diff --git a/src/editor/panels/TimelinePanel.test.tsx b/src/editor/panels/TimelinePanel.test.tsx
index d294637..a7e55f5 100644
--- a/src/editor/panels/TimelinePanel.test.tsx
+++ b/src/editor/panels/TimelinePanel.test.tsx
@@ -1,5 +1,6 @@
 import { afterEach, beforeEach, it, expect, vi } from "vitest";
 import { act, render, screen, fireEvent, within } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
 import { useDirectorStore, createDefaultDirectorProject } from "../store/directorStore";
 import { usePlaybackStore } from "../runtime/playbackStore";
 import {
@@ -14,6 +15,7 @@ import {
 } from "./TimelinePanel";
 import { DEFAULT_TIMELINE_FPS } from "../schema/timeline";
 import { TrajectoryPointPanel } from "./TrajectoryPointPanel";
+import { CameraPanel } from "./CameraPanel";
 
 function getDefaultCharacter() {
   return useDirectorStore.getState().project.objects.find((item) => item.kind === "character")!;
@@ -780,6 +782,28 @@ it("drags a single trajectory keyframe to change only its own time", () => {
   expect(screen.getByRole("button", { name: "轨迹关键帧 3.0s" })).toBeInTheDocument();
 });
 
+it("snaps a dragged trajectory keyframe to the nearest whole frame", () => {
+  const character = getDefaultCharacter();
+  useDirectorStore.getState().addTrajectoryPoint(character.id, [1, 0, 0]);
+  useDirectorStore.getState().addTrajectoryPoint(character.id, [2, 0, 0]);
+  useDirectorStore.getState().setTrajectoryPointTimes(character.id, [1.5, 3]);
+
+  render(<TimelinePanel />);
+  stubTrackRowLayout({}, 500);
+
+  // 第一个轨迹点落在 1.5s（= 第 45 帧，30fps）。只把它拖约 0.02s（2px）到 1.52s 这个非整帧位置，
+  // 应被吸附到最近的整帧（第 46 帧 ≈ 1.5333s）。
+  const firstKeyframe = screen.getByRole("button", { name: "轨迹关键帧 1.5s" });
+  fireEvent.pointerDown(firstKeyframe, { button: 0, pointerId: 1, clientX: 150 });
+  fireEvent.pointerMove(firstKeyframe, { pointerId: 1, clientX: 152 });
+  fireEvent.pointerUp(firstKeyframe, { pointerId: 1, clientX: 152 });
+
+  const points = getTrajectoryPoints(character.id);
+  expect(points[0].time).toBeCloseTo(46 / 30, 5);
+  // 离播放头 / 其它片段边缘都很远，所以这次吸附来自整帧网格而非其它基准
+  expect(points[1].time).toBeCloseTo(3, 5);
+});
+
 it("nudges the trajectory hold duration with the keyboard", () => {
   const character = getDefaultCharacter();
   useDirectorStore.getState().addTrajectoryPoint(character.id, [1, 0, 0]);
@@ -1234,6 +1258,80 @@ it("jumps to the first and last frame from the transport controls", () => {
   expect(usePlaybackStore.getState().playhead).toBe(5);
 });
 
+it("edits a selected camera keyframe's look rotation and commits it back to the keyframe", async () => {
+  const cameraObject = useDirectorStore.getState().project.objects.find((o) => o.kind === "camera")!;
+  useDirectorStore.getState().selectObject(cameraObject.id);
+  const cameraId = cameraObject.linkedCameraId!;
+  useDirectorStore.getState().addCameraKeyframe(cameraId, 1, {
+    position: [0, 1.5, 5],
+    lookRotation: [0, 0, 0],
+    fov: 50,
+  });
+  useDirectorStore.getState().addCameraKeyframe(cameraId, 4, {
+    position: [0, 1.5, 5],
+    lookRotation: [0, 90, 0],
+    fov: 50,
+  });
+
+  const user = userEvent.setup();
+  render(<TimelinePanel />);
+  render(<CameraPanel />);
+
+  const firstKeyframe = screen.getByRole("button", { name: "运镜关键帧 1.0s" });
+  await user.click(firstKeyframe);
+
+  const yaw = screen.getByLabelText("机位水平角");
+  await user.clear(yaw);
+  await user.type(yaw, "45");
+
+  await user.click(screen.getByRole("button", { name: "更新选中关键帧" }));
+
+  const track = useDirectorStore
+    .getState()
+    .project.timeline.cameraTracks.find((t) => t.cameraId === cameraId)!;
+  const kf = track.keyframes.find((k) => Math.abs(k.time - 1) < 1e-6)!;
+  // 期望：在关键帧上改的水平角被写回该关键帧
+  expect(kf.value.lookRotation[1]).toBeCloseTo(45, 5);
+});
+
+it("commits a camera keyframe edit even without a selected camera object (camera view mode)", async () => {
+  const cameraObject = useDirectorStore.getState().project.objects.find((o) => o.kind === "camera")!;
+  const cameraId = cameraObject.linkedCameraId!;
+  useDirectorStore.getState().selectObject(null);
+  useDirectorStore.setState({ viewMode: "camera" });
+  useDirectorStore.getState().setActiveCamera(cameraId);
+  useDirectorStore.getState().addCameraKeyframe(cameraId, 1, {
+    position: [0, 1.5, 5],
+    lookRotation: [0, 0, 0],
+    fov: 50,
+  });
+  useDirectorStore.getState().addCameraKeyframe(cameraId, 4, {
+    position: [0, 1.5, 5],
+    lookRotation: [0, 90, 0],
+    fov: 50,
+  });
+
+  const user = userEvent.setup();
+  render(<TimelinePanel />);
+  render(<CameraPanel />);
+
+  const firstKeyframe = screen.getByRole("button", { name: "运镜关键帧 1.0s" });
+  await user.click(firstKeyframe);
+
+  const yaw = screen.getByLabelText("机位水平角");
+  await user.clear(yaw);
+  await user.type(yaw, "45");
+
+  await user.click(screen.getByRole("button", { name: "更新选中关键帧" }));
+
+  const track = useDirectorStore
+    .getState()
+    .project.timeline.cameraTracks.find((t) => t.cameraId === cameraId)!;
+  const kf = track.keyframes.find((k) => Math.abs(k.time - 1) < 1e-6)!;
+  // 没选中机位物体时 selectedShot 为空，原本提交会读错机位而写不回；修复后应写回该关键帧
+  expect(kf.value.lookRotation[1]).toBeCloseTo(45, 5);
+});
+
 it("shows the frame readout with the frame rate from the settings", () => {
   useDirectorStore.getState().setTimelinePlaybackSettings({ fps: 60 });
   usePlaybackStore.getState().setPlayhead(1.5);
diff --git a/src/editor/panels/TimelinePanel.tsx b/src/editor/panels/TimelinePanel.tsx
index 07d5989..aa3f653 100644
--- a/src/editor/panels/TimelinePanel.tsx
+++ b/src/editor/panels/TimelinePanel.tsx
@@ -46,7 +46,7 @@ import {
   type CameraKeyframeValue,
   type KeyframeTransformValue,
 } from "../schema/timeline";
-import type { MotionKind } from "../schema/directorProject";
+import type { MotionClip, MotionKind } from "../schema/directorProject";
 import {
   TRAJECTORY_POINT_MIN_GAP,
   getMotionEndTime,
@@ -207,6 +207,8 @@ type TimelineTrackKind = "object" | "camera" | "character";
 
