Inheritance System

Overview

The prompd inheritance system allows prompt templates to extend and build upon other templates, similar to object-oriented programming inheritance. This enables code reuse, standardization, and composition of complex AI workflows from simpler components.

Key Inheritance Rules

1. File Path Resolution: Inherit from local files (./base.prmd) or package files ("@scope/package@version/path.prmd")
2. Content Merging: Child content is appended after parent content (not merged)
3. Parameter Merging: Child parameters override parent parameters by name
4. Context Merging: Child context arrays are merged with parent context
5. Package References: All @ references must be quoted for valid YAML

Basic Inheritance Syntax

Local File Inheritance

---
id: child-template
name: "Child Template"
inherits: "./base-template.prmd"
parameters:
  - name: model
    type: string
    default: "gpt-4o"  # Override parent value
---

Child-specific content is appended after parent content.

Syntax requirements:

• Use forward slashes / even on Windows
• Relative paths start with ./ or ../
• File extension .prmd is required

Package Reference Inheritance

---
id: security-audit-specialized
name: "Fintech Security Audit"
inherits: "@prompd.io/security-toolkit@1.0.0/prompts/security-audit.prmd"
parameters:
  - name: compliance_requirements
    type: array
    default: ["PCI-DSS", "SOX", "FFIEC"]
---

Additional fintech-specific security requirements...

Quote package references

Package references starting with @ must be quoted in YAML. The @ character is reserved in YAML syntax.

# WRONG - Will cause YAML parsing errors
inherits: @prompd.io/package@1.0.0/prompts/base.prmd

# CORRECT - Properly quoted
inherits: "@prompd.io/package@1.0.0/prompts/base.prmd"

Section-Based Content Override

For precise control over inherited content, use section-based overrides to selectively replace or remove specific sections:

---
name: "Healthcare Security Audit"
inherits: "./base-security-audit.prmd"
override:
  system-prompt: "./healthcare-system-prompt.md"
  examples: null  # Remove section
  compliance-requirements: "./hipaa-compliance.md"
---

Discover available sections with:

prompd show base-template.prmd --sections

What Gets Inherited

Parameters

• Parent parameters are inherited
• Child parameters with the same name override parent parameters
• Child can add new parameters

# Parent template
parameters:
  - name: temperature
    type: number
    default: 0.7
  - name: model
    type: string
    default: "gpt-3.5-turbo"

# Child template
parameters:
  - name: model
    type: string
    default: "gpt-4o"       # Overrides parent
  - name: system_role        # New parameter
    type: string
    default: "security expert"

Content

• Parent content is included first
• Child content is appended after parent content
• No content merging - purely additive

Metadata Fields

• id, name, description, version can be overridden
• author is inherited unless overridden
• Custom fields are merged

Context Arrays

• Parent context files are included
• Child context files are appended to the list

Override Behavior

YAML Fields vs Markdown Content

YAML frontmatter fields and markdown content are completely separate systems:

YAML field override works:

# child.prmd
---
inherits: "./parent.prmd"
system: "You are a security expert"  # Overrides parent YAML field
---

Markdown headers do NOT override YAML:

# child.prmd
---
inherits: "./parent.prmd"
# No system: field here
---
# System
You are a security expert  # Does NOT override parent's system YAML field

Override Rules Summary

• YAML to YAML: Child YAML fields completely override parent YAML fields
• Markdown to Markdown: Child markdown is appended to parent markdown
• YAML to Markdown: No interaction - completely separate
• Markdown to YAML: No interaction - completely separate

Package References

Package references can appear in any YAML field and must include the full file path:

---
id: comprehensive-security-audit
using:
  - name: "@prompd.io/api-toolkit@1.2.1"
    prefix: "@api"
  - name: "@prompd.io/security-toolkit@1.0.0"
    prefix: "@security"
inherits: "@prompd.io/core-patterns@2.0.0/templates/analysis-framework.prmd"
system: "@security/systems/security-expert.prmd"
context:
  - "@security/contexts/owasp-top-10.md"
  - "./local-context.md"
---

Working Examples

Basic Local Inheritance

base-security-audit.prmd:

