchanged.
+
+共同 worktree 发布层检查删除路径的父目录，覆盖普通隔离和 best-of 调用方。逐路径应用
+还在计算文件摘要前检查所有变更路径的父目录。
+
+删除通过源仓库的已打开 `os.Root` 执行，父目录链接不能将该删除
+操作重定向到根目录外。被删除的最终目录项本身若是链接，只删除链接，不删除其目标。
+
+整工作区应用可能先删除一个文件，再创建同名目录。删除前置检查保留这一转换，后续
+恢复由 Git 负责。逐路径应用原有的“不支持的 tree 条目”拒绝规则不变。
+
+The existing apply tool reports the conflict and retains the original result ID
+and candidate. After restoring the directory, reopening the Store can apply that
+same ID. New directories, ordinary deletions, and unrelated workspace edits keep
+their existing behavior.
+
+No configuration, tool schema, prompt prefix, journal,
+or persisted format changes; existing results use the checks when applied by the
+new reader. Older binaries retain their previous behavior.
+
+已有应用工具报告冲突并保留原 result ID 和候选。恢复目录后，重新打开 Store 可使用
+同一 ID 应用。新建目录、正常删除及工作区其他修改保留原行为。不修改配置、工具
+schema、提示词前缀、journal 或持久化格式；新版本应用旧结果时同样执行检查。
+旧二进制仍保留原行为。
+
+## Evidence and limits / 证据与限制
+
+Regression fixtures create real Git candidates, then replace source ancestors
+with external, internal, dangling, or non-directory entries. They check both
+deletions and writes, sibling preservation, and Store reconstruction followed by
+same-ID retry.
+
+Windows fixtures use directory junctions; Unix fixtures use
+symbolic links. The existing Windows isolation inventory requires every named
+regression to pass, with no missing, duplicate, failed, or skipped terminal.
+
+回归测试创建真实 Git 候选，再将源父目录换成外部链接、内部链接、悬空链接或普通文件，
+覆盖删除、写入、其他文件保持不变，以及重建 Store 后用原 ID 重试。Windows 使用目录
+junction，Unix 使用符号链接。已有 Windows 隔离清单要求每个指定测试通过，拒绝缺失、
+重复、失败或跳过的终态。
+
+These are ancestor-type preconditions and confined deletion, not an atomic
+multi-file transaction or an inode compare-and-swap. A directory replaced by
+another real directory containing identical files is not distinguished.
+
+Checks cannot fence arbitrary writers between inspection and Git restoration. File
+restoration still uses Git, and errors after publication begins may leave partial
+changes.
+
+Physical process settlement, remote effects, mount changes, complete
+native publisher ownership, and crash-safe rollback remain separate work.
+
+本修补提供父目录类型前置条件及受根目录约束的删除，不是多文件原子事务或 inode CAS。
+真实目录被换成包含相同文件的另一真实目录时，不会区分。
+
+检查无法阻止任意外部写入者
+在检查与 Git 恢复之间修改路径。文件恢复仍由 Git 执行，开始发布后的错误可能留下部分
+变更。进程物理终结、远程效果、挂载点变化、完整原生发布所有权与崩溃安全回滚仍是
+独立的未完成工作。
diff --git a/internal/platform/worktree/apply_ancestor_test.go b/internal/platform/worktree/apply_ancestor_test.go
new file mode 100644
index 0000000000..60f8e53441
--- /dev/null
+++ b/internal/platform/worktree/apply_ancestor_test.go
@@ -0,0 +1,162 @@
+package worktree
+
+import (
+	"context"
+	"errors"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+
+	"reasonix/internal/base/testenv"
+)
+
+func TestApplyPathsRejectsRedirectedAncestors(t *testing.T) {
+	for _, kind := range []string{"outside_delete", "inside_delete", "dangling_delete", "outside_write", "inside_write", "regular_parent", "unchanged", "missing_creation"} {