 /** 轨道拖拽的启动阈值（px）：小于它当作普通点击，避免抢走关键帧的选中点击 */
 const TRACK_DRAG_THRESHOLD_PX = 4;
+/** 时间滑块（片段 / 关键帧）吸附阈值（px）：拖动的边缘进入其它片段边缘 / 播放头这么近就吸上去 */
+const SNAP_THRESHOLD_PX = 8;
 
 /** 轨道行的纵向几何（拖拽开始时量一次就缓存，移动中只查表） */
 interface TrackRowRect {
@@ -318,6 +320,7 @@ export function TimelinePanel() {
   const updateCameraKeyframeValue = useDirectorStore((state) => state.updateCameraKeyframeValue);
   const setCameraKeyframeTimes = useDirectorStore((state) => state.setCameraKeyframeTimes);
   const applyCameraKeyframeToShot = useDirectorStore((state) => state.applyCameraKeyframeToShot);
+  const setActiveCamera = useDirectorStore((state) => state.setActiveCamera);
   const setTimelineDuration = useDirectorStore((state) => state.setTimelineDuration);
   const clearAllKeyframes = useDirectorStore((state) => state.clearAllKeyframes);
   const selectedTrajectoryPoint = useDirectorStore((state) => state.selectedTrajectoryPoint);
@@ -375,6 +378,8 @@ export function TimelinePanel() {
   const [draggingTrackKey, setDraggingTrackKey] = useState<string | null>(null);
   const dropTargetRef = useRef<{ key: string; position: TimelineTrackDropPosition } | null>(null);
   const dropIndicatorRef = useRef<HTMLDivElement | null>(null);
+  /** 吸附参考线：拖动片段 / 关键帧时，边缘吸到其它片段边缘或播放头处显示一条高亮竖线 */
+  const snapIndicatorRef = useRef<HTMLDivElement | null>(null);
   /** 当前这一次指针手势（按下 → 超过阈值才算真的开始拖拽，否则当普通点击放行） */
   const dragGestureRef = useRef<{
     pointerId: number;
@@ -402,6 +407,8 @@ export function TimelinePanel() {
     endEdge: number;
     startClientX: number;
     secondsPerPixel: number;
+    /** 拖拽开始时该角色的全部动作片段（用于「拖动换位」：依据原始布局做确定性重排） */
+    startClips?: MotionClip[];
   } | null>(null);
   /** 拖拽开始时一次性量好的行几何：移动中只查表，绝不在事件里读布局（强制同步布局 = layout thrashing） */
   const trackRectsRef = useRef(new Map<string, TrackRowRect>());
@@ -553,6 +560,9 @@ export function TimelinePanel() {
     setPlaying(false);
     setPlayhead(time);
     applyCameraKeyframeToShot(cameraId, value);
+    // 把该机位设为当前编辑机位：机位面板（CameraPanel）始终按 activeCameraId 编辑，
+    // 否则在「机位视角」或当前激活机位与选中物体不一致时，编辑的是别的机位，改动写不回这个关键帧。
+    setActiveCamera(cameraId);
     setSelectedKeyframe({ kind: "camera", targetId: cameraId, keyframeId });
   }
 
@@ -560,8 +570,17 @@ export function TimelinePanel() {
     if (!selectedKeyframe) return;
     if (selectedKeyframe.kind === "object" && selectedObject) {
       updateKeyframeValue(selectedKeyframe.targetId, selectedKeyframe.keyframeId, snapshotObjectTransform());
-    } else if (selectedKeyframe.kind === "camera" && selectedShot) {
-      updateCameraKeyframeValue(selectedKeyframe.targetId, selectedKeyframe.keyframeId, snapshotShot());
+    } else if (selectedKeyframe.kind === "camera") {
+      // 直接读「这个关键帧所属机位」的当前机位值写回，而不是 selectedShot
+      // （selectedShot 是「选中物体关联的机位」，在机位视角 / 激活机位与选中物体不一致时会对错机位，导致改了角度却写不回关键帧）。
+      const camera = project.cameras.find((c) => c.id === selectedKeyframe.targetId);
+      if (camera) {
+        updateCameraKeyframeValue(selectedKeyframe.targetId, selectedKeyframe.keyframeId, {
+          position: [...camera.transform.position] as [number, number, number],
+          lookRotation: [...camera.lookRotation] as [number, number, number],
+          fov: camera.fov,
+        });
+      }
     }
   }
   function handleDeleteSelected() {
@@ -831,17 +850,28 @@ export function TimelinePanel() {
   }
 
   /**
-   * 点轨道空白处 = 取消片段选中。
-   * 片段 / 关键帧自己的手势里会 stopPropagation，正常情况冒泡不到这里；
+   * 点轨道空白处 = 取消所有已选中的片段 / 关键帧 / 轨迹点 / 动作片段。
+   * 片段 / 关键帧 / 各类手柄自己的手势里会 stopPropagation，正常情况冒泡不到这里；
    * 但手势可能因为尺寸未就绪等原因提前返回（那时还没走到 stopPropagation），
-   * 所以这里再按事件来源兜一层，避免把刚选中的片段立刻清掉。
+   * 所以这里再按事件来源兜一层，避免把刚选中的条目立刻清掉。
    */
   function handleTimelineGridPointerDown(event: ReactPointerEvent<HTMLDivElement>) {
-    if (event.target instanceof Element && event.target.closest(".timeline-trajectory-bar, .timeline-keyframe")) {
+    // 点在交互元素（片段条 / 关键帧 / 拖拽把手 / 删除按钮 / 添加按钮 / 折叠开关）上不算空白处，
+    // 那些手势自己会处理选中，这里不能清掉它们。
+    if (
+      event.target instanceof Element &&
+      event.target.closest(
+        ".timeline-trajectory-bar, .timeline-keyframe, .timeline-trajectory-trim, .timeline-clip-delete, .timeline-add-clip-button, .timeline-track-icon-button"
+      )
+    ) {
       return;
     }
 
+    // 点轨道空白处：取消所有已选中项，让右侧编辑面板回到未选中态。
     setSelectedClip(null);
+    setSelectedKeyframe(null);
+    selectTrajectoryPoint(null, null);
+    selectMotionClip(null);
   }
 
   /**
@@ -915,7 +945,8 @@ export function TimelinePanel() {
     owner: TimelineTimeDragOwner,
     times: number[],
     startEdge: number,
-    deltaSeconds: number
+    deltaSeconds: number,
+    originalClips?: MotionClip[]
   ) {
     const endEdge = times.length > 0 ? times[times.length - 1] : startEdge;
     const minShift = -startEdge;
@@ -940,7 +971,8 @@ export function TimelinePanel() {
         owner.clipId,
         startEdge + shift,
         times[times.length - 1] + shift,
-        times[0]
+        times[0],
+        originalClips
       );
       return;
     }
@@ -1026,6 +1058,11 @@ export function TimelinePanel() {
       endEdge,
       startClientX: event.clientX,
       secondsPerPixel: duration / laneWidth,
+      // 拖动作片段本体时记录按下时刻的全部片段，供「拖动换位」使用
+      startClips:
+        owner.kind === "motionClip"
+          ? (project.objects.find((o) => o.id === owner.objectId)?.characterRig?.motionClips ?? []).map((c) => ({ ...c }))
+          : undefined,
     };
 
