feat(credits): solde IA unique (option M), packs Stripe et polish billing

Un pot de crédits global (BASIC 100 / PRO 1 000 / BUSINESS 4 000) remplace
les seaux par fonction côté débit. Packs one-shot S/M/L, admin sans seaux
legacy, usage multi-features, hints de coût, anti-flash thème et hydratation
admin. Inclut aussi le pipeline slides renforcé et la page publique polishée.

memento-note/app/api/billing/create-pack-checkout/route.ts

@@ -0,0 +1,135 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { auth } from '@/auth'
+import { stripe } from '@/lib/stripe'
+import { isBillingEnabled } from '@/lib/billing/stripe-prices'
+import {
+  isCreditPackId,
+  resolvePackPriceId,
+  getCreditPack,
+} from '@/lib/billing/credit-packs'
+import { prisma } from '@/lib/prisma'
+import { z } from 'zod'
+
+const bodySchema = z.object({
+  packId: z.enum(['S', 'M', 'L']),
+})
+
+export async function POST(req: NextRequest) {
+  const session = await auth()
+  if (!session?.user?.id || !session.user.email) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
+
+  if (!(await isBillingEnabled())) {
+    return NextResponse.json({ error: 'Billing is not enabled' }, { status: 403 })
+  }
+
+  const secret = process.env.STRIPE_SECRET_KEY
+  if (!secret || secret === 'sk_test_placeholder') {
+    return NextResponse.json(
+      { error: 'Stripe is not configured (STRIPE_SECRET_KEY missing)' },
+      { status: 503 },
+    )
+  }
+
+  const parsed = bodySchema.safeParse(await req.json())
+  if (!parsed.success || !isCreditPackId(parsed.data.packId)) {
+    return NextResponse.json({ error: 'Invalid pack' }, { status: 400 })
+  }
+
+  const packId = parsed.data.packId
+  const pack = getCreditPack(packId)
+  const userId = session.user.id
+  const userEmail = session.user.email
+
+  try {
+    let priceId: string
+    try {
+      priceId = await resolvePackPriceId(packId)
+    } catch (e) {
+      console.error('[billing/create-pack-checkout] price resolve failed:', e)
+      return NextResponse.json(
+        { error: 'Credit pack price IDs not configured. Set them in Admin > Billing.' },
+        { status: 503 },
+      )
+    }
+
+    if (priceId.startsWith('price_mock_')) {
+      return NextResponse.json(
+        { error: 'Credit pack price IDs not configured. Set them in Admin > Billing.' },
+        { status: 503 },
+      )
+    }
+
+    const subscription = await prisma.subscription.findUnique({ where: { userId } })
+    let customerId = subscription?.stripeCustomerId ?? undefined
+
+    if (customerId && customerId.startsWith('cus_mock')) {
+      customerId = undefined
+    }
+
+    if (!customerId) {
+      const customer = await stripe.customers.create({
+        email: userEmail,
+        metadata: { userId },
+      })
+      customerId = customer.id
+
+      await prisma.subscription.upsert({
+        where: { userId },
+        update: { stripeCustomerId: customerId },
+        create: {
+          userId,
+          stripeCustomerId: customerId,
+          tier: 'BASIC',
+          status: 'ACTIVE',
+          currentPeriodStart: new Date(),
+          currentPeriodEnd: new Date(Date.now() + 30 * 24 * 3600 * 1000),
+        },
+      })
+    }
+
+    const host = req.headers.get('x-forwarded-host') ?? req.headers.get('host') ?? 'localhost:3000'
+    const proto = req.headers.get('x-forwarded-proto') ?? 'http'
+    const origin = `${proto}://${host}`
+
+    const checkoutSession = await stripe.checkout.sessions.create({
+      customer: customerId,
+      mode: 'payment',
+      line_items: [{ price: priceId, quantity: 1 }],
+      success_url: `${origin}/settings/billing?session_id={CHECKOUT_SESSION_ID}&pack=1`,
+      cancel_url: `${origin}/settings/billing?canceled=1`,
+      metadata: {
+        userId,
+        type: 'credit_pack',
+        packId,
+        credits: String(pack.credits),
+      },
+      payment_intent_data: {
+        metadata: {
+          userId,
+          type: 'credit_pack',
+          packId,
+          credits: String(pack.credits),
+        },
+      },
+      customer_update: { address: 'auto' },
+      allow_promotion_codes: true,
+    })
+
+    if (!checkoutSession.url) {
+      return NextResponse.json({ error: 'Checkout session has no URL' }, { status: 500 })
+    }
+
+    return NextResponse.json({
+      url: checkoutSession.url,
+      sessionId: checkoutSession.id,
+      packId,
+      credits: pack.credits,
+    })
+  } catch (error) {
+    console.error('[billing/create-pack-checkout]', error)
+    const msg = error instanceof Error ? error.message : 'Failed to create pack checkout'
+    return NextResponse.json({ error: msg }, { status: 500 })
+  }
+}

memento-note/app/api/billing/status/route.ts

@@ -2,7 +2,6 @@ import { NextRequest, NextResponse } from 'next/server';
 import { auth } from '@/auth';
 import { getUserInfo, getEffectiveTier } from '@/lib/entitlements';
 import { stripe } from '@/lib/stripe';
-import type Stripe from 'stripe';
 import { priceIdToTier, getDynamicPrices, isBillingEnabled } from '@/lib/billing/stripe-prices';
 
