refactor: prepare unified exec for zsh-fork backend

codex-rs/Cargo.toml

@@ -70,7 +70,7 @@ members = [
 resolver = "2"
 
 [workspace.package]
-version = "0.108.0-alpha.9"
+version = "0.0.0"
 # Track the edition for all workspace crates in one place. Individual
 # crates can still override this value, but keeping it here means new
 # crates created with `cargo new -w ...` automatically inherit the 2024

codex-rs/core/src/tools/runtimes/shell.rs

@@ -5,7 +5,7 @@ Executes shell requests under the orchestrator: asks for approval when needed,
 builds a CommandSpec, and runs it under the current SandboxAttempt.
 */
 #[cfg(unix)]
-mod unix_escalation;
+pub(crate) mod unix_escalation;
 
 use crate::command_canonicalization::canonicalize_command_for_approval;
 use crate::exec::ExecToolCallOutput;

codex-rs/core/src/tools/runtimes/shell/unix_escalation.rs

@@ -6,6 +6,7 @@ use crate::exec::ExecToolCallOutput;
 use crate::exec::SandboxType;
 use crate::exec::is_likely_sandbox_denied;
 use crate::features::Feature;
+use crate::sandboxing::ExecRequest;
 use crate::sandboxing::SandboxPermissions;
 use crate::shell::ShellType;
 use crate::skills::SkillMetadata;
@@ -36,6 +37,7 @@ use codex_shell_escalation::EscalationDecision;
 use codex_shell_escalation::EscalationExecution;
 use codex_shell_escalation::EscalationPermissions;
 use codex_shell_escalation::EscalationPolicy;
+use codex_shell_escalation::EscalationSession;
 use codex_shell_escalation::ExecParams;
 use codex_shell_escalation::ExecResult;
 use codex_shell_escalation::Permissions as EscalatedPermissions;
@@ -51,6 +53,11 @@ use tokio::sync::RwLock;
 use tokio_util::sync::CancellationToken;
 use uuid::Uuid;
 
+pub(crate) struct PreparedUnifiedExecZshFork {
+    pub(crate) exec_request: ExecRequest,
+    pub(crate) escalation_session: EscalationSession,
+}
+
 pub(super) async fn try_run_zsh_fork(
     req: &ShellRequest,
     attempt: &SandboxAttempt<'_>,
@@ -95,7 +102,7 @@ pub(super) async fn try_run_zsh_fork(
         justification,
         arg0,
     } = sandbox_exec_request;
-    let ParsedShellCommand { script, login } = extract_shell_script(&command)?;
+    let ParsedShellCommand { script, login, .. } = extract_shell_script(&command)?;
     let effective_timeout = Duration::from_millis(
         req.timeout_ms
             .unwrap_or(crate::exec::DEFAULT_EXEC_COMMAND_TIMEOUT_MS),
@@ -172,6 +179,103 @@ pub(super) async fn try_run_zsh_fork(
     map_exec_result(attempt.sandbox, exec_result).map(Some)
 }
 
