@sema-agent/core/dist/core/select-model.js

Stateless, task-oriented AI agent core

function asList(models) {
    return Array.isArray(models) ? models : Object.values(models);
}
function costOf(m) {
    if (!m.cost) {
        return Number.POSITIVE_INFINITY;
    }
    return (m.cost.input ?? 0) + (m.cost.output ?? 0);
}
function matches(m, c) {
    for (const need of c.needs ?? []) {
        if (need === "vision" && !m.input?.includes("image"))
            return false;
        if (need === "reasoning" && !m.reasoning)
            return false;
    }
    if (c.minContext != null && (m.contextTokens ?? m.contextWindow ?? 0) < c.minContext) {
        return false;
    }
    if (c.tier != null && m.params?.tier !== c.tier) {
        return false;
    }
    return true;
}
export function selectModel(models, criteria = {}) {
    const candidates = asList(models).filter((m) => matches(m, criteria));
    if (candidates.length === 0) {
        return undefined;
    }
    const premium = criteria.prefer === "premium";
    return candidates.reduce((best, m) => {
        const c = costOf(m);
        const b = costOf(best);
        return premium ? (c > b ? m : best) : c < b ? m : best;
    });
}
export function selectModelOrThrow(models, criteria = {}) {
    const m = selectModel(models, criteria);
    if (!m) {
        throw new Error(`selectModel: no model in the catalog matches ${JSON.stringify(criteria)}`);
    }
    return m;
}