/**
 * metadata-filter.ts — Structured metadata tags + predicate filtering (#84).
 *
 * Tags are serialized as a JSON suffix appended to the stored text:
 *   "<original text>\n[tags:{"key":"val","priority":3}]"
 *
 * This is backward compatible: rows without a [tags:{...}] suffix simply have
 * no tags and will not match any tag predicate (they remain visible when no
 * filter is specified).
 *
 * Supported filter predicates (mirroring MongoDB-style operators):
 *   { "key": "value" }                   — equality ($eq)
 *   { "key": { "$eq": "value" } }        — explicit equality
 *   { "key": { "$ne": "value" } }        — not-equal
 *   { "key": { "$in": ["a","b"] } }      — membership
 *   { "key": { "$nin": ["a","b"] } }     — not-in
 *   { "key": { "$gte": 1, "$lte": 5 } }  — range (numeric or string lex)
 *   { "key": { "$gt": 0 } }              — exclusive lower bound
 *   { "key": { "$lt": 10 } }             — exclusive upper bound
 *   { "key": { "$exists": true } }       — key presence check
 *
 * Multiple top-level keys are ANDed together.
 */
export type TagValue = string | number | boolean | null;
export type Tags = Record<string, TagValue>;
type ScalarPredicate = {
    $eq?: TagValue;
    $ne?: TagValue;
    $in?: TagValue[];
    $nin?: TagValue[];
    $gt?: number | string;
    $gte?: number | string;
    $lt?: number | string;
    $lte?: number | string;
    $exists?: boolean;
};
export type FilterPredicate = Record<string, TagValue | ScalarPredicate>;
/** Append tags to text for storage. Idempotent (replaces any existing suffix). */
export declare function serializeTags(text: string, tags: Tags): string;
/** Remove a [tags:{...}] suffix if present, returning the original text. */
export declare function stripTagsSuffix(text: string): string;
/** Parse tags from stored text. Returns null if no tags suffix present. */
export declare function parseTags(text: string | null | undefined): Tags | null;
export declare function validateTags(raw: unknown): Tags;
export declare function validateFilter(raw: unknown): FilterPredicate;
/**
 * Returns true if `tags` satisfies all predicates in `filter`.
 * Top-level keys are ANDed. Missing tags match only $exists:false and $nin.
 */
export declare function matchesFilter(tags: Tags | null, filter: FilterPredicate): boolean;
export {};
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