fix: recognize google-vertex-anthropic as Claude provider (#1700)

src/hooks/think-mode/index.test.ts

@@ -214,6 +214,27 @@ describe("createThinkModeHook integration", () => {
       expect(message.thinking).toBeDefined()
     })
 
+    it("should work for direct google-vertex-anthropic provider", async () => {
+      //#given direct google-vertex-anthropic provider
+      const hook = createThinkModeHook()
+      const input = createMockInput(
+        "google-vertex-anthropic",
+        "claude-opus-4-6",
+        "think deeply"
+      )
+
+      //#when the chat.params hook is called
+      await hook["chat.params"](input, sessionID)
+
+      //#then should upgrade model and inject Claude thinking config
+      const message = input.message as MessageWithInjectedProps
+      expect(input.message.model?.modelID).toBe("claude-opus-4-6-high")
+      expect(message.thinking).toBeDefined()
+      expect((message.thinking as Record<string, unknown>)?.budgetTokens).toBe(
+        64000
+      )
+    })
+
     it("should still work for direct google provider", async () => {
       // given direct google provider
       const hook = createThinkModeHook()

src/hooks/think-mode/switcher.test.ts

@@ -266,6 +266,24 @@ describe("think-mode switcher", () => {
       expect((config?.thinking as Record<string, unknown>)?.type).toBe("enabled")
     })
 
+    it("should work for direct google-vertex-anthropic provider", () => {
+      //#given direct google-vertex-anthropic provider
+      const config = getThinkingConfig(
+        "google-vertex-anthropic",
+        "claude-opus-4-6"
+      )
+
+      //#when thinking config is resolved
+
+      //#then it should return anthropic-style thinking config
+      expect(config).not.toBeNull()
+      expect(config?.thinking).toBeDefined()
+      expect((config?.thinking as Record<string, unknown>)?.type).toBe("enabled")
+      expect((config?.thinking as Record<string, unknown>)?.budgetTokens).toBe(
+        64000
+      )
+    })
+
     it("should still work for direct google provider", () => {
       // given direct google provider
       const config = getThinkingConfig("google", "gemini-3-pro")
@@ -314,6 +332,17 @@ describe("think-mode switcher", () => {
       expect(config.maxTokens).toBe(128000)
     })
 
+    it("should have correct structure for google-vertex-anthropic", () => {
+      //#given google-vertex-anthropic config entry
+      const config = THINKING_CONFIGS["google-vertex-anthropic"]
+
+      //#when structure is validated
+
+      //#then it should match anthropic style structure
+      expect(config.thinking).toBeDefined()
+      expect(config.maxTokens).toBe(128000)
+    })
+
     it("should have correct structure for google", () => {
       const config = THINKING_CONFIGS.google
       expect(config.providerOptions).toBeDefined()

src/hooks/think-mode/switcher.ts

@@ -121,6 +121,13 @@ export const THINKING_CONFIGS = {
     },
     maxTokens: 128000,
   },
+  "google-vertex-anthropic": {
+    thinking: {
+      type: "enabled",
+      budgetTokens: 64000,
+    },
+    maxTokens: 128000,
+  },
   "amazon-bedrock": {
     reasoningConfig: {
       type: "enabled",
@@ -164,6 +171,7 @@ export const THINKING_CONFIGS = {
 
 const THINKING_CAPABLE_MODELS = {
   anthropic: ["claude-sonnet-4", "claude-opus-4", "claude-3"],
+  "google-vertex-anthropic": ["claude-sonnet-4", "claude-opus-4", "claude-3"],
   "amazon-bedrock": ["claude", "anthropic"],
   google: ["gemini-2", "gemini-3"],
   "google-vertex": ["gemini-2", "gemini-3"],