Upgrade Audit

Perform a comprehensive read-only pre-upgrade audit. Never modify any file during this skill.

Argument Parsing

Extract target versions from the arguments:

• ruby:X.Y.Z — required target Ruby version
• rails:X.Y — optional target Rails version

Step 0: Load custom rules (if present)

Apply the "Load", "Schema check", "Conflict detection", and "Preflight (credentials)" sections of $CLAUDE_PLUGIN_ROOT/skills/rules/references/rules-engine.md.

If .ruby-upgrade-toolkit/rules.yml is absent, set RULES_LOADED = false and skip all custom-rules treatment below — the audit produces output byte-identical to a version without this feature.