+		t.Run(kind, func(t *testing.T) {
+			repo := initRepo(t)
+			writeRepoFile(t, repo, "app/nested/victim.txt", "original\n")
+			writeRepoFile(t, repo, "app/first.txt", "sibling\n")
+			gitIn(t, repo, "add", "-A")
+			gitIn(t, repo, "commit", "-q", "-m", "add project")
+			snap, err := TakeSnapshot(t.Context(), opened(t, filepath.Join(repo, "app")))
+			if err != nil {
+				t.Fatal(err)
+			}
+			c, err := CreateCandidate(t.Context(), snap, filepath.Join(testenv.TempDir(t), "candidates"))
+			if err != nil {
+				t.Fatal(err)
+			}
+			t.Cleanup(func() { _ = RemoveCandidate(context.Background(), snap, c) })
+			if err := os.Remove(filepath.Join(c.WorkspaceRoot, "first.txt")); err != nil {
+				t.Fatal(err)
+			}
+			writeTarget := kind == "outside_write" || kind == "inside_write"
+			if writeTarget {
+				writeRepoFile(t, c.WorkspaceRoot, "nested/victim.txt", "candidate\n")
+			} else if err := os.Remove(filepath.Join(c.WorkspaceRoot, "nested/victim.txt")); err != nil {
+				t.Fatal(err)
+			}
+			if kind == "missing_creation" {
+				writeRepoFile(t, c.WorkspaceRoot, "new/deep/created.txt", "created\n")
+			}
+			tree, changes, err := CandidateTree(t.Context(), snap, c)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(changes) < 2 {
+				t.Fatalf("missing candidate changes: %+v", changes)
+			}
+			outside := testenv.TempDir(t)
+			if kind == "inside_delete" || kind == "inside_write" {
+				outside = filepath.Join(repo, "elsewhere")
+			}
+			writeRepoFile(t, outside, "victim.txt", "original\n")
+			parent := filepath.Join(repo, "app", "nested")
+			control := kind == "unchanged" || kind == "missing_creation"
+			if !control {
+				if err := os.Rename(parent, filepath.Join(repo, "saved")); err != nil {
+					t.Fatal(err)
+				}
+				if kind == "regular_parent" {
+					if err := os.WriteFile(parent, []byte("not a directory\n"), 0o644); err != nil {
+						t.Fatal(err)
+					}
+				} else {
+					target := outside
+					if kind == "dangling_delete" {
+						target = filepath.Join(outside, "missing")
+					}
+					linkApplyDirectory(t, target, parent)
+				}
+			}
+			err = ApplyPaths(t.Context(), snap, tree, changes)
+			if got := readRepoFile(t, outside, "victim.txt"); got != "original\n" {
+				t.Fatalf("outside content changed: %q", got)
+			}
+			if control {
+				if err != nil {
+					t.Fatal(err)
+				}
+				for _, path := range []string{"app/first.txt", "app/nested/victim.txt"} {
+					if _, err := os.Lstat(filepath.Join(repo, path)); !os.IsNotExist(err) {
+						t.Fatalf("deletion %s: %v", path, err)
+					}
+				}
+				if kind == "missing_creation" && readRepoFile(t, repo, "app/new/deep/created.txt") != "created\n" {
+					t.Fatal("missing parent creation failed")
+				}
+				return
+			}
+			var conflict *ConflictError
+			if !errors.As(err, &conflict) || len(conflict.Paths) != 1 || conflict.Paths[0] != "app/nested/victim.txt" {
