feat: harden runtime readiness and session workflow

frontend/src/widgets/FreetextWidget.tsx

@@ -3,6 +3,9 @@ import type { WidgetProps } from "./types";
 
 export function FreetextWidget({ descriptor, onRespond }: WidgetProps) {
   const [text, setText] = useState("");
+  function submit() {
+    if (text.trim()) onRespond({ id: descriptor.id, kind: "freetext", text });
+  }
   return (
     <div className="space-y-3 rounded-xl border border-border/70 bg-card p-4 shadow-sm">
       {descriptor.title && (
@@ -11,14 +14,16 @@ export function FreetextWidget({ descriptor, onRespond }: WidgetProps) {
         </p>
       )}
       <textarea
-        className="min-h-24 w-full resize-y rounded-lg border border-input bg-card p-3 text-sm shadow-xs outline-none transition-[border-color,box-shadow] focus:border-primary/50 focus:ring-2 focus:ring-ring/20"
+        data-awaiting-input="true"
+        className="thot-awaiting-input min-h-24 w-full resize-y rounded-lg border p-3 text-sm shadow-xs outline-none transition-[border-color,box-shadow]"
         value={text}
         onChange={(e) => setText(e.target.value)}
+        onKeyDown={(e) => { if (e.key === "Enter" && !e.shiftKey) { e.preventDefault(); submit(); } }}
         placeholder="Type your answer…"
       />
       <button
         className="rounded-md bg-primary px-4 py-2 text-sm font-semibold text-primary-foreground shadow-xs transition-colors hover:bg-[oklch(var(--primary-hover))]"
-        onClick={() => onRespond({ id: descriptor.id, kind: "freetext", text })}
+        onClick={submit}
       >
         Send
       </button>

frontend/src/widgets/ReservedControls.tsx

@@ -28,9 +28,11 @@ export function ReservedControls({
       {otherOpen && (
         <div className="flex flex-col gap-2">
           <textarea
-            className="min-h-20 w-full resize-y rounded-lg border border-input bg-card p-3 text-sm shadow-xs outline-none transition-[border-color,box-shadow] focus:border-primary/50 focus:ring-2 focus:ring-ring/20"
+            data-awaiting-input="true"
+            className="thot-awaiting-input min-h-20 w-full resize-y rounded-lg border p-3 text-sm shadow-xs outline-none transition-[border-color,box-shadow]"
             value={text}
             onChange={(e) => setText(e.target.value)}
+            onKeyDown={(e) => { if (e.key === "Enter" && !e.shiftKey && text.trim()) { e.preventDefault(); onControl("freetext", text); } }}
             placeholder="Describe your alternative…"
           />
           <button