fix(studio/sdkShadow): catch dispatch errors, return dispatch_error mismatch

Wrap the dispatch loop in try/catch so a throwing SDK dispatch never
propagates to Studio UX. Returns dispatched:false with kind="dispatch_error"
and the error message for telemetry. One new TDD test (RED→GREEN verified).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: vanceingalls

packages/studio/src/utils/sdkShadow.test.ts

@@ -120,4 +120,27 @@ describe("sdkShadowDispatch (integration)", () => {
 
     expect(session.getElement("hf-box")?.attributes["data-name"]).toBe("hero");
   });
+
+  it("returns dispatch_error when dispatch throws — does not propagate", async () => {
+    const { sdkShadowDispatch } = await import("./sdkShadow");
+    const session = await openComposition(BASE_HTML);
+    // Poison dispatch so it throws on any call
+    session.dispatch = () => {
+      throw new Error("sdk internal error");
+    };
+
+    const ops: PatchOperation[] = [{ type: "inline-style", property: "color", value: "red" }];
+    let result: ReturnType<typeof sdkShadowDispatch> | undefined;
+    expect(() => {
+      result = sdkShadowDispatch(session, "hf-box", ops);
+    }).not.toThrow();
+
+    expect(result!.dispatched).toBe(false);
+    expect(result!.mismatches).toHaveLength(1);
+    expect(result!.mismatches[0]).toMatchObject<SdkShadowMismatch>({
+      kind: "dispatch_error",
+      hfId: "hf-box",
+      error: expect.stringContaining("sdk internal error"),
+    });
+  });
 });

packages/studio/src/utils/sdkShadow.ts

@@ -57,11 +57,12 @@ export function patchOpsToSdkEditOps(hfId: string, ops: PatchOperation[]): EditO
 // ─── Shadow result types ──────────────────────────────────────────────────────
 
 export interface SdkShadowMismatch {
-  kind: "element_not_found" | "value_mismatch";
+  kind: "element_not_found" | "value_mismatch" | "dispatch_error";
   hfId: string;
   property?: string;
   expected?: string | null;
   actual?: string | null | undefined;
+  error?: string;
 }
 
 export interface SdkShadowResult {
@@ -149,8 +150,15 @@ export function sdkShadowDispatch(
   if (!session.getElement(hfId)) {
     return { dispatched: false, mismatches: [{ kind: "element_not_found", hfId }] };
   }
-  for (const op of patchOpsToSdkEditOps(hfId, ops)) {
-    session.dispatch(op);
+  try {
+    for (const op of patchOpsToSdkEditOps(hfId, ops)) {
+      session.dispatch(op);
+    }
+  } catch (err) {
+    return {
+      dispatched: false,
+      mismatches: [{ kind: "dispatch_error", hfId, error: String(err) }],
+    };
   }
   const flat = flattenSnapshot(session.getElement(hfId));
   const mismatches = ops