/**
 * postgres-mcp — Audit Logger
 *
 * Async-buffered JSONL writer for the audit trail. Appends one
 * JSON object per line to a configurable file path, or writes to
 * stderr for containerised deployments (`--audit-log stderr`).
 *
 * Non-throwing by design: audit failures log to stderr but never
 * propagate to tool callers.
 */
import type { AuditConfig, AuditEntry } from "./types.js";
export declare class AuditLogger {
    readonly config: AuditConfig;
    private buffer;
    private flushTimer;
    private activeFlush;
    private closed;
    private dirEnsured;
    private readonly stderrMode;
    constructor(config: AuditConfig);
    /**
     * Append an audit entry to the buffer.
     * Non-blocking — the entry is serialised and queued; the
     * actual file write happens on the next flush cycle.
     */
    log(entry: AuditEntry): void;
    /**
     * Flush the buffer to disk.
     * Safe to call concurrently — serialises via `this.activeFlush` Promise.
     */
    flush(): Promise<void>;
    /**
     * Gracefully close the logger — flush remaining entries and stop the timer.
     */
    close(): Promise<void>;
    /**
     * Read the most recent audit entries from the log file.
     * Uses a streaming tail-read: only the last TAIL_READ_BYTES (64 KB) are
     * read from disk, preventing O(n) memory spikes for large audit logs.
     * Used by the `postgres://audit` resource.
     *
     * @param count Maximum number of entries to return (default 50)
     */
    recent(count?: number): Promise<AuditEntry[]>;
    /**
     * Ensure the parent directory of the log file exists.
     */
    private ensureDirectory;
    /**
     * Rotate the log file if it exceeds the configured size limit.
     * Keeps up to 5 rotated files (`.1` through `.5`); older data is discarded.
     * Rotation failure is non-fatal — audit must not block tool execution.
     */
    private rotateIfNeeded;
}
//# sourceMappingURL=logger.d.ts.map