fix(studio): author every new tween against one element

U3 fixed "add keyframe at playhead" widening a write to every sibling
sharing a class, but wired writeTargetSelector into only two paths. The
same bug was still reachable from the add-animation button, drag, resize,
rotate, gesture recording, and the property panel: each derived its target
from selectorFromSelection, which hands back a bare class for an id-less
element, so one edit authored a tween over all five siblings and the
timeline collapsed their rows into one.

Route every path that authors a NEW tween through the existing ladder:

- ensureElementAddressable now accepts selection.selector only when it
  addresses exactly one element, so the id-minting fallback right below it
  (previously unreachable whenever any selector was present) does the work.
- gsapDragCommit's five new-tween branches go through one newTweenTarget
  helper; instant patches reuse the written target so the runtime moves the
  element the source write names.
- useGestureCommit and useAnimatedPropertyCommit keep the existing selector
  for matching/retargeting and author new tweens with a separate write
  selector.

Retargets of an EXISTING tween are deliberately untouched: they keep
anim.targetSelector, so a tween aimed at a whole group stays aimed at it.

Narrowing the write alone regressed idempotency, verified by test: the
"is there already a write for this element" lookups matched targetSelector
by string, so the next nudge missed the write it had just made and appended
a second, conflicting one. The read half now falls back to the live DOM
(tweenTargetsElement, same contract as getAnimationsForElement), which also
still matches a deliberate group tween.

Tests reproduce each site through a real writer, re-parse with the real
parser, and resolve through resolveSelectorElementIds (what feeds the
keyframe cache and the lanes), plus pins for the new-tween vs
retarget-existing distinction so a future change cannot collapse the two.

packages/studio/src/hooks/gsapDragCommit.ts

@@ -12,7 +12,7 @@ import { usePlayerStore } from "../player/store/playerStore";
 import { readRuntimeKeyframes, scanAllRuntimeKeyframes } from "./gsapRuntimeKeyframes";
 import { resolveTweenStart, resolveTweenDuration } from "../utils/globalTimeCompiler";
 import { roundTo3 } from "../utils/rounding";
-import { computeElementPercentage, idSelector } from "./gsapShared";
+import { computeElementPercentage, idSelector, writeTargetSelector } from "./gsapShared";
 import { computeDraggedGsapPosition } from "./draggedGsapPosition";
 import type { RuntimeTweenChange } from "./gsapRuntimePatch";
 import { isGestureTransactionCommit, runGestureTransaction } from "./gestureTransaction";
@@ -44,6 +44,18 @@ export interface GsapDragCommitCallbacks {
   fetchAnimations?: () => Promise<GsapAnimation[]>;
 }
 
+/**
+ * The target for a tween these helpers are about to CREATE. Callers derive
+ * `selector` with `selectorFromSelection`, which hands back a bare class for an
+ * id-less element: authoring that widens a one-element drag/resize/rotate into a
+ * write over every sibling sharing the class. Retargets of an EXISTING tween
+ * must NOT come through here (they keep `anim.targetSelector`, so a tween the
+ * author aimed at a group stays aimed at it).
+ */
+function newTweenTarget(selection: DomEditSelection, selector: string): string {
+  return writeTargetSelector(selection) ?? selector;
+}
+
 // Re-export for backward compatibility with existing imports.
 export function computeCurrentPercentage(
   selection: DomEditSelection,
@@ -75,7 +87,7 @@ async function replaceKeyframedPositionHold(
       selection,
       {
         type: "add",
-        targetSelector: selector,
+        targetSelector: newTweenTarget(selection, selector),
         method: "set",
         position: 0,
         properties,
@@ -199,11 +211,14 @@ export async function commitStaticGsapPosition(
   }
   // New static hold → a base `gsap.set` (off-timeline, no 0% keyframe marker), with
   // an instant patch so the first nudge shows immediately (no soft-reload flash).
+  // The patch reuses the WRITTEN target so the runtime moves exactly the element
+  // the source write names.
+  const target = newTweenTarget(selection, selector);
   await callbacks.commitMutation(
     selection,
     {
       type: "add",
-      targetSelector: selector,
+      targetSelector: target,
       method: "set",
       position: 0,
       properties: { x: newX, y: newY },
@@ -212,7 +227,10 @@ export async function commitStaticGsapPosition(
     {
       label: "Move layer",
       softReload: true,
-      instantPatch: { selector, change: { kind: "global-set", props: { x: newX, y: newY } } },
+      instantPatch: {
+        selector: target,
+        change: { kind: "global-set", props: { x: newX, y: newY } },
+      },
     },
   );
 }
@@ -252,11 +270,12 @@ export async function commitStaticGsapRotation(
     return;
   }
   // New static hold → off-timeline `gsap.set` (no 0% keyframe marker) + instant patch.
+  const target = newTweenTarget(selection, selector);
   await callbacks.commitMutation(
     selection,
     {
       type: "add",
-      targetSelector: selector,
+      targetSelector: target,
       method: "set",
       position: 0,
       properties: { rotation: newRotation },
@@ -265,7 +284,10 @@ export async function commitStaticGsapRotation(
     {
       label: "Rotate layer",
       softReload: true,
-      instantPatch: { selector, change: { kind: "global-set", props: { rotation: newRotation } } },
+      instantPatch: {
+        selector: target,
+        change: { kind: "global-set", props: { rotation: newRotation } },
+      },
     },
   );
 }
@@ -305,7 +327,7 @@ export async function commitStaticGsapSize(
     selection,
     {
       type: "add",
-      targetSelector: selector,
+      targetSelector: newTweenTarget(selection, selector),
       method: "set",
       position: 0,
       properties: { width, height },
@@ -393,7 +415,7 @@ export async function commitKeyframedSizeFromResize(
     selection,
     {
       type: "add-with-keyframes",
-      targetSelector: selector,
+      targetSelector: newTweenTarget(selection, selector),
       position: roundTo3(ts),
       duration: roundTo3(td),
       keyframes,

