koapp-model

A JavaScript Model class for copying data into typed objects, validating fields with validatorjs rules, and converting objects to JSON or plain data.

In plain words
What is it for?
Use it to build validated request or response models, enforce rules such as required, integer, email, minimum, and maximum, and serialize model data.
Why use it?
It centralizes input validation and can turn invalid request data into a standard HTTP 400 error without repeated handler code.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/axiosleo/node-koapp/koapp-model
Any agent
npx skills add AxiosLeo/node-koapp --skill koapp-model
Clone the repo
git clone --depth 1 https://github.com/AxiosLeo/node-koapp

Made for: Claude Code, Codex.

Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,485 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00068 $0.01485
Opus 5 $0.00034 $0.00743
Sonnet 5 $0.00014 $0.00297
Haiku 4.5 $0.00007 $0.00148

Measured 2d ago against content hash ac2591a5920a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

koapp-model scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

assets/skills/koapp-model/SKILL.md · 193 lines

How it starts

The opening of the file, as written. The whole thing — 193 lines — stays where its author put it; the contents beside it link to each section on GitHub.

@axiosleo/koapp Model

Source: src/model.js.

Model is a lightweight data container around validatorjs. It assigns incoming fields onto itself, optionally validates them, and provides utility methods for serialization.

Import

const { Model } = require('@axiosleo/koapp');

Constructor

new Model(obj?, rules?, messages?);
Arg Type Purpose
obj object Source data; each key is copied onto the instance via Object.assign
rules Rules validatorjs rule set, e.g. `{ name: 'required
messages ErrorMessages Custom error messages keyed by rule, e.g. { required: 'The :attribute is required.' }

When rules are provided and validation fails, the constructor throws HttpError(400, <first-error-message>). Inside a koapp handler that translates to a standard 400 response without any extra plumbing.

Static helper

Model.create(obj, rules, messages);

Shortcut for new Model(obj, rules, messages) that benefits from subclass context (same as new this(...)).

Instance methods

Method Returns Notes
toJson() string JSON.stringify(this)
toObj() object JSON.parse(this.toJson()); strips class identity
properties() string[] Enumerable own keys
count() number properties().length
validate(rules, messages?) Validator Runs validatorjs manually and returns the raw Validator object

validate() does not throw - use it when you need the full error map:

const m = new Model({ email: 'not-an-email' });
const v = m.validate({ email: 'required|email' });
if (v.fails()) {
  console.log(v.errors.all()); // { email: ['The email format is invalid.'] }
}

Extending Model

class UserModel extends Model {
  constructor(data) {
    super(data, {
      name: 'required|string',
      email: 'required|email',
      age: 'integer|min:0'
    }, {
      required: 'The :attribute field is required.'
    });
  }

  greet() {
    return `Hi, ${this.name}`;
  }
}

const user = new UserModel(context.body);
// If the body fails validation, HttpError(400, ...) is thrown automatically.

Read the full file on GitHub · 193 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 193 lines · 68 tokens per session scan A ac2591a5920a

Subscribe to this mod's changes

koapp-model is a skill published in the GitHub repository AxiosLeo/node-koapp (145 stars, last pushed 19d ago), licensed MIT. It adds 68 tokens to every session and 1,485 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

brainstorming

You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.

obra/superpowers · 37 tokens

auto-perf-optimize

Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.

microsoft/vscode · 62 tokens

chat-perf

Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.

microsoft/vscode · 51 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens