Agent field guideCoding harness
OpenAI Codex
situationalOpenAI · stable · osi-open-source
OpenAI coding harness spanning terminal CLI, IDE, and cloud tasks on ChatGPT plans.
Visit github.com →Open in NoemiumCatalog cardSource verified 2026-08-26
ledger entry · observed by @whysanesanders
Lowest-friction OpenAI coding agent if you already pay for ChatGPT. Caps sit on a five-hour window and credits replaced per-message billing.
layer
Coding harness
maturity
stable
deployment
local · hybrid · managed
evidence
Source verified
Install
Best for
- Repo work on an OpenAI seat you already have
- Mixed local CLI and cloud tasks inside the ChatGPT plan
Requirements
- A ChatGPT account or OpenAI API key
- Node.js for the CLI install path
Real cost scenarios
ChatGPT Plus
$20/mo
Plus list; cloud GitHub review is Plus-and-up. Local CLI can also burn API credits.
ChatGPT Pro 20x
$200/mo
Pro 20x list; extra credits after the 5-hour window.
Models and providers
ChatGPT Free/Go/Plus/ProOpenAI API
Channels and surfaces
interactive terminalIDEcloud tasks
Security boundary
high privilegeConversation and repo context leave for OpenAI hosted agents. Local CLI still sends prompts to OpenAI unless you point it at a custom endpoint the docs currently allow.
- Cloud tasks are Plus-and-up and run off your machine.
- Do not treat the 5-hour window as a hard sandbox.
Known limitations
- Local and cloud usage share a rolling 5-hour window.
- Token-credit metering makes a session cost hard to predict.
- No self-host of the hosted cloud agent.
Typed evidence
- 1Availabilitygithub.com/openai/codexchecked 2026-08-26
- 2Installgithub.com/openai/codexchecked 2026-08-26
- 3Requirementsgithub.com/openai/codexchecked 2026-08-26
- 4Pricinggithub.com/openai/codexchecked 2026-08-26
- 5Security / threat modelgithub.com/openai/codexchecked 2026-08-26
- 6Licensegithub.com/openai/codexchecked 2026-08-26