diff --git a/packages/studio/src/hooks/gsapDragCommit.ts b/packages/studio/src/hooks/gsapDragCommit.ts
index e6f4197987..d2d17c50b3 100644
--- a/packages/studio/src/hooks/gsapDragCommit.ts
+++ b/packages/studio/src/hooks/gsapDragCommit.ts
@@ -135,7 +135,7 @@ export async function materializeIfDynamic(
   void iframe;
   void commitMutation;
   void selection;
-  throw new GsapEditBlockedError("source-uneditable");
+  throw new GsapEditBlockedError("source-uneditable", "geometry-unresolved-source");
 }
 
 // ── Drag → GSAP position math ──────────────────────────────────────────────
diff --git a/packages/studio/src/hooks/gsapEditOutcome.test.ts b/packages/studio/src/hooks/gsapEditOutcome.test.ts
new file mode 100644
index 0000000000..12aa7ff158
--- /dev/null
+++ b/packages/studio/src/hooks/gsapEditOutcome.test.ts
@@ -0,0 +1,115 @@
+import type { GsapAnimation } from "@hyperframes/core/gsap-parser";
+import { describe, expect, it } from "vitest";
+import { buildStudioSaveFailureProperties } from "../utils/studioSaveDiagnostics";
+import {
+  GsapEditBlockedError,
+  assertGsapEditPersisted,
+  directEditOutcomeForProperties,
+} from "./gsapEditOutcome";
+
+function blockDetailFor(error: unknown): unknown {
+  return buildStudioSaveFailureProperties({ source: "gsap_commit", error }).block_detail;
+}
+
+/** Minimal animation that writes `x`, so the editability check actually runs. */
+function animation(overrides: Partial<GsapAnimation> = {}): GsapAnimation {
+  return {
+    id: "a1",
+    targetSelector: "#box",
+    method: "to",
+    position: 0,
+    properties: { x: 100 },
+    ...overrides,
+  } as GsapAnimation;
+}
+
+const POSITION = new Set(["x"]);
+
+describe("a blocked GSAP edit names which of the nine causes it hit", () => {
+  // The three causes inside assertGsapAnimationDirectlyEditable share one
+  // message, so only the detail distinguishes them. Asserted through the
+  // exported wrapper because that is the path a real edit takes — and the
+  // wrapper used to rebuild the outcome from `reason` alone, dropping it.
+  it("reports a runtime-dynamic provenance", () => {
+    const outcome = directEditOutcomeForProperties(
+      [animation({ provenance: { kind: "runtime-dynamic" } })],
+      POSITION,
+    );
+    expect(outcome).toEqual({
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "provenance-runtime-dynamic",
+    });
+  });
+
+  it("reports unresolved keyframes separately from provenance", () => {
+    const outcome = directEditOutcomeForProperties(
+      [animation({ hasUnresolvedKeyframes: true })],
+      POSITION,
+    );
+    expect(outcome).toEqual({
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "unresolved-keyframes",
+    });
+  });
+
+  it("reports an unresolved selector separately from provenance", () => {
+    const outcome = directEditOutcomeForProperties(
+      [animation({ hasUnresolvedSelector: true })],
+      POSITION,
+    );
+    expect(outcome).toEqual({
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "unresolved-selector",
+    });
+  });
+
+  it("still routes a helper or loop to unroll, which has its own message", () => {
+    const outcome = directEditOutcomeForProperties(
+      [animation({ provenance: { kind: "loop" } })],
+      POSITION,
+    );
+    expect(outcome).toEqual({ status: "blocked", reason: "unroll-required", detail: undefined });
+  });
+
+  it("leaves a literal tween editable", () => {
+    expect(directEditOutcomeForProperties([animation()], POSITION)).toEqual({
+      status: "persisted",
+    });
+  });
+
+  it("carries the detail through a returned outcome, not just a thrown one", () => {
+    // gsapRuntimeBridge returns blocked outcomes rather than throwing.
+    expect(() =>
+      assertGsapEditPersisted({
+        status: "blocked",
+        reason: "source-uneditable",
+        detail: "no-position-tween",
+      }),
+    ).toThrow(
+      expect.objectContaining({ name: "GsapEditBlockedError", detail: "no-position-tween" }),
+    );
+  });
+
+  it("surfaces the detail on the telemetry payload", () => {
+    expect(
+      blockDetailFor(
+        new GsapEditBlockedError("source-uneditable", "live-rotation-no-source-tween"),
+      ),
+    ).toBe("live-rotation-no-source-tween");
+  });
+
+  it("omits the detail for a block that has no specific cause", () => {
+    expect(blockDetailFor(new GsapEditBlockedError("no-selector"))).toBeUndefined();
+  });
+
+  it("ignores a detail-shaped field on an error that is not a block", () => {
+    // Guards the name check: any error can carry a `detail`, and reporting a
+    // save failure's detail as a block cause would be a silent mislabel.
+    const impostor = Object.assign(new Error("network down"), { detail: "unresolved-selector" });
+    expect(blockDetailFor(impostor)).toBeUndefined();
+    expect(blockDetailFor("not an error")).toBeUndefined();
+  });
+});
diff --git a/packages/studio/src/hooks/gsapEditOutcome.ts b/packages/studio/src/hooks/gsapEditOutcome.ts
index 9ec2dddd1e..71f4cf0ab7 100644
--- a/packages/studio/src/hooks/gsapEditOutcome.ts
+++ b/packages/studio/src/hooks/gsapEditOutcome.ts
@@ -2,6 +2,27 @@ import { editabilityForProvenance, type GsapAnimation } from "@hyperframes/core/
 
 export type GsapEditBlockReason = "no-selector" | "unroll-required" | "source-uneditable";
 
+/**
+ * Which of the nine situations produced a block. The user-facing `reason` stays
+ * coarse — three messages — but "source-uneditable" alone covers nine distinct
+ * causes, and `edit_blocked` telemetry could not tell them apart. That matters
+ * because the copy ("This animation is computed at runtime") is only literally
+ * true for `provenance-runtime-dynamic`; the others are parser or source-match
+ * limits, where the animation may well be plain authored source.
+ *
+ * Telemetry only. Nothing branches on it.
+ */
+export type GsapEditBlockDetail =
+  | "provenance-runtime-dynamic"
+  | "unresolved-keyframes"
+  | "unresolved-selector"
+  | "geometry-unresolved-source"
+  | "live-position-no-source-tween"
+  | "no-position-tween"
+  | "live-rotation-no-source-tween"
+  | "live-resize-no-source-tween"
+  | "zero-duration-tween";
+
 export type GsapEditOutcome =
   | {
       status: "persisted";
@@ -22,7 +43,7 @@ export type GsapEditOutcome =
        */
       ownsDragOffset?: boolean;
     }
-  | { status: "blocked"; reason: GsapEditBlockReason };
+  | { status: "blocked"; reason: GsapEditBlockReason; detail?: GsapEditBlockDetail };
 
 const COPY: Record<GsapEditBlockReason, string> = {
   "no-selector": "This layer needs a stable selector before Studio can save the edit.",
@@ -32,25 +53,32 @@ const COPY: Record<GsapEditBlockReason, string> = {
 };
 
 export class GsapEditBlockedError extends Error {
-  constructor(readonly reason: GsapEditBlockReason) {
+  constructor(
+    readonly reason: GsapEditBlockReason,
+    readonly detail?: GsapEditBlockDetail,
+  ) {
     super(COPY[reason]);
     this.name = "GsapEditBlockedError";
   }
 }
 
 export function assertGsapEditPersisted(outcome: GsapEditOutcome): void {
-  if (outcome.status === "blocked") throw new GsapEditBlockedError(outcome.reason);
+  if (outcome.status === "blocked") throw new GsapEditBlockedError(outcome.reason, outcome.detail);
 }
 
 function assertGsapAnimationDirectlyEditable(animation: GsapAnimation): void {
   const editability = editabilityForProvenance(animation.provenance);
   if (editability === "unroll") throw new GsapEditBlockedError("unroll-required");
-  if (
-    editability === "source" ||
-    animation.hasUnresolvedKeyframes ||
-    animation.hasUnresolvedSelector
-  ) {
-    throw new GsapEditBlockedError("source-uneditable");
+  // Same message for all three, but they are different problems: only the first
+  // is genuinely a runtime-computed value.
+  if (editability === "source") {
+    throw new GsapEditBlockedError("source-uneditable", "provenance-runtime-dynamic");
+  }
+  if (animation.hasUnresolvedKeyframes) {
+    throw new GsapEditBlockedError("source-uneditable", "unresolved-keyframes");
+  }
+  if (animation.hasUnresolvedSelector) {
+    throw new GsapEditBlockedError("source-uneditable", "unresolved-selector");
   }
 }
 
