diff --git a/web/arm-ik-solver.js b/web/arm-ik-solver.js
index 0384bf7..38a346c 100644
--- a/web/arm-ik-solver.js
+++ b/web/arm-ik-solver.js
@@ -226,10 +226,10 @@ function make(cfg) {
     return out;
   }
 
-  const inLimit = q => {
+  const inLimit = q => {                 // 取否定式：NaN 候选必须落选（原写法 NaN 比较全 false 会放行）
     for (let i = 0; i < 5; i++) {
       const t = LIM[ORDER[i]];
-      if (q[i] < t.lo - 1e-9 || q[i] > t.hi + 1e-9) return false;
+      if (!(q[i] >= t.lo - 1e-9 && q[i] <= t.hi + 1e-9)) return false;
     }
     return true;
   };
@@ -309,7 +309,7 @@ function make(cfg) {
         const p = fk(q, tool);
         const dx = p[0] - target[0], dy = p[1] - target[1], dz = p[2] - target[2];
         const e2 = dx * dx + dy * dy + dz * dz;
-        if (e2 > tol2) continue;
+        if (!(e2 <= tol2)) continue;          // 否定式：e2 为 NaN（目标含 NaN/Inf）时继续走拒绝分支
         const c = scoreBranch(q, Math.sqrt(e2));
         if (c && (!best || c.rcost < best.rcost - 1e-12)) best = c;
       }
diff --git a/web/ik-glue.js b/web/ik-glue.js
index a2835f0..396da3e 100644
--- a/web/ik-glue.js
+++ b/web/ik-glue.js
@@ -210,6 +210,7 @@ function refreshTarget() {
 let anim = null;
 function setJoints(q, doAnim) {
   if (doAnim) { animTo(q, 620); return; }
+  anim = null;                                 // 直接写入必须取消在飞动画，否则入场动画会覆写实时解
   for (let i = 0; i < 6; i++) {
     const id = ORDER[i]; ang[id] = q[i];
     const s = $('s' + id), v = $('v' + id);
@@ -445,7 +446,7 @@ function rollAngleAt(e) {
   const pl = new THREE.Plane().setFromNormalAndCoplanarPoint(n, gTgt.position);
   const hit = new THREE.Vector3();
   ray2.setFromCamera(ndc2(e), cam);                    // 该版本 setFromCamera 不返回 this，勿链式
-  if (!ray2.ray.intersectPlane(pl, hit)) return 0;
+  if (!ray2.ray.intersectPlane(pl, hit)) return null;   // 错过平面：该帧不参与滚转（返回 0 会按 -a0 突跳）
   const v = hit.sub(gTgt.position);
   const up = Math.abs(n.y) > 0.9 ? new THREE.Vector3(1, 0, 0) : new THREE.Vector3(0, 1, 0);
   const u = new THREE.Vector3().crossVectors(n, up).normalize();
@@ -497,6 +498,7 @@ cv.addEventListener('pointermove', e => {
   if (grab.pose === 'roll') {                        // 拖圆环：绕轴滚转
     dragged = true;
     const a1 = rollAngleAt(e);
+    if (a1 == null) return;                           // 射线错过平面：跳过该帧，角度不变
     POSE.roll = S.wrap180(POSE.roll + S.wrap180(a1 - grab.a0));
     grab.a0 = a1;
     syncPoseInputs(); refreshTarget();
diff --git a/web/index.html b/web/index.html
index f798325..9ff8d79 100644
--- a/web/index.html
+++ b/web/index.html
@@ -1442,10 +1442,10 @@ function make(cfg) {
     return out;
   }
 
-  const inLimit = q => {
+  const inLimit = q => {                 // 取否定式：NaN 候选必须落选（原写法 NaN 比较全 false 会放行）
     for (let i = 0; i < 5; i++) {
       const t = LIM[ORDER[i]];
-      if (q[i] < t.lo - 1e-9 || q[i] > t.hi + 1e-9) return false;
+      if (!(q[i] >= t.lo - 1e-9 && q[i] <= t.hi + 1e-9)) return false;
     }
     return true;
   };
@@ -1525,7 +1525,7 @@ function make(cfg) {
         const p = fk(q, tool);
         const dx = p[0] - target[0], dy = p[1] - target[1], dz = p[2] - target[2];
