Index: src/routes/admin-paid.js
===================================================================
--- src/routes/admin-paid.js	(revision b9beb16195c00e4ddc58955e530ea843e4be938f)
+++ src/routes/admin-paid.js	(revision 4590e66b7458ade434bf5a870980abc09155b777)
@@ -48,5 +48,5 @@
 router.post('/', requireGod, (req, res) => {
   if (!gate(req, res)) return;
-  if (!cryptoBoxReady()) return res.redirect('/admin/paid?error=' + encodeURIComponent('PAID_SECRET ontbreekt in de serverconfig; secrets kunnen niet versleuteld worden opgeslagen.'));
+  if (!cryptoBoxReady()) return res.redirect('/admin/paid?error=' + encodeURIComponent('De encryptiesleutel kon niet worden aangemaakt of gelezen (schrijfrechten op de opslagmap?); secrets kunnen niet veilig worden opgeslagen.'));
   const b = req.body || {};
   const eur = String(b.default_min_eur || '').replace(',', '.').trim();
Index: src/services/CryptoBox.js
===================================================================
--- src/services/CryptoBox.js	(revision b9beb16195c00e4ddc58955e530ea843e4be938f)
+++ src/services/CryptoBox.js	(revision 4590e66b7458ade434bf5a870980abc09155b777)
@@ -1,20 +1,56 @@
 // Symmetric encryption for secrets at rest (paid posts: the site owner's
 // Patreon creator token, klonkt-demo-aki slice 1). AES-256-GCM with a key
-// derived from PAID_SECRET (env), so a database dump alone leaks nothing usable.
+// derived from a secret, so a database dump alone leaks nothing usable.
 // Format: base64(iv) : base64(tag) : base64(ciphertext).
 //
-// The codebase had no symmetric-crypto helper; this is that one, kept tiny and
-// native (no dependency). If PAID_SECRET is unset, encryption is refused loudly
-// rather than storing plaintext.
+// The secret is resolved in this order so nobody has to edit the env:
+//   1. PAID_SECRET (env) — authoritative; a self-hoster who set it by hand
+//      (or Bart, who already did) keeps working unchanged.
+//   2. a persisted key file next to the database, auto-generated on first use
+//      (0600). This is what "first run" and "existing users after an update"
+//      get automatically.
+// The key lives OUTSIDE the sqlite DB on purpose: encrypting the Patreon
+// secrets is pointless if the key sits in the same file a DB dump would leak.
 import crypto from 'crypto';
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+// The key file sits in the same directory as the database.
+function keyFilePath() {
+  const dbPath = process.env.DATABASE_PATH || path.join(__dirname, '../../storage/database.sqlite');
+  const dir = dbPath === ':memory:' ? path.join(__dirname, '../../storage') : path.dirname(dbPath);
+  return path.join(dir, '.paid-secret');
+}
+
+// Read the persisted key, generating + writing it (0600) the first time.
+function fileSecret() {
+  const file = keyFilePath();
+  try {
+    const existing = fs.readFileSync(file, 'utf8').trim();
+    if (existing.length >= 16) return existing;
+  } catch { /* not created yet */ }
+  const generated = crypto.randomBytes(32).toString('base64');
+  fs.mkdirSync(path.dirname(file), { recursive: true });
+  fs.writeFileSync(file, generated, { mode: 0o600 });
+  try { fs.chmodSync(file, 0o600); } catch { /* non-POSIX fs */ }
+  return generated;
+}
+
+// env wins; otherwise the auto-generated file. Never returns an ephemeral key:
+// if the file can't be persisted, fileSecret throws and the feature stays gated
+// (cryptoBoxReady false) rather than encrypting with a key lost on restart.
+function resolveSecret() {
+  const env = process.env.PAID_SECRET;
+  if (env && String(env).length >= 16) return String(env);
+  return fileSecret();
+}
 
 let _key = null;
 function key() {
   if (_key) return _key;
-  const secret = process.env.PAID_SECRET;
-  if (!secret || String(secret).length < 16) {
-    throw new Error('PAID_SECRET is missing or too short (need >= 16 chars) to encrypt paid-posts secrets');
-  }
-  _key = crypto.scryptSync(String(secret), 'klonkt-paid', 32);
+  _key = crypto.scryptSync(resolveSecret(), 'klonkt-paid', 32);
   return _key;
 }
Index: src/services/PaidPatreonService.js
===================================================================
--- src/services/PaidPatreonService.js	(revision b9beb16195c00e4ddc58955e530ea843e4be938f)
+++ src/services/PaidPatreonService.js	(revision 4590e66b7458ade434bf5a870980abc09155b777)
@@ -50,5 +50,5 @@
 // the admin form can be re-saved without re-pasting the secret.
 export function saveOwnerConfig(siteId, patch) {
-  if (!cryptoBoxReady()) throw new Error('PAID_SECRET is not set: cannot store Patreon secrets');
+  if (!cryptoBoxReady()) throw new Error('encryption key unavailable: cannot store Patreon secrets');
   const cur = getOwnerConfig(siteId) || {};
   const merged = {
Index: src/views/pages/admin-paid.ejs
===================================================================
--- src/views/pages/admin-paid.ejs	(revision b9beb16195c00e4ddc58955e530ea843e4be938f)
+++ src/views/pages/admin-paid.ejs	(revision 4590e66b7458ade434bf5a870980abc09155b777)
@@ -10,5 +10,5 @@
   <% if (error) { %><p style="color:#c0392b"><%= error %></p><% } %>
   <% if (!secretReady) { %>
-    <p style="color:#c0392b">Let op: <code>PAID_SECRET</code> staat niet in de serverconfig. Zonder die sleutel kunnen secrets niet versleuteld worden opgeslagen.</p>
+    <p style="color:#c0392b">Let op: de encryptiesleutel kon niet worden aangemaakt of gelezen (schrijfrechten op de opslagmap?). Zonder sleutel kunnen secrets niet veilig worden opgeslagen.</p>
   <% } %>