diff --git a/packages/core/src/adapter.ts b/packages/core/src/adapter.ts
index a017f132..4104daa2 100644
--- a/packages/core/src/adapter.ts
+++ b/packages/core/src/adapter.ts
@@ -23,9 +23,9 @@ export abstract class Adapter<C extends Context = Context, B extends Bot<C> = Bo
 
 export namespace Adapter {
   export interface WsClientConfig {
-    retryLazy?: number
-    retryTimes?: number
-    retryInterval?: number
+    retryLazy: number
+    retryTimes: number
+    retryInterval: number
   }
 
   export const WsClientConfig: z<WsClientConfig> = z.object({
@@ -35,7 +35,7 @@ export namespace Adapter {
   }).description('连接设置')
 
   export abstract class WsClientBase<C extends Context, B extends Bot<C>> extends Adapter<C, B> {
-    protected socket: WebSocket
+    protected socket?: WebSocket
     protected connectionId = 0
 
     protected abstract prepare(): Awaitable<WebSocket>
@@ -79,7 +79,7 @@ export namespace Adapter {
         let socket: WebSocket
         try {
           socket = await this.prepare()
-        } catch (error) {
+        } catch (error: any) {
           reconnect(initial, error.toString() || `failed to prepare websocket`)
           return
         }
@@ -92,7 +92,7 @@ export namespace Adapter {
         })
 
         socket.addEventListener('close', ({ code, reason }) => {
-          if (this.socket === socket) this.socket = null
+          if (this.socket === socket) this.socket = undefined
           logger.debug(`websocket closed with ${code}`)
           reconnect(initial, reason.toString() || `failed to connect to ${url}, code: ${code}`)
         })
@@ -125,7 +125,7 @@ export namespace Adapter {
       return this.bot.isActive
     }
 
-    setStatus(status: Status, error: Error = null) {
+    setStatus(status: Status, error?: Error) {
       this.bot.status = status
       this.bot.error = error
     }
diff --git a/packages/core/src/bot.ts b/packages/core/src/bot.ts
index 6da49832..907c07a8 100644
--- a/packages/core/src/bot.ts
+++ b/packages/core/src/bot.ts
@@ -37,7 +37,7 @@ export abstract class Bot<C extends Context = Context, T = any> {
   public platform: string
   public features: string[]
   public adapter?: Adapter<C, this>
-  public error?: Error
+  public error: any
   public callbacks: Dict<Function> = {}
   public logger: Logger
 
@@ -131,7 +131,7 @@ export abstract class Bot<C extends Context = Context, T = any> {
 
   online() {
     this.status = Status.ONLINE
-    this.error = null
+    this.error = undefined
   }
 
   offline(error?: Error) {
@@ -145,7 +145,7 @@ export abstract class Bot<C extends Context = Context, T = any> {
     try {
       await this.context.parallel('bot-connect', this)
       await this.adapter?.connect(this)
-    } catch (error) {
+    } catch (error: any) {
       this.offline(error)
     }
   }
@@ -193,7 +193,7 @@ export abstract class Bot<C extends Context = Context, T = any> {
 
   async createMessage(channelId: string, content: h.Fragment, referrer?: any, options?: SendOptions) {
     const { MessageEncoder } = this.constructor as typeof Bot
-    return new MessageEncoder(this, channelId, referrer, options).send(content)
+    return new MessageEncoder!(this, channelId, referrer, options).send(content)
   }
 
   async sendMessage(channelId: string, content: h.Fragment, referrer?: any, options?: SendOptions) {
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index c6fadf94..7723d676 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -3,7 +3,7 @@ import { Awaitable, defineProperty, Dict } from 'cosmokit'
 import { Bot } from './bot'
 import { ExtractParams, InternalRequest, InternalRouter, JsonForm } from './internal'
 import { Session } from './session'
-import { HTTP } from '@cordisjs/plugin-http'
+import { FileResponse, HTTP } from '@cordisjs/plugin-http'
 import { Meta, Response, SendOptions } from '@satorijs/protocol'
 import h from '@satorijs/element'
 
@@ -88,7 +88,7 @@ declare module '@cordisjs/plugin-http' {
 HTTP.createConfig = function createConfig(this, endpoint) {
   return z.object({
     endpoint: z.string().role('link').description('要连接的服务器地址。')
-      .default(typeof endpoint === 'string' ? endpoint : null)
+      .default(typeof endpoint === 'string' ? endpoint : undefined!)
       .required(typeof endpoint === 'boolean' ? endpoint : false),
     headers: z.dict(String).role('table').description('要附加的额外请求头。'),
     ...this.Config.dict,
@@ -172,7 +172,7 @@ export class Satori<C extends Context = Context> extends Service<unknown, C> {
   public _loginSeq = 0
   public _sessionSeq = 0
 
-  constructor(ctx?: C) {
+  constructor(ctx: C) {
     super(ctx)
     ctx.mixin('satori', ['bots', 'component'])
 
