/**
 * fold-legacy-register.ts, move the workspace register from the pre-split
 * location into the shared tier, once, without losing a row.
 *
 * ── The merge, and its tie-break ──────────────────────────────────────────
 *
 * Both halves of the document are keyed lists, so the merge is an id-keyed
 * union: `workspaces` keyed on `root` (already normalized, coverage flows down
 * that subtree, so the normalized path IS the identity), `declines` likewise.
 *
 * THE TIE-BREAK IS THE LATER `registeredAt`, and where they tie the destination
 * copy wins. Two reasons it is that and not something cleverer:
 *
 *  - `registeredAt` is the only ordering the record carries. Preferring the
 *    legacy copy wholesale would resurrect a stale label or origin; preferring
 *    the shared copy wholesale would drop a registration made after an updated
 *    product had already written the shared file.
 *  - Field-wise merging is specifically WRONG for `checkpointEligible`. Its
 *    own contract is "absent means false … one surface's self-recording must
 *    never silently widen another consumer's checkpoint scope" (see
 *    registration/types.ts), so OR-ing eligibility across two copies would
 *    widen the automatic-checkpoint boundary behind the operator's back. Whole
 *    records win or lose together.
 *
 * Idempotent: a second fold over the same pair produces the same document, so
 * re-running it on every boot is free.
 */
export interface FoldLegacyRegisterResult {
    /** Rows in the destination that were not there before this fold. */
    readonly added: number;
    /** Rows the legacy copy replaced because its `registeredAt` was later. */
    readonly updated: number;
    /** Total rows in the destination afterwards. */
    readonly total: number;
}
/**
 * Fold `legacyPath` into `sharedPath`. Both may be absent; an absent legacy
 * file is a no-op, and an absent destination is created from the legacy rows.
 * The legacy file is NOT removed here, retiring it is the sweep's job, and it
 * only does so after this has succeeded.
 */
export declare function foldLegacyWorkspaceRegister(input: {
    readonly legacyPath: string;
    readonly sharedPath: string;
}): Promise<FoldLegacyRegisterResult>;
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