diff --git a/packages/cli/src/commands/handlers/api.ts b/packages/cli/src/commands/handlers/api.ts
index 82d273c25de..de4d1a2b876 100644
--- a/packages/cli/src/commands/handlers/api.ts
+++ b/packages/cli/src/commands/handlers/api.ts
@@ -4,7 +4,6 @@ import { Commands } from "../commands"
 import { Runtime } from "../../framework/runtime"
 import { Service } from "@opencode-ai/client/effect"
 import { ServiceConfig } from "../../services/service-config"
-import type { Transport } from "@opencode-ai/client/effect"
 
 const methods = new Set(["delete", "get", "head", "options", "patch", "post", "put"])
 
@@ -61,7 +60,7 @@ export function rawRequest(input: readonly string[]) {
 }
 
 function resolveRequest(
-  transport: Transport,
+  transport: Service.Transport,
   input: readonly string[],
   params: Record<string, string>,
 ) {
diff --git a/packages/cli/src/commands/handlers/default.ts b/packages/cli/src/commands/handlers/default.ts
index 98b0c9b3c93..32e542e6347 100644
--- a/packages/cli/src/commands/handlers/default.ts
+++ b/packages/cli/src/commands/handlers/default.ts
@@ -3,7 +3,6 @@ import { Commands } from "../commands"
 import { Runtime } from "../../framework/runtime"
 import { Effect, Option } from "effect"
 import { Service } from "@opencode-ai/client/effect"
-import type { Transport } from "@opencode-ai/client/effect"
 import { ServiceConfig } from "../../services/service-config"
 import { Standalone } from "../../services/standalone"
 import { Updater } from "../../services/updater"
@@ -23,7 +22,7 @@ export default Runtime.handler(Commands, (input) =>
         return {
           url: server,
           headers: password ? { authorization: "Basic " + btoa("opencode:" + password) } : undefined,
-        } satisfies Transport
+        } satisfies Service.Transport
       }
       if (input.standalone) return yield* Standalone.transport()
       const options = yield* ServiceConfig.options()
diff --git a/packages/cli/src/commands/handlers/serve.ts b/packages/cli/src/commands/handlers/serve.ts
index 80cf6cba9f1..d6b6938ee32 100644
--- a/packages/cli/src/commands/handlers/serve.ts
+++ b/packages/cli/src/commands/handlers/serve.ts
@@ -14,6 +14,7 @@ import { InstallationVersion } from "@opencode-ai/core/installation/version"
 import { createOpencodeClient } from "@opencode-ai/sdk/v2/client"
 import { Commands } from "../commands"
 import { Runtime } from "../../framework/runtime"
+import { Service } from "@opencode-ai/client/effect"
 import { ServiceConfig } from "../../services/service-config"
 import { Updater } from "../../services/updater"
 import { randomBytes, randomUUID } from "crypto"
@@ -63,8 +64,11 @@ export default Runtime.handler(
 // not a startup lock: the atomic rename elects the latest writer, the watcher
 // self-evicts losers, and the finalizer id-guard keeps an exiting server from
 // deleting its successor's registration.
-const RegistrationId = Schema.Struct({ id: Schema.optional(Schema.String) })
-const decodeRegistrationId = Schema.decodeUnknownEffect(Schema.fromJsonString(RegistrationId))
+// Written and read through Service.Info so the file the server registers is
+// provably the contract clients discover with.
+const infoJson = Schema.fromJsonString(Service.Info)
+const encodeInfo = Schema.encodeEffect(infoJson)
+const decodeInfo = Schema.decodeUnknownEffect(infoJson)
 
 const register = Effect.fnUntraced(function* (address: HttpServer.Address) {
   const fs = yield* FileSystem.FileSystem
@@ -73,20 +77,17 @@ const register = Effect.fnUntraced(function* (address: HttpServer.Address) {
   const secret = yield* ServiceConfig.password()
   const temp = file + "." + id + ".tmp"
   yield* fs.makeDirectory(path.dirname(file), { recursive: true })
-  yield* fs.writeFileString(
-    temp,
-    JSON.stringify({
-      id,
-      version: InstallationVersion,
-      url: HttpServer.formatAddress(address),
-      pid: process.pid,
-      password: secret,
-    }),
-    { mode: 0o600 },
-  )
+  const encoded = yield* encodeInfo({
+    id,
+    version: InstallationVersion,
+    url: HttpServer.formatAddress(address),
+    pid: process.pid,
+    password: secret,
+  })
+  yield* fs.writeFileString(temp, encoded, { mode: 0o600 })
   yield* fs.rename(temp, file)
   const currentID = fs.readFileString(file).pipe(
-    Effect.flatMap(decodeRegistrationId),
+    Effect.flatMap(decodeInfo),
     Effect.map((info) => info.id),
     Effect.orElseSucceed(() => undefined),
   )
diff --git a/packages/cli/src/services/service-config.ts b/packages/cli/src/services/service-config.ts
index 356472e3595..ecdd5bf19a0 100644
--- a/packages/cli/src/services/service-config.ts
+++ b/packages/cli/src/services/service-config.ts
@@ -5,7 +5,7 @@ import { Effect, FileSystem, Schema } from "effect"
 import { randomBytes } from "crypto"
 import path from "path"
 
