diff --git a/codex-rs/exec/src/cli.rs b/codex-rs/exec/src/cli.rs
index 065f4826a..0b5b0b4b6 100644
--- a/codex-rs/exec/src/cli.rs
+++ b/codex-rs/exec/src/cli.rs
@@ -52,6 +52,10 @@ pub struct Cli {
     #[arg(long = "skip-git-repo-check", default_value_t = false)]
     pub skip_git_repo_check: bool,
 
+    /// Additional directories that should be writable alongside the primary workspace.
+    #[arg(long = "add-dir", value_name = "DIR", value_hint = clap::ValueHint::DirPath)]
+    pub add_dir: Vec<PathBuf>,
+
     /// Path to a JSON Schema file describing the model's final response shape.
     #[arg(long = "output-schema", value_name = "FILE")]
     pub output_schema: Option<PathBuf>,
diff --git a/codex-rs/exec/src/lib.rs b/codex-rs/exec/src/lib.rs
index 13d43f61e..a9cf6b2c6 100644
--- a/codex-rs/exec/src/lib.rs
+++ b/codex-rs/exec/src/lib.rs
@@ -62,6 +62,7 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
         dangerously_bypass_approvals_and_sandbox,
         cwd,
         skip_git_repo_check,
+        add_dir,
         color,
         last_message_file,
         json: json_mode,
@@ -180,7 +181,7 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
         show_raw_agent_reasoning: oss.then_some(true),
         tools_web_search_request: None,
         experimental_sandbox_command_assessment: None,
-        additional_writable_roots: Vec::new(),
+        additional_writable_roots: add_dir,
     };
     // Parse `-c` overrides.
     let cli_kv_overrides = match config_overrides.parse_overrides() {
diff --git a/codex-rs/exec/tests/suite/add_dir.rs b/codex-rs/exec/tests/suite/add_dir.rs
new file mode 100644
index 000000000..2093c46ac
--- /dev/null
+++ b/codex-rs/exec/tests/suite/add_dir.rs
@@ -0,0 +1,72 @@
+#![cfg(not(target_os = "windows"))]
+#![allow(clippy::expect_used, clippy::unwrap_used)]
+
+use core_test_support::responses;
+use core_test_support::test_codex_exec::test_codex_exec;
+
+/// Verify that the --add-dir flag is accepted and the command runs successfully.
+/// This test confirms the CLI argument is properly wired up.
+#[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+async fn accepts_add_dir_flag() -> anyhow::Result<()> {
+    let test = test_codex_exec();
+
+    let server = responses::start_mock_server().await;
+    let body = responses::sse(vec![
+        responses::ev_response_created("response_1"),
+        responses::ev_assistant_message("response_1", "Task completed"),
+        responses::ev_completed("response_1"),
+    ]);
+    responses::mount_sse_once(&server, body).await;
+
+    // Create temporary directories to use with --add-dir
+    let temp_dir1 = tempfile::tempdir()?;
+    let temp_dir2 = tempfile::tempdir()?;
+
+    test.cmd_with_server(&server)
+        .arg("--skip-git-repo-check")
+        .arg("--sandbox")
+        .arg("workspace-write")
+        .arg("--add-dir")
+        .arg(temp_dir1.path())
+        .arg("--add-dir")
+        .arg(temp_dir2.path())
+        .arg("test with additional directories")
+        .assert()
+        .code(0);
+
+    Ok(())
+}
+
+/// Verify that multiple --add-dir flags can be specified.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn accepts_multiple_add_dir_flags() -> anyhow::Result<()> {
+    let test = test_codex_exec();
+
+    let server = responses::start_mock_server().await;
+    let body = responses::sse(vec![
+        responses::ev_response_created("response_1"),
+        responses::ev_assistant_message("response_1", "Multiple directories accepted"),
+        responses::ev_completed("response_1"),
+    ]);
+    responses::mount_sse_once(&server, body).await;
+
+    let temp_dir1 = tempfile::tempdir()?;
+    let temp_dir2 = tempfile::tempdir()?;
+    let temp_dir3 = tempfile::tempdir()?;
+
+    test.cmd_with_server(&server)
+        .arg("--skip-git-repo-check")
+        .arg("--sandbox")
+        .arg("workspace-write")
+        .arg("--add-dir")
+        .arg(temp_dir1.path())
+        .arg("--add-dir")
+        .arg(temp_dir2.path())
+        .arg("--add-dir")
+        .arg(temp_dir3.path())
+        .arg("test with three directories")
+        .assert()
+        .code(0);
+
+    Ok(())
+}
diff --git a/codex-rs/exec/tests/suite/mod.rs b/codex-rs/exec/tests/suite/mod.rs
index 052c43bf3..77012ee3b 100644
--- a/codex-rs/exec/tests/suite/mod.rs
+++ b/codex-rs/exec/tests/suite/mod.rs
@@ -1,4 +1,5 @@
 // Aggregates all former standalone integration tests as modules.
+mod add_dir;
 mod apply_patch;
 mod auth_env;
 mod originator;
diff --git a/sdk/typescript/src/exec.ts b/sdk/typescript/src/exec.ts
index be05e7c3e..3c47c5572 100644
--- a/sdk/typescript/src/exec.ts
+++ b/sdk/typescript/src/exec.ts
@@ -18,6 +18,8 @@ export type CodexExecArgs = {
   sandboxMode?: SandboxMode;
   // --cd
   workingDirectory?: string;
+  // --add-dir
+  additionalDirectories?: string[];
   // --skip-git-repo-check
   skipGitRepoCheck?: boolean;
   // --output-schema
@@ -58,6 +60,12 @@ export class CodexExec {
       commandArgs.push("--cd", args.workingDirectory);
     }
 