packages/studio/src/hooks/gsapDragStaticSetHelpers.ts

@@ -1,6 +1,6 @@
 import type { GsapAnimation } from "@hyperframes/core/gsap-parser";
 import type { RuntimeTweenChange, SetPatchProps } from "./gsapRuntimePatch";
-import { isInstantHold } from "./gsapShared";
+import { isInstantHold, tweenTargetsElement } from "./gsapShared";
 
 /** The shape of an `update-property` mutation a static-set nudge POSTs. */
 interface UpdatePropertyMutation {
@@ -34,12 +34,13 @@ export function setPatchFromUpdateProperty(
 function findPositionSetAnimation(
   animations: GsapAnimation[],
   selector: string,
+  element?: Element | null,
 ): GsapAnimation | null {
   return (
     animations.find(
       (a) =>
         a.method === "set" &&
-        a.targetSelector === selector &&
+        tweenTargetsElement(a.targetSelector, selector, element) &&
         ("x" in a.properties || "y" in a.properties),
     ) ?? null
   );
@@ -61,12 +62,16 @@ function findPositionSetAnimation(
 export function findExistingPositionWrite(
   animations: GsapAnimation[],
   selector: string,
+  element?: Element | null,
 ): GsapAnimation | null {
-  const set = findPositionSetAnimation(animations, selector);
+  const set = findPositionSetAnimation(animations, selector, element);
   if (set) return set;
   return (
     animations.find(
-      (a) => a.targetSelector === selector && a.propertyGroup === "position" && isInstantHold(a),
+      (a) =>
+        tweenTargetsElement(a.targetSelector, selector, element) &&
+        a.propertyGroup === "position" &&
+        isInstantHold(a),
     ) ?? null
   );
 }
@@ -74,10 +79,14 @@ export function findExistingPositionWrite(
 export function findRotationSetAnimation(
   animations: GsapAnimation[],
   selector: string,
+  element?: Element | null,
 ): GsapAnimation | null {
   return (
     animations.find(
-      (a) => isInstantHold(a) && a.targetSelector === selector && "rotation" in a.properties,
+      (a) =>
+        isInstantHold(a) &&
+        tweenTargetsElement(a.targetSelector, selector, element) &&
+        "rotation" in a.properties,
     ) ?? null
   );
 }
@@ -85,12 +94,13 @@ export function findRotationSetAnimation(
 export function findSizeSetAnimation(
   animations: GsapAnimation[],
   selector: string,
+  element?: Element | null,
 ): GsapAnimation | null {
   return (
     animations.find(
       (a) =>
         isInstantHold(a) &&
-        a.targetSelector === selector &&
+        tweenTargetsElement(a.targetSelector, selector, element) &&
         ("width" in a.properties || "height" in a.properties),
     ) ?? null
   );

packages/studio/src/hooks/gsapResizeIntercept.ts

@@ -79,7 +79,7 @@ export async function tryGsapResizeIntercept(
   if (!anim || isInstantHold(anim)) {
     const sel = selectorFromSelection(selection);
     if (!sel) return false;
-    const sizeSet = anim ?? findSizeSetAnimation(animations, sel);
+    const sizeSet = anim ?? findSizeSetAnimation(animations, sel, selection.element);
 
     // If the element is animated (has a real tween, not just a static size
     // hold), keyframe the size at the playhead so other keyframes keep theirs —
@@ -242,7 +242,7 @@ export async function tryGsapResizeIntercept(
     const currentAnimations = fetchFallbackAnimations
       ? await fetchFallbackAnimations()
       : (resolved?.animations ?? animations);
-    const existingSet = findExistingPositionWrite(currentAnimations, selector);
+    const existingSet = findExistingPositionWrite(currentAnimations, selector, selection.element);
     // Delta chosen so the drag-path math composes back to exactly `corrected`
     // (no drag scratch attrs exist during a resize, so base = gsapPos).
     await commitStaticGsapPosition(

packages/studio/src/hooks/gsapRuntimeBridge.ts

@@ -213,7 +213,7 @@ export async function tryGsapDragIntercept(
     const existingSet =
       posAnim && isInstantHold(posAnim) && posAnim.targetSelector === selector
         ? posAnim
-        : findExistingPositionWrite(resolvedAnimations, selector);
+        : findExistingPositionWrite(resolvedAnimations, selector, selection.element);
     await commitStaticGsapPosition(selection, offset, gsapPos, selector, existingSet, {
       commitMutation,
       fetchAnimations: fetchFallbackAnimations,
@@ -301,7 +301,8 @@ export async function tryGsapRotationIntercept(
   // rotation set in place, else add a new one. This replaces the old
   // `--hf-studio-rotation` CSS-var fallback (the same dual-channel bug class).
   if (!anim || isInstantHold(anim)) {
-    const existingSet = anim ?? findRotationSetAnimation(resolvedAnimations, selector);
+    const existingSet =
+      anim ?? findRotationSetAnimation(resolvedAnimations, selector, selection.element);
     await commitStaticGsapRotation(selection, newRotation, selector, existingSet, {
       commitMutation,
       fetchAnimations: fetchFallbackAnimations,

