invalid-rule

A rule with invalid frontmatter, the metadata at the top of a rule file, because it combines always-apply behavior with non-empty file patterns.

In plain words
What is it for?
Testing linting of rules whose automatic-application settings and file patterns conflict.
Why use it?
It provides a case for detecting and reporting invalid rule configuration during linting.

Cursor rule

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/zackiles/cursor-config/invalid-rule
Clone the repo
git clone --depth 1 https://github.com/zackiles/cursor-config
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 40 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 $0.00040
Opus 5 $0.00000 $0.00020
Sonnet 5 $0.00000 $0.00008
Haiku 4.5 $0.00000 $0.00004

Measured 2d ago against content hash 187da9021c2a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

invalid-rule 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 2d ago.

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.

test/mocks/failing-rules/invalid-rule.mdc · 9 lines

What it actually says

Invalid Rule

This rule has invalid frontmatter that should fail linting because when alwaysApply is true, globs should be empty.

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. 2d ago First seen · 9 lines · 0 tokens per session scan A 187da9021c2a

Subscribe to this mod's changes

invalid-rule is a cursor rule published in the GitHub repository zackiles/cursor-config (17 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 40 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 2026-08-30.