W4: graph store + emission + home graph view

app/api/graph/route.ts

@@ -0,0 +1,15 @@
+import { foldStaleChats, graphSnapshot } from "@/src/core/graph";
+
+/**
+ * The home graph view's data endpoint (W4; vision §1 "Home page"). Folds any
+ * chat whose updatedAt outstrips its emission checkpoint first (partial
+ * sessions deposit value), then returns nodes, edges, derived node states,
+ * and the session titles/provenance for node click-through.
+ */
+
+export const dynamic = "force-dynamic";
+
+export async function GET() {
+	foldStaleChats();
+	return Response.json(graphSnapshot());
+}