@@ -84,7 +112,8 @@ export function directEditOutcomeForProperties(
     }
     return { status: "persisted" };
   } catch (error) {
-    if (isGsapEditBlockedError(error)) return { status: "blocked", reason: error.reason };
+    if (isGsapEditBlockedError(error))
+      return { status: "blocked", reason: error.reason, detail: error.detail };
     throw error;
   }
 }
diff --git a/packages/studio/src/hooks/gsapResizeIntercept.test.ts b/packages/studio/src/hooks/gsapResizeIntercept.test.ts
index 4045b28c8a..2037c7f19f 100644
--- a/packages/studio/src/hooks/gsapResizeIntercept.test.ts
+++ b/packages/studio/src/hooks/gsapResizeIntercept.test.ts
@@ -180,11 +180,15 @@ it("reuses the ownership parse instead of fetching a resolved size group twice",
   );
 });
 
-it("blocks when runtime size motion exists but the authored tween cannot be resolved", async () => {
+function makeBoxSelection(): { el: HTMLElement; selection: DomEditSelection } {
   const el = document.createElement("div");
   el.id = "box";
   document.body.append(el);
-  const selection = { id: "box", selector: "#box", element: el } as DomEditSelection;
+  return { el, selection: { id: "box", selector: "#box", element: el } as DomEditSelection };
+}
+
+it("blocks when runtime size motion exists but the authored tween cannot be resolved", async () => {
+  const { el, selection } = makeBoxSelection();
   const liveSizeTween = {
     targets: () => [el],
     vars: { width: 300, duration: 1 },
@@ -199,7 +203,42 @@ it("blocks when runtime size motion exists but the authored tween cannot be reso
 
   await expect(
     tryGsapResizeIntercept(selection, { width: 344, height: 344 }, [], iframe, commitMutation),
-  ).resolves.toEqual({ status: "blocked", reason: "source-uneditable" });
+  ).resolves.toEqual({
+    status: "blocked",
+    reason: "source-uneditable",
+    detail: "live-resize-no-source-tween",
+  });
+  expect(commitMutation).not.toHaveBeenCalled();
+});
+
+it("blocks a tween with no positive duration instead of committing into it", async () => {
+  const { selection } = makeBoxSelection();
+  // A zero-duration `from` is not an instant hold (those are `set`/`to`), so it
+  // reaches the duration check: a resize has no timeline position to land on.
+  const zeroDurationTween = {
+    id: "#box-size",
+    targetSelector: "#box",
+    propertyGroup: "size",
+    method: "from",
+    position: 0,
+    duration: 0,
+    properties: { width: 150, height: 150 },
+  } as unknown as GsapAnimation;
+  const commitMutation = vi.fn();
+
+  await expect(
+    tryGsapResizeIntercept(
+      selection,
+      { width: 344, height: 344 },
+      [zeroDurationTween],
+      null,
+      commitMutation,
+    ),
+  ).resolves.toEqual({
+    status: "blocked",
+    reason: "source-uneditable",
+    detail: "zero-duration-tween",
+  });
   expect(commitMutation).not.toHaveBeenCalled();
 });
 
diff --git a/packages/studio/src/hooks/gsapResizeIntercept.ts b/packages/studio/src/hooks/gsapResizeIntercept.ts
index 71b1adfba4..9353213dba 100644
--- a/packages/studio/src/hooks/gsapResizeIntercept.ts
+++ b/packages/studio/src/hooks/gsapResizeIntercept.ts
@@ -137,7 +137,12 @@ export async function tryGsapResizeIntercept(
     ? hasNonHoldTweenForElement(iframe, liveSelector, undefined, [...resizeProperties])
     : false;
   if (!anim && hasLiveResizeTween) {
-    return { status: "blocked", reason: "source-uneditable" };
+    // Third twin of the position/rotation cases: a live tween with no source match.
+    return {
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "live-resize-no-source-tween",
+    };
   }
   logResize("intercept-enter", {
     hasScaleGroup,
@@ -194,7 +199,12 @@ export async function tryGsapResizeIntercept(
   }
 
   const tweenDuration = resolveTweenDuration(anim);
-  if (tweenDuration <= 0) return { status: "blocked", reason: "source-uneditable" };
+  if (tweenDuration <= 0) {
+    // The tween exists in source but has no positive duration, so there is no
+    // timeline position at which a resize could land — a different cause from
+    // the live-tween-without-a-source-match cases above.
+    return { status: "blocked", reason: "source-uneditable", detail: "zero-duration-tween" };
+  }
 
   const { activeKeyframePct, setActiveKeyframePct } = usePlayerStore.getState();
   const pct = activeKeyframePct ?? computeCurrentPercentage(selection, anim);
diff --git a/packages/studio/src/hooks/gsapRuntimeBridge.test.ts b/packages/studio/src/hooks/gsapRuntimeBridge.test.ts
index bc79366dfc..62d3cbfa91 100644
--- a/packages/studio/src/hooks/gsapRuntimeBridge.test.ts
+++ b/packages/studio/src/hooks/gsapRuntimeBridge.test.ts
@@ -94,7 +94,11 @@ describe("tryGsapDragIntercept — stale-parse guard (no resurrection after dele
       vi.fn().mockResolvedValue([]),
     );
 
