Config Scaffolding Skill

Scaffolds the mandatory config component for centralized configuration management. Config sections are generated based on component settings from sdd/sdd-settings.yaml. Delegate to the techpack-settings skill for the authoritative config schema — it accepts a component type (config) and returns the settings object including referenced components and environment variable mappings.

When to Use

Use during project initialization to create the config component. The config component is mandatory — every SDD project has exactly one.

What It Creates

components/config/
├── package.json                # Minimal package for workspace imports
├── tsconfig.json               # TypeScript config for type exports
├── envs/
│   ├── default/
│   │   └── config.yaml         # Base config (sections per component)
│   └── local/
│       └── config.yaml         # Local overrides (empty)
├── schemas/
│   └── config.schema.json      # Main schema (minimal)
└── types/
    └── index.ts                # Re-exports config types

Settings-Driven Config Generation

Config sections are generated based on component settings in sdd/sdd-settings.yaml:

Server Config Sections

API Server with database:

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

# Generated config:
main-server:
  port: 3000                    # Business API port (has provides_contracts)
  probesPort: 9090              # Health/metrics port (always)
  logLevel: info                # Logging level (always)
  databases:
    primary-db:                 # Section per database
      host: localhost
      port: 5432
      name: myapp
      ssl: false

Worker without database:

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

# Generated config:
background-worker:
  probesPort: 9090              # Health/metrics port (always)
  logLevel: info                # Logging level (always)
  queue:                        # Queue config for worker
    url: amqp://localhost:5672
  apis:
    public-api:                 # Section per consumed contract
      base_url: http://main-server:3000

Hybrid server (api + worker):

# Settings:
- name: main-server
  type: server
  settings:
    server_type: hybrid
    modes: [api, worker]
    databases: [primary-db]
    provides_contracts: [public-api]

# Generated config:
main-server:
  port: 3000                    # Business API port (has provides_contracts)
  probesPort: 9090              # Health/metrics port (always)
  logLevel: info                # Logging level (always)
  databases:
    primary-db:
      host: localhost
      port: 5432
      name: myapp
      ssl: false
  queue:                        # Queue config (has worker mode)
    url: amqp://localhost:5672

Webapp Config Sections

# Settings:
- name: admin-dashboard
  type: webapp
  settings:
    contracts: [public-api]

# Generated config:
admin-dashboard:
  apis:
    public-api:                 # Section per consumed contract
      base_url: http://localhost:3000

Config Section Rules

Setting	Config Impact
server_type: api	Adds port: 3000 (business API)
server_type: worker	Adds queue: { url: ... }
server_type: cron	Adds schedule: {} placeholder
provides_contracts: [...]	Adds port: 3000 (business API)
consumes_contracts: [...]	Adds apis: { <name>: { base_url: ... } } per contract
databases: [...]	Adds databases: { <name>: { host, port, name, ssl } } per database
contracts: [...] (webapp)	Adds apis: { <name>: { base_url: ... } } per contract

All Servers Get

• probesPort: 9090 - Health check and metrics endpoint
• logLevel: info - Logging level

Config Component Purpose

The config component is a minimal TypeScript project with no runtime code. It exists so:

1. Other components can import types via workspace package @{project}/config/types
2. YAML files are the source of truth for configuration values
3. The system CLI (via /sdd I want to generate config) generates merged configs for each environment

Environment Structure

Each environment has its own directory under envs/:

Directory	Purpose
envs/default/	Base configuration - all environments inherit from this
envs/local/	Local development overrides (always present)
envs/{env}/	Other environments added as needed (staging, production, etc.)

Merge order: envs/default/ → envs/{env}/

Template Variables

Variable	Description
{{PROJECT_NAME}}	Project name (lowercase, hyphens)

Templates Location

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

skills/components/config/config-scaffolding/templates/
├── package.json
├── tsconfig.json
├── envs/
│   ├── default/
│   │   └── config.yaml
│   └── local/
│       └── config.yaml
├── schemas/
│   └── config.schema.json
└── types/
    └── index.ts

Sync Behavior

When settings change (via /sdd with natural language about settings), the config component is automatically synced:

1. New component added → Config section added with defaults
2. Database added to server → Database subsection added
3. Contract added to consumes_contracts → API subsection added
4. Existing sections → Never modified or deleted (preserves user changes)

Scaffold Spec

The config component uses the engine for base template structure, but config section generation is dynamic (computed from component settings by the skill).

Base structure via engine

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

{
  "target_dir": "<project-root>",
  "base_dir": "<plugin-root>/skills",
  "variables": { "PROJECT_NAME": "<project-name>" },
  "operations": [
    {
      "type": "template_dir",
      "source": "components/config/config-scaffolding/templates",
      "dest": "components/config"
    }
  ]
}

Dynamic config sections (skill computes content)

For each component, the skill computes the YAML config section content and writes it via write_file with if_exists: "skip" (additive only — never clobber existing sections). The skill builds the YAML content itself, then passes it to the engine.

{
  "type": "write_file",
  "path": "components/config/envs/default/config.yaml",
  "content": "<computed-yaml-content>",
  "if_exists": "overwrite"
}

Split: Use the engine for the component directory structure. Compute config sections yourself (from component settings) and write them via write_file.

Input

Schema: schemas/input.schema.json

Accepts the full list of project components whose settings drive dynamic config section generation.

Output

Schema: schemas/output.schema.json

Returns the scaffolding engine result: created files, directories, and scripts; skipped paths; errors; and a human-readable summary.

Related Skills

• config-standards — Generated config files must follow these standards. Defines naming conventions, validation patterns, environment-specific overrides, and TypeScript type generation rules.