diff --git a/packages/core/src/context.ts b/packages/core/src/context.ts
index 9de0b29..a327f0f 100644
--- a/packages/core/src/context.ts
+++ b/packages/core/src/context.ts
@@ -254,6 +254,7 @@ export class Context {
     return dispose
   }
 
+  /** @deprecated use `ctx.set()` instead */
   provide(name: string, value?: any, builtin?: boolean) {
     const internal = Context.ensureInternal.call(this.root)
     if (name in internal) return
diff --git a/packages/core/src/events.ts b/packages/core/src/events.ts
index e224727..e115049 100644
--- a/packages/core/src/events.ts
+++ b/packages/core/src/events.ts
@@ -45,8 +45,8 @@ export class Lifecycle {
   _tasks = new Set<Promise<void>>()
   _hooks: Record<keyof any, Hook[]> = {}
 
-  constructor(private root: Context) {
-    defineProperty(this, Context.origin, root)
+  constructor(private ctx: Context) {
+    defineProperty(this, Context.origin, ctx)
 
     defineProperty(this.on('internal/listener', function (this: Context, name, listener, options: EventOptions) {
       const method = options.prepend ? 'unshift' : 'push'
@@ -62,14 +62,14 @@ export class Lifecycle {
         this.scope.runtime.forkables[method](listener as any)
         return this.scope.collect('event <fork>', () => remove(this.scope.runtime.forkables, listener))
       }
-    }), Context.static, root.scope)
+    }), Context.static, ctx.scope)
 
     for (const level of ['info', 'error', 'warning']) {
       defineProperty(this.on(`internal/${level}`, (format, ...param) => {
         if (this._hooks[`internal/${level}`].length > 1) return
         // eslint-disable-next-line no-console
         console.info(format, ...param)
-      }), Context.static, root.scope)
+      }), Context.static, ctx.scope)
     }
 
     // non-reusable plugin forks are not responsive to isolated service changes
@@ -83,7 +83,7 @@ export class Lifecycle {
           scope.reset()
         }
       }
-    }, { global: true }), Context.static, root.scope)
+    }, { global: true }), Context.static, ctx.scope)
 
     defineProperty(this.on('internal/service', function (this: Context, name) {
       for (const runtime of this.registry.values()) {
@@ -94,7 +94,7 @@ export class Lifecycle {
           scope.start()
         }
       }
-    }, { global: true }), Context.static, root.scope)
+    }, { global: true }), Context.static, ctx.scope)
 
     // inject in ancestor contexts
     defineProperty(this.on('internal/inject', function (name) {
@@ -105,7 +105,7 @@ export class Lifecycle {
         }
         parent = parent.scope.parent
       }
-    }, { global: true }), Context.static, root.scope)
+    }, { global: true }), Context.static, ctx.scope)
   }
 
   async flush() {
@@ -128,7 +128,7 @@ export class Lifecycle {
     if (name !== 'internal/event') {
       this.emit('internal/event', type, name, args, thisArg)
     }
-    return [this.getHooks(name, thisArg), thisArg ?? this[Context.origin]] as const
+    return [this.getHooks(name, thisArg), thisArg ?? this.ctx] as const
   }
 
   async parallel(...args: any[]) {
@@ -162,10 +162,9 @@ export class Lifecycle {
   }
 
   register(label: string, hooks: Hook[], listener: any, options: EventOptions) {
-    const caller = this[Context.origin]
     const method = options.prepend ? 'unshift' : 'push'
-    hooks[method]([caller, listener, options])
-    return caller.state.collect(label, () => this.unregister(hooks, listener))
+    hooks[method]([this.ctx, listener, options])
+    return this.ctx.state.collect(label, () => this.unregister(hooks, listener))
   }
 
   unregister(hooks: Hook[], listener: any) {
@@ -182,9 +181,8 @@ export class Lifecycle {
     }
 
     // handle special events
-    const caller: Context = this[Context.origin]
-    caller.scope.assertActive()
-    const result = this.bail(caller, 'internal/listener', name, listener, options)
+    this.ctx.scope.assertActive()
+    const result = this.bail(this.ctx, 'internal/listener', name, listener, options)
     if (result) return result
 
     const hooks = this._hooks[name] ||= []
@@ -217,7 +215,7 @@ export class Lifecycle {
   async stop() {
     this.isActive = false
     // `dispose` event is handled by state.disposables
-    this.root.scope.reset()
+    this.ctx.scope.reset()
   }
 }
 
diff --git a/packages/core/src/registry.ts b/packages/core/src/registry.ts
index e672e68..0c363b5 100644
--- a/packages/core/src/registry.ts
+++ b/packages/core/src/registry.ts
@@ -65,10 +65,10 @@ export class Registry<C extends Context = Context> {
   private _counter = 0
   private _internal = new Map<Function, MainScope<C>>()
 
