diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 961d0927d1..22bbdc07c7 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -504,6 +504,7 @@ dependencies = [
  "mime_guess",
  "openssl-sys",
  "patch",
+ "path-absolutize",
  "predicates",
  "rand",
  "reqwest",
diff --git a/codex-rs/cli/src/main.rs b/codex-rs/cli/src/main.rs
index fa0a14e6cb..ba6b15d99f 100644
--- a/codex-rs/cli/src/main.rs
+++ b/codex-rs/cli/src/main.rs
@@ -3,11 +3,9 @@ mod landlock;
 mod proto;
 mod seatbelt;
 
-use std::path::PathBuf;
-
-use clap::ArgAction;
 use clap::Parser;
 use codex_core::protocol::SandboxPolicy;
+use codex_core::SandboxPermissionOption;
 use codex_exec::Cli as ExecCli;
 use codex_repl::Cli as ReplCli;
 use codex_tui::Cli as TuiCli;
@@ -67,14 +65,13 @@ enum DebugCommand {
 
 #[derive(Debug, Parser)]
 struct SeatbeltCommand {
-    /// Writable folder for sandbox (can be specified multiple times).
-    #[arg(long = "writable-root", short = 'w', value_name = "DIR", action = ArgAction::Append, use_value_delimiter = false)]
-    writable_roots: Vec<PathBuf>,
-
     /// Convenience alias for low-friction sandboxed automatic execution (network-disabled sandbox that can write to cwd and TMPDIR)
     #[arg(long = "full-auto", default_value_t = false)]
     full_auto: bool,
 
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
     /// Full command args to run under seatbelt.
     #[arg(trailing_var_arg = true)]
     command: Vec<String>,
@@ -82,14 +79,13 @@ struct SeatbeltCommand {
 
 #[derive(Debug, Parser)]
 struct LandlockCommand {
-    /// Writable folder for sandbox (can be specified multiple times).
-    #[arg(long = "writable-root", short = 'w', value_name = "DIR", action = ArgAction::Append, use_value_delimiter = false)]
-    writable_roots: Vec<PathBuf>,
-
     /// Convenience alias for low-friction sandboxed automatic execution (network-disabled sandbox that can write to cwd and TMPDIR)
     #[arg(long = "full-auto", default_value_t = false)]
     full_auto: bool,
 
+    #[clap(flatten)]
+    sandbox: SandboxPermissionOption,
+
     /// Full command args to run under landlock.
     #[arg(trailing_var_arg = true)]
     command: Vec<String>,
@@ -118,19 +114,19 @@ async fn main() -> anyhow::Result<()> {
         Some(Subcommand::Debug(debug_args)) => match debug_args.cmd {
             DebugCommand::Seatbelt(SeatbeltCommand {
                 command,
-                writable_roots,
+                sandbox,
                 full_auto,
             }) => {
-                let sandbox_policy = create_sandbox_policy(full_auto, &writable_roots);
+                let sandbox_policy = create_sandbox_policy(full_auto, sandbox);
                 seatbelt::run_seatbelt(command, sandbox_policy).await?;
             }
             #[cfg(target_os = "linux")]
             DebugCommand::Landlock(LandlockCommand {
                 command,
-                writable_roots,
+                sandbox,
                 full_auto,
             }) => {
-                let sandbox_policy = create_sandbox_policy(full_auto, &writable_roots);
+                let sandbox_policy = create_sandbox_policy(full_auto, sandbox);
                 landlock::run_landlock(command, sandbox_policy)?;
             }
             #[cfg(not(target_os = "linux"))]
@@ -143,10 +139,13 @@ async fn main() -> anyhow::Result<()> {
     Ok(())
 }
 
-fn create_sandbox_policy(full_auto: bool, writable_roots: &[PathBuf]) -> SandboxPolicy {
+fn create_sandbox_policy(full_auto: bool, sandbox: SandboxPermissionOption) -> SandboxPolicy {
     if full_auto {
-        SandboxPolicy::new_full_auto_policy_with_writable_roots(writable_roots)
+        SandboxPolicy::new_full_auto_policy()
     } else {
-        SandboxPolicy::new_read_only_policy_with_writable_roots(writable_roots)
+        match sandbox.permissions.map(Into::into) {
+            Some(sandbox_policy) => sandbox_policy,
+            None => SandboxPolicy::new_read_only_policy(),
+        }
     }
 }
diff --git a/codex-rs/core/Cargo.toml b/codex-rs/core/Cargo.toml
index daadec7294..0ed550f9a8 100644
--- a/codex-rs/core/Cargo.toml
+++ b/codex-rs/core/Cargo.toml
@@ -21,6 +21,7 @@ fs-err = "3.1.0"
 futures = "0.3"
 mime_guess = "2.0"
 patch = "0.7"
+path-absolutize = "3.1.1"
 rand = "0.9"
 reqwest = { version = "0.12", features = ["json", "stream"] }
 serde = { version = "1", features = ["derive"] }
diff --git a/codex-rs/core/src/approval_mode_cli_arg.rs b/codex-rs/core/src/approval_mode_cli_arg.rs
index 8154e49fe9..f4e64febae 100644
--- a/codex-rs/core/src/approval_mode_cli_arg.rs
+++ b/codex-rs/core/src/approval_mode_cli_arg.rs
@@ -1,9 +1,14 @@
 //! Standard type to use with the `--approval-mode` CLI option.
 //! Available when the `cli` feature is enabled for the crate.
 
