diff --git a/src/utils/providerValidation.test.ts b/src/utils/providerValidation.test.ts
index 3917638f..d88fef77 100644
--- a/src/utils/providerValidation.test.ts
+++ b/src/utils/providerValidation.test.ts
@@ -3,6 +3,9 @@ import { afterEach, expect, test } from 'bun:test'
 import { getProviderValidationError } from './providerValidation.ts'
 
 const originalEnv = {
+  CLAUDE_CODE_USE_OPENAI: process.env.CLAUDE_CODE_USE_OPENAI,
+  OPENAI_API_KEY: process.env.OPENAI_API_KEY,
+  OPENAI_BASE_URL: process.env.OPENAI_BASE_URL,
   CLAUDE_CODE_USE_GEMINI: process.env.CLAUDE_CODE_USE_GEMINI,
   GEMINI_API_KEY: process.env.GEMINI_API_KEY,
   GOOGLE_API_KEY: process.env.GOOGLE_API_KEY,
@@ -20,6 +23,9 @@ function restoreEnv(key: string, value: string | undefined): void {
 }
 
 afterEach(() => {
+  restoreEnv('CLAUDE_CODE_USE_OPENAI', originalEnv.CLAUDE_CODE_USE_OPENAI)
+  restoreEnv('OPENAI_API_KEY', originalEnv.OPENAI_API_KEY)
+  restoreEnv('OPENAI_BASE_URL', originalEnv.OPENAI_BASE_URL)
   restoreEnv('CLAUDE_CODE_USE_GEMINI', originalEnv.CLAUDE_CODE_USE_GEMINI)
   restoreEnv('GEMINI_API_KEY', originalEnv.GEMINI_API_KEY)
   restoreEnv('GOOGLE_API_KEY', originalEnv.GOOGLE_API_KEY)
@@ -71,3 +77,19 @@ test('still errors when no Gemini credential source is available', async () => {
     'GEMINI_API_KEY, GOOGLE_API_KEY, GEMINI_ACCESS_TOKEN, or Google ADC credentials are required when CLAUDE_CODE_USE_GEMINI=1.',
   )
 })
+
+test('openai missing key error includes recovery guidance and config locations', async () => {
+  process.env.CLAUDE_CODE_USE_OPENAI = '1'
+  process.env.OPENAI_BASE_URL = 'https://api.openai.com/v1'
+  delete process.env.OPENAI_API_KEY
+
+  const message = await getProviderValidationError(process.env)
+  expect(message).toContain(
+    'OPENAI_API_KEY is required when CLAUDE_CODE_USE_OPENAI=1 and OPENAI_BASE_URL is not local.',
+  )
+  expect(message).toContain(
+    'set CLAUDE_CODE_USE_OPENAI=0 in your shell environment',
+  )
+  expect(message).toContain('Saved startup settings can come from')
+  expect(message).toContain('.openclaude-profile.json')
+})
diff --git a/src/utils/providerValidation.ts b/src/utils/providerValidation.ts
index d1e3d353..5f462c35 100644
--- a/src/utils/providerValidation.ts
+++ b/src/utils/providerValidation.ts
@@ -1,14 +1,16 @@
+import { resolve } from 'node:path'
 import {
   getGithubEndpointType,
   isLocalProviderUrl,
   resolveCodexApiCredentials,
   resolveProviderRequest,
 } from '../services/api/providerConfig.js'
+import { getGlobalClaudeFile } from './env.js'
 import {
   type GeminiResolvedCredential,
   resolveGeminiCredential,
 } from './geminiAuth.js'
-import { redactSecretValueForDisplay } from './providerProfile.js'
+import { PROFILE_FILE_NAME, redactSecretValueForDisplay } from './providerProfile.js'
 
 function isEnvTruthy(value: string | undefined): boolean {
   if (!value) return false
@@ -61,6 +63,17 @@ function checkGithubTokenStatus(
   return 'valid'
 }
 
+function getOpenAIMissingKeyMessage(): string {
+  const globalConfigPath = getGlobalClaudeFile()
+  const profilePath = resolve(process.cwd(), PROFILE_FILE_NAME)
+
+  return [
+    'OPENAI_API_KEY is required when CLAUDE_CODE_USE_OPENAI=1 and OPENAI_BASE_URL is not local.',
+    `To recover, run /provider and switch provider, or set CLAUDE_CODE_USE_OPENAI=0 in your shell environment.`,
+    `Saved startup settings can come from ${globalConfigPath} or ${profilePath}.`,
+  ].join('\n')
+}
+
 export async function getProviderValidationError(
   env: NodeJS.ProcessEnv = process.env,
   options?: {
@@ -137,7 +150,7 @@ export async function getProviderValidationError(
     if (useGithub && hasGithubToken) {
       return null
     }
-    return 'OPENAI_API_KEY is required when CLAUDE_CODE_USE_OPENAI=1 and OPENAI_BASE_URL is not local.'
+    return getOpenAIMissingKeyMessage()
   }
 
   return null