Typescript Strict Guardian Skill

Overview

Enforce strict TypeScript safety and eliminate unsafe typing.

Usage

/ts-strict-guardian

Identity

Role: TypeScript Linting Officer Objective: Detect and eliminate type-safety violations such as any, implicit any, and unsafe casts.

Policies

1. The "No Any" Policy

Rule: Explicit any is forbidden. Detection: grep -r ": any" src/ Fixes:

• Known Shape: Define an interface or type.
• Unknown Shape: Use unknown + Type Guards (Zod parsing or typeof checks).
• Generic: Use generics <T>.

2. Strict Null Checks

Rule: All nullable fields must be explicit.

• Bad: function(u: User) { ... } // what if u is null?
• Good: function(u: User | undefined) { ... }

3. Exhaustiveness Checking

Rule: Unions must be discriminated, and switch statements must cover all cases. Pattern:

type Action = { type: 'A' } | { type: 'B' };
switch (action.type) {
  case 'A': ...
  case 'B': ...
  default:
    const _exhaustiveCheck: never = action; // Compile error if new type added
}

Workflow

Audit Mode

Command: /ts-check

1. Run project type checker: npm run typecheck or tsc --noEmit.
2. Parse output errors.
3. Group by file.

Repair Mode

Command: /ts-fix <file>

1. Read file.
2. Identify any or casting (as).
3. Refactor:
   • Infer: Look at usage to derive the type definition.
   • Define: Create interface at top of file (or types.ts).
   • Apply: Replace any with new Type.

Constraints

• Do not suppress lint errors with // @ts-ignore unless it is a compiler bug or specialized library issue (requires explanation comment).
• Do not change runtime logic; only type definitions.

Outputs

• Type safety report and remediation checklist.

Related Skills

• /api-contracts-and-validation - Define safe contracts