diff --git a/packages/core/src/command.ts b/packages/core/src/command/command.ts
similarity index 87%
rename from packages/core/src/command.ts
rename to packages/core/src/command/command.ts
index 5e53219b4a..bf153034db 100644
--- a/packages/core/src/command.ts
+++ b/packages/core/src/command/command.ts
@@ -1,9 +1,10 @@
-import { Awaitable, coerce, Dict, Logger, remove, Schema } from '@koishijs/utils'
+import { coerce, Dict, Logger, remove, Schema } from '@koishijs/utils'
+import { Awaitable } from 'cosmokit'
+import { Context, Disposable } from 'cordis'
 import { Argv } from './parser'
-import { Context, Disposable, Next } from './context'
-import { Channel, User } from './database'
-import { Computed, FieldCollector, Session } from './session'
-import * as internal from './internal'
+import { Next } from '../protocol'
+import { Channel, User } from '../database'
+import { Computed, FieldCollector, Session } from '../protocol/session'
 
 const logger = new Logger('command')
 
@@ -11,6 +12,9 @@ export type Extend<O extends {}, K extends string, T> = {
   [P in K | keyof O]?: (P extends keyof O ? O[P] : unknown) & (P extends K ? T : unknown)
 }
 
+export interface CommandService {
+}
+
 export namespace Command {
   export interface Shortcut {
     name?: string | RegExp
@@ -43,11 +47,9 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
   private _channelFields: FieldCollector<'channel'>[] = [['locale']]
   private _actions: Command.Action[] = []
   private _checkers: Command.Action[] = [async (argv) => {
-    return this.app.serial(argv.session, 'command/before-execute', argv)
+    return this.ctx.serial(argv.session, 'command/before-execute', argv)
   }]
 
-  public static enableHelp: typeof internal.enableHelp
-
   static defaultConfig: Command.Config = {
     authority: 1,
     showWarning: true,
@@ -72,15 +74,11 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
     return this
   }
 
-  constructor(name: string, decl: string, context: Context) {
-    super(name, decl, context)
+  constructor(name: string, decl: string, ctx: Context) {
+    super(name, decl, ctx)
     this.config = { ...Command.defaultConfig }
     this._registerAlias(name)
-    context.app._commandList.push(this)
-  }
-
-  get app() {
-    return this.context.app
+    ctx.$commander._commandList.push(this)
   }
 
   get displayName() {
@@ -109,9 +107,9 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
     }
 
     // register global
-    const previous = this.app.getCommand(name)
+    const previous = this.ctx.$commander.getCommand(name)
     if (!previous) {
-      this.app._commands.set(name, this)
+      this.ctx.$commander._commands.set(name, this)
     } else if (previous !== this) {
       throw new Error(`duplicate command names: "${name}"`)
     }
@@ -119,7 +117,7 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
     // add disposable
     this._disposables?.push(() => {
       remove(this._aliases, name)
-      this.app._commands.delete(name)
+      this.ctx.$commander._commands.delete(name)
     })
   }
 
@@ -149,8 +147,8 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
     if (this._disposed) return this
     config.name = name
     config.command = this
-    this.app._shortcuts.push(config)
-    this._disposables?.push(() => remove(this.app._shortcuts, config))
+    this.ctx.$commander._shortcuts.push(config)
+    this._disposables?.push(() => remove(this.ctx.$commander._shortcuts, config))
     return this
   }
 
@@ -161,7 +159,7 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
     const desc = typeof args[0] === 'string' ? args.shift() as string : ''
     const config = args[0] as Command.Config || {}
     if (this._disposed) config.patch = true
-    return this.context.command(def, desc, config)
+    return this.ctx.command(def, desc, config)
   }
 
   usage(text: Command.Usage<U, G>) {
@@ -191,7 +189,7 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
 
   match(session: Session) {
     const { authority = Infinity } = (session.user || {}) as User
-    return this.context.match(session) && this.config.authority <= authority
+    return this.ctx.match(session) && this.config.authority <= authority
   }
 
   getConfig<K extends keyof Command.Config>(key: K, session: Session): Exclude<Command.Config[K], (session: Session) => any> {
@@ -269,7 +267,7 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
       if (index === length) throw error
       const stack = coerce(error)
       logger.warn(`${argv.source ||= this.stringify(args, options)}\n${stack}`)
-      this.app.emit(argv.session, 'command-error', argv, error)
+      this.ctx.emit(argv.session, 'command-error', argv, error)
     }
 
     return ''
@@ -277,13 +275,13 @@ export class Command<U extends User.Field = never, G extends Channel.Field = nev
 
