feat: Add experimental codex tool module

[seratch]

This pull request adds a new experimental codex tool module to extensions.

import { Agent, run, generateTraceId, withTrace } from '@openai/agents';
import { codexTool } from '@openai/agents-extensions/experimental/codex';

async function main() {
  const codex = codexTool({
    sandboxMode: 'workspace-write',
    defaultThreadOptions: {
      model: 'gpt-5.2-codex',
      modelReasoningEffort: 'low',
      networkAccessEnabled: true,
      webSearchEnabled: false,
      approvalPolicy: 'never',
    },
  });
  const agent = new Agent({
    name: 'Codex Agent',
    instructions: [
      'Use the codex tool to inspect the workspace and answer the question.',
      'When skill names, which usually start with `$`, are mentioned, you must rely on the codex tool to use the skill and answer the question.',
      'When you send the final answer, you must include the following info at the end:',
      'Run `codex resume <thread_id>` to continue the codex session.',
    ].join(' '),
    tools: [codex],
  });
  const result = await run(
    agent,
    'You must use `$openai-knowledge` skill to fetch the latest realtime model name.',
  );
  console.log(result.finalOutput);
}

main().catch((error) => {
  console.error(error);
  process.exit(1);
});

see also: openai/openai-agents-python#2320

[changeset-bot]

🦋 Changeset detected

Latest commit: d57e87f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@openai/agents-extensions	Patch

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 0e872dda0b

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: d039b354ee

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".