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Tiny model. Big decisions. — How I built a 144M-parameter typed decision model that routes 82% of agent decisions off LLMs

A developer built Phocinae-Largha-150M-v1, a 144.3M-parameter typed decision model that answers yes/no, pick-one and 1-10 questions in a single forward pass at 18.6 ms p50 on GPU, scoring 0.797 on English typed-decisions (400 cases / 2,000 decisions) versus published same-protocol scores of 0.766 for Laya, 0.768 for meraGPT and 0.727 for JEV-27B. With a τ=0.6 confidence gate that escalates uncertain cases to a larger LLM, the Chinese route cut LLM calls by 82% (100% to 18%) while combined accuracy rose from 0.789 to 0.7948. The Apache-2.0 model is served locally over a /v1/systemone protocol with calibrated probabilities, alongside an npm DeepSeek Harness bundle with a fail-closed PreToolUse approval gate.

by read3 min views3 publishedOct 8, 2026

Or: why your agent's "should I run this command?" does not need a 70B chat model.

Every agentic workflow I build hits the same wall: the interesting logic is 10 lines, and the other 90% is a language model deciding "allow or deny?", "which tool?", "pass or escalate?" — thousands of times a day, at chat-model prices and chat-model latency.

So I built the opposite of a chatbot: Phocinae-Largha-150M-v1, a 144.3M-parameter typed decision model. It cannot generate text. It takes a state plus a list of typed questions (yes/no, pick-one, 1-10 score) and returns, in one forward pass, a verdict per question with calibrated confidence. GPU: 18.6 ms p50 per decision. CPU-only: ~1.5 s, no GPU at all. Open-source, Apache-2.0.

A decision is a typed output over a closed option set:

state: "agent wants to run: rm -rf /var/log/app"
question: { type: noul, qid: allow, options: [false, true] }
answer:  { allow: { label: false, prob: 0.96, confidence: 0.96 } }

There is no sentence to generate, no chain-of-thought to emit, no format to parse back. So why rent a generative model for it? A 150M encoder (mmBERT-small base, 256k vocab, Gemma tokenizer) does one forward pass and outputs label logits per question — that is the entire inference. Deterministic: same input, same output. No sampling, no parsing failures.

The evaluation protocol is typed-decisions (the format used by Laya and others), which makes scores directly comparable across models on the same rows.

English typed-decisions: 0.797 (400 cases / 2,000 decisions). Chinese (machine-translated eval set, no native zh training rows — disclosed): 0.789. Same-protocol published scores: Laya 0.766 · JEV-27B 0.727 · meraGPT 0.768.

The metrics most model cards skip, we publish:

A small model does not need to be perfect — it needs to know when it is not. With a τ=0.6 confidence gate, confident decisions stay local and the rest escalate to a bigger model. Result on the zh route: LLM calls cut 82% (100% → 18%), while combined accuracy went 0.789 → 0.7948 — routing the hard 18% upward made the whole system slightly better, not just cheaper.

That is the framing I want to leave with you: System 1 in BERT. The two-system picture for agents is not "small model vs big model" — it is typed, deterministic, milliseconds, free for the repetitive 82%, and generative, expensive only for the ambiguous 18%.

pip install phocinae-server huggingface_hub
huggingface-cli download Phocinae/Phocinae-Largha-150M-v1 --local-dir ./model
PHOC_MODEL_DIR=./model python -m phocinae.main
curl -s http://127.0.0.1:8155/v1/systemone \
  -H 'Content-Type: application/json' \
  -d '{"state":"The agent wants to run: rm -rf /var/log/app",
       "questions":[{"type":"noul","qid":"allow",
                     "question":"Allow this command?","options":["false","true"]}]}'

The server is local-only (127.0.0.1), pure PyTorch at runtime, and the protocol (/v1/systemone: noul / choice / score questions, calibrated probabilities) is fully specified in the repo. There is also a DeepSeek Harness bundle (dsh-phocinae, npm) with a PreToolUse approval gate that fails closed.

If you have a use case that is mostly repetitive decisions, I'd love to hear what breaks first.

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