   dispose() {
     this._disposed = true
-    this.app.emit('command-removed', this)
+    this.ctx.emit('command-removed', this)
     for (const cmd of this.children.slice()) {
       cmd.dispose()
     }
-    this.app._shortcuts = this.app._shortcuts.filter(s => s.command !== this)
-    this._aliases.forEach(name => this.app._commands.delete(name))
-    remove(this.app._commandList, this)
+    this.ctx.$commander._shortcuts = this.ctx.$commander._shortcuts.filter(s => s.command !== this)
+    this._aliases.forEach(name => this.ctx.$commander._commands.delete(name))
+    remove(this.ctx.$commander._commandList, this)
     if (this.parent) {
       remove(this.parent.children, this)
     }
diff --git a/packages/core/src/internal/help.ts b/packages/core/src/command/help.ts
similarity index 90%
rename from packages/core/src/internal/help.ts
rename to packages/core/src/command/help.ts
index e965f7123a..aac8dbfd15 100644
--- a/packages/core/src/internal/help.ts
+++ b/packages/core/src/command/help.ts
@@ -1,8 +1,8 @@
-import { Argv } from '../parser'
-import { Command } from '../command'
-import { Context } from '../context'
+import { Argv } from './parser'
+import { Command } from './command'
+import { Context } from 'cordis'
 import { Channel, Tables, User } from '../database'
-import { FieldCollector, Session } from '../session'
+import { FieldCollector, Session } from '../protocol/session'
 
 interface HelpOptions {
   showHidden?: boolean
@@ -27,11 +27,11 @@ export default function help(ctx: Context, config: HelpConfig = {}) {
     ctx.on('command-added', cmd => cmd.use(enableHelp))
   }
 
-  const app = ctx.app
+  const $ = ctx.$commander
   function findCommand(target: string) {
-    const command = app._commands.resolve(target)
+    const command = $._commands.resolve(target)
     if (command) return command
-    const shortcut = app._shortcuts.find(({ name }) => {
+    const shortcut = $._shortcuts.find(({ name }) => {
       return typeof name === 'string' ? name === target : name.test(target)
     })
     if (shortcut) return shortcut.command
@@ -44,7 +44,7 @@ export default function help(ctx: Context, config: HelpConfig = {}) {
     session.collect(key, { ...argv, command, args: [], options: { help: true } }, fields)
   }
 
-  const cmd = ctx.command('help [command:string]', { authority: 0, ...config })
+  const cmd = $.command('help [command:string]', { authority: 0, ...config })
     .userFields(['authority'])
     .userFields(createCollector('user'))
     .channelFields(createCollector('channel'))
@@ -52,7 +52,7 @@ export default function help(ctx: Context, config: HelpConfig = {}) {
     .option('showHidden', '-H')
     .action(async ({ session, options }, target) => {
       if (!target) {
-        const commands = app._commandList.filter(cmd => cmd.parent === null)
+        const commands = $._commandList.filter(cmd => cmd.parent === null)
         const output = formatCommands('.global-prolog', session, commands, options)
         const epilog = session.text('.global-epilog')
         if (epilog) output.push(epilog)
@@ -60,14 +60,14 @@ export default function help(ctx: Context, config: HelpConfig = {}) {
       }
 
       const command = findCommand(target)
-      if (!command?.context.match(session)) {
+      if (!command?.ctx.match(session)) {
         return session.suggest({
           target,
           items: getCommandNames(session),
           prefix: session.text('suggest.help-prefix'),
           suffix: session.text('suggest.help-suffix'),
           async apply(suggestion) {
-            return showHelp(ctx.getCommand(suggestion), this as any, options)
+            return showHelp($.getCommand(suggestion), this as any, options)
           },
         })
       }
@@ -79,7 +79,7 @@ export default function help(ctx: Context, config: HelpConfig = {}) {
 }
 
