Customization: declared on your BasePrompt subclass via static sections and static fieldGroups. This chapter is the reference for those two structures. See Prompt Creation for how a strategy (stateless / hybrid / stateful) consumes them.

Sections & Field Groups

Sections and field groups are the two halves of mcp-rune’s prompt structure. Sections define the user-facing workflow — how an LLM walks the user through a creation or update flow. Field groups define validation — which fields belong together and what rules apply. They live side by side in every prompt class, and the framework derives field tables, flow diagrams, and per-section docs from both.

This guide is the reference for how the two work together. For the strategy that consumes them (stateless / hybrid / stateful), see the Prompt Creation guide.

Why sections?

1. Separation of concerns — display structure (sections) vs validation structure (fieldGroups)
2. Scalability — add new fieldGroups to existing sections without changing the user-facing workflow
3. Flexibility — multiple fieldGroups can be grouped under one section
4. Single source of truth — section titles and descriptions defined once

The relationship is one-section-to-many-groups, with fields mapped at the group level:

Left column is what the LLM walks the user through; right column is what validateSection evaluates. A section can carry one or many field groups — that’s how a “Timing” section can host both a “when” group and a “duration” group without changing the user-facing flow.

Sections vs FieldGroups

Defining sections

static sections = {
  basics: {
    title: 'Basic Information',
    description: 'Title and description for the activity',
    required: true,
    groups: ['basics'],
    content: {
      intro: 'The title and description that identify the activity.'
    }
  },
  classification: {
    title: 'Classification',
    description: 'Theme and category for organizing the activity',
    required: true,
    groups: ['classification'],
    content: {
      notes: [
        'Use `find_records(model: "theme")` to find the theme',
        'Use `find_records(model: "category")` to find the category'
      ]
    }
  },
  timing: {
    title: 'Timing',
    description: 'When the activity occurred and how long it lasted',
    required: false,
    groups: ['timing'],
    content: {
      intro: 'When the activity occurred and how long it lasted.'
    }
  }
}

static sections = {
  basics: {
    title: 'Basic Information',
    description: 'Title and description for the activity',
    required: true,
    groups: ['basics'],
    content: {
      intro: 'The title and description that identify the activity.'
    }
  },
  classification: {
    title: 'Classification',
    description: 'Theme and category for organizing the activity',
    required: true,
    groups: ['classification'],
    content: {
      notes: [
        'Use `find_records(model: "theme")` to find the theme',
        'Use `find_records(model: "category")` to find the category'
      ]
    }
  },
  timing: {
    title: 'Timing',
    description: 'When the activity occurred and how long it lasted',
    required: false,
    groups: ['timing'],
    content: {
      intro: 'When the activity occurred and how long it lasted.'
    }
  }
}

Section content enrichment

Sections support a content property with intro and notes that are automatically rendered in the generated section documentation. Use these to add domain-specific context without writing custom section generator methods.

How it works: When .allSections() or .section() renders a section, it automatically:

1. Adds content.intro before the field table
2. Generates the field table from fieldDefinitions
3. Generates enum tables for any field with enumDescriptions
4. Adds content.notes as a bullet list
5. Adds the askPrompt prompt

Key principle: Prefer content.intro and content.notes over custom generateSectionXDocumentation() methods. This keeps domain content in configuration and lets the framework auto-generate field tables and enum tables alongside it.

Per-group content (multi-group sections)

When a section contains multiple groups (groups: ['group_a', 'group_b']), each group can have its own context (display name) and content: { intro, notes } defined in fieldGroups. The generator renders each group as a ### sub-section with its own field table.

Key behaviors:

• context defaults to title-cased group name if absent (snake_case_name → “Snake Case Name”)
• Groups without content render just a heading and field table (no intro/notes)
• Single-group sections are completely unchanged — they read from section.content as before
• context and content on fieldGroups are ignored by StatefulFormStrategy (no breaking changes to validation)

Defining fieldGroups (simplified)

With sections as first-class citizens, fieldGroups focus on validation:

static fieldGroups = {
  basics: {
    fields: ['title', 'description'],
    context: 'Basic Information',
    required: true,
    description: 'Title and description for the activity'
  },
  classification: {
    fields: ['theme_id', 'category_id'],
    context: 'Classification',
    required: true,
    description: 'Theme and category for organizing the activity'
  }
}

static fieldGroups = {
  basics: {
    fields: ['title', 'description'],
    context: 'Basic Information',
    required: true,
    description: 'Title and description for the activity'
  },
  classification: {
    fields: ['theme_id', 'category_id'],
    context: 'Classification',
    required: true,
    description: 'Theme and category for organizing the activity'
  }
}

Section helper methods

BasePrompt keeps a small set of section-related statics:

For section enumeration with metadata (fields, numbering, progress), use StatefulFormStrategy.getSections(PromptClass) from the Stateful Strategies guide.

Flow diagram generation

The builder’s .flowDiagram() step (backed by generateFlowDiagram in generators/flow-diagram-generator.ts) uses sections to create a compact flow overview:

// Auto-generated from sections config
**Flow:** (● required, ○ optional)
● 1. BASIC INFORMATION - title, description
● 2. CLASSIFICATION - theme_id, category_id
○ 3. TIMING - started_at, ended_at, duration_minutes
○ 4. RESOURCES - book_ids, notes_generated
● 5. SUMMARY

// Auto-generated from sections config
**Flow:** (● required, ○ optional)
● 1. BASIC INFORMATION - title, description
● 2. CLASSIFICATION - theme_id, category_id
○ 3. TIMING - started_at, ended_at, duration_minutes
○ 4. RESOURCES - book_ids, notes_generated
● 5. SUMMARY

See also

• Prompt Creation guide — the strategies (stateless / hybrid / stateful) that consume these sections.
• Stateful Strategies guide — per-section validation and progress tracking on top of this structure.
• Prompt Derivation Framework guide — Layer 2 of the derivation pipeline where this content is consumed.