TypeScript

TypeScript (strict) rules for Cursor

Strict typing rules that stop agents from reaching for any, non-null assertions and unchecked casts.

The rule

Save as .cursor/rules/typescript.mdc. Cursor picks it up on the next request.

.cursor/rules/typescript.mdc

---
description: TypeScript style and safety rules
globs: **/*.ts, **/*.tsx
alwaysApply: false
---

- No `any`. Use `unknown` and narrow, or write the real type.
- No non-null assertions (`!`) and no `as` casts to silence errors; fix the type instead.
- Prefer `type` aliases and discriminated unions over class hierarchies.
- Validate external input (HTTP bodies, env vars, JSON files) with a schema library at the boundary.
- Exported functions declare their return type.
- Run the typechecker before finishing; do not leave new type errors.

How Cursor loads this rule

Read from the frontmatter above, per Cursor's rules documentation.

  • alwaysApply: false with globs: **/*.ts, **/*.tsx: attached automatically when a matching file is in context.
  • Keep the .mdc extension. A plain .md file in .cursor/rules is ignored by the rules system.
  • Prefer to generate your own? Type /create-rule in Agent and describe what you want; Cursor saves the file to .cursor/rules.
  • Team Rules come first, then Project Rules like this one, then User Rules. Earlier sources win when guidance conflicts.

Cursor rules setup guideCursor Team RulesLet Cursor run commands without asking

Using another agent too?

The same instructions work as plain Markdown in AGENTS.md, which Codex, Gemini CLI, GitHub Copilot and most other coding agents read.

AGENTS.md (section)

## TypeScript (strict)

- No `any`. Use `unknown` and narrow, or write the real type.
- No non-null assertions (`!`) and no `as` casts to silence errors; fix the type instead.
- Prefer `type` aliases and discriminated unions over class hierarchies.
- Validate external input (HTTP bodies, env vars, JSON files) with a schema library at the boundary.
- Exported functions declare their return type.
- Run the typechecker before finishing; do not leave new type errors.

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Get Cursor rules and settings changes by email

When Cursor changes how rules, run modes or settings work, we update these templates from the docs and send a short note. One email a week at most.

Reviewed Oct 17, 2026. Written by AgentAtlas. Adapt it to your codebase before relying on it.