SG-080: Skill argument injection into preprocessor shell
Severity: HIGH
Preprocessor block `!`...`` uses `$N` substitution with user-supplied arguments without shell escaping.
Fires when
- Skill body has a `!`...`` preprocessor block that substitutes user-supplied `$1`-`$9` arguments.
- The `$N` substitution is unescaped, so a user argument can inject shell commands into the preprocessor run.
Remediation
No safe remediation: a file that triggers this rule should be rejected, not patched. Read the flagged lines in the source before deciding.