Large Language Models
Mike Slinn

Codex: Agentic Programming with ChatGPT in Visual Studio Code

Published 2025-10-17.
Time to read: 2 minutes.

This page is part of the llm collection.

Somehow I did not get around to trying to generate software with OpenAI products until now.

Codex – OpenAI’s coding agent

Shell
$ code --install-extension openai.chatgpt
Installing extensions...
Installing extension 'openai.chatgpt'...
Extension 'openai.chatgpt' v0.4.19 was successfully installed.

Plus Plan Required for Codex

In Canada, ChatGPT Plus costs US $20/month plus taxes, which ends up being ~ CAD $27-30/month depending on the province and exchange rates.

If you subscribe via Apple’s Canadian App Store, there’s a fixed rate: CAD $24.99/month, or CAD $249/year for the annual plan.

Local Deepseek Instance

The wassimdev-vscode-deepseek extension for Visual Studio Code repurposes the openai.chatgpt extension so it works with a local instance of a Deepseek LLM. This is possible because Deepseek implements the OpenAI API.

To install via the command line:

Shell
$ code --install-extension wassimdev.wassimdev-vscode-deepseek

If your Deepseek LLM is not running on the same machine that you use for programming, you can configure the URL that specifies where to find it. You might need to open firewalls to allow traffic on port 11434.

Verify that all is in order:

  1. The ollama app is installed and running on your local machine, which might not be the machine that runs the Deepseek LLM. For Windows computers, this is a native Windows application. Visit ollama.com for more details.
  2. The Ollama server is running at http://localhost:11434, or wherever you installed it.
  3. The Ollama server URL is correct in your settings.json: "deepseek.ollama.host": "http://localhost:11434".
  4. The Ollama server is accessible from this network.

Then open a new OpenAI ChatGPT session and type @deepseek.

Error: [object Object]

The error message "Error: [object Object]" in the context of ChatGPT within VS Code typically indicates that a JavaScript object is being implicitly converted to a string when it should be handled differently, or that there's an issue with how data is being passed or received by the ChatGPT extension or API.

Here's how to address this error:

    1. Ensure the ChatGPT or CodeGPT extension in VS Code is correctly installed and configured with an OpenAI API key.
    2. Real Programmers Pumping It Up
      Real Programmers Pumping It Up
      Verify that the API key is active and has the necessary permissions.

      A quick online search brought me to the OpenAI API Key Harvester Tester. Nope. Not for me!

