fix(parsers): preserve authored keyframe intent

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

@@ -283,6 +283,21 @@ function mockFetchResult(over: Partial<MutationResult> = {}): void {
 }
 
 describe("runCommit — instantPatch wiring", () => {
+  it("explains a deliberate mutation that the server safely rejected as unchanged", async () => {
+    mockFetchResult({ changed: false });
+    const deps = renderCommitHook();
+
+    await act(async () => {
+      await deps.api.commitMutation(
+        selection,
+        { type: "move-keyframe", fromPercentage: 50, toPercentage: 100 },
+        { label: "Move keyframe" },
+      );
+    });
+
+    expect(deps.showToast).toHaveBeenCalledWith("A keyframe already exists at that time", "info");
+  });
+
   it("no-op commit with an instantPatch still patches the runtime (paired x/y commits)", async () => {
     patchRuntimeTweenInPlace.mockReturnValue(true);
     mockFetchResult({ changed: false });

packages/studio/src/hooks/useGsapScriptCommits.ts

@@ -77,6 +77,17 @@ async function mutateGsapScriptBatch(
 
 type ShowToast = (message: string, tone?: "error" | "info") => void;
 
+function showUnchangedMutationFeedback(
+  mutations: Record<string, unknown>[],
+  result: MutationResult,
+  showToast: ShowToast | undefined,
+): void {
+  if (result.changed !== false || mutations.length !== 1) return;
+  if (mutations[0]?.type === "move-keyframe") {
+    showToast?.("A keyframe already exists at that time", "info");
+  }
+}
+
 async function runMutationRequest(
   mutations: Record<string, unknown>[],
   options: CommitMutationOptions,
@@ -94,7 +105,9 @@ async function runMutationRequest(
     );
   }
   try {
-    return await request();
+    const result = await request();
+    showUnchangedMutationFeedback(mutations, result, showToast);
+    return result;
   } catch (error) {
     if (error instanceof GsapMutationHttpError) {
       showToast?.(formatGsapMutationRejectionToast(error), "error");