18_pre_action_guard_skill

Overview

This skill implements a Pre-Action Guard that validates potentially destructive or irreversible actions before execution. It enforces a "measure twice, cut once" policy to prevent accidental data loss or system corruption by blocking or flagging high-risk operations.

How this skill works

The guard inspects the declared action (e.g., write_to_file, rm) and its target, evaluates them against a set of safety checks and contextual plan information, and returns a structured assessment with allowed, risk_level, reason, and warnings. It auto-blocks clear dangerous patterns (root deletions), raises sensitivity for config/env targets, and detects mixed command/output snippets to enforce command-only discipline.

When to use it

• Before any file write to an existing file
• Before running commands that include rm, del, drop, format
• When an agent proposes changes to config or environment files (.env, config)
• When plan context is available and actions must be aligned with intent
• Prior to bulk or recursive operations affecting many files or directories

Best practices

• Always provide explicit --Action and --Target parameters; return an error if missing
• Supply the current --Plan when available to enable alignment checks
• Treat CRITICAL results as blockers: stop and ask for explicit user confirmation
• Keep runnable commands isolated in clean blocks without terminal output
• Favor safe defaults (deny on ambiguity) and surface clear remediation steps in reason/warnings

Example use cases

• Agent wants to delete a directory: guard inspects target and blocks root or wildcard patterns
• Agent plans to overwrite a config file: guard flags HIGH risk and requires confirmation
• Automated deploy step proposes removing files: guard detects mixed output in snippet and rejects
• CI job attempts recursive delete: guard returns CRITICAL for patterns like /* or C:\
• Scripted migration writes new temporary files: guard marks as LOW or NONE depending on target