-// The CLI's service configuration file, plus the ServiceOptions binding that
+// The CLI's service configuration file, plus the Service.Options binding that
 // points the client package's service operations at this CLI: which
 // registration file (by channel), which version, and how to spawn opencode.
 
diff --git a/packages/cli/src/tui.ts b/packages/cli/src/tui.ts
index 577a7be4936..a535309d422 100644
--- a/packages/cli/src/tui.ts
+++ b/packages/cli/src/tui.ts
@@ -5,11 +5,11 @@ import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { Global } from "@opencode-ai/core/global"
 import { loadBuiltinPlugins } from "@opencode-ai/tui/builtins"
 import { OpenCode } from "@opencode-ai/client/promise"
-import type { Transport } from "@opencode-ai/client/effect"
+import type { Service } from "@opencode-ai/client/effect"
 import { createOpencodeClient } from "@opencode-ai/sdk/v2/client"
 import type { Args } from "@opencode-ai/tui/context/args"
 
-export function runTui(transport: Transport, args: Args, discover?: () => Promise<Transport>) {
+export function runTui(transport: Service.Transport, args: Args, discover?: () => Promise<Service.Transport>) {
   const config = TuiConfig.resolve({}, { terminalSuspend: false })
   let disposeSlots: (() => void) | undefined
   return Effect.gen(function* () {
diff --git a/packages/client/src/effect/index.ts b/packages/client/src/effect/index.ts
index 1a69a358cc6..23e6d55c748 100644
--- a/packages/client/src/effect/index.ts
+++ b/packages/client/src/effect/index.ts
@@ -2,7 +2,6 @@
 // Core or Server. Preserve these datatype exports so internal model reorganizations do not require caller migrations.
 export * from "./generated/index"
 export { Service } from "./service.js"
-export type { Transport, ServiceOptions } from "./service.js"
 export { Agent } from "@opencode-ai/schema/agent"
 export { Command } from "@opencode-ai/schema/command"
 export { Credential } from "@opencode-ai/schema/credential"
diff --git a/packages/client/src/effect/service.ts b/packages/client/src/effect/service.ts
index 93cbdd03fce..ca428f5aa62 100644
--- a/packages/client/src/effect/service.ts
+++ b/packages/client/src/effect/service.ts
@@ -16,7 +16,7 @@ export type Transport = {
   readonly headers?: RequestInit["headers"]
 }
 
-export type ServiceOptions = {
+export type Options = {
   // Absolute path to the service registration file. Defaults to
   // opencode/service.json in the XDG state directory.
   readonly file?: string
@@ -30,21 +30,21 @@ export type ServiceOptions = {
 
 // Read-only lookup: registration file plus health check and version gate.
 // Never spawns; escalation to start() is the caller's policy.
-export const discover = Effect.fn("service.discover")(function* (options: ServiceOptions = {}) {
-  const registration = yield* read(options.file)
-  if (registration === undefined) return undefined
-  if (options.version !== undefined && registration.version !== options.version) return undefined
-  const found = yield* probe(registration)
+export const discover = Effect.fn("service.discover")(function* (options: Options = {}) {
+  const info = yield* read(options.file)
+  if (info === undefined) return undefined
+  if (options.version !== undefined && info.version !== options.version) return undefined
+  const found = yield* probe(info)
   return found?.transport
 })
 
 // Idempotent ensure-running: reuses a healthy compatible server, replaces a
 // version-mismatched one, and otherwise spawns the service command detached.
-export const start = Effect.fn("service.start")(function* (options: ServiceOptions = {}) {
+export const start = Effect.fn("service.start")(function* (options: Options = {}) {
   const compatible = yield* discover(options)
   if (compatible !== undefined) return compatible
   const mismatched = yield* find(options)
-  if (mismatched !== undefined) yield* kill(mismatched.registration, options).pipe(Effect.ignore)
+  if (mismatched !== undefined) yield* kill(mismatched.info, options).pipe(Effect.ignore)
 
   const [command, ...args] = options.command ?? ["opencode", "serve", "--service"]
   if (command === undefined) return yield* Effect.fail(new Error("Missing service command"))
@@ -64,10 +64,10 @@ export const start = Effect.fn("service.start")(function* (options: ServiceOptio
   )
 })
 