packages/studio/src/hooks/gsapScriptCommitHelpers.ts

@@ -2,17 +2,32 @@ import { findUnsafeDomPatchValues } from "@hyperframes/core/studio-api/finite-mu
 import type { DomEditSelection } from "../components/editor/domEditingTypes";
 
 export { PROPERTY_DEFAULTS } from "./gsapShared";
-import { idSelector } from "./gsapShared";
+import { idSelector, matchesExactlyOne } from "./gsapShared";
 
+/**
+ * The selector to author a NEW tween against, minting an id on the element when
+ * it has no address of its own.
+ *
+ * `selection.selector` is only usable when it addresses ONE element:
+ * `buildStableSelector` hands back a bare class for an id-less element, so
+ * returning it unconditionally aimed "add animation" at every sibling sharing
+ * the class (the attribution blow-up that collapsed the timeline to one row,
+ * see writeTargetSelector). A non-unique selector falls through to the id mint
+ * below, which is the stronger fix here than a structural path: the id it writes
+ * back to the source also makes every later lookup for this element exact.
+ */
 export function ensureElementAddressable(selection: DomEditSelection): {
   selector: string;
   autoId?: string;
 } {
   if (selection.id) return { selector: idSelector(selection.id) };
-  if (selection.selector) return { selector: selection.selector };
 
   const el = selection.element;
   const doc = el.ownerDocument;
+  if (selection.selector && matchesExactlyOne(doc, selection.selector, el)) {
+    return { selector: selection.selector };
+  }
+
   const tag = el.tagName.toLowerCase();
   let id = tag;
   let n = 1;

packages/studio/src/hooks/gsapShared.ts

@@ -186,7 +186,12 @@ function attributeSelector(name: string, value: string): string {
   return `[${name}="${value.replace(/(["\\])/g, "\\$1")}"]`;
 }
 
-function matchesExactlyOne(doc: Document, selector: string, element: Element): boolean {
+/**
+ * Whether `selector` addresses `element` AND NOTHING ELSE. The single test for
+ * "this string is safe to author a new tween against": a selector that also
+ * hits siblings writes a tween that animates all of them.
+ */
+export function matchesExactlyOne(doc: Document, selector: string, element: Element): boolean {
   try {
     const matches = doc.querySelectorAll(selector);
     return matches.length === 1 && matches[0] === element;
@@ -286,6 +291,31 @@ export function existingTweenTargetSelector(
   return selectorFromSelection(selection);
 }
 
+/**
+ * The read half of {@link writeTargetSelector}: does an already-authored tween
+ * write THIS element?
+ *
+ * String equality against `selectorFromSelection` alone is not enough once new
+ * tweens are authored with a narrowed one-element selector: the next edit would
+ * miss the write it just made and append a second, conflicting one. Falling back
+ * to the live DOM keeps the pair consistent, and still matches a deliberate group
+ * tween (`.group` matches each of its siblings) so merges into it keep working.
+ */
+export function tweenTargetsElement(
+  targetSelector: string,
+  selector: string,
+  element: Element | null | undefined,
+): boolean {
+  if (targetSelector === selector) return true;
+  if (!element) return false;
+  try {
+    return element.matches(targetSelector);
+  } catch {
+    // Not a selector `matches()` understands, so it never addressed this element.
+    return false;
+  }
+}
+
 // ── Percentage computation ────────────────────────────────────────────────────
 
