/**
 * Session entity table: reversible placeholders for coherent chat.
 *
 * Blanket `[REDACTED]` makes the assistant's replies nonsense. Instead each
 * redacted value gets a stable, typed placeholder (`[GIVEN_NAME_1]`, `[SSN_2]`)
 * that survives across turns: the same raw value always maps to the same token,
 * so the model can reason about "GIVEN_NAME_1" and we {@link rehydrate} the real
 * value back into its reply before display.
 *
 * The map lives only on the client. What leaves the device is placeholdered
 * text; the table never crosses the wire.
 */
import { type PiiLabel, type Span } from "./types";
/** Result of scrubbing one message. */
export interface ScrubResult {
    /** Text with PII replaced by placeholders. Safe to send/log. */
    readonly text: string;
    /** Placeholders introduced or reused in this message. */
    readonly placeholders: readonly string[];
}
/**
 * Optional display aliases for placeholder tokens. By default a GIVEN_NAME span
 * becomes `[GIVEN_NAME_1]`; pass `{ GIVEN_NAME: "NAME" }` to get `[NAME_1]` instead.
 * Only the visible token changes — detection and policy are unaffected.
 */
export type PlaceholderAliases = Partial<Record<PiiLabel, string>>;
/** Token shape minted by the table; also the regex used to find them on the
 * way back. Kept in one place so scrub and rehydrate can never disagree. */
export declare const PLACEHOLDER_PATTERN: RegExp;
/**
 * A per-conversation store mapping raw PII values to stable placeholders.
 * Keyed by `label + normalized value` so "John" stays `GIVEN_NAME_1` on every turn
 * and casing/whitespace noise doesn't mint duplicate tokens.
 */
export declare class SessionEntityTable {
    private readonly aliases;
    private readonly keepLabels;
    private readonly forward;
    private readonly reverse;
    private readonly counters;
    constructor(aliases?: PlaceholderAliases, keepLabels?: ReadonlySet<PiiLabel>);
    /** The visible name used in tokens for a label (alias or the label itself). */
    private displayName;
    /** Get or mint the placeholder for a given label+value. Idempotent. */
    placeholderFor(label: PiiLabel, value: string): string;
    /**
     * Replace each redactable span with its placeholder. Spans are pre-sorted
     * right-to-left by {@link applyPolicy}, so splicing never invalidates an
     * earlier offset.
     */
    scrub(raw: string, spans: readonly Span[]): ScrubResult;
    /**
     * Restore real values in an assistant reply. Used on the *outbound* response
     * so the user sees "John", not "[NAME_1]". Unknown tokens are left intact.
     */
    rehydrate(text: string): string;
    /** True if `token` is a placeholder this table can resolve. */
    knows(token: string): boolean;
}
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