dotfiles/pi/extensions/openai-codex-fast/README.md

OpenAI Codex fast mode

Adds /fast for Pi's openai-codex provider and openai-codex-responses API. When enabled, the extension adds service_tier: "priority" to matching requests. It keeps the selected model, reasoning level, tools, and conversation input.

Usage

• /fast toggles fast mode.
• /fast on requests priority service. Usage may increase.
• /fast off stops this extension's override and restores provider defaults.
• /fast status reports the setting without changing it.

New sessions start with fast mode off. Changes are stored as custom session entries, outside model context. Resume and reload restore the active branch's setting. Forks inherit only settings before the fork point. Switching to another provider makes the setting inactive; switching back to Codex reactivates it. Changes require an idle session. Status reports remain available during a turn.

The footer shows Codex fast: priority while this extension requests priority service. This shows the requested tier, not confirmation from OpenAI.

Availability and usage

OpenAI controls priority access for each model and account. Priority service can increase subscription usage or cost. The extension does not change reasoning settings, query Codex's model catalog, verify account eligibility, or guarantee faster responses. Unlike the Codex CLI, it does not hide the command for models without an advertised fast tier. API failures use Pi's normal error handling; the extension does not silently retry with another tier.

Other providers are untouched, including openai, OpenRouter, and providers that reuse the Codex API under another name. While enabled, this extension replaces any existing service_tier value with priority. Disabling it leaves native request settings and other extensions' overrides unchanged.

Your openai-server-compaction extension can remain enabled. Both request patches preserve unrelated fields. Fast mode applies to normal session requests, not the compaction extension's separate HTTP compaction or summary calls.

Installation

Home Manager deploys this directory through rsydn.aiTools.piExtensions along with the other extensions. Apply your usual dotfiles rebuild, then run /reload. To test before deploying:

pi -e ./pi/extensions/openai-codex-fast/index.ts

Codex implementation reference

Reviewed OpenAI Codex commit 1a69ad3237fc.

• Service-tier UI toggles the model's advertised Fast tier and persists the selection.
• Model catalog identifies Fast with the request value priority.
• Request builder sends the selected tier in service_tier.

Pi's before_provider_request hook changes the native payload. No provider replacement, custom transport, or additional runtime dependency is required.

Tests

Requires Node.js 22.19 or newer and an installed pi executable. Tested with Pi 1.1.0.

node --experimental-strip-types --test \
  pi/extensions/openai-codex-fast/tests/*.test.ts \
  pi/extensions/openai-codex-fast/tests/*.test.cjs

Unit tests cover scope, payload preservation, branch state, and both compaction patch orders. The runtime test uses Pi's real loader and native providers with a local HTTP fixture. It checks outgoing payloads, commands, the idle guard, provider switching, resume, and forks. It sends no requests to OpenAI and uses no real credentials.