typescript

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha cfd30384f54c · 23 Oct 2026Report an issue or request a re-scan

• Publishergentleman-programming GitHub organizationOwner of the repository this skill is read from
• Source foldergentleman-programming/gentleman-skills/curated/typescriptThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdictcfd30384f54cA new audit runs when the source changes
• Repository statusNot archivedLast push 209 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: TypeScript strict patterns and best practices. Trigger: When writing TypeScript code - types, interfaces, generics.

---
name: typescript
description: >
  TypeScript strict patterns and best practices.
  Trigger: When writing TypeScript code - types, interfaces, generics.
license: Apache-2.0
metadata:
  author: gentleman-programming
  version: "1.0"
---

## Const Types Pattern (REQUIRED)

```typescript
// ✅ ALWAYS: Create const object first, then extract type
const STATUS = {
  ACTIVE: "active",
  INACTIVE: "inactive",
  PENDING: "pending",
} as const;

type Status = (typeof STATUS)[keyof typeof STATUS];

// ❌ NEVER: Direct union types
type Status = "active" | "inactive" | "pending";
```

**Why?** Single source of truth, runtime values, autocomplete, easier refactoring.

## Flat Interfaces (REQUIRED)

```typescript
// ✅ ALWAYS: One level depth, nested objects → dedicated interface
interface UserAddress {
  street: string;
  city: string;
}

interface User {
  id: string;
  name: string;
  address: UserAddress;  // Reference, not inline
}

interface Admin extends User {
  permissions: string[];
}

// ❌ NEVER: Inline nested objects
interface User {
  address: { street: string; city: string };  // NO!
}
```

## Never Use `any`

```typescript
// ✅ Use unknown for truly unknown types
function parse(input: unknown): User {
  if (isUser(input)) return input;
  throw new Error("Invalid input");
}

// ✅ Use generics for flexible types
function first<T>(arr: T[]): T | undefined {
  return arr[0];
}

// ❌ NEVER
function parse(input: any): any { }
```

## Utility Types

```typescript
Pick<User, "id" | "name">     // Select fields
Omit<User, "id">              // Exclude fields
Partial<User>                 // All optional
Required<User>                // All required
Readonly<User>                // All readonly
Record<string, User>          // Object type
Extract<Union, "a" | "b">     // Extract from union
Exclude<Union, "a">           // Exclude from union
NonNullable<T | null>         // Remove null/undefined
ReturnType<typeof fn>         // Function return type
Parameters<typeof fn>         // Function params tuple
```

## Type Guards

```typescript
function isUser(value: unknown): value is User {
  return (
    typeof value === "object" &&
    value !== null &&
    "id" in value &&
    "name" in value
  );
}
```

## Import Types

```typescript
import type { User } from "./types";
import { createUser, type Config } from "./utils";
```

## Keywords
typescript, ts, types, interfaces, generics, strict mode, utility types

Excerpt, first 2,438 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/gentleman-programming/gentleman-skills
git -C gentleman-skills checkout cfd30384f54c

Works in

1. 2026-10-23
   ✓SAFE B 89 / 100

   first audit · source cfd30384f54c

Questions about typescript

• github.com/gentleman-programming/gentleman-skills/tree/main/cura — the audited source at commit cfd30384f54c and every finding aboveObserved · 23 Oct 2026

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