diff --git a/codex-rs/app-server-protocol/src/protocol/v2/permissions.rs b/codex-rs/app-server-protocol/src/protocol/v2/permissions.rs
index 932e44e267..d1d7c680f6 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2/permissions.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2/permissions.rs
@@ -23,7 +23,7 @@ use serde::Deserialize;
 use serde::Serialize;
 use std::io;
 use std::num::NonZeroUsize;
-use std::path::PathBuf;
+use std::path::Path;
 use ts_rs::TS;
 
 v2_enum_from_core! {
@@ -244,13 +244,13 @@ pub enum FileSystemSpecialPath {
     Minimal,
     #[serde(alias = "current_working_directory")]
     ProjectRoots {
-        subpath: Option<PathBuf>,
+        subpath: Option<LegacyAppPathString>,
     },
     Tmpdir,
     SlashTmp,
     Unknown {
         path: String,
-        subpath: Option<PathBuf>,
+        subpath: Option<LegacyAppPathString>,
     },
 }
 
@@ -259,10 +259,21 @@ impl From<CoreFileSystemSpecialPath> for FileSystemSpecialPath {
         match value {
             CoreFileSystemSpecialPath::Root => Self::Root,
             CoreFileSystemSpecialPath::Minimal => Self::Minimal,
-            CoreFileSystemSpecialPath::ProjectRoots { subpath } => Self::ProjectRoots { subpath },
+            CoreFileSystemSpecialPath::ProjectRoots { subpath } => Self::ProjectRoots {
+                subpath: subpath
+                    .as_deref()
+                    .map(Path::new)
+                    .map(LegacyAppPathString::from_path),
+            },
             CoreFileSystemSpecialPath::Tmpdir => Self::Tmpdir,
             CoreFileSystemSpecialPath::SlashTmp => Self::SlashTmp,
-            CoreFileSystemSpecialPath::Unknown { path, subpath } => Self::Unknown { path, subpath },
+            CoreFileSystemSpecialPath::Unknown { path, subpath } => Self::Unknown {
+                path,
+                subpath: subpath
+                    .as_deref()
+                    .map(Path::new)
+                    .map(LegacyAppPathString::from_path),
+            },
         }
     }
 }
@@ -272,10 +283,15 @@ impl From<FileSystemSpecialPath> for CoreFileSystemSpecialPath {
         match value {
             FileSystemSpecialPath::Root => Self::Root,
             FileSystemSpecialPath::Minimal => Self::Minimal,
-            FileSystemSpecialPath::ProjectRoots { subpath } => Self::ProjectRoots { subpath },
+            FileSystemSpecialPath::ProjectRoots { subpath } => Self::ProjectRoots {
+                subpath: subpath.map(LegacyAppPathString::into_string),
+            },
             FileSystemSpecialPath::Tmpdir => Self::Tmpdir,
             FileSystemSpecialPath::SlashTmp => Self::SlashTmp,
-            FileSystemSpecialPath::Unknown { path, subpath } => Self::Unknown { path, subpath },
+            FileSystemSpecialPath::Unknown { path, subpath } => Self::Unknown {
+                path,
+                subpath: subpath.map(LegacyAppPathString::into_string),
+            },
         }
     }
 }
diff --git a/codex-rs/core/src/config/permissions.rs b/codex-rs/core/src/config/permissions.rs
index 9c6d3ed725..88ee6f4e77 100644
--- a/codex-rs/core/src/config/permissions.rs
+++ b/codex-rs/core/src/config/permissions.rs
@@ -274,7 +274,7 @@ fn insert_special_filesystem_permission_toml(
             insert_scoped_filesystem_permission_toml(
                 entries,
                 ":workspace_roots".to_string(),
-                subpath.unwrap_or_else(|| PathBuf::from(".")),
+                subpath.unwrap_or_else(|| ".".to_string()),
                 access,
             );
         }
@@ -303,7 +303,7 @@ fn insert_special_filesystem_permission_toml(
 fn insert_scoped_filesystem_permission_toml(
     entries: &mut BTreeMap<String, FilesystemPermissionToml>,
     path: String,
-    subpath: PathBuf,
+    subpath: String,
     access: FileSystemAccessMode,
 ) {
     let permission = entries
@@ -311,13 +311,10 @@ fn insert_scoped_filesystem_permission_toml(
         .or_insert_with(|| FilesystemPermissionToml::Scoped(BTreeMap::new()));
     match permission {
         FilesystemPermissionToml::Scoped(scoped_entries) => {
-            scoped_entries.insert(subpath.to_string_lossy().into_owned(), access);
+            scoped_entries.insert(subpath, access);
         }
         FilesystemPermissionToml::Access(_) => {
-            *permission = FilesystemPermissionToml::Scoped(BTreeMap::from([(
-                subpath.to_string_lossy().into_owned(),
-                access,
-            )]));
+            *permission = FilesystemPermissionToml::Scoped(BTreeMap::from([(subpath, access)]));
         }
     }
 }
@@ -608,7 +605,9 @@ fn compile_scoped_filesystem_path(
     }
 