+use std::path::PathBuf;
+
+use clap::ArgAction;
+use clap::Parser;
 use clap::ValueEnum;
 
 use crate::protocol::AskForApproval;
+use crate::protocol::SandboxPermission;
 
 #[derive(Clone, Copy, Debug, ValueEnum)]
 #[value(rename_all = "kebab-case")]
@@ -32,3 +37,84 @@ impl From<ApprovalModeCliArg> for AskForApproval {
         }
     }
 }
+
+#[derive(Parser, Debug)]
+pub struct SandboxPermissionOption {
+    /// Specify this flag multiple times to specify the full set of permissions
+    /// to grant to Codex.
+    ///
+    /// ```shell
+    /// codex -s disk-full-read-access \
+    ///       -s disk-write-cwd \
+    ///       -s disk-write-platform-user-temp-folder \
+    ///       -s disk-write-platform-global-temp-folder
+    /// ```
+    ///
+    /// Note disk-write-folder takes a value:
+    ///
+    /// ```shell
+    ///     -s disk-write-folder=$HOME/.pyenv/shims
+    /// ```
+    ///
+    /// These permissions are quite broad and should be used with caution:
+    ///
+    /// ```shell
+    ///     -s disk-full-write-access
+    ///     -s network-full-access
+    /// ```
+    #[arg(long = "sandbox-permission", short = 's', action = ArgAction::Append, value_parser = parse_sandbox_permission)]
+    pub permissions: Option<Vec<SandboxPermission>>,
+}
+
+/// Custom value-parser so we can keep the CLI surface small *and*
+/// still handle the parameterised `disk-write-folder` case.
+fn parse_sandbox_permission(raw: &str) -> std::io::Result<SandboxPermission> {
+    let base_path = std::env::current_dir()?;
+    parse_sandbox_permission_with_base_path(raw, base_path)
+}
+
+pub(crate) fn parse_sandbox_permission_with_base_path(
+    raw: &str,
+    base_path: PathBuf,
+) -> std::io::Result<SandboxPermission> {
+    use SandboxPermission::*;
+
+    if let Some(path) = raw.strip_prefix("disk-write-folder=") {
+        return if path.is_empty() {
+            Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                "--sandbox-permission disk-write-folder=<PATH> requires a non-empty PATH",
+            ))
+        } else {
+            use path_absolutize::*;
+
+            let file = PathBuf::from(path);
+            let absolute_path = if file.is_relative() {
+                file.absolutize_from(base_path)
+            } else {
+                file.absolutize()
+            }
+            .map(|path| path.into_owned())?;
+            Ok(DiskWriteFolder {
+                folder: absolute_path,
+            })
+        };
+    }
+
+    match raw {
+        "disk-full-read-access" => Ok(DiskFullReadAccess),
+        "disk-write-platform-user-temp-folder" => Ok(DiskWritePlatformUserTempFolder),
+        "disk-write-platform-global-temp-folder" => Ok(DiskWritePlatformGlobalTempFolder),
+        "disk-write-cwd" => Ok(DiskWriteCwd),
+        "disk-full-write-access" => Ok(DiskFullWriteAccess),
+        "network-full-access" => Ok(NetworkFullAccess),
+        _ => Err(
+            std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                format!(
+                    "`{raw}` is not a recognised permission.\nRun with `--help` to see the accepted values."
+                ),
+            )
+        ),
+    }
+}
diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 55efe5a94c..c9bfa138be 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -1,3 +1,4 @@
+use crate::approval_mode_cli_arg::parse_sandbox_permission_with_base_path;
 use crate::flags::OPENAI_DEFAULT_MODEL;
 use crate::protocol::AskForApproval;
 use crate::protocol::SandboxPermission;
@@ -40,6 +41,10 @@ pub struct ConfigToml {
     /// Default approval policy for executing commands.
     pub approval_policy: Option<AskForApproval>,
 
+    // The `default` attribute ensures that the field is treated as `None` when
+    // the key is omitted from the TOML. Without it, Serde treats the field as
+    // required because we supply a custom deserializer.
+    #[serde(default, deserialize_with = "deserialize_sandbox_permissions")]
     pub sandbox_permissions: Option<Vec<SandboxPermission>>,
 
