diff --git a/src/main/codex-accounts/codex-account-identity-api-key-guard.test.ts b/src/main/codex-accounts/codex-account-identity-api-key-guard.test.ts
new file mode 100644
index 00000000000..c522b892ebc
--- /dev/null
+++ b/src/main/codex-accounts/codex-account-identity-api-key-guard.test.ts
@@ -0,0 +1,89 @@
+import { mkdtempSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { describe, expect, it } from 'vitest'
+import { CodexAccountIdentity } from './codex-account-identity'
+import { readCodexAuthIdentity } from './codex-auth-identity'
+
+/** Encodes a JWT whose payload carries the given claims; only the payload segment is read. */
+function idTokenWithClaims(claims: Record<string, unknown>): string {
+  const payload = Buffer.from(JSON.stringify(claims), 'utf-8').toString('base64url')
+  return `header.${payload}.signature`
+}
+
+function homeWithAuthJson(auth: Record<string, unknown>): string {
+  const home = mkdtempSync(join(tmpdir(), 'codex-identity-'))
+  writeFileSync(join(home, 'auth.json'), JSON.stringify(auth), 'utf-8')
+  return home
+}
+
+describe('managed-home Codex identity', () => {
+  const identity = new CodexAccountIdentity((candidatePath) => candidatePath)
+
+  it('resolves no identity for an API-key login that still holds a stale tokens blob', () => {
+    // Why: the stale OAuth email is not who this credential authenticates as, and it is
+    // the claim used to prove a shared-home auth.json belongs to the selected account.
+    const home = homeWithAuthJson({
+      OPENAI_API_KEY: 'sk-test',
+      tokens: {
+        account_id: 'stale-account',
+        id_token: idTokenWithClaims({ email: 'stale@example.com' })
+      }
+    })
+
+    expect(identity.readFromHome(home, 'account-1')).toEqual({
+      email: null,
+      providerAccountId: null,
+      workspaceLabel: null,
+      workspaceAccountId: null
+    })
+  })
+
+  it('still resolves an OAuth identity when no API key is declared', () => {
+    const home = homeWithAuthJson({
+      tokens: {
+        account_id: 'real-account',
+        id_token: idTokenWithClaims({ email: 'real@example.com' })
+      }
+    })
+
+    expect(identity.readFromHome(home, 'account-1')).toMatchObject({
+      email: 'real@example.com',
+      providerAccountId: 'real-account'
+    })
+  })
+})
+
+describe('readCodexAuthIdentity account-id fallback', () => {
+  it('falls through to the auth claim for providerAccountId when tokens.account_id is blank', () => {
+    // Why: a blank token field must not end the fallback chain — an empty string is not nullish.
+    const contents = JSON.stringify({
+      tokens: {
+        account_id: '   ',
+        id_token: idTokenWithClaims({
+          'https://api.openai.com/auth': { chatgpt_account_id: 'claim-account' }
+        })
+      }
+    })
+
+    expect(readCodexAuthIdentity(contents)).toMatchObject({
+      providerAccountId: 'claim-account',
+      // workspaceAccountId's chain skips the auth claim and ends at the top-level one.
+      workspaceAccountId: null
+    })
+  })
+
+  it('falls through to the top-level claim for workspaceAccountId when tokens.account_id is blank', () => {
+    const contents = JSON.stringify({
+      tokens: {
+        account_id: '',
+        id_token: idTokenWithClaims({ chatgpt_account_id: 'top-level-account' })
+      }
+    })
+
+    expect(readCodexAuthIdentity(contents)).toMatchObject({
+      providerAccountId: 'top-level-account',
+      workspaceAccountId: 'top-level-account'
+    })
+  })
+})
diff --git a/src/main/codex-accounts/codex-account-identity.ts b/src/main/codex-accounts/codex-account-identity.ts
index 78e465d94dc..30b42743ef7 100644
--- a/src/main/codex-accounts/codex-account-identity.ts
+++ b/src/main/codex-accounts/codex-account-identity.ts
@@ -8,6 +8,15 @@ import { ManagedCodexHomeTemporarilyUnavailableError } from './host-codex-manage
 
