import type { ClaudeCacheBreakpointOptions, ClaudeRequest, VertexAnthropicCacheInput, VertexAnthropicCacheOutput, VertexAnthropicMessage } from "../types/index.js";
/** Anthropic allows at most four `cache_control` breakpoints per request. */
export declare const ANTHROPIC_MAX_CACHE_BREAKPOINTS = 4;
/**
 * Annotate a native Vertex+Claude request with prompt-cache breakpoints.
 *
 * Budget allocation (max 4 markers):
 *   1. The stable prefix — the last system block when a system prompt is
 *      present (this single marker caches `tools + system`, since system
 *      renders after tools); otherwise the last tool definition.
 *   2-4. A rolling breakpoint on the last few messages, so the
 *      growing-but-now-stable conversation history is cached and only the
 *      newest turn is billed as fresh input.
 *
 * Pure: the inputs are cloned, never mutated.
 */
export declare function applyVertexAnthropicCacheBreakpoints(input: VertexAnthropicCacheInput): VertexAnthropicCacheOutput;
/**
 * Count the `cache_control` markers already present on a request. The direct
 * Anthropic path arrives with markers the upstream layers placed —
 * MessageBuilder tags the system prompt, the client tags the last tool
 * definition, and message content blocks may carry their own. Anthropic
 * rejects requests with more than four markers, so any additional history
 * breakpoints must fit in the remaining budget.
 */
export declare function countAnthropicCacheMarkers(input: {
    system?: string | ReadonlyArray<{
        cache_control?: unknown;
    }> | undefined;
    tools?: ReadonlyArray<{
        cache_control?: unknown;
    }> | undefined;
    messages: ReadonlyArray<VertexAnthropicMessage>;
}): number;
/**
 * Rolling history breakpoints for request paths whose stable-prefix markers
 * are managed upstream (direct Anthropic: system via MessageBuilder, last
 * tool via the provider client). Marks the last content block of up to `budget`
 * tail messages; a tail block that already carries a marker is left as-is
 * without consuming budget (it already serves as that breakpoint). Pure —
 * the input array is cloned, never mutated.
 */
export declare function applyAnthropicHistoryCacheBreakpoints(input: ReadonlyArray<VertexAnthropicMessage>, budget: number): VertexAnthropicMessage[];
/**
 * Breakpoint placement for a Claude Messages request the proxy built itself,
 * rather than one a client authored.
 *
 * A request translated from another wire format arrives with no markers at
 * all, because the format it came from has no way to express one: OpenAI-shaped
 * callers rely on automatic prefix caching, which Anthropic does not do. A
 * faithful translation is therefore cached at 0% on every turn, and a caller
 * that fell back here from an exhausted pool burns the replacement quota faster
 * than the one it was spared.
 *
 * Placement follows Anthropic's `tools → system → messages` rendering: one
 * marker on the last system block covers tools *and* system in a single
 * breakpoint, and the rest roll along the tail of the history so a growing
 * conversation keeps its settled prefix cached. Markers the caller supplied are
 * counted first and never displaced — this only spends what is left of the
 * four.
 *
 * Pure: inputs are cloned, never mutated.
 */
export declare function applyClaudeRequestCacheBreakpoints(request: ClaudeRequest, options?: ClaudeCacheBreakpointOptions): ClaudeRequest;