/**
 * BRAIN Ingester — Tier-2 proposal candidate source.
 *
 * Queries brain.db for recurring-pain observations (citation_count >= 3,
 * last 7 days, quality_score >= 0.5) and returns ranked ProposalCandidate[].
 *
 * Design principles:
 * - NO LLM calls. All data comes from structured SQL queries.
 * - Title is template-generated: `[T2-BRAIN] Recurring issue: {title}`.
 *   This is the prompt-injection defence from T1008 §3.6.
 * - Failures are swallowed: returns empty array + pushes a non-fatal warning
 *   (`W_SENTIENT_INGESTER_DEGRADED`) into the active LAFS envelope (T9773).
 *   Brain.db absence must never crash the propose tick.
 *
 * @task T1008
 * @see ADR-054 — Sentient Loop Tier-2
 */
import type { DatabaseSync } from 'node:sqlite';
import type { ProposalCandidate } from '@cleocode/contracts';
/** Maximum candidates returned from a single brain ingester pass. */
export declare const BRAIN_INGESTER_LIMIT = 10;
/** Minimum citation count for a brain entry to be considered. */
export declare const BRAIN_MIN_CITATION_COUNT = 3;
/** Minimum quality score for a brain entry to be considered. */
export declare const BRAIN_MIN_QUALITY_SCORE = 0.5;
/** Lookback window in days for brain observations. */
export declare const BRAIN_LOOKBACK_DAYS = 7;
/**
 * Compute candidate weight from citation_count and quality_score.
 * Formula: `(citation_count / 10) * quality_score` capped at 1.0.
 */
export declare function computeBrainWeight(citationCount: number, qualityScore: number): number;
/**
 * Run the BRAIN ingester against the provided DatabaseSync handle.
 *
 * Returns at most {@link BRAIN_INGESTER_LIMIT} candidates, sorted by weight
 * descending. Returns an empty array if the database has no matching entries
 * or if any error occurs (errors are swallowed to never crash the tick).
 *
 * @param nativeDb - Open DatabaseSync handle to brain.db. May be null if
 *   brain.db has not been initialised; this is treated as zero candidates.
 * @returns Ranked ProposalCandidate array (may be empty).
 */
export declare function runBrainIngester(nativeDb: DatabaseSync | null): ProposalCandidate[];
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