restore fast mode for nightly gpt models

Author: Marve10s

apps/server/src/provider/Layers/CodexProvider.test.ts

@@ -0,0 +1,60 @@
+import { describe, expect, it } from "vitest";
+import type * as CodexSchema from "effect-codex-app-server/schema";
+
+import { parseCodexModelListResponse } from "./CodexProvider.ts";
+
+function makeModel(
+  overrides: Partial<CodexSchema.V2ModelListResponse__Model> = {},
+): CodexSchema.V2ModelListResponse__Model {
+  return {
+    id: "gpt-5.4",
+    model: "gpt-5.4",
+    upgrade: null,
+    upgradeInfo: null,
+    availabilityNux: null,
+    displayName: "gpt-5.4",
+    description: "Latest frontier agentic coding model.",
+    hidden: false,
+    supportedReasoningEfforts: [
+      {
+        reasoningEffort: "medium",
+        description: "Balances speed and reasoning depth for everyday tasks",
+      },
+    ],
+    defaultReasoningEffort: "medium",
+    inputModalities: ["text", "image"],
+    supportsPersonality: true,
+    isDefault: true,
+    ...overrides,
+  };
+}
+
+describe("parseCodexModelListResponse", () => {
+  it("preserves fast mode for GPT-5 models when app-server omits additionalSpeedTiers", () => {
+    const [model] = parseCodexModelListResponse({
+      data: [makeModel()],
+      nextCursor: null,
+    });
+
+    expect(model).toBeDefined();
+    expect(model?.capabilities).toMatchObject({
+      supportsFastMode: true,
+    });
+  });
+
+  it("honors an explicit empty additionalSpeedTiers list", () => {
+    const [model] = parseCodexModelListResponse({
+      data: [
+        makeModel({
+          additionalSpeedTiers: [],
+        }),
+      ],
+      nextCursor: null,
+    });
+
+    expect(model).toBeDefined();
+    expect(model?.capabilities).toMatchObject({
+      supportsFastMode: false,
+    });
+  });
+});

apps/server/src/provider/Layers/CodexProvider.ts

@@ -84,13 +84,17 @@ function codexAccountAuthLabel(account: CodexSchema.V2GetAccountResponse["accoun
 function mapCodexModelCapabilities(
   model: CodexSchema.V2ModelListResponse__Model,
 ): ModelCapabilities {
+  const supportsFastMode = globalThis.Array.isArray(model.additionalSpeedTiers)
+    ? model.additionalSpeedTiers.includes("fast")
+    : /^gpt-5(?:[.-]|$)/.test(model.model);
+
   return {
     reasoningEffortLevels: model.supportedReasoningEfforts.map(({ reasoningEffort }) => ({
       value: reasoningEffort,
       label: REASONING_EFFORT_LABELS[reasoningEffort],
       ...(reasoningEffort === model.defaultReasoningEffort ? { isDefault: true } : {}),
     })),
-    supportsFastMode: (model.additionalSpeedTiers ?? []).includes("fast"),
+    supportsFastMode,
     supportsThinkingToggle: false,
     contextWindowOptions: [],
     promptInjectedEffortLevels: [],
@@ -104,7 +108,7 @@ const toDisplayName = (model: CodexSchema.V2ModelListResponse__Model): string =>
     .replace(/-([a-z])/g, (_, c) => "-" + c.toUpperCase());
 };
 
-function parseCodexModelListResponse(
+export function parseCodexModelListResponse(
   response: CodexSchema.V2ModelListResponse,
 ): ReadonlyArray<ServerProviderModel> {
   return response.data.map((model) => ({