wehub-resource-sync
32 lines
1.3 KiB
TypeScript
32 lines
1.3 KiB
TypeScript
import type { ContextBudgetConfig, ContextBudgetPolicy } from "./types.ts";
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/**
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* Pure target-token computation (design D-C1). No clock, no DB, no tokenizer.
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*
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* @param policy active target policy
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* @param modelContextLimit the resolved upstream model's context window (impure caller looks it up)
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* @param requestMaxTokens request.max_tokens, if the client sent one (reserve-output only)
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* @param config reserves / margin / pct / absoluteBudget
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* @returns the maximum prompt-token target the compressed request should fit within
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*/
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export function computeTarget(
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policy: ContextBudgetPolicy,
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modelContextLimit: number,
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requestMaxTokens: number | null,
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config: Pick<ContextBudgetConfig, "outputReserve" | "safetyMargin" | "pct" | "absoluteBudget">
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): number {
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if (policy === "absolute") {
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return Math.max(0, Math.floor(config.absoluteBudget));
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}
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if (policy === "percentage") {
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const pct = config.pct > 0 && config.pct <= 1 ? config.pct : 1;
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return Math.max(0, Math.floor(modelContextLimit * pct));
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}
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// reserve-output (default): limit − output reservation − safety margin.
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const reserve =
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typeof requestMaxTokens === "number" && requestMaxTokens > 0
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? requestMaxTokens
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: config.outputReserve;
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return Math.max(0, Math.floor(modelContextLimit - reserve - config.safetyMargin));
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}
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