security: fix full audit findings (v0.32.0)

Full list of the audit's confirmed findings and their fixes:

- Stored XSS via unescaped JSON-LD on the public recipe page
  (app/r/[id]/page.tsx) — escape < before injecting.
- CSP allowed unsafe-eval in production — now dev-only (Next prod
  never eval()s; only its HMR does).
- avatarUrl accepted any URL with no ownership check — now takes an
  avatarKey issued by avatar-presign, validated server-side, same
  pattern as recipe/review photos.
- No session revocation on password change/reset — both now revoke
  other sessions (revokeOtherSessions: true, revokeSessionsOnPasswordReset).
- Rate-limit bypass via spoofable X-Forwarded-For — take the last
  (proxy-appended) hop instead of the first (client-supplied) one,
  matching the single-Traefik-hop topology.
- Webhook signing secrets stored plaintext — now AES-256-GCM
  encrypted like every other secret in this app, with a legacy-
  plaintext fallback for pre-existing rows (bare hex has no ":", our
  ciphertext format always does).
- Better Auth's own rate limiter defaulted to in-memory storage,
  ineffective across replicas — now backed by the same Redis as
  lib/rate-limit.ts (secondaryStorage), with storeSessionInDatabase
  explicit so session storage itself doesn't move as a side effect.
- Presigned upload URLs didn't bind the declared file size to the
  actual upload, letting a client under-declare size (and quota
  charge) then PUT an arbitrarily large object — switched to S3
  presigned POST with a signed content-length-range condition,
  enforced by the storage server itself.
- generateMetadata() on the recipe page skipped the visibility
  filter the page body uses, leaking a private recipe's title via
  <title> to any signed-in user with the id.
- Block/unblock had no rate limit, unlike follow/unfollow.
- AI quota was charged even when a user's own BYOK key was used
  (their own credentials/billing) — added an isByok flag through
  the config-resolution chain and skip the charge when set. Also
  wired BYOK into generate/generate-from-idea/translate/import-url,
  which never looked it up at all before.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/ai/ai-error.ts

@@ -47,26 +47,33 @@ type QuotaResult<T> = { ok: true; data: T } | { ok: false; response: NextRespons
  * throws — so a provider outage never silently burns a user's quota.
  * Centralizes the TierLimitError → 403 and AI-failure → clean-JSON mapping
  * that every AI route needs instead of repeating try/catch per route.
+ *
+ * Pass `skipQuota: true` when the resolved AiConfig used the caller's own
+ * BYOK key (config.isByok) — it's their own credentials/billing, so it
+ * shouldn't count against the platform's monthly AI-call limit.
  */
 export async function withAiQuota<T>(
   userId: string,
   tier: "free" | "pro",
-  fn: () => Promise<T>
+  fn: () => Promise<T>,
+  opts?: { skipQuota?: boolean }
 ): Promise<QuotaResult<T>> {
-  try {
-    await checkAndIncrementTierLimit(userId, tier, "aiCall");
-  } catch (err) {
-    if (err instanceof TierLimitError) {
-      return { ok: false, response: NextResponse.json({ error: "AI call limit reached for your tier" }, { status: 403 }) };
+  if (!opts?.skipQuota) {
+    try {
+      await checkAndIncrementTierLimit(userId, tier, "aiCall");
+    } catch (err) {
+      if (err instanceof TierLimitError) {
+        return { ok: false, response: NextResponse.json({ error: "AI call limit reached for your tier" }, { status: 403 }) };
+      }
+      throw err;
     }
-    throw err;
   }
 
   try {
     const data = await fn();
     return { ok: true, data };
   } catch (err) {
-    await refundAiCall(userId);
+    if (!opts?.skipQuota) await refundAiCall(userId);
     return { ok: false, response: aiErrorResponse(err) };
   }
 }

apps/web/lib/ai/factory.ts

@@ -8,6 +8,9 @@ export type AiConfig = {
   provider?: AiProvider;
   model?: string;
   apiKey?: string;
+  /** True when apiKey is the caller's own BYOK key — their own credentials
+   * and billing, so platform AI-call quota shouldn't be charged for it. */
+  isByok?: boolean;
 };
 
 export function resolveModel(config: AiConfig = {}): LanguageModel {

apps/web/lib/ai/resolve-user-key.ts

@@ -44,7 +44,7 @@ export async function withUserKey(userId: string, config: AiConfig): Promise<AiC
 
   try {
     const apiKey = decrypt(row.encryptedKey);
-    return { ...config, apiKey };
+    return { ...config, apiKey, isByok: true };
   } catch {
     throw new ByokDecryptError(provider);
   }
@@ -81,7 +81,7 @@ export async function getDefaultProviderWithKey(userId: string, useCase?: ModelU
     const row = keys.find((k) => k.provider === p);
     if (row) {
       try {
-        return { provider: p, apiKey: decrypt(row.encryptedKey) };
+        return { provider: p, apiKey: decrypt(row.encryptedKey), isByok: true };
       } catch {
         throw new ByokDecryptError(p);
       }