diff --git a/codex-rs/tui/src/app/input.rs b/codex-rs/tui/src/app/input.rs
index e386834d3c..526905ac1f 100644
--- a/codex-rs/tui/src/app/input.rs
+++ b/codex-rs/tui/src/app/input.rs
@@ -107,8 +107,19 @@ impl App {
         };
 
         let seed = self.chat_widget.composer_text_with_pending();
+        let config = self.chat_widget.config_ref();
+        let file_system_policy = config.permissions.file_system_sandbox_policy();
         let editor_result = tui
-            .with_restored(|| async { external_editor::run_editor(&seed, &editor_cmd).await })
+            .with_restored(|| async {
+                external_editor::run_editor(
+                    &seed,
+                    &editor_cmd,
+                    config.codex_home.as_path(),
+                    &file_system_policy,
+                    config.cwd.as_path(),
+                )
+                .await
+            })
             .await;
         self.reset_external_editor_state(tui);
 
diff --git a/codex-rs/tui/src/app/tests.rs b/codex-rs/tui/src/app/tests.rs
index 95fbd2f4b1..04322ea582 100644
--- a/codex-rs/tui/src/app/tests.rs
+++ b/codex-rs/tui/src/app/tests.rs
@@ -318,6 +318,53 @@ async fn cyber_model_auto_review_notice_snapshot() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+#[serial_test::serial]
+async fn external_editor_writable_directory_rejected_snapshot() -> Result<()> {
+    struct RestoreVisual(Option<std::ffi::OsString>);
+
+    impl Drop for RestoreVisual {
+        fn drop(&mut self) {
+            match self.0.take() {
+                Some(value) => unsafe { std::env::set_var("VISUAL", value) },
+                None => unsafe { std::env::remove_var("VISUAL") },
+            }
+        }
+    }
+
+    let (mut app, mut app_event_rx, _op_rx) = make_test_app_with_channels().await;
+    let codex_home = app.chat_widget.config_ref().codex_home.clone();
+    let fallback_home = dirs::home_dir()
+        .expect("home directory")
+        .join(".codex")
+        .abs();
+    let workspace_codex_home = app.chat_widget.config_ref().cwd.join(".codex");
+    let permission_profile = PermissionProfile::workspace_write_with(
+        &[codex_home, fallback_home, workspace_codex_home],
+        codex_protocol::permissions::NetworkSandboxPolicy::Restricted,
+        /*exclude_tmpdir_env_var*/ true,
+        /*exclude_slash_tmp*/ true,
+    );
+    app.chat_widget
+        .set_permission_profile_from_session_snapshot(PermissionProfileSnapshot::legacy(
+            permission_profile,
+        ))?;
+    let mut tui = crate::tui::test_support::make_test_tui()?;
+    let restore_visual = RestoreVisual(std::env::var_os("VISUAL"));
+    unsafe { std::env::set_var("VISUAL", "editor") };
+
+    app.launch_external_editor(&mut tui).await;
+    drop(restore_visual);
+
+    let cell = match app_event_rx.try_recv() {
+        Ok(AppEvent::InsertHistoryCell(cell)) => cell,
+        other => panic!("expected InsertHistoryCell event, got {other:?}"),
+    };
+    let rendered = lines_to_single_string(&cell.display_lines(/*width*/ 80));
+    assert_app_snapshot!("external_editor_writable_directory_rejected", rendered);
+    Ok(())
+}
+
 #[tokio::test]
 async fn enqueue_primary_thread_session_replays_buffered_approval_after_attach() -> Result<()> {
     let (mut app, mut app_event_rx, _op_rx) = make_test_app_with_channels().await;
diff --git a/codex-rs/tui/src/external_editor.rs b/codex-rs/tui/src/external_editor.rs
index 2818503d03..8639e5d15e 100644
--- a/codex-rs/tui/src/external_editor.rs
+++ b/codex-rs/tui/src/external_editor.rs
@@ -1,7 +1,14 @@
 use std::env;
 use std::fs;
+use std::path::Path;
+use std::path::PathBuf;
 use std::process::Stdio;
 
+#[cfg(windows)]
+use codex_protocol::permissions::FileSystemPath;
+use codex_protocol::permissions::FileSystemSandboxPolicy;
+#[cfg(windows)]
+use codex_protocol::permissions::FileSystemSpecialPath;
 use color_eyre::eyre::Report;
 use color_eyre::eyre::Result;
 use tempfile::Builder;
@@ -50,14 +57,145 @@ pub(crate) fn resolve_editor_command() -> std::result::Result<Vec<String>, Edito
     Ok(parts)
 }
 
+pub(super) fn editor_directory(
+    candidate_homes: &[&Path],
+    file_system_policy: &FileSystemSandboxPolicy,
+    cwd: &Path,
+) -> Result<PathBuf> {
+    let writable_roots = file_system_policy.get_writable_roots_with_cwd(cwd);