     // 拖动时冻结全站毛玻璃：条 / 关键帧每次重绘都会让背后 WebGL 画布重算一次模糊
@@ -1045,24 +1082,27 @@ export function TimelinePanel() {
     event.preventDefault();
     event.stopPropagation();
 
-    const deltaTime = (event.clientX - drag.startClientX) * drag.secondsPerPixel;
+    const rawDelta = (event.clientX - drag.startClientX) * drag.secondsPerPixel;
+    // 吸附：把要移动的边缘吸到其它片段边缘 / 播放头（磁性对齐）
+    const { delta, snappedTime } = computeSnappedDelta(drag, rawDelta);
+    showSnapIndicator(snappedTime);
 
     if (drag.kind === "duration") {
-      scaleClipDuration(drag.owner, drag.startTimes, drag.startEdge, deltaTime);
+      scaleClipDuration(drag.owner, drag.startTimes, drag.startEdge, delta);
       return;
     }
 
     if (drag.kind === "clip") {
-      shiftClip(drag.owner, drag.startTimes, drag.startEdge, deltaTime);
+      shiftClip(drag.owner, drag.startTimes, drag.startEdge, delta, drag.startClips);
       return;
     }
 
     if (drag.kind === "trimStart") {
-      trimClipStart(drag.owner, drag.startTimes, drag.startEdge, deltaTime);
+      trimClipStart(drag.owner, drag.startTimes, drag.startEdge, delta);
       return;
     }
 
-    moveClipKeyframe(drag.owner, drag.startTimes, drag.index, drag.startEdge, deltaTime, drag.endEdge);
+    moveClipKeyframe(drag.owner, drag.startTimes, drag.index, drag.startEdge, delta, drag.endEdge);
   }
 
   function handleTimeDragEnd(event: ReactPointerEvent<HTMLElement>) {
@@ -1070,6 +1110,7 @@ export function TimelinePanel() {
     if (!drag || drag.pointerId !== event.pointerId) return;
 
     timeDragRef.current = null;
+    hideSnapIndicator();
     document.body.classList.remove("is-timeline-dragging");
 
     try {
@@ -1097,6 +1138,138 @@ export function TimelinePanel() {
     };
   }
 
+  type TimeDragGesture = NonNullable<typeof timeDragRef.current>;
+
+  /**
+   * 收集拖拽时可吸附的目标时刻：同轨道（同角色 / 同相机）其它片段的边缘 + 播放头。
+   * 过滤掉被拖元素自身当前的边缘 / 关键帧时刻，避免「吸回原处」导致无法小幅移动。
+   */
+  function buildSnapTargets(drag: TimeDragGesture): number[] {
+    const targets: number[] = [playhead];
+    const { owner } = drag;
+    if (owner.kind === "motionClip") {
+      const obj = project.objects.find((o) => o.id === owner.objectId);
+      for (const c of obj?.characterRig?.motionClips ?? []) {
+        if (c.id === owner.clipId) continue;
+        targets.push(c.start);
+        if (Number.isFinite(c.end)) targets.push(c.end);
+      }
+    } else if (owner.kind === "trajectory") {
+      const track = project.timeline.tracks.find((t) => t.objectId === owner.objectId);
+      for (const k of track?.keyframes ?? []) {
+        if (k.id === owner.pointId) continue;
+        targets.push(k.time);
+      }
+    } else if (owner.kind === "camera") {
+      const track = project.timeline.cameraTracks.find((t) => t.cameraId === owner.cameraId);
+      for (const k of track?.keyframes ?? []) targets.push(k.time);
+    } else if (owner.kind === "motion") {
+      const obj = project.objects.find((o) => o.id === owner.objectId);
+      if (obj) {
+        const start = getMotionStartTime(obj, duration);
+        const end = getMotionEndTime(obj, duration, start);
+        targets.push(start, end);
+      }
+    }
+
+    const selfTimes: number[] = [];
+    if (drag.kind === "clip") selfTimes.push(drag.startEdge, drag.endEdge);
+    else if (drag.kind === "trimStart") selfTimes.push(drag.startEdge);
+    else if (drag.kind === "duration") selfTimes.push(drag.endEdge);
+    else if (drag.kind === "point") {
+      const t = drag.startTimes[drag.index];
+      if (typeof t === "number") selfTimes.push(t);
+    }
+    return targets.filter((tt) => !selfTimes.some((s) => Math.abs(tt - s) < 1e-6));
+  }
+
+  /**
+   * 收集「网格类」吸附目标：整帧边界（k/fps）+ 刻度网格主刻度线（与车道里画出的竖网格线一致）。
+   * 这是一组「静态基准线」，和动态的同轨片段边缘 / 播放头互补：离后者近时优先吸到后者
+   * （保留原有磁性对齐，可对齐到非整帧位置），否则吸到最近的整帧 / 刻度线。
+   */
+  function buildGridSnapTargets(): number[] {
+    const targets: number[] = [];
+    // 刻度网格：主刻度线（与车道背景的竖网格线一致），便于吸附对齐到可见网格
+    for (const tick of getTimelineRulerTicks(duration)) {
+      targets.push(tick.value);
+    }
+    // 整帧：每帧边界（k/fps），视频按帧导出，关键帧落在整帧上更自然
+    const frameCount = Math.floor(duration * fps + 1e-6);
+    for (let k = 0; k <= frameCount; k += 1) {
+      const tick = k / fps;
+      if (tick <= duration + 1e-6) targets.push(tick);
+    }
+    return targets;
+  }
+
+  /**
+   * 把候选时刻吸附到最近的目标（在阈值内），否则原样返回。
+   */
+  function snapTimeToTargets(candidate: number, targets: number[], thresholdSec: number): number {
+    let best = candidate;
+    let bestDist = thresholdSec;
+    for (const t of targets) {
+      const d = Math.abs(candidate - t);
+      if (d < bestDist) {
+        bestDist = d;
+        best = t;
+      }
+    }
+    return best;
+  }
+
+  /**
+   * 根据拖拽手势与原始位移算出「吸附后的位移」以及被吸附到的时刻（未吸附则为 null）。
+   * 条本体 / 左端把手吸附起点；右端把手吸附终点；关键帧吸附其自身时刻。
+   */
+  function computeSnappedDelta(drag: TimeDragGesture, rawDelta: number): { delta: number; snappedTime: number | null } {
+    const thresholdSec = SNAP_THRESHOLD_PX * drag.secondsPerPixel;
+    let candidate: number;
+    let base: number;
+    if (drag.kind === "clip" || drag.kind === "trimStart") {
+      candidate = drag.startEdge + rawDelta;
+      base = drag.startEdge;
+    } else if (drag.kind === "duration") {
+      candidate = drag.endEdge + rawDelta;
+      base = drag.endEdge;
+    } else {
+      const t = drag.startTimes[drag.index] ?? 0;
+      candidate = t + rawDelta;
+      base = t;
+    }
+    // 第一阶段：吸附到同轨其它片段边缘 / 播放头（保留原有磁性对齐，可对齐到非整帧位置）。
+    const primarySnapped = snapTimeToTargets(candidate, buildSnapTargets(drag), thresholdSec);
+    let snapped = primarySnapped;
+    let didSnap = Math.abs(snapped - candidate) > 1e-6;
+    // 第二阶段：未吸到片段边缘 / 播放头时，再吸附到整帧 / 刻度网格（对齐到可见网格与帧边界）。
+    if (!didSnap) {
+      const gridSnapped = snapTimeToTargets(candidate, buildGridSnapTargets(), thresholdSec);
+      if (Math.abs(gridSnapped - candidate) > 1e-6) {
+        snapped = gridSnapped;
+        didSnap = true;
+      }
+    }
+    return { delta: snapped - base, snappedTime: didSnap ? snapped : null };
+  }
+
+  /** 显示 / 隐藏吸附参考线（直接改样式，不触发 React 重绘） */
+  function showSnapIndicator(time: number | null) {
+    const el = snapIndicatorRef.current;
+    if (!el) return;
+    if (time === null || duration <= 0) {
+      el.classList.remove("is-visible");
+      return;
+    }
+    const percent = Math.min(100, Math.max(0, (time / duration) * 100));
+    el.style.left = `${percent}%`;
+    el.classList.add("is-visible");
+  }
+
+  function hideSnapIndicator() {
+    snapIndicatorRef.current?.classList.remove("is-visible");
+  }
+
   /** 时长把手支持键盘微调（左右方向键 ±0.1s，按住 Shift ±0.5s） */
   function handleTimeHandleKeyDown(
     event: ReactKeyboardEvent<HTMLElement>,
@@ -2076,6 +2249,8 @@ export function TimelinePanel() {
             <div className="timeline-playhead" style={{ left: `${playheadPercent}%` }}>
               <span className="timeline-playhead-knob" />
             </div>
+            {/* 吸附参考线：拖动片段 / 关键帧时，边缘吸到其它片段边缘或播放头处显示 */}
+            <div className="timeline-snap-indicator" ref={snapIndicatorRef} />
           </div>
         </div>
       </div>
diff --git a/src/editor/runtime/CharacterModel.test.tsx b/src/editor/runtime/CharacterModel.test.tsx
index ce10481..dd17f21 100644
--- a/src/editor/runtime/CharacterModel.test.tsx
+++ b/src/editor/runtime/CharacterModel.test.tsx
@@ -3,14 +3,14 @@ import { vi } from "vitest";
 import { CharacterModel } from "./CharacterModel";
 