      The incantation below is how real programmers test the validity of an OpenAI API key store in an environment variable called OPENAI_API_KEY. This incantation just asks OpenAI for the current list of available models:
      Shell
      $ curl https://api.openai.com/v1/models \
  -H "Authorization: Bearer $OPENAI_API_KEY"
{
"object": "list",
"data": [
  {
    "id": "gpt-3.5-turbo",
    "object": "model",
    "created": 1677610602,
    "owned_by": "openai"
  },
  {
    "id": "gpt-5-search-api-2025-10-14",
    "object": "model",
    "created": 1760043960,
    "owned_by": "system"
  },
  {
    "id": "gpt-audio-mini-2025-10-06",
    "object": "model",
    "created": 1759512137,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-search-api",
    "object": "model",
    "created": 1759514629,
    "owned_by": "system"
  },
  {
    "id": "sora-2",
    "object": "model",
    "created": 1759708615,
    "owned_by": "system"
  },
  {
    "id": "sora-2-pro",
    "object": "model",
    "created": 1759708663,
    "owned_by": "system"
  },
  {
    "id": "davinci-002",
    "object": "model",
    "created": 1692634301,
    "owned_by": "system"
  },
  {
    "id": "babbage-002",
    "object": "model",
    "created": 1692634615,
    "owned_by": "system"
  },
  {
    "id": "gpt-3.5-turbo-instruct",
    "object": "model",
    "created": 1692901427,
    "owned_by": "system"
  },
  {
    "id": "gpt-3.5-turbo-instruct-0914",
    "object": "model",
    "created": 1694122472,
    "owned_by": "system"
  },
  {
    "id": "dall-e-3",
    "object": "model",
    "created": 1698785189,
    "owned_by": "system"
  },
  {
    "id": "dall-e-2",
    "object": "model",
    "created": 1698798177,
    "owned_by": "system"
  },
  {
    "id": "gpt-3.5-turbo-1106",
    "object": "model",
    "created": 1698959748,
    "owned_by": "system"
  },
  {
    "id": "tts-1-hd",
    "object": "model",
    "created": 1699046015,
    "owned_by": "system"
  },
  {
    "id": "tts-1-1106",
    "object": "model",
    "created": 1699053241,
    "owned_by": "system"
  },
  {
    "id": "tts-1-hd-1106",
    "object": "model",
    "created": 1699053533,
    "owned_by": "system"
  },
  {
    "id": "text-embedding-3-small",
    "object": "model",
    "created": 1705948997,
    "owned_by": "system"
  },
  {
    "id": "text-embedding-3-large",
    "object": "model",
    "created": 1705953180,
    "owned_by": "system"
  },
  {
    "id": "gpt-3.5-turbo-0125",
    "object": "model",
    "created": 1706048358,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o",
    "object": "model",
    "created": 1715367049,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-2024-05-13",
    "object": "model",
    "created": 1715368132,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-2024-07-18",
    "object": "model",
    "created": 1721172717,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini",
    "object": "model",
    "created": 1721172741,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-2024-08-06",
    "object": "model",
    "created": 1722814719,
    "owned_by": "system"
  },
  {
    "id": "o1-mini-2024-09-12",
    "object": "model",
    "created": 1725648979,
    "owned_by": "system"
  },
  {
    "id": "o1-mini",
    "object": "model",
    "created": 1725649008,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-audio-preview-2024-10-01",
    "object": "model",
    "created": 1727389042,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-audio-preview",
    "object": "model",
    "created": 1727460443,
    "owned_by": "system"
  },
  {
    "id": "omni-moderation-latest",
    "object": "model",
    "created": 1731689265,
    "owned_by": "system"
  },
  {
    "id": "omni-moderation-2024-09-26",
    "object": "model",
    "created": 1732734466,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-audio-preview-2024-12-17",
    "object": "model",
    "created": 1734034239,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-audio-preview-2024-12-17",
    "object": "model",
    "created": 1734115920,
    "owned_by": "system"
  },
  {
    "id": "o1-2024-12-17",
    "object": "model",
    "created": 1734326976,
    "owned_by": "system"
  },
  {
    "id": "o1",
    "object": "model",
    "created": 1734375816,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-audio-preview",
    "object": "model",
    "created": 1734387424,
    "owned_by": "system"
  },
  {
    "id": "o3-mini",
    "object": "model",
    "created": 1737146383,
    "owned_by": "system"
  },
  {
    "id": "o3-mini-2025-01-31",
    "object": "model",
    "created": 1738010200,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-2024-11-20",
    "object": "model",
    "created": 1739331543,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-search-preview-2025-03-11",
    "object": "model",
    "created": 1741388170,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-search-preview",
    "object": "model",
    "created": 1741388720,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-search-preview-2025-03-11",
    "object": "model",
    "created": 1741390858,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-search-preview",
    "object": "model",
    "created": 1741391161,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-transcribe",
