import type { LanguageModel, ModelMessage, SystemModelMessage, ToolSet } from "ai";
/**
 * The caching strategy to apply for one harness step.
 */
export type PromptCachePath = {
    readonly kind: "gateway-auto";
} | {
    readonly kind: "anthropic-direct";
} | {
    readonly kind: "none";
};
/**
 * Cache marker injected on the Anthropic-direct path.
 *
 * The AI SDK Anthropic provider reads `providerOptions.anthropic.cacheControl`
 * from message, message-part, system-message, and tool objects. The same
 * namespace is used by `@ai-sdk/amazon-bedrock/anthropic` and
 * `@ai-sdk/google-vertex/anthropic`, which both implement the native
 * Anthropic Messages API.
 */
export interface AnthropicCacheMarker {
    readonly anthropic: {
        readonly cacheControl: {
            readonly type: "ephemeral";
        };
    };
}
/**
 * Detects which prompt caching path applies to a resolved model.
 *
 * Runs once per harness step right after `resolveModel()`.
 */
export declare function detectPromptCachePath(model: LanguageModel): PromptCachePath;
/**
 * Returns the shared Anthropic cache marker used on the `anthropic-direct`
 * path. Exposed for unit tests and for the harness wiring layer.
 */
export declare function getAnthropicCacheMarker(): AnthropicCacheMarker;
/**
 * Returns a new `providerOptions` object with
 * `gateway.caching = "auto"` merged into the existing `gateway` sub-object.
 *
 * Preserves any existing author-provided `gateway` keys (such as
 * `order: ["anthropic", "bedrock"]` load balancing), and leaves an
 * explicit author override on `gateway.caching` untouched so callers can
 * opt out by setting `providerOptions.gateway.caching` to `false` or
 * another value.
 */
export declare function mergeGatewayAutoCaching(base: Readonly<Record<string, unknown>> | undefined): Record<string, unknown>;
/**
 * Returns a new ToolSet where the last tool entry carries the Anthropic
 * cache marker on `providerOptions`. Used on the `anthropic-direct` path
 * to place a stable breakpoint at the end of the tools block, caching the
 * full tool definitions across every turn.
 *
 * No-op when `tools` has no entries. Preserves existing `providerOptions`
 * on tools (merges the cache marker in via spread).
 */
export declare function applyLastToolCacheBreakpoint(tools: ToolSet, marker: AnthropicCacheMarker): ToolSet;
/**
 * Marks the last system message in an instructions array with the Anthropic
 * cache marker. This creates a cache breakpoint at the end of the system
 * prompt, preserving the system prefix when tools change between steps.
 *
 * When `instructions` is a string or undefined, returns it unchanged —
 * single-string system prompts don't support per-message providerOptions.
 * No-op when the array is empty.
 */
export declare function applySystemCacheBreakpoint(instructions: readonly SystemModelMessage[], marker: AnthropicCacheMarker): SystemModelMessage[];
/**
 * Walks backward through `messages` and attaches the Anthropic cache marker
 * to the most recent `assistant` and most recent `user` message. Returns a
 * new array; does not mutate the input.
 *
 * This implements the "automatic cache advancement" pattern: each turn the
 * breakpoints move forward, and the prior turn's breakpoints still warm the
 * cache prefix, so the new breakpoints just extend the cached region.
 *
 * Tool-result messages (`role: "tool"`) are intentionally skipped — the
 * adjacent assistant message's cache marker already covers the prefix
 * through any preceding tool results.
 */
export declare function applyConversationCacheControl(messages: readonly ModelMessage[], marker: AnthropicCacheMarker): ModelMessage[];