-export const stop = Effect.fn("service.stop")(function* (options: ServiceOptions = {}) {
+export const stop = Effect.fn("service.stop")(function* (options: Options = {}) {
   const fs = yield* FileSystem.FileSystem
   const existing = yield* find(options)
-  if (existing !== undefined) yield* kill(existing.registration, options)
+  if (existing !== undefined) yield* kill(existing.info, options)
   yield* fs.remove(options.file ?? fallback()).pipe(Effect.ignore)
 })
 
@@ -80,18 +80,18 @@ function auth(password: string): RequestInit["headers"] {
   return { authorization: "Basic " + btoa("opencode:" + password) }
 }
 
-const Registration = Schema.Struct({
+export const Info = Schema.Struct({
   id: Schema.optional(Schema.String),
   version: Schema.optional(Schema.String),
   url: Schema.String,
   pid: Schema.Int.check(Schema.isGreaterThan(0)),
   password: Schema.optional(Schema.String),
 })
-type Registration = typeof Registration.Type
+export type Info = typeof Info.Type
 
-const decode = Schema.decodeUnknownEffect(Schema.fromJsonString(Registration))
+const decode = Schema.decodeUnknownEffect(Schema.fromJsonString(Info))
 
-// A missing or corrupt file means no valid registration; callers treat both
+// A missing or corrupt file means no valid info; callers treat both
 // the same (the registering server self-evicts, clients rediscover).
 const read = Effect.fnUntraced(function* (file?: string) {
   const fs = yield* FileSystem.FileSystem
@@ -101,14 +101,14 @@ const read = Effect.fnUntraced(function* (file?: string) {
 })
 
 type LocalService = {
-  readonly registration: Registration
+  readonly info: Info
   readonly transport: Transport
 }
 
-const probe = Effect.fnUntraced(function* (registration: Registration) {
-  const headers = registration.password === undefined ? undefined : auth(registration.password)
+const probe = Effect.fnUntraced(function* (info: Info) {
+  const headers = info.password === undefined ? undefined : auth(info.password)
   const healthy = yield* Effect.tryPromise(() =>
-    fetch(new URL("/api/health", registration.url), {
+    fetch(new URL("/api/health", info.url), {
       headers,
       signal: AbortSignal.timeout(2_000),
     }),
@@ -117,15 +117,15 @@ const probe = Effect.fnUntraced(function* (registration: Registration) {
     Effect.orElseSucceed(() => false),
   )
   if (!healthy) return undefined
-  return { registration, transport: { url: registration.url, headers } } satisfies LocalService
+  return { info, transport: { url: info.url, headers } } satisfies LocalService
 })
 
 // Health-checked lookup without the version gate: lifecycle operations must be
 // able to see (and replace or stop) a server from a different version.
-const find = Effect.fnUntraced(function* (options: ServiceOptions) {
-  const registration = yield* read(options.file)
-  if (registration === undefined) return undefined
-  return yield* probe(registration)
+const find = Effect.fnUntraced(function* (options: Options) {
+  const info = yield* read(options.file)
+  if (info === undefined) return undefined
+  return yield* probe(info)
 })
 
 // 50ms cadence bounded at ~5s, shared by stop escalation and start readiness.
@@ -142,22 +142,22 @@ const stopped = Effect.fnUntraced(function* (pid: number) {
   return yield* Effect.fail(new Error(`Server process ${pid} is still running`))
 })
 
-function same(left: Registration, right: Registration) {
+function same(left: Info, right: Info) {
   return left.id === right.id && left.version === right.version && left.url === right.url && left.pid === right.pid
 }
 
-const kill = Effect.fnUntraced(function* (info: Registration, options: ServiceOptions) {
+const kill = Effect.fnUntraced(function* (info: Info, options: Options) {
   // A stale registration may point at a PID that has since been reused by
   // another process. Only signal the PID after authenticating the server.
   const current = yield* find(options)
-  if (current === undefined || !same(current.registration, info)) return
+  if (current === undefined || !same(current.info, info)) return
 
   yield* signal(info.pid, "SIGTERM")
   const done = yield* stopped(info.pid).pipe(Effect.retry(poll), Effect.option)
   if (Option.isSome(done)) return
 
   const latest = yield* find(options)
-  if (latest === undefined || !same(latest.registration, info)) return
+  if (latest === undefined || !same(latest.info, info)) return
   yield* signal(info.pid, "SIGKILL")
   yield* stopped(info.pid).pipe(Effect.retry(poll))
 })
diff --git a/packages/client/src/promise/index.ts b/packages/client/src/promise/index.ts
index 61bdcdf888f..e9e848b160b 100644
--- a/packages/client/src/promise/index.ts
+++ b/packages/client/src/promise/index.ts
@@ -1,4 +1,3 @@
 export * from "./generated/index"
-export type { Transport } from "../effect/service.js"
 export type { EventSubscribeOutput as OpenCodeEvent } from "./generated/types"
 export type OpenCodeClient = ReturnType<typeof import("./generated/client").make>