/**
 * Retention-structure auditor.
 *
 * Long-form videos live or die at the 3-min and 6-min marks. Per the
 * MrBeast manual: every ~3 minutes a "mini-hook" / re-engagement is
 * required — a twist, a reveal, a visual spectacle, an escalation. Flat
 * stretches between mini-hooks bleed retention; the YouTube graph
 * shows the dip almost every time.
 *
 * This module:
 *   1. Builds a 60s window centred on each requested checkpoint.
 *   2. Bundles all windows + a compact transcript outline into ONE LLM call.
 *   3. Parses the response into a structured report with per-checkpoint
 *      scores + an overall escalation pattern score.
 *
 * Pure parser + window-builder for unit tests; the network call lives
 * here too but is exported as `runRetentionAudit` so the wrapper tool
 * stays thin.
 */
import type { Transcript } from "./whisper.js";
export interface RetentionWindow {
    /** Centre of the window. */
    atSec: number;
    /** Inclusive [startSec, endSec]. */
    startSec: number;
    endSec: number;
    /** Concatenated transcript text falling inside the window. */
    text: string;
}
export interface CheckpointScore {
    atSec: number;
    /** 0-1. ≥0.5 = re-engagement detected. <0.5 = flat / weak. */
    score: number;
    /** ≤120 char description of what's happening at this checkpoint. */
    summary: string;
    /** ≤200 char actionable suggestion when score < 0.5. Empty otherwise. */
    suggestion: string;
}
export interface RetentionAuditResult {
    checkpoints: CheckpointScore[];
    /** 0-1. Does the video build progressively (1) or stay flat (0)? */
    escalationScore: number;
    /** ≤200 char overall verdict. */
    overallSummary: string;
    /** atSec of the lowest-scoring checkpoint (-1 when checkpoints is empty). */
    weakestCheckpoint: number;
}
/**
 * Build a 60s window centred on `atSec`, clamped to [0, totalSec].
 * Returns the concatenated transcript text inside the window for LLM
 * context. Pure — exported for testing.
 */
export declare function buildWindow(t: Transcript, atSec: number, totalSec: number, windowSec?: number): RetentionWindow;
/**
 * Compact transcript outline — every Nth segment trimmed to ~60 chars
 * with a leading [t]s tag. Keeps the LLM grounded in overall pacing
 * without blowing the context budget on a long transcript.
 */
export declare function buildOutline(t: Transcript, maxLines?: number): string;
export interface RetentionAuditOptions {
    apiKey?: string;
    model?: string;
    /** Default [180, 360] (3min, 6min). */
    checkpoints?: number[];
    /** Override transcript.durationSec (e.g. when you trust ffprobe more). */
    durationSec?: number;
    signal?: AbortSignal;
}
/**
 * Run ONE LLM audit pass and return the structured result. Throws on
 * network / parse error so the wrapper can convert to err().
 */
export declare function runRetentionAudit(t: Transcript, opts?: RetentionAuditOptions): Promise<RetentionAuditResult>;
/**
 * Parse the model's JSON. Robust to missing keys; pads checkpoints to
 * match the requested order so the caller can correlate by index.
 *
 * Pure — exported for testing.
 */
export declare function parseAuditResponse(content: string, requested: number[]): RetentionAuditResult;
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