+    if (args.additionalDirectories?.length) {
+      for (const dir of args.additionalDirectories) {
+        commandArgs.push("--add-dir", dir);
+      }
+    }
+
     if (args.skipGitRepoCheck) {
       commandArgs.push("--skip-git-repo-check");
     }
diff --git a/sdk/typescript/src/thread.ts b/sdk/typescript/src/thread.ts
index 90c7a8fac..6aed29c84 100644
--- a/sdk/typescript/src/thread.ts
+++ b/sdk/typescript/src/thread.ts
@@ -90,6 +90,7 @@ export class Thread {
       networkAccessEnabled: options?.networkAccessEnabled,
       webSearchEnabled: options?.webSearchEnabled,
       approvalPolicy: options?.approvalPolicy,
+      additionalDirectories: options?.additionalDirectories,
     });
     try {
       for await (const item of generator) {
diff --git a/sdk/typescript/src/threadOptions.ts b/sdk/typescript/src/threadOptions.ts
index 77d91b89e..d81ffc60c 100644
--- a/sdk/typescript/src/threadOptions.ts
+++ b/sdk/typescript/src/threadOptions.ts
@@ -13,4 +13,5 @@ export type ThreadOptions = {
   networkAccessEnabled?: boolean;
   webSearchEnabled?: boolean;
   approvalPolicy?: ApprovalMode;
+  additionalDirectories?: string[];
 };
diff --git a/sdk/typescript/tests/run.test.ts b/sdk/typescript/tests/run.test.ts
index 1a85b5823..586e396a3 100644
--- a/sdk/typescript/tests/run.test.ts
+++ b/sdk/typescript/tests/run.test.ts
@@ -348,6 +348,48 @@ describe("Codex", () => {
     }
   });
 
+  it("passes additionalDirectories as repeated flags", async () => {
+    const { url, close } = await startResponsesTestProxy({
+      statusCode: 200,
+      responseBodies: [
+        sse(
+          responseStarted("response_1"),
+          assistantMessage("Additional directories applied", "item_1"),
+          responseCompleted("response_1"),
+        ),
+      ],
+    });
+
+    const { args: spawnArgs, restore } = codexExecSpy();
+
+    try {
+      const client = new Codex({ codexPathOverride: codexExecPath, baseUrl: url, apiKey: "test" });
+
+      const thread = client.startThread({
+        additionalDirectories: ["../backend", "/tmp/shared"],
+      });
+      await thread.run("test additional dirs");
+
+      const commandArgs = spawnArgs[0];
+      expect(commandArgs).toBeDefined();
+      if (!commandArgs) {
+        throw new Error("Command args missing");
+      }
+
+      // Find the --add-dir flags
+      const addDirArgs: string[] = [];
+      for (let i = 0; i < commandArgs.length; i += 1) {
+        if (commandArgs[i] === "--add-dir") {
+          addDirArgs.push(commandArgs[i + 1] ?? "");
+        }
+      }
+      expect(addDirArgs).toEqual(["../backend", "/tmp/shared"]);
+    } finally {
+      restore();
+      await close();
+    }
+  });
+
   it("writes output schema to a temporary file and forwards it", async () => {
     const { url, close, requests } = await startResponsesTestProxy({
       statusCode: 200,