/**
 * Pure decision logic for how a drag should be routed when the cursor is over a
 * Column wrapper. A Column hosts two distinct drop systems that must never
 * overlap:
 *   1. Its cells accept drops INTO the column.
 *   2. The wrapper itself accepts drops BEFORE/AFTER the whole column.
 *
 * To avoid the ambiguity that previously let a drop land before a column while
 * a cell looked targeted, the column body always routes to the cells. A
 * before/after-column drop is only offered where there is a genuine reason to
 * drop next to the column:
 *   - the column is the FIRST/LAST top-level block (drop at the very start/end
 *     of the document), or
 *   - the adjacent top-level block is ALSO a column (so a block can be inserted
 *     in the gap between two stacked columns).
 *
 * This is extracted as a pure function so the branching can be unit-tested
 * without a live editor / DOM.
 */
export interface ColumnCellBand {
    /** Top edge (clientY) of the topmost cell. */
    top: number;
    /** Bottom edge (clientY) of the bottommost cell. */
    bottom: number;
}
export interface ResolveColumnDropZoneArgs {
    /** Whether the column is a direct child of the document (top level). */
    isRootColumn: boolean;
    /** Index of the column among its siblings. */
    columnIndex: number;
    /** Number of siblings in the column's parent. */
    siblingCount: number;
    /** Whether the previous sibling is also a column. */
    prevIsColumn: boolean;
    /** Whether the next sibling is also a column. */
    nextIsColumn: boolean;
    /** Current cursor Y (clientY). */
    mouseY: number;
    /** Measured vertical band covered by the column's cells, if known. */
    cellBand: ColumnCellBand | null;
}
export type ColumnDropZone = 
/** Drop before the whole column (top edge). */
"before"
/** Drop after the whole column (bottom edge). */
 | "after"
/** Let the cell drop targets own the drop (no column indicator). */
 | "into-cells"
/** Cell band not measured yet — caller should fall back to generic logic. */
 | "fallthrough";
/** Returns whether the top/bottom before-after strips should be offered. */
export declare const columnStripsAllowed: ({ isRootColumn, columnIndex, siblingCount, prevIsColumn, nextIsColumn, }: Pick<ResolveColumnDropZoneArgs, "isRootColumn" | "columnIndex" | "siblingCount" | "prevIsColumn" | "nextIsColumn">) => {
    allowTopStrip: boolean;
    allowBottomStrip: boolean;
};
export declare const resolveColumnDropZone: (args: ResolveColumnDropZoneArgs) => ColumnDropZone;