Public rule and detail page added

lib/server/publishedRules.ts

@@ -0,0 +1,48 @@
+import { prisma } from "./db";
+import { isDatabaseConfigured } from "./env";
+
+/**
+ * Public fields safe to expose via the unauthenticated rule detail surfaces
+ * (`GET /api/rules/[id]` and `/rules/[id]`). `userId` is intentionally omitted.
+ */
+const PUBLISHED_RULE_PUBLIC_SELECT = {
+  id: true,
+  title: true,
+  summary: true,
+  document: true,
+  createdAt: true,
+  updatedAt: true,
+} as const;
+
+export type PublicPublishedRule = {
+  id: string;
+  title: string;
+  summary: string | null;
+  document: unknown;
+  createdAt: Date;
+  updatedAt: Date;
+};
+
+/**
+ * Fetch a single published rule by id for public read surfaces.
+ *
+ * Returns `null` when the database is not configured, the id does not match
+ * any row, or the query throws — callers render a 404 in all missing cases
+ * and are expected to surface the "DB not configured" state separately if
+ * they care about distinguishing it (the API route does; the page does not).
+ */
+export async function getPublicPublishedRuleById(
+  id: string,
+): Promise<PublicPublishedRule | null> {
+  if (!isDatabaseConfigured()) return null;
+  if (typeof id !== "string" || id.trim() === "") return null;
+  try {
+    const rule = await prisma.publishedRule.findUnique({
+      where: { id },
+      select: PUBLISHED_RULE_PUBLIC_SELECT,
+    });
+    return rule;
+  } catch {
+    return null;
+  }
+}