feat(confidence-engine): use server investigation persistence

lib/storage/providers/local-storage.js

@@ -4,6 +4,8 @@ const CANONICAL_KEY  = "confidence-engine-investigation";
 const LEGACY_KEY     = "confidence-engine-session";
 const SCHEMA_VERSION = 1;
 
+import { restartSnapshot } from "../restart-investigation.js";
+
 // Multi-Investigation key prefix (v0.60c)
 const INVESTIGATION_PREFIX = "confidence-engine-investigation:";
 
@@ -196,17 +198,7 @@ export function restartInvestigation(id) {
     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));
+    _persist(storage, key, JSON.stringify(restartSnapshot(record)));
   } catch (_) { /* storage errors must not crash caller */ }
 }
 

lib/storage/providers/server-http.js

@@ -0,0 +1,41 @@
+async function request(path, options) {
+  const response = await fetch(path, options);
+  const body = await response.json().catch(() => ({}));
+  if (!response.ok) {
+    throw new Error(body.error || "Investigation persistence request failed");
+  }
+  return body;
+}
+
+export async function saveInvestigation(snapshot, id) {
+  const body = await request("/api/investigations", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ id, snapshot }),
+  });
+  return body.snapshot ?? null;
+}
+
+export async function loadInvestigation(id) {
+  const url = `/api/investigations/${encodeURIComponent(id)}`;
+  const response = await fetch(url);
+  if (!response.ok) {
+    if (response.status === 404) return null;
+    const body = await response.json().catch(() => ({}));
+    throw new Error(body.error || "Investigation persistence request failed");
+  }
+  const body = await response.json();
+  return body.snapshot ?? null;
+}
+
+export async function listInvestigations() {
+  const body = await request("/api/investigations");
+  return body.investigations ?? [];
+}
+
+export async function restartInvestigation(id) {
+  const body = await request(`/api/investigations/${encodeURIComponent(id)}/restart`, {
+    method: "POST",
+  });
+  return body.snapshot ?? null;
+}