DAG画布：节点拖不动根因修复 + 缩放比例显示/一键100%

- 根因：dagLayout 画布宽(1100-1360px)超出视口可用宽度(约1060px)，加上保存的偏移视图可能把节点推到视口外 → 节点不可见/不可点，表现为'拖不动'
- 修复：打开画布时若无保存视图、或节点全部在视口外，自动适配缩放(≤100%)并居中，全部节点始终可见可拖
- 新增右上角缩放控件：实时显示缩放百分比(滚轮/适配/拖动联动) + ⤢适配按钮 + 100%一键回原始视图
- 实测：真实鼠标拖动在 0.82x 缩放下精确跟随；滚轮 112%→100% 显示联动

static/app.js

@@ -323,6 +323,32 @@ function dagSize() {
   return dagLayout(tasks, idMap);
 }
 
+function dagFitView() {
+  // 画布适配视口：缩放并居中，让全部节点可见
+  const s = dagState;
+  const box = $('#dag-box');
+  const {width, height} = dagSize();
+  if (!box || !s) return;
+  const bw = box.clientWidth, bh = box.clientHeight;
+  const scale = Math.max(0.25, Math.min(1, (bw - 60) / width, (bh - 60) / height));
+  s.scale = scale;
+  s.tx = (bw - width * scale) / 2;
+  s.ty = (bh - height * scale) / 2;
+  dagApplyView();
+  saveDagState();
+}
+
+function dagZoomTo(scale) {
+  // 一键回到指定比例（100% = 原始视图）
+  const s = dagState;
+  if (!s) return;
+  s.scale = scale;
+  s.tx = 0;
+  s.ty = 0;
+  dagApplyView();
+  saveDagState();
+}
+
 function saveDagState() {
   if (!dagState) return;
   try {
@@ -340,6 +366,8 @@ function dagApplyView() {
   if (!svg) return;
   svg.style.transform = `translate(${s.tx}px, ${s.ty}px) scale(${s.scale})`;
   svg.style.transformOrigin = '0 0';
+  const pct = $('#dag-zoom-pct');
+  if (pct) pct.textContent = Math.round(s.scale * 100) + '%';
 }
 
 function drawDag() {
@@ -364,6 +392,10 @@ function drawDag() {
       <button class="btn success" ${ready.length ? '' : 'disabled'} onclick="runWorkflow()">▶ 执行整个工作流（${ready.length}）</button>
     </div>
     <div class="dag-box" id="dag-box">
+      <div class="dag-zoom" id="dag-zoom">🔍 <b id="dag-zoom-pct">100%</b>
+        <button onclick="dagFitView()" title="缩放至适配整个画布">⤢ 适配</button>
+        <button onclick="dagZoomTo(1)" title="一键回到 100% 原始视图">100%</button>
+      </div>
       <div class="dag-trash" id="dag-trash" onclick="openDagTrash()" title="点击查看回收站">🗑️ 删除区<span class="cnt" id="dag-trash-cnt">0</span></div>
       <svg id="dag-svg" width="${width}" height="${Math.max(480, height)}" viewBox="0 0 ${width} ${height}" style="transform-origin:0 0">
         <defs><marker id="arrow" markerWidth="8" markerHeight="8" refX="7" refY="3" orient="auto"><path d="M0,0 L8,3 L0,6 Z" fill="#4a5878"/></marker></defs>
@@ -627,9 +659,23 @@ function renderDag() {
     ty: savedView?.ty || 0,
     drag: null, moved: false,
   };
-  const box = $('#tab-body');
-  box.innerHTML = '';
+  const body2 = $('#tab-body');
+  body2.innerHTML = '';
   drawDag();
+  // 节点是否在视口内？不在则自动适配（防止节点被平移到视口外无法操作）
+  const box = $('#dag-box');
+  const bb = box ? box.getBoundingClientRect() : null;
+  let anyVisible = false;
+  if (bb) {
+    tasks.forEach(t => {
+      const p = dagState.pos[t.id];
+      if (!p) return;
+      const vx = bb.left + dagState.tx + p.x * dagState.scale;
+      const vy = bb.top + dagState.ty + p.y * dagState.scale;
+      if (vx < bb.right && vx > bb.left && vy < bb.bottom && vy > bb.top) anyVisible = true;
+    });
+  }
+  if (!anyVisible || !savedView) dagFitView();
 }
 
 async function runWorkflow() {

static/style.css

@@ -143,6 +143,10 @@ tr:hover td{background:var(--panel2)}
 .dag-trash{position:absolute;left:14px;bottom:14px;background:rgba(255,107,107,.1);border:1.5px dashed var(--danger);color:var(--danger);border-radius:10px;padding:8px 14px;font-size:12px;cursor:pointer;z-index:5;display:flex;align-items:center;gap:6px;backdrop-filter:blur(2px)}
 .dag-trash:hover,.dag-trash.hover{background:rgba(255,107,107,.25);border-style:solid}
 .dag-trash .cnt{background:var(--danger);color:#fff;border-radius:8px;padding:0 6px;font-size:11px}
+.dag-zoom{position:absolute;right:14px;top:14px;background:rgba(23,30,46,.88);border:1px solid var(--border);border-radius:8px;padding:4px 10px;font-size:12px;color:var(--muted);display:flex;align-items:center;gap:6px;z-index:6}
+.dag-zoom b{color:var(--text);font-weight:600;min-width:42px;text-align:center}
+.dag-zoom button{background:var(--panel2);border:1px solid var(--border);color:var(--text);border-radius:5px;padding:2px 8px;font-size:11px;cursor:pointer}
+.dag-zoom button:hover{border-color:var(--accent);color:var(--accent)}
 .alert-row{border-left:3px solid var(--border);padding:12px 14px;margin-bottom:8px;background:var(--panel2);border-radius:0 10px 10px 0;cursor:pointer}
 .alert-row.unread{border-left-color:var(--warn)}
 .alert-row.critical{border-left-color:var(--danger)}