fix(anthropic-effort): clamp variant against mutable request message

src/plugin/chat-params.test.ts

@@ -35,4 +35,37 @@ describe("createChatParamsHandler", () => {
     //#then
     expect(called).toBe(true)
   })
+
+  test("passes the original mutable message object to chat.params hooks", async () => {
+    //#given
+    const handler = createChatParamsHandler({
+      anthropicEffort: {
+        "chat.params": async (input) => {
+          input.message.variant = "high"
+        },
+      },
+    })
+
+    const message = { variant: "max" }
+    const input = {
+      sessionID: "ses_chat_params",
+      agent: { name: "sisyphus" },
+      model: { providerID: "opencode", modelID: "claude-sonnet-4-6" },
+      provider: { id: "opencode" },
+      message,
+    }
+
+    const output = {
+      temperature: 0.1,
+      topP: 1,
+      topK: 1,
+      options: {},
+    }
+
+    //#when
+    await handler(input, output)
+
+    //#then
+    expect(message.variant).toBe("high")
+  })
 })