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@apeira/plugin-skills

A skill system for Apeira with multi-source support. Skills are named instruction sets that the model can load on demand via a skill tool.

Install

pnpm add @apeira/plugin-skills

Usage

Filesystem skill set (built-in, Node.js only)

import { createAgent } from '@apeira/core'
import { responses } from '@apeira/core/responses'
import { skills } from '@apeira/plugin-skills'
import { fsSkillSet } from '@apeira/plugin-skills/fs'

const mySkills = fsSkillSet({ directory: '.agents/skills' })

const agent = createAgent({
  instructions: 'You are a helpful assistant.',
  plugins: [skills({ sets: [mySkills] })],
  runner: responses({
    apiKey: process.env.OPENAI_API_KEY,
    baseURL: 'https://api.openai.com/v1/',
    model: 'gpt-5.5',
  }),
})

Multiple skill sets with priority

const localSkills = fsSkillSet({ directory: '.agents/skills', priority: 0 })

const customSkills = createSkillSet({
  skills: [{
    content: '# Math\nUse proper notation and show steps.',
    description: 'Expert math problem solving.',
    filePath: '.agents/skills/math/SKILL.md',
    name: 'math',
  }],
})

const agent = createAgent({
  plugins: [
    skills({
      sets: [localSkills, customSkills],
    }),
  ],
})

API

skills(options?)

Creates an Apeira plugin that:

• Injects available skill metadata into the system prompt via extendInstructions
• Provides a skill tool for the model to load skill content
• Optionally provides a skill_reference tool for reference files
• Supports refresh: 'turn' to reload skills before each turn

createSkillSet(options?)

Creates a skill set backed by inline skills or custom loader functions.

fsSkillSet(options) (@apeira/plugin-skills/fs)

Creates a skill set that reads skills from a filesystem directory. Each skill is expected to be in a subdirectory: <directory>/<skill-name>/SKILL.md with optional YAML frontmatter (name, description) and an optional references/ subdirectory.

Option	Type	Default	Description
directory	string	—	Base directory containing skill subdirectories
allowedReferenceExtensions	string[]	['.md', '.mdx', '.txt']	Allowed reference file extensions
priority	number	—	Priority for deduplication when merged with other sets

Composite via sets option

When you pass multiple SkillSet instances via the sets option, skills are merged automatically. Higher priority wins dedup; if equal, earlier in the array wins.

Skill

Field	Type	Description
name	string	Unique skill identifier
description	string	Shown to the model for skill selection
content	string	Full instruction content
filePath	string	Source location (for reference resolution)
references?	SkillReference[]	Reference file manifests

SkillsPluginOptions

Option	Type	Default	Description
sets	SkillSet[]	—	Skill sets to merge
skills	Skill[]	—	Static skills (convenience for trivial cases — no refresh, no priority)
refresh	'manual' | 'turn'	'turn' when sets is provided, else 'manual'	When to reload skills
instructionsBudget	number	~2% of state.contextLength (fallback 2560 tokens)	Token budget for the <available_skills> section in the system prompt
toolName	string	'skill'	Name for the skill tool
referenceToolName	string	'skill_reference'	Name for the reference tool

Features

• Multiple skill sets — combine filesystem, inline, remote, or custom sets
• Built-in FS skill set — reads skills from <dir>/<name>/SKILL.md with YAML frontmatter
• Model invocation — the model chooses when to load a skill via the skill tool
• Reference system — skills can reference external files loaded lazily
• Refresh modes — manual or turn (reload before each turn)
• Decoupled I/O — core package has no Node.js deps; FS support is a subpath import