refactor(effect): build todowrite tool from Todo service (#20789)

Co-authored-by: Juan Pablo Carranza Hurtado <52012198+jpcarranza94@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/opencode/src/tool/todo.ts

@@ -1,31 +1,48 @@
 import z from "zod"
+import { Effect } from "effect"
 import { Tool } from "./tool"
 import DESCRIPTION_WRITE from "./todowrite.txt"
 import { Todo } from "../session/todo"
 
-export const TodoWriteTool = Tool.define("todowrite", {
-  description: DESCRIPTION_WRITE,
-  parameters: z.object({
-    todos: z.array(z.object(Todo.Info.shape)).describe("The updated todo list"),
-  }),
-  async execute(params, ctx) {
-    await ctx.ask({
-      permission: "todowrite",
-      patterns: ["*"],
-      always: ["*"],
-      metadata: {},
-    })
-
-    await Todo.update({
-      sessionID: ctx.sessionID,
-      todos: params.todos,
-    })
-    return {
-      title: `${params.todos.filter((x) => x.status !== "completed").length} todos`,
-      output: JSON.stringify(params.todos, null, 2),
-      metadata: {
-        todos: params.todos,
-      },
-    }
-  },
+const parameters = z.object({
+  todos: z.array(z.object(Todo.Info.shape)).describe("The updated todo list"),
 })
+
+type Metadata = {
+  todos: Todo.Info[]
+}
+
+export const TodoWriteTool = Tool.defineEffect<typeof parameters, Metadata, Todo.Service>(
+  "todowrite",
+  Effect.gen(function* () {
+    const todo = yield* Todo.Service
+
+    return {
+      description: DESCRIPTION_WRITE,
+      parameters,
+      async execute(params: z.infer<typeof parameters>, ctx: Tool.Context<Metadata>) {
+        await ctx.ask({
+          permission: "todowrite",
+          patterns: ["*"],
+          always: ["*"],
+          metadata: {},
+        })
+
+        await todo
+          .update({
+            sessionID: ctx.sessionID,
+            todos: params.todos,
+          })
+          .pipe(Effect.runPromise)
+
+        return {
+          title: `${params.todos.filter((x) => x.status !== "completed").length} todos`,
+          output: JSON.stringify(params.todos, null, 2),
+          metadata: {
+            todos: params.todos,
+          },
+        }
+      },
+    } satisfies Tool.Def<typeof parameters, Metadata>
+  }),
+)