viyan-mcp: Skill for Claude Code

When to Use

Use this skill when configuring security modules, implementing user authentication, restricting tool access via guards, or handling sensitive tokens.

---

1. JSON Web Tokens (JWT)

To secure tools with JWT authentication:

Register JWTModule:

import { JWTModule, Module, McpApp } from '@nitrostack/core';

@McpApp({
  server: { name: 'my-server', version: '1.0.0' }
})
@Module({
  imports: [
    JWTModule.forRoot({
      secret: process.env.JWT_SECRET!,
      expiresIn: '7d',
    }),
  ]
})
export class AppModule {}

Write a JWTGuard:

import { Guard, ExecutionContext, Injectable, ConfigService } from '@nitrostack/core';
import * as jwt from 'jsonwebtoken';

@Injectable()
export class JWTGuard implements Guard {
  constructor(private config: ConfigService) {}

  async canActivate(context: ExecutionContext): Promise<boolean> {
    const token = this.extractToken(context);
    if (!token) return false;

    try {
      const secret = this.config.get('JWT_SECRET');
      const payload = jwt.verify(token, secret) as any;
      context.auth = {
        subject: payload.sub,
        role: payload.role,
        token,
      };
      return true;
    } catch {
      return false;
    }
  }

  private extractToken(context: ExecutionContext): string | null {
    const auth = context.metadata?.authorization;
    if (auth?.startsWith('Bearer ')) {
      return auth.substring(7);
    }
    return null;
  }
}

---

2. API Key Authentication

Use ApiKeyModule for service-to-service validation.

Register ApiKeyModule:

import { ApiKeyModule, Module } from '@nitrostack/core';

@Module({
  imports: [
    ApiKeyModule.forRoot({
      keysEnvPrefix: 'API_KEY', // Reads API_KEY_1, API_KEY_2, etc.
      headerName: 'x-api-key',
      hashed: false,
    }),
  ]
})
export class AppModule {}

API Key Guard:

import { Guard, ExecutionContext, ApiKeyModule } from '@nitrostack/core';

export class ApiKeyGuard implements Guard {
  async canActivate(context: ExecutionContext): Promise<boolean> {
    const apiKey = context.metadata?.['x-api-key'] || context.metadata?.apiKey;
    if (!apiKey) return false;

    const isValid = await ApiKeyModule.validate(apiKey as string);
    if (isValid) {
      context.auth = {
        subject: `apikey_${(apiKey as string).substring(0, 10)}`,
        scopes: ['*'],
      };
      return true;
    }
    return false;
  }
}