refactor(client): rename service start to ensure

packages/docs/build/client.mdx

@@ -70,23 +70,23 @@ for await (const event of client.event.subscribe()) {
 }
 ```
 
-## Local service
+## Local background 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`.
+The main client entrypoints are browser-compatible and do not include local
+process management. In a Node application, import the native Promise service
+API from `@opencode-ai/client/service`.
 
 - `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.ensure()` returns a compatible service, starting one when needed.
+- `Service.stop()` stops the exact registered service instance.
 - `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 endpoint = await Service.ensure()
 const client = OpenCode.make({
   baseUrl: endpoint.url,
   headers: Service.headers(endpoint),
@@ -95,7 +95,22 @@ const client = OpenCode.make({
 const health = await client.health.get()
 ```
 
-Import the native Promise service API from `@opencode-ai/client/service`.
+`Service.ensure()` accepts an optional registration file, required version,
+service command, and `onStart` callback:
+
+```ts
+const endpoint = await Service.ensure({
+  file: "/var/run/opencode/service.json",
+  version: "2.0.0",
+  command: ["opencode", "serve", "--service"],
+  onStart(reason, previousVersion) {
+    console.log(reason, previousVersion)
+  },
+})
+```
+
+Omit these options to use the standard registration path and
+`opencode serve --service` command.
 
 ## Effect
 
@@ -133,11 +148,11 @@ const session = await Effect.runPromise(
 Streaming operations, including `client.event.subscribe()` and
 `client.session.log(...)`, return Effect `Stream` values.
 
-### Local service
+### Local background service
 
-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.
+The Node-only `@opencode-ai/client/effect/service` entrypoint exposes the same
+operations as Effect values. Add `@effect/platform-node` and provide its
+filesystem layer when running them.
 
 ```sh
 bun add @effect/platform-node
@@ -151,7 +166,7 @@ import { Effect } from "effect"
 import { FetchHttpClient } from "effect/unstable/http"
 
 const program = Effect.gen(function* () {
-  const endpoint = yield* Service.start()
+  const endpoint = yield* Service.ensure()
   const client = yield* OpenCode.make({
     baseUrl: endpoint.url,
     headers: Service.headers(endpoint),