[glm-grade=A] fix(config): teach schema KNOWN_KEYS the licenseBackup/_version writer keys (DC-091)

Every startup logged two false-positive 'Unknown config key — possible typo?'
warns: licenseBackup (written by src/managers/license-manager.js:510 activation
persistence) and _version (stamped by src/config/migrations.js). Both are
first-party writers the validator was never taught about (DC-091).

- config-schema.js: add both keys to KNOWN_KEYS with a source-of-writes comment
- config-schema.test.js (new): 5 regression tests — live production config keyset
  validates with zero unknown-key warnings, writer keys never warn, genuine
  typos still warn (exact string), license/licenseBackup sync guard, _version
  recognized at every migration value

Verified: full jest suite 111 suites / 2621 tests green (baseline 110/2616).
Warns reproduced in live container logs 2026-08-22T23:53:54Z; live config.json
contains both keys (licenseBackup activation, _version 2).

Judge: GLM-5.3 cold read via delegate_task (deleg_30e52384, 36s) — grade A, ship.
Verdict URN: urn:ump:ermkvz6ifbp5svga5cnapv5jhm7c5b7qdbwjjerfpxbwcrolm2za (readback verified)
Codex quota-walled until 2026-08-29; GLM stand-in per Sami 2026-08-17 directive.

dashcaddy-api/__tests__/config-schema.test.js

@@ -0,0 +1,72 @@
+'use strict';
+
+/**
+ * Regression tests for config-schema.js KNOWN_KEYS — DC-091.
+ *
+ * Bug: license-manager.js persists config.licenseBackup (activation
+ * restore-on-restart) and src/config/migrations.js stamps config._version,
+ * but neither key was in KNOWN_KEYS — so every startup logged
+ * `Unknown config key "licenseBackup" / "_version" — possible typo?`
+ * false positives (verified in live dashcaddy-api container logs,
+ * 2026-08-22T23:53:54Z restart).
+ *
+ * These tests pin: (1) the live production config key set validates with
+ * zero unknown-key warnings, (2) genuine typos still warn, (3) the schema
+ * stays in sync with the first-party writer keys.
+ */
+
+const { validateConfig } = require('../src/utilities/config-schema');
+
+describe('config-schema KNOWN_KEYS vs first-party writers (DC-091)', () => {
+  // Exact key set of the live production config.json (DNS2, verified
+  // 2026-08-23). If a new key appears here, teach KNOWN_KEYS about it —
+  // or fix the writer if it's a typo.
+  const LIVE_CONFIG_KEYS = [
+    '_version', 'configurationType', 'customFavicon', 'customLogo',
+    'dashboardHost', 'dashboardTitle', 'dns', 'dnsServers', 'language',
+    'license', 'licenseBackup', 'logoPosition', 'pylon', 'setupComplete',
+    'timestamp', 'tld', 'updatedAt'
+  ];
+
+  test('live production config key set produces zero unknown-key warnings', () => {
+    const config = {};
+    for (const key of LIVE_CONFIG_KEYS) {
+      // Minimal valid-ish values; validateConfig only cares about shape
+      // for these keys, and unknown-key detection is the target here.
+      config[key] = key === '_version' ? 2 : (key === 'dnsServers' ? {} : 'x');
+    }
+    const result = validateConfig(config);
+    const unknownWarnings = result.warnings.filter((w) => w.includes('Unknown config key'));
+    expect(unknownWarnings).toEqual([]);
+  });
+
+  test('licenseBackup and _version (first-party writer keys) do not warn', () => {
+    const result = validateConfig({ licenseBackup: { code: 'DC-...' }, _version: 2 });
+    expect(result.warnings).toEqual([]);
+  });
+
+  test('genuine typos still warn (guard against over-allowing)', () => {
+    const result = validateConfig({ dashboadTitle: 'typo' });
+    expect(result.warnings).toEqual([
+      'Unknown config key "dashboadTitle" — possible typo?'
+    ]);
+  });
+
+  test('KNOWN_KEYS stays in sync with license-manager writer keys', () => {
+    // license-manager writes config.licenseBackup and config.license — both
+    // must be recognized. We assert via validateConfig (public surface)
+    // rather than importing the private KNOWN_KEYS array.
+    const result = validateConfig({ license: { code: 'DC-...' }, licenseBackup: { code: 'DC-...' } });
+    expect(result.warnings.filter((w) => w.includes('Unknown config key'))).toEqual([]);
+  });
+});
+
+describe('config-schema sync guard: migrations writer', () => {
+  test('_version is recognized at every migration version value', () => {
+    // migrations.js bumps _version 0→1→2; the key itself must never warn.
+    for (const v of [0, 1, 2, 99]) {
+      const result = validateConfig({ _version: v });
+      expect(result.warnings).toEqual([]);
+    }
+  });
+});

dashcaddy-api/src/utilities/config-schema.js

@@ -14,7 +14,11 @@ const KNOWN_KEYS = [
   'configurationType', 'defaults', 'customLogo', 'customFavicon',
   'dashboardTitle', 'tailscale', 'license', 'skipped',
   'routingMode', 'domain', 'email', 'defaultIP', 'pylon',
-  'customLogoDark', 'customLogoLight', 'language'
+  'customLogoDark', 'customLogoLight', 'language',
+  // license-manager.js persists the last activation to config.licenseBackup
+  // (restore-on-restart path); src/config/migrations.js stamps _version.
+  // Both are first-party writes — see DC-091.
+  'licenseBackup', '_version'
 ];
 
 /**