openai-fast

A pi extension that enables OpenAI Codex Fast mode for ChatGPT-auth GPT-5.4 and GPT-5.5.

When active, the extension injects this into eligible OpenAI Codex request payloads:

{
  "service_tier": "priority"
}

The user-facing feature is OpenAI Codex Fast mode. The wire value is priority because current Codex clients map Fast mode to the OpenAI priority service tier.

Eligibility

Fast mode is only injected when all of these are true:

• The current provider is openai-codex.
• The current API is openai-codex-responses.
• The current model is gpt-5.4 or gpt-5.5.
• The provider is using ChatGPT OAuth/subscription auth, not API-key auth.
• The request payload does not already include service_tier.

Commands

/fast
/fast status
/fast on
/fast off
/fast auto
/fast toggle

Run /fast without arguments to pick an action from a menu. /fast on and /fast off are temporary session/runtime overrides. Use /fast auto to reload and follow config defaults again.

The extension defaults to off so installing the full collection does not accidentally spend Fast-mode credits.

Config

Optional global config:

~/.pi/agent/extensions/openai-fast.json

Optional project config:

.pi/openai-fast.json

Project config overrides global config.

{
  "enabled": false,
  "showStatus": true
}

• enabled: default Fast-mode state when there is no session override.
• showStatus: show a compact fast status when Fast mode is active for the current model.

Install

Standalone npm package

pi install npm:@diegopetrucci/pi-openai-fast

Collection package

pi install npm:@diegopetrucci/pi-extensions

GitHub package

pi install git:github.com/diegopetrucci/pi-extensions

Then reload pi:

/reload

Notes

• This extension intentionally does not affect API-key OpenAI models.
• Pi may only account Fast-mode cost correctly when the backend reports service_tier: "priority" in the streamed response. The extension does not patch usage totals to avoid double-counting.
• If pi adds first-class service-tier support later, this extension skips payloads that already contain service_tier.