Add consented social milestone posting

src/app/(main)/api/social-milestones/route.ts

@@ -0,0 +1,41 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { db } from '@/lib/db';
+import { getSessionUserId } from '@/lib/session';
+import { buildMilestoneCard, buildMilestonePost, milestoneThreshold, socialLocale } from '@/lib/social-milestones';
+
+export const dynamic = 'force-dynamic';
+
+// Returns at most one item. A missing response is treated as no consent, never as approval.
+export async function GET(request: NextRequest) {
+  const userId = getSessionUserId();
+  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+
+  const user = await db.user.findUnique({
+    where: { id: userId }, select: { socialPromptOptOut: true, xHandle: true, primaryUseCase: true },
+  });
+  if (!user || user.socialPromptOptOut) return NextResponse.json({ milestone: null });
+
+  const milestone = await db.socialMilestone.findFirst({
+    where: { userId, status: { in: ['detected', 'shown'] } },
+    orderBy: { detectedAt: 'asc' },
+    include: { qr: { select: { title: true } } },
+  });
+  if (!milestone) return NextResponse.json({ milestone: null });
+
+  if (milestone.status === 'detected') {
+    await db.socialMilestone.update({ where: { id: milestone.id }, data: { status: 'shown', shownAt: new Date() } });
+  }
+  const threshold = milestoneThreshold(milestone.kind);
+  if (!threshold) return NextResponse.json({ milestone: null });
+  const locale = socialLocale(request.nextUrl.searchParams.get('locale'));
+
+  return NextResponse.json({
+    milestone: {
+      id: milestone.id, qrTitle: milestone.qr.title, threshold,
+      defaultXHandle: user.xHandle,
+      language: locale,
+      preview: buildMilestonePost(user.primaryUseCase, threshold, null, locale),
+      card: buildMilestoneCard(user.primaryUseCase, threshold, locale),
+    },
+  });
+}