import type { JsonObject, Message, ProviderRequest, ProviderRequestOptions, Usage } from "@arnilo/prism";
/** OpenRouter `session_id` / `x-session-id` documented max length. */
export declare const OPENROUTER_SESSION_ID_MAX_LENGTH = 256;
export declare function openRouterSessionId(options: ProviderRequestOptions | undefined): string | undefined;
/**
 * Whether OpenRouter cache_control markers may be emitted for this request.
 * Caching is enabled when not explicitly disabled (`cacheRetention !== "none"`,
 * `cache.mode !== "off"`) and the model opts in via `ModelCacheCapabilities`
 * (`kind: "cache_control"`) or the legacy `compat.openRouterCache` flag.
 */
export declare function openRouterCacheEnabled(request: ProviderRequest): boolean;
/**
 * Apply Anthropic-style `cache_control` only to the requested Prism breakpoints,
 * not to every content block. Returns the Prism messages with markers on the
 * last content block of each selected message; the OpenRouter message converter
 * preserves those markers. With no breakpoints, no markers are emitted and
 * OpenRouter's implicit caching (when available) handles prefix reuse.
 */
export declare function applyOpenRouterCacheControl(request: ProviderRequest): readonly Message[];
/**
 * Official OpenRouter automatic Anthropic-style caching: a single top-level
 * `cache_control` when caching is enabled and the host did not select explicit
 * breakpoints. Prefer breakpoints for fine-grained control.
 * @see https://openrouter.ai/docs/guides/best-practices/prompt-caching
 */
export declare function openRouterTopLevelCacheControl(request: ProviderRequest): JsonObject | undefined;
/**
 * Preserve a `cache_control` marker carried on a Prism content block when
 * converting to the OpenRouter content shape. Marker only lands on the last
 * block of a breakpoint-selected message (set by `applyOpenRouterCacheControl`).
 */
export declare function withOpenRouterCacheMarker(contentItem: JsonObject, marker: JsonObject | undefined): JsonObject;
export declare function openRouterUsage(usage: OpenRouterUsage | undefined): Usage | undefined;
export interface OpenRouterUsage {
    readonly prompt_tokens?: number;
    readonly completion_tokens?: number;
    readonly total_tokens?: number;
    readonly prompt_tokens_details?: {
        readonly cached_tokens?: number;
        readonly cache_write_tokens?: number;
    };
}