 export function getCommandNames(session: Session) {
-  return session.app._commandList
+  return session.app.$commander._commandList
     .filter(cmd => cmd.match(session) && !cmd.config.hidden)
     .flatMap(cmd => cmd._aliases)
 }
@@ -141,13 +141,13 @@ function getOptions(command: Command, session: Session<'authority'>, config: Hel
     let line = `${authority}${option.syntax}`
     const description = session.text(option.descPath ?? [`commands.${command.name}.options.${option.name}`, ''])
     if (description) line += '  ' + description
-    line = command.app.chain('help/option', line, option, command, session)
+    line = command.ctx.chain('help/option', line, option, command, session)
     output.push('    ' + line)
     for (const value in option.valuesSyntax) {
       let line = `${authority}${option.valuesSyntax[value]}`
       const description = session.text([`commands.${command.name}.options.${option.name}.${value}`, ''])
       if (description) line += '  ' + description
-      line = command.app.chain('help/option', line, option, command, session)
+      line = command.ctx.chain('help/option', line, option, command, session)
       output.push('    ' + line)
     }
   })
diff --git a/packages/core/src/command/index.ts b/packages/core/src/command/index.ts
new file mode 100644
index 0000000000..a64714a364
--- /dev/null
+++ b/packages/core/src/command/index.ts
@@ -0,0 +1,139 @@
+import { Context } from 'cordis'
+import { Awaitable } from 'cosmokit'
+import { Command } from './command'
+import { Argv } from './parser'
+import runtime from './runtime'
+import validate from './validate'
+import help, { HelpConfig } from './help'
+import { Channel, User } from '../database'
+import { Session } from '../protocol'
+
+export * from './command'
+export * from './help'
+export * from './runtime'
+export * from './parser'
+export * from './validate'
+
+interface CommandMap extends Map<string, Command> {
+  resolve(key: string): Command
+}
+
+declare module 'cordis' {
+  interface Context extends Commander.Delegates {
+    $commander: Commander
+  }
+
+  interface Events {
+    'before-parse'(content: string, session: Session): Argv
+    'command-added'(command: Command): void
+    'command-removed'(command: Command): void
+    'command-error'(argv: Argv, error: any): void
+    'command/before-execute'(argv: Argv): Awaitable<void | string>
+    'command/before-attach-channel'(argv: Argv, fields: Set<Channel.Field>): void
+    'command/before-attach-user'(argv: Argv, fields: Set<User.Field>): void
+    'help/command'(output: string[], command: Command, session: Session): void
+    'help/option'(output: string, option: Argv.OptionDeclaration, command: Command, session: Session): string
+  }
+}
+
+export namespace Commander {
+  export interface Config {
+    help?: false | HelpConfig
+  }
+
+  export interface Delegates {
+    command<D extends string>(def: D, config?: Command.Config): Command<never, never, Argv.ArgumentType<D>>
+    command<D extends string>(def: D, desc: string, config?: Command.Config): Command<never, never, Argv.ArgumentType<D>>
+  }
+}
+
+export class Commander {
+  static readonly key = '$commander'
+
+  _commandList: Command[] = []
+  _commands = new Map<string, Command>() as CommandMap
+  _shortcuts: Command.Shortcut[] = []
+
+  constructor(private ctx: Context, private config: Commander.Config = {}) {
+    ctx.plugin(runtime)
+    ctx.plugin(validate)
+    ctx.plugin(help, config.help)
+  }
+
+  protected get caller(): Context {
+    return this[Context.current] || this.ctx
+  }
+
+  resolve(key: string) {
+    if (!key) return
+    const segments = key.split('.')
+    let i = 1, name = segments[0], cmd: Command
+    while ((cmd = this.getCommand(name)) && i < segments.length) {
+      name = cmd.name + '.' + segments[i++]
+    }
+    return cmd
+  }
+
+  getCommand(name: string) {
+    return this._commands.get(name)
+  }
+
+  command(def: string, ...args: [Command.Config?] | [string, Command.Config?]) {
+    const desc = typeof args[0] === 'string' ? args.shift() as string : ''
+    const config = args[0] as Command.Config
+    const path = def.split(' ', 1)[0].toLowerCase()
+    const decl = def.slice(path.length)
+    const segments = path.split(/(?=[./])/g)
+
+    let parent: Command, root: Command
+    const list: Command[] = []
+    segments.forEach((segment, index) => {
+      const code = segment.charCodeAt(0)
+      const name = code === 46 ? parent.name + segment : code === 47 ? segment.slice(1) : segment
+      let command = this.getCommand(name)
+      if (command) {
+        if (parent) {
+          if (command === parent) {
+            throw new Error(`cannot set a command (${command.name}) as its own subcommand`)
+          }
+          if (command.parent) {
+            if (command.parent !== parent) {
+              throw new Error(`cannot create subcommand ${path}: ${command.parent.name}/${command.name} already exists`)
+            }
+          } else {
+            command.parent = parent
+            parent.children.push(command)
+          }
+        }
+        return parent = command
+      }
+      command = new Command(name, decl, this.caller)
+      list.push(command)
+      if (!root) root = command
+      if (parent) {
+        command.parent = parent
+        command.config.authority = parent.config.authority
+        parent.children.push(command)
+      }
+      parent = command
+    })
+
+    if (desc) this.caller.i18n.define('', `commands.${parent.name}.description`, desc)
+    Object.assign(parent.config, config)
+    list.forEach(command => this.caller.emit('command-added', command))
+    if (!config?.patch) {
+      if (root) this.caller.state.disposables.unshift(() => root.dispose())
+      return parent
+    }
+
+    if (root) root.dispose()
+    const command = Object.create(parent)
+    command._disposables = this.caller.state.disposables
+    return command
+  }
+}
+
+Context.service(Commander.key, {
+  constructor: Commander,
+  methods: ['command'],
+})
diff --git a/packages/core/src/parser.ts b/packages/core/src/command/parser.ts
similarity index 98%
rename from packages/core/src/parser.ts
rename to packages/core/src/command/parser.ts
index b11abe3b33..7db42f8c6a 100644
--- a/packages/core/src/parser.ts
+++ b/packages/core/src/command/parser.ts
@@ -1,8 +1,9 @@
 import { camelCase, Dict, escapeRegExp, paramCase, segment, Time } from '@koishijs/utils'
 import { Command } from './command'
-import { Context, Next } from './context'
-import { Channel, User } from './database'
-import { Session } from './session'
+import { Context } from 'cordis'
+import { Channel, User } from '../database'
+import { Session } from '../protocol/session'
+import { Next } from '../protocol'
 