+pub(crate) async fn prepare_unified_exec_zsh_fork(
+    req: &crate::tools::runtimes::unified_exec::UnifiedExecRequest,
+    attempt: &SandboxAttempt<'_>,
+    ctx: &ToolCtx,
+    exec_request: ExecRequest,
+) -> Result<Option<PreparedUnifiedExecZshFork>, ToolError> {
+    let Some(shell_zsh_path) = ctx.session.services.shell_zsh_path.as_ref() else {
+        tracing::warn!("ZshFork backend specified, but shell_zsh_path is not configured.");
+        return Ok(None);
+    };
+    if !ctx.session.features().enabled(Feature::ShellZshFork) {
+        tracing::warn!("ZshFork backend specified, but ShellZshFork feature is not enabled.");
+        return Ok(None);
+    }
+    if !matches!(ctx.session.user_shell().shell_type, ShellType::Zsh) {
+        tracing::warn!("ZshFork backend specified, but user shell is not Zsh.");
+        return Ok(None);
+    }
+
+    let parsed = match extract_shell_script(&exec_request.command) {
+        Ok(parsed) => parsed,
+        Err(err) => {
+            tracing::warn!("ZshFork unified exec fallback: {err:?}");
+            return Ok(None);
+        }
+    };
+    if parsed.program != shell_zsh_path.to_string_lossy() {
+        tracing::warn!(
+            "ZshFork backend specified, but unified exec command targets `{}` instead of `{}`.",
+            parsed.program,
+            shell_zsh_path.display(),
+        );
+        return Ok(None);
+    }
+
+    let exec_policy = Arc::new(RwLock::new(
+        ctx.session.services.exec_policy.current().as_ref().clone(),
+    ));
+    let command_executor = CoreShellCommandExecutor {
+        command: exec_request.command.clone(),
+        cwd: exec_request.cwd.clone(),
+        sandbox_policy: exec_request.sandbox_policy.clone(),
+        sandbox: exec_request.sandbox,
+        env: exec_request.env.clone(),
+        network: exec_request.network.clone(),
+        windows_sandbox_level: exec_request.windows_sandbox_level,
+        sandbox_permissions: exec_request.sandbox_permissions,
+        justification: exec_request.justification.clone(),
+        arg0: exec_request.arg0.clone(),
+        sandbox_policy_cwd: ctx.turn.cwd.clone(),
+        macos_seatbelt_profile_extensions: ctx
+            .turn
+            .config
+            .permissions
+            .macos_seatbelt_profile_extensions
+            .clone(),
+        codex_linux_sandbox_exe: ctx.turn.codex_linux_sandbox_exe.clone(),
+        use_linux_sandbox_bwrap: ctx.turn.features.enabled(Feature::UseLinuxSandboxBwrap),
+    };
+    let main_execve_wrapper_exe = ctx
+        .session
+        .services
+        .main_execve_wrapper_exe
+        .clone()
+        .ok_or_else(|| {
+            ToolError::Rejected(
+                "zsh fork feature enabled, but execve wrapper is not configured".to_string(),
+            )
+        })?;
+    let escalation_policy = CoreShellActionProvider {
+        policy: Arc::clone(&exec_policy),
+        session: Arc::clone(&ctx.session),
+        turn: Arc::clone(&ctx.turn),
+        call_id: ctx.call_id.clone(),
+        approval_policy: ctx.turn.approval_policy.value(),
+        sandbox_policy: attempt.policy.clone(),
+        sandbox_permissions: req.sandbox_permissions,
+        prompt_permissions: req.additional_permissions.clone(),
+        stopwatch: Stopwatch::unlimited(),
+    };
+
+    let escalate_server = EscalateServer::new(
+        shell_zsh_path.clone(),
+        main_execve_wrapper_exe,
+        escalation_policy,
+    );
+    let escalation_session = escalate_server
+        .start_session(Arc::new(command_executor))
+        .map_err(|err| ToolError::Rejected(err.to_string()))?;
+    let mut exec_request = exec_request;
+    exec_request.env.extend(escalation_session.env().clone());
+    Ok(Some(PreparedUnifiedExecZshFork {
+        exec_request,
+        escalation_session,
+    }))
+}
+
 struct CoreShellActionProvider {
     policy: Arc<RwLock<Policy>>,
     session: Arc<crate::codex::Session>,
@@ -809,6 +913,7 @@ impl CoreShellCommandExecutor {
 
 #[derive(Debug, Eq, PartialEq)]
 struct ParsedShellCommand {
+    program: String,
     script: String,
     login: bool,
 }
@@ -817,12 +922,20 @@ fn extract_shell_script(command: &[String]) -> Result<ParsedShellCommand, ToolEr
     // Commands reaching zsh-fork can be wrapped by environment/sandbox helpers, so
     // we search for the first `-c`/`-lc` triple anywhere in the argv rather
     // than assuming it is the first positional form.
-    if let Some((script, login)) = command.windows(3).find_map(|parts| match parts {
-        [_, flag, script] if flag == "-c" => Some((script.to_owned(), false)),
-        [_, flag, script] if flag == "-lc" => Some((script.to_owned(), true)),
+    if let Some((program, script, login)) = command.windows(3).find_map(|parts| match parts {
+        [program, flag, script] if flag == "-c" => {
+            Some((program.to_owned(), script.to_owned(), false))
+        }
+        [program, flag, script] if flag == "-lc" => {
+            Some((program.to_owned(), script.to_owned(), true))
+        }
         _ => None,
     }) {
-        return Ok(ParsedShellCommand { script, login });
+        return Ok(ParsedShellCommand {
+            program,
+            script,
+            login,
+        });
     }
 
