How do I install the J5ik2o First Class Collection skill?

Run npx skillmds@latest add j5ik2o/j5ik2o-first-class-collection in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is J5ik2o First Class Collection safe to use?

This skill has not completed SkillMD's automated safety review yet. Independent scanners report: SkillSpector: PASS, Skill Scanner: PASS. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with J5ik2o First Class Collection?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is J5ik2o First Class Collection free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published J5ik2o First Class Collection?

j5ik2o (@j5ik2o) published this skill. Their other Agent Skills are listed on their SkillMD profile.

J5ik2o First Class Collection by j5ik2o

Name: J5ik2o First Class Collection
Author: j5ik2o

J5ik2o First Class Collection

Use when wrapping collections in a domain-specific class to centralize collection rules, invariants, and behavior. Trigger for scattered list logic, collection wrappers, raw Order lists becoming `Orders`, enforcing collection invariants, or reviewing collection-heavy domain code.

j5ik2o Updated Sep 21, 2026

File contents

First Class Collection

A first-class collection gives a collection a domain name and keeps collection rules in one place.

Rule

The wrapper should own one collection field and behavior around that collection. Extra unrelated fields usually mean it is an entity or aggregate instead.

Workflow

Find repeated collection operations, filters, totals, limits, ordering, or validation.
Name the collection as a domain concept.
Move rules into methods on the wrapper.
Keep the internal collection immutable or defensively copied.
Expose intention-revealing operations instead of raw mutation.

Checks

Good: OrderLines.totalAmount(), Members.hasQuorum().
Bad: exposing items and expecting callers to remember invariants.
Avoid wrapping a collection that has no domain behavior.

Reference

Read references/patterns.md for implementation patterns.

Detailed Reference

For non-trivial implementation, review, or refactoring work, read references/details.md before giving final guidance. It contains the detailed rules, examples, smells, and migration notes that do not belong in the short invocation body.

Output

Return wrapper candidates, APIs, invariants, and migration steps.

Frequently asked questions