diff --git a/codex-rs/core/src/environment_selection.rs b/codex-rs/core/src/environment_selection.rs
index 3d3989eb73..bbd04e9657 100644
--- a/codex-rs/core/src/environment_selection.rs
+++ b/codex-rs/core/src/environment_selection.rs
@@ -8,6 +8,7 @@ use arc_swap::ArcSwap;
 use async_channel::Sender;
 use codex_exec_server::Environment;
 use codex_exec_server::EnvironmentConnectionState;
+use codex_exec_server::EnvironmentInfo;
 use codex_exec_server::EnvironmentManager;
 use codex_exec_server::ExecServerError;
 use codex_exec_server::ExecutorFileSystem;
@@ -136,6 +137,7 @@ type PendingConfigurationResult = Result<EnvironmentConfig, String>;
 struct ResolvedEnvironment {
     environment: Arc<Environment>,
     shell: Option<Shell>,
+    temporary_directories: Option<Vec<PathUri>>,
     shell_snapshot: ShellSnapshotTask,
     shell_snapshot_v2_supported: bool,
     installed_config: Option<EnvironmentConfig>,
@@ -239,6 +241,7 @@ impl ThreadEnvironments {
                     futures::future::ready(Ok(ResolvedEnvironment {
                         environment: environment.environment,
                         shell: environment.shell,
+                        temporary_directories: environment.temporary_directories,
                         shell_snapshot: environment.shell_snapshot,
                         shell_snapshot_v2_supported: environment.shell_snapshot_v2_supported,
                         installed_config: None,
@@ -604,10 +607,13 @@ impl ThreadEnvironments {
         };
         // Resolve the attachment only after both prerequisites are ready.
         let ((), installed_config) = tokio::try_join!(connection_ready, configuration_ready)?;
-        let (shell, shell_snapshot_v2_supported) = if environment.is_remote() {
+        let (shell, temporary_directories, shell_snapshot_v2_supported) = if environment.is_remote()
+        {
             match environment.info().await {
-                Ok(info) => (
-                    match Shell::from_environment_shell_info(info.shell) {
+                Ok(info) => {
+                    let temporary_directories = info.temporary_directories;
+                    let shell_snapshot_v2_supported = info.capabilities.shell_snapshot_v2;
+                    let shell = match Shell::from_environment_shell_info(info.shell) {
                         Ok(shell) => Some(shell),
                         Err(err) => {
                             tracing::warn!(
@@ -615,16 +621,20 @@ impl ThreadEnvironments {
                             );
                             None
                         }
-                    },
-                    info.capabilities.shell_snapshot_v2,
-                ),
+                    };
+                    (shell, temporary_directories, shell_snapshot_v2_supported)
+                }
                 Err(err) => {
                     tracing::warn!("failed to get info for environment `{environment_id}`: {err}");
-                    (None, false)
+                    (None, None, false)
                 }
             }
         } else {
-            (Some(local_shell), cfg!(unix))
+            (
+                Some(local_shell),
+                Some(EnvironmentInfo::local_temporary_directories()),
+                cfg!(unix),
+            )
         };
         let task = shell_snapshot
             .build(Arc::clone(&environment), selection.cwd, shell.clone())
@@ -636,6 +646,7 @@ impl ThreadEnvironments {
         Ok(ResolvedEnvironment {
             environment,
             shell,
+            temporary_directories,
             shell_snapshot: task,
             shell_snapshot_v2_supported,
             installed_config,
@@ -715,6 +726,7 @@ impl TurnEnvironmentState {
                 turn_environment.shell_snapshot = environment.shell_snapshot;
                 turn_environment.shell_snapshot_v2_supported =
                     environment.shell_snapshot_v2_supported;
+                turn_environment.temporary_directories = environment.temporary_directories;
                 Some(Self::Ready(turn_environment))
             }
             Some(Err(err)) => {
@@ -881,6 +893,7 @@ mod tests {
     use codex_protocol::config_types::WindowsSandboxLevel;
     use codex_protocol::models::ActivePermissionProfile;
     use codex_protocol::models::PermissionProfile;
+    use codex_protocol::permissions::FileSystemSandboxPolicyContext;
     use codex_protocol::protocol::TurnEnvironmentSelection;
     use codex_utils_absolute_path::AbsolutePathBuf;
     use codex_utils_path_uri::PathUri;
@@ -986,7 +999,10 @@ mod tests {
             .send(Message::Text(
                 serde_json::json!({
                     "id": info["id"],
-                    "result": { "shell": { "name": "zsh", "path": "/bin/zsh" } }
+                    "result": {
+                        "shell": { "name": "zsh", "path": "/bin/zsh" },
+                        "temporaryDirectories": ["file:///tmp/remote"],
+                    }
                 })
                 .to_string()
                 .into(),
@@ -1111,9 +1127,21 @@ url = "ws://127.0.0.1:8765"
 