     Err(ToolError::Rejected(

codex-rs/core/src/tools/runtimes/shell/unix_escalation_tests.rs

@@ -64,6 +64,7 @@ fn extract_shell_script_preserves_login_flag() {
     assert_eq!(
         extract_shell_script(&["/bin/zsh".into(), "-lc".into(), "echo hi".into()]).unwrap(),
         ParsedShellCommand {
+            program: "/bin/zsh".to_string(),
             script: "echo hi".to_string(),
             login: true,
         }
@@ -71,6 +72,7 @@ fn extract_shell_script_preserves_login_flag() {
     assert_eq!(
         extract_shell_script(&["/bin/zsh".into(), "-c".into(), "echo hi".into()]).unwrap(),
         ParsedShellCommand {
+            program: "/bin/zsh".to_string(),
             script: "echo hi".to_string(),
             login: false,
         }
@@ -89,6 +91,7 @@ fn extract_shell_script_supports_wrapped_command_prefixes() {
         ])
         .unwrap(),
         ParsedShellCommand {
+            program: "/bin/zsh".to_string(),
             script: "echo hello".to_string(),
             login: true,
         }
@@ -105,6 +108,7 @@ fn extract_shell_script_supports_wrapped_command_prefixes() {
         ])
         .unwrap(),
         ParsedShellCommand {
+            program: "/bin/zsh".to_string(),
             script: "pwd".to_string(),
             login: false,
         }

codex-rs/core/src/tools/runtimes/unified_exec.rs

@@ -16,6 +16,8 @@ use crate::tools::network_approval::NetworkApprovalMode;
 use crate::tools::network_approval::NetworkApprovalSpec;
 use crate::tools::runtimes::build_command_spec;
 use crate::tools::runtimes::maybe_wrap_shell_lc_with_snapshot;
+#[cfg(unix)]
+use crate::tools::runtimes::shell::unix_escalation;
 use crate::tools::sandboxing::Approvable;
 use crate::tools::sandboxing::ApprovalCtx;
 use crate::tools::sandboxing::ExecApprovalRequirement;
@@ -28,6 +30,7 @@ use crate::tools::sandboxing::ToolError;
 use crate::tools::sandboxing::ToolRuntime;
 use crate::tools::sandboxing::sandbox_override_for_first_attempt;
 use crate::tools::sandboxing::with_cached_approval;
+use crate::tools::spec::UnifiedExecBackendConfig;
 use crate::unified_exec::UnifiedExecError;
 use crate::unified_exec::UnifiedExecProcess;
 use crate::unified_exec::UnifiedExecProcessManager;
@@ -63,10 +66,18 @@ pub struct UnifiedExecApprovalKey {
 
 pub struct UnifiedExecRuntime<'a> {
     manager: &'a UnifiedExecProcessManager,
+    #[cfg(unix)]
+    backend: UnifiedExecBackendConfig,
 }
 
