Rails Upgrade Assistant

Rails Upgrade Assistant Skill v1.0

How It Works

Three-step process:

1. Detection Script — Generate a bash script that scans the codebase for breaking changes with file:line references
2. User Runs Script — User executes it, gets rails_{version}_upgrade_findings.txt
3. Reports — Generate upgrade report and app:update preview based on actual findings (not hypothetical)

Sequential Upgrade Strategy

⚠️ Version Skipping is NOT Allowed

Rails upgrades MUST follow this exact sequence:

7.0.x → 7.1.x → 7.2.x → 8.0.x → 8.1.x

You CANNOT skip versions. Examples:

• ❌ 7.0 → 7.2 (skips 7.1)
• ❌ 7.0 → 8.0 (skips 7.1 and 7.2)
• ✅ 7.0 → 7.1 (correct)
• ✅ 7.1 → 7.2 (correct)

If user requests a multi-hop upgrade (e.g., 7.0 → 8.1):

1. Explain the sequential requirement
2. Break it into individual hops
3. Generate separate reports for each hop
4. Recommend completing each hop fully before moving to next

Available Resources

Core Documentation

• docs/README.md - Human-readable overview
• docs/QUICK-REFERENCE.md - Command cheat sheet
• docs/USAGE-GUIDE.md - Comprehensive how-to

Version-Specific Guides (Load as needed)

• version-guides/upgrade-7.0-to-7.1.md - Rails 7.0 → 7.1
• version-guides/upgrade-7.1-to-7.2.md - Rails 7.1 → 7.2
• version-guides/upgrade-7.2-to-8.0.md - Rails 7.2 → 8.0
• version-guides/upgrade-8.0-to-8.1.md - Rails 8.0 → 8.1

Workflow Guides (Load when generating deliverables)

• workflows/upgrade-report-workflow.md - How to generate upgrade reports
• workflows/detection-script-workflow.md - How to generate detection scripts
• workflows/app-update-preview-workflow.md - How to generate app:update previews

Examples (Load when user needs clarification)

• examples/simple-upgrade.md - Single-hop upgrade example
• examples/multi-hop-upgrade.md - Multi-hop upgrade example
• examples/detection-script-only.md - Detection script only request
• examples/preview-only.md - Preview only request

Reference Materials

• reference/breaking-changes-by-version.md - Quick lookup
• reference/multi-hop-strategy.md - Multi-version planning
• reference/deprecations-timeline.md - Deprecation tracking
• reference/testing-checklist.md - Comprehensive testing
• reference/pattern-file-guide.md - How to use pattern files
• reference/quality-checklist.md - Pre-delivery verification
• reference/troubleshooting.md - Common issues and solutions

Detection Script Resources

• detection-scripts/patterns/rails-72-patterns.yml - Rails 7.2 patterns
• detection-scripts/patterns/rails-80-patterns.yml - Rails 8.0 patterns
• detection-scripts/patterns/rails-81-patterns.yml - Rails 8.1 patterns
• detection-scripts/templates/detection-script-template.sh - Bash template

Report Templates

• templates/upgrade-report-template.md - Main upgrade report structure
• templates/app-update-preview-template.md - Configuration preview

Workflow

Phase 1: Generate Detection Script

1. Detect current Rails version from Gemfile.lock
2. Read detection-scripts/patterns/rails-{VERSION}-patterns.yml
3. Read detection-scripts/templates/detection-script-template.sh
4. Read workflows/detection-script-workflow.md
5. Generate version-specific bash script and deliver to user

Phase 2: User Runs Script

User runs the script, gets findings. Wait for them to share rails_{version}_upgrade_findings.txt.

Phase 3: Generate Reports

1. Parse findings.txt — extract breaking changes and affected files
2. Read version-guides/upgrade-{FROM}-to-{TO}.md
3. Read workflows/upgrade-report-workflow.md and workflows/app-update-preview-workflow.md
4. Generate Comprehensive Upgrade Report with real code from the user's project
5. Generate app:update Preview with actual config file diffs

Quality

Before delivering any output, verify against reference/quality-checklist.md. Key rules:

• Replace all {PLACEHOLDERS} with actual values
• Use ACTUAL findings from the script, not generic examples
• Include real file:line references and real code from the user's project
• Flag custom code with warnings

Bundled Resources

Load these as needed — don't read everything upfront: