エクスクルーシブ

Attache `<mv-attache>`

形状を考慮したグリッドパッキングエディターです。子要素はそれぞれ固定グリッドの w × h セルを占め（ダッシュボードのウィジェット、印刷シート上のステッカー、棚の箱、部屋のテーブルなど）、何が収まり何が収まらないかがグリッド上でひと目でわかります。

文化的リファレンス

バイオハザード4、Capcom（監督：三上真司）（2005年、ゲーム）。アタッシュケースのインベントリは固定グリッドで、各アイテムは形に応じてセルを占有します。アイテムを回転させて並べ替え、すべてを収めますが、何が入り何が入らないかはひと目でわかります。ここでは、大きさの異なるアイテム（ウィジェット、ステッカー、箱）を固定グリッド上に詰め込みます。セルごとに収まるか衝突するかを示すライブのフットプリント、ドラッグ中の回転、ワンクリックの自動パッキング、収まらないもののためのトレイを備えています。

仕組み

形状を考慮したグリッドパッキングエディター：各子要素が固定グリッドの w × h セルを占有し（ダッシュボードのウィジェット、印刷シート上のステッカー、棚の箱、部屋のテーブル）、何が収まり何が収まらないかをグリッドがひと目で示します。アイテムをドラッグすると、そのフットプリントがセル単位でグリッド上に表示されます：収まる場所はクリーンなセル、ほかのアイテムと重なる場所や境界からはみ出す場所はハッチングと輪郭付きのセルで示されます。それを言葉で伝えるタグ（「Fits · col 3, row 1」、「Overlaps Support queue」）も表示され、邪魔になっているアイテムには輪郭が付きます。R キー、右クリック、または2本目の指で、ドラッグ中にアイテムを回転できます（w と h が入れ替わり、つかんだ位置も一緒に回転）。ドロップが拒否されると、アイテムは元の位置へ飛んで戻ります。Auto-arrange は、決定的な first-fit-decreasing パッカー（複数の並び順、回転可、最良の結果を採用）で、ロックされたアイテムの周りにすべてを詰め込みます。収まらないものはオーバーフロートレイ（「2 items don't fit」）で待機し、各アイテムは今すぐ置けるスペースがあるかどうかを示し、ダブルクリックで配置できます。キーボードで完全に操作でき、レイアウトはデータとして公開され（layout プロパティ、mv-layout-change、キャンセル可能な mv-drop）、ロックされたアイテムは動かず、セルは要素の幅に合わせて拡大縮小します。packLayout() はサーバー側のレイアウト用に純粋関数としてエクスポートされています。

カテゴリー	レイアウト
タイプ	Web Component（`<mv-attache>`）
ステータス	安定版
同時にインストールされるもの	button
Keywords	exclusive, culture, grid, packing, bin-packing, layout-editor, dashboard, widgets, drag-and-drop, rotate, footprint, collision, tetris, inventory, print-sheet, seating-plan, slotting, keyboard, overflow

When to use

Users arrange dashboard widgets of different sizes on a fixed grid and must see what fits before they drop
A print sheet, label run or storage slot plan must use a fixed number of cells as fully as possible
Some items are pinned by an admin and the rest must be repacked around them in one click
The app must know, and be able to veto, every placement as structured data (x, y, w, h, rotated)

Avoid when

The layout is fixed by the designer and users never rearrange it → use Bento Grid instead
Items move between workflow stages in ordered lists rather than occupying 2D cells → use Kanban instead
Items are freely positioned at any pixel, rotated at any angle or overlap on purpose (a whiteboard, a free canvas)

インストール

node scripts/add.mjs attache --out ./src/marvelous

Marvelous UI の MCP サーバーを使う AI エージェント：install_components({ slugs: ["attache"], target_dir: "<absolute path>/src/marvelous", framework: "react" })。

コピーされるファイル（依存関係を含む）：tokens/tokens.css, core/base.css, components/button/button.css, core/dom.js, core/element.js, core/motion.js, components/attache/attache.js, components/attache/attache.css。

使い方

基本となるマークアップです。ここから属性、data-*、CSS 変数でカスタマイズしてください：

<div id="at-demo" style="width:min(100%,62rem);margin-inline:auto">
  <style>
    #at-demo { display:grid; gap:1.25rem }
    #at-demo .at-head { display:flex; align-items:flex-end; justify-content:space-between; gap:.75rem 1rem; flex-wrap:wrap }
    #at-demo .at-head h3 { margin:0; font-size:1.125rem; letter-spacing:-.01em }
    #at-demo .at-head p { margin:.125rem 0 0; color:var(--mv-fg-muted); font-size:.8125rem }
    #at-demo .at-controls { display:flex; align-items:center; gap:.5rem 1rem; flex-wrap:wrap }
    #at-demo .mv-choice { font-size:.8125rem }
    #at-demo #at-board { --mv-attache-ratio:.6 }

    /* Widgets: the content adapts to the footprint through data-w / data-h. */
    #at-demo .dw { display:flex; flex-direction:column; gap:.25rem; padding:.625rem .75rem; font-size:.75rem; line-height:1.3 }
    #at-demo .dw-k { display:flex; align-items:center; gap:.375rem; color:var(--mv-fg-muted); font-weight:500; white-space:nowrap; overflow:hidden; text-overflow:ellipsis }
    #at-demo .dw-k svg { flex:none; width:.875rem; height:.875rem }
    #at-demo .dw-v { font-size:1.25rem; font-weight:650; letter-spacing:-.02em; font-variant-numeric:tabular-nums; color:var(--mv-fg) }
    #at-demo .dw[data-w="1"][data-h="1"] .dw-v { font-size:1rem }
    #at-demo .dw-d { color:var(--mv-fg-muted); white-space:nowrap; overflow:hidden; text-overflow:ellipsis }
    #at-demo .dw-up { color:var(--mv-success) }
    #at-demo .dw-bars { flex:1; display:flex; align-items:flex-end; gap:4px; min-height:0; padding-top:.25rem }
    #at-demo .dw-bars i { flex:1; height:var(--v); border-radius:3px 3px 1px 1px; background:color-mix(in oklab, var(--mv-accent) 70%, transparent) }
    #at-demo .dw-bars i:last-child { background:var(--mv-accent) }
    #at-demo .dw-rows { display:grid; gap:.3125rem; margin-top:auto }
    #at-demo .dw-row { display:grid; grid-template-columns:minmax(0,1fr) auto; gap:.125rem .5rem; align-items:center }
    #at-demo .dw-row span:first-child { overflow:hidden; text-overflow:ellipsis; white-space:nowrap }
    #at-demo .dw-row span:nth-child(2) { color:var(--mv-fg-muted); font-variant-numeric:tabular-nums }
    #at-demo .dw-row b { grid-column:1 / -1; height:4px; border-radius:2px; background:var(--mv-bg-muted); overflow:hidden }
    #at-demo .dw-row b::before { content:""; display:block; width:var(--v); height:100%; background:var(--mv-accent) }
    #at-demo .dw-list { list-style:none; margin:auto 0 0; padding:0; display:grid; gap:.25rem }
    #at-demo .dw-list li { display:flex; justify-content:space-between; gap:.5rem; color:var(--mv-fg-muted) }
    #at-demo .dw-list li span:first-child { color:var(--mv-fg); overflow:hidden; text-overflow:ellipsis; white-space:nowrap }
    #at-demo .dw-list li span:last-child { font-variant-numeric:tabular-nums; white-space:nowrap }
    #at-demo .dw-spark { width:100%; height:1.5rem; margin-top:auto; color:var(--mv-accent) }
    #at-demo .dw-prog { height:6px; margin-top:auto; border-radius:3px; background:var(--mv-bg-muted); overflow:hidden }
    #at-demo .dw-prog::before { content:""; display:block; width:60%; height:100%; background:var(--mv-success) }
    #at-demo .dw[data-h="1"] .dw-extra { display:none }
    #at-demo .dw[data-w="1"] .dw-wide { display:none }
    #at-demo .dw[data-attache-orient="landscape"] .dw-list { grid-auto-flow:column; grid-auto-columns:minmax(0,1fr); gap:.75rem }
    #at-demo .dw[data-attache-orient="landscape"] .dw-list li { flex-direction:column; gap:0 }
    #at-demo .dw[data-attache-orient="portrait"] .dw-d { white-space:normal }

