import type { ChatMessage } from "../types.js";
/**
 * Marker prefix used when a mid-conversation `system` message has to be
 * delivered as a user turn because the provider dialect only has a single
 * top-level system field (Anthropic `system`, Gemini `systemInstruction`).
 */
export declare const SYSTEM_TURN_MARKER = "[SYSTEM]";
/** Mutable, current-turn authority promoted into provider system fields. */
export declare const REQUEST_CONTEXT_PREFIX = "REQUEST CONTEXT";
export declare function isRequestContextSystemMessage(message: ChatMessage): boolean;
export declare function requestContextSystemPrompts(messages: readonly ChatMessage[]): string[];
export declare function withoutRequestContextSystemMessages(messages: readonly ChatMessage[]): ChatMessage[];
export declare function upsertRequestContextMessage(messages: ChatMessage[], content: string): void;
/**
 * One shared ordered normalization contract for dialects with a
 * single system slot.
 *
 * The first system message becomes the dialect's system field. Every later
 * system message (compaction memory, live plan, engagement scope, Responder
 * ledger, loop-guard/progress steering) is preserved *in place* as a user turn
 * tagged with {@link SYSTEM_TURN_MARKER}, so ordering relative to tool groups
 * is untouched and nothing is silently dropped.
 *
 * The marker is applied exactly once: content that already carries it is
 * passed through unchanged.
 */
export declare function normalizeSystemMessages(messages: ChatMessage[]): {
    /** Content of the first system message, if any. */
    systemPrompt: string | undefined;
    /** History with later system messages converted to marked user turns. */
    rest: ChatMessage[];
};
export declare function singleLeadingSystemMessages(messages: readonly ChatMessage[]): ChatMessage[];
export declare function markSystemTurn(content: string): string;
/** Content of the first system message, matching the dialect system field. */
export declare function firstSystemPrompt(messages: ChatMessage[]): string | undefined;