diff --git a/packages/cordis/src/index.ts b/packages/cordis/src/index.ts
index 99a99e9..b2d4ddc 100644
--- a/packages/cordis/src/index.ts
+++ b/packages/cordis/src/index.ts
@@ -22,11 +22,9 @@ export class Context extends core.Context {
     this.baseDir = globalThis.process?.cwd() || ''
 
     this.provide('logger', undefined, true)
-    this.provide('schema', undefined, true)
     this.provide('timer', undefined, true)
 
     this.plugin(LoggerService)
-    this.plugin(SchemaService)
     this.plugin(TimerService)
   }
 }
@@ -34,6 +32,7 @@ export class Context extends core.Context {
 export abstract class Service<T = unknown, C extends Context = Context> extends core.Service<T, C> {
   /** @deprecated use `this.ctx.logger` instead */
   public logger: Logger
+  public schema: SchemaService
 
   constructor(...args: core.Spread<T>)
   constructor(ctx: C, ...args: core.Spread<T>)
@@ -41,6 +40,7 @@ export abstract class Service<T = unknown, C extends Context = Context> extends
   constructor(...args: any) {
     super(...args)
     this.logger = this.ctx.logger(this.name)
+    this.schema = new SchemaService(this.ctx)
   }
 
   [core.Service.setup]() {
diff --git a/packages/core/src/events.ts b/packages/core/src/events.ts
index 602db7d..35bf82e 100644
--- a/packages/core/src/events.ts
+++ b/packages/core/src/events.ts
@@ -82,7 +82,7 @@ export default class Lifecycle {
     // non-reusable plugin forks are not responsive to isolated service changes
     defineProperty(this.on('internal/before-service', function (this: Context, name) {
       for (const runtime of this.registry.values()) {
-        if (!runtime.using.includes(name)) continue
+        if (!runtime.inject[name]?.required) continue
         const scopes = runtime.isReusable ? runtime.children : [runtime]
         for (const scope of scopes) {
           if (!this[symbols.filter](scope.ctx)) continue
@@ -94,7 +94,7 @@ export default class Lifecycle {
 
     defineProperty(this.on('internal/service', function (this: Context, name) {
       for (const runtime of this.registry.values()) {
-        if (!runtime.using.includes(name)) continue
+        if (!runtime.inject[name]?.required) continue
         const scopes = runtime.isReusable ? runtime.children : [runtime]
         for (const scope of scopes) {
           if (!this[symbols.filter](scope.ctx)) continue
@@ -106,7 +106,7 @@ export default class Lifecycle {
     // inject in ancestor contexts
     const checkInject = (scope: EffectScope, name: string) => {
       if (!scope.runtime.plugin) return false
-      for (const key of scope.runtime.inject) {
+      for (const key in scope.runtime.inject) {
         if (name === ReflectService.resolveInject(scope.ctx, key)[0]) return true
       }
       return checkInject(scope.parent.scope, name)
diff --git a/packages/core/src/registry.ts b/packages/core/src/registry.ts
index dff1c90..c167555 100644
--- a/packages/core/src/registry.ts
+++ b/packages/core/src/registry.ts
@@ -3,13 +3,31 @@ import { Context } from './context.ts'
 import { ForkScope, MainScope } from './scope.ts'
 import { resolveConfig, symbols } from './utils.ts'
 
-export function isApplicable(object: Plugin) {
+function isApplicable(object: Plugin) {
   return object && typeof object === 'object' && typeof object.apply === 'function'
 }
 
