/**
 * Backend validator — shared by `log10x_configure_env` (validate
 * before persisting) and `log10x_doctor` (validate periodically).
 *
 * Probes the metrics backend in four steps, surfacing the first
 * failure with a clear, actionable diagnostic. The four checks are:
 *
 *   1. **Reachable** — TCP connect + HTTP request returns any
 *      response. Fails on DNS, connection refused, TLS handshake
 *      failure, timeout.
 *   2. **Authenticated** — `up` query returns 200 + `status:success`.
 *      Fails on 401/403 (bad auth), 429 (rate limit), 5xx (backend
 *      down). Distinguishes "wrong creds" from "wrong URL".
 *   3. **Engine metrics present** — `count(all_events_summaryBytes_total)`
 *      returns a non-empty / non-zero result. Catches the
 *      read/write URL mismatch: backend is reachable but the 10x
 *      engine isn't writing to it.
 *   4. **Expected labels present** — the metric carries the labels
 *      the env's `labels` map expects (default: `message_pattern`,
 *      `tenx_user_service`, `severity_level`, `tenx_env`). Catches
 *      the rename mismatch — engine renamed labels but the env's
 *      `labels` override wasn't updated to match.
 *
 * Returns a structured result; never throws. Callers render it as
 * markdown.
 */
import type { MetricsBackend } from './metrics-backend.js';
import type { LabelNameMap } from './promql.js';
export type CheckStatus = 'pass' | 'fail';
export interface CheckResult {
    name: string;
    status: CheckStatus;
    detail: string;
    /** Optional remediation hint shown when status is `fail`. */
    hint?: string;
}
export interface ValidationResult {
    /** True iff every check passed. */
    ok: boolean;
    /** Ordered list of check results — first failure aborts the chain. */
    checks: CheckResult[];
}
/**
 * Run the four-step probe against a backend. Stops on the first
 * failure so the user sees the FIRST problem to fix (not a noisy
 * cascade).
 */
export declare function validateBackend(backend: MetricsBackend, labels: LabelNameMap): Promise<ValidationResult>;
/**
 * Render a ValidationResult as markdown for tool output. Used by both
 * configure_env (when validation fails) and doctor (in the per-env
 * status section).
 */
export declare function renderValidationResult(result: ValidationResult, env: {
    nickname: string;
    metricsBackend: MetricsBackend;
}): string;