## Why Follow-up to #29249 and its [compaction review thread](https://github.com/openai/codex/pull/29249#discussion_r3455055101). During a turn, environment readiness can change between sampling requests. Inline compaction must render the same model-visible `WorldState` used by the request it follows. Rebuilding that state during compaction can observe a newer environment, make replacement history disagree with what the model saw, and suppress the next environment update. ## What changed - Make `run_turn` own the current `Arc<WorldState>` and replace it only between sampling requests. - Build each state from an explicitly chosen environment snapshot, diff deferred-executor steps against the turn-owned state, and retain the latest state in `ContextManager` only for cross-turn and resume tracking. - Pass the exact turn-owned state into inline compaction and explicit new-context-window replacement. - Carry that state with `InitialContextInjection::BeforeLastUserMessage`, so replacement context and its stored baseline cannot come from different snapshots. - Remove obsolete state-recapture helpers and ambiguous TurnContext-only WorldState builders. - Add an integration test that moves an environment from starting to ready during a paused turn, triggers compaction, and verifies the next request receives the readiness update exactly once. ## Test plan - `just test -p codex-core deferred_executor_compaction_preserves_then_updates_environment_once` - `just test -p codex-core process_compacted_history` - `just test -p codex-core mid_turn_continuation_compaction` - `just test -p codex-core build_initial_context` - `just test -p codex-core ignores_session_prefix_messages_when_truncating`
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.
