/**
 * Pure content utilities for the Hindsight backend.
 *
 * Ports the semantics of the upstream OpenCode plugin
 * (vectorize-io/hindsight @ hindsight-integrations/opencode/src/content.ts):
 *   - tag stripping for anti-feedback (a recalled <memories> block must
 *     never end up retained as a new memory)
 *   - recall query composition + truncation under a character budget
 *   - retention transcript framing
 */
export interface HindsightMessage {
    role: string;
    content: string;
}
export interface RecallResultLike {
    text: string;
    type?: string | null;
    mentioned_at?: string | null;
}
/**
 * Strip `<memories>`, `<mental_models>`, and legacy memory blocks.
 *
 * Both `<memories>` (per-turn recall) and `<mental_models>` (curated semantic
 * memory) are injected into the system prompt. If either leaks into the
 * retention transcript, every retain becomes a tighter feedback loop —
 * paraphrased memories feed the next consolidation, which feeds the next
 * mental-model refresh, which feeds the next retain. Always strip before
 * retaining.
 */
export declare function stripMemoryTags(content: string): string;
/** Format recall results into a bullet list for context injection. */
export declare function formatMemories(results: RecallResultLike[]): string;
/** Format current UTC time for the recall preamble. */
export declare function formatCurrentTime(now?: Date): string;
/**
 * Slice messages to the last N turns, where a turn boundary is a user message.
 * Returns the trailing tail starting at the (N-th from the end) user message.
 */
export declare function sliceLastTurnsByUserBoundary(messages: HindsightMessage[], turns: number): HindsightMessage[];
/**
 * Compose a recall query from the latest user prompt plus optional prior context.
 *
 * When `recallContextTurns <= 1` the query is just the trimmed latest prompt.
 * Otherwise we prepend a `Prior context:` block built from the trailing
 * `recallContextTurns` user-bounded turns (memory tags stripped, latest prompt
 * suppressed to avoid duplicating it inside the context block).
 */
export declare function composeRecallQuery(latestQuery: string, messages: HindsightMessage[], recallContextTurns: number): string;
/**
 * Truncate a composed recall query to `maxChars`.
 *
 * Always preserves the latest user message. Drops oldest context lines first
 * and degrades gracefully when even the latest message exceeds the budget.
 */
export declare function truncateRecallQuery(query: string, latestQuery: string, maxChars: number): string;
export interface RetentionTranscript {
    transcript: string | null;
    messageCount: number;
}
/**
 * Format messages into a retention transcript using `[role: ...]` markers.
 *
 * - When `retainFullWindow` is true, all messages are included (used when the
 *   caller pre-sliced the window itself).
 * - Otherwise, only the last user turn (last user message → end) is retained.
 *
 * Messages are tag-stripped before framing to break the recall→retain loop.
 * Returns `{ transcript: null }` when nothing meaningful survives.
 */
export declare function prepareRetentionTranscript(messages: HindsightMessage[], retainFullWindow?: boolean): RetentionTranscript;