pi-cost

Estimated session cost in the pi footer, priced at a reference model of your choice from the OpenRouter catalog. This is a pricing lens — pi's actual model/provider is never changed.

The built-in footer already shows token stats; pi-cost adds a status line:

$0.0750 @ openai/gpt-6-astra

The cost updates live on message_update (streaming) and settles on turn_end.

Install

From npm:

pi install npm:pi-cost-was-taken

Or for a single run without installing: pi -e npm:pi-cost-was-taken.

No build step, no runtime dependencies — pi loads the TypeScript directly.

Copy extensions/index.ts to ~/.pi/agent/extensions/pi-cost/index.ts (or .pi/extensions/pi-cost/index.ts for a project).

Restart pi (or /reload).

Commands

Command	Effect
/cost	Token sums + current cost + reference model, with usage hints
/cost pick	Prompts for a search term, then lists all matching models (blank = all 400+, by context length)
/cost pick claude	Skips the prompt, lists all models matching the substring (id or name, case-insensitive)
/cost claude	Same as above — substring sugar
/cost usd / /cost inr	Currency for the cost display (persisted)

The reference model and currency persist across restarts. If you switch pi's actual model and that model exists in the catalog, the reference model follows it (reference-only, not persisted).

Pricing assumptions (read before trusting the number)

• Catalog: GET https://openrouter.ai/api/v1/models (free, no auth), cached for 24 h at ~/.pi/agent/extensions/pi-cost/catalog.json. On network failure the stale cache is used; with no cache at all the line shows cost: n/a.
• Cache prices: OpenRouter publishes cache read/write prices for only some models. Where absent, reads and writes are charged at the full input price — a conservative ceiling, never an underestimate.
• Per-request fees (pricing.request) are ignored.
• FX rate: GET https://open.er-api.com/v6/latest/USD, fetched fresh at every session start and stored in catalog.json. On failure the last cached rate is used; if there is none ever, a hardcoded 85 (display-only fallback).

Files

Path	Contents
~/.pi/agent/extensions/pi-cost/catalog.json	Cached catalog + fxInr (auto-managed)
~/.pi/agent/extensions/pi-cost/state.json	{ modelId, currency } (auto-managed)

Delete catalog.json to force a refetch; delete state.json to reset model/currency to defaults.

Development

node --experimental-strip-types check.ts   # pure-function self-checks
pi -e ./extensions/index.ts                # interactive session with the extension
pi -p "hi" -e ./extensions/index.ts        # headless smoke test (no dialogs)