test(think-mode): update tests for variant-only behavior

Update test assertions to verify hook only sets output.message.variant
and no longer modifies output.message.model.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

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

@@ -43,7 +43,7 @@ describe("createThinkModeHook", () => {
     clearThinkModeState(sessionID)
   })
 
-  it("sets high variant and switches model when think keyword is present", async () => {
+  it("sets high variant when think keyword is present", async () => {
     // given
     const hook = createThinkModeHook()
     const input = createHookInput({
@@ -58,13 +58,10 @@ describe("createThinkModeHook", () => {
 
     // then
     expect(output.message.variant).toBe("high")
-    expect(output.message.model).toEqual({
+    expect(output.message.model).toBeUndefined()
-      providerID: "github-copilot",
-      modelID: "claude-opus-4-6-high",
-    })
   })
 
-  it("supports dotted model IDs by switching to normalized high variant", async () => {
+  it("sets high variant for dotted model IDs", async () => {
     // given
     const hook = createThinkModeHook()
     const input = createHookInput({
@@ -79,10 +76,7 @@ describe("createThinkModeHook", () => {
 
     // then
     expect(output.message.variant).toBe("high")
-    expect(output.message.model).toEqual({
+    expect(output.message.model).toBeUndefined()
-      providerID: "github-copilot",
-      modelID: "gpt-5-4-high",
-    })
   })
 
   it("skips when message variant is already set", async () => {