         let snapshot = turn_environments.snapshot().await;
         let environment = snapshot.primary().expect("local environment");
+        let expected_temporary_directories = EnvironmentInfo::local_temporary_directories();
 
         assert_eq!(environment.shell.as_ref(), Some(&local_shell));
         assert_eq!(environment.config(), &expected_config);
+        assert_eq!(
+            environment
+                .sandbox_context(/*additional_permissions*/ None)
+                .policy_context()
+                .expect("selected environment sandbox context has cwd"),
+            FileSystemSandboxPolicyContext {
+                cwd: environment.cwd(),
+                workspace_roots: &[],
+                temporary_directories: Some(expected_temporary_directories.as_slice()),
+            }
+        );
     }
 
     #[tokio::test]
@@ -1424,6 +1452,20 @@ url = "ws://127.0.0.1:8765"
             vec![expected_config.clone(), expected_config]
         );
         assert_eq!(attached.to_selections(), vec![remote, local]);
+        let environment = attached.primary().expect("remote environment");
+        let expected_temporary_directories =
+            [PathUri::parse("file:///tmp/remote").expect("remote temporary directory")];
+        assert_eq!(
+            environment
+                .sandbox_context(/*additional_permissions*/ None)
+                .policy_context()
+                .expect("selected environment sandbox context has cwd"),
+            FileSystemSandboxPolicyContext {
+                cwd: environment.cwd(),
+                workspace_roots: &[],
+                temporary_directories: Some(expected_temporary_directories.as_slice()),
+            }
+        );
         assert_eq!(
             next_starting
                 .refresh_readiness()
@@ -1637,7 +1679,7 @@ url = "ws://127.0.0.1:8765"
             Environment::create_for_tests(Some("ws://127.0.0.1:8765".to_string()))
                 .expect("inherited environment"),
         );
-        let inherited = TurnEnvironment::new(
+        let mut inherited = TurnEnvironment::new(
             TurnEnvironmentSelection {
                 config: EnvironmentConfigState::Ready(test_environment_config()),
                 ..selection.clone()
@@ -1646,6 +1688,9 @@ url = "ws://127.0.0.1:8765"
             Arc::clone(&inherited_environment),
             /*shell*/ None,
         );
+        inherited.temporary_directories = Some(vec![
+            PathUri::parse("file:///tmp/inherited").expect("temporary directory"),
+        ]);
         let manager = Arc::new(environment_manager_without_environments());
         manager
             .upsert_environment(
@@ -1687,6 +1732,15 @@ url = "ws://127.0.0.1:8765"
         let inherited = snapshot.primary().expect("inherited environment");
         assert!(Arc::ptr_eq(&inherited.environment, &inherited_environment));
         assert_eq!(inherited.config(), &child_config);
+        assert_eq!(
+            inherited
+                .sandbox_context(/*additional_permissions*/ None)
+                .temporary_directories
+                .as_deref(),
+            Some(
+                [PathUri::parse("file:///tmp/inherited").expect("temporary directory")].as_slice()
+            )
+        );
     }
 