+				t.Fatalf("ancestor conflict = %v", err)
+			}
+			if got := readRepoFile(t, repo, "app/first.txt"); got != "sibling\n" {
+				t.Fatalf("refusal wrote sibling: %q", got)
+			}
+		})
+	}
+}
+
+func TestWriteChangesRejectsRedirectedDeletion(t *testing.T) {
+	repo := initRepo(t)
+	outside := testenv.TempDir(t)
+	writeRepoFile(t, outside, "victim.txt", "original\n")
+	linkApplyDirectory(t, outside, filepath.Join(repo, "nested"))
+	err := writeChanges(t.Context(), opened(t, repo), "HEAD", []Change{{Status: "D", Path: "nested/victim.txt"}})
+	if err == nil {
+		t.Fatal("publication accepted a redirected deletion")
+	}
+	if got := readRepoFile(t, outside, "victim.txt"); got != "original\n" {
+		t.Fatalf("outside file changed: %q", got)
+	}
+}
+
+func TestWriteChangesUnlinksLeafDirectoryLink(t *testing.T) {
+	repo := initRepo(t)
+	outside := testenv.TempDir(t)
+	writeRepoFile(t, outside, "victim.txt", "original\n")
+	link := filepath.Join(repo, "link")
+	linkApplyDirectory(t, outside, link)
+	if err := writeChanges(t.Context(), opened(t, repo), "HEAD", []Change{{Status: "D", Path: "link"}}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Lstat(link); !os.IsNotExist(err) {
+		t.Fatalf("leaf link was not removed: %v", err)
+	}
+	if got := readRepoFile(t, outside, "victim.txt"); got != "original\n" {
+		t.Fatalf("leaf deletion followed the link: %q", got)
+	}
+}
+
+func TestWholeWorkspaceApplyPreservesFileToDirectoryTransition(t *testing.T) {
+	repo, snap, c, finish := isolatedCandidate(t)
+	if err := os.Remove(filepath.Join(c.WorkspaceRoot, "a.txt")); err != nil {
+		t.Fatal(err)
+	}
+	writeRepoFile(t, c.WorkspaceRoot, "a.txt/child.txt", "converted\n")
+	tree, changes := finish()
+	if err := Apply(t.Context(), snap, tree, changes); err != nil {
+		t.Fatal(err)
+	}
+	if got := readRepoFile(t, repo, "a.txt/child.txt"); got != "converted\n" {
+		t.Fatalf("conversion = %q", got)
+	}
+	if got := readRepoFile(t, repo, "b.txt"); got != "two\n" {
+		t.Fatalf("sibling = %q", got)
+	}
+}
+
+func linkApplyDirectory(t *testing.T, target, path string) {
+	t.Helper()
+	if runtime.GOOS == "windows" {
+		out, err := exec.Command("cmd", "/c", "mklink", "/J", path, target).CombinedOutput()
+		if err != nil {
+			t.Fatalf("create directory junction: %v %s", err, out)
+		}
+	} else if err := os.Symlink(target, path); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/internal/platform/worktree/apply_ancestors.go b/internal/platform/worktree/apply_ancestors.go
new file mode 100644
index 0000000000..21be3ac790
--- /dev/null
+++ b/internal/platform/worktree/apply_ancestors.go
@@ -0,0 +1,50 @@
+package worktree
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"slices"
+)
+
+// Git trees name directory entries, not paths reached through directory links.
+// Check every ancestor before hashing leaves or publishing any sibling change.
