fix(studio): resolve a panel edit through the lane groups it can see

animIdForProp matched on the parser's whole-tween propertyGroup, which is
undefined for a legacy mixed tween such as {x, opacity}. Such a tween never
matched, so an edit to either property fell through to the selection's
default animation, a different tween than the lane the user is editing.
Resolve through animationLaneGroups, the same per-keyframe helper the
rendered lanes and the reserved row heights already count groups with.

packages/studio/src/player/components/TimelinePropertyLanes.test.tsx

@@ -7,6 +7,7 @@ import { afterEach, describe, expect, it, vi } from "vitest";
 import { TimelineClipDiamonds } from "./TimelineClipDiamonds";
 import {
   getTimelinePropertyLanes,
+  resolveAnimIdForProperty,
   TimelinePropertyLanes,
   type TimelinePropertyLanesProps,
 } from "./TimelinePropertyLanes";
@@ -555,3 +556,49 @@ describe("TimelinePropertyLanes", () => {
     act(() => root.unmount());
   });
 });
+
+describe("resolveAnimIdForProperty", () => {
+  /** A legacy mixed tween: the parser leaves propertyGroup undefined for it. */
+  const mixed = {
+    id: "mixed-1",
+    targetSelector: "#box",
+    method: "to",
+    position: 0,
+    properties: {},
+    keyframes: {
+      keyframes: [
+        { percentage: 0, properties: { x: 0, opacity: 0 } },
+        { percentage: 100, properties: { x: 40, opacity: 1 } },
+      ],
+    },
+  } as unknown as GsapAnimation;
+
+  it("routes both groups of a mixed tween to that tween, not the fallback", () => {
+    expect(mixed.propertyGroup).toBeUndefined();
+
+    expect(resolveAnimIdForProperty("x", [mixed], "fallback")).toBe("mixed-1");
+    expect(resolveAnimIdForProperty("opacity", [mixed], "fallback")).toBe("mixed-1");
+  });
+
+  it("falls back only when no tween animates the property's group", () => {
+    expect(resolveAnimIdForProperty("rotation", [mixed], "fallback")).toBe("fallback");
+    expect(resolveAnimIdForProperty("rotation", [mixed], undefined)).toBe("");
+  });
+
+  it("prefers a single-group tween that owns the lane", () => {
+    const opacityOnly = {
+      ...mixed,
+      id: "opacity-1",
+      propertyGroup: "visual",
+      keyframes: {
+        keyframes: [
+          { percentage: 0, properties: { opacity: 0 } },
+          { percentage: 100, properties: { opacity: 1 } },
+        ],
+      },
+    } as unknown as GsapAnimation;
+
+    expect(resolveAnimIdForProperty("opacity", [opacityOnly, mixed], "fallback")).toBe("opacity-1");
+    expect(resolveAnimIdForProperty("x", [opacityOnly, mixed], "fallback")).toBe("mixed-1");
+  });
+});

packages/studio/src/player/components/TimelinePropertyLanes.tsx

@@ -77,6 +77,28 @@ export function animationLaneGroups(animation: GsapAnimation): PropertyGroupName
   return Array.from(groups);
 }
 
+/**
+ * Which tween a panel edit to `prop` belongs to.
+ *
+ * Matches on the groups the tween's KEYFRAMES animate, not on the parser's
+ * whole-tween `propertyGroup` verdict: that field is undefined for a legacy
+ * mixed tween such as `{ x, opacity }`, so matching it dropped every such
+ * tween and sent the edit to the selection's default animation instead, which
+ * is a different tween than the lane the user is looking at.
+ * {@link animationLaneGroups} is the single owner the rendered lanes count
+ * groups through, so resolving here through the same helper keeps the panel
+ * and the lanes on one answer.
+ */
+export function resolveAnimIdForProperty(
+  prop: string,
+  animations: readonly GsapAnimation[] | undefined,
+  fallbackAnimId: string | undefined,
+): string {
+  const group = classifyPropertyGroup(prop);
+  const groupAnim = animations?.find((a) => animationLaneGroups(a).includes(group));
+  return groupAnim?.id ?? fallbackAnimId ?? "";
+}
+
 /** A tween contributes a property lane when it animates at least one property
  *  on at least one editable keyframe (real or synthesized). */
 export function animationContributesLane(animation: GsapAnimation): boolean {