/**
 * Per-parent Proposal Deduplication Gate (T1592).
 *
 * Prevents the T1555-style burst failure mode where the sentient proposer
 * runs twice on the same audit output and creates near-identical pairs of
 * proposed tasks (e.g. T1544/T1550, T1545/T1551, ...).
 *
 * Strategy
 * --------
 * Before {@link transactionalInsertProposal} is called, the propose tick
 * computes a stable `dedupHash` from
 *
 *   sha256(`${normalizedParentId}
${normalizedTitle}
${normalizedRationale}`)
 *
 * where `normalize = lowercase + strip punctuation + collapse whitespace`.
 *
 * The hash is then checked against existing tier-2 proposals in tasks.db
 * within a 24-hour window:
 *   - parent scope: same `parent_id` (or "<root>" if both null) AND same hash
 *   - timestamp window: `created_at >= datetime('now', '-1 day')`
 *   - tier-2 only: `labels_json LIKE '%sentient-tier2%'`
 *
 * If a match is found the proposal is REJECTED, the rejection is appended
 * to `.cleo/audit/sentient-dedup.jsonl`, and the candidate is dropped.
 *
 * If no match is found the hash is embedded into `tasks.notes_json` (as part
 * of the existing `proposal-meta` envelope, see {@link ProposedTaskMeta}) and
 * future ticks will see it via the same query path. This avoids a schema
 * migration — the existing proposal-meta JSON is the single source of truth.
 *
 * @task T1592 (Foundation Lockdown · Wave A · Worker 4)
 * @see ADR-054 — Sentient Loop Tier-2
 */
import type { DatabaseSync } from 'node:sqlite';
/** Path (relative to projectRoot) of the dedup-rejection audit log. */
export declare const SENTIENT_DEDUP_AUDIT_FILE = ".cleo/audit/sentient-dedup.jsonl";
/**
 * Default look-back window for dedup checks, in hours.
 * Mirrors the wording of T1592: "within last 24h".
 */
export declare const DEFAULT_DEDUP_WINDOW_HOURS = 24;
/** Inputs for {@link computeDedupHash}. */
export interface DedupHashInput {
    /** Parent task ID. `null` / `undefined` are coerced to a sentinel. */
    parentId: string | null | undefined;
    /** Proposal title (will be normalized). */
    title: string;
    /**
     * Proposal acceptance criteria, rationale, or description.
     * The mission spec calls this `normalizedAcceptance`; for the Tier-2
     * proposer this is the `rationale` field of {@link ProposalCandidate}.
     */
    acceptance: string;
}
/** Outcome of {@link checkDedupCollision}. */
export interface DedupCheckResult {
    /** `true` when a dup is detected and the proposal MUST be skipped. */
    isDuplicate: boolean;
    /** When `isDuplicate=true`, the existing task ID that owns the matching hash. */
    existingTaskId?: string;
    /** Stable dedup hash regardless of outcome (callers persist it on insert). */
    dedupHash: string;
}
/** Persisted shape inside `.cleo/audit/sentient-dedup.jsonl`. */
export interface DedupRejectionRecord {
    /** ISO-8601 timestamp of the rejection. */
    timestamp: string;
    /** Reason discriminant. */
    reason: 'per-parent-dedup';
    /** The dedup hash that collided. */
    dedupHash: string;
    /** Parent task ID (null preserved in JSON for clarity). */
    parentId: string | null;
    /** The would-have-been-inserted candidate title. */
    title: string;
    /** Proposal source (brain | nexus | test). */
    source: string;
    /** External source ID (brain entry id, nexus node id, etc.). */
    sourceId: string;
    /** ID of the existing task whose hash matched. */
    existingTaskId: string;
    /** Look-back window applied, in hours. */
    windowHours: number;
}
/**
 * Normalize a free-text field for hash-stable comparison.
 *
 * Steps (in order):
 *   1. Lower-case
 *   2. Strip every code point NOT in `[a-z0-9\s]`
 *      (Unicode-aware — accented Latin letters are stripped, matching the
 *      "strip punctuation" intent for English-language proposal titles.)
 *   3. Collapse runs of whitespace to a single space
 *   4. Trim leading/trailing whitespace
 *
 * @param raw - Input text. `null` / `undefined` become the empty string.
 * @returns Normalized form, suitable for use as a hash input segment.
 */
export declare function normalizeForDedup(raw: string | null | undefined): string;
/**
 * Compute the per-parent dedup hash.
 *
 * The hash is sha-256 over `parent | title | acceptance` (all normalized,
 * separated by `
`). Stable across processes and machines — same input
 * always yields the same hex digest.
 *
 * @param input - Parent + title + acceptance.
 * @returns 64-char lowercase hex sha-256 digest.
 */
export declare function computeDedupHash(input: DedupHashInput): string;
/** Options for {@link checkDedupCollision}. */
export interface DedupCheckOptions {
    /** Open DatabaseSync handle to tasks.db. May be null (then no-op). */
    tasksDb: DatabaseSync | null;
    /** The candidate hash inputs. */
    candidate: DedupHashInput;
    /**
     * Look-back window in hours. Defaults to {@link DEFAULT_DEDUP_WINDOW_HOURS}.
     * Set to `0` to disable the time bound (useful for tests).
     */
    windowHours?: number;
}
/**
 * Query tasks.db for an existing tier-2 proposal whose
 * `notes_json` contains the same `dedupHash` AND that lives under the same
 * parent (or root scope) AND was created within the look-back window.
 *
 * The check is deliberately conservative:
 *   - parent scope: rows are filtered by `parent_id IS :parentId` (with the
 *     `<root>` sentinel mapped to `IS NULL`)
 *   - time bound: `created_at >= datetime('now', '-N hours')`
 *   - tier-2 only: `labels_json LIKE '%sentient-tier2%'`
 *   - hash match: `notes_json LIKE '%"dedupHash":"<hex>"%'` (substring match
 *     is safe — the hex digest is 64 chars of `[0-9a-f]` and cannot collide
 *     with any other JSON value).
 *
 * @param opts - Check options.
 * @returns DedupCheckResult; `isDuplicate=true` when a collision is found.
 */
export declare function checkDedupCollision(opts: DedupCheckOptions): DedupCheckResult;
/** Inputs for {@link recordDedupRejection}. */
export interface DedupRejectionInput {
    /** Project root (audit log is written under `<root>/.cleo/audit/`). */
    projectRoot: string;
    /** Parent task ID (null preserved). */
    parentId: string | null;
    /** Proposal title. */
    title: string;
    /** Source (brain | nexus | test). */
    source: string;
    /** External source ID. */
    sourceId: string;
    /** Hash that collided. */
    dedupHash: string;
    /** Existing task ID that owns the matching hash. */
    existingTaskId: string;
    /** Window applied (defaults to {@link DEFAULT_DEDUP_WINDOW_HOURS}). */
    windowHours?: number;
}
/**
 * Append a single NDJSON line to `.cleo/audit/sentient-dedup.jsonl`
 * documenting a rejected proposal.
 *
 * The directory is created if missing. The write is best-effort — failures
 * are surfaced via the returned promise (callers should `await` and log on
 * failure but MUST NOT propagate the error into the propose tick result).
 *
 * @param input - Rejection details.
 */
export declare function recordDedupRejection(input: DedupRejectionInput): Promise<void>;
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