refactor(tool): destroy Truncate facade, effectify Tool.define (#22093)

packages/opencode/test/tool/task.test.ts

@@ -10,6 +10,7 @@ import type { SessionPrompt } from "../../src/session/prompt"
 import { MessageID, PartID } from "../../src/session/schema"
 import { ModelID, ProviderID } from "../../src/provider/schema"
 import { TaskTool, type TaskPromptOps } from "../../src/tool/task"
+import { Truncate } from "../../src/tool/truncate"
 import { ToolRegistry } from "../../src/tool/registry"
 import { provideTmpdirInstance } from "../fixture/fixture"
 import { testEffect } from "../lib/effect"
@@ -29,6 +30,7 @@ const it = testEffect(
     Config.defaultLayer,
     CrossSpawnSpawner.defaultLayer,
     Session.defaultLayer,
+    Truncate.defaultLayer,
     ToolRegistry.defaultLayer,
   ),
 )