    #at-demo .at-lower { display:grid; grid-template-columns:minmax(0,1fr) minmax(0,1fr); gap:1.25rem; align-items:start }
    #at-demo .at-panel { display:grid; gap:.75rem; padding:1rem 1.125rem; border:1px solid var(--mv-border); border-radius:var(--mv-radius-xl); background:var(--mv-surface) }
    #at-demo .at-panel h4 { display:flex; align-items:center; justify-content:space-between; gap:.5rem; margin:0; font-size:.8125rem; font-weight:600 }
    #at-demo .at-panel p { margin:0; color:var(--mv-fg-muted); font-size:.75rem; line-height:1.45 }
    #at-demo .at-json { margin:0; max-height:13.5rem; overflow:auto; padding:.625rem .75rem; border-radius:var(--mv-radius-lg); background:var(--mv-bg-subtle); font:.6875rem/1.55 var(--mv-font-mono); color:var(--mv-fg-muted); white-space:pre }
    #at-demo .at-json b { color:var(--mv-fg); font-weight:500 }
    #at-demo .at-log { min-height:1.1rem; font:.6875rem/1.45 var(--mv-font-mono); color:var(--mv-fg-muted) }
    #at-demo .at-log[data-veto] { color:var(--mv-danger) }

    /* Second scenario: a sheet of stickers laid out for print. */
    #at-demo #at-sheet { --mv-attache-ratio:1; --mv-attache-board:var(--mv-surface) }
    #at-demo .st { display:grid; place-items:center; padding:.25rem; text-align:center; font-size:.6875rem; font-weight:600; line-height:1.2; border-width:1.5px }
    #at-demo .st small { display:block; font-weight:400; color:var(--mv-fg-muted) }
    #at-demo .st[data-shape="round"] { border-radius:50% }
    #at-demo .st-a { background:color-mix(in oklab, var(--mv-accent) 12%, var(--mv-surface-raised)) }
    #at-demo .st-b { background:color-mix(in oklab, var(--mv-success) 12%, var(--mv-surface-raised)) }
    #at-demo .st-c { background:color-mix(in oklab, var(--mv-warning) 14%, var(--mv-surface-raised)) }
    #at-demo .at-hint { margin:0; color:var(--mv-fg-muted); font-size:.75rem; text-align:center }
    @media (max-width:48rem) { #at-demo .at-lower { grid-template-columns:minmax(0,1fr) } }
    /* Tiny tiles (phones): keep the title only, then the key figure. */
    #at-demo .dw { container-type:size }
    @media (max-width:40rem) {
      @container (max-width:5.5rem) { #at-demo .dw-d, #at-demo .dw-list, #at-demo .dw-rows, #at-demo .dw-bars, #at-demo .dw-k svg, #at-demo .dw-k:has(+ .dw-v) { display:none } #at-demo .dw-v { font-size:.6875rem; letter-spacing:-.03em } }
      @container (max-height:3.25rem) { #at-demo .dw-d, #at-demo .dw-prog, #at-demo .dw-v small { display:none } #at-demo .dw-v { font-size:.875rem } }
    }
    @media (max-width:40rem) { #at-demo .dw { padding:.3125rem .4375rem; font-size:.6875rem } }
    @media (max-width:40rem) { #at-demo #at-board { --mv-attache-ratio:1.25; --mv-attache-gap:4px; --mv-attache-padding:4px } }
  </style>

  <div class="at-head">
    <div>
      <h3>Home dashboard</h3>
      <p>Tarnwick Labs · drag widgets, press R or right-click mid-drag to rotate</p>
    </div>
    <div class="at-controls">
      <label class="mv-choice" data-control="end">
        <input type="checkbox" role="switch" class="mv-switch" id="at-edit" checked>
        <span class="mv-choice-text"><span class="mv-choice-title">Edit layout</span></span>
      </label>
      <label class="mv-choice" data-control="end">
        <input type="checkbox" role="switch" class="mv-switch" id="at-rotate" checked>
        <span class="mv-choice-text"><span class="mv-choice-title">Rotation</span></span>
      </label>
      <button class="mv-button" data-variant="ghost" data-size="sm" type="button" id="at-reset">Reset</button>
    </div>
  </div>