 impl<'a> UnifiedExecRuntime<'a> {
-    pub fn new(manager: &'a UnifiedExecProcessManager) -> Self {
+    #[cfg(unix)]
+    pub fn new(manager: &'a UnifiedExecProcessManager, backend: UnifiedExecBackendConfig) -> Self {
+        Self { manager, backend }
+    }
+
+    #[cfg(not(unix))]
+    pub fn new(manager: &'a UnifiedExecProcessManager, _backend: UnifiedExecBackendConfig) -> Self {
         Self { manager }
     }
 }
@@ -184,6 +195,54 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
         if let Some(network) = req.network.as_ref() {
             network.apply_to_env(&mut env);
         }
+        #[cfg(unix)]
+        if self.backend == UnifiedExecBackendConfig::ZshFork {
+            let spec = build_command_spec(
+                &command,
+                &req.cwd,
+                &env,
+                ExecExpiration::DefaultTimeout,
+                req.sandbox_permissions,
+                req.additional_permissions.clone(),
+                req.justification.clone(),
+            )
+            .map_err(|_| ToolError::Rejected("missing command line for PTY".to_string()))?;
+            let exec_env = attempt
+                .env_for(spec, req.network.as_ref())
+                .map_err(|err| ToolError::Codex(err.into()))?;
+            match unix_escalation::prepare_unified_exec_zsh_fork(req, attempt, ctx, exec_env)
+                .await?
+            {
+                Some(prepared) => {
+                    let unix_escalation::PreparedUnifiedExecZshFork {
+                        exec_request,
+                        escalation_session,
+                    } = prepared;
+                    return self
+                        .manager
+                        .open_session_with_exec_env(
+                            &exec_request,
+                            req.tty,
+                            Some(escalation_session),
+                        )
+                        .await
+                        .map_err(|err| match err {
+                            UnifiedExecError::SandboxDenied { output, .. } => {
+                                ToolError::Codex(CodexErr::Sandbox(SandboxErr::Denied {
+                                    output: Box::new(output),
+                                    network_policy_decision: None,
+                                }))
+                            }
+                            other => ToolError::Rejected(other.to_string()),
+                        });
+                }
+                None => {
+                    tracing::warn!(
+                        "UnifiedExec ZshFork backend specified, but conditions for using it were not met, falling back to direct execution",
+                    );
+                }
+            }
+        }
         let spec = build_command_spec(
             &command,
             &req.cwd,
@@ -198,7 +257,7 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
             .env_for(spec, req.network.as_ref())
             .map_err(|err| ToolError::Codex(err.into()))?;
         self.manager
-            .open_session_with_exec_env(&exec_env, req.tty)
+            .open_session_with_exec_env(&exec_env, req.tty, None)
             .await
             .map_err(|err| match err {
                 UnifiedExecError::SandboxDenied { output, .. } => {

codex-rs/core/src/tools/spec.rs

@@ -42,10 +42,17 @@ pub enum ShellCommandBackendConfig {
     ZshFork,
 }
 
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+pub enum UnifiedExecBackendConfig {
+    Direct,
+    ZshFork,
+}
+
 #[derive(Debug, Clone)]
 pub(crate) struct ToolsConfig {
     pub shell_type: ConfigShellToolType,
     shell_command_backend: ShellCommandBackendConfig,
+    pub unified_exec_backend: UnifiedExecBackendConfig,
     pub allow_login_shell: bool,
     pub apply_patch_tool_type: Option<ApplyPatchToolType>,
     pub web_search_mode: Option<WebSearchMode>,
@@ -94,6 +101,12 @@ impl ToolsConfig {
             } else {
                 ShellCommandBackendConfig::Classic
             };
+        let unified_exec_backend =
+            if features.enabled(Feature::ShellTool) && features.enabled(Feature::ShellZshFork) {
+                UnifiedExecBackendConfig::ZshFork
+            } else {
+                UnifiedExecBackendConfig::Direct
+            };
 
         let shell_type = if !features.enabled(Feature::ShellTool) {
             ConfigShellToolType::Disabled
@@ -132,6 +145,7 @@ impl ToolsConfig {
         Self {
             shell_type,
             shell_command_backend,
+            unified_exec_backend,
             allow_login_shell: true,
             apply_patch_tool_type,
             web_search_mode: *web_search_mode,
@@ -2727,6 +2741,10 @@ mod tests {
             tools_config.shell_command_backend,
             ShellCommandBackendConfig::ZshFork
         );
+        assert_eq!(
+            tools_config.unified_exec_backend,
+            UnifiedExecBackendConfig::ZshFork
+        );
     }
 
     #[test]

codex-rs/core/src/unified_exec/process.rs

@@ -24,6 +24,12 @@ use super::UNIFIED_EXEC_OUTPUT_MAX_TOKENS;
 use super::UnifiedExecError;
 use super::head_tail_buffer::HeadTailBuffer;
 
