Why It Matters

SEC359 flags Cursor rule markdown whose frontmatter sets alwaysApply to a non-boolean value.

This is useful because:

• Cursor rules are configuration-bearing markdown, not free-form prose
• non-boolean alwaysApply values are harder to reason about across tools and loaders
• the failure mode is community-hostile: the rule looks configured, but may not behave consistently

What Triggers

This rule applies only to Cursor rule markdown surfaces such as .mdc and .cursorrules.

It triggers when:

• parsed frontmatter contains alwaysApply
• and the parsed value is not a boolean

Example that triggers:

---
alwaysApply: yes
---

Examples that stay clean:

---
alwaysApply: true
---

• rules without alwaysApply
• fixture-like paths under tests/, fixtures/, examples/, or samples/

False Positives

This rule stays Preview because some repos may still carry legacy or loosely typed Cursor rule examples. The signal is about deterministic config quality and interoperability, not about exploitability.

Remediation

Set alwaysApply to an explicit boolean:

---
alwaysApply: true
---

If the rule should not always apply, use false or remove the key and rely on the normal path-based scoping model.