2-typescript

A set of rules for writing TypeScript, a version of JavaScript that checks data types before code runs. It requires explicit types, safer error handling, reusable generic code, and defined approaches to missing values and fixed choices.

In plain words
What is it for?
Use it when designing TypeScript interfaces and types, writing generic functions, handling errors, and representing optional values or fixed alternatives.
Why use it?
It reduces unclear or unsafe data handling and makes code errors easier to find during development.

Cursor rule for Cursor

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 rules/cmnemoi/cursor-rules/2-typescript
Clone the repo
git clone --depth 1 https://github.com/cmnemoi/cursor-rules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 163 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 $0.00000 $0.00163
Opus 5 $0.00000 $0.00081
Sonnet 5 $0.00000 $0.00033
Haiku 4.5 $0.00000 $0.00016

Measured yesterday against content hash 42a940951596, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

2-typescript 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 yesterday.

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.

general-rules/.cursor/rules/02-programming-languages/2-typescript.mdc · 31 lines

What it actually says

Strict Types:

  • Type everything explicitly
  • Never use any or unknown
  • Avoid as for type conversion
  • Use type guards for assertions
  • Use generics for reusable functions

Interfaces and Types:

  • Use interface for extensible objects
  • Use type for unions and primitives

Nullability:

  • Avoid null and undefined in returns

Enumerations:

  • Prefer string literal unions to enums
  • Use const enums if needed
  • Define enum values explicitly

Lint & Error:

  • Catch errors as unknown | Error

Generics:

  • Use descriptive type parameter names
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. yesterday First seen · 31 lines · 163 tokens per session scan A 42a940951596

Subscribe to this mod's changes

2-typescript is a cursor rule published in the GitHub repository cmnemoi/cursor-rules (2 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 163 tokens. 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 2026-08-31.