feat: implement bff layer

app/essays/[slug]/page.tsx

@@ -10,8 +10,7 @@ import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
 import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
-import { prisma } from "@/lib/db";
-import type { JsonValue } from "@prisma/client/runtime/library";
+import { bff, bffList } from "@/lib/bff";
 
 // ---------------------------------------------------------------------------
 // HTML sanitisation (same pattern used across all readers)
@@ -31,25 +30,6 @@ function sanitizeHtml(html: string): string {
   return clean;
 }
 
-function normalizeParagraphs(paragraphs: string[] | JsonValue): string[] {
-  let result: string[];
-
-  if (typeof paragraphs === "string") {
-    try {
-      const parsed = JSON.parse(paragraphs);
-      result = Array.isArray(parsed) ? parsed : [paragraphs];
-    } catch {
-      result = [paragraphs];
-    }
-  } else if (Array.isArray(paragraphs)) {
-    result = paragraphs as string[];
-  } else {
-    result = [];
-  }
-
-  return result.map(sanitizeHtml);
-}
-
 // ---------------------------------------------------------------------------
 // Data fetching
 // ---------------------------------------------------------------------------
@@ -69,7 +49,14 @@ type SidebarItem = {
 };
 
 async function getEssay(slug: string): Promise<EssayData | null> {
-  const doc = await prisma.essay.findUnique({ where: { slug } });
+  const doc = await bff<{
+    slug: string;
+    title: string;
+    author: string;
+    year: number | null;
+    group: string | null;
+    paragraphs: string[];
+  }>(`/essays/${slug}`);
   if (!doc) return null;
   return {
     slug: doc.slug,
@@ -77,15 +64,12 @@ async function getEssay(slug: string): Promise<EssayData | null> {
     author: doc.author,
     year: doc.year,
     group: doc.group,
-    paragraphs: normalizeParagraphs(doc.paragraphs),
+    paragraphs: (doc.paragraphs ?? []).map(sanitizeHtml),
   };
 }
 
 async function getEssaySidebar(): Promise<SidebarItem[]> {
-  return prisma.essay.findMany({
-    orderBy: [{ group: "asc" }, { order: "asc" }],
-    select: { slug: true, title: true },
-  });
+  return bffList<SidebarItem>("/essays");
 }
 
 // ---------------------------------------------------------------------------