feat: Add support for --add-dir to exec and TypeScript SDK (#6565)

## Summary

Adds support for specifying additional directories in the TypeScript SDK
through a new `additionalDirectories` option in `ThreadOptions`.

## Changes

- Added `additionalDirectories` parameter to `ThreadOptions` interface
- Updated `CodexExec` to accept and pass through additional directories
via the `--config` flag for `sandbox_workspace_write.writable_roots`
- Added comprehensive test coverage for the new functionality

## Test plan

- Added test case that verifies `additionalDirectories` is correctly
passed as repeated flags
- Existing tests continue to pass

---------

Co-authored-by: Claude <noreply@anthropic.com>

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");
     }

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) {

sdk/typescript/src/threadOptions.ts

@@ -13,4 +13,5 @@ export type ThreadOptions = {
   networkAccessEnabled?: boolean;
   webSearchEnabled?: boolean;
   approvalPolicy?: ApprovalMode;
+  additionalDirectories?: string[];
 };