  <mv-attache id="at-board" cols="8" rows="4" label="Dashboard layout">
    <div class="dw" data-id="revenue" data-w="4" data-h="2" data-x="0" data-y="0" data-rotatable="false">
      <span class="dw-k"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" aria-hidden="true"><path d="M4 20V10M10 20V4M16 20v-7M22 20H2"/></svg><strong>Revenue</strong></span>
      <span class="dw-v">$482,190</span>
      <span class="dw-d"><span class="dw-up">+12.4%</span> vs. August</span>
      <span class="dw-bars dw-extra" aria-hidden="true"><i style="--v:38%"></i><i style="--v:52%"></i><i style="--v:44%"></i><i style="--v:61%"></i><i style="--v:57%"></i><i style="--v:70%"></i><i style="--v:64%"></i><i style="--v:78%"></i><i style="--v:73%"></i><i style="--v:86%"></i><i style="--v:81%"></i><i style="--v:96%"></i></span>
    </div>
    <div class="dw" data-id="traffic" data-w="2" data-h="2" data-x="4" data-y="0">
      <span class="dw-k"><strong>Traffic by region</strong></span>
      <div class="dw-rows">
        <div class="dw-row"><span>North America</span><span>42%</span><b style="--v:42%"></b></div>
        <div class="dw-row"><span>Europe</span><span>31%</span><b style="--v:31%"></b></div>
        <div class="dw-row dw-extra"><span>Asia Pacific</span><span>19%</span><b style="--v:19%"></b></div>
      </div>
    </div>
    <div class="dw" data-id="goals" data-w="2" data-h="1" data-x="6" data-y="0" data-locked data-label="Q3 goals">
      <span class="dw-k"><strong>Q3 goals</strong> · pinned by admin</span>
      <span class="dw-d">3 of 5 on track</span>
      <span class="dw-prog" aria-hidden="true"></span>
    </div>
    <div class="dw" data-id="conversion" data-w="2" data-h="1" data-x="6" data-y="1">
      <span class="dw-k"><strong>Conversion</strong></span>
      <span class="dw-v">3.8% <small class="dw-up" style="font-size:.6875rem;font-weight:500">+0.4 pt</small></span>
    </div>
    <div class="dw" data-id="users" data-w="2" data-h="1" data-x="1" data-y="2">
      <span class="dw-k"><strong>Active users</strong></span>
      <span class="dw-v">18,204</span>
    </div>
    <div class="dw" data-id="support" data-w="2" data-h="2" data-x="4" data-y="2">
      <span class="dw-k"><strong>Support queue</strong></span>
      <span class="dw-v">14 open</span>
      <ul class="dw-list dw-extra">
        <li><span>Refund for #48213</span><span>2h</span></li>
        <li><span>SSO login loop</span><span>5h</span></li>
      </ul>
    </div>
    <div class="dw" data-id="uptime" data-w="1" data-h="1" data-x="6" data-y="2">
      <span class="dw-k"><strong>Uptime</strong></span>
      <span class="dw-v">99.98%</span>
    </div>
    <div class="dw" data-id="orders" data-w="2" data-h="1" data-x="1" data-y="3">
      <span class="dw-k"><strong>Orders today</strong></span>
      <span class="dw-v">1,284</span>
    </div>
    <div class="dw" data-id="nps" data-w="1" data-h="1" data-x="7" data-y="3">
      <span class="dw-k"><strong>NPS</strong></span>
      <span class="dw-v">62</span>
    </div>
    <div class="dw" data-id="deploys" data-w="1" data-h="3">
      <span class="dw-k"><strong>Deploys</strong></span>
      <ul class="dw-list">
        <li><span>api 2.14</span><span>09:12</span></li>
        <li><span>web 8.3</span><span>Sep 22</span></li>
        <li><span>jobs 1.9</span><span>Sep 21</span></li>
      </ul>
    </div>
    <div class="dw" data-id="oncall" data-w="2" data-h="1">
      <span class="dw-k"><strong>On call</strong></span>
      <span class="dw-d">Priya Raman · until 6 PM</span>
    </div>
  </mv-attache>

