feat(confidence-engine): v0.60j preserve investigation on restart

lib/storage/investigation-storage.js

@@ -2,7 +2,7 @@
 // Owns the canonical identity contract: snapshot.id is the sole save identity.
 // Delegates to the concrete localStorage provider internally.
 
-import { loadInvestigation as _load, saveInvestigation as _save, clearInvestigation as _clear, listInvestigations as _list } from "./providers/local-storage.js";
+import { loadInvestigation as _load, saveInvestigation as _save, clearInvestigation as _clear, listInvestigations as _list, restartInvestigation as _restart } from "./providers/local-storage.js";
 
 /**
  * Canonical save contract: snapshot.id is the sole identity authority.
@@ -40,3 +40,15 @@ export function clearInvestigation(id) {
 export function listInvestigations() {
   return _list();
 }
+
+/**
+ * Semantic restart: reset reasoning/report state within the Investigation container.
+ *
+ * The Investigation is NOT deleted or replaced. Its durable `id` and `scenario` (container)
+ * are preserved. All reasoning-state fields are cleared so a new clean pass can begin.
+ *
+ * Missing/invalid id → silently no-op (does NOT fall back to legacy singleton).
+ */
+export function restartInvestigation(id) {
+  return _restart(id);
+}

lib/storage/providers/local-storage.js

@@ -175,6 +175,41 @@ export function listInvestigations() {
   return summaries;
 }
 
+// ── restartInvestigation (semantic reset within container) ───────────
+
+/**
+ * Resets the Investigation to a clean state suitable for a new reasoning pass.
+ *
+ * Preserved: id, scenario, schemaVersion (container-level identity/framing).
+ * Reset: situationGraph → null, selectedQuestion → null, summary → null,
+ *        focusedContributions → [], findings → [], investigationReport → null,
+ *        investigationRevision → 0, updatedAt → new ISO timestamp.
+ */
+export function restartInvestigation(id) {
+  const storage = _getTargetStorage();
+  if (!storage) return;
+
+  try {
+    const key = id != null ? `${INVESTIGATION_PREFIX}${id}` : CANONICAL_KEY;
+    const raw = safeGet(storage, key);
+    if (raw === null) return; // nothing to restart
+    const record = JSON.parse(raw);
+    if (!isPlainObject(record)) return;
+
+    // Preserve container fields, reset reasoning-state fields
+    record.situationGraph = null;
+    record.selectedQuestion = null;
+    record.summary = null;
+    record.focusedContributions = [];
+    record.findings = [];
+    record.investigationReport = null;
+    record.investigationRevision = 0;
+    record.updatedAt = new Date().toISOString();
+
+    _persist(storage, key, JSON.stringify(record));
+  } catch (_) { /* storage errors must not crash caller */ }
+}
+
 // ── internals ────────────────────────────────────────────────────────
 
 function _persist(storage, key, value) {