+    #[cfg(windows)]
+    let windows_temporary_roots = if !file_system_policy.has_full_disk_write_access()
+        && file_system_policy.entries.iter().any(|entry| {
+            matches!(
+                &entry.path,
+                FileSystemPath::Special {
+                    value: FileSystemSpecialPath::Tmpdir
+                }
+            ) && entry.access.can_write()
+        }) {
+        ["TEMP", "TMP"]
+            .into_iter()
+            .filter_map(env::var_os)
+            .map(PathBuf::from)
+            .filter(|path| path.is_absolute())
+            .flat_map(|path| {
+                let canonical_path = dunce::canonicalize(&path).ok();
+                std::iter::once(path).chain(canonical_path)
+            })
+            .collect::<Vec<_>>()
+    } else {
+        Vec::new()
+    };
+    let mut error = Report::msg("editor directory must not be writable");
+    let mut rejected_writable = false;
+
+    for candidate_home in candidate_homes {
+        let canonical_home = match dunce::canonicalize(candidate_home) {
+            Ok(path) => path,
+            Err(canonicalize_error)
+                if canonicalize_error.kind() == std::io::ErrorKind::NotFound =>
+            {
+                let Some(parent) = candidate_home.parent() else {
+                    error = Report::msg("editor directory has no parent");
+                    continue;
+                };
+                let Some(name) = candidate_home.file_name() else {
+                    error = Report::msg("editor directory has no parent");
+                    continue;
+                };
+                match dunce::canonicalize(parent) {
+                    Ok(parent) => parent.join(name),
+                    Err(canonicalize_error) => {
+                        error = canonicalize_error.into();
+                        continue;
+                    }
+                }
+            }
+            Err(canonicalize_error) => {
+                error = canonicalize_error.into();
+                continue;
+            }
+        };
+        let editor_directory = canonical_home.join("editor");
+        let logical_editor_directory = candidate_home.join("editor");
+
+        if !file_system_policy.has_full_disk_write_access()
+            && [&logical_editor_directory, &editor_directory]
+                .into_iter()
+                .any(|directory| {
+                    let Some(parent) = directory.parent() else {
+                        return true;
+                    };
+                    let is_writable = file_system_policy.can_write_path_with_cwd(directory, cwd)
+                        || file_system_policy.can_write_path_with_cwd(parent, cwd)
+                        || writable_roots.iter().any(|root| {
+                            root.is_path_writable(directory)
+                                || root.root.as_path().starts_with(directory)
+                        });
+                    #[cfg(windows)]
+                    let is_writable = is_writable
+                        || windows_temporary_roots.iter().any(|root| {
+                            directory.starts_with(root)
+                                || parent.starts_with(root)
+                                || root.starts_with(directory)
+                        });
+                    is_writable
+                })
+        {
+            error = Report::msg("editor directory must not be writable");
+            rejected_writable = true;
+            continue;
+        }
+
+        if let Err(create_error) = fs::create_dir_all(&editor_directory) {
+            error = create_error.into();
+            continue;
+        }
+        match dunce::canonicalize(&editor_directory) {
+            Ok(path) if path == editor_directory => return Ok(editor_directory),
+            Ok(_) => {
+                error = Report::msg("editor directory must not contain symbolic links");
+            }
+            Err(canonicalize_error) => {
+                error = canonicalize_error.into();
+            }
+        }
+    }
+
+    if rejected_writable {
+        Err(Report::msg("editor directory must not be writable"))
+    } else {
+        Err(error)
+    }
+}
+
 /// Write `seed` to a temp file, launch the editor command, and return the updated content.