 export type ResolvedCodexIdentity = CodexAuthIdentity
 
+/** API-key logins carry no OAuth identity even when a stale `tokens` blob is still present. */
+function declaresApiKeyCredential(parsed: unknown): boolean {
+  if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
+    return false
+  }
+  const apiKey = (parsed as Record<string, unknown>).OPENAI_API_KEY
+  return typeof apiKey === 'string' && apiKey.trim() !== ''
+}
+
 export class CodexAccountIdentity {
   constructor(
     private readonly assertManagedHomePath: (
@@ -33,8 +42,9 @@ export class CodexAccountIdentity {
       }
       throw new ManagedCodexHomeTemporarilyUnavailableError(undefined, { cause: error })
     }
+    let parsed: unknown
     try {
-      JSON.parse(contents)
+      parsed = JSON.parse(contents)
     } catch {
       // Why: a raw SyntaxError echoes credential bytes into logs/error UI; a
       // corrupt auth.json must fail loudly but without them (same sanitization
@@ -45,6 +55,14 @@ export class CodexAccountIdentity {
     // claims. Returning nulls causes the caller to fail with a clear
     // "could not resolve the account email" error rather than crashing
     // on missing nested token fields.
+    if (declaresApiKeyCredential(parsed)) {
+      return {
+        email: null,
+        providerAccountId: null,
+        workspaceLabel: null,
+        workspaceAccountId: null
+      }
+    }
     const identity = readCodexAuthIdentity(contents)
     if (!identity) {
       return {
@@ -96,8 +114,7 @@ export class CodexAccountIdentity {
       console.warn('[codex-accounts] System-default Codex auth has an unexpected format')
       return this.systemDefaultIdentity(true, 'none')
     }
-    const raw = parsed as Record<string, unknown>
-    if (typeof raw.OPENAI_API_KEY === 'string' && raw.OPENAI_API_KEY.trim() !== '') {
+    if (declaresApiKeyCredential(parsed)) {
       // Why: API-key/custom-provider logins carry no OAuth identity or ChatGPT
       // usage. Surface them as a custom provider, not a blank/broken row.
       return this.systemDefaultIdentity(true, 'api-key')
diff --git a/src/main/codex-accounts/codex-auth-identity.ts b/src/main/codex-accounts/codex-auth-identity.ts
index 06303c22112..0455b5e481f 100644
--- a/src/main/codex-accounts/codex-auth-identity.ts
+++ b/src/main/codex-accounts/codex-auth-identity.ts
@@ -167,14 +167,18 @@ export function readCodexAuthIdentity(contents: string): CodexAuthIdentity | nul
   const payload = idToken ? parseJwtPayload(idToken) : null
   const authClaims = readRecordClaim(payload, 'https://api.openai.com/auth')
   const profileClaims = readRecordClaim(payload, 'https://api.openai.com/profile')
+  // Why: normalize before the fallback chains, not after — a blank tokens.account_id
+  // must fall through to the JWT claims rather than ending the chain on an empty string.
+  const tokenAccountId = normalizeField(
+    readStringClaim(tokens, 'account_id') ?? readStringClaim(tokens, 'accountId')
+  )
 
   return {
     email: normalizeField(
       readStringClaim(payload, 'email') ?? readStringClaim(profileClaims, 'email')
     ),
     providerAccountId: normalizeField(
-      readStringClaim(tokens, 'account_id') ??
-        readStringClaim(tokens, 'accountId') ??
+      tokenAccountId ??
         readStringClaim(authClaims, 'chatgpt_account_id') ??
         readStringClaim(payload, 'chatgpt_account_id')
     ),
@@ -184,8 +188,7 @@ export function readCodexAuthIdentity(contents: string): CodexAuthIdentity | nul
     ),
     workspaceAccountId: normalizeField(
       readStringClaim(authClaims, 'workspace_account_id') ??
-        readStringClaim(tokens, 'account_id') ??
-        readStringClaim(tokens, 'accountId') ??
+        tokenAccountId ??
         readStringClaim(payload, 'chatgpt_account_id')
     )
   }