Codex Monitor

A compact, local desktop widget for observing Codex sessions in near real time.

Codex Monitor reads locally generated rollout files from %USERPROFILE%\.codex\sessions. It never intercepts network traffic, accesses credentials, or writes to Codex files.

Features

• Live and archived session views
• Input, cached input, output, and reasoning token metrics
• Recent model-response timeline with available Codex quota when present in the local rollout
• Context-window, model-call, tool-call, and estimated output-speed telemetry
• Compact neon dark interface with an always-on-top option
• Single-instance app behavior: launching it again focuses the existing window
• Window-size persistence and minimize-on-close behavior

Run locally

Requirements: Rust, the Microsoft WebView2 Runtime, and a local Codex installation.

cargo run --offline --manifest-path .\src-tauri\Cargo.toml

The --offline flag works when the required Rust crates are already cached. Omit it on a new machine so Cargo can download dependencies.

How the data works

Codex writes structured JSONL rollout events while a task runs. The monitor follows these files incrementally, tracking only appended lines after its initial scan. “Tokens/sec” is an estimate derived from completed token-count events, rather than a server-side streaming measurement.

Quota data is displayed only when Codex includes it in a local event. It is a local snapshot of the Codex plan limit, not a billing meter.

Privacy

All monitoring remains local. The app intentionally does not read auth.json, browser data, prompts, or remote API traffic.

Support and links

• Website: andreavitolo.it
• GitHub: @AndreaZero
• Support the project: Ko-fi

License

MIT © Andrea Vitolo