/**
 * Model pricing catalog — USD per 1k tokens, snapshot-dated per entry.
 *
 * Used by:
 * - `@gemstack/ai-sdk/eval` to populate the cost column on eval reports
 * - `@gemstack/ai-sdk`'s budget enforcement middleware (A6 phase 3) to debit
 *   per-user spend against caps
 *
 * # Pricing drift
 *
 * Provider list pricing changes monthly. Each entry carries `_snapshotDate`
 * indicating when the rate was captured. Apps with negotiated rates should
 * pass an override map:
 *
 * ```ts
 * import { ModelPricing, withBudget } from '@gemstack/ai-sdk'
 *
 * withBudget({
 *   pricing: {
 *     ...ModelPricing,
 *     'anthropic/claude-opus-4-7': {
 *       inputPer1k:  0.012,
 *       outputPer1k: 0.060,
 *       _snapshotDate: '2026-01-15',
 *     },
 *   },
 *   // ...
 * })
 * ```
 *
 * # Cache rates
 *
 * Anthropic, OpenAI, and Google all offer reduced rates for cache reads
 * (and Anthropic charges a small premium for cache writes). The optional
 * `cacheReadPer1k` / `cacheWritePer1k` fields capture those. The budget
 * middleware uses them when `TokenUsage` carries cache deltas; when absent
 * (today's `TokenUsage` shape), input rate applies to all input tokens.
 */
/** Pricing for a single `<provider>/<model>` id, USD per 1k tokens. */
export interface ModelPriceEntry {
    /** Cost per 1k input (prompt) tokens, USD. */
    inputPer1k: number;
    /** Cost per 1k output (completion) tokens, USD. */
    outputPer1k: number;
    /**
     * Optional cost per 1k cached-read input tokens, USD. Set when the
     * provider exposes a discounted rate for cache hits (Anthropic ephemeral
     * cache, OpenAI prefix cache, Google cachedContent). When omitted,
     * `inputPer1k` applies to all input tokens.
     */
    cacheReadPer1k?: number;
    /**
     * Optional cost per 1k cache-write input tokens, USD. Anthropic charges
     * a small premium on the first write that primes an ephemeral cache;
     * other providers don't. When omitted, `inputPer1k` applies.
     */
    cacheWritePer1k?: number;
    /**
     * ISO date string indicating when this rate was captured from the
     * provider's published pricing. Surfaced in
     * {@link UnknownModelPricingError} messages and useful when auditing
     * stale catalogs.
     */
    _snapshotDate: string;
}
/**
 * `<provider>/<model>` → {@link ModelPriceEntry}. Override entries by
 * spreading: `{ ...ModelPricing, 'anthropic/claude-opus-4-7': {...} }`.
 *
 * Snapshot date: 2026-05-11.
 */
export declare const ModelPricing: Record<string, ModelPriceEntry>;
/**
 * Compute USD cost for an agent call given prompt + completion token
 * counts and a pricing catalog.
 *
 * Returns `0` when the model id isn't in `pricing` — eval cost columns
 * shouldn't crash on a fresh model. The budget middleware (A6 phase 3)
 * uses {@link assertKnownModelPricing} to fail loud at config time
 * instead.
 *
 * @param model     `<provider>/<model>` id
 * @param promptTokens  Input tokens charged at `inputPer1k`
 * @param completionTokens  Output tokens charged at `outputPer1k`
 * @param pricing   Catalog override (defaults to {@link ModelPricing})
 */
export declare function estimateCost(model: string, promptTokens: number, completionTokens: number, pricing?: Record<string, ModelPriceEntry>): number;
/**
 * Budget enforcement uses this — fail loud at agent-construction time
 * if the configured model isn't priced. Call from `withBudget(...)` in
 * phase 3.
 *
 * @throws {UnknownModelPricingError} when `pricing[model]` is missing
 */
export declare function assertKnownModelPricing(model: string, pricing?: Record<string, ModelPriceEntry>): ModelPriceEntry;
/**
 * Thrown by `assertKnownModelPricing` when a model id has no pricing
 * entry. The budget middleware throws this at construction so apps
 * fail at boot, not on first prompt.
 */
export declare class UnknownModelPricingError extends Error {
    readonly model: string;
    readonly snapshotDate: string | null;
    constructor(model: string, pricing: Record<string, ModelPriceEntry>);
}
/**
 * Thrown by the budget middleware (A6 phase 3) when a request would
 * exceed a user's daily or monthly cap. Apps that want a different
 * error type can intercept via `withBudget({ onExceeded })` and throw
 * their own.
 */
export declare class BudgetExceededError extends Error {
    readonly userId: string;
    readonly period: 'daily' | 'monthly';
    readonly spent: number;
    readonly cap: number;
    constructor(opts: {
        userId: string;
        period: 'daily' | 'monthly';
        spent: number;
        cap: number;
    });
}
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