diff --git a/desktop/src/features/workflows/ui/WorkflowStepCard.tsx b/desktop/src/features/workflows/ui/WorkflowStepCard.tsx
index 3b65647d4..bd690d49b 100644
--- a/desktop/src/features/workflows/ui/WorkflowStepCard.tsx
+++ b/desktop/src/features/workflows/ui/WorkflowStepCard.tsx
@@ -33,6 +33,13 @@ function BackendSupportHint({ action }: { action: StepFormState["action"] }) {
           records are not persisted yet.
         </p>
       );
+    case "add_reaction":
+      return (
+        <p className="rounded-md border border-amber-500/30 bg-amber-500/10 px-2 py-1 text-xs text-amber-700">
+          Backend note: `add_reaction` is not executed yet, so runs fail at this
+          step.
+        </p>
+      );
     default:
       return null;
   }
@@ -254,7 +261,8 @@ function StepConfigFields({
       );
     case "add_reaction":
       return (
-        <div className="space-y-1.5">
+        <div className="space-y-2">
+          <BackendSupportHint action={step.action} />
           <FieldLabel htmlFor={`${prefix}-emoji`}>Emoji</FieldLabel>
           <WorkflowEmojiField
             ariaLabel="Choose reaction emoji"
diff --git a/desktop/tests/e2e/workflows.spec.ts b/desktop/tests/e2e/workflows.spec.ts
index 4f8ce6906..1953ac894 100644
--- a/desktop/tests/e2e/workflows.spec.ts
+++ b/desktop/tests/e2e/workflows.spec.ts
@@ -303,6 +303,9 @@ test("chooses an add-reaction step emoji with the app emoji picker", async ({
   await page.getByRole("menuitem", { name: "Add Reaction" }).click();
 
   const inspector = dialog.getByTestId("workflow-node-inspector");
+  await expect(inspector).toContainText(
+    "Backend note: `add_reaction` is not executed yet, so runs fail at this step.",
+  );
   const stepEmoji = inspector.getByRole("button", {
     name: "Choose reaction emoji",
   });