refactor(confidence-engine): migrate scenario persistence to storage provider

components/scenario-form.jsx

@@ -6,6 +6,7 @@ import DiagnosticsView from "@/components/diagnostics-view";
 import ReasoningWorkspace, { LoadingOverlay, ContinueLaterBanner } from "@/components/reasoning-workspace";
 import { mockFetch, AVAILABLE_SCENARIOS } from "@/lib/mocks/confidence-engine/mock-client";
 import { deriveFindingsFromContributions, normalizeFindings } from "@/lib/graph/finding-helpers";
+import { loadInvestigation, saveInvestigation, clearInvestigation } from "@/lib/storage/investigation-storage";
 
 /* Compile-time env resolution — NEXT_PUBLIC_ vars are injected by Next.js at build */
 const MOCK_ENABLED = process.env.NEXT_PUBLIC_CONFIDENCE_ENGINE_MOCKS === "true";
@@ -192,26 +193,6 @@ export function UpdateErrorPanel({ updateError }) {
 
 export { INITIAL_MESSAGES, UPDATE_MESSAGES, useLoadingStatus };
 
-// ── Session key ────────────────────────────────────────────────
-const SESSION_KEY = "confidence-engine-session";
-
-function getSession() {
-  if (typeof sessionStorage === "undefined") return null;
-  try {
-    const raw = sessionStorage.getItem(SESSION_KEY);
-    return raw ? JSON.parse(raw) : null;
-  } catch (_) { return null; }
-}
-
-function saveSession(state) {
-  if (typeof sessionStorage === "undefined") return;
-  try { sessionStorage.setItem(SESSION_KEY, JSON.stringify(state)); } catch (_) {}
-}
-
-function clearSession() {
-  if (typeof sessionStorage === "undefined") return;
-  try { sessionStorage.removeItem(SESSION_KEY); } catch (_) {}
-}
 
 /**
  * Derives whether the current component state represents a valid investigation
@@ -310,10 +291,10 @@ export default function ScenarioForm() {
   // Delegated to the exported utility below.
   const validCtx = hasValidInvestigationContext(result, status, scenario);
 
-  /* Restore persisted session on mount (Phase 3) ─────────── */
+  /* Restore persisted session on mount ─────────── */
   useEffect(() => {
     if (typeof window === "undefined") return;
-    const saved = getSession();
+    const saved = loadInvestigation();
     if (!saved) return;
 
     const hasGraph = Boolean(saved.situationGraph);
@@ -407,7 +388,7 @@ export default function ScenarioForm() {
         setCurrentUnderstanding(data.summary ?? null);
         const normalised = normaliseStartResult(data);
         setResult(normalised);
-        saveSession({ scenario, situationGraph: normalised.situationGraph, selectedQuestion: normalised.selectedQuestion, summary: data.summary ?? null, updatedAt: new Date().toISOString(), focusedContributions, findings: [] });
+        saveInvestigation({ scenario, situationGraph: normalised.situationGraph, selectedQuestion: normalised.selectedQuestion, summary: data.summary ?? null, updatedAt: new Date().toISOString(), focusedContributions, findings: [] });
       } else {
         setStatus("error");
         setCurrentUnderstanding(data.summary ?? null);
@@ -480,7 +461,7 @@ export default function ScenarioForm() {
         }));
         setAnswer("");
         // Persist after successful update turn — include findings
-        saveSession({ scenario, situationGraph: outcome.updatedSituationGraph, selectedQuestion: normaliseUpdateSelectedQuestion(outcome.selectedQuestion), summary: outcome.summary ?? currentUnderstanding, updatedAt: new Date().toISOString(), focusedContributions, findings: newFindings });
+        saveInvestigation({ scenario, situationGraph: outcome.updatedSituationGraph, selectedQuestion: normaliseUpdateSelectedQuestion(outcome.selectedQuestion), summary: outcome.summary ?? currentUnderstanding, updatedAt: new Date().toISOString(), focusedContributions, findings: newFindings });
       } else {
         setUpdateStatus("error");
         setUpdateError(outcome);
@@ -642,7 +623,7 @@ export default function ScenarioForm() {
                 onUpdateFindingDisposition={updateFindingDisposition}
                 onUpdateFindingProposition={updateFindingProposition}
                 onRestart={() => {
-                  clearSession();
+                  clearInvestigation();
                   setStatus("idle");
                   setResult(null);
                   setAnswer("");
@@ -662,7 +643,7 @@ export default function ScenarioForm() {
 
       {/* ── Continue later banner when session was restored ── */}
       {status === "success" && result?.updatedAt && (
-        <ContinueLaterBanner onRestart={() => { clearSession(); setStatus("idle"); setResult(null); setAnswer(""); setUpdateStatus("idle"); setCurrentUnderstanding(null); setFocusedContributions([]); setFindings([]); }} />
+        <ContinueLaterBanner onRestart={() => { clearInvestigation(); setStatus("idle"); setResult(null); setAnswer(""); setUpdateStatus("idle"); setCurrentUnderstanding(null); setFocusedContributions([]); setFindings([]); }} />
       )}
 
       {/* Reset button after successful analysis */}
@@ -670,7 +651,7 @@ export default function ScenarioForm() {
         <div className="text-center">
           <button
             onClick={() => {
-              clearSession();
+              clearInvestigation();
               setScenario("");
               setStatus("idle");
               setResult(null);