-pub(crate) async fn run_editor(seed: &str, editor_cmd: &[String]) -> Result<String> {
+pub(crate) async fn run_editor(
+    seed: &str,
+    editor_cmd: &[String],
+    codex_home: &Path,
+    file_system_policy: &FileSystemSandboxPolicy,
+    cwd: &Path,
+) -> Result<String> {
     if editor_cmd.is_empty() {
         return Err(Report::msg("editor command is empty"));
     }
 
+    let default_codex_home = dirs::home_dir().map(|home| home.join(".codex"));
+    #[cfg(any(target_os = "macos", target_os = "linux"))]
+    let project_codex_home = cwd.join(".codex");
+    let mut candidate_homes = vec![codex_home];
+    if let Some(default_codex_home) = default_codex_home.as_deref() {
+        candidate_homes.push(default_codex_home);
+    }
+    #[cfg(any(target_os = "macos", target_os = "linux"))]
+    candidate_homes.push(&project_codex_home);
+    let editor_directory = editor_directory(&candidate_homes, file_system_policy, cwd)?;
     // Convert to TempPath immediately so no file handle stays open on Windows.
-    let temp_path = Builder::new().suffix(".md").tempfile()?.into_temp_path();
+    let temp_path = Builder::new()
+        .suffix(".md")
+        .tempfile_in(editor_directory)?
+        .into_temp_path();
     fs::write(&temp_path, seed)?;
 
     let mut cmd = {
@@ -165,7 +303,14 @@ mod tests {
         fs::set_permissions(&script_path, perms).unwrap();
 
         let cmd = vec![script_path.to_string_lossy().to_string()];
-        let result = run_editor("seed", &cmd).await.unwrap();
+        let policy = FileSystemSandboxPolicy::read_only();
+        let result = run_editor("seed", &cmd, dir.path(), &policy, dir.path())
+            .await
+            .unwrap();
         assert_eq!(result, "edited".to_string());
     }
 }
+
+#[cfg(test)]
+#[path = "external_editor_tests.rs"]
+mod buffer_tests;
diff --git a/codex-rs/tui/src/external_editor_tests.rs b/codex-rs/tui/src/external_editor_tests.rs
new file mode 100644
index 0000000000..575221dcf2
--- /dev/null
+++ b/codex-rs/tui/src/external_editor_tests.rs
@@ -0,0 +1,360 @@
+use super::editor_directory;
+#[cfg(unix)]
+use super::run_editor;
+use codex_protocol::permissions::FileSystemAccessMode;
+use codex_protocol::permissions::FileSystemSandboxEntry;
+use codex_protocol::permissions::FileSystemSandboxPolicy;
+use codex_utils_absolute_path::AbsolutePathBuf;
+use pretty_assertions::assert_eq;
+use std::fs;
+use std::path::Path;
+use std::path::PathBuf;
+use tempfile::TempDir;
+
+struct EditorPaths {
+    _root: TempDir,
+    codex_home: PathBuf,
+    cwd: PathBuf,
+}
+
+impl EditorPaths {
+    fn new() -> Self {
+        let root = tempfile::tempdir().expect("create editor test root");
+        let canonical_root =
+            dunce::canonicalize(root.path()).expect("canonicalize editor test root");
+        let codex_home = canonical_root.join("codex-home");
+        let cwd = canonical_root.join("workspace");
+        fs::create_dir(&codex_home).expect("create Codex home");
+        fs::create_dir(&cwd).expect("create workspace");
+
+        Self {
+            _root: root,
+            codex_home,
+            cwd,
+        }
+    }
+}
+
+fn workspace_write_policy(writable_roots: &[&Path]) -> FileSystemSandboxPolicy {
+    let writable_roots = writable_roots
+        .iter()
+        .map(|root| AbsolutePathBuf::from_absolute_path(root).expect("absolute writable root"))
+        .collect::<Vec<_>>();
+
+    FileSystemSandboxPolicy::workspace_write(
+        &writable_roots,
+        /*exclude_tmpdir_env_var*/ true,
+        /*exclude_slash_tmp*/ true,
+    )
+}
+
+#[test]
+fn editor_directory_is_inside_isolated_codex_home() {
+    let paths = EditorPaths::new();
+    let policy = workspace_write_policy(&[]);
+
+    let directory = editor_directory(&[&paths.codex_home], &policy, &paths.cwd)
+        .expect("create isolated editor directory");
+
+    assert_eq!(directory, paths.codex_home.join("editor"));
+    assert!(directory.is_dir());
+}
+
+#[test]