-  constructor(private root: Context, config: any) {
-    defineProperty(this, Context.origin, root)
-    root.scope = new MainScope(this, null!, config)
-    root.scope.runtime.isReactive = true
+  constructor(private ctx: Context, config: any) {
+    defineProperty(this, Context.origin, ctx)
+    ctx.scope = new MainScope(this, null!, config)
+    ctx.scope.runtime.isReactive = true
   }
 
   get counter() {
@@ -139,7 +139,7 @@ export class Registry<C extends Context = Context> {
     // check if it's a valid plugin
     this.resolve(plugin, true)
 
-    const context: Context = this[Context.origin]
+    const context: Context = this.ctx
     context.scope.assertActive()
 
     // resolve plugin config
diff --git a/packages/core/src/service.ts b/packages/core/src/service.ts
index b183f7c..73a1dfc 100644
--- a/packages/core/src/service.ts
+++ b/packages/core/src/service.ts
@@ -79,14 +79,13 @@ export abstract class Service<T = unknown, C extends Context = Context> {
   }
 
   protected [symbols.extend](props?: any) {
-    const caller = this[symbols.origin]
     let self: any
     if (this[Service.invoke]) {
       self = createCallable(this.name, this)
     } else {
       self = Object.create(this)
     }
-    defineProperty(self, symbols.origin, caller)
+    defineProperty(self, symbols.origin, this.ctx)
     return Context.associate<this>(Object.assign(self, props), this.name)
   }
 
diff --git a/packages/core/src/utils.ts b/packages/core/src/utils.ts
index 62c49a8..540d7e7 100644
--- a/packages/core/src/utils.ts
+++ b/packages/core/src/utils.ts
@@ -57,7 +57,7 @@ export function joinPrototype(proto1: {}, proto2: {}) {
 export function createTraceable(ctx: any, value: any) {
   const proxy = new Proxy(value, {
     get: (target, name, receiver) => {
-      if (name === symbols.origin) return ctx
+      if (name === symbols.origin || name === 'ctx') return ctx
       return Reflect.get(target, name, receiver)
     },
     apply: (target, thisArg, args) => {
diff --git a/packages/core/tests/dispose.spec.ts b/packages/core/tests/dispose.spec.ts
index 67b7941..4617f3e 100644
--- a/packages/core/tests/dispose.spec.ts
+++ b/packages/core/tests/dispose.spec.ts
@@ -75,7 +75,7 @@ describe('Disposables', () => {
     expect(dispose.mock.calls).to.have.length(1)
   })
 
