diff --git a/apps/api/src/lib/setupGuard.ts b/apps/api/src/lib/setupGuard.ts
index b7ac3d4..9f24fb1 100644
--- a/apps/api/src/lib/setupGuard.ts
+++ b/apps/api/src/lib/setupGuard.ts
@@ -11,20 +11,33 @@
  * event-loop tick. The per-call freshness pattern mirrors db.select() in health.ts.
  *
  * Two-branch lock logic (D-10):
- *   1. Explicit: app_config.setup_complete === 'true'
+ *   1. Explicit: app_config.setup_complete === 'true'  (unconditional — lock once written)
  *   2. Effective: a member_credentials row exists AND VAPID_PRIVATE_KEY + VAPID_PUBLIC_KEY env set
+ *      EXCEPT when an unclaimed local wizard user exists (oidcIss IS NULL, claimed=false),
+ *      which means the wizard is still in-progress and /complete has not yet run.
  *
  * Real implementation (Plan 02): reads app_config.setup_complete + checks
  * member_credentials + VAPID env (effective-config branch, D-10).
+ *
+ * CR-01 fix: the effective-config branch must not fire while the wizard is in-progress.
+ * After POST /credential writes a member_credentials row but before POST /complete writes
+ * setup_complete, any production container with VAPID env set would have the effective-config
+ * branch return true, permanently blocking /complete. The unclaimed-user sentinel prevents this:
+ *   - During wizard (credential written, /complete not yet called): unclaimed user exists → false
+ *   - After /complete: setup_complete='true' → Check 1 locks (unconditional)
+ *   - Post-setup first OIDC login: first-login-claims sets claimed=true → no unclaimed user →
+ *     effective-config branch fires correctly for legacy-recovery (no setup_complete key) instances
+ *   - Env-only configured instance (no wizard): no wizard-created unclaimed user →
+ *     effective-config lock fires as expected
  */
 
 import { db } from '../db/client.js';
-import { appConfig, memberCredentials } from '../db/schema.js';
-import { eq } from 'drizzle-orm';
+import { appConfig, memberCredentials, users } from '../db/schema.js';
+import { eq, isNull, and } from 'drizzle-orm';
 
 /** Returns true if the wizard is already locked. Re-evaluated fresh — NEVER cache at module level. */
 export async function isSetupLocked(): Promise<boolean> {
-  // Check 1: explicit setup_complete flag in app_config
+  // Check 1: explicit setup_complete flag in app_config (unconditional — always locks once written)
   const [flagRow] = await db
     .select({ value: appConfig.value })
     .from(appConfig)
@@ -32,7 +45,18 @@ export async function isSetupLocked(): Promise<boolean> {
     .limit(1);
   if (flagRow?.value === 'true') return true;
 
-  // Check 2: effective configuration — member_credentials row exists AND VAPID env set (D-10)
+  // Check 2: effective-config (legacy recovery for pre-Phase-12 instances that have no
+  // setup_complete key but are fully configured). Only applies when the wizard is NOT
+  // in-progress. An unclaimed local user (oidcIss IS NULL, claimed=false) is the definitive
+  // "wizard still in-progress" signal: /credential creates it before /complete is called,
+  // and first-login-claims sets claimed=true after the first OIDC login post-setup.
+  const [unclaimedRow] = await db
+    .select({ id: users.id })
+    .from(users)
+    .where(and(isNull(users.oidcIss), eq(users.claimed, false)))
+    .limit(1);
+  if (unclaimedRow) return false; // wizard in-progress — never effective-lock
+
   const [credRow] = await db.select({ id: memberCredentials.id }).from(memberCredentials).limit(1);
   const vapidPresent = !!process.env.VAPID_PRIVATE_KEY && !!process.env.VAPID_PUBLIC_KEY;
   return !!credRow && vapidPresent;
diff --git a/apps/api/tests/routes/setup.test.ts b/apps/api/tests/routes/setup.test.ts
index bce06f1..ebe0fc5 100644
--- a/apps/api/tests/routes/setup.test.ts
+++ b/apps/api/tests/routes/setup.test.ts
@@ -306,6 +306,21 @@ describe('POST /api/setup/config', () => {
     );
     expect(res.status).toBe(400);
   });
+
+  // IN-01: appExternalUrl must also require https:// — it is injected as OIDC_AUTH_EXTERNAL_URL
+  // (the redirect URI base) and Authelia rejects non-https redirect URIs in production.
+  it('IN-01: returns 400 when appExternalUrl is an http:// URL (must require https)', async () => {
+    const app = await getApp();
+    const res = await app.fetch(
+      jsonRequest('POST', '/api/setup/config', {
+        oidcIssuer: 'https://auth.example.com',
+        oidcClientId: 'familysync-client',
+        vapidPublicKey: VAPID_PUBLIC_KEY,
+        appExternalUrl: 'http://insecure-app.example.com',
+      }),
+    );
+    expect(res.status).toBe(400);
+  });
 });
 
 // ===========================================================================
@@ -554,4 +569,41 @@ describe('/api/setup/* — 423 when effectively configured (D-10 effective-confi
     // Not locked — no credentials means effective-config condition is false
     expect(res.status).not.toBe(423);
   });
+
+  // CR-01 regression: reproduces the production lock-out scenario.
+  // With VAPID env PRESENT, after /credential creates an unclaimed user + credential row,
+  // POST /complete must still succeed (200, writes setup_complete). Only AFTER /complete
+  // runs does isSetupLocked() return true (via Check 1 / explicit flag) — so a second
+  // /complete call returns 423.
+  //
+  // The bug was that the effective-config branch (credRow + vapidPresent) fired during
+  // the credential→complete window, blocking /complete with 423 permanently.
+  // beforeEach masks this by clearing VAPID env — so we set it explicitly here.
+  it('CR-01: /complete succeeds when VAPID env is set AND unclaimed wizard user+credential exist (in-progress wizard)', async () => {
+    // Explicitly set VAPID env (do NOT rely on beforeEach clearing it)
+    process.env.VAPID_PRIVATE_KEY = VAPID_PRIVATE_KEY;
+    process.env.VAPID_PUBLIC_KEY = VAPID_PUBLIC_KEY;
+
+    // Simulate POST /credential: creates unclaimed local user + credential (wizard in-progress)
+    const userId = await seedLocalUser('cr01-regression');
+    await seedCredential(userId);
+
+    const app = await getApp();
+
+    // /complete must succeed (200) — effective-config lock must NOT fire while wizard in-progress
+    const completeRes = await app.fetch(jsonRequest('POST', '/api/setup/complete'));
+    expect(completeRes.status).toBe(200);
+
+    // Verify setup_complete was written to app_config
+    const [flagRow] = await db
+      .select({ value: appConfig.value })
+      .from(appConfig)
+      .where(eq(appConfig.key, 'setup_complete'))
+      .limit(1);
+    expect(flagRow?.value).toBe('true');
+
+    // Second /complete must return 423 — explicit setup_complete flag now locks unconditionally
+    const secondRes = await app.fetch(jsonRequest('POST', '/api/setup/complete'));
+    expect(secondRes.status).toBe(423);
+  });
 });