-export interface Inject {
-  readonly required?: string[]
-  readonly optional?: string[]
+export type Inject = string[] | Dict<Inject.Meta>
+
+export namespace Inject {
+  export interface Meta {
+    required: boolean
+  }
+
+  export function resolve(inject: Inject | null | undefined) {
+    if (!inject) return {}
+    if (Array.isArray(inject)) {
+      return Object.fromEntries(inject.map(name => [name, { required: true }]))
+    }
+    const { required, optional, ...rest } = inject
+    if (Array.isArray(required)) {
+      Object.assign(rest, Object.fromEntries(required.map(name => [name, { required: true }])))
+    }
+    if (Array.isArray(optional)) {
+      Object.assign(rest, Object.fromEntries(optional.map(name => [name, { required: false }])))
+    }
+    return rest
+  }
 }
 
 export type Plugin<C extends Context = Context, T = any> =
@@ -23,7 +41,7 @@ export namespace Plugin {
     reactive?: boolean
     reusable?: boolean
     Config?: (config: any) => T
-    inject?: string[] | Inject
+    inject?: Inject
     intercept?: Dict<boolean>
   }
 
@@ -50,8 +68,8 @@ export type Spread<T> = undefined extends T ? [config?: T] : [config: T]
 declare module './context.ts' {
   export interface Context {
     /** @deprecated use `ctx.inject()` instead */
-    using(deps: string[] | Inject, callback: Plugin.Function<this, void>): ForkScope<this>
-    inject(deps: string[] | Inject, callback: Plugin.Function<this, void>): ForkScope<this>
+    using(deps: Inject, callback: Plugin.Function<this, void>): ForkScope<this>
+    inject(deps: Inject, callback: Plugin.Function<this, void>): ForkScope<this>
     plugin<T = undefined, S = T>(plugin: Plugin.Function<this, T> & Plugin.Transform<S, T>, ...args: Spread<S>): ForkScope<this>
     plugin<T = undefined, S = T>(plugin: Plugin.Constructor<this, T> & Plugin.Transform<S, T>, ...args: Spread<S>): ForkScope<this>
     plugin<T = undefined, S = T>(plugin: Plugin.Object<this, T> & Plugin.Transform<S, T>, ...args: Spread<S>): ForkScope<this>
@@ -135,11 +153,11 @@ export default class Registry<C extends Context = Context> {
     return this._internal.forEach(callback)
   }
 
-  using(inject: string[] | Inject, callback: Plugin.Function<C, void>) {
+  using(inject: Inject, callback: Plugin.Function<C, void>) {
     return this.inject(inject, callback)
   }
 
-  inject(inject: string[] | Inject, callback: Plugin.Function<C, void>) {
+  inject(inject: Inject, callback: Plugin.Function<C, void>) {
     return this.plugin({ inject, apply: callback, name: callback.name })
   }
 
diff --git a/packages/core/src/scope.ts b/packages/core/src/scope.ts
index 50dfd31..88817ab 100644
--- a/packages/core/src/scope.ts
+++ b/packages/core/src/scope.ts
@@ -1,4 +1,4 @@
-import { deepEqual, defineProperty, isNullable, remove } from 'cosmokit'
+import { deepEqual, defineProperty, Dict, isNullable, remove } from 'cosmokit'
 import { Context } from './context.ts'
 import { Inject, Plugin } from './registry.ts'
 import { isConstructor, resolveConfig } from './utils.ts'
@@ -167,7 +167,9 @@ export abstract class EffectScope<C extends Context = Context> {
   }
 
   get ready() {
-    return this.runtime.using.every(name => !isNullable(this.ctx.get(name)))
+    return Object.entries(this.runtime.inject).every(([name, inject]) => {
+      return !inject.required || !isNullable(this.ctx.get(name))
+    })
   }
 
   reset() {
@@ -303,8 +305,7 @@ export class MainScope<C extends Context = Context> extends EffectScope<C> {
   runtime = this
   schema: any
   name?: string
-  using: string[] = []
-  inject = new Set<string>()
+  inject: Dict<Inject.Meta> = Object.create(null)
   forkables: Function[] = []
   children: ForkScope<C>[] = []
   isReusable?: boolean = false
@@ -336,28 +337,11 @@ export class MainScope<C extends Context = Context> extends EffectScope<C> {
     return true
   }
 