  <div class="at-lower">
    <section class="at-panel" aria-label="Layout data">
      <h4>layout <span class="mv-badge" data-variant="secondary" data-shape="pill" id="at-count">11 items</span></h4>
      <pre class="at-json" id="at-json"></pre>
      <div class="at-log" id="at-log" aria-live="polite">Revenue is kept in the top row by an mv-drop handler.</div>
    </section>
    <section class="at-panel" aria-label="Sticker sheet">
      <h4>Sticker sheet <span class="mv-badge" data-variant="secondary" data-shape="pill">6 × 4 · print</span></h4>
      <p>Same component, square cells: lay out a print run, rotate labels to squeeze in one more.</p>
      <mv-attache id="at-sheet" cols="6" rows="4" label="Sticker sheet">
        <div class="st st-a" data-id="logo-1" data-w="2" data-h="2" data-x="0" data-y="0" data-shape="round" data-rotatable="false">Tarnwick<small>logo, 2 in</small></div>
        <div class="st st-b" data-id="ship-1" data-w="3" data-h="2" data-x="2" data-y="0">Ship to<small>address label</small></div>
        <div class="st st-c" data-id="fragile" data-w="1" data-h="2" data-x="5" data-y="0">Fragile</div>
        <div class="st" data-id="qr-1" data-w="1" data-h="1" data-x="0" data-y="2">QR</div>
        <div class="st" data-id="qr-2" data-w="1" data-h="1" data-x="1" data-y="2">QR</div>
        <div class="st st-b" data-id="thanks" data-w="3" data-h="1" data-x="2" data-y="2">Thank you!</div>
        <div class="st st-a" data-id="logo-2" data-w="2" data-h="2" data-shape="round" data-rotatable="false">Tarnwick<small>logo, 2 in</small></div>
        <div class="st st-c" data-id="this-side" data-w="2" data-h="1">This side up</div>
      </mv-attache>
    </section>
  </div>
  <p class="at-hint">Keyboard: Tab to a widget, Space to pick up, arrows to move, R to rotate, Space to drop, Escape to cancel, Delete to set aside</p>

  <script type="module">
    const board = document.getElementById("at-board");
    await customElements.whenDefined("mv-attache");
    const $ = (id) => document.getElementById(id);
    const initial = board.layout;
    const log = $("at-log");
    const names = { revenue: "Revenue", traffic: "Traffic by region", goals: "Q3 goals", conversion: "Conversion", users: "Active users", support: "Support queue", uptime: "Uptime", orders: "Orders today", nps: "NPS", deploys: "Deploys", oncall: "On call" };

    const paint = () => {
      const pre = $("at-json");
      pre.replaceChildren();
      for (const e of board.layout) {
        const b = document.createElement("b");
        b.textContent = `"${e.id}"`.padEnd(13);
        const pos = e.x === null ? "tray        " : `x ${e.x}, y ${e.y}`.padEnd(12);
        pre.append("{ id ", b, ` ${pos} ${e.w}×${e.h}${e.rotated ? " rotated" : ""}${e.locked ? " locked" : ""} }\n`);
      }
      const n = board.overflow.length;
      $("at-count").textContent = n ? `${n} in tray` : "all placed";
      $("at-count").dataset.variant = n ? "warning" : "success";
    };
    paint();

    board.addEventListener("mv-drop", (e) => {
      const { id, to } = e.detail;
      // App rule: the revenue chart stays in the top row.
      if (id === "revenue" && (to.tray || to.y !== 0)) {
        e.preventDefault();
        log.textContent = "mv-drop vetoed: Revenue stays in the top row.";
        log.dataset.veto = "";
        return;
      }
      delete log.dataset.veto;
      log.textContent = to.tray ? `mv-drop · ${names[id]} → tray` : `mv-drop · ${names[id]} → x ${to.x}, y ${to.y}${to.rotated ? " (rotated)" : ""}`;
    });
    board.addEventListener("mv-layout-change", (e) => {
      paint();
      if (e.detail.reason === "arrange") {
        delete log.dataset.veto;
        log.textContent = `mv-layout-change · arrange · ${e.detail.overflow.length ? `${e.detail.overflow.length} don't fit` : "everything fits"}`;
      }
    });
    $("at-edit").addEventListener("change", (e) => { board.disabled = !e.target.checked; });
    $("at-rotate").addEventListener("change", (e) => { board.noRotate = !e.target.checked; });
    $("at-reset").addEventListener("click", () => {
      board.layout = initial;
      paint();
      delete log.dataset.veto;
      log.textContent = "Layout reset.";
    });
  </script>
</div>

