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

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

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):

   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:

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:

HOOK="${CLAUDE_PLUGIN_ROOT}/hooks/parity-safety-net.sh"

check() { # check <expect: block|allow> <command>
  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 — distributed by TomeVault.