Add Vertex AI routing support (#753)

* add Vertex AI routing support

* include Vertex smokes in action CI

models.test.ts

@@ -3,6 +3,7 @@ import {
   getModelEnvVars,
   getModelProvider,
   isBedrockAnthropicId,
+  isVertexAnthropicId,
   modelAliases,
   parseModel,
   providers,
@@ -258,6 +259,20 @@ describe("isBedrockAnthropicId", () => {
   });
 });
 
+describe("isVertexAnthropicId", () => {
+  it("matches Claude Vertex IDs by anchored prefix", () => {
+    expect(isVertexAnthropicId("claude-opus-4-1@20250805")).toBe(true);
+  });
+
+  it("rejects Gemini IDs", () => {
+    expect(isVertexAnthropicId("gemini-2.5-pro")).toBe(false);
+  });
+
+  it("ignores Anthropic substrings outside the prefix", () => {
+    expect(isVertexAnthropicId("publishers/anthropic/models/claude-opus-4-1")).toBe(false);
+  });
+});
+
 describe("providers registry", () => {
   it("every provider has envVars", () => {
     for (const [key, config] of Object.entries(providers)) {