         const e2 = dx * dx + dy * dy + dz * dz;
-        if (e2 > tol2) continue;
+        if (!(e2 <= tol2)) continue;          // 否定式：e2 为 NaN（目标含 NaN/Inf）时继续走拒绝分支
         const c = scoreBranch(q, Math.sqrt(e2));
         if (c && (!best || c.rcost < best.rcost - 1e-12)) best = c;
       }
@@ -2237,6 +2237,7 @@ function refreshTarget() {
 let anim = null;
 function setJoints(q, doAnim) {
   if (doAnim) { animTo(q, 620); return; }
+  anim = null;                                 // 直接写入必须取消在飞动画，否则入场动画会覆写实时解
   for (let i = 0; i < 6; i++) {
     const id = ORDER[i]; ang[id] = q[i];
     const s = $('s' + id), v = $('v' + id);
@@ -2472,7 +2473,7 @@ function rollAngleAt(e) {
   const pl = new THREE.Plane().setFromNormalAndCoplanarPoint(n, gTgt.position);
   const hit = new THREE.Vector3();
   ray2.setFromCamera(ndc2(e), cam);                    // 该版本 setFromCamera 不返回 this，勿链式
-  if (!ray2.ray.intersectPlane(pl, hit)) return 0;
+  if (!ray2.ray.intersectPlane(pl, hit)) return null;   // 错过平面：该帧不参与滚转（返回 0 会按 -a0 突跳）
   const v = hit.sub(gTgt.position);
   const up = Math.abs(n.y) > 0.9 ? new THREE.Vector3(1, 0, 0) : new THREE.Vector3(0, 1, 0);
   const u = new THREE.Vector3().crossVectors(n, up).normalize();
@@ -2524,6 +2525,7 @@ cv.addEventListener('pointermove', e => {
   if (grab.pose === 'roll') {                        // 拖圆环：绕轴滚转
     dragged = true;
     const a1 = rollAngleAt(e);
+    if (a1 == null) return;                           // 射线错过平面：跳过该帧，角度不变
     POSE.roll = S.wrap180(POSE.roll + S.wrap180(a1 - grab.a0));
     grab.a0 = a1;
     syncPoseInputs(); refreshTarget();
diff --git a/web/机器人手臂3D查看器.html b/web/机器人手臂3D查看器.html
index f798325..9ff8d79 100644
--- a/web/机器人手臂3D查看器.html
+++ b/web/机器人手臂3D查看器.html
@@ -1442,10 +1442,10 @@ function make(cfg) {
     return out;
   }
 
-  const inLimit = q => {
+  const inLimit = q => {                 // 取否定式：NaN 候选必须落选（原写法 NaN 比较全 false 会放行）
     for (let i = 0; i < 5; i++) {
       const t = LIM[ORDER[i]];
-      if (q[i] < t.lo - 1e-9 || q[i] > t.hi + 1e-9) return false;
+      if (!(q[i] >= t.lo - 1e-9 && q[i] <= t.hi + 1e-9)) return false;
     }
     return true;
   };
@@ -1525,7 +1525,7 @@ function make(cfg) {
         const p = fk(q, tool);
         const dx = p[0] - target[0], dy = p[1] - target[1], dz = p[2] - target[2];
         const e2 = dx * dx + dy * dy + dz * dz;
-        if (e2 > tol2) continue;
+        if (!(e2 <= tol2)) continue;          // 否定式：e2 为 NaN（目标含 NaN/Inf）时继续走拒绝分支
         const c = scoreBranch(q, Math.sqrt(e2));
         if (c && (!best || c.rcost < best.rcost - 1e-12)) best = c;
       }
@@ -2237,6 +2237,7 @@ function refreshTarget() {
 let anim = null;
 function setJoints(q, doAnim) {
   if (doAnim) { animTo(q, 620); return; }
+  anim = null;                                 // 直接写入必须取消在飞动画，否则入场动画会覆写实时解
   for (let i = 0; i < 6; i++) {
     const id = ORDER[i]; ang[id] = q[i];
     const s = $('s' + id), v = $('v' + id);
@@ -2472,7 +2473,7 @@ function rollAngleAt(e) {
   const pl = new THREE.Plane().setFromNormalAndCoplanarPoint(n, gTgt.position);
   const hit = new THREE.Vector3();
