/**
 * Per-item fan-out lowering.
 *
 * n8n runs every node once per incoming item, so a "read"/"list" node that
 * returns an array implicitly loops its downstream consumers. Pikku's graph is
 * declarative (one value per node, no ambient fan-out), so that edge is lowered
 * into an explicit `graph:fanout` node: the collection source stays a node, and
 * its single per-item consumer is pulled out of the graph flow and invoked once
 * per element as the fanout's `child`, with its `$json` references rebound to the
 * per-item `$item`.
 *
 * v1 is deliberately single-hop: it only lowers a collection source feeding
 * exactly one terminal consumer whose sole input is that source. Longer per-item
 * sub-chains are left untouched (and surfaced by the harness) until the child is
 * generalised to a synthesised per-item sub-graph.
 */
import type { NextValue, Topology } from './topology.js';
export interface FanoutMap {
    /** Synthetic `graph:fanout` node id inserted between the source and consumer. */
    mapNodeId: string;
    /** The collection source whose array output is fanned out over. */
    sourceNodeId: string;
    /** The absorbed consumer's nodeId — its input becomes the map's childInput. */
    childNodeId: string;
    /** The rpc the map invokes once per item. */
    childRpc: string;
    /** The map node's own successor (the consumer's original next), if any. */
    next?: NextValue;
}
export interface FanoutPlan {
    maps: FanoutMap[];
    /** Consumer nodeIds pulled out of the graph flow (invoked only as a child). */
    absorbed: Set<string>;
    /** Source nodeId → the map node its `next` must be rewritten to. */
    sourceNext: Map<string, string>;
}
export declare function planFanout(topo: Topology): FanoutPlan;