 vi.mock("./UE4MannequinModel", () => ({
-  UE4MannequinModel: ({ bodyType }: { bodyType?: string }) => (
-    <div data-body-type={bodyType} data-testid="mock-ue4-mannequin" />
+  UE4MannequinModel: ({ bodyType, rigState }: { bodyType?: string; rigState?: { motion?: { kind?: string } } }) => (
+    <div data-body-type={bodyType} data-motion-kind={rigState?.motion?.kind} data-testid="mock-ue4-mannequin" />
   ),
 }));
 
 vi.mock("./PrimitiveMannequin", () => ({
-  PrimitiveMannequin: ({ bodyType }: { bodyType?: string }) => (
-    <div data-body-type={bodyType} data-testid="mock-procedural-mannequin" />
+  PrimitiveMannequin: ({ bodyType, rigState }: { bodyType?: string; rigState?: { motion?: { kind?: string } } }) => (
+    <div data-body-type={bodyType} data-motion-kind={rigState?.motion?.kind} data-testid="mock-procedural-mannequin" />
   ),
 }));
 
@@ -47,3 +47,64 @@ it("keeps the procedural mannequin fallback for non-UE4 rigs", () => {
   expect(screen.getByTestId("mock-procedural-mannequin")).toHaveAttribute("data-body-type", "chibi");
   expect(screen.queryByTestId("mock-ue4-mannequin")).not.toBeInTheDocument();
 });
+
+it("holds the character static when the clip sequence has no clip at the current time", () => {
+  const { rerender } = render(
+    <CharacterModel
+      bodyType="female"
+      rigState={{
+        rigType: "ue4-mannequin",
+        posePresetId: "stand",
+        motion: { kind: "walk", speed: 1, amplitude: 1, enabled: true },
+        controls: {},
+      }}
+      motionTime={3}
+      motionClips={[
+        { id: "a", kind: "walk", speed: 1, amplitude: 1, enabled: true, start: 0, end: 2 },
+        { id: "b", kind: "run", speed: 1, amplitude: 1, enabled: true, start: 5, end: 8 },
+      ]}
+      duration={10}
+    />
+  );
+
+  // t=3 落在两个片段之间的空隙 → 静止（none），而非沿用默认 walk
+  expect(screen.getByTestId("mock-ue4-mannequin")).toHaveAttribute("data-motion-kind", "none");
+
+  // t=6 落在 run 片段内 → 使用 run
+  rerender(
+    <CharacterModel
+      bodyType="female"
+      rigState={{
+        rigType: "ue4-mannequin",
+        posePresetId: "stand",
+        motion: { kind: "walk", speed: 1, amplitude: 1, enabled: true },
+        controls: {},
+      }}
+      motionTime={6}
+      motionClips={[
+        { id: "a", kind: "walk", speed: 1, amplitude: 1, enabled: true, start: 0, end: 2 },
+        { id: "b", kind: "run", speed: 1, amplitude: 1, enabled: true, start: 5, end: 8 },
+      ]}
+      duration={10}
+    />
+  );
+  expect(screen.getByTestId("mock-ue4-mannequin")).toHaveAttribute("data-motion-kind", "run");
+});
+
+it("keeps the legacy single-motion behavior when no clip sequence is provided", () => {
+  render(
+    <CharacterModel
+      bodyType="female"
+      rigState={{
+        rigType: "ue4-mannequin",
+        posePresetId: "stand",
+        motion: { kind: "walk", speed: 1, amplitude: 1, enabled: true },
+        controls: {},
+      }}
+      motionTime={3}
+      duration={10}
+    />
+  );
+
+  expect(screen.getByTestId("mock-ue4-mannequin")).toHaveAttribute("data-motion-kind", "walk");
+});
diff --git a/src/editor/runtime/CharacterModel.tsx b/src/editor/runtime/CharacterModel.tsx
index 780bc71..55b25c3 100644
--- a/src/editor/runtime/CharacterModel.tsx
+++ b/src/editor/runtime/CharacterModel.tsx
@@ -1,5 +1,5 @@
 import { Component, type ReactNode } from "react";
-import type { CharacterRigState, MotionClip } from "../schema/directorProject";
+import type { CharacterMotionState, CharacterRigState, MotionClip } from "../schema/directorProject";
 import { PrimitiveMannequin } from "./PrimitiveMannequin";
 import { UE4MannequinModel } from "./UE4MannequinModel";
 import { GltfCharacterModel } from "./GltfCharacterModel";
@@ -47,13 +47,20 @@ class CharacterModelBoundary extends Component<
 