     #[tokio::test]
diff --git a/codex-rs/core/src/session/tests.rs b/codex-rs/core/src/session/tests.rs
index e9af213209..b988a09c89 100644
--- a/codex-rs/core/src/session/tests.rs
+++ b/codex-rs/core/src/session/tests.rs
@@ -9103,6 +9103,7 @@ async fn capability_discovery_uses_environment_permission_profile() {
         permissions: environment.permission_profile().clone().into(),
         cwd: Some(environment.cwd().clone()),
         workspace_roots: environment.workspace_roots().to_vec(),
+        temporary_directories: environment.temporary_directories.clone(),
         windows_sandbox_level: WindowsSandboxLevel::Elevated,
         windows_sandbox_private_desktop: false,
         windows_sandbox_proxy_settings_mode: None,
diff --git a/codex-rs/core/src/session/turn_context.rs b/codex-rs/core/src/session/turn_context.rs
index 7782e070d0..9cffab37bf 100644
--- a/codex-rs/core/src/session/turn_context.rs
+++ b/codex-rs/core/src/session/turn_context.rs
@@ -43,6 +43,8 @@ pub(crate) struct TurnEnvironment {
     pub(crate) selection: TurnEnvironmentSelection,
     pub(crate) config_origin: EnvironmentConfigOrigin,
     pub(crate) environment: Arc<Environment>,
+    /// Cached from the selected executor; `None` means it did not report them.
+    pub(crate) temporary_directories: Option<Vec<PathUri>>,
     pub(crate) shell: Option<shell::Shell>,
     pub(crate) shell_snapshot: ShellSnapshotTask,
     pub(crate) shell_snapshot_v2_supported: bool,
@@ -60,6 +62,7 @@ impl TurnEnvironment {
             selection,
             config_origin,
             environment,
+            temporary_directories: None,
             shell,
             shell_snapshot: futures::future::ready(None).boxed().shared(),
             shell_snapshot_v2_supported: false,
@@ -123,6 +126,7 @@ impl TurnEnvironment {
             permissions: permissions.into(),
             cwd: Some(self.cwd().clone()),
             workspace_roots: self.workspace_roots().to_vec(),
+            temporary_directories: self.temporary_directories.clone(),
             windows_sandbox_level: executor_windows_sandbox_level(
                 config.windows_sandbox_level,
                 self.cwd(),
@@ -161,6 +165,7 @@ impl std::fmt::Debug for TurnEnvironment {
             .field("environment", &self.environment)
             .field("cwd", &self.selection.cwd)
             .field("workspace_roots", &self.selection.workspace_roots)
+            .field("temporary_directories", &self.temporary_directories)
             .field("shell", &self.shell)
             .field("config", self.config())
             .field("config_origin", &self.config_origin)
diff --git a/codex-rs/core/src/tools/runtimes/apply_patch.rs b/codex-rs/core/src/tools/runtimes/apply_patch.rs
index 4446a0da08..7df1946569 100644
--- a/codex-rs/core/src/tools/runtimes/apply_patch.rs
+++ b/codex-rs/core/src/tools/runtimes/apply_patch.rs
@@ -100,6 +100,7 @@ impl ApplyPatchRuntime {
             permissions: permissions.into(),
             cwd: Some(attempt.sandbox_cwd.clone()),
             workspace_roots: attempt.workspace_roots.to_vec(),
+            temporary_directories: None,
             windows_sandbox_level: executor_windows_sandbox_level(
                 attempt.windows_sandbox_level,
                 attempt.sandbox_cwd,
diff --git a/codex-rs/core/src/tools/runtimes/apply_patch_tests.rs b/codex-rs/core/src/tools/runtimes/apply_patch_tests.rs
index 8ca3883e65..3a5e64d1a1 100644
--- a/codex-rs/core/src/tools/runtimes/apply_patch_tests.rs
+++ b/codex-rs/core/src/tools/runtimes/apply_patch_tests.rs
@@ -344,6 +344,7 @@ async fn file_system_sandbox_context_respects_sandbox_request() {
             permissions: permissions.into(),
             cwd: Some(cwd.clone()),
             workspace_roots: vec![cwd],
+            temporary_directories: None,
             windows_sandbox_level: WindowsSandboxLevel::RestrictedToken,
             windows_sandbox_private_desktop: false,
             windows_sandbox_proxy_settings_mode: None,
diff --git a/codex-rs/core/src/tools/sandboxing.rs b/codex-rs/core/src/tools/sandboxing.rs
index aa665c4633..274497009d 100644
--- a/codex-rs/core/src/tools/sandboxing.rs
+++ b/codex-rs/core/src/tools/sandboxing.rs
@@ -502,6 +502,7 @@ impl<'a> SandboxAttempt<'a> {
                 permissions: exec_server_permissions.into(),
                 cwd: Some(exec_request.windows_sandbox_policy_cwd.clone()),
                 workspace_roots: self.workspace_roots.to_vec(),
+                temporary_directories: None,
                 windows_sandbox_level: executor_windows_sandbox_level(
                     self.windows_sandbox_level,
                     self.sandbox_cwd,
diff --git a/codex-rs/core/src/tools/sandboxing_tests.rs b/codex-rs/core/src/tools/sandboxing_tests.rs
index e9098509d6..5aff20e706 100644
--- a/codex-rs/core/src/tools/sandboxing_tests.rs
+++ b/codex-rs/core/src/tools/sandboxing_tests.rs
@@ -369,6 +369,7 @@ fn exec_server_env_keeps_command_native_and_carries_sandbox_context() {
             permissions: exec_server_permissions.clone().into(),
             cwd: Some(cwd_uri.clone()),
             workspace_roots: vec![cwd_uri.clone()],
+            temporary_directories: None,
             windows_sandbox_level: if cfg!(windows) {
                 codex_protocol::config_types::WindowsSandboxLevel::RestrictedToken
             } else {
diff --git a/codex-rs/exec-server-protocol/src/protocol.rs b/codex-rs/exec-server-protocol/src/protocol.rs
index 8c171eabd9..95213a63d9 100644
--- a/codex-rs/exec-server-protocol/src/protocol.rs
+++ b/codex-rs/exec-server-protocol/src/protocol.rs
@@ -153,9 +153,16 @@ pub enum EnvironmentStatusKind {
 }
 
