/**
 * [WHO]: Provides DiagnosticEvent types, reportDiagnostic(), subscribeDiagnostics(), isDevRuntime()
 * [FROM]: Depends only on node:events and node built-ins
 * [TO]: Imported by repo-root code (extensions/, core/, modes/) for unified background-failure reporting; mirrored by tiny shells in standalone packages (e.g. packages/mem-core/src/diagnostics.ts) that share the same Symbol.for slot at runtime
 * [HERE]: utils/diagnostics.ts - canonical diagnostic bus; explicit dev/debug mode prints to console, every mode emits to the in-process bus where the diagnostics extension subscribes and auto-uploads
 *
 * Cross-compile-boundary sharing: independent packages compile their own copy of
 * a thin shell, but every copy resolves the same `Symbol.for(...)` slot on
 * globalThis at runtime, so all reportDiagnostic() calls flow through one bus.
 */
export type DiagnosticSeverity = "debug" | "info" | "warning" | "error";
export type DiagnosticCategory = "network" | "fallback" | "persistence" | "config" | "extension_timeout" | "schema" | "unknown";
export interface DiagnosticEvent {
    source: string;
    severity: DiagnosticSeverity;
    category: DiagnosticCategory;
    message: string;
    detail?: unknown;
    fingerprint?: string;
    context?: Record<string, unknown>;
}
/**
 * Unified dev-mode predicate. True only for explicit developer intent:
 * - NODE_ENV=development, OR
 * - npm_lifecycle_event is "dev" or "test", OR
 * - CATUI_DEBUG is truthy (legacy NANOPENCIL_DEBUG is also accepted).
 *
 * Always false when NODE_ENV=production.
 */
export declare function isDevRuntime(): boolean;
export declare function reportDiagnostic(event: DiagnosticEvent): void;
/**
 * Subscribe to all diagnostic events, including those queued before the first
 * subscriber attached. Returns an unsubscribe function. Typically called once
 * by the diagnostics extension on load.
 */
export declare function subscribeDiagnostics(handler: (event: DiagnosticEvent) => void): () => void;