/**
 * Prompt cost as OpenTelemetry metrics, in the OTLP/HTTP JSON encoding.
 *
 * **Trazum writes the payload; it does not send it.** That is a decision, not a
 * missing feature. Pushing to a collector would mean holding an endpoint and a
 * credential, and this repository has twice shipped an SSRF where a URL reached
 * `fetch` without being the URL that was checked. A command that writes a file
 * has no such failure mode, and `curl --data-binary @metrics.json $OTLP_ENDPOINT`
 * is one line in the pipeline that already has the credential.
 *
 * No dependency on `@opentelemetry/*` either — the JSON encoding is a stable,
 * documented wire format, and this package has no runtime dependencies by design.
 *
 * The two encoding rules that are easy to get wrong and silently produce a
 * payload a collector drops:
 *
 * - **64-bit integers are strings.** `timeUnixNano` and `asInt` are `int64` in
 *   the protobuf, and JSON numbers cannot hold one exactly, so the JSON mapping
 *   specifies strings. A collector reading `1786000000000000000` as a double
 *   loses the last digits of every timestamp.
 * - **A gauge is `asDouble` or `asInt`, never both**, and a money figure is a
 *   double. Sending `asInt` for `$41.20` silently reports `41`.
 */
/** Attributes as OTLP encodes them: a list of key/value, not an object. */
export interface OtlpAttribute {
    key: string;
    value: {
        stringValue: string;
    } | {
        intValue: string;
    } | {
        doubleValue: number;
    };
}
export interface OtlpDataPoint {
    attributes: OtlpAttribute[];
    timeUnixNano: string;
    asInt?: string;
    asDouble?: number;
}
export interface OtlpMetric {
    name: string;
    description: string;
    unit: string;
    gauge: {
        dataPoints: OtlpDataPoint[];
    };
}
export interface OtlpPayload {
    resourceMetrics: [
        {
            resource: {
                attributes: OtlpAttribute[];
            };
            scopeMetrics: [{
                scope: {
                    name: string;
                    version: string;
                };
                metrics: OtlpMetric[];
            }];
        }
    ];
}
/** What `doctor` knows, in the shape this module needs. */
export interface OtlpInput {
    /** Every prompt surveyed, with the count a budget would be compared against. */
    prompts: readonly {
        path: string;
        tokens: number;
        overBudget: boolean;
        budgeted: boolean;
    }[];
    /** Advisories rolled up by id, as the survey reports them. */
    findings: readonly {
        id: string;
        prompts: number;
        monthlyUsd: number | null;
    }[];
    model: string;
    callsPerMonth: number;
}
/**
 * `atMillis` is a parameter rather than a call to `Date.now()`.
 *
 * The same reason `computeSavings` takes a `Date`: a function that reads the
 * clock cannot be asserted against a fixed expectation, and every test of it
 * ends up asserting only its shape. Here the timestamp *is* half the payload.
 */
export declare function toOtlpMetrics(input: OtlpInput, atMillis: number): OtlpPayload;
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