/**
 * The Retriever `search` grammar, checked before a query is sent.
 *
 * `search` is not free text. The engine parses it when the query starts
 * (pipeline-extensions `QueryFilterEvaluator.parse`, called from
 * `IndexQueryReader.createReaders`) and accepts only:
 *
 *   clause  := field '==' "value"  |  includes '(' field ',' "value" ')'
 *   field   := ident ( '.' ident )?            ident := [letters digits _]+
 *   expr    := clause, '&&' binds tighter than '||', parentheses group
 *
 * Strings have no escapes. Anything else throws inside the query Lambda before
 * the coordinator runs, so no `_DONE.json` is ever written and the caller used
 * to wait out its whole timer. Measured 2026-11-13 on the hosted demo: the
 * search `react hooks` took 202.5 s (180 s marker wait + 20 s quiet window) and
 * came back "0 events, NO_MARKER, poll again"; an outside agent retried that
 * shape for six minutes. The engine's own parser, run on the same string,
 * throws "Expected operator '==' but found 'ID:hooks' at token position 1".
 *
 * This module is a faithful port of that parser (validation only, no
 * evaluation) plus one convenience: plain words, which no valid expression can
 * contain, are rewritten to `includes(text, "...")` clauses and the caller is
 * told the original text and what ran instead.
 */
export declare const INVALID_SEARCH_PREFIX = "Invalid search expression:";
/**
 * Parse `input` with the engine's grammar. Returns the constants (field,
 * value) in order, or throws an Error whose message names the first problem.
 */
export declare function parseRetrieverSearch(input: string): Array<{
    field: string;
    value: string;
}>;
export interface NormalizedSearch {
    /** The expression to send to the engine. */
    search: string;
    /** Set when `search` differs from what the caller sent. */
    rewrittenFrom?: string;
}
/**
 * Validate a caller's `search` against the engine grammar.
 *  - a valid expression passes through unchanged;
 *  - plain words (no grammar operators) become includes(text, "...") clauses,
 *    with `rewrittenFrom` carrying the original so the agent can tell its user
 *    what was searched;
 *  - anything else throws `Invalid search expression: ...` before dispatch.
 */
export declare function normalizeRetrieverSearch(raw: string): NormalizedSearch;