security

A repository rule that checks for private, sensitive, or confidential files before changes are staged or committed. Protected locations are configured in the repository settings.

In plain words
What is it for?
It helps inspect changed and staged files, compare them with configured protected paths, and stop the commit when a protected file is found.
Why use it?
It reduces the chance of committing files that should remain out of version control.

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/markmhendrickson/foundation/security
Clone the repo
git clone --depth 1 https://github.com/markmhendrickson/foundation

Made for: Cursor.

Per session 31 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,297 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 $0.00031 $0.01297
Opus 5 $0.00015 $0.00648
Sonnet 5 $0.00006 $0.00259
Haiku 4.5 $0.00003 $0.00130

Measured yesterday against content hash 6e61331ec284, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security 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 yesterday.

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.

.cursor/rules/security.mdc · 159 lines

How it starts

The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security Rule

Prevents accidental commits of private, sensitive, or confidential documentation and data.

Configuration: This rule uses protected paths configured in foundation-config.yaml under security.pre_commit_audit.protected_paths.

Pre-Commit Security Audit

Before staging or committing ANY changes, agents MUST perform the following checks:

1. Protected Paths Check

Check for any files in protected paths (configured in foundation-config.yaml):

# Load protected paths from config (example paths shown)
PROTECTED_PATHS=("docs/private/" "data/")  # Configured per repository

# Check unstaged changes
for path in "${PROTECTED_PATHS[@]}"; do
  if git status --porcelain | grep -E "^[AM]|^\?\?" | grep -qE "$path"; then
    echo "❌ SECURITY VIOLATION: Files in $path detected!"
    git status --porcelain | grep -E "^[AM]|^\?\?" | grep "$path"
    exit 1
  fi
done

# Check staged changes (if any exist)
for path in "${PROTECTED_PATHS[@]}"; do
  if git diff --cached --name-only 2>/dev/null | grep -qE "$path"; then
    echo "❌ SECURITY VIOLATION: Files in $path already staged!"
    git diff --cached --name-only | grep "$path"
    exit 1
  fi
done

If any files match protected paths, ABORT the commit immediately and alert the user.

2. Environment Files Check

Check for any .env* files (should be in .gitignore but verify):

if git status --porcelain | grep -qE "\.env"; then
  echo "❌ SECURITY VIOLATION: .env files detected!"
  git status --porcelain | grep "\.env"
  exit 1
fi

if git diff --cached --name-only 2>/dev/null | grep -qE "\.env"; then
  echo "❌ SECURITY VIOLATION: .env files already staged!"
  git diff --cached --name-only | grep "\.env"
  exit 1
fi

If any .env* files are detected, ABORT the commit.

Configuration: Enable/disable via security.pre_commit_audit.check_env_files in foundation-config.yaml.

3. Sensitive File Pattern Check

Check for files with sensitive naming patterns:

# Check for files with "secret" or "private" in path (excluding legitimate code)
git status --porcelain | grep -vE "(test|spec|property_keys)" | grep -iE "(secret|private)" | grep -vE "$(IFS='|'; echo "${PROTECTED_PATHS[*]}")" && echo "WARNING: Suspicious file patterns detected" && exit 1

Read the full file on GitHub · 159 lines

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. yesterday First seen · 159 lines · 31 tokens per session scan A 6e61331ec284

Subscribe to this mod's changes

security is a cursor rule published in the GitHub repository markmhendrickson/foundation (2 stars, last pushed 1mo ago), licensed MIT. It adds 31 tokens to every session and 1,297 once invoked, about $0.0002 per session on Opus 5. 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 2026-08-31.