 /**

packages/studio/src/hooks/newTweenTarget.test.ts

@@ -0,0 +1,364 @@
+// @vitest-environment jsdom
+/**
+ * Sibling writers of the "add keyframe at playhead" path fixed in
+ * gsapShared.writeTarget.test.ts. Every mutation that authors a NEW tween must
+ * address ONE element; a bare class attributes the write to every sibling that
+ * shares it, which is what collapsed the timeline to a single row.
+ *
+ * Same round trip as the U3 test: author through the real writer, re-parse with
+ * the real parser, resolve through the very function that feeds the keyframe
+ * cache and the lanes.
+ */
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { parseGsapScript } from "@hyperframes/core/gsap-parser";
+import type { GsapAnimation } from "@hyperframes/core/gsap-parser";
+import type { DomEditSelection } from "../components/editor/domEditingTypes";
+import { buildStableSelector, getSelectorIndex } from "../components/editor/domEditingDom";
+import { resolveSelectorElementIds } from "./gsapShared";
+import { ensureElementAddressable } from "./gsapScriptCommitHelpers";
+import {
+  commitStaticGsapPosition,
+  commitStaticGsapRotation,
+  commitStaticGsapSize,
+  commitKeyframedSizeFromResize,
+  commitWholePathOffset,
+  findExistingPositionWrite,
+} from "./gsapDragCommit";
+import { promoteSetToKeyframes } from "./useEnableKeyframes";
+
+afterEach(() => {
+  document.body.innerHTML = "";
+});
+
+function selectionFor(el: HTMLElement): DomEditSelection {
+  const selector = buildStableSelector(el);
+  return {
+    element: el,
+    id: el.id || undefined,
+    hfId: el.getAttribute("data-hf-id") || undefined,
+    selector,
+    selectorIndex: getSelectorIndex(document, el, selector, "index.html", null),
+    sourceFile: "index.html",
+    dataAttributes: { start: "0", duration: "2" },
+  } as unknown as DomEditSelection;
+}
+
+/** Five class-only siblings, each with an id so attribution is nameable. */
+function mountGroupSiblings(): HTMLElement[] {
+  document.body.innerHTML = `
+    <div id="scene" class="clip" data-start="0" data-duration="2">
+      <div class="group" id="group-0"></div>
+      <div class="group" id="group-1"></div>
+      <div class="group" id="group-2"></div>
+      <div class="group" id="group-3"></div>
+      <div class="group" id="group-4"></div>
+    </div>
+  `;
+  return Array.from(document.querySelectorAll<HTMLElement>(".group"));
+}
+
+/**
+ * The selection production hands these writers: the element HAS an id in the
+ * DOM (so resolveSelectorElementIds can name it) but the SELECTION carries none,
+ * which is the id-less shape buildStableSelector answers with a bare class.
+ */
+function classOnlySelection(el: HTMLElement): DomEditSelection {
+  return { ...selectionFor(el), id: undefined, selector: ".group" } as DomEditSelection;
+}
+
+/** The elements a written targetSelector actually attributes the tween to. */
+function attributedTo(targetSelector: string): string[] {
+  return resolveSelectorElementIds(targetSelector, document);
+}
+
+function recorder() {
+  const mutations: Array<Record<string, unknown>> = [];
+  const commitMutation = vi.fn(async (_sel, mutation, _opts) => {
+    mutations.push(mutation as Record<string, unknown>);
+  });
+  return { mutations, callbacks: { commitMutation } as never };
+}
+
+/** Every `targetSelector` a run of mutations wrote. */
+function writtenTargets(mutations: Array<Record<string, unknown>>): string[] {
+  return mutations.map((m) => m.targetSelector).filter((s): s is string => typeof s === "string");
+}
+
+describe("ensureElementAddressable — add-animation button", () => {
+  it("addresses one element when the selection's only identity is a shared class", () => {
+    // Truly id-less siblings: the shape production reaches this path with (an
+    // element WITH an id never gets here, selection.id short-circuits above).
+    document.body.innerHTML = `
+      <div id="scene" class="clip">
+        <div class="group"></div><div class="group"></div><div class="group"></div>
+      </div>
+    `;
+    const el = document.querySelectorAll<HTMLElement>(".group")[1]!;
+    const selection = selectionFor(el);
+    expect(selection.selector).toBe(".group");
+
+    const { selector, autoId } = ensureElementAddressable(selection);
+
+    expect(autoId).toBeTruthy();
+    expect(document.querySelectorAll(selector)).toHaveLength(1);
+    expect(document.querySelector(selector)).toBe(el);
+    expect(attributedTo(selector)).toEqual([autoId]);
+  });
+
+  it("keeps a unique #id target", () => {
+    document.body.innerHTML = `<div id="box" class="card"></div>`;
+    const el = document.querySelector<HTMLElement>("#box")!;
+
+    expect(ensureElementAddressable(selectionFor(el)).selector).toBe("#box");
+  });
+
+  it("keeps an already-unique class selector as authored", () => {
+    document.body.innerHTML = `<div id="scene"><div class="header"></div></div>`;
+    const el = document.querySelector<HTMLElement>(".header")!;
+
+    expect(ensureElementAddressable(selectionFor(el)).selector).toBe(".header");
+  });
+
+  it("still mints an id when there is no live element to disambiguate against", () => {
+    document.body.innerHTML = `<div id="scene"><div></div></div>`;
+    const el = document.querySelector<HTMLElement>("#scene > div")!;
+    const selection = { ...selectionFor(el), selector: undefined } as DomEditSelection;
+
+    const { selector, autoId } = ensureElementAddressable(selection);
+
+    expect(autoId).toBe("div");
+    expect(selector).toBe("#div");
+  });
+});
+
+describe("gsapDragCommit — new-tween targets", () => {
+  it("commitStaticGsapPosition authors the new set against one element", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+
+    await commitStaticGsapPosition(
+      classOnlySelection(groups[2]!),
+      { x: 10, y: 10 },
+      { x: 0, y: 0 },
+      ".group",
+      null,
+      callbacks,
+    );
+
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toEqual(["group-2"]);
+  });
+
+  it("commitStaticGsapRotation authors the new set against one element", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+
+    await commitStaticGsapRotation(classOnlySelection(groups[1]!), 42, ".group", null, callbacks);
+
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toEqual(["group-1"]);
+  });
+
+  it("commitStaticGsapSize authors the new set against one element", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+
+    await commitStaticGsapSize(
+      classOnlySelection(groups[4]!),
+      { width: 100, height: 50 },
+      ".group",
+      null,
+      callbacks,
+    );
+