 impl EnvironmentInfo {
-    /// Returns information about the current local exec-server process.
-    pub fn local() -> Self {
+    /// Returns executor-local default directories used to resolve `:tmpdir`.
+    ///
+    /// This is separate from `local` so orchestrator startup can cache the
+    /// directories without repeating local shell detection.
+    pub fn local_temporary_directories() -> Vec<PathUri> {
         let cwd = std::env::current_dir().ok();
+        Self::local_temporary_directories_with_cwd(cwd.as_deref())
+    }
+
+    fn local_temporary_directories_with_cwd(cwd: Option<&std::path::Path>) -> Vec<PathUri> {
         let temporary_directory_env_vars: &[&str] = if cfg!(windows) {
             &["TEMP", "TMP"]
         } else {
@@ -181,6 +188,22 @@ impl EnvironmentInfo {
                 temporary_directories.push(path);
             }
         }
+        temporary_directories
+    }
+
+    /// Returns information about the current local exec-server process.
+    pub fn local() -> Self {
+        let cwd = std::env::current_dir().ok();
+        let temporary_directories = Self::local_temporary_directories_with_cwd(cwd.as_deref());
+        let normalize_temp_path = |path: std::ffi::OsString| {
+            PathUri::from_host_native_path(&path).ok().or_else(|| {
+                if cfg!(unix) {
+                    PathUri::from_host_native_path(cwd.as_ref()?.join(path)).ok()
+                } else {
+                    None
+                }
+            })
+        };
         let temp_dir = normalize_temp_path(std::env::temp_dir().into_os_string());
 
         Self {
diff --git a/codex-rs/file-system/src/lib.rs b/codex-rs/file-system/src/lib.rs
index 2a651ca67a..a921bbd1c5 100644
--- a/codex-rs/file-system/src/lib.rs
+++ b/codex-rs/file-system/src/lib.rs
@@ -12,6 +12,7 @@ use codex_protocol::permissions::FileSystemSandboxEntry;
 use codex_protocol::permissions::FileSystemSandboxEntryMissingPathBehavior;
 use codex_protocol::permissions::FileSystemSandboxKind;
 use codex_protocol::permissions::FileSystemSandboxPolicy;
+use codex_protocol::permissions::FileSystemSandboxPolicyContext;
 use codex_protocol::permissions::FileSystemSpecialPath;
 use codex_protocol::permissions::NetworkSandboxPolicy;
 use codex_protocol::protocol::SandboxPolicy;
@@ -332,6 +333,9 @@ pub struct FileSystemSandboxContext {
     pub cwd: Option<PathUri>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub workspace_roots: Vec<PathUri>,
+    /// Executor-local default directories used to resolve `:tmpdir` policy entries.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub temporary_directories: Option<Vec<PathUri>>,
     pub windows_sandbox_level: WindowsSandboxLevel,
     #[serde(default)]
     pub windows_sandbox_private_desktop: bool,
@@ -376,6 +380,7 @@ impl FileSystemSandboxContext {
             permissions: permissions.into(),
             cwd,
             workspace_roots,
+            temporary_directories: None,
             windows_sandbox_level: WindowsSandboxLevel::Disabled,
             windows_sandbox_private_desktop: false,
             windows_sandbox_proxy_settings_mode: None,
@@ -393,6 +398,17 @@ impl FileSystemSandboxContext {
             && !file_system_policy.has_full_disk_write_access()
     }
 
+    /// Borrows the executor-owned paths needed to interpret filesystem policy entries.
+    ///
+    /// Returns `None` after the cwd has been omitted from a transport context.
+    pub fn policy_context(&self) -> Option<FileSystemSandboxPolicyContext<'_>> {
+        Some(FileSystemSandboxPolicyContext {
+            cwd: self.cwd.as_ref()?,
+            workspace_roots: &self.workspace_roots,
+            temporary_directories: self.temporary_directories.as_deref(),
+        })
+    }
+
     pub fn has_cwd_dependent_permissions(&self) -> bool {
         match &self.permissions {
             ExecPermissionProfile::Managed {
diff --git a/codex-rs/protocol/src/permissions.rs b/codex-rs/protocol/src/permissions.rs
index 1537230e0a..e94ed5c60b 100644
--- a/codex-rs/protocol/src/permissions.rs
+++ b/codex-rs/protocol/src/permissions.rs
@@ -266,6 +266,17 @@ pub struct RawFileSystemSandboxPolicy {
     pub entries: Vec<RawFileSystemSandboxEntry>,
 }
 
+/// Executor-owned paths needed to interpret filesystem sandbox policy entries.
+///
+/// Orchestrator callers keep these as `PathUri` values until execution crosses
+/// into the executor that owns them.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct FileSystemSandboxPolicyContext<'a> {
+    pub cwd: &'a PathUri,
+    pub workspace_roots: &'a [PathUri],
+    pub temporary_directories: Option<&'a [PathUri]>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct ResolvedFileSystemEntry {
     path: AbsolutePathBuf,