+func checkApplyAncestors(root *os.Root, changes []Change) error {
+	checked := make(map[string]bool)
+	var conflicts []string
+	for _, ch := range changes {
+		if !filepath.IsLocal(filepath.FromSlash(ch.Path)) {
+			return fmt.Errorf("%w: %s", ErrOutsideWorkspace, ch.Path)
+		}
+		var parents []string
+		for p := filepath.Dir(filepath.FromSlash(ch.Path)); p != "."; p = filepath.Dir(p) {
+			if p == filepath.Dir(p) {
+				return fmt.Errorf("%w: %s", ErrOutsideWorkspace, ch.Path)
+			}
+			parents = append(parents, p)
+		}
+		slices.Reverse(parents)
+		for _, parent := range parents {
+			blocked, known := checked[parent]
+			if !known {
+				info, err := root.Lstat(parent)
+				if os.IsNotExist(err) {
+					break
+				}
+				if err != nil {
+					return fmt.Errorf("inspect apply ancestor %s: %w", parent, err)
+				}
+				blocked = !info.IsDir()
+				checked[parent] = blocked
+			}
+			if blocked {
+				conflicts = append(conflicts, ch.Path)
+				break
+			}
+		}
+	}
+	if len(conflicts) > 0 {
+		return &ConflictError{Paths: conflicts}
+	}
+	return nil
+}
diff --git a/internal/platform/worktree/apply_paths.go b/internal/platform/worktree/apply_paths.go
index b2cf332853..dbcf004ebb 100644
--- a/internal/platform/worktree/apply_paths.go
+++ b/internal/platform/worktree/apply_paths.go
@@ -83,6 +83,14 @@ func ApplyPaths(ctx context.Context, snap Snapshot, tree string, changes []Chang
 	if err != nil {
 		return err
 	}
+	root, err := os.OpenRoot(source.WorkTree)
+	if err != nil {
+		return err
+	}
+	defer root.Close()
+	if err := checkApplyAncestors(root, changes); err != nil {
+		return err
+	}
 	live, err := liveBlobs(ctx, source, paths, trust)
 	if err != nil {
 		return err
@@ -104,7 +112,7 @@ func ApplyPaths(ctx context.Context, snap Snapshot, tree string, changes []Chang
 	if len(conflicts) > 0 {
 		return &ConflictError{Paths: conflicts}
 	}
-	return writeChanges(ctx, source, tree, pending)
+	return writeChangesInRoot(ctx, source, root, tree, pending)
 }
 
 // ChangePaths is where each change lands in the source workspace, refusing any
@@ -267,16 +275,33 @@ func hashText(ctx context.Context, repo gitcmd.Repo, text string) (string, error
 
 // writeChanges writes tree's version of each change into repo's files.
 func writeChanges(ctx context.Context, repo gitcmd.Repo, tree string, changes []Change) error {
-	repoRoot := repo.WorkTree
+	root, err := os.OpenRoot(repo.WorkTree)
+	if err != nil {
+		return err
+	}
+	defer root.Close()
+	return writeChangesInRoot(ctx, repo, root, tree, changes)
+}
+
+func writeChangesInRoot(ctx context.Context, repo gitcmd.Repo, root *os.Root, tree string, changes []Change) error {
+	var deletions []Change
 	var restore []string
 	for _, ch := range changes {
 		if ch.Status == "D" {
-			if err := os.Remove(filepath.Join(repoRoot, filepath.FromSlash(ch.Path))); err != nil && !os.IsNotExist(err) {
-				return fmt.Errorf("apply deletion of %s: %w", ch.Path, err)
-			}
-			continue
+			deletions = append(deletions, ch)
+		} else {
+			restore = append(restore, ch.Path)
+		}
+	}
+	// Restored paths may need directories created by these deletions. Git owns
+	// their checkout; deletion must not follow a redirected source ancestor.
