Token-budget initial context carries thread and context-window lineage that the model should treat as one structured context-window block. Wrapping it in `<context_window>` makes that boundary explicit while preserving the existing window id content. Before this change, the window identifiers were injected as an untagged developer text fragment: ```text Thread id <THREAD_ID>. First context window id: <FIRST_WINDOW_ID> Current context window id: <WINDOW_ID> Previous context window id: <PREVIOUS_WINDOW_ID> ``` After this change, the same payload is wrapped as a context-window block: ```text <context_window> Thread id: <THREAD_ID> First context window id: <FIRST_WINDOW_ID> Current context window id: <WINDOW_ID> Previous context window id: <PREVIOUS_WINDOW_ID> </context_window> ``` This adds shared `CONTEXT_WINDOW_*_TAG` protocol constants, updates `TokenBudgetContext` to render with those markers, treats the new wrapper as contextual developer content when mapping history, and refreshes the token-budget request-shape assertions and snapshot. Verification: - `just test -p codex-core token_budget` - `just test -p codex-core recognizes_context_window_as_contextual_developer_content`
Codex CLI is a coding agent from OpenAI that runs locally on your computer.
If you want Codex in your code editor (VS Code, Cursor, Windsurf), install in your IDE.
If you want the desktop app experience, run
codex app or visit the Codex App page.
If you are looking for the cloud-based agent from OpenAI, Codex Web, go to chatgpt.com/codex.
Quickstart
Installing and running Codex CLI
Run the following on Mac or Linux to install Codex CLI:
curl -fsSL https://chatgpt.com/codex/install.sh | sh
Run the following on Windows to install Codex CLI:
powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"
Codex CLI can also be installed via the following package managers:
# Install using npm
npm install -g @openai/codex
# Install using Homebrew
brew install --cask codex
Then simply run codex to get started.
You can also go to the latest GitHub Release and download the appropriate binary for your platform.
Each GitHub Release contains many executables, but in practice, you likely want one of these:
- macOS
- Apple Silicon/arm64:
codex-aarch64-apple-darwin.tar.gz - x86_64 (older Mac hardware):
codex-x86_64-apple-darwin.tar.gz
- Apple Silicon/arm64:
- Linux
- x86_64:
codex-x86_64-unknown-linux-musl.tar.gz - arm64:
codex-aarch64-unknown-linux-musl.tar.gz
- x86_64:
Each archive contains a single entry with the platform baked into the name (e.g., codex-x86_64-unknown-linux-musl), so you likely want to rename it to codex after extracting it.
Using Codex with your ChatGPT plan
Run codex and select Sign in with ChatGPT. We recommend signing into your ChatGPT account to use Codex as part of your Plus, Pro, Business, Edu, or Enterprise plan. Learn more about what's included in your ChatGPT plan.
You can also use Codex with an API key, but this requires additional setup.
Docs
This repository is licensed under the Apache-2.0 License.
