backend-scaffolding

Backend Scaffolding Skill

Creates a Node.js/TypeScript backend component following the CMDO (Config, Model, DAL, Operator) architecture. Scaffolding is driven by component settings defined in sdd/sdd-settings.yaml. Delegate to the techpack-settings skill for the authoritative server settings schema — it accepts a component type (server) and returns the typed settings object including server_type, databases, provides_contracts, and framework defaults.

When to Use

Use when creating server components. Supports multiple named instances (e.g., main-server, background-worker).

Settings-Driven Scaffolding

Server components are scaffolded based on their settings in sdd/sdd-settings.yaml. Delegate to the techpack-settings skill for the complete server settings schema and defaults — it returns server_type (express/fastify/nestjs), databases (array of referenced database component names), provides_contracts (array of contract component names), and framework-specific configuration.

Conditional Scaffolding Logic

// Pseudocode for settings-driven scaffolding
const scaffoldServer = async (component: ServerComponent): Promise<void> => {
  // Always scaffold: core structure, operator lifecycle, model layer
  await scaffoldCore(component);

  // Conditional: HTTP routes (only if server provides contracts)
  if (component.settings.provides_contracts.length > 0) {
    await scaffoldRoutes(component, component.settings.provides_contracts);
  }

  // Conditional: API clients (only if server consumes contracts)
  if (component.settings.consumes_contracts.length > 0) {
    await scaffoldApiClients(component, component.settings.consumes_contracts);
  }

  // Conditional: DAL layer per database
  for (const db of component.settings.databases) {
    await scaffoldDAL(component, db);
  }
};

What It Creates

Base Structure (Always Created)

components/servers/<name>/
├── package.json
├── tsconfig.json
├── .gitignore
└── src/
    ├── index.ts                    # Entry point
    ├── config/
    │   ├── index.ts
    │   └── load_config.ts          # Config loading
    ├── operator/
    │   ├── index.ts
    │   ├── create_operator.ts      # Operator factory
    │   ├── lifecycle_probes.ts     # Health/ready endpoints (port 9090)
    │   ├── logger.ts               # Structured logging
    │   ├── metrics.ts              # Metrics collection
    │   └── state_machine.ts        # Lifecycle state machine
    ├── controller/
    │   ├── index.ts
    │   └── create_controller.ts    # Controller factory
    └── model/
        ├── index.ts
        ├── dependencies.ts         # Dependency injection interface
        ├── definitions/
        │   └── index.ts            # Empty barrel
        └── use-cases/
            └── index.ts            # Empty barrel

Conditional: HTTP Server (when server_type includes api)

└── src/
    └── operator/
        └── create_http_server.ts   # HTTP server setup (port 3000)

Conditional: HTTP Handlers (when provides_contracts is non-empty)

└── src/
    └── controller/
        └── http_handlers/
            └── index.ts            # Route handlers for contracts

Conditional: DAL Layer (when databases is non-empty)

For each database in databases, creates:

└── src/
    └── dal/
        └── <database-name>/
            └── index.ts            # DAL functions for this database
    └── operator/
        └── create_database_<name>.ts  # Database connection setup

Conditional: API Clients (when consumes_contracts is non-empty)

For each contract in consumes_contracts, generates API client from contract spec.

CMDO Architecture

| Layer | Purpose | Location | |-------|---------|----------| | Config | Configuration loading and validation | src/config/ | | Model | Business logic, definitions, use cases | src/model/ | | DAL | Data Access Layer, database operations | src/dal/ | | Operator | Application lifecycle, servers, telemetry | src/operator/ |

Plus Controller for HTTP request handling.

Directory Structure

Servers live at components/servers/<name>/:

| Component Name | Directory | |----------------|-----------| | main-server | components/servers/main-server/ | | background-worker | components/servers/background-worker/ |

Template Variables

| Variable | Description | |----------|-------------| | {{PROJECT_NAME}} | Project name | | {{PROJECT_DESCRIPTION}} | Project description | | {{PRIMARY_DOMAIN}} | Primary business domain | | {{SERVER_NAME}} | Server component name |

Templates Location

All templates are colocated in this skill's templates/ directory:

skills/components/backend/backend-scaffolding/templates/
├── package.json
├── tsconfig.json
├── .gitignore
└── src/
    ├── index.ts
    ├── config/
    ├── operator/
    ├── controller/
    ├── model/
    └── dal/

Config Integration

When scaffolding a server component, the config section is generated based on settings.

Example: API Server with Database

Settings:

- name: main-server
  type: server
  settings:
    server_type: api
    databases: [primary-db]
    provides_contracts: [public-api]

Generated config (components/config/envs/default/config.yaml):

main-server:
  port: 3000
  probesPort: 9090
  logLevel: info
  databases:
    primary-db:
      host: localhost
      port: 5432
      name: myapp
      ssl: false

Example: Worker without Database

Settings:

- name: background-worker
  type: server
  settings:
    server_type: worker
    databases: []
    provides_contracts: []
    consumes_contracts: [public-api]

Generated config:

background-worker:
  probesPort: 9090
  logLevel: info
  queue:
    url: amqp://localhost:5672
  apis:
    public-api:
      base_url: http://main-server:3000

Scaffold Spec

To scaffold a backend component, build a spec with context flags derived from settings and invoke the engine:

<plugin-root>/fullstack-typescript/system/system-run.sh scaffolding apply --spec spec.json

Variables

| Variable | Source | |----------|--------| | PROJECT_NAME | From sdd-settings.yaml project name | | SERVER_NAME | Component name | | CONTRACT_PACKAGE | @<project-name>/<contract-name> (from depends_on) |

Context Flags (derived from settings)

| Flag | Derived From | |------|-------------| | has_databases | settings.databases.length > 0 | | has_provides_contracts | settings.provides_contracts.length > 0 | | has_consumes_contracts | settings.consumes_contracts.length > 0 |

Operations

{
  "target_dir": "<project-root>",
  "base_dir": "<plugin-root>/skills",
  "variables": {
    "PROJECT_NAME": "<project-name>",
    "SERVER_NAME": "<server-name>",
    "CONTRACT_PACKAGE": "@<project-name>/<contract-name>"
  },
  "context": {
    "has_databases": true,
    "has_provides_contracts": true,
    "has_consumes_contracts": false
  },
  "operations": [
    {
      "type": "template_dir",
      "source": "components/backend/backend-scaffolding/templates",
      "dest": "components/servers/<server-name>"
    },
    {
      "type": "mkdir",
      "path": "components/servers/<server-name>/src/dal",
      "when": { "key": "has_databases", "equals": true }
    },
    {
      "type": "mkdir",
      "path": "components/servers/<server-name>/src/controller/http_handlers",
      "when": { "key": "has_provides_contracts", "equals": true }
    },
    {
      "type": "package_json_scripts",
      "scripts": {
        "<server-name>:dev": "npm run dev -w @<project-name>/<server-name>",
        "<server-name>:build": "npm run build -w @<project-name>/<server-name>",
        "<server-name>:start": "npm run start -w @<project-name>/<server-name>",
        "<server-name>:test": "npm run test -w @<project-name>/<server-name>"
      }
    }
  ]
}

Input

Schema: [`s