+fn editor_directory_rejects_writable_home_editor_and_parent() {
+    let paths = EditorPaths::new();
+    let editor = paths.codex_home.join("editor");
+    fs::create_dir(&editor).expect("create editor directory");
+    let parent = paths.codex_home.parent().expect("Codex home parent");
+
+    for writable_root in [paths.codex_home.as_path(), editor.as_path(), parent] {
+        let policy = workspace_write_policy(&[writable_root]);
+
+        assert!(
+            editor_directory(&[&paths.codex_home], &policy, &paths.cwd).is_err(),
+            "writable root {} must not expose editor buffers",
+            writable_root.display()
+        );
+    }
+}
+
+#[test]
+fn editor_directory_rejects_writable_descendant() {
+    let paths = EditorPaths::new();
+    let writable_descendant = paths.codex_home.join("editor").join("nested");
+    fs::create_dir_all(&writable_descendant).expect("create writable editor descendant");
+    let policy = workspace_write_policy(&[&writable_descendant]);
+
+    assert!(editor_directory(&[&paths.codex_home], &policy, &paths.cwd).is_err());
+}
+
+#[test]
+fn editor_directory_rejects_read_only_carveout_with_writable_parent() {
+    let paths = EditorPaths::new();
+    let editor = paths.codex_home.join("editor");
+    fs::create_dir(&editor).expect("create editor directory");
+    let policy = FileSystemSandboxPolicy::restricted(vec![
+        FileSystemSandboxEntry::new(
+            AbsolutePathBuf::from_absolute_path(&paths.codex_home)
+                .expect("absolute Codex home")
+                .into(),
+            FileSystemAccessMode::Write,
+        ),
+        FileSystemSandboxEntry::new(
+            AbsolutePathBuf::from_absolute_path(&editor)
+                .expect("absolute editor directory")
+                .into(),
+            FileSystemAccessMode::Read,
+        ),
+    ]);
+
+    assert!(editor_directory(&[&paths.codex_home], &policy, &paths.cwd).is_err());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_rejects_preexisting_symlink() {
+    use std::os::unix::fs::symlink;
+
+    let paths = EditorPaths::new();
+    let outside = paths.cwd.join("outside");
+    fs::create_dir(&outside).expect("create editor symlink target");
+    symlink(&outside, paths.codex_home.join("editor")).expect("create editor directory symlink");
+    let policy = FileSystemSandboxPolicy::read_only();
+
+    assert!(editor_directory(&[&paths.codex_home], &policy, &paths.cwd).is_err());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_rejects_writable_codex_home_alias() {
+    use std::os::unix::fs::symlink;
+
+    let paths = EditorPaths::new();
+    let aliased_home = paths.cwd.join("codex-home-link");
+    symlink(&paths.codex_home, &aliased_home).expect("create Codex home symlink");
+    let policy = workspace_write_policy(&[]);
+
+    assert!(policy.can_write_path_with_cwd(&aliased_home.join("editor"), &paths.cwd));
+    assert!(!policy.can_write_path_with_cwd(&paths.codex_home.join("editor"), &paths.cwd));
+    assert!(editor_directory(&[&aliased_home], &policy, &paths.cwd).is_err());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_rejects_writable_codex_home_alias_target() {
+    use std::os::unix::fs::symlink;
+
+    let paths = EditorPaths::new();
+    let alias_parent = paths
+        .codex_home
+        .parent()
+        .expect("Codex home parent")
+        .join("aliases");
+    fs::create_dir(&alias_parent).expect("create protected alias parent");
+    let aliased_home = alias_parent.join("codex-home-link");
+    symlink(&paths.codex_home, &aliased_home).expect("create Codex home symlink");
+    let policy = workspace_write_policy(&[&paths.codex_home]);
+
+    assert!(!policy.can_write_path_with_cwd(&aliased_home.join("editor"), &paths.cwd));
+    assert!(policy.can_write_path_with_cwd(&paths.codex_home.join("editor"), &paths.cwd));
+    assert!(editor_directory(&[&aliased_home], &policy, &paths.cwd).is_err());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_uses_protected_workspace_fallback_with_default_temporary_grants() {