    "object": "model",
    "created": 1742068463,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-transcribe",
    "object": "model",
    "created": 1742068596,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-mini-tts",
    "object": "model",
    "created": 1742403959,
    "owned_by": "system"
  },
  {
    "id": "o3-2025-04-16",
    "object": "model",
    "created": 1744133301,
    "owned_by": "system"
  },
  {
    "id": "o4-mini-2025-04-16",
    "object": "model",
    "created": 1744133506,
    "owned_by": "system"
  },
  {
    "id": "o3",
    "object": "model",
    "created": 1744225308,
    "owned_by": "system"
  },
  {
    "id": "o4-mini",
    "object": "model",
    "created": 1744225351,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1-2025-04-14",
    "object": "model",
    "created": 1744315746,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1",
    "object": "model",
    "created": 1744316542,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1-mini-2025-04-14",
    "object": "model",
    "created": 1744317547,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1-mini",
    "object": "model",
    "created": 1744318173,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1-nano-2025-04-14",
    "object": "model",
    "created": 1744321025,
    "owned_by": "system"
  },
  {
    "id": "gpt-4.1-nano",
    "object": "model",
    "created": 1744321707,
    "owned_by": "system"
  },
  {
    "id": "gpt-image-1",
    "object": "model",
    "created": 1745517030,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-audio-preview-2025-06-03",
    "object": "model",
    "created": 1748908498,
    "owned_by": "system"
  },
  {
    "id": "gpt-4o-transcribe-diarize",
    "object": "model",
    "created": 1750798887,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-chat-latest",
    "object": "model",
    "created": 1754073306,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-2025-08-07",
    "object": "model",
    "created": 1754075360,
    "owned_by": "system"
  },
  {
    "id": "gpt-5",
    "object": "model",
    "created": 1754425777,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-mini-2025-08-07",
    "object": "model",
    "created": 1754425867,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-mini",
    "object": "model",
    "created": 1754425928,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-nano-2025-08-07",
    "object": "model",
    "created": 1754426303,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-nano",
    "object": "model",
    "created": 1754426384,
    "owned_by": "system"
  },
  {
    "id": "gpt-audio-2025-08-28",
    "object": "model",
    "created": 1756256146,
    "owned_by": "system"
  },
  {
    "id": "gpt-audio",
    "object": "model",
    "created": 1756339249,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-codex",
    "object": "model",
    "created": 1757527818,
    "owned_by": "system"
  },
  {
    "id": "gpt-image-1-mini",
    "object": "model",
    "created": 1758845821,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-pro-2025-10-06",
    "object": "model",
    "created": 1759469707,
    "owned_by": "system"
  },
  {
    "id": "gpt-5-pro",
    "object": "model",
    "created": 1759469822,
    "owned_by": "system"
  },
  {
    "id": "gpt-audio-mini",
    "object": "model",
    "created": 1759512027,
    "owned_by": "system"
  },
  {
    "id": "whisper-1",
    "object": "model",
    "created": 1677532384,
    "owned_by": "openai-internal"
  },
  {
    "id": "tts-1",
    "object": "model",
    "created": 1681940951,
    "owned_by": "openai-internal"
  },
  {
    "id": "gpt-3.5-turbo-16k",
    "object": "model",
    "created": 1683758102,
    "owned_by": "openai-internal"
  },
  {
    "id": "text-embedding-ada-002",
    "object": "model",
    "created": 1671217299,
    "owned_by": "openai-internal"
  }
]
      }
  2. I cannot inspect the API responses.
  3. Troubleshoot the VS Code Extension:
    1. Restart VS Code: A simple restart can resolve temporary glitches.
    2. Update Extension: Ensure the ChatGPT or CodeGPT extension is updated to the latest version.
    3. Disable/Re-enable Extension: Try disabling and then re-enabling the extension in VS Code.
    4. Reinstall Extension: If the above steps fail, consider uninstalling and reinstalling the extension.
  4. Check the OpenAI Status page.

References

Support.

Front page
Expert witness USA
32 articles on LLMs
Studio technology USA
Original music by Mike Slinn
Windows Subsystem for Linux topics
General topics
Jekyll-generated websites USA
Git and libgit2 USA
Mainframe image; Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License by PekoeBlaze
Go language articles
Ruby language USA
Django-powered e-commerce USA
World Peace Musical Collective
* indicates a required field.

Please select the following to receive Mike Slinn’s newsletter:

You can unsubscribe at any time by clicking the link in the footer of emails.

Mike Slinn uses Mailchimp as his marketing platform. By clicking below to subscribe, you acknowledge that your information will be transferred to Mailchimp for processing. Learn more about Mailchimp’s privacy practices.