Ultramarine (Paper Instruments)

Ultramarine is Paper Instruments' open-weight, knowledge-work model, reached over an Anthropic-compatible Messages API. In Omniscio it is a first-class provider: the standard claude harness runs a session as usual and only the endpoint and the key change, so everything you know about a session — resume, compaction, tool approvals, the context bar — keeps working.

Use it when you want a cheap, capable workhorse on your own Paper Instruments key. There is no Omniscio credit lane for this vendor, so nothing is pooled or funded on your behalf.

Before you start

Add funds first. The API is prepaid: create an account at platform.paperinstruments.com, add funds on its billing page, then create an API key. A key with an empty balance answers 429 insufficient_quota.
One model only. The endpoint accepts exactly ultramarine-1-flash; any other model name is a 404, so Omniscio offers that single choice.

Setting it up in Omniscio

Settings → Providers → Ultramarine.
Turn on Allow Ultramarine sessions in any project. It ships off, like every provider.
Paste your key into Ultramarine API Key. Omniscio checks it against the vendor's own endpoint before saving, and stores it encrypted at rest.
Pick Ultramarine in the new-session menu.

What it costs

Token type	Price per million
Input	$0.15
Cached input	$0.03
Output (including reasoning)	$0.50

A session's spend is recorded at those rates. The "$0.13 per task" figure in the launch announcement is Paper Instruments' own estimate for a sample task, not a price you are charged.

How it behaves

Reasoning is always on. The vendor defaults to maximum effort and offers only low, high and max. Omniscio maps any other level onto the nearest of those, so a session never sends one the endpoint rejects.
Context. The window is 131,072 tokens; Omniscio asks the harness to compact inside it, which reserves ~33k for the reply, so compaction lands around 98k — close to the 101k point Paper Instruments' own harness uses.
No web search, and reading a PDF fails. Both are vendor limitations of this endpoint. Give the agent the text you want it to read rather than a PDF path.
Your whole session goes to Paper Instruments while it runs — prompts, every file the agent reads, and every tool result. Paper Instruments states it does not store customer content or train on it by default, and keeps operational metadata (token counts, request shape, latency). Disclosure row: SUBPROCESSORS.md #100.

If something goes wrong

What you see	What it means
"Key missing" when starting a session	The key field is empty, or the spawn toggle is off — both live on the provider card.
`401 invalid_api_key`	The key was revoked or belongs to another environment; create a new one.
`429 insufficient_quota`	The account balance is empty — add funds.
`429 rate_limit_exceeded`	The organisation's rate or concurrency limit was hit; wait for `retry-after`.
`404 model_not_found`	A model other than `ultramarine-1-flash` was requested.

Code references

src/shared/providers/provider-setup-catalog.ts — the endpoint, model-list URL and console link.
src/main/services/anthropic-compat-provider.ts — base URL, key access, model-alias pins, the beta-disable flag and the effort clamp.
src/shared/providers/registry.ts — the engine's declared capabilities and picker slot.
src/shared/providers/supply-list.ts — USER_KEY_ONLY_SUPPLY_FAMILIES, the declaration that this vendor has no Omniscio credit lane.
src/shared/model-pricing.ts, src/shared/types/context-window.ts — the published rates and window.