# Parity Safety Net Rules > View, set, and verify the custom guard rules enforced by Lisa's safety-net PreToolUse Bash hook (parity-safety-net.sh). The consolidated cross-agent equivalent of the upstream safety-net plugin's set-custom-rules + verify-custom-rules skills — manages a project-local list of extended-regex patterns that block destructive shell commands, on Codex, agy, Copilot, Cursor, and Claude. Use when this capability is needed. - Skill: `tomevault-io/parity-safety-net-rules` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/parity-safety-net-rules` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/parity-safety-net-rules/raw - Safety review: pending (external: skill-scanner PASS, skillspector CAUTION) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/parity-safety-net-rules --- # Parity Safety-Net Rules Manage the **custom guard rules** that Lisa's safety-net hook enforces on every Bash command. The hook (`hooks/parity-safety-net.sh`, registered as a `PreToolUse` matcher on `Bash`) ships with built-in guards against catastrophic commands; this skill lets a project **view**, **set**, and **verify** *additional* project-specific rules on top of those built-ins. > **Lisa-native reimplementation.** This consolidates the upstream > `safety-net@cc-marketplace` plugin's two rule-management skills > (`set-custom-rules` + `verify-custom-rules`) into one. It is reimplemented from > scratch against Lisa conventions — it does **not** port or invoke upstream > plugin code. > > **Drift tracking.** Pinned to `safety-net@cc-marketplace@0.9.0`. > `scripts/plugin-parity-drift.mjs` compares this pin against the upstream > version in the plugin cache and flags staleness. **Do not port or copy upstream > plugin code.** ## How the rules work - The hook always enforces its **built-in guards** (see below). These cannot be disabled from the rules file — they are the floor. - **Custom rules** live in a project-local file, one **POSIX extended regular expression (ERE)** per line. Blank lines and lines beginning with `#` are ignored. Matching is case-insensitive (`grep -Ei`). - If *any* built-in guard or custom rule matches the proposed command, the hook exits non-zero and the Bash call is **blocked**, with the reason shown to the agent. ### Rules file location Resolved in this order: 1. `$SAFETY_NET_RULES_FILE` (explicit override), else 2. `${CLAUDE_PROJECT_DIR:-$PWD}/.claude/safety-net-rules.txt` ```bash RULES_FILE="${SAFETY_NET_RULES_FILE:-${CLAUDE_PROJECT_DIR:-$PWD}/.claude/safety-net-rules.txt}" ``` ### Built-in guards (always on) 1. `rm -rf` of a filesystem root, `$HOME`/`~`, or a top-level wildcard. 2. Force-pushing a protected branch (`main`/`master`/`production`/`release`). `--force-with-lease` is intentionally allowed. 3. `git reset --hard` while the working tree is **dirty** (would discard work). 4. Destructive SQL — `DROP DATABASE/SCHEMA/TABLE`, `TRUNCATE TABLE`. ## View the current rules ```bash RULES_FILE="${SAFETY_NET_RULES_FILE:-${CLAUDE_PROJECT_DIR:-$PWD}/.claude/safety-net-rules.txt}" if [ -f "$RULES_FILE" ]; then echo "Custom safety-net rules ($RULES_FILE):" grep -vE '^[[:space:]]*(#|$)' "$RULES_FILE" || echo "(no active rules)" else echo "No custom rules file yet ($RULES_FILE). Only built-in guards are active." fi ``` `Read` the file to show comments and structure as well. ## Set (add or edit) a rule A rule is an ERE matched against the full command string. Keep rules **specific** to avoid blocking legitimate work — anchor on the dangerous verb and its target. 1. Ensure the file exists, then **append** a commented rule (use `Edit`/`Write`, or append from the shell): ```bash RULES_FILE="${SAFETY_NET_RULES_FILE:-${CLAUDE_PROJECT_DIR:-$PWD}/.claude/safety-net-rules.txt}" mkdir -p "$(dirname "$RULES_FILE")" { echo "# Block deleting a Kubernetes namespace" echo 'kubectl[[:space:]]+delete[[:space:]]+namespace' } >> "$RULES_FILE" ``` 2. **Always verify** the new rule (next section) before considering it set — confirm it blocks what it should and allows what it shouldn't. Editing/removing: open the file with `Edit` and change or delete the line. Removing a rule never affects the built-in guards. ## Verify the rules Two checks — both should pass before you trust a rule. ### 1. The ERE is valid An invalid regex would make the hook error on every command. Validate it: ```bash printf '%s' "$RULE" | grep -Eq -- "$RULE" 2>/dev/null && echo "valid ERE" \ || echo "INVALID ERE — fix before saving" ``` ### 2. The rule behaves as intended Drive the **actual hook** with a fake `PreToolUse` payload and assert the exit code (non-zero = blocked, 0 = allowed). Build the JSON with `jq` so the test command line itself never contains the dangerous literal: ```bash HOOK="${CLAUDE_PLUGIN_ROOT}/hooks/parity-safety-net.sh" check() { # check jq -nc --arg c "$2" '{tool_name:"Bash",tool_input:{command:$c}}' \ | bash "$HOOK" >/dev/null 2>&1 local code=$? local got=allow; [ "$code" -ne 0 ] && got=block printf '%-5s want=%-5s got=%-5s %s\n' \ "$([ "$got" = "$1" ] && echo OK || echo FAIL)" "$1" "$got" "$2" } # Should block (matches the new rule): check block "kubectl delete namespace prod" # Should allow (must not over-match): check allow "kubectl get pods" ``` Report a table of cases with want/got/verdict. If any case disagrees, tighten the ERE and re-verify. ## Rules - **Built-in guards are the floor** — custom rules only *add* blocks; they cannot weaken the built-ins. - **Prefer specific over broad** — a rule that blocks too much trains users to bypass the safety net. Anchor on verb + target. - **Verify every rule against the real hook** before saving — never ship an unverified or syntactically invalid ERE. - **Never weaken the net to unblock yourself.** If a built-in guard fires on a command that is genuinely safe, run it manually outside the agent after the user confirms — do not edit the hook to remove the guard. --- > Source: [CodySwannGT/lisa](https://github.com/CodySwannGT/lisa) — distributed by [TomeVault](https://tomevault.io).