Curtis 'Fjord' Hawthorne
eb77db2957
## Summary - add tracing-based diagnostics for nested `codex.tool(...)` calls made from `js_repl` - emit a bounded, sanitized summary at `info!` - emit the exact raw serialized response object or error string seen by JavaScript at `trace!` - document how to enable these logs and where to find them, especially for `codex app-server` ## Why Nested `codex.tool(...)` calls inside `js_repl` are a debugging boundary: JavaScript sees the tool result, but that result is otherwise hard to inspect from outside the kernel. This change adds explicit tracing for that path using the repo’s normal observability pattern: - `info` for compact summaries - `trace` for exact raw payloads when deep debugging is needed ## What changed - `js_repl` now summarizes nested tool-call results across the response shapes it can receive: - message content - function-call outputs - custom tool outputs - MCP tool results and MCP error results - direct error strings - each nested `codex.tool(...)` completion logs: - `exec_id` - `tool_call_id` - `tool_name` - `ok` - a bounded summary struct describing the payload shape - at `trace`, the same path also logs the exact serialized response object or error string that JavaScript received - docs now include concrete logging examples for `codex app-server` - unit coverage was added for multimodal function output summaries and error summaries ## How to use it ### Summary-only logging Set: ```sh RUST_LOG=codex_core::tools::js_repl=info ``` For `codex app-server`, tracing output is written to the server process `stderr`. Example: ```sh RUST_LOG=codex_core::tools::js_repl=info \ LOG_FORMAT=json \ codex app-server \ 2> /tmp/codex-app-server.log ``` This emits bounded summary lines for nested `codex.tool(...)` calls. ### Full raw debugging Set: ```sh RUST_LOG=codex_core::tools::js_repl=trace ``` Example: ```sh RUST_LOG=codex_core::tools::js_repl=trace \ LOG_FORMAT=json \ codex app-server \ 2> /tmp/codex-app-server.log ``` At `trace`, you get: - the same `info` summary line - a `trace` line with the exact serialized response object seen by JavaScript - or the exact error string if the nested tool call failed ### Where the logs go For `codex app-server`, these logs go to process `stderr`, so redirect or capture `stderr` to inspect them. Example: ```sh RUST_LOG=codex_core::tools::js_repl=trace \ LOG_FORMAT=json \ /Users/fjord/code/codex/codex-rs/target/debug/codex app-server \ 2> /tmp/codex-app-server.log ``` Then inspect: ```sh rg "js_repl nested tool call" /tmp/codex-app-server.log ``` Without an explicit `RUST_LOG` override, these `js_repl` nested tool-call logs are typically not visible.
Codex CLI (Rust Implementation)
We provide Codex CLI as a standalone, native executable to ensure a zero-dependency install.
Installing Codex
Today, the easiest way to install Codex is via npm:
npm i -g @openai/codex
codex
You can also install via Homebrew (brew install --cask codex) or download a platform-specific release directly from our GitHub Releases.
Documentation quickstart
- First run with Codex? Start with
docs/getting-started.md(links to the walkthrough for prompts, keyboard shortcuts, and session management). - Want deeper control? See
docs/config.mdanddocs/install.md.
What's new in the Rust CLI
The Rust implementation is now the maintained Codex CLI and serves as the default experience. It includes a number of features that the legacy TypeScript CLI never supported.
Config
Codex supports a rich set of configuration options. Note that the Rust CLI uses config.toml instead of config.json. See docs/config.md for details.
Model Context Protocol Support
MCP client
Codex CLI functions as an MCP client that allows the Codex CLI and IDE extension to connect to MCP servers on startup. See the configuration documentation for details.
MCP server (experimental)
Codex can be launched as an MCP server by running codex mcp-server. This allows other MCP clients to use Codex as a tool for another agent.
Use the @modelcontextprotocol/inspector to try it out:
npx @modelcontextprotocol/inspector codex mcp-server
Use codex mcp to add/list/get/remove MCP server launchers defined in config.toml, and codex mcp-server to run the MCP server directly.
Notifications
You can enable notifications by configuring a script that is run whenever the agent finishes a turn. The notify documentation includes a detailed example that explains how to get desktop notifications via terminal-notifier on macOS. When Codex detects that it is running under WSL 2 inside Windows Terminal (WT_SESSION is set), the TUI automatically falls back to native Windows toast notifications so approval prompts and completed turns surface even though Windows Terminal does not implement OSC 9.
codex exec to run Codex programmatically/non-interactively
To run Codex non-interactively, run codex exec PROMPT (you can also pass the prompt via stdin) and Codex will work on your task until it decides that it is done and exits. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on.
Use codex exec --ephemeral ... to run without persisting session rollout files to disk.
Experimenting with the Codex Sandbox
To test to see what happens when a command is run under the sandbox provided by Codex, we provide the following subcommands in Codex CLI:
# macOS
codex sandbox macos [--full-auto] [--log-denials] [COMMAND]...
# Linux
codex sandbox linux [--full-auto] [COMMAND]...
# Windows
codex sandbox windows [--full-auto] [COMMAND]...
# Legacy aliases
codex debug seatbelt [--full-auto] [--log-denials] [COMMAND]...
codex debug landlock [--full-auto] [COMMAND]...
Selecting a sandbox policy via --sandbox
The Rust CLI exposes a dedicated --sandbox (-s) flag that lets you pick the sandbox policy without having to reach for the generic -c/--config option:
# Run Codex with the default, read-only sandbox
codex --sandbox read-only
# Allow the agent to write within the current workspace while still blocking network access
codex --sandbox workspace-write
# Danger! Disable sandboxing entirely (only do this if you are already running in a container or other isolated env)
codex --sandbox danger-full-access
The same setting can be persisted in ~/.codex/config.toml via the top-level sandbox_mode = "MODE" key, e.g. sandbox_mode = "workspace-write".
Code Organization
This folder is the root of a Cargo workspace. It contains quite a bit of experimental code, but here are the key crates:
core/contains the business logic for Codex. Ultimately, we hope this to be a library crate that is generally useful for building other Rust/native applications that use Codex.exec/"headless" CLI for use in automation.tui/CLI that launches a fullscreen TUI built with Ratatui.cli/CLI multitool that provides the aforementioned CLIs via subcommands.
If you want to contribute or inspect behavior in detail, start by reading the module-level README.md files under each crate and run the project workspace from the top-level codex-rs directory so shared config, features, and build scripts stay aligned.