     /// Disable server-side response storage (sends the full conversation
@@ -74,6 +79,32 @@ impl ConfigToml {
     }
 }
 
+fn deserialize_sandbox_permissions<'de, D>(
+    deserializer: D,
+) -> Result<Option<Vec<SandboxPermission>>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let permissions: Option<Vec<String>> = Option::deserialize(deserializer)?;
+
+    match permissions {
+        Some(raw_permissions) => {
+            let base_path = codex_dir().map_err(serde::de::Error::custom)?;
+
+            let converted = raw_permissions
+                .into_iter()
+                .map(|raw| {
+                    parse_sandbox_permission_with_base_path(&raw, base_path.clone())
+                        .map_err(serde::de::Error::custom)
+                })
+                .collect::<Result<Vec<_>, D::Error>>()?;
+
+            Ok(Some(converted))
+        }
+        None => Ok(None),
+    }
+}
+
 /// Optional overrides for user configuration (e.g., from CLI flags).
 #[derive(Default, Debug, Clone)]
 pub struct ConfigOverrides {
@@ -174,3 +205,60 @@ pub fn log_dir() -> std::io::Result<PathBuf> {
     p.push("log");
     Ok(p)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Verify that the `sandbox_permissions` field on `ConfigToml` correctly
+    /// differentiates between a value that is completely absent in the
+    /// provided TOML (i.e. `None`) and one that is explicitly specified as an
+    /// empty array (i.e. `Some(vec![])`). This ensures that downstream logic
+    /// that treats these two cases differently (default read-only policy vs a
+    /// fully locked-down sandbox) continues to function.
+    #[test]
+    fn test_sandbox_permissions_none_vs_empty_vec() {
+        // Case 1: `sandbox_permissions` key is *absent* from the TOML source.
+        let toml_source_without_key = "";
+        let cfg_without_key: ConfigToml = toml::from_str(toml_source_without_key)
+            .expect("TOML deserialization without key should succeed");
+        assert!(cfg_without_key.sandbox_permissions.is_none());
+
+        // Case 2: `sandbox_permissions` is present but set to an *empty array*.
+        let toml_source_with_empty = "sandbox_permissions = []";
+        let cfg_with_empty: ConfigToml = toml::from_str(toml_source_with_empty)
+            .expect("TOML deserialization with empty array should succeed");
+        assert_eq!(Some(vec![]), cfg_with_empty.sandbox_permissions);
+
+        // Case 3: `sandbox_permissions` contains a non-empty list of valid values.
+        let toml_source_with_values = r#"
+            sandbox_permissions = ["disk-full-read-access", "network-full-access"]
+        "#;
+        let cfg_with_values: ConfigToml = toml::from_str(toml_source_with_values)
+            .expect("TOML deserialization with valid permissions should succeed");
+
+        assert_eq!(
+            Some(vec![
+                SandboxPermission::DiskFullReadAccess,
+                SandboxPermission::NetworkFullAccess
+            ]),
+            cfg_with_values.sandbox_permissions
+        );
+    }
+
+    /// Deserializing a TOML string containing an *invalid* permission should
+    /// fail with a helpful error rather than silently defaulting or
+    /// succeeding.
+    #[test]
+    fn test_sandbox_permissions_illegal_value() {
+        let toml_bad = r#"sandbox_permissions = ["not-a-real-permission"]"#;
+
+        let err = toml::from_str::<ConfigToml>(toml_bad)
+            .expect_err("Deserialization should fail for invalid permission");
+
+        // Make sure the error message contains the invalid value so users have
+        // useful feedback.
+        let msg = err.to_string();
+        assert!(msg.contains("not-a-real-permission"));
+    }
+}
diff --git a/codex-rs/core/src/lib.rs b/codex-rs/core/src/lib.rs
index 389694a38b..b1c746beb2 100644
--- a/codex-rs/core/src/lib.rs
+++ b/codex-rs/core/src/lib.rs
@@ -27,3 +27,5 @@ pub use codex::Codex;
 mod approval_mode_cli_arg;
 #[cfg(feature = "cli")]
 pub use approval_mode_cli_arg::ApprovalModeCliArg;
+#[cfg(feature = "cli")]
+pub use approval_mode_cli_arg::SandboxPermissionOption;
diff --git a/codex-rs/core/src/protocol.rs b/codex-rs/core/src/protocol.rs
index 23c6e307bb..5c2d35c159 100644
--- a/codex-rs/core/src/protocol.rs
+++ b/codex-rs/core/src/protocol.rs
@@ -132,16 +132,6 @@ impl SandboxPolicy {
         }
     }
 
