## Why PR #29494 made context-window IDs visible to the model by wrapping the token-budget window payload in `<context_window>`, but rollout JSONL consumers still could not see the initial window identity by tailing the session file. Compacted rollout items carry window IDs only after compaction has happened, so a session with no compaction had no durable JSONL record for window 0. This change gives tailing consumers a stable initial-window record at session creation time. ## What Changed - Added `session_meta.context_window.window_id` for the initial context-window identity. - `CreateThreadParams` now requires `initial_window_id: String`, so thread-store callers cannot accidentally create new threads without window-0 metadata. - Live thread creation derives the persisted initial window ID from the same `AutoCompactWindowIds` used to initialize `SessionState`, keeping runtime state and JSONL metadata aligned. - Rollout reconstruction uses `session_meta.context_window.window_id` as the initial-window fallback and derives `window_number = 0`, `first_window_id = window_id`, and `previous_window_id = None` internally. - Fork reconstruction intentionally uses the same rollout reconstruction path; consumers that need to distinguish copied initial-window metadata can use the rollout `thread_id`. - Legacy compactions without `window_number` still use compaction-count fallback accounting instead of being reset to window 0 by the initial-window fallback. - Compacted rollout metadata still takes precedence once compaction records exist, preserving the richer chain fields there. ## JSONL Shape Real rollout JSONL is one object per line. This example is expanded for readability, but shows the new initial `session_meta.context_window` record followed by the existing compacted rollout item shape that also carries window IDs: ```jsonl { "timestamp": "2026-06-22T12:00:00.000Z", "type": "session_meta", "payload": { "session_id": "<THREAD_ID>", "id": "<THREAD_ID>", "timestamp": "2026-06-22T12:00:00.000Z", "cwd": "/repo", "originator": "codex", "cli_version": "0.0.0", "source": "cli", "model_provider": "<MODEL_PROVIDER>", "context_window": { "window_id": "<INITIAL_WINDOW_ID>" } } } ... { "timestamp": "2026-06-22T12:34:56.000Z", "type": "compacted", "payload": { "message": "<COMPACTION_SUMMARY>", "replacement_history": [ "..." ], "window_number": 1, "first_window_id": "<INITIAL_WINDOW_ID>", "previous_window_id": "<INITIAL_WINDOW_ID>", "window_id": "<NEXT_WINDOW_ID>" } } ``` The nested `context_window` object is intentional: it gives rollout consumers a stable namespace for context-window metadata while only writing the non-derivable initial `window_id`. For the initial window, `window_number`, `first_window_id`, and `previous_window_id` are derived internally instead of being written to the rollout. ## Verification - `just test -p codex-protocol` - `just test -p codex-rollout recorder_materializes_on_flush_with_pending_items` - `just test -p codex-core reconstruct_history` - `just test -p codex-core record_initial_history_reconstructs_forked_transcript` - `just test -p codex-thread-store` - `just test -p codex-state` - `just test -p codex-app-server thread_read_returns_summary_without_turns` - `just test -p codex-rollout persistence_metrics`
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.