---
id: base-security-audit
name: "Base Security Audit"
version: "0.0.1"
description: "Base Security Audit example"
parameters:
  - name: application_name
    type: string
    required: true
  - name: technology_stack
    type: string
    required: true
  - name: audit_scope
    type: string
    enum: [basic, comprehensive]
    default: basic
---

# Security Audit for {{ application_name }}

## Technology Stack

- **Stack:** {{ technology_stack }}
- **Audit Scope:** {{ audit_scope }}

## Base Security Assessment

Perform standard security evaluation including:

- Input validation review
- Authentication mechanism analysis
- Authorization control verification

security-audit.prmd (child):

---
id: security-audit
name: "Comprehensive Security Audit"
version: "0.0.1"
description: "Comprehensive Security Audit example inheritance."
inherits: "./base-security-audit.prmd"
parameters:
  - name: application_name
    type: string
    required: true
  - name: technology_stack
    type: string
    required: true
  - name: audit_scope
    type: string
    enum: [basic, comprehensive, compliance]
    default: comprehensive  # Override parent default
  - name: compliance_requirements
    type: array
    items:
      enum: [SOC2, PCI-DSS, HIPAA, GDPR]
    required: false
---

## Advanced Security Testing

### OWASP Top 10 Assessment

### Penetration Testing Simulation

{% if compliance_requirements %}

### Compliance Validation
{% for item in compliance_requirements %}
- **{{ item }} Compliance:** Evaluate against {{ item }} security controls
{% endfor %}

{% endif %}

Package Inheritance

---
id: fintech-security-audit
name: "Fintech Security Audit"
inherits: "@prompd.io/security-toolkit@1.0.0/prompts/security-audit.prmd"
parameters:
  - name: compliance_requirements
    type: array
    default: ["PCI-DSS", "SOX", "FFIEC"]
  - name: financial_data_types
    type: array
    items:
      enum: [card_data, account_numbers, transaction_data, pii]
    required: true
context:
  - "@prompd.io/fintech-context@1.2.0/contexts/pci-requirements.md"
  - "./fintech-specific-rules.md"
---

## Financial Services Specific Requirements

{% for item in financial_data_types %}
- **{{ item }}**: Enhanced protection requirements
{% endfor %}

Advanced Patterns

Chained Inheritance

Create inheritance chains where each level adds specialization:

base-analysis.prmd
├── security-analysis.prmd
│   ├── web-security-audit.prmd
│   └── api-security-audit.prmd
└── performance-analysis.prmd

Keep inheritance chains shallow - maximum 3-4 levels deep. Prefer composition over deep inheritance.

Supported File Types in References

You can reference external files in any YAML field (system:, user:, assistant:, context:, inherits:):

Text Files (Direct Content):

system: "./prompts/system-prompt.txt"
context:
  - "./data/sample-code.py"
  - "./data/export.csv"

Structured Data (Formatted Output):

context:
  - "./config/api-settings.json"   # Pretty JSON with markdown
  - "./deployment/k8s-config.yaml" # Formatted YAML

Binary Files (Automatic Extraction):

context:
  - "./reports/analysis.xlsx"    # Extracted as CSV/tabular data
  - "./docs/manual.docx"        # Plain text extraction
  - "./documents/policy.pdf"    # OCR text extraction

Supported binary formats: Excel (.xlsx, .xlsm), Word (.docx), PowerPoint (.pptx), PDF (.pdf), Images (.png, .jpg, .gif, .bmp, .webp).

Troubleshooting

Common Errors

YAML Syntax Errors with Package References:

# WRONG
inherits: @prompd.io/package@1.0.0/prompts/base.prmd

# CORRECT
inherits: "@prompd.io/package@1.0.0/prompts/base.prmd"

File Not Found: Verify relative paths are correct from the child file’s location:

# If child is in ./specialized/audit.prmd
# and base is in ./base.prmd
inherits: "../base.prmd"

Package Path Errors: Include the full file path within the package:

# WRONG - Missing file path
inherits: "@prompd.io/toolkit@1.0.0"

# CORRECT - Include full path
inherits: "@prompd.io/toolkit@1.0.0/prompts/base-tool.prmd"

Testing Inheritance

# Compile the template
prompd compile ./child-template.prmd --to-markdown -o output.md

# Check parameter resolution
prompd show ./child-template.prmd

# Validate package references
prompd deps ./child-template.prmd