/**
 * Pure layout math for the paper view's draggable three-pane split: the
 * outline rail width in px (0 = collapsed strip), the editor's share of the
 * remaining width (the preview takes the rest), the drag-to-width clamping,
 * and the localStorage persistence codec. DOM-free so every rule is
 * unit-testable — PaperView feeds pointer deltas in and renders the result.
 * @module dsh-client-ui-mimir/client/paper-layout
 */
/** The paper view's pane widths: rail in px, editor as a 0–1 share of the rest. */
export interface PaperLayout {
    /** Outline rail width in px; 0 renders the collapsed slim strip. */
    readonly rail: number;
    /** Editor share (0–1) of the width left after the rail; the preview gets the rest. */
    readonly editor: number;
    /** The header toggle's collapsed flag; a drag to 0 collapses via `rail` instead. */
    readonly collapsed: boolean;
}
/** localStorage key the layout persists under. */
export declare const PAPER_LAYOUT_STORAGE_KEY = "mimir.paperLayout";
/** Shipped layout: 180px rail, editor/preview at roughly 7:5. */
export declare const PAPER_LAYOUT_DEFAULT: PaperLayout;
/** The rail never grows past this (px). Section titles are short; the rail
 *  is a navigation aid, not a reading surface. */
export declare const RAIL_MAX_WIDTH = 240;
/** The rail never takes more than this share of the container width. */
export declare const RAIL_MAX_SHARE = 0.2;
/** A rail dragged below this width snaps to 0 (collapsed) instead of a sliver. */
export declare const RAIL_COLLAPSE_BELOW = 60;
/** The collapsed rail renders as a slim strip of this width (px). */
export declare const RAIL_COLLAPSED_STRIP = 44;
/** The editor never shrinks below this (px). */
export declare const EDITOR_MIN_WIDTH = 360;
/** The preview never shrinks below this (px). */
export declare const PREVIEW_MIN_WIDTH = 280;
/** Horizontal chrome (padding + border) each pane adds around its
 *  content-box minimum — the floors in footprint terms. */
export declare const PANE_FRAME_PX = 30;
/**
 * The rail width after one drag: the start width plus the horizontal pointer
 * delta, clamped to [0, {@link RAIL_MAX_WIDTH}], snapping to 0 (the collapsed
 * strip) below {@link RAIL_COLLAPSE_BELOW} so a near-collapse never leaves an
 * unreadable sliver.
 */
export declare function railWidthFromDrag(startRail: number, deltaX: number): number;
/**
 * The rail width that actually renders for a container of `containerPx`.
 * The rail is the first pane to give ground: it is capped by
 * {@link RAIL_MAX_WIDTH} and {@link RAIL_MAX_SHARE} of the container, and
 * when the container cannot hold the rail plus both pane floors (the
 * {@link EDITOR_MIN_WIDTH}/{@link PREVIEW_MIN_WIDTH} content minimums plus
 * their {@link PANE_FRAME_PX} chrome) the rail shrinks to whatever is left —
 * snapping to 0 (the collapsed strip) below {@link RAIL_COLLAPSE_BELOW}.
 * Anything still short after that is the container's horizontal scrollbar's
 * job; the editor and preview floors are never yielded. A collapsed (0) or
 * non-positive-container input passes through untouched. `containerPx`
 * excludes the inter-pane gaps (the caller subtracts them).
 */
export declare function railWidthForContainer(rail: number, containerPx: number): number;
/**
 * The editor share after one split-handle drag. `editorPx` is the dragged-to
 * editor width and `availablePx` the combined editor+preview width at drag
 * start; the share clamps so the editor keeps at least {@link EDITOR_MIN_WIDTH}
 * and the preview at least {@link PREVIEW_MIN_WIDTH} (the editor minimum wins
 * when the container is too narrow for both).
 */
export declare function editorShareFromDrag(editorPx: number, availablePx: number): number;
/**
 * Read the persisted layout, falling back to {@link PAPER_LAYOUT_DEFAULT} on
 * a missing key, malformed JSON, or out-of-range values. Storage access is
 * injected as a `getItem` so the codec stays DOM-free.
 */
export declare function loadPaperLayout(getItem: (key: string) => string | null): PaperLayout;
/** Serialize one layout for localStorage. */
export declare function serializePaperLayout(layout: PaperLayout): string;
/** Below this content width (px) the paper view degrades to a one-pane tab layout. */
export declare const PAPER_NARROW_BREAKPOINT = 900;
/** The pane the narrow-width tab bar can select. */
export type PaperSoloPane = 'editor' | 'preview';
/**
 * Which pane takes the whole content area: under the narrow breakpoint the
 * tab bar decides (the rail and split handle hide via the fullscreen CSS);
 * at full width the explicit fullscreen flag decides (null = split).
 */
export declare function paperSoloPane(narrow: boolean, tab: PaperSoloPane, fullscreen: PaperSoloPane | null): PaperSoloPane | null;
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