-  it('dispose event', async () => {
+  it('dispose event error', async () => {
     const root = new Context()
     const error = mock.fn()
     const dispose = mock.fn(() => {
diff --git a/packages/core/tests/invoke.spec.ts b/packages/core/tests/invoke.spec.ts
new file mode 100644
index 0000000..87e2774
--- /dev/null
+++ b/packages/core/tests/invoke.spec.ts
@@ -0,0 +1,61 @@
+import { expect } from 'chai'
+import { Context, Service } from '../src'
+
+describe('functional service', () => {
+  it('functional service', async () => {
+    interface Config {}
+
+    interface Foo {
+      (init?: Config): Config
+    }
+
+    class Foo extends Service<Config> {
+      static [Service.provide] = 'foo'
+      static [Service.immediate] = true
+
+      protected [Service.invoke](init?: Config) {
+        const caller = this[Context.origin]
+        expect(caller).to.be.instanceof(Context)
+        let result = { ...this.config }
+        let intercept = caller[Context.intercept]
+        while (intercept) {
+          Object.assign(result, intercept.foo)
+          intercept = Object.getPrototypeOf(intercept)
+        }
+        Object.assign(result, init)
+        return result
+      }
+
+      reflect() {
+        return this()
+      }
+
+      extend(config?: Config) {
+        return this[Service.extend]({
+          config: { ...this.config, ...config },
+        })
+      }
+    }
+
+    const root = new Context()
+    root.plugin(Foo, { a: 1 })
+
+    // access from context
+    expect(root.foo()).to.deep.equal({ a: 1 })
+    const ctx1 = root.intercept('foo', { b: 2 })
+    expect(ctx1.foo()).to.deep.equal({ a: 1, b: 2 })
+    const foo1 = ctx1.foo
+    expect(foo1).to.be.instanceof(Foo)
+
+    // create extension
+    const foo2 = root.foo.extend({ c: 3 })
+    expect(foo2).to.be.instanceof(Foo)
+    expect(foo2()).to.deep.equal({ a: 1, c: 3 })
+    const foo3 = foo1.extend({ d: 4 })
+    expect(foo3).to.be.instanceof(Foo)
+    expect(foo3.reflect()).to.deep.equal({ a: 1, b: 2, d: 4 })
+
+    // context tracibility
+    expect(foo1.reflect()).to.deep.equal({ a: 1, b: 2 })
+  })
+})
diff --git a/packages/core/tests/service.spec.ts b/packages/core/tests/service.spec.ts
index 02aba5a..009944e 100644
--- a/packages/core/tests/service.spec.ts
+++ b/packages/core/tests/service.spec.ts
@@ -128,19 +128,34 @@ describe('Service', () => {
     expect(callback.mock.calls).to.have.length(1)
   })
 
-  it('Context.origin', async () => {
+  it('traceable effect', async () => {
     class Foo extends Service {
+      size = 0
+
       constructor(ctx: Context) {
         super(ctx, 'foo', true)
       }
+
+      increse() {
+        return this.ctx.effect(() => {
+          this.size++
+          return () => this.size--
+        })
+      }
     }
 
     const root = new Context()
     root.plugin(Foo)
-    expect(root.foo[Context.origin]).to.equal(root)
+    root.foo.increse()
+    expect(root.foo.size).to.equal(1)
+
+    const fork = root.plugin((ctx) => {
+      ctx.foo.increse()
+      expect(ctx.foo.size).to.equal(2)
+    })
 
-    const ctx = root.extend()
-    expect(ctx.foo[Context.origin]).to.equal(ctx)
+    fork.dispose()
+    expect(root.foo.size).to.equal(1)
   })
 
   it('dependency update', async () => {
@@ -279,61 +294,4 @@ describe('Service', () => {
     expect(bar.mock.calls).to.have.length(1)
     expect(qux.mock.calls).to.have.length(1)
   })
-
-  it('functional service', async () => {
-    interface Config {}
-
-    interface Foo {
-      (init?: Config): Config
-    }
-
-    class Foo extends Service<Config> {
-      static [Service.provide] = 'foo'
-      static [Service.immediate] = true
-
-      protected [Service.invoke](init?: Config) {
-        const caller = this[Context.origin]
-        expect(caller).to.be.instanceof(Context)
-        let result = { ...this.config }
-        let intercept = caller[Context.intercept]
-        while (intercept) {
-          Object.assign(result, intercept.foo)
-          intercept = Object.getPrototypeOf(intercept)
-        }
-        Object.assign(result, init)
-        return result
-      }
-
-      reflect() {
-        return this()
-      }
-
-      extend(config?: Config) {
-        return this[Service.extend]({
-          config: { ...this.config, ...config },
-        })
-      }
-    }
-
-    const root = new Context()
-    root.plugin(Foo, { a: 1 })
-
-    // access from context
-    expect(root.foo()).to.deep.equal({ a: 1 })
-    const ctx1 = root.intercept('foo', { b: 2 })
-    expect(ctx1.foo()).to.deep.equal({ a: 1, b: 2 })
-    const foo1 = ctx1.foo
-    expect(foo1).to.be.instanceof(Foo)
-
-    // create extension
-    const foo2 = root.foo.extend({ c: 3 })
-    expect(foo2).to.be.instanceof(Foo)
-    expect(foo2()).to.deep.equal({ a: 1, c: 3 })
-    const foo3 = foo1.extend({ d: 4 })
-    expect(foo3).to.be.instanceof(Foo)
-    expect(foo3.reflect()).to.deep.equal({ a: 1, b: 2, d: 4 })
-
-    // context tracibility
-    expect(foo1.reflect()).to.deep.equal({ a: 1, b: 2 })
-  })
 })