     if let Some(special) = parse_special_path(path) {
-        let subpath = parse_relative_subpath(subpath)?;
+        let subpath = parse_relative_subpath(subpath)?
+            .to_string_lossy()
+            .into_owned();
         let special = match special {
             FileSystemSpecialPath::ProjectRoots { .. } => Ok(FileSystemPath::Special {
                 value: FileSystemSpecialPath::project_roots(Some(subpath)),
@@ -894,8 +893,7 @@ fn maybe_push_unknown_special_path_warning(
         startup_warnings,
         match subpath.as_deref() {
             Some(subpath) => format!(
-                "Configured filesystem path `{path}` with nested entry `{}` is not recognized by this version of Codex and will be ignored. Upgrade Codex if this path is required.",
-                subpath.display()
+                "Configured filesystem path `{path}` with nested entry `{subpath}` is not recognized by this version of Codex and will be ignored. Upgrade Codex if this path is required."
             ),
             None => format!(
                 "Configured filesystem path `{path}` is not recognized by this version of Codex and will be ignored. Upgrade Codex if this path is required."
diff --git a/codex-rs/core/src/context/environment_context.rs b/codex-rs/core/src/context/environment_context.rs
index 2f795a8ea3..2117231f08 100644
--- a/codex-rs/core/src/context/environment_context.rs
+++ b/codex-rs/core/src/context/environment_context.rs
@@ -6,7 +6,6 @@ use codex_protocol::permissions::FileSystemSandboxEntry;
 use codex_protocol::permissions::FileSystemSpecialPath;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use std::collections::HashSet;
-use std::path::PathBuf;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub(crate) struct FileSystemContext {
@@ -179,9 +178,9 @@ fn render_special_path(value: &FileSystemSpecialPath) -> String {
     }
 }
 
-fn render_special_path_with_subpath(base: &str, subpath: &Option<PathBuf>) -> String {
+fn render_special_path_with_subpath(base: &str, subpath: &Option<String>) -> String {
     match subpath {
-        Some(subpath) => format!("{base}/{}", subpath.display()),
+        Some(subpath) => format!("{base}/{subpath}"),
         None => base.to_string(),
     }
 }
diff --git a/codex-rs/core/src/context/world_state/environment_render_tests.rs b/codex-rs/core/src/context/world_state/environment_render_tests.rs
index 70122586ed..3093680676 100644
--- a/codex-rs/core/src/context/world_state/environment_render_tests.rs
+++ b/codex-rs/core/src/context/world_state/environment_render_tests.rs
@@ -14,12 +14,11 @@ use codex_utils_absolute_path::test_support::PathBufExt;
 use core_test_support::test_path_buf;
 use pretty_assertions::assert_eq;
 use std::path::Path;
-use std::path::PathBuf;
 
 fn fake_shell_name() -> String {
     let shell = crate::shell::Shell {
         shell_type: ShellType::Bash,
-        shell_path: PathBuf::from("/bin/bash"),
+        shell_path: "/bin/bash".to_string(),
     };
     shell.name().to_string()
 }
@@ -150,7 +149,7 @@ fn workspace_write_permission_profile_with_private_denials() -> PermissionProfil
             },
             FileSystemSandboxEntry {
                 path: FileSystemPath::Special {
-                    value: FileSystemSpecialPath::project_roots(Some(PathBuf::from("private"))),
+                    value: FileSystemSpecialPath::project_roots(Some("private".to_string())),
                 },
                 access: FileSystemAccessMode::Deny,
             },
diff --git a/codex-rs/linux-sandbox/src/bwrap.rs b/codex-rs/linux-sandbox/src/bwrap.rs
index 25a3814fb5..5c72a98d7c 100644
--- a/codex-rs/linux-sandbox/src/bwrap.rs
+++ b/codex-rs/linux-sandbox/src/bwrap.rs
@@ -410,7 +410,7 @@ fn create_filesystem_args(
                 // rules should keep their normal bwrap behavior, which can mask
                 // the first missing component to prevent creation under writable
                 // roots.
-                let project_subpath = subpath.as_path();
+                let project_subpath = Path::new(subpath);
                 if project_subpath != Path::new(".git")
                     && project_subpath != Path::new(".agents")
                     && project_subpath != Path::new(".codex")
diff --git a/codex-rs/protocol/src/permissions.rs b/codex-rs/protocol/src/permissions.rs
index 5573f488e8..eba2f0e0aa 100644
--- a/codex-rs/protocol/src/permissions.rs
+++ b/codex-rs/protocol/src/permissions.rs
@@ -143,7 +143,7 @@ pub enum FileSystemSpecialPath {
     ProjectRoots {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         #[ts(optional)]
-        subpath: Option<PathBuf>,
+        subpath: Option<String>,
     },
     Tmpdir,
     SlashTmp,
@@ -159,16 +159,16 @@ pub enum FileSystemSpecialPath {
         path: String,
         #[serde(default, skip_serializing_if = "Option::is_none")]
         #[ts(optional)]
-        subpath: Option<PathBuf>,
+        subpath: Option<String>,
     },
 }
 
 impl FileSystemSpecialPath {
-    pub fn project_roots(subpath: Option<PathBuf>) -> Self {
+    pub fn project_roots(subpath: Option<String>) -> Self {
         Self::ProjectRoots { subpath }
     }
 
-    pub fn unknown(path: impl Into<String>, subpath: Option<PathBuf>) -> Self {
+    pub fn unknown(path: impl Into<String>, subpath: Option<String>) -> Self {
         Self::Unknown {
             path: path.into(),
             subpath,
@@ -1712,7 +1712,7 @@ fn legacy_runtime_file_system_policy_for_cwd(
 
 fn append_default_read_only_project_root_subpath_if_no_explicit_rule(
     entries: &mut Vec<FileSystemSandboxEntry>,
-    subpath: impl Into<PathBuf>,
+    subpath: impl Into<String>,
 ) {
     append_default_read_only_entry_if_no_explicit_rule(
         entries,
diff --git a/codex-rs/tui/src/bottom_pane/approval_overlay.rs b/codex-rs/tui/src/bottom_pane/approval_overlay.rs
index 3cc135da74..8a13667ed5 100644
--- a/codex-rs/tui/src/bottom_pane/approval_overlay.rs
+++ b/codex-rs/tui/src/bottom_pane/approval_overlay.rs
@@ -1028,9 +1028,9 @@ fn special_path_label(value: &FileSystemSpecialPath) -> String {
     }
 }
 
-fn path_label(base: &str, subpath: &Option<PathBuf>) -> String {
+fn path_label(base: &str, subpath: &Option<String>) -> String {
     match subpath {
-        Some(subpath) => format!("{base}/{}", subpath.display()),
+        Some(subpath) => format!("{base}/{subpath}"),
         None => base.to_string(),
     }
 }