+#[cfg(unix)]
+pub(crate) use codex_shell_escalation::EscalationSession;
+#[cfg(not(unix))]
+#[derive(Debug)]
+pub(crate) struct EscalationSession;
+
 pub(crate) type OutputBuffer = Arc<Mutex<HeadTailBuffer>>;
 pub(crate) struct OutputHandles {
     pub(crate) output_buffer: OutputBuffer,
@@ -44,6 +50,7 @@ pub(crate) struct UnifiedExecProcess {
     output_drained: Arc<Notify>,
     output_task: JoinHandle<()>,
     sandbox_type: SandboxType,
+    _escalation_session: Option<EscalationSession>,
 }
 
 impl UnifiedExecProcess {
@@ -51,6 +58,7 @@ impl UnifiedExecProcess {
         process_handle: ExecCommandSession,
         initial_output_rx: tokio::sync::broadcast::Receiver<Vec<u8>>,
         sandbox_type: SandboxType,
+        escalation_session: Option<EscalationSession>,
     ) -> Self {
         let output_buffer = Arc::new(Mutex::new(HeadTailBuffer::default()));
         let output_notify = Arc::new(Notify::new());
@@ -92,6 +100,7 @@ impl UnifiedExecProcess {
             output_drained,
             output_task,
             sandbox_type,
+            _escalation_session: escalation_session,
         }
     }
 
@@ -196,13 +205,14 @@ impl UnifiedExecProcess {
     pub(super) async fn from_spawned(
         spawned: SpawnedPty,
         sandbox_type: SandboxType,
+        escalation_session: Option<EscalationSession>,
     ) -> Result<Self, UnifiedExecError> {
         let SpawnedPty {
             session: process_handle,
             output_rx,
             mut exit_rx,
         } = spawned;
-        let managed = Self::new(process_handle, output_rx, sandbox_type);
+        let managed = Self::new(process_handle, output_rx, sandbox_type, escalation_session);
 
         let exit_ready = matches!(exit_rx.try_recv(), Ok(_) | Err(TryRecvError::Closed));
 

codex-rs/core/src/unified_exec/process_manager.rs

@@ -47,6 +47,7 @@ use crate::unified_exec::async_watcher::start_streaming_output;
 use crate::unified_exec::clamp_yield_time;
 use crate::unified_exec::generate_chunk_id;
 use crate::unified_exec::head_tail_buffer::HeadTailBuffer;
+use crate::unified_exec::process::EscalationSession;
 use crate::unified_exec::process::OutputBuffer;
 use crate::unified_exec::process::OutputHandles;
 use crate::unified_exec::process::UnifiedExecProcess;
@@ -528,6 +529,7 @@ impl UnifiedExecProcessManager {
         &self,
         env: &ExecRequest,
         tty: bool,
+        escalation_session: Option<EscalationSession>,
     ) -> Result<UnifiedExecProcess, UnifiedExecError> {
         let (program, args) = env
             .command
@@ -555,7 +557,15 @@ impl UnifiedExecProcessManager {
         };
         let spawned =
             spawn_result.map_err(|err| UnifiedExecError::create_process(err.to_string()))?;
-        UnifiedExecProcess::from_spawned(spawned, env.sandbox).await
+        #[cfg(unix)]
+        let escalation_session = {
+            let mut escalation_session = escalation_session;
+            if let Some(session) = escalation_session.as_mut() {
+                session.close_client_socket();
+            }
+            escalation_session
+        };
+        UnifiedExecProcess::from_spawned(spawned, env.sandbox, escalation_session).await
     }
 
     pub(super) async fn open_session_with_sandbox(
@@ -569,7 +579,8 @@ impl UnifiedExecProcessManager {
             Some(context.session.conversation_id),
         ));
         let mut orchestrator = ToolOrchestrator::new();
-        let mut runtime = UnifiedExecRuntime::new(self);
+        let mut runtime =
+            UnifiedExecRuntime::new(self, context.turn.tools_config.unified_exec_backend);
         let exec_approval_requirement = context
             .session
             .services

