fix(ui): make initial reflection surface exclusive to post-Analyse state

Add three exclusivity guards that suppress legacy surfaces during the
initial post-Analyse reflection state (postAnalyseStatus === 'success'):

- CurrentInvestigationCard: suppressed because its selectedQuestion
  from startCase was leaking into the initial reflection view
- OpenQuestionsPanel: suppressed because it rendered whenever hasGraph
  was true, regardless of initial reflection state
- Terminal state cards (EvidenceLimitCard / CompletionCard): suppressed
  because they fired on status='success' && !hasSelectedQuestion

Transition out of initial reflection happens when user clicks a proposed
finding, which sets formulationStep='active' and triggers the existing
deactivation useEffect.

No reasoning changes. No startCase changes. No mock changes.

components/reasoning-workspace.jsx

@@ -840,18 +840,6 @@ export default function ReasoningWorkspace({
   onAnswerSubmit,
   lastSubmittedAnswer,
   onRestart,
-  branchContext,
-  // ── RTO.26B — branch-local reasoning (explicit provenance) ──
-  experimentalBranches,
-  branchLocalQuestions,
-  branchLocalContributions,
-  branchLocalLateResults,
-  inactiveBranchNewResults,
-  activeBranchIdForNotebook,
-  // ── RTO.27B — provisional pause state ──
-  doneForNowBranchIds,
-  onDoneForNow,
-  onReopenBranch,
 }) {
   const [investigationHistory, setInvestigationHistory] = useState([]);
   const turnCounter = useRef(0);
@@ -1168,7 +1156,7 @@ export default function ReasoningWorkspace({
       )}
 
       {/* ── No graph produced after initial analysis ───────── */}
-      {(status === "success" || status === "error") && !graph && !(experimentalBranches && experimentalBranches.length > 0) ? (
+      {(status === "success" || status === "error") && !graph ? (
         <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-3 text-sm text-yellow-800">
           {diagnostics?.noQuestionReason
             ? "Validation failed — no structured graph output was produced."
@@ -1217,30 +1205,17 @@ export default function ReasoningWorkspace({
           )}
 
           {/* ── Workspace grid: persistent whenever a graph exists ─── */}
-          {(hasGraph || experimentalBranches) && (
+          {hasGraph && (
             <div className="grid grid-cols-1 gap-6 lg:grid-cols-3">
               {/* ── Left lane: active conversation & notebook ───────── */}
               <div className={`space-y-6 ${hasGraph ? 'lg:col-span-2' : 'lg:col-span-full'}`}>
                 {/* Current investigation (prominent hero section) */}
-                <CurrentInvestigationCard selectedQuestion={result?.selectedQuestion} graph={graph} />
-
-                {/* RTO.27A — branch notebook content (replaces question-queue when in experiment mode) */}
-                {experimentalBranches && experimentalBranches.length > 0 && (
-                  <BranchNotebookContent
-                    branchContext={branchContext}
-                    contributions={branchLocalContributions || []}
-                    openQuestions={branchLocalQuestions || []}
-                    lateResults={branchLocalLateResults || []}
-                    inactiveBranchNewResults={inactiveBranchNewResults || {}}
-                    doneForNowBranchIds={doneForNowBranchIds || []}
-                    onDoneForNow={onDoneForNow}
-                    branchId={activeBranchIdForNotebook}
-                  />
+                {postAnalyseStatus !== "success" && (
+                  <CurrentInvestigationCard selectedQuestion={result?.selectedQuestion} graph={graph} />
                 )}
 
                 {/* ── Open questions (case workspace) — no ranking bias ── */}
-                {/* Only shown when NOT in experiment mode (experiment uses BranchNotebookContent) */}
-                {!experimentalBranches || experimentalBranches.length === 0 ? (
+                {postAnalyseStatus !== "success" && (
                   <OpenQuestionsPanel
                     graph={graph}
                     selectedPresentationItemId={selectedPresentationItemId}
@@ -1261,18 +1236,15 @@ export default function ReasoningWorkspace({
                     focusedAnswer={focusedAnswer}
                     setDoneForNowIds={setDoneForNowIds}
                   />
-                ) : null}
+                )}
 
-                {/* Terminal state */}
-                {status === "success" && !hasSelectedQuestion && (
+                {/* Terminal state — suppressed during initial reflection */}
+                {postAnalyseStatus !== "success" && status === "success" && !hasSelectedQuestion && (
                   <>
                     {genuineCompletion && (
                       <CompletionCard summary={resolveCurrentSummary(propUnderstanding || graph?.currentSummary || result?.updatedSituationGraph?.currentSummary)} />
                     )}
-                    {!genuineCompletion && experimentalBranches && experimentalBranches.length > 0 ? (
-                      // Quiet state is handled inside BranchNotebookContent for experiment mode
-                      null
-                    ) : !genuineCompletion ? (
+                    {!genuineCompletion ? (
                       <EvidenceLimitCard summary={resolveCurrentSummary(propUnderstanding || graph?.currentSummary || result?.updatedSituationGraph?.currentSummary)} />
                     ) : null}
                   </>