diff --git a/packages/core/src/plugin/provider/openai.ts b/packages/core/src/plugin/provider/openai.ts
index 72cd1bc438c..6227f5ec278 100644
--- a/packages/core/src/plugin/provider/openai.ts
+++ b/packages/core/src/plugin/provider/openai.ts
@@ -20,7 +20,8 @@ const pollingSafetyMargin = 3000
 const codexBaseURL = "https://chatgpt.com/backend-api/codex"
 const browserMethodID = Integration.MethodID.make("chatgpt-browser")
 const headlessMethodID = Integration.MethodID.make("chatgpt-headless")
-const codexAllowed = new Set(["gpt-5.5", "gpt-5.3-codex-spark", "gpt-5.4", "gpt-5.4-mini"])
+// ChatGPT accounts lost gpt-5.4 and gpt-5.4-mini in Codex on 2026-08-31 (replacements: gpt-5.6-terra, gpt-5.6-luna).
+const codexAllowed = new Set(["gpt-5.5", "gpt-5.3-codex-spark"])
 const codexDisallowed = new Set(["gpt-5.5-pro", "gpt-5.6"])
 
 type Pkce = {
diff --git a/packages/core/test/plugin/provider-openai.test.ts b/packages/core/test/plugin/provider-openai.test.ts
index 992d0295bc2..e7e8b661033 100644
--- a/packages/core/test/plugin/provider-openai.test.ts
+++ b/packages/core/test/plugin/provider-openai.test.ts
@@ -164,11 +164,7 @@ describe("OpenAIPlugin", () => {
       expect(eligible.enabled).toBe(true)
       expect(required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.5-pro"))).enabled).toBe(false)
       expect(required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.4-pro"))).enabled).toBe(false)
-      expect(required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.4"))).limit).toEqual({
-        context: 400_000,
-        input: 272_000,
-        output: 64_000,
-      })
+      expect(required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.4"))).enabled).toBe(false)
       expect(required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.6"))).enabled).toBe(false)
       const gpt56 = required(yield* catalog.model.get(Provider.ID.openai, Model.ID.make("gpt-5.6-sol")))
       expect(gpt56.enabled).toBe(true)