diff --git a/static/app.js b/static/app.js
index f485c5c..bcd2aa6 100644
--- a/static/app.js
+++ b/static/app.js
@@ -324,16 +324,25 @@ function dagSize() {
 }
 
 function dagFitView() {
-  // 画布适配视口：缩放并居中，让全部节点可见
+  // 画布适配视口：基于节点实际包围盒缩放并居中，让全部节点可见
   const s = dagState;
   const box = $('#dag-box');
-  const {width, height} = dagSize();
   if (!box || !s) return;
+  const poss = Object.values(s.pos || {});
+  if (!poss.length) return;
+  const minX = Math.min(...poss.map(p => p.x)) - 120;
+  const maxX = Math.max(...poss.map(p => p.x)) + 120;
+  const minY = Math.min(...poss.map(p => p.y)) - 120;
+  const maxY = Math.max(...poss.map(p => p.y)) + 120;
+  const cw = Math.max(200, maxX - minX), ch = Math.max(200, maxY - minY);
   const bw = box.clientWidth, bh = box.clientHeight;
-  const scale = Math.max(0.25, Math.min(1, (bw - 60) / width, (bh - 60) / height));
+  const scale = Math.max(0.25, Math.min(1, (bw - 60) / cw, (bh - 60) / ch));
   s.scale = scale;
-  s.tx = (bw - width * scale) / 2;
-  s.ty = (bh - height * scale) / 2;
+  // 节点包围盒中心（viewBox 坐标）对准视口中心
+  const cx = DAG_M + (minX + maxX) / 2;
+  const cy = DAG_M + (minY + maxY) / 2;
+  s.tx = bw / 2 - cx * scale;
+  s.ty = bh / 2 - cy * scale;
   dagApplyView();
   saveDagState();
 }
@@ -382,6 +391,7 @@ function drawDag() {
   const body = $('#tab-body');
   if (!body) return;
   const NW = 140, NHW = 70;   // 节点宽 / 半宽
+  const M = DAG_M;             // svg 盒边距：节点平移/缩放后仍在盒内可命中
   const dagText = t => {
     const raw = `#${t.id} ${t.title}`;
     return raw.length > 13 ? raw.slice(0, 13) + '…' : raw;
@@ -397,9 +407,9 @@ function drawDag() {
         <button onclick="dagZoomTo(1)" title="一键回到 100% 原始视图">100%</button>
       </div>
       <div class="dag-trash" id="dag-trash" onclick="openDagTrash()" title="点击查看回收站">🗑️ 删除区<span class="cnt" id="dag-trash-cnt">0</span></div>
-      <svg id="dag-svg" width="${width}" height="${Math.max(480, height)}" viewBox="0 0 ${width} ${height}" style="transform-origin:0 0">
+      <svg id="dag-svg" width="${width + M * 2}" height="${Math.max(480, height) + M * 2}" viewBox="${-M} ${-M} ${width + M * 2} ${height + M * 2}" style="transform-origin:0 0">
         <defs><marker id="arrow" markerWidth="8" markerHeight="8" refX="7" refY="3" orient="auto"><path d="M0,0 L8,3 L0,6 Z" fill="#4a5878"/></marker></defs>
-        <rect id="dag-bg" x="-4000" y="-4000" width="${width + 8000}" height="${height + 8000}" fill="var(--panel)"/>
+        <rect id="dag-bg" x="${-M - 1000}" y="${-M - 1000}" width="${width + 2 * M + 2000}" height="${height + 2 * M + 2000}" fill="var(--panel)"/>
         ${edges.map(e => {
           const a = dagState.pos[e.from], b = dagState.pos[e.to];
           if (!a || !b) return '';
@@ -426,6 +436,7 @@ function drawDag() {
 
 let dagBound = false;   // window 级监听只绑定一次
 let dagDrag = null;        // 模块级拖拽状态（box 重绑后 window handler 仍可访问）
+const DAG_M = 3000;        // svg 盒边距：节点平移/缩放后仍在盒内可命中
 function bindDagEvents() {
   const box = $('#dag-box');
   if (!box) return;
@@ -509,7 +520,7 @@ function bindDagEvents() {
       if (!svgEl2) return;
       svgEl2.querySelectorAll('.dag-node').forEach(g => {
         const nid = Number(g.dataset.id);
-        const pp = s.pos[nid];
+        const pp = st.pos[nid];
         if (!pp) return;
         g.querySelector('rect').setAttribute('x', pp.x - 70);
         g.querySelector('rect').setAttribute('y', pp.y - 24);
@@ -527,7 +538,7 @@ function bindDagEvents() {
         projCtx.tasks.forEach(t => {
           if (t.id !== tid) return;
           (t.depends_on || []).forEach(d => {
-            const b = s.pos[d];
+            const b = st.pos[d];
             if (!b) return;
             const path = svgEl2.querySelector(`path[data-e="${d}-${tid}"]`);
             if (!path) return;
@@ -662,20 +673,20 @@ function renderDag() {
   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）
+  // 节点是否全部在视口内？任一越界则自动适配（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;
+  let allVisible = !bb;
   if (bb) {
-    tasks.forEach(t => {
+    allVisible = tasks.every(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 (!p) return true;
+      const vx = bb.left + dagState.tx + (DAG_M + p.x) * dagState.scale;
+      const vy = bb.top + dagState.ty + (DAG_M + p.y) * dagState.scale;
+      return vx < bb.right && vx > bb.left && vy < bb.bottom && vy > bb.top;
     });
   }
-  if (!anyVisible || !savedView) dagFitView();
+  if (!allVisible || !savedView) dagFitView();
 }
 
 async function runWorkflow() {