Switch Model for Pi

A single switch_model tool for pi that lets the active model switch itself mid-conversation, on request, in plain language — "implement this with 5.6 sol", "switch to fable" — with no approval loop and no automatic restore. You stay on whatever model you switch to until you (or the model) call it again.

This is deliberately simpler than role-locked workflows like pi-duo's executor/reviewer setup (derived from jnsahaj/trio): there's no phase state machine, no tool-locking, no session bookkeeping. It's one tool that resolves a free-text model reference and calls pi.setModel().

Human-driven switching is already covered by pi core's built-in /model command; this package only adds the LLM-facing half.

Install

pi install npm:pi-switch-model

For local development against this checkout instead of the published package:

pi -e /path/to/pi-extensions/switch-model

Usage

Just ask, mid-conversation:

switch to 5.6 sol and implement this

The active model calls switch_model({ query: "5.6 sol" }), which resolves the query against your configured/authenticated models and switches. The rest of the conversation — history, working tree, tools — is untouched; only the model changes, and it stays changed.

Resolution

• Exact provider/id always wins outright.
• Otherwise the query is fuzzy-matched against every available model's provider/id and display name.
• One strong match → switches immediately.
• No match → fails with a ModelNotFoundError-style message listing the closest suggestions (capped at 8) so the calling model can retry with an exact id.
• Multiple matches → fails listing the tied candidates so the calling model can pick precisely.

This retry-on-error contract is the whole safety net: the tool never guesses on your behalf, and a wrong first guess self-corrects in one retry because the error itself carries the real list of available models.

Develop

npm run typecheck   # tsc --noEmit
npm test             # node --test test/core.test.ts

All resolution and formatting logic lives in src/core.ts and is pure (no ExtensionContext, no host imports) — that's the tested seam. src/index.ts is thin wiring: it maps the model registry into ModelSummarys, calls resolveModel, and turns a failure into a thrown Error so the host reports it back to the calling model as a tool error.