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System-1 Gateway

The System-1 Gateway gives Claude Code fast multiple-choice decisions from a small local engine, through one MCP server with three stable tools. You pick the engine (Laya, Von, Liquid AI d1 through llama.cpp, any Ollama chat model, a Hugging Face reranker through a small local server, a hosted Claude model, or one you add), and Claude sees the same tools whichever one answers. Python 3.11 or later and the standard library only; version 0.2.0, released 2026-10-20.

In Claude Code, three commands install it:

/plugin marketplace add TheMattHub/Sys1-AI-Gateway
/plugin install system1@system1-gateway
/system1:setup

After a restart Claude can ask it a judgement call. One system1_decide call and its answer, here from the built-in mock provider (latencies set to 0):

{"question": "Rerun the flaky pipeline or block the merge?",
 "options": ["rerun the pipeline", "block the merge"]}

{"schema_version": "1", "request_id": "demo-1", "status": "decided",
 "decision": "rerun the pipeline", "confidence": 0.9,
 "rationale": "mock provider: always picks the first option", "provider": "mock",
 "probabilities": {"rerun the pipeline": 0.9, "block the merge": 0.09999999999999998},
 "calibrated": false, "latency_ms": 0,
 "attempts": [{"provider": "mock", "outcome": "ok", "latency_ms": 0, "detail": null}], "error": null}

Three things set it apart. It abstains instead of guessing: below the confidence threshold the answer is abstained and Claude reasons it through itself. The threshold means something, because each engine's probabilities are calibrated on labelled decisions. And the choice of engine rests on measurement: the naga decisions study compares every engine we tried on frozen blind test sets.

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