API

Attributes

Name	タイプ	Default	Description
`cols`	number (1-64)	`8`	Number of columns. Changing it (or rows) keeps every item that still fits, moves the others to the first free spot and sends the rest to the tray (mv-layout-change with reason "resize").
`rows`	number (1-64)	`4`	Number of rows. The grid never grows: capacity is the point.
`label`	string	`Layout`	Accessible name of the grid (“Dashboard layout, 8 columns by 4 rows”).
`no-rotate`	boolean		Disables rotation everywhere (dragging, keyboard, auto-arrange, room check in the tray).
`disabled`	boolean		View mode: the layout is shown as is, nothing can be picked up, items leave the tab order and the empty cells fade out.
`bar`	"true" \| "false"	`true`	"false" hides the status bar (usage meter and the built-in Auto-arrange button); call autoArrange() from your own control.
`data-w / data-h`	number (cells)	`1`	On an item: its current footprint. Kept up to date by the component (swapped on rotation), so [data-w="1"] or [data-attache-orient="portrait"] can adapt its content. Changing them from the app re-validates the item.
`data-x / data-y`	number (0-based)		On an item: initial position. Items without one, or whose spot is taken, go to the first free spot without rotation, else to the tray. Reflected while the item is on the grid, removed while it is in the tray.
`data-id`	string		On an item: id used in layout and events (else the element id, else item-N).
`data-label`	string		On an item: name used in announcements (else the first heading, strong or [data-attache-title], else its text).
`data-locked`	boolean		On an item: cannot be dragged, set aside or moved by Auto-arrange (the others are packed around it). Shows a padlock.
`data-rotatable`	"false"		On an item: never rotated (a chart that must stay landscape, a round sticker).
`data-rotated`	boolean		On an item: set by the component when its footprint is swapped relative to its natural orientation.
`data-attache-handle`	marker		On an element inside an item: only this handle starts a drag. Without one, the whole item drags except links, buttons, fields and [data-attache-nodrag].
`data-attache-orient / data-attache-state / data-attache-room`	set by the component		Items get landscape \| portrait \| square, picked (pointer drag origin) \| grabbed (keyboard), and yes \| no in the tray. The host gets data-dragging while something is being placed and data-overflow while an item has no room.

Properties

Name	タイプ	Description
`layout`	Array<{ id, x, y, w, h, rotated, locked }>	Current layout in reading order, tray items last with x and y null. Set it to restore a saved layout: listed items go where you say if it is free, unlisted ones keep their spot or take the first free one, the rest go to the tray. Setting it does not emit mv-layout-change. Can be set before the element is defined.
`overflow`	string[]	Ids of the items waiting in the tray (read-only).
`strings`	Partial<Record<string, string>>	Overrides for every visible text and announcement (grid, help, item, itemTray, arrange, usage, trayAll, trayAllOne, traySome, trayDrop, fits, overlaps, out, picked, moved, rotated, dropped, returned, vetoed, cancelled, setAside, arranged…). English defaults, {placeholders} filled in.
`cols / rows / label / noRotate / disabled / bar`	reflected	Mirror the attributes.

Methods

Name	Description
`autoArrange({ rotate? })`	Packs every unlocked item (rotation follows no-rotate unless given). Items glide to their new spot. Returns { placed, overflow }. Emits mv-layout-change with reason "arrange".
`fits(item, x, y, { rotated? })`	Would this item (element or id) fit there? Returns { fits, out, blockers: [id] }.
`moveItem(item, x, y, { rotated? })`	Moves an item from code (no mv-drop). Returns false if it does not fit or is locked.
`setAside(item)`	Sends an item to the tray (no mv-drop). Returns false if it is locked or already there.
`refresh()`	Re-reads the items. Rarely needed: added and removed children and changes of data-w, data-h, data-locked, data-label or data-rotatable are picked up automatically.
`packLayout(items, { cols, rows, rotate }) (named export)`	The packer as a pure function, without DOM: items [{ id, w, h, x?, y?, locked?, rotatable?, rotated? }] → { layout, overflow }. Deterministic, so it can run on the server or in a worker.

