diff --git a/apps/api/src/auth/user.ts b/apps/api/src/auth/user.ts
index 3e3a383..aacd2e1 100644
--- a/apps/api/src/auth/user.ts
+++ b/apps/api/src/auth/user.ts
@@ -8,9 +8,9 @@
  * Source: RESEARCH.md § "User upsert with color assignment"
  */
 
-import { and, eq, sql } from 'drizzle-orm';
+import { and, eq, isNull, sql } from 'drizzle-orm';
 import { db } from '../db/client.js';
-import { users } from '../db/schema.js';
+import { users, appConfig } from '../db/schema.js';
 
 /**
  * Accessible, visually-distinct palette for per-member member-color assignment.
@@ -96,7 +96,42 @@ export async function upsertUser(oidcIss: string, oidcSub: string, displayName?:
     return existing[0];
   }
 
-  // 2. Assign the first palette color NOT already in use by another member.
+  // 2. Check app_config.setup_complete and attempt first-login-claims (D-08).
+  //    When setup is complete, the first OIDC login from an unknown identity claims
+  //    the single unclaimed local user (oidcIss IS NULL AND claimed=false), binding
+  //    the OIDC identity to the wizard-provisioned row. This preserves is_admin and
+  //    the CalDAV credential stored by the wizard.
+  //    MUST NOT match by email — query is strictly isNull(oidcIss) AND claimed=false (D-10).
+  const [flagRow] = await db
+    .select({ value: appConfig.value })
+    .from(appConfig)
+    .where(eq(appConfig.key, 'setup_complete'))
+    .limit(1);
+
+  if (flagRow?.value === 'true') {
+    const [unclaimed] = await db
+      .select()
+      .from(users)
+      .where(and(isNull(users.oidcIss), eq(users.claimed, false)))
+      .limit(1);
+
+    if (unclaimed) {
+      // Claim: bind the OIDC identity, mark claimed=true, update displayName if provided.
+      // is_admin is NOT overwritten — it was pre-set by the wizard (operator's intent).
+      await db
+        .update(users)
+        .set({
+          oidcIss,
+          oidcSub,
+          claimed: true,
+          displayName: displayName ?? unclaimed.displayName,
+        })
+        .where(eq(users.id, unclaimed.id));
+      return { ...unclaimed, oidcIss, oidcSub, claimed: true };
+    }
+  }
+
+  // 3. Assign the first palette color NOT already in use by another member.
   //    A plain COUNT(*) % palette collides under deletions: a deleted user
   //    shifts the count so the next insert reuses an in-use slot (observed in
   //    Gate 2 — two members both got #E8734A). Selecting the first unused color
@@ -109,20 +144,18 @@ export async function upsertUser(oidcIss: string, oidcSub: string, displayName?:
     COLOR_PALETTE.find((c) => !usedColors.has(c)) ??
     COLOR_PALETTE[usedColors.size % COLOR_PALETTE.length];
 
-  // 3. First-login-wins is_admin bootstrap (D-01).
-  //    When zero admins currently exist, the first new user becomes admin.
-  //    Phase 12 will tighten this to: first user after app_config.setup_complete.
-  //    Until then, "first user when zero admins exist" is the bootstrap condition.
-  //    This hook reads cleanly: Phase 12 adds a setup_complete check before the
-  //    COUNT, so only first login AFTER setup is flagged — no restructuring needed.
+  // 4. First-login-wins is_admin bootstrap (D-01), tightened by Phase 12 (D-08).
+  //    When setup_complete is true, a claimed admin already exists — new users must
+  //    NOT auto-promote. Only grant admin when setup is not yet complete AND no admins
+  //    exist (the original first-login-wins bootstrap for fresh pre-wizard instances).
   const [{ count }] = await db
     .select({ count: sql<number>`COUNT(*)` })
     .from(users)
     .where(eq(users.isAdmin, true))
     .limit(1);
-  const shouldBeAdmin = Number(count) === 0;
+  const shouldBeAdmin = flagRow?.value !== 'true' && Number(count) === 0;
 
-  // 4. Insert new user row
+  // 5. Insert new user row
   // mysql2 has no RETURNING clause — use $returningId() then re-select
   const [inserted] = await db
     .insert(users)
@@ -135,7 +168,7 @@ export async function upsertUser(oidcIss: string, oidcSub: string, displayName?:
     })
     .$returningId();
 
-  // 5. Re-select to return the full typed row
+  // 6. Re-select to return the full typed row
   const [newUser] = await db.select().from(users).where(eq(users.id, inserted.id)).limit(1);
 
   return newUser;