refactor(confidence-engine): expose canonical graph replacement seam

components/reasoning-workspace.jsx

@@ -1316,6 +1316,8 @@ export default function ReasoningWorkspace({
   onUpdateFindingProposition,
   /* ── v0.49 — done-for-now promotion callback ───────── */
   onSummaryUpdate,
+  /* ── canonical graph-replacement seam (future Re-open) ── */
+  onSituationGraphChange,
 }) {
   const [investigationHistory, setInvestigationHistory] = useState([]);
   const turnCounter = useRef(0);

components/scenario-form.jsx

@@ -814,6 +814,8 @@ export default function ScenarioForm() {
                 onUpdateFindingProposition={updateFindingProposition}
                 /* ── v0.49 — done-for-now promotion seam ─────────── */
                 onSummaryUpdate={handleDoneForNowPromotion}
+                /* ── canonical graph-replacement seam (future Re-open) ── */
+                onSituationGraphChange={(nextGraph) => setResult((prev) => ({ ...(prev ?? {}), situationGraph: nextGraph }))}
                 onRestart={() => {
                   clearInvestigation();
                   setStatus("idle");