+	if err := checkApplyAncestors(root, deletions); err != nil {
+		return err
+	}
+	for _, ch := range deletions {
+		if err := root.Remove(filepath.FromSlash(ch.Path)); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("apply deletion of %s: %w", ch.Path, err)
 		}
-		restore = append(restore, ch.Path)
 	}
 	if len(restore) == 0 {
 		return nil
diff --git a/internal/runtime/isolation/apply_ancestor_test.go b/internal/runtime/isolation/apply_ancestor_test.go
new file mode 100644
index 0000000000..4c7b7c4785
--- /dev/null
+++ b/internal/runtime/isolation/apply_ancestor_test.go
@@ -0,0 +1,84 @@
+package isolation
+
+import (
+	"context"
+	"errors"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"slices"
+	"testing"
+
+	"reasonix/internal/base/testenv"
+	"reasonix/internal/contract/tool"
+)
+
+func TestApplyToolRetainsResultAfterAncestorReplacement(t *testing.T) {
+	repo := gitRepo(t)
+	write(t, repo, "nested/victim.txt", "original\n")
+	managed := testenv.TempDir(t)
+	s := NewStore(managed, repo, opened(t, repo))
+	report, err := s.Execute(t.Context(), func(_ context.Context, run Run) (Outcome, error) {
+		write(t, run.WorkspaceRoot, "a.txt", "candidate\n")
+		return Outcome{}, os.Remove(filepath.Join(run.WorkspaceRoot, "nested/victim.txt"))
+	}, repo, "delete a nested file", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	id := idOf(t, report)
+	e, err := s.lookup(id)
+	if err != nil {
+		t.Fatal(err)
+	}
+	outside := testenv.TempDir(t)
+	write(t, outside, "victim.txt", "original\n")
+	parent, saved := filepath.Join(repo, "nested"), filepath.Join(repo, "saved")
+	if err := os.Rename(parent, saved); err != nil {
+		t.Fatal(err)
+	}
+	if runtime.GOOS == "windows" {
+		out, err := exec.Command("cmd", "/c", "mklink", "/J", parent, outside).CombinedOutput()
+		if err != nil {
+			t.Fatalf("create directory junction: %v %s", err, out)
+		}
+	} else if err := os.Symlink(outside, parent); err != nil {
+		t.Fatal(err)
+	}
+	resumed := NewStore(managed, repo, opened(t, repo))
+	_, err = NewApplyTool(resumed).Execute(t.Context(), args(id))
+	if got := read(t, outside, "victim.txt"); got != "original\n" {
+		t.Fatalf("external file changed: %q", got)
+	}
+	var refusal tool.Refusal
+	if !errors.As(err, &refusal) || refusal.Code != CodeApplyConflict {
+		t.Fatalf("apply did not report the ancestor conflict: %v", err)
+	}
+	if !slices.Contains(resumed.Pending(), id) {
+		t.Fatal("result lost its original pending ID")
+	}
+	if _, err := os.Stat(e.Cand.WorktreeRoot); err != nil {
+		t.Fatalf("candidate lost after refusal: %v", err)
+	}
+	if got := read(t, repo, "a.txt"); got != "one\n" {
+		t.Fatalf("refusal wrote sibling: %q", got)
+	}
+	if err := os.Remove(parent); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Rename(saved, parent); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := NewApplyTool(NewStore(managed, repo, opened(t, repo))).Execute(t.Context(), args(id)); err != nil {
+		t.Fatalf("same-ID retry: %v", err)
+	}
+	if read(t, repo, "a.txt") != "candidate\n" {
+		t.Fatal("retry did not apply sibling")
+	}
+	if _, err := os.Stat(filepath.Join(repo, "nested/victim.txt")); !os.IsNotExist(err) {
+		t.Fatalf("retry did not delete intended path: %v", err)
+	}
+	if got := read(t, outside, "victim.txt"); got != "original\n" {
+		t.Fatalf("retry changed external file: %q", got)
+	}
+}
diff --git a/release-notes/studio/unreleased/14025-worktree-apply-ancestors.md b/release-notes/studio/unreleased/14025-worktree-apply-ancestors.md
new file mode 100644
index 0000000000..e3ab051d05
--- /dev/null
+++ b/release-notes/studio/unreleased/14025-worktree-apply-ancestors.md
@@ -0,0 +1,11 @@
+## 修复
+
+- 应用隔离结果时，拒绝被换成目录链接或普通文件的父目录，避免重定向删除；保留原结果 ID，恢复目录后可重试。 (#14025)
+- 保留正常删除、新目录创建、最终链接删除和整工作区文件转目录行为。 (#14025)
+
+<!-- lang:en -->
+
+## Fixed
+
+- Refuse changed directory-link or file ancestors during isolated application; prevent redirected deletion and retain the original result ID for retry after restoring the directory. (#14025)
+- Preserve ordinary deletion, new-directory creation, leaf-link deletion, and whole-workspace file-to-directory conversion. (#14025)