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# Cost and reproducibility

## Cost and reproducibility

A forecasting engine that you pay for, and trust, has to be honest about two things: what a run cost, and what it actually did. NFA is built so both are verifiable rather than taken on faith.

### Per-purpose model routing

Different parts of a run have different needs. The ruling deserves a strong model; lighter steps can run on cheaper ones. NFA routes each step to an appropriate model rather than using one model for everything, which keeps quality where it matters and cost down where it does not. The verification step deliberately uses a separate, independent model from the judge, so a forecast is never checked by the same reasoning that produced it.

### Honest cost accounting

Every model call is metered in USD as it happens. Those totals are reconciled against the provider's own billing records to a small tolerance, so the cost attributed to a run is the real cost, not an estimate. Repeated context within a run is cached to cut both latency and spend.

{% hint style="info" %}
This is why run pricing can be tied to actual usage rather than a flat guess. See [Credits](/nfa-docs/the-economy/credits.md) for how compute cost becomes a credit price.
{% endhint %}

### Reproducibility and audit

Every run records what it did: which models ran, which options were active, what data anchored it, and what the self-verification concluded. Combined with deterministic data routing, where the same market always resolves to the same source and value, this makes a forecast reconstructable after the fact. You are never asked to trust a number with no provenance; the provenance is part of the record.


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