Klix

Decoupled decision heads on a shared semantic backbone. A text passes through the embedding model exactly once (dense + sparse), after which any number of heads (Choice, Score, Flag) operate on the precomputed vectors — each in its own mathematical space. No model training, no slot limits, fully offline and CPU-only.

Architecture

Text ──► HybridBackbone (FastEmbed dense + TF-IDF sparse, once, ~10 ms)
              │
              ├──► Choice   (routing/classification: max-similarity + keyword boost)
              ├──► Score    (continuous axis: low/high anchors + sigmoid)
              ├──► Flag     (boolean: 2/3-class softmax with temperature)
              └──► custom heads (subclass BaseHead)

• Shared backbone: Each text is embedded and TF-IDF-transformed exactly once. Whether you register 3 heads or 50, the extraction cost stays the same.
• Decoupled heads: Adding options to one Choice never affects Score or Flag results. Every head encapsulates its own logic.
• Declarative: Define schemas with example sentences, call compile(), done.
• Honest uncertainty: Optional reject poles (Choice(reject_anchors=...), Flag(neutral_anchors=...)) return None instead of guessing; the Score head reports a coverage signal so you know when a score is noise.
• Language-agnostic anchors: The backbone model is multilingual, so anchor sentences in any language work — German, English, mixed, whatever fits your domain.

Installation

uv add klix-engine
# or
pip install klix-engine

On first use, FastEmbed downloads the paraphrase-multilingual-MiniLM-L12-v2 model (~120 MB, one-time, then cached locally). Everything runs offline afterwards.

Quickstart

from klix import DecisionEngine, Choice, Score, Flag

engine = DecisionEngine()

engine.add_head(
    Choice(
        name="target",
        options={
            "it_ops": ["VPN down", "server unreachable", "laptop won't boot"],
            "ot_plant": ["robot cell stopped", "PLC fault", "plc-34 error", "cycle time deviation"],
            "finance": ["cost center over budget", "approve invoice"],
            "facility": ["oil spill in hall 2", "heating broken"],
        },
        # Optional: texts resembling these get value=None instead of a forced guess.
        reject_anchors=["casual office chat", "birthday wishes", "off topic request"],
    )
)

engine.add_head(
    Score(
        name="urgency",
        low_anchors=["routine maintenance", "casual question"],
        high_anchors=["emergency right now", "production line down", "acute danger"],
        min_val=0.0,
        max_val=3.0,
        # "topk" pools the best 2 anchors per pole (robust against a single
        # noisy anchor). Every result carries "coverage": if it is low (< ~0.3),
        # the text matched neither pole and the score is mostly noise.
        aggregation="topk",
    )
)

engine.add_head(
    Flag(
        name="is_security",
        true_anchors=["hacker attack", "ransomware infection", "data exfiltration"],
        false_anchors=["hardware broken", "ordinary IT problem", "network outage"],
        # Optional third pole: when "neutral" wins, value=None instead of True/False.
        neutral_anchors=["routine request", "general question", "other topic"],
        threshold=0.5,
    )
)

engine.compile()

res = engine.decide("plc-34 reports a fault, conveyor belt stopped immediately!")

print(res)                                   # e.g. <DecisionResult (11 ms): target=ot_plant, urgency=2.4, is_security=False>
print(res.target)                            # 'ot_plant'
print(res.urgency)                           # continuous score between 0.0 and 3.0
print(res.is_security)                       # True / False / None (neutral won)
print(res.details("is_security"))            # full dict: value, probability, probabilities

Exact score values depend on your anchors — always treat the outputs as calibrated signals, not ground truth, and tune the anchors to your domain.

Configuration

Every head and the engine expose meaningful knobs:

Custom Heads

Subclass BaseHead and implement evaluate(encoded):

import re
from klix import BaseHead

class RegExExtractionHead(BaseHead):
    def __init__(self, name: str, pattern: str):
        super().__init__(name)
        self.re = re.compile(pattern)

    def get_reference_texts(self) -> list[str]:
        return []  # no reference texts needed

    def fit(self, backbone) -> None:
        pass

    def evaluate(self, encoded) -> dict:
        match = self.re.search(encoded.text)
        return {"value": match.group(0) if match else None}

Benchmarks

All benchmarks are reproducible — scripts live in evals/ and every method is trained/evaluated on the same labeled data (the anchors are the few-shot training set).

Bilingual routing (EN/DE, 5 classes, support tickets)

evals/benchmark_bilingual.py — 10 English + 10 German test cases with parallel meaning, anchors mixed EN/DE. Reproduce with:

uv run python -c "import sys; sys.path.insert(0,'.'); sys.path.insert(0,'src'); from evals import benchmark_bilingual; benchmark_bilingual.main()"

Latency per decision (CPU, includes the ~10 ms embedding forward pass): all embedding-based methods ≈ 9–13 ms; TF-IDF+LogReg ≈ 0.9 ms (no embeddings).

Reading this honestly: on this mixed-language, few-anchor schema the linear probe overfits to English (100 % EN / 50 % DE). The dense Embed-KNN is the most language-robust. Recommendation: with few mixed-language anchors, use classifier="nearest"; the linear probe pays off on single-language schemas with several anchors per class (see the cross-domain result below).

Cross-domain routing (6 domains, 70 cases, mostly EN)

evals/benchmark.py — HR, Finance, Image-captions, Tasks, Shop, and the LLM-guardrail scenario:

Here klix linear is the clear accuracy winner (+8 pts over the nearest-anchor ceiling), at a still-CPU-friendly ~13 ms.

vs. Laya (convaiinnovations/laya)

Klix's original inspiration is the trained zero-shot engine laya (Torch/ModernBERT-large, GPU-oriented). Measured on the same 70 cases on CPU:

The honest trade-off: Laya needs no examples and natively routes 100+ languages with automatic script detection — a real advantage for low-resource scripts on GPU. Klix is the opposite design point: a tiny model, few-shot anchors you fully control, and 100× lower CPU latency. They are complements, not substitutes.

Choosing a variant

• classifier="nearest" (default) — most robust with few or mixed-language anchors; always a safe baseline.
• classifier="linear" — highest accuracy on single-language schemas with 3+ anchors per class; watch for overfitting with mixed-language few-shot data.
• label_aggregation="topk" — damps single-anchor noise when you have 4+ anchors per label.

Development

uv sync          # install dependencies
uv run pytest    # run tests (50 tests, fully offline)
uv run python examples/demo.py

The evals/ directory contains a labeled evaluation harness (routing accuracy, score bands, flag behavior, out-of-domain rejection) — use it to measure changes to your anchor schemas.

Release chain (automated): bump the version in pyproject.toml and __init__.py, commit, tag, push — GitHub Actions builds and publishes to PyPI automatically (workflow publish.yml, secret PYPI_TOKEN):

git tag vX.Y.Z
git push origin main vX.Y.Z

License

MIT