-  private setInject(inject?: string[] | Inject): void {
-    if (Array.isArray(inject)) {
-      for (const name of inject) {
-        this.using.push(name)
-        this.inject.add(name)
-      }
-    } else if (inject) {
-      for (const name of inject.required || []) {
-        this.using.push(name)
-        this.inject.add(name)
-      }
-      for (const name of inject.optional || []) {
-        this.inject.add(name)
-      }
-    }
-  }
-
   private setup() {
     const { name } = this.plugin
     if (name && name !== 'apply') this.name = name
     this.schema = this.plugin['Config'] || this.plugin['schema']
-    this.setInject(this.plugin['using'] || this.plugin['inject'])
+    this.inject = Inject.resolve(this.plugin['using'] || this.plugin['inject'])
     this.isReusable = this.plugin['reusable']
     this.isReactive = this.plugin['reactive']
     this.context.emit('internal/runtime', this)
diff --git a/packages/core/src/utils.ts b/packages/core/src/utils.ts
index 9b4d947..e9d802e 100644
--- a/packages/core/src/utils.ts
+++ b/packages/core/src/utils.ts
@@ -10,6 +10,7 @@ export const symbols = {
   // internal symbols
   shadow: Symbol.for('cordis.shadow'),
   receiver: Symbol.for('cordis.receiver'),
+  original: Symbol.for('cordis.original'),
 
   // context symbols
   source: Symbol.for('cordis.source') as typeof Context.source,
@@ -133,6 +134,7 @@ function createTraceable(ctx: Context, value: any, tracker: Tracker, noTrap?: bo
   }
   const proxy = new Proxy(value, {
     get: (target, prop, receiver) => {
+      if (prop === symbols.original) return target
       if (prop === tracker.property) return ctx
       if (typeof prop === 'symbol') {
         return Reflect.get(target, prop, receiver)
@@ -152,6 +154,7 @@ function createTraceable(ctx: Context, value: any, tracker: Tracker, noTrap?: bo
       }
     },
     set: (target, prop, value, receiver) => {
+      if (prop === symbols.original) return false
       if (prop === tracker.property) return false
       if (typeof prop === 'symbol') {
         return Reflect.set(target, prop, value, receiver)
diff --git a/packages/loader/src/inject.ts b/packages/loader/src/inject.ts
index 925cace..84001fa 100644
--- a/packages/loader/src/inject.ts
+++ b/packages/loader/src/inject.ts
@@ -1,28 +1,18 @@
 import { Context, EffectScope, Inject } from '@cordisjs/core'
+import { filterKeys } from 'cosmokit'
 import { Entry } from './entry.ts'
 
 declare module './entry.ts' {
   interface EntryOptions {
-    inject?: string[] | Inject | null
+    inject?: Inject | null
   }
 }
 
 export const name = 'inject'
 
 export function apply(ctx: Context) {
-  function getRequired(entry?: Entry) {
-    return Array.isArray(entry?.options.inject)
-      ? entry.options.inject
-      : entry?.options.inject?.required ?? []
-  }
-
-  function getInject(entry?: Entry) {
-    return Array.isArray(entry?.options.inject)
-      ? entry?.options.inject
-      : [
-        ...entry?.options.inject?.required ?? [],
-        ...entry?.options.inject?.optional ?? [],
-      ]
+  function getRequired(entry: Entry) {
+    return filterKeys(Inject.resolve(entry.options.inject), (_, meta) => meta.required)
   }
 
   const checkInject = (scope: EffectScope, name: string) => {
@@ -30,7 +20,7 @@ export function apply(ctx: Context) {
     if (scope.runtime === scope) {
       return scope.runtime.children.every(fork => checkInject(fork, name))
     }
-    if (getInject(scope.entry).includes(name)) return true
+    if (name in Inject.resolve(scope.entry?.options.inject)) return true
     return checkInject(scope.parent.scope, name)
   }
 
