diff --git a/src/services/api/client.ts b/src/services/api/client.ts
index 0d437105..b26e8b3f 100644
--- a/src/services/api/client.ts
+++ b/src/services/api/client.ts
@@ -27,6 +27,7 @@ import {
   OPENAI_OAUTH_DUMMY_KEY,
   shouldUseOpenAICodexAuth,
 } from '../openaiAuth/fetch.js'
+import { isOpenAIResponsesModel } from '../openaiAuth/models.js'
 import { isDebugToStdErr, logForDebugging } from '../../utils/debug.js'
 import {
   getAWSRegion,
@@ -137,11 +138,13 @@ export async function getAnthropicClient({
   await checkAndRefreshOAuthTokenIfNeeded()
   logForDebugging('[API:auth] OAuth token check complete')
 
+  const isOpenAIModel = model ? isOpenAIResponsesModel(model) : false
   const usingOpenAICodex =
     shouldUseOpenAICodexAuth() &&
     !isClaudeAISubscriber() &&
-    !process.env.ANTHROPIC_AUTH_TOKEN &&
-    !(apiKey || getAnthropicApiKey())
+    (isOpenAIModel ||
+      (!process.env.ANTHROPIC_AUTH_TOKEN &&
+        !(apiKey || getAnthropicApiKey())))
 
   if (!isClaudeAISubscriber() && !usingOpenAICodex) {
     await configureApiKeyHeaders(defaultHeaders, getIsNonInteractiveSession())
diff --git a/src/services/openaiAuth/models.ts b/src/services/openaiAuth/models.ts
index ca34e252..8eb0b4cb 100644
--- a/src/services/openaiAuth/models.ts
+++ b/src/services/openaiAuth/models.ts
@@ -22,6 +22,12 @@ export const OPENAI_CODEX_MODEL_CATALOG: OpenAIModelCatalogEntry[] = [
     description: 'Strong general-purpose model',
     descriptionForModel: 'GPT-5.4 - strong general-purpose model',
   },
+  {
+    value: 'gpt-5.5',
+    label: 'GPT-5.5',
+    description: 'Latest general-purpose model',
+    descriptionForModel: 'GPT-5.5 - latest general-purpose model',
+  },
   {
     value: OPENAI_DEFAULT_HAIKU_MODEL,
     label: 'GPT-5.4 Mini',
@@ -72,6 +78,8 @@ export function getOpenAIModelDisplayName(model: string): string | null {
   switch (model.trim().toLowerCase()) {
     case 'gpt-5.3-codex':
       return 'GPT-5.3 Codex'
+    case 'gpt-5.5':
+      return 'GPT-5.5'
     case 'gpt-5.4':
       return 'GPT-5.4'
     case 'gpt-5.4-mini':