From 10dbb213809e2a8280f6210dcdfea80b6fb1c50c Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Tue, 14 Apr 2026 13:24:46 +0100
Subject: [PATCH] fix(models): normalize google-vertex flash-lite ids

---
 extensions/google/api.test.ts        | 31 ++++++++++++++++++++++++++++
 extensions/google/provider-policy.ts | 19 +++++++++++------
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/extensions/google/api.test.ts b/extensions/google/api.test.ts
index 954c11cb2d0..a53a88f58f6 100644
--- a/extensions/google/api.test.ts
+++ b/extensions/google/api.test.ts
@@ -4,6 +4,7 @@ import {
   isGoogleGenerativeAiApi,
   normalizeGoogleApiBaseUrl,
   normalizeGoogleGenerativeAiBaseUrl,
+  normalizeGoogleProviderConfig,
   parseGeminiAuth,
   resolveGoogleGenerativeAiHttpRequestConfig,
   resolveGoogleGenerativeAiApiOrigin,
@@ -106,6 +107,36 @@ describe("google generative ai helpers", () => {
     });
   });
 
+  it("normalizes google-vertex model ids without rewriting the OpenAI-compatible baseUrl", () => {
+    expect(
+      normalizeGoogleProviderConfig("google-vertex", {
+        api: "openai-completions",
+        baseUrl:
+          "https://aiplatform.googleapis.com/v1/projects/test/locations/us-central1/endpoints/openapi",
+        models: [
+          {
+            id: "gemini-3.1-flash-lite",
+            name: "Gemini Flash Lite",
+            input: ["text"],
+            reasoning: false,
+            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+            contextWindow: 1,
+            maxTokens: 1,
+          },
+        ],
+      }),
+    ).toMatchObject({
+      api: "openai-completions",
+      baseUrl:
+        "https://aiplatform.googleapis.com/v1/projects/test/locations/us-central1/endpoints/openapi",
+      models: [
+        expect.objectContaining({
+          id: "gemini-3.1-flash-lite-preview",
+        }),
+      ],
+    });
+  });
+
   it("derives the Gemini API origin without duplicating /v1beta", () => {
     expect(resolveGoogleGenerativeAiApiOrigin()).toBe("https://generativelanguage.googleapis.com");
     expect(resolveGoogleGenerativeAiApiOrigin("https://generativelanguage.googleapis.com")).toBe(
diff --git a/extensions/google/provider-policy.ts b/extensions/google/provider-policy.ts
index 5ed20e8dcda..4b1766b0a38 100644
--- a/extensions/google/provider-policy.ts
+++ b/extensions/google/provider-policy.ts
@@ -152,14 +152,21 @@ export function normalizeGoogleProviderConfig(
   provider: ModelProviderConfig,
 ): ModelProviderConfig {
   let nextProvider = provider;
+  const shouldNormalizeModelIds =
+    providerKey === "google-vertex" ||
+    shouldNormalizeGoogleGenerativeAiProviderConfig(providerKey, nextProvider);
 
-  if (shouldNormalizeGoogleGenerativeAiProviderConfig(providerKey, nextProvider)) {
+  if (shouldNormalizeModelIds) {
     const modelNormalized = normalizeProviderModels(nextProvider, normalizeGoogleModelId);
-    const normalizedBaseUrl = normalizeGoogleGenerativeAiBaseUrl(modelNormalized.baseUrl);
-    nextProvider =
-      normalizedBaseUrl !== modelNormalized.baseUrl
-        ? { ...modelNormalized, baseUrl: normalizedBaseUrl ?? modelNormalized.baseUrl }
-        : modelNormalized;
+    if (shouldNormalizeGoogleGenerativeAiProviderConfig(providerKey, modelNormalized)) {
+      const normalizedBaseUrl = normalizeGoogleGenerativeAiBaseUrl(modelNormalized.baseUrl);
+      nextProvider =
+        normalizedBaseUrl !== modelNormalized.baseUrl
+          ? { ...modelNormalized, baseUrl: normalizedBaseUrl ?? modelNormalized.baseUrl }
+          : modelNormalized;
+    } else {
+      nextProvider = modelNormalized;
+    }
   }
 
   if (providerKey === "google-antigravity") {