@@ -185,12 +185,12 @@ export class Satori<C extends Context = Context> extends Service<unknown, C> {
       const { status, body, headers } = await self.handleInternalRoute('GET', url)
       if (status >= 400) throw new Error(`Failed to fetch ${_url}, status code: ${status}`)
       if (status >= 300) {
-        const location = headers?.get('location')
+        const location = headers?.get('location')!
         return this.file(location, options)
       }
       const type = headers?.get('content-type')
       const filename = headers?.get('content-disposition')?.split('filename=')[1]
-      return { data: body, filename, type, mime: type }
+      return { data: body, filename, type, mime: type } as FileResponse
     })
 
     this._internalRouter = new InternalRouter(ctx)
@@ -223,7 +223,7 @@ export class Satori<C extends Context = Context> extends Service<unknown, C> {
     })
   }
 
-  public bots = new Proxy([], {
+  public bots = new Proxy([] as Bot<C>[], {
     get(target, prop) {
       if (prop in target || typeof prop === 'symbol') {
         return Reflect.get(target, prop)
@@ -270,7 +270,7 @@ export class Satori<C extends Context = Context> extends Service<unknown, C> {
 
   toJSON(meta = false): Meta {
     return {
-      logins: meta ? undefined : this.bots.map(bot => bot.toJSON()),
+      logins: meta ? undefined! : this.bots.map(bot => bot.toJSON()),
       proxyUrls: [...this.proxyUrls],
     }
   }
diff --git a/packages/core/src/message.ts b/packages/core/src/message.ts
index 28861e20..a9fc6ebd 100644
--- a/packages/core/src/message.ts
+++ b/packages/core/src/message.ts
@@ -12,7 +12,7 @@ class AggregateError extends Error {
 export abstract class MessageEncoder<C extends Context = Context, B extends Bot<C> = Bot<C>> {
   public errors: Error[] = []
   public results: Message[] = []
-  public session: C[typeof Context.session]
+  public session!: C[typeof Context.session]
 
   constructor(public bot: B, public channelId: string, public referrer?: any, public options: SendOptions = {}) {}
 
@@ -38,7 +38,7 @@ export abstract class MessageEncoder<C extends Context = Context, B extends Bot<
     })
     for (const key in this.options.session || {}) {
       if (key === 'id' || key === 'event') continue
-      this.session[key] = this.options.session[key]
+      this.session[key] = this.options.session![key]
     }
     await this.prepare()
     const session = this.options.session ?? this.session
diff --git a/packages/core/src/session.ts b/packages/core/src/session.ts
index 1121b916..6651f36d 100644
--- a/packages/core/src/session.ts
+++ b/packages/core/src/session.ts
@@ -36,8 +36,8 @@ export class Session<C extends Context = Context> {
 
   public id: number // for backward compatibility
   public sn: number
-  public bot: Bot<C>
-  public app: C['root']
+  public bot!: Bot<C>
+  public app!: C['root']
   public event: Event
   public locales: string[] = []
 
@@ -59,21 +59,21 @@ export class Session<C extends Context = Context> {
   }
 
   get isDirect() {
-    return this.event.channel.type === Channel.Type.DIRECT
+    return this.event.channel?.type === Channel.Type.DIRECT
   }
 
   set isDirect(value) {
     (this.event.channel ??= {} as Channel).type = value ? Channel.Type.DIRECT : Channel.Type.TEXT
   }
 
-  get author(): GuildMember & User {
+  get author() {
     return {
       ...this.event.user,
       ...this.event.member,
       userId: this.event.user?.id,
       username: this.event.user?.name,
       nickname: this.event.member?.name,
-    }
+    } as GuildMember & User
   }
 
   get uid() {
@@ -114,7 +114,7 @@ export class Session<C extends Context = Context> {
     this.event.message.quote = undefined
     this.event.message.elements = isNullable(value) ? value : h.parse(value)
     if (this.event.message.elements?.[0]?.type === 'quote') {
-      const el = this.event.message.elements.shift()
+      const el = this.event.message.elements.shift()!
       this.event.message.quote = Resource.decode(el)
     }
   }
@@ -146,7 +146,7 @@ export class Session<C extends Context = Context> {
       event.message.content = this.content
       delete event.message.elements
       if (event.message.quote) {
-        event.message.content = Resource.encode('quote', event.message.quote) + event.message.content
+        event.message.content = Resource.encode('quote', event.message.quote) + event.message.content!
       }
     }
     return event
@@ -163,7 +163,7 @@ export function defineAccessor(prototype: {}, name: string, keys: string[]) {
       // See https://github.com/satorijs/satori/issues/166
       if (value === undefined) return
       const _keys = keys.slice()
-      const last = _keys.pop()
+      const last = _keys.pop()!
       const data = _keys.reduce((data, key) => data[key] ??= {}, this)
       data[last] = value
     },
diff --git a/packages/core/tsconfig.json b/packages/core/tsconfig.json
index 0b6e1c44..3378ee05 100644
--- a/packages/core/tsconfig.json
+++ b/packages/core/tsconfig.json
@@ -3,6 +3,8 @@
   "compilerOptions": {
     "rootDir": "src",
     "outFile": "lib/index.d.ts",
+    "strict": true,
+    "noImplicitAny": false,
   },
   "include": [
     "src"
diff --git a/packages/protocol/src/index.ts b/packages/protocol/src/index.ts
index db08928f..07eaa011 100644
--- a/packages/protocol/src/index.ts
+++ b/packages/protocol/src/index.ts
@@ -492,7 +492,7 @@ export namespace WebSocket {
 }
 
 export interface WebSocket {
-  readonly url?: string
+  readonly url: string
   readonly protocol?: string
   readonly readyState?: number
   close(code?: number, reason?: string): void