20-security-privacy

A set of rules for code involving login systems, secrets, personal information, input checks, or other security-sensitive data. It covers protecting credentials, validating input, and keeping sensitive values out of logs.

In plain words
What is it for?
Use it when handling API keys, passwords, tokens, user data, external input, authentication, or potentially destructive security changes.
Why use it?
It reduces the risk of exposing secrets or personal information and requires a pause before changes that could cause data loss or break compatibility.

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/luxvil/ai-coding-rules/20-security-privacy
Clone the repo
git clone --depth 1 https://github.com/Luxvil/ai-coding-rules

Made for: Cursor.

Per session 138 This file is loaded in full into every session.
When invoked 138 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00138 $0.00138
Opus 5 $0.00069 $0.00069
Sonnet 5 $0.00028 $0.00028
Haiku 4.5 $0.00014 $0.00014

Measured 2d ago against content hash aa5e0effd42b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

20-security-privacy 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.

Origin

This is a copy

100% identical to 20-security-privacy — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/20-security-privacy.mdc · 24 lines

What it actually says

Security & Privacy Rules

Secrets & Credentials

  • Never hard‑code API keys, passwords, or tokens.
  • Use environment variables or secret managers.

Input Validation

  • Validate all external input (Zod/Pydantic or equivalent).
  • Reject/normalize unexpected fields.

Logging

  • Never log PII or secrets.
  • Scrub sensitive values before logging.

Safety Stops

  • If a change can cause data loss or a breaking change, stop and ask.
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 · 24 lines · 138 tokens per session scan A aa5e0effd42b

Subscribe to this mod's changes

20-security-privacy is a cursor rule published in the GitHub repository Luxvil/ai-coding-rules (3 stars, last pushed 3d ago), licensed MIT. It adds 138 tokens to every session, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to 20-security-privacy, differing in 0 lines, and is treated as a copy.