@@ -39,21 +29,21 @@ export function apply(ctx: Context) {
   })
 
   ctx.on('loader/entry-check', (entry) => {
-    for (const name of getRequired(entry)) {
+    for (const name in getRequired(entry)) {
       if (!entry.ctx.get(name)) return true
     }
   })
 
   ctx.on('internal/before-service', (name) => {
     for (const entry of ctx.loader.entries()) {
-      if (!getRequired(entry).includes(name)) continue
+      if (!(name in getRequired(entry))) continue
       entry.refresh()
     }
   }, { global: true })
 
   ctx.on('internal/service', (name) => {
     for (const entry of ctx.loader.entries()) {
-      if (!getRequired(entry).includes(name)) continue
+      if (!(name in getRequired(entry))) continue
       entry.refresh()
     }
   }, { global: true })
diff --git a/packages/loader/src/loader.ts b/packages/loader/src/loader.ts
index 32242b0..82210bc 100644
--- a/packages/loader/src/loader.ts
+++ b/packages/loader/src/loader.ts
@@ -50,11 +50,9 @@ export namespace Loader {
 export abstract class Loader<C extends Context = Context> extends ImportTree<C> {
   // TODO auto inject optional when provided?
   static inject = {
-    optional: ['loader'],
+    loader: { required: false },
   }
 
-  private [Context.current]!: C
-
   // process
   public envData = process.env.CORDIS_SHARED
     ? JSON.parse(process.env.CORDIS_SHARED)
@@ -127,7 +125,7 @@ export abstract class Loader<C extends Context = Context> extends ImportTree<C>
     await super.start()
   }
 
-  locate(ctx = this[Context.current]) {
+  locate(ctx = this.ctx) {
     return this._locate(ctx.scope).map(entry => entry.id)
   }
 
diff --git a/packages/schema/src/index.ts b/packages/schema/src/index.ts
index b328150..8d7c992 100644
--- a/packages/schema/src/index.ts
+++ b/packages/schema/src/index.ts
@@ -1,4 +1,4 @@
-import { Dict, remove } from 'cosmokit'
+import { defineProperty, remove } from 'cosmokit'
 import { Context, Service } from '@cordisjs/core'
 import Schema from 'schemastery'
 
@@ -7,51 +7,39 @@ export { default as Schema, default as z } from 'schemastery'
 const kSchemaOrder = Symbol('cordis.schema.order')
 
 declare module '@cordisjs/core' {
-  interface Context {
-    schema: SchemaService
-  }
-
   interface Events {
-    'internal/schema'(name: string): void
+    'internal/service-schema'(): void
   }
 }
 
-export class SchemaService extends Service {
-  _data: Dict<Schema> = Object.create(null)
+export class SchemaService {
+  _data = Schema.intersect([]) as Schema & { list: Schema[] }
 
   constructor(public ctx: Context) {
-    super(ctx, 'schema', true)
+    defineProperty(this, Service.tracker, {
+      property: 'ctx',
+    })
   }
 
-  extend(name: string, schema: Schema, order = 0) {
-    const caller = this[Context.current]
-    const target = this.get(name)
-    const index = target.list.findIndex(a => a[kSchemaOrder] < order)
+  extend(schema: Schema, order = 0) {
+    const index = this._data.list.findIndex(a => a[kSchemaOrder] < order)
     schema[kSchemaOrder] = order
-    if (index >= 0) {
-      target.list.splice(index, 0, schema)
-    } else {
-      target.list.push(schema)
-    }
-    this.ctx.emit('internal/schema', name)
-    caller.on('dispose', () => {
-      remove(target.list, schema)
-      this.ctx.emit('internal/schema', name)
+    return this.ctx.effect(() => {
+      if (index >= 0) {
+        this._data.list.splice(index, 0, schema)
+      } else {
+        this._data.list.push(schema)
+      }
+      this.ctx.emit('internal/service-schema')
+      return () => {
+        remove(this._data.list, schema)
+        this.ctx.emit('internal/service-schema')
+      }
     })
   }
 
-  get(name: string) {
-    return (this._data[name] ||= Schema.intersect([])) as Schema & { list: Schema[] }
-  }
-
-  set(name: string, schema: Schema) {
-    const caller = this[Context.current]
-    this._data[name] = schema
-    this.ctx.emit('internal/schema', name)
-    caller?.on('dispose', () => {
-      delete this._data[name]
-      this.ctx.emit('internal/schema', name)
-    })
+  toJSON() {
+    return this._data.toJSON()
   }
 }