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Inheritance Guide

Learn how to build scalable, maintainable instruction hierarchies using PromptScript's inheritance system.

Overview

PromptScript uses single inheritance to build hierarchical instruction sets:

flowchart TD
    A["@org/base<br/>Organization defaults"] --> B["@org/frontend<br/>Frontend team"]
    A --> C["@org/backend<br/>Backend team"]
    B --> D["project-web<br/>Web application"]
    B --> E["project-mobile<br/>Mobile app"]
    C --> F["project-api<br/>API service"]

Basic Inheritance

Use @inherit to extend another PromptScript file:

@meta {
  id: "my-project"
  syntax: "1.0.0"
}

@inherit @company/frontend-team

The child inherits all blocks from the parent, which can then be extended.

Registry Structure

Organize your registry with namespaces:

registry/
├── @company/
│   ├── base.prs           # Organization base
│   ├── frontend.prs       # Frontend team
│   ├── backend.prs        # Backend team
│   └── mobile.prs         # Mobile team
├── @core/
│   ├── security.prs       # Security standards
│   └── compliance.prs     # Compliance rules
└── @fragments/
    ├── testing.prs        # Testing patterns
    └── logging.prs        # Logging standards

Merge Behavior

Different blocks merge differently during inheritance:

Text Blocks (Concatenate)

@identity, @knowledge, and text content in other blocks concatenate:

# Parent
@identity {
  """
  You are a helpful assistant.
  """
}

# Child
@inherit ./parent

@identity {
  """
  You specialize in React development.
  """
}

## Identity

You are a helpful assistant.

You specialize in React development.

Objects (Deep Merge)

@standards and object properties deep merge:

# Parent
@standards {
  code: {
    style: "clean"
    testing: required
  }
}

# Child
@inherit ./parent

@standards {
  code: {
    frameworks: [react]  # Added
    testing: {           # Overrides primitive with object
      required: true
      coverage: 80
    }
  }
}

code:
  style: "clean"         # From parent
  frameworks: [react]    # From child
  testing:               # Child object replaces parent primitive
    required: true
    coverage: 80

Arrays (Concatenate)

@restrictions and array values concatenate:

# Parent
@restrictions {
  - "Never expose secrets"
}

# Child
@inherit ./parent

@restrictions {
  - "Always use TypeScript"
}

## Restrictions

- Never expose secrets
- Always use TypeScript

Shortcuts (Override)

@shortcuts entries override by key:

# Parent
@shortcuts {
  "/test": "Write unit tests"
  "/docs": "Generate documentation"
}

# Child
@inherit ./parent

@shortcuts {
  "/test": "Write tests with Vitest"  # Overrides
  "/lint": "Run ESLint"               # Added
}

## Shortcuts

| Command | Description |
|---------|-------------|
| /test | Write tests with Vitest |
| /docs | Generate documentation |
| /lint | Run ESLint |

Using @extend

The @extend block modifies specific paths:

Extending Top-Level Blocks

@inherit @company/base

# Add to identity
@extend identity {
  """
  Additional identity context.
  """
}

Extending Nested Paths

@inherit @company/base

# Modify nested structure
@extend standards.code.testing {
  e2e: required
  coverage: 90
}

Multiple Extensions

@inherit @company/base

@extend identity {
  """
  You are a frontend expert.
  """
}

@extend standards.code {
  framework: "react"
}

@extend restrictions {
  - "Use functional components only"
}

Composition with @use

Use @use to import fragments without full inheritance:

@meta {
  id: "my-project"
  syntax: "1.0.0"
}

@inherit @company/frontend

# Import additional fragments
@use @core/security
@use @fragments/testing as tests

Fragment Files

Create reusable fragments:

# @fragments/testing.prs
@meta {
  id: "@fragments/testing"
  syntax: "1.0.0"
}

@standards {
  testing: {
    framework: "vitest"
    coverage: 80
    patterns: ["unit", "integration"]
  }
}

@shortcuts {
  "/test": "Write comprehensive tests"
  "/coverage": "Check test coverage"
}

Best Practices

1. Keep Base Configurations Minimal

Organization base should include only universal standards:

# @company/base.prs
@meta {
  id: "@company/base"
  syntax: "1.0.0"
}

@identity {
  """
  You are an AI assistant at ACME Corp.
  Follow company guidelines and best practices.
  """
}

@restrictions {
  - "Never expose credentials"
  - "Follow data protection policies"
}

2. Use Team Configurations for Specialization

# @company/frontend.prs
@meta {
  id: "@company/frontend"
  syntax: "1.0.0"
}

@inherit @company/base

@identity {
  """
  You specialize in frontend development.
  """
}

@context {
  """
  Tech stack: React, TypeScript, Vite
  """
}

3. Project Configurations for Specifics

# project.prs
@meta {
  id: "checkout-app"
  syntax: "1.0.0"
}

@inherit @company/frontend

@context {
  project: "Checkout Application"

  """
  E-commerce checkout flow with Stripe integration.
  """
}

4. Version Your Registry

Use semantic versioning for registry files:

@inherit @company/frontend@1.0.0

5. Document Inheritance Chains

Include comments explaining the hierarchy:

# Inheritance chain:
# @company/base → @company/frontend → this file
@inherit @company/frontend

Common Patterns

Platform-Specific Configurations

flowchart TD
    A["@company/base"] --> B["@company/web"]
    A --> C["@company/mobile"]
    A --> D["@company/backend"]

    B --> E["@company/web-react"]
    B --> F["@company/web-vue"]

    C --> G["@company/mobile-ios"]
    C --> H["@company/mobile-android"]

Shared Standards with Team Overrides

# Use shared security, override team-specific
@inherit @company/frontend
@use @core/security
@use @core/compliance

@extend standards.security {
  additionalRules: ["CSP headers"]
}

Environment-Specific Extensions

@inherit @company/frontend

@context {
  environment: production
}

@extend restrictions {
  - "No console.log statements"
  - "No debug code"
}

Debugging Inheritance

View Resolved Configuration

prs compile --dry-run --verbose

Validate Inheritance Chain

prs validate --verbose

Common Issues

Circular inheritance detected:

Error: Circular inheritance: a → b → a

Ensure no circular references in your inheritance chain.

Parent not found:

Error: Cannot resolve @company/unknown

Check registry configuration and file paths.

Version mismatch:

Warning: Requested @company/base@2.0.0, found 1.5.0

Update version constraints or registry.