-    expect(result).toEqual({ status: "blocked", reason: "source-uneditable" });
+    expect(result).toEqual({
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "live-position-no-source-tween",
+    });
     expect(commitMutation).not.toHaveBeenCalled();
   });
 
@@ -354,7 +358,11 @@ describe("tryGsapRotationIntercept — instant holds", () => {
         fakeIframe("puck-b", [liveRotation]),
         commitMutation,
       ),
-    ).resolves.toEqual({ status: "blocked", reason: "source-uneditable" });
+    ).resolves.toEqual({
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "live-rotation-no-source-tween",
+    });
     expect(commitMutation).not.toHaveBeenCalled();
   });
 
diff --git a/packages/studio/src/hooks/gsapRuntimeBridge.ts b/packages/studio/src/hooks/gsapRuntimeBridge.ts
index a35fb6d3f1..e66ed6335a 100644
--- a/packages/studio/src/hooks/gsapRuntimeBridge.ts
+++ b/packages/studio/src/hooks/gsapRuntimeBridge.ts
@@ -156,7 +156,13 @@ async function preflightGsapDragIntercept(
   const hasLivePosition = hasNonHoldTweenForElement(iframe, selector, undefined, POSITION_CHANNELS);
 
   if (hasLivePosition && !posAnim) {
-    return { status: "blocked", reason: "source-uneditable" };
+    // GSAP is visibly moving this element but the parser found no position
+    // tween for it — a source-match gap, not necessarily computed source.
+    return {
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "live-position-no-source-tween",
+    };
   }
   if (!posAnim && !writeTargetSelector(selection)) {
     return { status: "blocked", reason: "no-selector" };
@@ -268,7 +274,7 @@ export async function tryGsapDragIntercept(
   }
 
   if (!posAnim) {
-    return { status: "blocked", reason: "source-uneditable" };
+    return { status: "blocked", reason: "source-uneditable", detail: "no-position-tween" };
   }
 
   // Verify the anim ID is still valid in the current file. The React-state
@@ -353,7 +359,12 @@ export async function tryGsapRotationIntercept(
     ? hasNonHoldTweenForElement(iframe, liveSelector, undefined, ROTATION_CHANNELS)
     : false;
   if (!anim && hasLiveRotationTween) {
-    return { status: "blocked", reason: "source-uneditable" };
+    // Rotation twin of the position case above: live tween, no source match.
+    return {
+      status: "blocked",
+      reason: "source-uneditable",
+      detail: "live-rotation-no-source-tween",
+    };
   }
 
   // `angle` is the ABSOLUTE target rotation resolved by the gesture (gsap base +
diff --git a/packages/studio/src/utils/studioSaveDiagnostics.ts b/packages/studio/src/utils/studioSaveDiagnostics.ts
index 865723193c..f4a8c3ebf0 100644
--- a/packages/studio/src/utils/studioSaveDiagnostics.ts
+++ b/packages/studio/src/utils/studioSaveDiagnostics.ts
@@ -165,9 +165,21 @@ export function buildStudioSaveFailureProperties(
     target_id: input.targetId ?? undefined,
     target_selector: input.targetSelector ?? undefined,
     target_source_file: input.targetSourceFile ?? undefined,
+    block_detail: gsapBlockDetail(input.error),
   };
 }
 
+/**
+ * The specific cause behind a blocked GSAP edit. `error_message` only carries
+ * the coarse copy, and one of those strings covers six different situations,
+ * so the message alone cannot say which one a user hit.
+ */
+function gsapBlockDetail(error: unknown): string | undefined {
+  if (!(error instanceof Error) || error.name !== "GsapEditBlockedError") return undefined;
+  const detail = (error as { detail?: unknown }).detail;
+  return typeof detail === "string" ? detail : undefined;
+}
+
 export function trackStudioSaveFailure(input: StudioSaveFailureInput): void {
   trackStudioEvent("save_failure", buildStudioSaveFailureProperties(input));
 }