 export function CharacterModel({ bodyType, color, onLabelAnchorYChange, rigState, motionTime, characterId, motionStartTime, motionEndTime, modelAssetUrl, motionClips, duration }: CharacterModelProps) {
   // 动作序列：按当前播放时间取出应生效的片段（后段覆盖前段），用它覆盖单一 motion 字段。
-  // 无片段 / 时间不在任何片段内 → 回退到旧的单一段落（rigState.motion + motionStartTime/EndTime）。
+  // 处于时间轴片段序列模式、但当前时间没有任何片段覆盖时 → 人物保持静止（none），而非沿用默认动作。
+  // 仅在「未启用片段序列」的 legacy 模式下，才回退到旧的单一段落（rigState.motion + motionStartTime/EndTime）。
+  const usingSequence = Array.isArray(motionClips);
   const activeClip = getActiveMotionClipAtTime(motionClips, motionTime ?? 0, duration);
-  const resolvedRigState: CharacterRigState | undefined = activeClip && rigState
-    ? { ...rigState, motion: activeClip }
-    : rigState;
-  const resolvedStart = activeClip ? activeClip.start : motionStartTime;
-  const resolvedEnd = activeClip ? resolveMotionClipEnd(activeClip, duration) : motionEndTime;
+  const staticInSequence = usingSequence && !activeClip;
+  const STATIC_MOTION: CharacterMotionState = { kind: "none", speed: 1, amplitude: 1, enabled: true };
+  const resolvedRigState: CharacterRigState | undefined =
+    activeClip && rigState
+      ? { ...rigState, motion: activeClip }
+      : staticInSequence && rigState
+        ? { ...rigState, motion: STATIC_MOTION }
+        : rigState;
+  const resolvedStart = activeClip ? activeClip.start : staticInSequence ? motionTime : motionStartTime;
+  const resolvedEnd = activeClip ? resolveMotionClipEnd(activeClip, duration) : staticInSequence ? motionTime : motionEndTime;
 
   const fallback = <PrimitiveMannequin bodyType={bodyType} color={color} rigState={resolvedRigState} motionTime={motionTime} characterId={characterId} motionStartTime={resolvedStart} motionEndTime={resolvedEnd} />;
 
diff --git a/src/editor/store/directorStore.motionClip.test.ts b/src/editor/store/directorStore.motionClip.test.ts
index 3a4606d..ac135b9 100644
--- a/src/editor/store/directorStore.motionClip.test.ts
+++ b/src/editor/store/directorStore.motionClip.test.ts
@@ -15,7 +15,7 @@ beforeEach(() => {
   });
 });
 
-describe("动作片段拖动不重叠（可交换位置）", () => {
+describe("动作片段拖动不重叠（重叠时紧贴到就近一侧）", () => {
   function setupTwoClips() {
     const s = useDirectorStore.getState();
     // 给足够长的时间轴，避免片段被默认较短的时长截断，干扰重叠推挤逻辑的验证
@@ -27,32 +27,206 @@ describe("动作片段拖动不重叠（可交换位置）", () => {
     return { a: clips[0].id, b: clips[1].id };
   }
 
-  it("整段右移穿过另一段：两者不重叠，被压片段被推到左侧", () => {
+  it("整段右移穿过另一段：被拖片段紧贴放在被压片段之后（首尾相接、不重叠）", () => {
     const { a, b } = setupTwoClips();
     useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 6, 11, 0);
     const clipA = getClips("char_default_a").find((c) => c.id === a)!;
     const clipB = getClips("char_default_a").find((c) => c.id === b)!;
-    expect(clipA.start).toBe(6);
-    expect(clipB.end).toBeLessThanOrEqual(clipA.start);
-    expect(clipB.start).toBeGreaterThanOrEqual(0);
+    expect(clipA.start).toBe(clipB.end);
+    expect(clipA.end).toBeLessThanOrEqual(30);
   });
 
-  it("整段左移穿过另一段：被压片段被推到右侧", () => {
+  it("整段左移穿过另一段：被拖片段贴到被压片段就近一侧、不重叠", () => {
     const { a, b } = setupTwoClips();
     useDirectorStore.getState().updateMotionClipTime("char_default_a", b, 0, 4, 5);
     const clipA = getClips("char_default_a").find((c) => c.id === a)!;
     const clipB = getClips("char_default_a").find((c) => c.id === b)!;
-    expect(clipB.start).toBe(0);
-    expect(clipA.start).toBeGreaterThanOrEqual(clipB.end);
+    // 自身左端没有空间，于是贴到 A 之后；两段不重叠。
+    expect(clipA.end).toBeLessThanOrEqual(clipB.start);
   });
 