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toEqual(["group-4"]);
+  });
+
+  it("commitKeyframedSizeFromResize authors the new keyframe tween against one element", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+    const animatedTween = {
+      id: "t1",
+      targetSelector: ".group",
+      method: "to",
+      properties: {},
+      resolvedStart: 0,
+      duration: 2,
+      keyframes: { keyframes: [{ percentage: 0, properties: { x: 0 } }] },
+    } as unknown as GsapAnimation;
+
+    const handled = await commitKeyframedSizeFromResize(
+      classOnlySelection(groups[3]!),
+      { width: 80, height: 40 },
+      ".group",
+      null,
+      animatedTween,
+      callbacks,
+    );
+
+    expect(handled).toBe(true);
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toEqual(["group-3"]);
+  });
+
+  it("commitStaticGsapPosition replaces a corrupt keyframed hold against one element", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+    const corruptHold = {
+      id: "hold-1",
+      targetSelector: ".group",
+      method: "to",
+      properties: {},
+      duration: 0,
+      keyframes: { keyframes: [{ percentage: 0, properties: { x: 0, y: 0 } }] },
+    } as unknown as GsapAnimation;
+
+    await commitStaticGsapPosition(
+      classOnlySelection(groups[0]!),
+      { x: 5, y: 5 },
+      { x: 0, y: 0 },
+      ".group",
+      corruptHold,
+      callbacks,
+    );
+
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toEqual(["group-0"]);
+  });
+});
+
+describe("gsapDragCommit — retargeting an existing tween is left alone", () => {
+  it("commitWholePathOffset keeps the tween's own group target", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+    const groupTween = {
+      id: "t-group",
+      targetSelector: ".group",
+      method: "to",
+      properties: { x: 100 },
+      resolvedStart: 0,
+      duration: 2,
+    } as unknown as GsapAnimation;
+
+    await commitWholePathOffset(
+      classOnlySelection(groups[2]!),
+      groupTween,
+      { x: 10, y: 0 },
+      { x: 0, y: 0 },
+      null,
+      ".group",
+      callbacks,
+    );
+
+    // A tween the author aimed at all five siblings must STAY aimed at all five:
+    // narrowing it here would silently drop four elements out of the animation.
+    expect(writtenTargets(mutations)[0]).toBe(".group");
+    expect(attributedTo(writtenTargets(mutations)[0]!)).toHaveLength(5);
+  });
+});
+
+/**
+ * The write selector and the "is there already a write for this element?"
+ * lookup are two halves of one contract. Narrowing only the write half would
+ * make the next nudge miss its own previous write and append a second one — the
+ * duplicate-position-write bug findExistingPositionWrite exists to prevent.
+ */
+describe("a re-nudge updates its own previous write instead of stacking a second one", () => {
+  it("finds the write the first nudge authored", async () => {
+    const groups = mountGroupSiblings();
+    const selection = classOnlySelection(groups[2]!);
+    const first = recorder();
+
+    await commitStaticGsapPosition(
+      selection,
+      { x: 10, y: 10 },
+      { x: 0, y: 0 },
+      ".group",
+      null,
+      first.callbacks,
+    );
+    const written = writtenTargets(first.mutations)[0]!;
+
+    // Read the first write back the way the next drag does: parse the source,
+    // then run the production lookup for this element's position write.
+    const script = `
+const tl = gsap.timeline({ paused: true });
+gsap.set(${JSON.stringify(written)}, { x: 10, y: 10 });
+`.trim();
+    const animations = parseGsapScript(script).animations;
+    const existing = findExistingPositionWrite(animations, ".group", selection.element);
+    expect(existing).toBeTruthy();
+
+    const second = recorder();
+    await commitStaticGsapPosition(
+      selection,
+      { x: 5, y: 0 },
+      { x: 10, y: 10 },
+      ".group",
+      existing,
+      second.callbacks,
+    );
+
+    expect(second.mutations[0]!.type).toBe("update-properties");
+    expect(second.mutations[0]!.animationId).toBe(existing!.id);
+  });
+});
+
+/**
+ * Candidate C. Every `replace-with-keyframes` in useEnableKeyframes names an
+ * `animationId` parsed out of the CURRENT SOURCE (the anims list comes from
+ * tryFetchAnimationsForElement), so each one rewrites a tween the author already
+ * has. Narrowing those to one element would silently drop the other four
+ * siblings out of an animation that was aimed at the group on purpose.
+ */
+describe("useEnableKeyframes — rewriting an existing tween keeps its group target", () => {
+  it("promoteSetToKeyframes leaves a group-authored set aimed at the group", async () => {
+    const groups = mountGroupSiblings();
+    const mutations: Array<Record<string, unknown>> = [];
+    const setAnim = {
+      id: "set-group",
+      targetSelector: ".group",
+      method: "set",
+      properties: { x: 0, y: 0 },
+      resolvedStart: 0,
+      duration: 0,
+    } as unknown as GsapAnimation;
+    const session = {
+      commitMutation: async (mutation: Record<string, unknown>) => {
+        mutations.push(mutation);
+      },
+      handleGsapRemoveKeyframe: vi.fn(),
+    };
+
+    // Playhead at the set: the branch that replaces it with a single keyframe,
+    // which can source its value from the set itself (no live iframe needed).
+    await promoteSetToKeyframes(session as never, classOnlySelection(groups[2]!), setAnim, 0, null);
+
+    expect(mutations[0]!.type).toBe("replace-with-keyframes");
+    expect(mutations[0]!.animationId).toBe("set-group");
+    expect(mutations[0]!.targetSelector).toBe(".group");
+    expect(attributedTo(mutations[0]!.targetSelector as string)).toHaveLength(5);
+  });
+});
+
+describe("the written selector survives the real writer and parser", () => {
+  it("re-parses to a tween attributed to the one element it targeted", async () => {
+    const groups = mountGroupSiblings();
+    const { mutations, callbacks } = recorder();
+
+    await commitStaticGsapPosition(
+      classOnlySelection(groups[2]!),
+      { x: 10, y: 10 },
+      { x: 0, y: 0 },
+      ".group",
+      null,
+      callbacks,
+    );
+    const written = writtenTargets(mutations)[0]!;
+
+    const script = `
+const tl = gsap.timeline({ paused: true });
+gsap.set(${JSON.stringify(written)}, { x: 10, y: 10 });
+`.trim();
+    const parsed = parseGsapScript(script).animations.find((a) => a.targetSelector === written);
+
+    expect(parsed).toBeTruthy();
+    expect(resolveSelectorElementIds(parsed!.targetSelector, document)).toEqual(["group-2"]);
+  });
+});

