refactor(client): simplify local service lifecycle

packages/docs/build/client.mdx

@@ -70,6 +70,33 @@ for await (const event of client.event.subscribe()) {
 }
 ```
 
+## Local service
+
+`Service` discovers and manages the local OpenCode background service from a
+Node application. The Promise API uses Node APIs directly and does not require
+Effect or `@effect/platform-node`.
+
+- `Service.discover()` returns a healthy registered endpoint without starting
+  a process.
+- `Service.start()` reuses a compatible service or starts one when needed.
+- `Service.stop()` stops the registered service.
+- `Service.headers(endpoint)` creates the authentication headers for a client.
+
+```ts
+import { OpenCode } from "@opencode-ai/client"
+import { Service } from "@opencode-ai/client/service"
+
+const endpoint = await Service.start()
+const client = OpenCode.make({
+  baseUrl: endpoint.url,
+  headers: Service.headers(endpoint),
+})
+
+const health = await client.health.get()
+```
+
+Import the native Promise service API from `@opencode-ai/client/service`.
+
 ## Effect
 
 OpenCode provides a first-class Effect client through the
@@ -106,16 +133,11 @@ const session = await Effect.runPromise(
 Streaming operations, including `client.event.subscribe()` and
 `client.session.log(...)`, return Effect `Stream` values.
 
-### Service
+### Local service
 
-`Service` discovers and manages the local OpenCode background service from a
-Node application:
-
-- `Service.discover()` returns a healthy registered endpoint without starting
-  a process.
-- `Service.start()` reuses a compatible service or starts one when needed.
-- `Service.stop()` stops the registered service.
-- `Service.headers(endpoint)` creates the authentication headers for a client.
+The Effect entrypoint exposes the same service lifecycle operations as Effect
+values. Add `@effect/platform-node` and provide its filesystem layer when
+running service operations.
 
 ```sh
 bun add @effect/platform-node
@@ -123,7 +145,8 @@ bun add @effect/platform-node
 
 ```ts
 import { NodeFileSystem } from "@effect/platform-node"
-import { OpenCode, Service } from "@opencode-ai/client/effect"
+import { OpenCode } from "@opencode-ai/client/effect"
+import { Service } from "@opencode-ai/client/effect/service"
 import { Effect } from "effect"
 import { FetchHttpClient } from "effect/unstable/http"