diff --git a/apps/api/src/auth/user.ts b/apps/api/src/auth/user.ts
index aacd2e1..2de9e42 100644
--- a/apps/api/src/auth/user.ts
+++ b/apps/api/src/auth/user.ts
@@ -156,6 +156,11 @@ export async function upsertUser(oidcIss: string, oidcSub: string, displayName?:
   const shouldBeAdmin = flagRow?.value !== 'true' && Number(count) === 0;
 
   // 5. Insert new user row
+  // claimed=true: an OIDC-created user is identity-bound at insert time and is
+  // never a pending wizard bootstrap user. Setting this explicitly prevents the
+  // TOCTOU guard in POST /credential (which counts WHERE oidc_iss IS NULL AND
+  // claimed = false) from ever treating a fresh OIDC insert as an unclaimed
+  // wizard row (WR-01).
   // mysql2 has no RETURNING clause — use $returningId() then re-select
   const [inserted] = await db
     .insert(users)
@@ -165,6 +170,7 @@ export async function upsertUser(oidcIss: string, oidcSub: string, displayName?:
       displayName: displayName ?? null,
       color,
       isAdmin: shouldBeAdmin,
+      claimed: true,
     })
     .$returningId();
 
diff --git a/apps/api/src/routes/setup.ts b/apps/api/src/routes/setup.ts
index 5d5ec8f..737c597 100644
--- a/apps/api/src/routes/setup.ts
+++ b/apps/api/src/routes/setup.ts
@@ -259,11 +259,15 @@ setupRouter.post('/credential', zValidator('json', credentialSchema, noEchoHook)
   let localUser: typeof users.$inferSelect | undefined;
   try {
     localUser = await db.transaction(async (tx) => {
-      // Serialise: at most one unclaimed admin row may exist (WR-02).
+      // Serialise: at most one unclaimed wizard bootstrap row may exist (WR-02).
+      // The filter is (oidc_iss IS NULL AND claimed = false) — the precise definition
+      // of a "pending wizard bootstrap user" — so that OIDC-created rows (which are
+      // born with claimed=true after WR-01 fix, but could theoretically be claimed=false
+      // on legacy data) are never counted here (WR-01 defense-in-depth).
       // Cast through unknown — Drizzle mysql2 execute() returns [rows, fields] for SELECTs;
       // the generic type parameter on execute() is not sufficient to type the result correctly.
       const countRows = (await tx.execute(
-        sql`SELECT COUNT(*) AS count FROM users WHERE claimed = false FOR UPDATE`,
+        sql`SELECT COUNT(*) AS count FROM users WHERE oidc_iss IS NULL AND claimed = false FOR UPDATE`,
       )) as unknown as [{ count: string | number }[], unknown];
       const unclaimedCount = Number(countRows[0][0]?.count ?? 0);
       if (unclaimedCount > 0) {
diff --git a/apps/api/tests/auth/user.test.ts b/apps/api/tests/auth/user.test.ts
index 627e63c..82ab413 100644
--- a/apps/api/tests/auth/user.test.ts
+++ b/apps/api/tests/auth/user.test.ts
@@ -441,6 +441,55 @@ describe('upsertUser', () => {
     // select must only have been called once (identity lookup, then early-return)
     expect(mockDb.select).toHaveBeenCalledTimes(1);
   });
+
+  // WR-01: upsertUser's fresh OIDC insert must set claimed=true.
+  // An OIDC-created user is identity-bound at insert time and must NOT be born
+  // with claimed=false, which would make it indistinguishable from a pending
+  // wizard bootstrap user (oidcIss IS NULL AND claimed=false) in the TOCTOU guard.
+  it('WR-01: fresh OIDC insert sets claimed=true (OIDC user is never a pending wizard user)', async () => {
+    const iss = 'https://auth.example.com';
+    const sub = 'sub-wr01-claimed';
+
+    let selectCallCount = 0;
+    mockDb.select.mockImplementation(() => {
+      selectCallCount++;
+      if (selectCallCount === 1) return makeSelectChain([]); // identity lookup — not found
+      if (selectCallCount === 2) return makeSelectChain([]); // setup_complete — not set
+      if (selectCallCount === 3) {
+        // Used-colors query
+        return { from: vi.fn().mockResolvedValue([]) };
+      }
+      if (selectCallCount === 4) {
+        // Admin COUNT
+        return makeSelectChain([{ count: 0 }]);
+      }
+      // Re-fetch after insert
+      return makeSelectChain([
+        {
+          id: 20,
+          oidcIss: iss,
+          oidcSub: sub,
+          displayName: null,
+          color: COLOR_PALETTE[0],
+          isAdmin: true,
+          claimed: true,
+          createdAt: new Date(),
+        },
+      ]);
+    });
+
+    mockDb.insert.mockReturnValue(makeInsertChain([{ id: 20 }]));
+
+    await upsertUser(iss, sub);
+
+    // The insert values must include claimed: true
+    const insertValues = mockDb.insert.mock.results[0]?.value?.values.mock.calls[0]?.[0];
+    expect(insertValues).toBeDefined();
+    expect(insertValues.claimed).toBe(true);
+    // And it must carry a real oidcIss (not null — distinguishable from wizard row)
+    expect(insertValues.oidcIss).toBe(iss);
+    expect(insertValues.oidcSub).toBe(sub);
+  });
 });
 
 // ── Plan 12-03: D-08 first-login-claims (Wave-2 GREEN — full test implementations) ──
diff --git a/apps/api/tests/routes/setup.test.ts b/apps/api/tests/routes/setup.test.ts
index ebe0fc5..0942c6e 100644
--- a/apps/api/tests/routes/setup.test.ts
+++ b/apps/api/tests/routes/setup.test.ts
@@ -478,6 +478,39 @@ describe('POST /api/setup/credential', () => {
     const body = JSON.parse(bodyText) as { error: string };
     expect(body.error).toBe('Invalid request');
   });
+
+  // WR-01: TOCTOU guard must ignore OIDC users that happen to have claimed=false
+  // (oidcIss IS NOT NULL). Only wizard bootstrap users (oidcIss IS NULL AND claimed=false)
+  // must trigger the DUPLICATE_UNCLAIMED guard. This prevents a partially-bootstrapped
+  // instance (where an OIDC user somehow exists pre-setup) from permanently blocking
+  // the wizard credential step with 409.
+  it('WR-01: TOCTOU guard ignores claimed=false OIDC users (oidcIss NOT NULL) — credential step still succeeds', async () => {
+    // Seed an OIDC user with claimed=false to simulate the latent bug scenario.
+    // After the WR-01 fix upsertUser always inserts claimed=true for OIDC users, but
+    // this tests that the guard's WHERE clause is narrowed correctly for defense-in-depth.
+    await db.insert(users).values({
+      oidcIss: 'https://auth.test.setup',
+      oidcSub: `sub-wr01-oidc-claimed-false-${Date.now()}`,
+      displayName: 'OIDC User With claimed=false',
+      color: '#4A90D9',
+      isAdmin: false,
+      claimed: false,  // legacy/hypothetical — oidcIss is NOT NULL
+    });
+
+    mockValidateCredentialShouldThrow = false;
+
+    const app = await getApp();
+    const res = await app.fetch(
+      jsonRequest('POST', '/api/setup/credential', {
+        fastmailEmail: 'operator@fastmail.com',
+        appPassword: 'valid-app-password-wr01',
+      }),
+    );
+    // Must succeed — the OIDC-with-oidcIss row must NOT block the wizard
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { ok: boolean };
+    expect(body.ok).toBe(true);
+  });
 });
 
 // ===========================================================================