+    let root = tempfile::tempdir().expect("create editor test root");
+    let codex_home = root.path().join("codex-home");
+    let cwd = root.path().join("workspace");
+    fs::create_dir(&codex_home).expect("create Codex home");
+    fs::create_dir(&cwd).expect("create workspace");
+    let workspace_codex_home = cwd.join(".codex");
+    let policy = FileSystemSandboxPolicy::workspace_write(
+        &[],
+        /*exclude_tmpdir_env_var*/ false,
+        /*exclude_slash_tmp*/ false,
+    );
+
+    assert!(!workspace_codex_home.exists());
+    assert!(policy.can_write_path_with_cwd(&codex_home, &cwd));
+    assert!(!policy.can_write_path_with_cwd(&workspace_codex_home, &cwd));
+    assert!(!policy.can_write_path_with_cwd(&workspace_codex_home.join("editor"), &cwd));
+
+    let directory = editor_directory(&[&codex_home, &workspace_codex_home], &policy, &cwd)
+        .expect("use protected workspace metadata directory");
+
+    assert_eq!(
+        directory,
+        dunce::canonicalize(&workspace_codex_home)
+            .expect("canonicalize workspace metadata directory")
+            .join("editor")
+    );
+    assert!(directory.is_dir());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_rejects_explicitly_writable_workspace_fallback() {
+    let root = tempfile::tempdir().expect("create editor test root");
+    let codex_home = root.path().join("codex-home");
+    let cwd = root.path().join("workspace");
+    fs::create_dir(&codex_home).expect("create Codex home");
+    fs::create_dir(&cwd).expect("create workspace");
+    let workspace_codex_home = cwd.join(".codex");
+    let writable_workspace_codex_home = AbsolutePathBuf::from_absolute_path(&workspace_codex_home)
+        .expect("absolute workspace metadata directory");
+    let policy = FileSystemSandboxPolicy::workspace_write(
+        &[writable_workspace_codex_home],
+        /*exclude_tmpdir_env_var*/ false,
+        /*exclude_slash_tmp*/ false,
+    );
+
+    assert!(policy.can_write_path_with_cwd(&codex_home, &cwd));
+    assert!(policy.can_write_path_with_cwd(&workspace_codex_home, &cwd));
+    assert!(
+        editor_directory(&[&codex_home, &workspace_codex_home], &policy, &cwd).is_err(),
+        "explicitly writable metadata must not be used for editor buffers"
+    );
+    assert!(!workspace_codex_home.exists());
+}
+
+#[test]
+#[cfg(unix)]
+fn editor_directory_rejects_workspace_fallback_symlink_to_writable_target() {
+    use std::os::unix::fs::symlink;
+
+    let paths = EditorPaths::new();
+    let workspace_codex_home = paths.cwd.join(".codex");
+    symlink(&paths.codex_home, &workspace_codex_home).expect("create workspace metadata symlink");
+    let policy = workspace_write_policy(&[&paths.codex_home]);
+
+    assert!(!policy.can_write_path_with_cwd(&workspace_codex_home, &paths.cwd));
+    assert!(policy.can_write_path_with_cwd(&paths.codex_home, &paths.cwd));
+    assert!(
+        editor_directory(
+            &[&paths.codex_home, &workspace_codex_home],
+            &policy,
+            &paths.cwd,
+        )
+        .is_err()
+    );
+}
+
+#[test]
+fn editor_directory_uses_next_protected_candidate_after_creation_error() {
+    let paths = EditorPaths::new();
+    let unavailable_home = paths
+        .codex_home
+        .parent()
+        .expect("Codex home parent")
+        .join("unavailable-home");
+    fs::write(&unavailable_home, "not a directory").expect("create unavailable Codex home");
+    let policy = workspace_write_policy(&[]);
+
+    let directory = editor_directory(&[&unavailable_home, &paths.codex_home], &policy, &paths.cwd)
+        .expect("use next protected candidate after directory creation fails");
+
+    assert_eq!(directory, paths.codex_home.join("editor"));
+}
+
+#[test]
+#[cfg(windows)]
+fn editor_directory_rejects_windows_temporary_directory_outside_tmpdir_policy_root() {
+    let paths = EditorPaths::new();
+    let policy = FileSystemSandboxPolicy::workspace_write(