-  it("右端把手扩张进入另一段：被压片段被挤到右侧", () => {
+  it("右端把手扩张进入另一段：整段被推到被压片段之后", () => {
     const { a, b } = setupTwoClips();
-    // 拖动 A 的右端把手从 5 扩张到 8（进入 B[5,10]），起点不变 → 推 B 到右侧
+    // 拖动 A 的右端把手从 5 扩张到 8（进入 B[5,10]），与 B 重叠 → 整段贴到 B 之后。
     useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 0, 8, 0);
     const clipA = getClips("char_default_a").find((c) => c.id === a)!;
     const clipB = getClips("char_default_a").find((c) => c.id === b)!;
-    expect(clipA.end).toBe(8);
-    expect(clipB.start).toBeGreaterThanOrEqual(clipA.end);
+    expect(clipA.start).toBe(clipB.end);
+    expect(clipA.end).toBeLessThanOrEqual(30);
+  });
+
+  it("轻微重叠：被拖片段贴到就近一侧、不与任何片段重叠", () => {
+    const { a, b } = setupTwoClips();
+    // A[0,5] 右移到 [2,7]，与 B[5,10] 轻微重叠 → 贴到 B 之前（回到 [0,5]）。
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 2, 7, 0);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipA.start).toBe(0);
+    expect(clipA.end).toBeLessThanOrEqual(clipB.start);
+  });
+
+  it("有限片段拖入「到末尾」的无限长片段：贴到其之前、不重叠", () => {
+    const s = useDirectorStore.getState();
+    s.setTimelineDuration(30);
+    // A 有限 [0,5]，B 是「到末尾」无限长 [5,∞)（默认 addMotionClip 的终点就是这个）
+    s.addMotionClip("char_default_a", { kind: "walk", start: 0, end: 5 });
+    s.addMotionClip("char_default_a", { kind: "walk", start: 5 });
+    const clips = getClips("char_default_a");
+    const a = clips[0].id;
+    const b = clips[1].id;
+    // 把 A 右拖到 [8,13]，压在无限长 B 上 → 应贴回 B 之前 [0,5]，而不是被吸到末尾重叠
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 8, 13, 0);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipA.end).toBeLessThanOrEqual(clipB.start);
+    expect(clipA.start).toBe(0);
+  });
+
+  it("无限长片段拖入有限片段：只能贴到被压片段之后、不重叠", () => {
+    const s = useDirectorStore.getState();
+    s.setTimelineDuration(30);
+    // A 有限 [0,5]，B 无限长 [5,∞)
+    s.addMotionClip("char_default_a", { kind: "walk", start: 0, end: 5 });
+    s.addMotionClip("char_default_a", { kind: "walk", start: 5 });
+    const clips = getClips("char_default_a");
+    const a = clips[0].id;
+    const b = clips[1].id;
+    // 把无限长的 B 左拖到起点 2（变成 [2,∞)），压在 A 上 → 应贴到 A 之后 [5,∞)
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", b, 2, Number.POSITIVE_INFINITY, 5);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipB.start).toBe(clipA.end);
+    expect(clipB.end).toBe(Number.POSITIVE_INFINITY);
+  });
+
+  it("多段相邻：被拖片段穿过中间两段仍落稳、全程不重叠", () => {
+    const s = useDirectorStore.getState();
+    s.setTimelineDuration(30);
+    s.addMotionClip("char_default_a", { kind: "walk", start: 0, end: 5 });
+    s.addMotionClip("char_default_a", { kind: "walk", start: 5, end: 10 });
+    s.addMotionClip("char_default_a", { kind: "walk", start: 10, end: 15 });
+    const clips = getClips("char_default_a");
+    const a = clips[0].id;
+    // 把开头这段拖到 [7,12]，同时压住中段与末段 → 迭代解析后应贴到末段之后 [15,20]
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 7, 12, 0);
+    const all = getClips("char_default_a");
+    for (let i = 0; i < all.length; i += 1) {
+      for (let j = i + 1; j < all.length; j += 1) {
+        const x = all[i];
+        const y = all[j];
+        const overlap = x.start < y.end && y.start < x.end;
+        expect(overlap).toBe(false);
+      }
+    }
+    const clipA = all.find((c) => c.id === a)!;
+    expect(clipA.start).toBe(15);
+  });
+});
+
+describe("动作片段拖动换位（越过邻居即交换位置、可重排）", () => {
+  function setupConnected(durations: Array<[number, number]>) {
+    const s = useDirectorStore.getState();
+    s.setTimelineDuration(30);
+    const ids: string[] = [];
+    for (const [start, end] of durations) {
+      s.addMotionClip("char_default_a", { kind: "walk", start, end });
+      const clips = getClips("char_default_a");
+      ids.push(clips[clips.length - 1].id);
+    }
+    return ids;
+  }
+
+  it("相邻等长两段：拖右越过邻居中点后才交换、无重叠", () => {
+    const [a, b] = setupConnected([
+      [0, 5],
+      [5, 10],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // A[0,5] 右拖到 [8,13]，越过 B 的中点(7.5) → 交换：A 到 [5,10]，B 到 [0,5]
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 8, 13, 0, original);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipA.start).toBe(5);
+    expect(clipA.end).toBe(10);
+    expect(clipB.start).toBe(0);
+    expect(clipB.end).toBe(5);
+  });
+
+  it("相邻等长两段：只轻微重叠（未过半）不交换、贴回原处", () => {
+    const [a, b] = setupConnected([
+      [0, 5],
+      [5, 10],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // A[0,5] 只拖到 [6,11]，未越过 B 的中点(7.5) → 不交换，应贴回 [0,5]
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 6, 11, 0, original);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    expect(clipA.start).toBe(0);
+    expect(clipA.end).toBe(5);
+  });
+
+  it("相邻等长两段：从右往左拖越过邻居中点后同样交换", () => {
+    const [a, b] = setupConnected([
+      [0, 5],
+      [5, 10],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // B[5,10] 左拖到 [2,7]，越过 A 的中点(2.5) → 交换：B 到 [0,5]，A 到 [5,10]
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", b, 2, 7, 5, original);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipB.start).toBe(0);
+    expect(clipA.start).toBe(5);
+  });
+
+  it("不等长两段：越过较长邻居中点才交换，各自保留时长、不重叠", () => {
+    const [a, b] = setupConnected([
+      [0, 5],
+      [5, 12],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // A 右拖到 [9,14]，越过 B 的中点(8.5)才交换：B 向左平移、A 接在后面，仍不重叠
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 9, 14, 0, original);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    const overlap = clipA.start < clipB.end && clipB.start < clipA.end;
+    expect(overlap).toBe(false);
+    // A 落在 B 之后（已被换位到末尾）
+    expect(clipA.start).toBeGreaterThanOrEqual(clipB.end - 1e-6);
+  });
+
+  it("三段：把开头那段一路拖过中间两段中点，重排到末尾、全程不重叠", () => {
+    const [a, b, c] = setupConnected([
+      [0, 5],
+      [5, 10],
+      [10, 15],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // A 拖到 [13,18]，越过 B(7.5) 与 C(12.5) 的中点 → 排到末尾
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 13, 18, 0, original);
+    const all = getClips("char_default_a");
+    for (let i = 0; i < all.length; i += 1) {
+      for (let j = i + 1; j < all.length; j += 1) {
+        const x = all[i];
+        const y = all[j];
+        expect(x.start < y.end && y.start < x.end).toBe(false);
+      }
+    }
+    const clipA = all.find((c) => c.id === a)!;
+    expect(clipA.start).toBe(10);
+  });
+
+  it("没压到任何片段时自由移动，其余片段位置不变", () => {
+    const [a, b] = setupConnected([
+      [0, 5],
+      [10, 15],
+    ]);
+    const original = getClips("char_default_a").map((c) => ({ ...c }));
+    // A 拖到 [20,25]（落在 B 右边的空档），不应触发换位
+    useDirectorStore.getState().updateMotionClipTime("char_default_a", a, 20, 25, 0, original);
+    const clipA = getClips("char_default_a").find((c) => c.id === a)!;
+    const clipB = getClips("char_default_a").find((c) => c.id === b)!;
+    expect(clipA.start).toBe(20);
+    expect(clipB.start).toBe(10);
   });
 });
diff --git a/src/editor/store/directorStore.ts b/src/editor/store/directorStore.ts
index 1db9054..e109978 100644
--- a/src/editor/store/directorStore.ts
+++ b/src/editor/store/directorStore.ts
@@ -194,8 +194,17 @@ export interface DirectorActions {
     clipId: string,
     patch: Partial<Pick<MotionClip, "kind" | "speed" | "amplitude" | "enabled">>
   ) => void;
-  /** 整体平移 / 缩放某个动作片段的时间区间（拖拽条本体或两端把手时写入）。 */
-  updateMotionClipTime: (objectId: string, clipId: string, start: number, end: number, oldStart?: number) => void;
+  /** 整体平移 / 缩放某个动作片段的时间区间（拖拽条本体或两端把手时写入）。
+   *  originalClips 传「拖拽开始时该角色的全部动作片段」即可开启「拖动换位」：被拖片段越过谁就与谁交换位置；
+   *  不传则退回原来的「紧贴就近一侧」解析（修修剪剪、程序化写入等场景）。 */
+  updateMotionClipTime: (
+    objectId: string,
+    clipId: string,
+    start: number,
+    end: number,
+    oldStart?: number,
+    originalClips?: MotionClip[]
+  ) => void;
   /** 删除某个动作片段。 */
   removeMotionClip: (objectId: string, clipId: string) => void;
   /** 选中 / 取消选中某个动作片段；clipId 为 null 表示取消。 */
@@ -1563,6 +1572,174 @@ function trimUndoStack(stack: DirectorState[]) {
   return stack.length > UNDO_STACK_LIMIT ? stack.slice(stack.length - UNDO_STACK_LIMIT) : stack;
 }
 