 export interface Token {
   rest?: string
@@ -379,7 +380,7 @@ export namespace Argv {
     private _namedOptions: OptionDeclarationMap = {}
     private _symbolicOptions: OptionDeclarationMap = {}
 
-    constructor(public readonly name: string, declaration: string, public context: Context) {
+    constructor(public readonly name: string, declaration: string, public ctx: Context) {
       if (!name) throw new Error('expect a command name')
       const decl = this._arguments = parseDecl(declaration)
       this.declaration = decl.stripped
@@ -434,7 +435,7 @@ export namespace Argv {
       }
 
       if (desc) {
-        this.context.i18n.define('', path, desc)
+        this.ctx.i18n.define('', path, desc)
       }
 
       this._assignOption(option, names, this._namedOptions)
diff --git a/packages/core/src/internal/runtime.ts b/packages/core/src/command/runtime.ts
similarity index 89%
rename from packages/core/src/internal/runtime.ts
rename to packages/core/src/command/runtime.ts
index e05773cb29..58b0bf599b 100644
--- a/packages/core/src/internal/runtime.ts
+++ b/packages/core/src/command/runtime.ts
@@ -1,7 +1,7 @@
 import { defineProperty, valueMap } from '@koishijs/utils'
-import { Argv } from '../parser'
-import { Context } from '../context'
-import { Session } from '../session'
+import { Argv } from './parser'
+import { Context } from 'cordis'
+import { Session } from '../protocol/session'
 
 export default function runtime(ctx: Context) {
   ctx.before('parse', (content, session) => {
@@ -20,9 +20,9 @@ export default function runtime(ctx: Context) {
   ctx.before('parse', (content, session) => {
     const { parsed, quote } = session
     if (parsed.prefix || quote) return
-    for (const shortcut of ctx.app._shortcuts) {
+    for (const shortcut of ctx.$commander._shortcuts) {
       const { name, fuzzy, command, prefix, options = {}, args = [] } = shortcut
-      if (prefix && !parsed.appel || !command.context.match(session)) continue
+      if (prefix && !parsed.appel || !command.ctx.match(session)) continue
       if (typeof name === 'string') {
         if (!fuzzy && content !== name || !content.startsWith(name)) continue
         const message = content.slice(name.length)
@@ -66,7 +66,7 @@ export default function runtime(ctx: Context) {
   })
 
   function executeHelp(session: Session, name: string) {
-    if (!ctx.getCommand('help')) return
+    if (!ctx.$commander.getCommand('help')) return
     return session.execute({
       name: 'help',
       args: [name],
@@ -82,7 +82,7 @@ export default function runtime(ctx: Context) {
     if (command['_actions'].length) return
     // subcommand redirect
     const arg0 = args.shift() || ''
-    const subcommand = ctx.getCommand(command.name + '.' + arg0)
+    const subcommand = ctx.$commander.getCommand(command.name + '.' + arg0)
     if (subcommand) {
       // save command names
       const commands = session['__redirected_commands'] ||= [
diff --git a/packages/core/src/internal/validate.ts b/packages/core/src/command/validate.ts
similarity index 97%
rename from packages/core/src/internal/validate.ts
rename to packages/core/src/command/validate.ts
index 3aff7a7e9e..51d87b7c04 100644
--- a/packages/core/src/internal/validate.ts
+++ b/packages/core/src/command/validate.ts
@@ -1,5 +1,5 @@
-import { Argv } from '../parser'
-import { Context } from '../context'
+import { Argv } from './parser'
+import { Context } from 'cordis'
 
 export default function validate(ctx: Context) {
   // add user fields