+        &[],
+        /*exclude_tmpdir_env_var*/ false,
+        /*exclude_slash_tmp*/ true,
+    );
+
+    assert!(
+        editor_directory(&[&paths.codex_home], &policy, &paths.cwd).is_err(),
+        "effective Windows temporary directories must not contain editor buffers"
+    );
+    assert!(!paths.codex_home.join("editor").exists());
+}
+
+#[test]
+fn editor_directory_allows_full_disk_write_policies() {
+    let paths = EditorPaths::new();
+
+    for policy in [
+        FileSystemSandboxPolicy::unrestricted(),
+        FileSystemSandboxPolicy::external_sandbox(),
+    ] {
+        let directory = editor_directory(&[&paths.codex_home], &policy, &paths.cwd)
+            .expect("full-disk-write policies should preserve external editor support");
+
+        assert_eq!(directory, paths.codex_home.join("editor"));
+    }
+}
+
+#[tokio::test]
+#[cfg(unix)]
+async fn editor_process_receives_buffer_in_isolated_codex_home() {
+    let paths = EditorPaths::new();
+    let policy = workspace_write_policy(&[]);
+    let editor_directory = paths.codex_home.join("editor");
+    let editor_command = vec![
+        "/bin/sh".to_string(),
+        "-c".to_string(),
+        "case \"$2\" in \"$1\"/*) printf edited > \"$2\" ;; *) exit 88 ;; esac".to_string(),
+        "editor".to_string(),
+        editor_directory.to_string_lossy().into_owned(),
+    ];
+
+    let content = run_editor(
+        "seed",
+        &editor_command,
+        &paths.codex_home,
+        &policy,
+        &paths.cwd,
+    )
+    .await
+    .expect("run editor with isolated buffer");
+
+    assert_eq!(content, "edited");
+}
+
+#[tokio::test]
+#[cfg(any(target_os = "macos", target_os = "linux"))]
+async fn editor_process_uses_protected_workspace_fallback_with_default_temporary_grants() {
+    let root = tempfile::tempdir().expect("create editor test root");
+    let codex_home = root.path().join("codex-home");
+    let cwd = root.path().join("workspace");
+    fs::create_dir(&codex_home).expect("create Codex home");
+    fs::create_dir(&cwd).expect("create workspace");
+    let default_codex_home = dirs::home_dir().expect("home directory").join(".codex");
+    let writable_default_codex_home = AbsolutePathBuf::from_absolute_path(&default_codex_home)
+        .expect("absolute default Codex home");
+    let policy = FileSystemSandboxPolicy::workspace_write(
+        &[writable_default_codex_home],
+        /*exclude_tmpdir_env_var*/ false,
+        /*exclude_slash_tmp*/ false,
+    );
+    let workspace_codex_home = cwd.join(".codex");
+    let editor_directory = dunce::canonicalize(&cwd)
+        .expect("canonicalize workspace")
+        .join(".codex")
+        .join("editor");
+    let editor_command = vec![
+        "/bin/sh".to_string(),
+        "-c".to_string(),
+        "case \"$2\" in \"$1\"/*) printf edited > \"$2\" ;; *) exit 88 ;; esac".to_string(),
+        "editor".to_string(),
+        editor_directory.to_string_lossy().into_owned(),
+    ];
+
+    assert!(!workspace_codex_home.exists());
+    assert!(policy.can_write_path_with_cwd(&codex_home, &cwd));
+    assert!(policy.can_write_path_with_cwd(&default_codex_home, &cwd));
+    assert!(!policy.can_write_path_with_cwd(&workspace_codex_home, &cwd));
+
+    let content = run_editor("seed", &editor_command, &codex_home, &policy, &cwd)
+        .await
+        .expect("run editor with protected workspace fallback");
+
+    assert_eq!(content, "edited");
+    assert!(editor_directory.is_dir());
+}
diff --git a/codex-rs/tui/src/snapshots/codex_tui__app__tests__external_editor_writable_directory_rejected.snap b/codex-rs/tui/src/snapshots/codex_tui__app__tests__external_editor_writable_directory_rejected.snap
new file mode 100644
index 0000000000..ac46c12a6c
--- /dev/null
+++ b/codex-rs/tui/src/snapshots/codex_tui__app__tests__external_editor_writable_directory_rejected.snap
@@ -0,0 +1,5 @@
+---
+source: tui/src/app/tests.rs
+expression: rendered
+---
+■ Failed to open editor: editor directory must not be writable