packages/studio/src/hooks/newTweenTargetHooks.test.tsx

@@ -0,0 +1,255 @@
+// @vitest-environment jsdom
+/**
+ * Hook-level siblings of newTweenTarget.test.ts: the property panel and the
+ * gesture recorder also author NEW tweens, so they face the same bare-class
+ * blow-up. Driven through the real hooks so the classification under test
+ * (new tween vs retarget of an existing one) is the production one.
+ */
+import React, { act } from "react";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import type { GsapAnimation } from "@hyperframes/core/gsap-parser";
+import type { DomEditSelection } from "../components/editor/domEditingTypes";
+import { usePlayerStore } from "../player/store/playerStore";
+import { resolveSelectorElementIds } from "./gsapShared";
+import { useAnimatedPropertyCommit } from "./useAnimatedPropertyCommit";
+import { useGestureCommit } from "./useGestureCommit";
+import { mountReactHarness, installReactActEnvironment } from "./domSelectionTestHarness";
+
+installReactActEnvironment();
+
+const frozenSamples = [
+  { time: 0, properties: { x: 0, y: 0 } },
+  { time: 0.5, properties: { x: 60, y: 10 } },
+  { time: 1, properties: { x: 120, y: 40 } },
+];
+
+vi.mock("./useGestureRecording", () => ({
+  useGestureRecording: () => ({
+    startRecording: vi.fn(),
+    stopRecording: () => frozenSamples,
+    clearSamples: vi.fn(),
+    samples: frozenSamples,
+  }),
+}));
+
+afterEach(() => {
+  document.body.innerHTML = "";
+  usePlayerStore.setState({ autoKeyframeEnabled: true, currentTime: 0 });
+});
+
+function mountGroupSiblings(): HTMLElement[] {
+  document.body.innerHTML = `
+    <div id="scene" class="clip" data-start="0" data-duration="2">
+      <div class="group" id="group-0"></div>
+      <div class="group" id="group-1"></div>
+      <div class="group" id="group-2"></div>
+      <div class="group" id="group-3"></div>
+      <div class="group" id="group-4"></div>
+    </div>
+  `;
+  return Array.from(document.querySelectorAll<HTMLElement>(".group"));
+}
+
+/** The id-less shape buildStableSelector answers with a bare class. */
+function classOnlySelection(el: HTMLElement): DomEditSelection {
+  return {
+    element: el,
+    id: undefined,
+    selector: ".group",
+    selectorIndex: Array.prototype.indexOf.call(el.parentElement!.children, el),
+    sourceFile: "index.html",
+    dataAttributes: { start: "0", duration: "2" },
+  } as unknown as DomEditSelection;
+}
+
+function attributedTo(targetSelector: unknown): string[] {
+  return resolveSelectorElementIds(String(targetSelector), document);
+}
+
+type Commit = (
+  selection: DomEditSelection,
+  props: Record<string, number | string>,
+) => Promise<void>;
+
+function renderPropertyCommit(
+  animations: GsapAnimation[],
+  mutations: Array<Record<string, unknown>>,
+  onReady: (commit: Commit) => void,
+) {
+  function Harness() {
+    const { commitAnimatedProperties } = useAnimatedPropertyCommit({
+      selectedGsapAnimations: animations,
+      gsapCommitMutation: async (_sel: DomEditSelection, mutation: Record<string, unknown>) => {
+        mutations.push(mutation);
+      },
+      addGsapAnimation: vi.fn(),
+      convertToKeyframes: vi.fn(),
+      previewIframeRef: { current: null },
+      bumpGsapCache: vi.fn(),
+    } as never);
+    onReady(commitAnimatedProperties);
+    return null;
+  }
+  return mountReactHarness(<Harness />);
+}
+
+describe("useAnimatedPropertyCommit — new-tween targets", () => {
+  it("authors a new static set against one element", async () => {
+    const groups = mountGroupSiblings();
+    const mutations: Array<Record<string, unknown>> = [];
+    let commit: Commit | undefined;
+    const root = renderPropertyCommit([], mutations, (fn) => (commit = fn));
+
+    await act(async () => {
+      await commit!(classOnlySelection(groups[2]!), { rotationX: 30 });
+    });
+
+    const added = mutations.find((m) => m.type === "add");
+    expect(added).toBeTruthy();
+    expect(attributedTo(added!.targetSelector)).toEqual(["group-2"]);
+    act(() => root.unmount());
+  });
+
+  it("authors the first same-group keyframe tween against one element", async () => {
+    const groups = mountGroupSiblings();
+    // A position tween exists, so the element IS animated; a rotation edit has
+    // no same-group tween to join and must author a fresh one.
+    const positionTween = {
+      id: "t-pos",
+      targetSelector: ".group",
+      propertyGroup: "position",
+      method: "to",
