import type Database from "better-sqlite3";
/**
 * Slow-query threshold, in milliseconds.
 *
 * Measured, not guessed. Against the live 22 MB `cache.db` on this machine
 * (583 conversations, 38 717 index rows, warm page cache), 3 600 read samples
 * across the twelve statements the hot paths actually run gave p50 0.03 ms,
 * p99 0.87 ms, p99.9 1.43 ms, max 1.83 ms; 1 200 write samples gave p99
 * 0.09 ms with rare WAL-checkpoint spikes to 4.37 ms. So *every* healthy query
 * on this machine finishes inside ~4.4 ms, and the checkpoint spikes are the
 * only thing anywhere near that.
 *
 * 35 ms sits two anchors above that: it is 8x the slowest healthy operation
 * ever observed, so checkpoint spikes can never page anyone, and it is more
 * than the 34 ms *end-to-end* time of the fastest complete conversation fetch
 * measured on this box. A query crossing it therefore cost more on its own
 * than an entire healthy request — which is the point at which a warn line is
 * worth the bytes it occupies in the log.
 *
 * Override with `THREADBASE_DB_SLOW_QUERY_MS`; <= 0 disables slow logging.
 */
export declare const DEFAULT_SLOW_QUERY_MS = 35;
/**
 * Time every `.get()` / `.all()` / `.run()` on every statement this connection
 * prepares.
 *
 * Wrapping `prepare` is what makes this one edit per database instead of one
 * per query: `better-sqlite3` is synchronous, so a call's wall time *is* its
 * cost, and every statement in the process — the 45 in ConversationCache, the
 * 4 in RuntimeStore, and the ~40 more inside the repositories that share these
 * handles — is created here. Measured overhead is +0.09 µs on an 8.9 µs call
 * (~1%), which is why it is always on rather than behind a flag.
 *
 * Only the three terminal methods are replaced, as own properties; `iterate`,
 * `pluck`, `raw`, `columns` and `bind` keep resolving to the prototype
 * untouched. A statement that throws is not recorded — the error surfaces on
 * its own path.
 */
export declare function instrumentDatabase(db: Database.Database, options?: {
    slowMs?: number;
}): Database.Database;
/**
 * Name the statements in a `{ name: Statement }` bag after their keys, so a
 * slow-query line reads `getMessageIndexWindow` rather than
 * `select:conversation_message_index`.
 *
 * Separate from `instrumentDatabase` because `prepare` cannot know the key its
 * result is about to be assigned to. Statements from a connection that was
 * never instrumented are skipped.
 */
export declare function labelStatements(statements: object): void;
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