codex-rs/shell-escalation/src/lib.rs

@@ -14,6 +14,8 @@ pub use unix::EscalationPermissions;
 #[cfg(unix)]
 pub use unix::EscalationPolicy;
 #[cfg(unix)]
+pub use unix::EscalationSession;
+#[cfg(unix)]
 pub use unix::ExecParams;
 #[cfg(unix)]
 pub use unix::ExecResult;

codex-rs/shell-escalation/src/unix/escalate_server.rs

@@ -7,7 +7,9 @@ use std::time::Duration;
 
 use anyhow::Context as _;
 use codex_utils_absolute_path::AbsolutePathBuf;
+use socket2::Socket;
 use tokio::process::Command;
+use tokio::task::JoinHandle;
 use tokio_util::sync::CancellationToken;
 
 use crate::unix::escalate_protocol::ESCALATE_SOCKET_ENV_VAR;
@@ -82,6 +84,29 @@ pub struct PreparedExec {
     pub arg0: Option<String>,
 }
 
+#[derive(Debug)]
+pub struct EscalationSession {
+    env: HashMap<String, String>,
+    task: JoinHandle<anyhow::Result<()>>,
+    client_socket: Option<Socket>,
+}
+
+impl EscalationSession {
+    pub fn env(&self) -> &HashMap<String, String> {
+        &self.env
+    }
+
+    pub fn close_client_socket(&mut self) {
+        self.client_socket.take();
+    }
+}
+
+impl Drop for EscalationSession {
+    fn drop(&mut self) {
+        self.task.abort();
+    }
+}
+
 pub struct EscalateServer {
     bash_path: PathBuf,
     execve_wrapper: PathBuf,
@@ -106,16 +131,42 @@ impl EscalateServer {
         cancel_rx: CancellationToken,
         command_executor: Arc<dyn ShellCommandExecutor>,
     ) -> anyhow::Result<ExecResult> {
+        let session = self.start_session(Arc::clone(&command_executor))?;
+        let command = vec![
+            self.bash_path.to_string_lossy().to_string(),
+            if params.login == Some(false) {
+                "-c".to_string()
+            } else {
+                "-lc".to_string()
+            },
+            params.command,
+        ];
+        let workdir = AbsolutePathBuf::try_from(params.workdir)?;
+        let result = command_executor
+            .run(
+                command,
+                workdir.to_path_buf(),
+                session.env().clone(),
+                cancel_rx,
+            )
+            .await?;
+        Ok(result)
+    }
+
+    pub fn start_session(
+        &self,
+        command_executor: Arc<dyn ShellCommandExecutor>,
+    ) -> anyhow::Result<EscalationSession> {
         let (escalate_server, escalate_client) = AsyncDatagramSocket::pair()?;
         let client_socket = escalate_client.into_inner();
         // Only the client endpoint should cross exec into the wrapper process.
         client_socket.set_cloexec(false)?;
-        let escalate_task = tokio::spawn(escalate_task(
+        let task = tokio::spawn(escalate_task(
             escalate_server,
             Arc::clone(&self.policy),
             Arc::clone(&command_executor),
         ));
-        let mut env = std::env::vars().collect::<HashMap<String, String>>();
+        let mut env = HashMap::new();
         env.insert(
             ESCALATE_SOCKET_ENV_VAR.to_string(),
             client_socket.as_raw_fd().to_string(),
@@ -128,22 +179,11 @@ impl EscalateServer {
             LEGACY_BASH_EXEC_WRAPPER_ENV_VAR.to_string(),
             self.execve_wrapper.to_string_lossy().to_string(),
         );
-
-        let command = vec![
-            self.bash_path.to_string_lossy().to_string(),
-            if params.login == Some(false) {
-                "-c".to_string()
-            } else {
-                "-lc".to_string()
-            },
-            params.command,
-        ];
-        let workdir = AbsolutePathBuf::try_from(params.workdir)?;
-        let result = command_executor
-            .run(command, workdir.to_path_buf(), env, cancel_rx)
-            .await?;
-        escalate_task.abort();
-        Ok(result)
+        Ok(EscalationSession {
+            env,
+            task,
+            client_socket: Some(client_socket),
+        })
     }
 }
 
