CursorCodingbeginner

Cursor project rules must be .mdc files, or they're ignored

Rules in .cursor/rules need the .mdc extension plus frontmatter. A plain .md file there is silently skipped; use AGENTS.md for plain markdown.

Cursor’s docs spell it out: project rules live in .cursor/rules/ and must use the .mdc extension. A plain .md in that folder is ignored because it has no frontmatter.

The frontmatter decides when a rule applies

---
description: When to apply this rule (used for "Apply Intelligently")
globs: src/api/**/*.ts
alwaysApply: false
---
  • alwaysApply: true: every chat. Use sparingly.
  • globs: auto-attached when matching files are in context.
  • description only: the agent decides based on relevance.
  • None: only when you @-mention the rule.

Prefer plain markdown? Put instructions in AGENTS.md instead.

Sources

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