+/**
+ * 动作轨道不允许重叠：把 clipId 这段紧贴到与其重叠片段的「最近一侧」（之前 / 之后），
+ * 迭代处理直到与所有片段都不重叠。正确处理无限长片段（片段终点默认到时间轴末尾）：
+ * - 被拖片段无限长：只能放在被压片段之后（否则必然覆盖它）；
+ * - 被压片段无限长：被拖片段有限时长时放在其之前（终点贴被压片段起点）。
+ */
+function resolveMotionClipOverlap(
+  clips: MotionClip[],
+  clipId: string,
+  duration: number,
+  desiredStartOverride?: number,
+  desiredEndOverride?: number
+): MotionClip[] {
+  // 若给了期望区间，先一次性把被拖片段放到该位置，再迭代解决与邻居的级联重叠
+  let result = clips;
+  if (desiredStartOverride !== undefined && desiredEndOverride !== undefined) {
+    result = result.map((c) =>
+      c.id === clipId ? { ...c, start: desiredStartOverride, end: desiredEndOverride } : c
+    );
+  }
+  const maxIter = result.length + 2;
+  for (let iter = 0; iter < maxIter; iter += 1) {
+    const dragged = result.find((c) => c.id === clipId);
+    if (!dragged) break;
+    const ov = result.find((c) => c.id !== clipId && c.start < dragged.end && c.end > dragged.start);
+    if (!ov) break;
+    const dFinite = Number.isFinite(dragged.end);
+    const dSpan = dFinite ? dragged.end - dragged.start : duration - dragged.start;
+    const dCenter = dragged.start + dSpan / 2;
+    const oFinite = Number.isFinite(ov.end);
+    const oCenter = ov.start + (oFinite ? (ov.end - ov.start) / 2 : (duration - ov.start) / 2);
+    let ns: number;
+    if (!dFinite) {
+      // 无限长被拖片段只能放在被压片段之后，否则必然覆盖它
+      ns = oFinite ? ov.end : 0;
+    } else {
+      const afterStart = oFinite ? ov.end : duration - dSpan;
+      const afterValid = oFinite && afterStart + dSpan <= duration;
+      const beforeStart = ov.start - dSpan;
+      const beforeValid = beforeStart >= 0;
+      const preferAfter = dCenter >= oCenter;
+      if (preferAfter) ns = afterValid ? afterStart : beforeValid ? beforeStart : Math.max(0, afterStart);
+      else ns = beforeValid ? beforeStart : afterValid ? afterStart : 0;
+    }
+    const ne = dFinite ? ns + dSpan : Number.POSITIVE_INFINITY;
+    result = result.map((c) => (c.id === clipId ? { ...c, start: ns, end: ne } : c));
+  }
+  return result;
+}
+
+/**
+ * 在「不重叠」前提下，把被拖片段与同轨道邻居换位：拖动越过谁就与谁交换位置（被跨过的邻居整体平移，
+ * 各自时长不变、不缩放）。换位阈值取「被拖片段前缘越过邻居中点（过半）」，避免刚碰到边界就跳位；
+ * 未过半时不跳到另一侧，而是挡在所压邻居的当前侧边界上。基于当前布局计算，因此换位后可再拖回。
+ * 任一片段无限长则放弃换位（无限长片段无法塞进某个槽），交回上层走通用解析。
+ */
+function resolveMotionClipReorder(
+  clips: MotionClip[],
+  clipId: string,
+  desiredStart: number,
+  desiredEnd: number,
+  originalClips: MotionClip[],
+  duration: number
+): MotionClip[] | null {
+  const dragged = clips.find((c) => c.id === clipId);
+  if (!dragged || !Number.isFinite(desiredEnd)) return null;
+  const length = desiredEnd - desiredStart;
+
+  const cur = [...clips].sort((a, b) => a.start - b.start);
+  if (cur.some((c) => !Number.isFinite(c.end))) return null;
+  const i = cur.findIndex((c) => c.id === clipId);
+  if (i < 0) return null;
+
+  const n = cur.length;
+  const midpoint = (c: MotionClip) => (c.start + c.end) / 2;
+  // 阈值：被拖片段的「前缘」(desiredStart) 越过邻居「中点」（过半）才交换。
+  // 右移看右侧邻居、左移看左侧邻居，越过谁就与谁交换。
+  const rightPassed = cur.filter(
+    (c) => c.id !== clipId && c.start > cur[i].start && desiredStart > midpoint(c)
+  ).length;
+  const leftPassed = cur.filter(
+    (c) => c.id !== clipId && c.start < cur[i].start && desiredStart < midpoint(c)
+  ).length;
+  const delta = desiredStart - cur[i].start; // 当前位置 → 期望位置：判断拖拽方向
+  let j = delta >= 0 ? i + rightPassed : i - leftPassed;
+  j = Math.max(0, Math.min(j, n - 1));
+
+  if (j === i) {
+    // 未过半：挡在所压邻居的当前侧、不跳到另一侧（轻微重叠即弹到对面的手感不要）。
+    const others = cur.filter((c) => c.id !== clipId);
+    const overlap = others.filter((o) => o.start < desiredEnd && o.end > desiredStart);
+    if (overlap.length === 0) return clips;
+    let start: number;
+    if (delta >= 0) {
+      const right =
+        overlap.filter((o) => o.start >= cur[i].start).sort((a, b) => a.start - b.start)[0] ??
+        overlap.slice().sort((a, b) => a.start - b.start)[0];
+      start = right.start - length;
+    } else {
+      const left =
+        overlap.filter((o) => o.end <= cur[i].start).sort((a, b) => b.end - a.end)[0] ??
+        overlap.slice().sort((a, b) => b.end - a.end)[0];
+      start = left.end;
+    }
+    start = Math.max(0, Math.min(start, duration - length));
+    return clips.map((c) => (c.id === clipId ? { ...c, start, end: start + length } : c));
+  }
+
+  // 受影响片段（被跨过的邻居）整体平移、保留各自时长；它们在段内的顺序，以及被拖片段在段的哪一端，取决于方向。
+  const segClips: MotionClip[] =
+    j > i ? [...cur.slice(i + 1, j + 1), dragged] : [dragged, ...cur.slice(j, i)];
+  // 段的左边界：紧贴被拖片段当前的左邻居（右移）或段内首个被跨片段当前的左邻居（左移）之后。
+  const segLeft = j > i ? (i > 0 ? cur[i - 1].end : 0) : j > 0 ? cur[j - 1].end : 0;
+
+  let pos = segLeft;
+  const newStart = new Map<string, number>();
+  for (const c of segClips) {
+    newStart.set(c.id, pos);
+    pos += c.end - c.start;
+  }
+  const draggedEnd = newStart.get(clipId)! + length;
+
+  // 兜底：与段外邻居 / 时间轴边界重叠则放弃换位
+  if (draggedEnd > duration + 1e-6) return null;
+  if (j > i && j + 1 < n && draggedEnd > cur[j + 1].start + 1e-6) return null;
+  if (j < i && i + 1 < n && draggedEnd > cur[i + 1].start + 1e-6) return null;
+  if (segLeft < -1e-6) return null;
+
+  const curLength = (id: string) => {
+    const o = cur.find((c) => c.id === id)!;
+    return o.end - o.start;
+  };
+  return clips.map((c) => {
+    if (!newStart.has(c.id)) return c;
+    const s = newStart.get(c.id)!;
+    const len = c.id === clipId ? length : curLength(c.id);
+    return { ...c, start: s, end: s + len };
+  });
+}
+
+/**
+ * 决定被拖片段（当前 clips 里还是上一帧的位置）放到期望区间后的最终布局：
+ * - 期望区间没压到任何片段 → 自由移动，直接落到期望区间；
+ * - 压到了且有拖拽起始布局 → 尝试「过半才交换」的换位；
+ * - 否则（修修剪剪 / 无限长兜底）→ 退回「紧贴就近一侧」的通用解析。
+ */
+function resolveMotionClipArrangement(
+  clips: MotionClip[],
+  clipId: string,
+  desiredStart: number,
+  desiredEnd: number,
+  duration: number,
+  originalClips?: MotionClip[]
+): MotionClip[] {
+  const dragged = clips.find((c) => c.id === clipId);
+  if (!dragged) return clips;
+  // 用「期望区间」判断是否与其它片段冲突（clips 里被拖片段仍是上一帧位置）
+  const desiredOverlaps = clips.some((c) => c.id !== clipId && c.start < desiredEnd && c.end > desiredStart);
+  if (!desiredOverlaps) {
+    return clips.map((c) => (c.id === clipId ? { ...c, start: desiredStart, end: desiredEnd } : c));