@@ -390,6 +430,37 @@ mod tests {
         }
     }
 
+    #[tokio::test]
+    async fn start_session_exposes_wrapper_env_overlay() -> anyhow::Result<()> {
+        let execve_wrapper = PathBuf::from("/tmp/codex-execve-wrapper");
+        let execve_wrapper_str = execve_wrapper.to_string_lossy().to_string();
+        let server = EscalateServer::new(
+            PathBuf::from("/bin/bash"),
+            execve_wrapper.clone(),
+            DeterministicEscalationPolicy {
+                decision: EscalationDecision::run(),
+            },
+        );
+
+        let mut session = server.start_session(Arc::new(ForwardingShellCommandExecutor))?;
+        let env = session.env();
+        assert_eq!(env.get(EXEC_WRAPPER_ENV_VAR), Some(&execve_wrapper_str));
+        assert_eq!(
+            env.get(LEGACY_BASH_EXEC_WRAPPER_ENV_VAR),
+            Some(&execve_wrapper_str)
+        );
+        let socket_fd = env
+            .get(ESCALATE_SOCKET_ENV_VAR)
+            .expect("session should export shell escalation socket");
+        let socket_fd = socket_fd.parse::<i32>()?;
+        assert!(socket_fd >= 0);
+        assert_ne!(unsafe { libc::fcntl(socket_fd, libc::F_GETFD) }, -1);
+        session.close_client_socket();
+        assert_eq!(unsafe { libc::fcntl(socket_fd, libc::F_GETFD) }, -1);
+
+        Ok(())
+    }
+
     #[tokio::test]
     async fn handle_escalate_session_respects_run_in_sandbox_decision() -> anyhow::Result<()> {
         let (server, client) = AsyncSocket::pair()?;

codex-rs/shell-escalation/src/unix/mod.rs

@@ -66,6 +66,7 @@ pub use self::escalate_protocol::EscalateAction;
 pub use self::escalate_protocol::EscalationDecision;
 pub use self::escalate_protocol::EscalationExecution;
 pub use self::escalate_server::EscalateServer;
+pub use self::escalate_server::EscalationSession;
 pub use self::escalate_server::ExecParams;
 pub use self::escalate_server::ExecResult;
 pub use self::escalate_server::PreparedExec;

codex-rs/shell-escalation/src/unix/stopwatch.rs

@@ -9,7 +9,7 @@ use tokio_util::sync::CancellationToken;
 
 #[derive(Clone, Debug)]
 pub struct Stopwatch {
-    limit: Duration,
+    limit: Option<Duration>,
     inner: Arc<Mutex<StopwatchState>>,
     notify: Arc<Notify>,
 }
@@ -30,13 +30,27 @@ impl Stopwatch {
                 active_pauses: 0,
             })),
             notify: Arc::new(Notify::new()),
-            limit,
+            limit: Some(limit),
+        }
+    }
+
+    pub fn unlimited() -> Self {
+        Self {
+            inner: Arc::new(Mutex::new(StopwatchState {
+                elapsed: Duration::ZERO,
+                running_since: Some(Instant::now()),
+                active_pauses: 0,
+            })),
+            notify: Arc::new(Notify::new()),
+            limit: None,
         }
     }
 
     pub fn cancellation_token(&self) -> CancellationToken {
-        let limit = self.limit;
         let token = CancellationToken::new();
+        let Some(limit) = self.limit else {
+            return token;
+        };
         let cancel = token.clone();
         let inner = Arc::clone(&self.inner);
         let notify = Arc::clone(&self.notify);
@@ -208,4 +222,16 @@ mod tests {
         // Now the stopwatch should resume and hit the limit shortly after.
         token.cancelled().await;
     }
+
+    #[tokio::test]
+    async fn unlimited_stopwatch_never_cancels() {
+        let stopwatch = Stopwatch::unlimited();
+        let token = stopwatch.cancellation_token();
+
+        assert!(
+            timeout(Duration::from_millis(30), token.cancelled())
+                .await
+                .is_err()
+        );
+    }
 }