-    pub fn new_full_auto_policy_with_writable_roots(writable_roots: &[PathBuf]) -> Self {
-        let mut permissions = Self::new_full_auto_policy().permissions;
-        permissions.extend(writable_roots.iter().map(|folder| {
-            SandboxPermission::DiskWriteFolder {
-                folder: folder.clone(),
-            }
-        }));
-        Self { permissions }
-    }
-
     pub fn has_full_disk_read_access(&self) -> bool {
         self.permissions
             .iter()
diff --git a/codex-rs/exec/src/cli.rs b/codex-rs/exec/src/cli.rs
index cd014e71f2..1b32b52206 100644
--- a/codex-rs/exec/src/cli.rs
+++ b/codex-rs/exec/src/cli.rs
@@ -1,5 +1,6 @@
 use clap::Parser;
 use clap::ValueEnum;
+use codex_core::SandboxPermissionOption;
 use std::path::PathBuf;
 
 #[derive(Parser, Debug)]
@@ -17,6 +18,9 @@ pub struct Cli {
     #[arg(long = "full-auto", default_value_t = false)]
     pub full_auto: bool,
 
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
     /// Allow running Codex outside a Git repository.
     #[arg(long = "skip-git-repo-check", default_value_t = false)]
     pub skip_git_repo_check: bool,
diff --git a/codex-rs/exec/src/lib.rs b/codex-rs/exec/src/lib.rs
index 9d5b95316a..1541102e32 100644
--- a/codex-rs/exec/src/lib.rs
+++ b/codex-rs/exec/src/lib.rs
@@ -28,6 +28,7 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
         images,
         model,
         full_auto,
+        sandbox,
         skip_git_repo_check,
         disable_response_storage,
         color,
@@ -65,7 +66,7 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
     let sandbox_policy = if full_auto {
         Some(SandboxPolicy::new_full_auto_policy())
     } else {
-        None
+        sandbox.permissions.clone().map(Into::into)
     };
 
     // Load configuration and determine approval policy
diff --git a/codex-rs/repl/src/cli.rs b/codex-rs/repl/src/cli.rs
index 567a8ea491..c9fa1ee9ae 100644
--- a/codex-rs/repl/src/cli.rs
+++ b/codex-rs/repl/src/cli.rs
@@ -1,6 +1,7 @@
 use clap::ArgAction;
 use clap::Parser;
 use codex_core::ApprovalModeCliArg;
+use codex_core::SandboxPermissionOption;
 use std::path::PathBuf;
 
 /// Command‑line arguments.
@@ -40,6 +41,9 @@ pub struct Cli {
     #[arg(long = "full-auto", default_value_t = false)]
     pub full_auto: bool,
 
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
     /// Allow running Codex outside a Git repository.  By default the CLI
     /// aborts early when the current working directory is **not** inside a
     /// Git repo because most agents rely on `git` for interacting with the
diff --git a/codex-rs/repl/src/lib.rs b/codex-rs/repl/src/lib.rs
index d4bfbc2f95..fea756b773 100644
--- a/codex-rs/repl/src/lib.rs
+++ b/codex-rs/repl/src/lib.rs
@@ -84,7 +84,8 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
             Some(AskForApproval::OnFailure),
         )
     } else {
-        (None, cli.approval_policy.map(Into::into))
+        let sandbox_policy = cli.sandbox.permissions.clone().map(Into::into);
+        (sandbox_policy, cli.approval_policy.map(Into::into))
     };
 
     // Load config file and apply CLI overrides (model & approval policy)
diff --git a/codex-rs/tui/src/cli.rs b/codex-rs/tui/src/cli.rs
index 1c00ae0862..43a1f5b165 100644
--- a/codex-rs/tui/src/cli.rs
+++ b/codex-rs/tui/src/cli.rs
@@ -1,5 +1,6 @@
 use clap::Parser;
 use codex_core::ApprovalModeCliArg;
+use codex_core::SandboxPermissionOption;
 use std::path::PathBuf;
 
 #[derive(Parser, Debug)]
@@ -24,6 +25,9 @@ pub struct Cli {
     #[arg(long = "full-auto", default_value_t = false)]
     pub full_auto: bool,
 
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
     /// Allow running Codex outside a Git repository.
     #[arg(long = "skip-git-repo-check", default_value_t = false)]
     pub skip_git_repo_check: bool,
diff --git a/codex-rs/tui/src/lib.rs b/codex-rs/tui/src/lib.rs
index db43bde6f1..e23b8c6902 100644
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -41,7 +41,8 @@ pub fn run_main(cli: Cli) -> std::io::Result<()> {
             Some(AskForApproval::OnFailure),
         )
     } else {
-        (None, cli.approval_policy.map(Into::into))
+        let sandbox_policy = cli.sandbox.permissions.clone().map(Into::into);
+        (sandbox_policy, cli.approval_policy.map(Into::into))
     };
 
     let config = {