+      properties: { x: 0 },
+      resolvedStart: 0,
+      duration: 2,
+      keyframes: {
+        keyframes: [
+          { percentage: 0, properties: { x: 0 } },
+          { percentage: 100, properties: { x: 50 } },
+        ],
+      },
+    } as unknown as GsapAnimation;
+    const mutations: Array<Record<string, unknown>> = [];
+    let commit: Commit | undefined;
+    const root = renderPropertyCommit([positionTween], mutations, (fn) => (commit = fn));
+
+    await act(async () => {
+      await commit!(classOnlySelection(groups[1]!), { rotationY: 15 });
+    });
+
+    const added = mutations.find((m) => m.type === "add-with-keyframes");
+    expect(added).toBeTruthy();
+    expect(attributedTo(added!.targetSelector)).toEqual(["group-1"]);
+    act(() => root.unmount());
+  });
+
+  it("leaves an existing group tween aimed at its whole group", async () => {
+    const groups = mountGroupSiblings();
+    usePlayerStore.setState({ autoKeyframeEnabled: false, currentTime: 0 });
+    const groupTween = {
+      id: "t-pos",
+      targetSelector: ".group",
+      propertyGroup: "position",
+      method: "to",
+      properties: { x: 0 },
+      resolvedStart: 0,
+      duration: 2,
+      keyframes: {
+        keyframes: [
+          { percentage: 0, properties: { x: 0, y: 0 } },
+          { percentage: 100, properties: { x: 50, y: 0 } },
+        ],
+      },
+    } as unknown as GsapAnimation;
+    const mutations: Array<Record<string, unknown>> = [];
+    let commit: Commit | undefined;
+    const root = renderPropertyCommit([groupTween], mutations, (fn) => (commit = fn));
+
+    await act(async () => {
+      await commit!(classOnlySelection(groups[2]!), { x: 90 });
+    });
+
+    const replaced = mutations.find((m) => m.type === "replace-with-keyframes");
+    expect(replaced).toBeTruthy();
+    expect(replaced!.targetSelector).toBe(".group");
+    act(() => root.unmount());
+  });
+});
+
+function renderGestureCommit(
+  animations: GsapAnimation[],
+  mutations: Array<Record<string, unknown>>,
+  selection: DomEditSelection,
+) {
+  let toggle: (() => void) | undefined;
+  function Harness() {
+    const { handleToggleRecording } = useGestureCommit({
+      domEditSessionRef: {
+        current: {
+          domEditSelection: selection,
+          selectedGsapAnimations: animations,
+          commitMutation: async (mutation: Record<string, unknown>) => {
+            mutations.push(mutation);
+          },
+        },
+      } as never,
+      previewIframeRef: { current: document.createElement("iframe") },
+      showToast: vi.fn(),
+      isGestureRecordingRef: { current: false },
+    });
+    toggle = handleToggleRecording;
+    return null;
+  }
+  const root = mountReactHarness(<Harness />);
+  return { root, toggle: () => toggle!() };
+}
+
+describe("useGestureCommit — new-tween targets", () => {
+  it("authors the recorded tween against one element", async () => {
+    const groups = mountGroupSiblings();
+    const mutations: Array<Record<string, unknown>> = [];
+    const { root, toggle } = renderGestureCommit([], mutations, classOnlySelection(groups[3]!));
+
+    act(() => toggle()); // start
+    await act(async () => {
+      toggle(); // stop + commit
+      await Promise.resolve();
+    });
+
+    const added = mutations.find((m) => m.type === "add-with-keyframes");
+    expect(added).toBeTruthy();
+    expect(attributedTo(added!.targetSelector)).toEqual(["group-3"]);
+    act(() => root.unmount());
+  });
+
+  it("leaves a merged existing group tween aimed at its whole group", async () => {
+    const groups = mountGroupSiblings();
+    const existing = {
+      id: "t-pos",
+      targetSelector: ".group",
+      propertyGroup: "position",
+      method: "to",
+      properties: { x: 0 },
+      resolvedStart: 0,
+      duration: 2,
+      keyframes: { keyframes: [{ percentage: 0, properties: { x: 0, y: 0 } }] },
+    } as unknown as GsapAnimation;
+    const mutations: Array<Record<string, unknown>> = [];
+    const { root, toggle } = renderGestureCommit(
+      [existing],
+      mutations,
+      classOnlySelection(groups[3]!),
+    );
+
+    act(() => toggle());
+    await act(async () => {
+      toggle();
+      await Promise.resolve();
+    });
+
+    const replaced = mutations.find((m) => m.type === "replace-with-keyframes");
+    expect(replaced).toBeTruthy();
+    expect(replaced!.targetSelector).toBe(".group");
+    act(() => root.unmount());
+  });
+});

