# Roblox Luau Types

> >

- **Type:** Skill
- **Install:** `agentstack add skill-tabooharmony-roblox-brain-roblox-luau-types`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [TabooHarmony](https://agentstack.voostack.com/s/tabooharmony)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [TabooHarmony](https://github.com/TabooHarmony)
- **Source:** https://github.com/TabooHarmony/roblox-brain/tree/main/skills/roblox-luau-types

## Install

```sh
agentstack add skill-tabooharmony-roblox-brain-roblox-luau-types
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Luau Type System

## When to Load

Load this skill when working with Luau type annotations, generics, union types, type narrowing, or sealed/unsealed table behavior. Also load when choosing strictness modes (`--!strict` vs `--!nonstrict`), designing module type exports, or typing metatable-backed objects.

## Quick Reference

**Strictness:** `--!strict` (new code), `--!nonstrict` (transitional), `--!nocheck` (legacy only). The New Type Solver (GA Nov 2025) is faster/more accurate.

**Inference philosophy:** Infer first, annotate boundaries (params, returns, exports). Don't annotate every local — noise hides signal.

**Sealed vs unsealed tables:**
```luau
local t = {}          -- unsealed: can add fields
t.x = 1               -- OK

local t: {x: number} = {x=1}  -- sealed: no new fields
t.y = 2               -- ERROR
```
Build tables fully before annotating. Passing/returning seals them.

**Unions & tagged unions:**
```luau
local id: string | number = "abc"
type State = {kind:"loading"} | {kind:"ready", value:T} | {kind:"fail", msg:string}
-- Discriminate: if state.kind == "ready" then state.value is narrowed
```

**Narrowing:**
```luau
if typeof(x) == "string" then ... end          -- primitive narrowing
if inst:IsA("BasePart") then ... end           -- Instance narrowing
assert(val, "missing")                          -- non-nil narrowing
```

**Generics:** Use when input→output type matters. `function first(list: {T}): T?`. Generic aliases: `type Result = {success: boolean, value: T?}`. Never replace with `any`.

**Type exports:** `export type Foo = {...}` at module boundary. Consumers use `require` + `Types.Foo`.

**Object typing:** `export type Counter = typeof(setmetatable({} :: CounterData, Counter))` for precise self.

**Casts (::):** Precision tool to narrow overly generic inference — never to hide errors.

**Key mistakes:** Unsealed `any` propagation in nonstrict, sealing tables too early, unions without discriminants, annotating every local.

> Full reference: see `references/full.md`

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [TabooHarmony](https://github.com/TabooHarmony)
- **Source:** [TabooHarmony/roblox-brain](https://github.com/TabooHarmony/roblox-brain)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-tabooharmony-roblox-brain-roblox-luau-types
- Seller: https://agentstack.voostack.com/s/tabooharmony
- Browse the marketplace: https://agentstack.voostack.com/browse

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