   ray2.setFromCamera(ndc2(e), cam);                    // 该版本 setFromCamera 不返回 this，勿链式
-  if (!ray2.ray.intersectPlane(pl, hit)) return 0;
+  if (!ray2.ray.intersectPlane(pl, hit)) return null;   // 错过平面：该帧不参与滚转（返回 0 会按 -a0 突跳）
   const v = hit.sub(gTgt.position);
   const up = Math.abs(n.y) > 0.9 ? new THREE.Vector3(1, 0, 0) : new THREE.Vector3(0, 1, 0);
   const u = new THREE.Vector3().crossVectors(n, up).normalize();
@@ -2524,6 +2525,7 @@ cv.addEventListener('pointermove', e => {
   if (grab.pose === 'roll') {                        // 拖圆环：绕轴滚转
     dragged = true;
     const a1 = rollAngleAt(e);
+    if (a1 == null) return;                           // 射线错过平面：跳过该帧，角度不变
     POSE.roll = S.wrap180(POSE.roll + S.wrap180(a1 - grab.a0));
     grab.a0 = a1;
     syncPoseInputs(); refreshTarget();
diff --git a/机器人手臂3D查看器.html b/机器人手臂3D查看器.html
index f798325..9ff8d79 100644
--- a/机器人手臂3D查看器.html
+++ b/机器人手臂3D查看器.html
@@ -1442,10 +1442,10 @@ function make(cfg) {
     return out;
   }
 
-  const inLimit = q => {
+  const inLimit = q => {                 // 取否定式：NaN 候选必须落选（原写法 NaN 比较全 false 会放行）
     for (let i = 0; i < 5; i++) {
       const t = LIM[ORDER[i]];
-      if (q[i] < t.lo - 1e-9 || q[i] > t.hi + 1e-9) return false;
+      if (!(q[i] >= t.lo - 1e-9 && q[i] <= t.hi + 1e-9)) return false;
     }
     return true;
   };
@@ -1525,7 +1525,7 @@ function make(cfg) {
         const p = fk(q, tool);
         const dx = p[0] - target[0], dy = p[1] - target[1], dz = p[2] - target[2];
         const e2 = dx * dx + dy * dy + dz * dz;
-        if (e2 > tol2) continue;
+        if (!(e2 <= tol2)) continue;          // 否定式：e2 为 NaN（目标含 NaN/Inf）时继续走拒绝分支
         const c = scoreBranch(q, Math.sqrt(e2));
         if (c && (!best || c.rcost < best.rcost - 1e-12)) best = c;
       }
@@ -2237,6 +2237,7 @@ function refreshTarget() {
 let anim = null;
 function setJoints(q, doAnim) {
   if (doAnim) { animTo(q, 620); return; }
+  anim = null;                                 // 直接写入必须取消在飞动画，否则入场动画会覆写实时解
   for (let i = 0; i < 6; i++) {
     const id = ORDER[i]; ang[id] = q[i];
     const s = $('s' + id), v = $('v' + id);
@@ -2472,7 +2473,7 @@ function rollAngleAt(e) {
   const pl = new THREE.Plane().setFromNormalAndCoplanarPoint(n, gTgt.position);
   const hit = new THREE.Vector3();
   ray2.setFromCamera(ndc2(e), cam);                    // 该版本 setFromCamera 不返回 this，勿链式
-  if (!ray2.ray.intersectPlane(pl, hit)) return 0;
+  if (!ray2.ray.intersectPlane(pl, hit)) return null;   // 错过平面：该帧不参与滚转（返回 0 会按 -a0 突跳）
   const v = hit.sub(gTgt.position);
   const up = Math.abs(n.y) > 0.9 ? new THREE.Vector3(1, 0, 0) : new THREE.Vector3(0, 1, 0);
   const u = new THREE.Vector3().crossVectors(n, up).normalize();
@@ -2524,6 +2525,7 @@ cv.addEventListener('pointermove', e => {
   if (grab.pose === 'roll') {                        // 拖圆环：绕轴滚转
     dragged = true;
     const a1 = rollAngleAt(e);
+    if (a1 == null) return;                           // 射线错过平面：跳过该帧，角度不变
     POSE.roll = S.wrap180(POSE.roll + S.wrap180(a1 - grab.a0));
     grab.a0 = a1;
     syncPoseInputs(); refreshTarget();