+  }
+  if (originalClips) {
+    const reordered = resolveMotionClipReorder(clips, clipId, desiredStart, desiredEnd, originalClips, duration);
+    if (reordered) return reordered;
+  }
+  return resolveMotionClipOverlap(clips, clipId, duration, desiredStart, desiredEnd);
+}
+
 export const useDirectorStore = create<DirectorStore>((set, get) => {
   const initialRuntimeState = createRuntimeStateFromPersistedState(
     createInitialDirectorState({ includePersistedLocalAssets: true, includePersistedScene: true })
@@ -2093,9 +2270,11 @@ export const useDirectorStore = create<DirectorStore>((set, get) => {
               const nextClips = existing.map((clip) =>
                 clip.end === Number.POSITIVE_INFINITY && clip.start < start ? { ...clip, end: start } : clip
               );
+              const merged = [...nextClips, newClip];
+              // 动作轨道不允许重叠：若新片段与已有片段重叠，紧贴到就近一侧。
               return {
                 ...item,
-                characterRig: { ...item.characterRig, motionClips: [...nextClips, newClip] },
+                characterRig: { ...item.characterRig, motionClips: resolveMotionClipOverlap(merged, newClip.id, duration) },
               };
             }),
           },
@@ -2120,7 +2299,7 @@ export const useDirectorStore = create<DirectorStore>((set, get) => {
           }),
         },
       })),
-    updateMotionClipTime: (objectId, clipId, start, end, oldStart) =>
+    updateMotionClipTime: (objectId, clipId, start, end, oldStart, originalClips) =>
       commitMutation((state) => {
         const duration = state.project.timeline.duration;
         // 先把起点限制在时间轴内，再保证终点不早于起点（避免拖出时间轴后区间倒挂）。
@@ -2128,50 +2307,23 @@ export const useDirectorStore = create<DirectorStore>((set, get) => {
         const clampedEnd = Number.isFinite(end)
           ? Math.min(Math.max(end, clampedStart + MOTION_CLIP_MIN_DURATION), duration)
           : Number.POSITIVE_INFINITY;
-        // 拖拽开始前的起点，用于判断拖动方向（右移 / 左移）。
-        const oldS = oldStart !== undefined && Number.isFinite(oldStart) ? Math.max(oldStart, 0) : null;
         return {
           ...state,
           project: {
             ...state.project,
             objects: updateObjectById(state.project.objects, objectId, (item) => {
               if (!item.characterRig?.motionClips) return item;
-              let clips = item.characterRig.motionClips.map((clip) =>
-                clip.id === clipId ? { ...clip, start: clampedStart, end: clampedEnd } : clip
+              // 被拖片段在 clips 里仍是上一帧的位置；依据期望区间决定最终布局：
+              // 没压到任何片段就自由移动，压到了就尝试「过半才交换」的换位（originalClips 提供拖拽起始布局），
+              // 否则退回紧贴就近一侧的解析。
+              const clips = resolveMotionClipArrangement(
+                item.characterRig.motionClips,
+                clipId,
+                clampedStart,
+                clampedEnd,
+                duration,
+                originalClips
               );
-              // 拖动导致与另一片段重叠时，保证不重叠：把被压住的片段「推」到当前片段的另一侧贴边，
-              // 从而自然实现「交换位置」——把一段拖过另一段时，两者互换先后，且全程不重叠。
-              if (oldS !== null) {
-                const overlap = clips.find(
-                  (c) => c.id !== clipId && c.start < clampedEnd && c.end > clampedStart
-                );
-                if (overlap) {
-                  const overlapFinite = Number.isFinite(overlap.end);
-                  const overlapLen = overlapFinite ? overlap.end - overlap.start : 0;
-                  // 起点是否变化：整段平移 / 左端把手会动起点；仅右端把手（终点扩张）起点不动。
-                  const startChanged = Math.abs(clampedStart - oldS) > 1e-6;
-                  if (!startChanged) {
-                    // 仅拖动右端把手（终点向右扩张）：右侧重叠片段被挤到当前片段右侧。
-                    const s = clampedEnd;
-                    const e = overlapFinite
-                      ? Math.min(clampedEnd + overlapLen, duration)
-                      : Number.POSITIVE_INFINITY;
-                    clips = clips.map((c) => (c.id === overlap.id ? { ...c, start: s, end: e } : c));
-                  } else if (clampedStart >= oldS) {
-                    // 向右拖（整段或左端把手右移）：重叠片段推到当前片段左侧（紧贴其左端）。
-                    const s = overlapFinite ? Math.max(0, clampedStart - overlapLen) : 0;
-                    const e = clampedStart;
-                    clips = clips.map((c) => (c.id === overlap.id ? { ...c, start: s, end: e } : c));
-                  } else {
-                    // 向左拖：重叠片段推到当前片段右侧（紧贴其右端，必要时延伸到末尾）。
-                    const s = clampedEnd;
-                    const e = overlapFinite
-                      ? Math.min(clampedEnd + overlapLen, duration)
-                      : Number.POSITIVE_INFINITY;
-                    clips = clips.map((c) => (c.id === overlap.id ? { ...c, start: s, end: e } : c));
-                  }
-                }
-              }
               return {
                 ...item,
                 characterRig: { ...item.characterRig, motionClips: clips },
diff --git a/src/styles/index.css b/src/styles/index.css
index 0274b8a..a9fdbb8 100644
--- a/src/styles/index.css
+++ b/src/styles/index.css
@@ -4144,6 +4144,13 @@ textarea:focus-visible {
   display: flex;
   flex-direction: column;
 }
+/* 轨道之间的分隔线：每条主轨道（物体轨道 / 运镜组 / 角色组）底部加一条清晰的分隔线，
+   方便区分相邻轨道；组内的子轨道仍由各自的 cell 边框分隔。 */
+.timeline-grid-body > .timeline-track,
+.timeline-grid-body > .timeline-camera-track,
+.timeline-grid-body > .timeline-character-track {
+  border-bottom: 1px solid rgb(var(--border-rgb) / 0.5);
+}
 .timeline-track {
   display: grid;
   grid-template-columns: var(--timeline-gutter-width) minmax(0, 1fr);
@@ -4609,6 +4616,23 @@ body.is-timeline-dragging * {
   box-shadow: 0 1px 3px rgb(var(--overlay-rgb) / 0.35);
   transform: translateX(-50%);
 }
+/* 吸附参考线：拖动片段 / 关键帧时，边缘吸到其它片段边缘或播放头处显示的磁吸高亮竖线 */
+.timeline-snap-indicator {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  width: 2px;
+  margin-left: -1px;
+  background: rgb(120 220 255 / 0.9);
+  box-shadow: 0 0 6px rgb(120 220 255 / 0.75);
+  opacity: 0;
+  pointer-events: none;
+  z-index: 5;
+  transition: opacity 0.08s ease-out;
+}
+.timeline-snap-indicator.is-visible {
+  opacity: 1;
+}
 
 /* 关键帧：菱形块 + 悬停/选中时露出删除按钮 */
 .timeline-keyframe {