packages/studio/src/hooks/useAnimatedPropertyCommit.ts

@@ -14,7 +14,13 @@ import type { DomEditSelection } from "../components/editor/domEditingTypes";
 import { usePlayerStore } from "../player/store/playerStore";
 import { readAllAnimatedProperties, readGsapProperty } from "./gsapRuntimeBridge";
 import type { SetPatchProps } from "./gsapRuntimePatch";
-import { selectorFromSelection, computeElementPercentage, isInstantHold } from "./gsapShared";
+import {
+  selectorFromSelection,
+  computeElementPercentage,
+  isInstantHold,
+  writeTargetSelector,
+  tweenTargetsElement,
+} from "./gsapShared";
 import { resolveTweenStart, resolveTweenDuration } from "../utils/globalTimeCompiler";
 import { roundTo3 } from "../utils/rounding";
 import { commitWholePropertyOffset } from "./gsapWholePropertyOffsetCommit";
@@ -185,7 +191,9 @@ async function commitStaticSet(
     batch.push(entry);
     byGroup.set(group, batch);
   }
-  const staticWrites = animations.filter((a) => isInstantHold(a) && a.targetSelector === selector);
+  const staticWrites = animations.filter(
+    (a) => isInstantHold(a) && tweenTargetsElement(a.targetSelector, selector, selection.element),
+  );
   // Resolve every group's target BEFORE committing anything, and coalesce
   // groups that land on the SAME write into one commit: the snapshot is captured
   // once, so if two groups resolved to one legacy mixed write, a first
@@ -243,11 +251,14 @@ async function addGlobalStaticSet(
   for (const [k, v] of batch) {
     if (typeof v === "number") numericProps[k as keyof SetPatchProps] = v;
   }
+  // A brand-new write, so it must address ONE element: `selector` is the bare
+  // class an id-less selection yields, which would hold every sibling.
+  const target = writeTargetSelector(selection) ?? selector;
   await commit(
     selection,
     {
       type: "add",
-      targetSelector: selector,
+      targetSelector: target,
       method: "set",
       position: 0,
       properties: Object.fromEntries(batch),
@@ -259,7 +270,7 @@ async function addGlobalStaticSet(
       ...(Object.keys(numericProps).length > 0
         ? {
             instantPatch: {
-              selector,
+              selector: target,
               change: { kind: "global-set" as const, props: numericProps },
             },
           }
@@ -503,7 +514,7 @@ export function useAnimatedPropertyCommit(deps: CommitAnimatedPropertyDeps) {
             selection,
             {
               type: "add-with-keyframes",
-              targetSelector: selector,
+              targetSelector: writeTargetSelector(selection) ?? selector,
               position: roundTo3(tStart),
               duration: roundTo3(tDur),
               keyframes,

packages/studio/src/hooks/useGestureCommit.ts

@@ -13,7 +13,7 @@ import type { GsapAnimation } from "@hyperframes/core/gsap-parser";
 import type { CommitMutationOptions } from "./gsapScriptCommitTypes";
 import { roundTo3 } from "../utils/rounding";
 import { classifyPropertyGroup } from "@hyperframes/core/gsap-parser";
-import { isInstantHold, idSelector } from "./gsapShared";
+import { isInstantHold, idSelector, writeTargetSelector, tweenTargetsElement } from "./gsapShared";
 
 type RecordedKeyframe = {
   percentage: number;
@@ -168,11 +168,17 @@ export function useGestureCommit({
         if (!sortedPcts.includes(0)) sortedPcts.unshift(0);
       }
 
+      // Two different jobs, two different selectors. `selector` is the string an
+      // ALREADY-AUTHORED tween is matched against (and retargeted with, so a
+      // tween aimed at a whole group stays aimed at it). `writeSelector` is what
+      // a NEW tween is authored with: the bare class the id-less case yields here
+      // would record the gesture onto every sibling sharing it.
       const selector = sel.id ? idSelector(sel.id) : sel.selector;
       if (!selector) {
         showToast("Cannot save — element has no selector", "error");
         return;
       }
+      const writeSelector = writeTargetSelector(sel) ?? selector;
       if (liveSession.commitMutation) {
         const recStart = recordingStartTimeRef.current;
         const rawKeyframes = sortedPcts.map((pct) => ({
@@ -186,7 +192,11 @@ export function useGestureCommit({
         );
         const allAnims = liveSession.selectedGsapAnimations ?? [];
         const existingPositionTween = hasPositionProps
-          ? allAnims.find((a) => a.propertyGroup === "position" && a.targetSelector === selector)
+          ? allAnims.find(
+              (a) =>
+                a.propertyGroup === "position" &&
+                tweenTargetsElement(a.targetSelector, selector, sel.element),
+            )
           : undefined;
         if (existingPositionTween) {
           if (isInstantHold(existingPositionTween)) {
@@ -261,7 +271,7 @@ export function useGestureCommit({
                 await liveSession.commitMutation(
                   {
                     type: "add-with-keyframes",
-                    targetSelector: selector,
+                    targetSelector: writeSelector,
                     position: roundTo3(recStart),
                     duration: roundTo3(duration),
                     keyframes: groupKfs,
@@ -287,7 +297,7 @@ export function useGestureCommit({
             await liveSession.commitMutation(
               {
                 type: "add-with-keyframes",
-                targetSelector: selector,
+                targetSelector: writeSelector,
                 position: roundTo3(recStart),
                 duration: roundTo3(duration),
                 keyframes: groupKfs,