 export const dynamic = 'force-dynamic';
@@ -76,6 +75,42 @@ export async function GET(req: NextRequest) {
     const subscription = await prisma.subscription.findUnique({ where: { userId } });
     const prices = await getDynamicPrices();
     const billingEnabled = await isBillingEnabled();
+    const { getPackPublicPrices } = await import('@/lib/billing/credit-packs');
+    const creditPacks = await getPackPublicPrices();
+
+    // Si retour checkout pack : créditer au cas où le webhook n'a pas encore tourné
+    if (sessionId && sessionId.startsWith('cs_')) {
+      try {
+        const checkoutSession = await stripe.checkout.sessions.retrieve(sessionId);
+        if (
+          checkoutSession.mode === 'payment' &&
+          checkoutSession.status === 'complete' &&
+          (checkoutSession.metadata?.type === 'credit_pack' || checkoutSession.metadata?.packId) &&
+          checkoutSession.metadata?.userId === userId
+        ) {
+          const { addPurchasedCredits } = await import('@/lib/credits');
+          const {
+            getCreditPack,
+            isCreditPackId,
+          } = await import('@/lib/billing/credit-packs');
+          const packId = checkoutSession.metadata?.packId;
+          let credits = Number(checkoutSession.metadata?.credits ?? 0);
+          if (packId && isCreditPackId(packId) && (!Number.isFinite(credits) || credits <= 0)) {
+            credits = getCreditPack(packId).credits;
+          }
+          if (Number.isFinite(credits) && credits > 0) {
+            await addPurchasedCredits(userId, credits, {
+              stripeSessionId: checkoutSession.id,
+              packId: packId ?? null,
+              type: 'credit_pack',
+              source: 'billing_status_sync',
+            });
+          }
+        }
+      } catch (packSyncErr) {
+        console.error('[billing/status] pack sync failed:', packSyncErr);
+      }
+    }
 
     return NextResponse.json({
       tier,
@@ -86,6 +121,7 @@ export async function GET(req: NextRequest) {
       cancelAtPeriodEnd: subscription?.cancelAtPeriodEnd ?? false,
       hasStripeSubscription: !!subscription?.stripeSubscriptionId,
       prices,
+      creditPacks,
       billingEnabled,
     });
   } catch (error) {

memento-note/app/api/billing/webhook/route.ts

@@ -6,11 +6,79 @@ import {
   handleSubscriptionDeleted,
   resolveUserIdFromStripeEvent,
 } from '@/lib/billing/sync-subscription-from-stripe';
-import { prisma } from '@/lib/prisma';
+import { addPurchasedCredits } from '@/lib/credits';
+import {
+  getCreditPack,
+  isCreditPackId,
+  resolvePackFromPriceId,
+} from '@/lib/billing/credit-packs';
 import type Stripe from 'stripe';
 
 export const runtime = 'nodejs';
 
+async function fulfillCreditPackPurchase(session: Stripe.Checkout.Session) {
+  if (session.mode !== 'payment') return;
+  if (session.payment_status && session.payment_status !== 'paid' && session.payment_status !== 'no_payment_required') {
+    console.warn('[billing/webhook] pack checkout not paid yet', session.id, session.payment_status);
+    return;
+  }
+
+  const userId = session.metadata?.userId as string | undefined;
+  if (!userId) {
+    console.warn('[billing/webhook] credit pack: no userId', session.id);
+    return;
+  }
+
+  let packId = session.metadata?.packId as string | undefined;
+  let credits = Number(session.metadata?.credits ?? 0);
+
+  if ((!packId || !Number.isFinite(credits) || credits <= 0) && session.line_items == null) {
+    try {
+      const full = await stripe.checkout.sessions.retrieve(session.id, {
+        expand: ['line_items.data.price'],
+      });
+      const priceId = full.line_items?.data?.[0]?.price?.id;
+      if (priceId) {
+        const resolved = await resolvePackFromPriceId(priceId);
+        if (resolved) {
+          packId = resolved.packId;
+          credits = resolved.credits;
+        }
+      }
+    } catch (err) {
+      console.error('[billing/webhook] expand line_items failed', err);
+    }
+  }
+
+  if (packId && isCreditPackId(packId) && (!Number.isFinite(credits) || credits <= 0)) {
+    credits = getCreditPack(packId).credits;
+  }
+
+  if (!Number.isFinite(credits) || credits <= 0) {
+    console.warn('[billing/webhook] credit pack: invalid credits', session.id, { packId, credits });
+    return;
+  }
+
+  const result = await addPurchasedCredits(userId, credits, {
+    stripeSessionId: session.id,
+    packId: packId ?? null,
+    type: 'credit_pack',
+    paymentIntent:
+      typeof session.payment_intent === 'string'
+        ? session.payment_intent
+        : session.payment_intent?.id ?? null,
+  });
+
+  if (result.applied) {
+    console.info('[billing/webhook] credited pack', {
+      userId,
+      credits: result.units,
+      packId,
+      sessionId: session.id,
+    });
+  }
+}
+
 export async function POST(req: NextRequest) {
   const body = await req.text();
   const headersList = await headers();
@@ -49,6 +117,11 @@ export async function POST(req: NextRequest) {
           } else {
             console.warn('[billing/webhook] checkout.session.completed: no userId in metadata', session.id);
           }
+        } else if (
+          session.mode === 'payment' &&
+          (session.metadata?.type === 'credit_pack' || session.metadata?.packId)
+        ) {
+          await fulfillCreditPackPurchase(session);
         }
         break;
       }