Events

Name	Description
`mv-drop`	Cancelable, before a user placement is committed (pointer, keyboard or double click in the tray). detail: { id, item, from, to, source: "pointer" \| "keyboard", layout (the layout if accepted) }; from and to are { tray, x, y, w, h, rotated }. preventDefault() refuses it: the item goes back and “Move refused” is announced.
`mv-layout-change`	After every committed change. detail: { layout, overflow, reason: "drop" \| "tray" \| "arrange" \| "api" \| "resize" \| "dom" }. Save the layout here.

Content structure

Name	Description
`(content)`	The items, as direct children with data-w / data-h. They are moved into the grid (.mv-attache-board) or the tray, and sorted in reading order; render them once and drive later changes through layout or DOM additions and removals. The floating copy used while dragging is a clone appended to the element, so style items with a class, not through .mv-attache-board.

CSS classes

Name	Description
`mv-attache-item`	Added to every item: a zero-specificity tile (border, radius, raised surface) you can restyle freely. .mv-attache-proxy is the floating clone while dragging.
`mv-attache-board / -cells / -cell`	The grid and its decorative empty cells (aria-hidden).
`mv-attache-ghost`	Footprint preview (aria-hidden): .mv-attache-ghost-cell[data-cell="fit \| blocked \| out"] and .mv-attache-ghost-tag (icon, verdict, position). data-state="fit \| blocked \| out".
`mv-attache-bar`	Status bar: .mv-attache-meter / -meter-fill, .mv-attache-usage and the .mv-attache-arrange button (.mv-button).
`mv-attache-tray`	Overflow tray: .mv-attache-tray-head (-icon, -text), .mv-attache-tray-items, .mv-attache-tray-empty. data-state="empty \| aside \| overflow", data-over while a drag hovers it.

CSS variables

Name	Default	Description
`--mv-attache-ratio`	`1`	Row height as a fraction of the column width (0.6 for dashboard tiles, 1 for square cells).
`--mv-attache-gap`	`var(--mv-space-2)`	Gap between cells.
`--mv-attache-padding`	`var(--mv-space-2)`	Inner padding of the grid and the tray.
`--mv-attache-fit`	`var(--mv-success)`	Color of cells where the item fits.
`--mv-attache-blocked`	`var(--mv-danger)`	Color of hatched cells (overlap, out of bounds) and of items in the way.
`--mv-attache-board`	`var(--mv-bg-subtle)`	Grid background.
`--mv-attache-meter`	`var(--mv-accent)`	Usage meter fill.

Accessibility

The grid is a labelled group (“Dashboard layout, 8 columns by 4 rows”), not role="grid" or "application": items span several cells, so cell-by-cell grid navigation would misrepresent them, and application mode would take browse mode away from the widgets' own content. Instead every item is a focusable group with aria-roledescription “movable tile” whose name states its size and position (“Revenue chart, 2 by 2, at column 3 row 1”, “…, set aside, room available”, “…, locked”), described by the instructions; items are kept in DOM reading order (rows, then columns) after every change so Tab follows the visual order, and focus is preserved when they move (moveBefore where supported). Keyboard: Space or Enter picks up (a set-aside item starts at the first spot where it fits), arrow keys move the footprint one cell (Shift: by the item's own size), R rotates, Space or Enter drops, Escape or Tab cancels, Delete or Backspace sets the item aside; each step is announced assertively (“Column 4, row 2. Overlaps Map.”), and a blocked drop is refused with its reason while the item stays picked up. Pointer drops, refusals, vetoes and Auto-arrange results (“Arranged 11 items. Everything fits.”) are announced politely. The footprint verdict never relies on color: blocked and out-of-bounds cells are hatched and outlined dashed, the tag names the verdict and the blocking items, and items in the way are outlined; the tray's “Fits / No room” chips are words too. Links, buttons and fields inside an item keep working and never start a drag. Touch: drag with one finger, tap with a second to rotate. Reduced motion (OS or data-motion="reduce"): no glide, landing, fly-back, settle ring or rotation wiggle; positions change instantly. Forced colors: fit cells are outlined in Highlight, blocked ones dashed in CanvasText, icons use CanvasText.