pi-fast

Use provider fast modes in Pi when you need lower latency, while keeping the paid path off by default.

pi-fast currently supports OpenAI Codex models that advertise Fast processing. It adds Codex's priority service tier after you enable it for the session or opt in to the global default.

Features

• On-demand toggle — use /fast, /fast on, /fast off, or Ctrl+Shift+R.
• Safe model guard — only supported openai-codex models receive the Fast request field.
• Visible state — the Pi footer shows Fast on, Fast off, or Fast n/a.
• Configurable default — opt in once to start Fast mode on for every supported model.
• Session-local overrides — command and shortcut changes reset to the configured default for each session.

Supported models

The current OpenAI Codex catalog advertises Fast support for:

• gpt-6-astra
• gpt-5.4
• gpt-5.5
• gpt-5.6-luna
• gpt-5.6-sol
• gpt-5.6-terra

The support list follows the upstream Codex model catalog and may need an update when that catalog changes. Models without an advertised Fast tier are left untouched.

Checked against openai/codex commit 654b0a77d0d2f81aa21f61caf7af4be88fe550bb (2026-09-11). This package uses the Codex subscription backend, not the public OpenAI API. Fast mode consumes more subscription usage. Public API dollar prices and Pi's token-cost estimates are not your ChatGPT credit bill. Consult Codex speed documentation for current plan rates and availability. No latency guarantee is made.

Installation

Install from npm:

pi install npm:pi-fast

Install project-locally with Pi's -l flag:

pi install -l npm:pi-fast

During local development from this monorepo:

pi install /path/to/pi-mono/packages/pi-fast

For a one-off run without installing:

pi -e /path/to/pi-mono/packages/pi-fast

This is an npm-compatible TypeScript Pi package. There is no runtime build step. With an updated pi-codex-compaction installed, the same Fast toggle also applies to its direct compaction requests through Pi's event bus.

Usage

Start a supported Codex model, then use either:

/fast

or press Ctrl+Shift+R.

/fast toggles the current state. /fast on, /fast off, and /fast toggle select it explicitly. When active, supported Codex requests include service_tier: "priority", which upstream describes as faster processing with increased usage.

Configuration

Fast mode remains off by default. To start every session with Fast mode enabled for all supported models, add this setting to Pi's global settings.json (normally ~/.pi/agent/settings.json, or the configured agent directory):

{
  "pi-fast": {
    "enabledByDefault": true
  }
}

This is a global opt-in because the priority service tier can increase provider usage. Unsupported provider/model pairs remain unchanged. /fast off disables Fast mode for the current session; starting, switching, or reloading a session restores the configured default.

Install/update telemetry can be disabled with PI_OFFLINE=1 or PI_TELEMETRY=0.

Development

npm install
npm run -w packages/pi-fast check
npm test -w packages/pi-fast
npm run -w packages/pi-fast pack:dry-run

Smoke test (Pi 0.85.1 or later): select openai-codex/gpt-6-astra, enable /fast on, and send a short prompt. Check Fast on. Switch to a different provider and check Fast n/a. Switch back, run /fast off, and check Fast off.