fix(ui): preserve investigation workspace across no-question states

components/reasoning-workspace.jsx

@@ -658,16 +658,23 @@ export default function ReasoningWorkspace({
         </div>
       ) : (
         <>
-          {hasSelectedQuestion && (
+          {/* ── Workspace grid: persistent whenever a graph exists ─── */}
+          {hasGraph && (
             <div className="grid grid-cols-1 gap-6 lg:grid-cols-3">
               {/* ── Left lane: active conversation & notebook ───────── */}
               <div className="space-y-6 lg:col-span-2">
-                <CurrentInvestigationCard selectedQuestion={selectedQ} graph={graph} />
+                {/* Active question — only when there is one */}
+                {hasSelectedQuestion && (
+                  <>
+                    <CurrentInvestigationCard selectedQuestion={selectedQ} graph={graph} />
 
-                {updateStatus === "success" && !isUpdating && (
-                  <UpdateAcknowledgement updateResult={result} />
+                    {updateStatus === "success" && !isUpdating && (
+                      <UpdateAcknowledgement updateResult={result} />
+                    )}
+                  </>
                 )}
 
+                {/* Answer form — only when a question is active and not loading */}
                 {!isUpdating && canAnswer && (
                   <form onSubmit={handleUpdateCaptureAndSubmit} className="space-y-4 rounded-lg border border-gray-200 bg-white p-5">
                     <div>