Rails Upgrade Assistant Skill v1.0

Skill Identity

• Name: Rails Upgrade Assistant
• Version: 1.0
• Purpose: Intelligent Rails application upgrades from 7.0 through 8.1.1
• Based on: Official Rails CHANGELOGs from GitHub
• Upgrade Strategy: Sequential only (no version skipping)

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Core Functionality

This skill helps users upgrade Rails applications through a sequential three-step process:

Step 1: Breaking Changes Detection Script

• Claude generates executable bash script tailored to the specific upgrade
• Script scans user's codebase for breaking changes
• Finds issues with file:line references
• Generates findings report (TXT file)
• Runs in < 30 seconds
• Lists affected files for Neovim integration

Step 2: User Runs Script & Shares Findings

• User executes the detection script in their project directory
• Script outputs rails_{version}_upgrade_findings.txt
• User shares findings report back with Claude

Step 3: Claude Generates Reports Based on Actual Findings

• Comprehensive Upgrade Report: Breaking changes analysis with OLD vs NEW code examples, custom code warnings with ⚠️ flags, step-by-step migration plan, testing checklist and rollback plan
• app:update Preview Report: Shows exact configuration file changes (OLD vs NEW), lists new files to be created, impact assessment (HIGH/MEDIUM/LOW), Neovim buffer list ready

User Benefits:

• ⏱️ Saves 2-3 hours per upgrade (automated detection)
• 🎯 90%+ accuracy in finding breaking changes
• 📋 Clear file:line references for every issue
• 🚀 Reports based on ACTUAL detected issues, not hypothetical
• 📊 50% faster upgrades overall

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Trigger Patterns

Claude should activate this skill when user says:

Initial Upgrade Requests (Generate Detection Script):

• "Upgrade my Rails app to [version]"
• "Help me upgrade from Rails [x] to [y]"
• "What breaking changes are in Rails [version]?"
• "Plan my upgrade from [x] to [y]"
• "What Rails version am I using?"
• "Analyze my Rails app for upgrade"
• "Create a detection script for Rails [version]"
• "Generate a breaking changes script"
• "Find breaking changes in my code"

After Script Execution (Generate Reports):

• "Here's my findings.txt"
• "I ran the script, here are the results"
• "The detection script found [X] issues"
• "Can you analyze these findings?"
• User shares/uploads findings.txt file

Specific Report Requests (Only After Findings Shared):

• "Show me the app:update changes"
• "Preview configuration changes for Rails [version]"
• "Generate the upgrade report"
• "Create the comprehensive report"

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CRITICAL: 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

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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

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MCP Tools Integration

Required: Rails MCP Server

Tools:

• railsMcpServer:project_info - Get Rails version, structure, API mode
• railsMcpServer:get_file - Read file contents
• railsMcpServer:list_files - Browse directories
• railsMcpServer:analyze_environment_config - Config files

Optional: Neovim MCP Server

Tools:

• nvimMcpServer:get_project_buffers - List open files
• nvimMcpServer:update_buffer - Update file content

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High-Level Workflow

When user requests an upgrade, follow this workflow:

Step 1: Detect Current Version

1. Call: railsMcpServer:project_info
2. Store: current_version, target_version, project_type, project_root

Step 2: Load Detection Script Resources

1. Read: detection-scripts/patterns/rails-{VERSION}-patterns.yml
2. Read: detection-scripts/templates/detection-script-template.sh
3. Read: workflows/detection-script-workflow.md (for generation instructions)

Step 3: Generate Detection Script

1. Follow workflow in detection-script-workflow.md
2. Generate version-specific bash script
3. Deliver script to user
4. Instruct user to run script and share findings.txt

Step 4: Wait for User to Run Script

User runs: ./detect_rails_{version}_breaking_changes.sh
Script outputs: rails_{version}_upgrade_findings.txt
User shares findings back with Claude

Step 5: Load Report Generation Resources

1. Read: templates/upgrade-report-template.md
2. Read: version-guides/upgrade-{FROM}-to-{TO}.md
3. Read: templates/app-update-preview-template.md
4. Read: workflows/upgrade-report-workflow.md
5. Read: workflows/app-update-preview-workflow.md

Step 6: Analyze User's Actual Findings

1. Parse the findings.txt file
2. Extract detected breaking changes and affected files
3. Read user's actual config files for context
4. Identify custom code patterns from findings

Step 7: Generate Reports Based on Findings

Deliverable #1: Comprehensive Upgrade Report

• Workflow: See workflows/upgrade-report-workflow.md
• Input: Actual findings from script + version guide data
• Output: Report with real code examples from user's project

Deliverable #2: app:update Preview

• Workflow: See workflows/app-update-preview-workflow.md
• Input: Actual config files + findings
• Output: Preview with real file paths and changes

Step 8: Present Reports

1. Present Comprehensive Upgrade Report first
2. Present app:update Preview Report second
3. Explain next steps
4. Offer interactive help with Neovim (if available)

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When to Load Detailed Workflows

Load workflow files when you need detailed instructions:

Step 1 - Load Before Generating Detection Script:

• workflows/detection-script-workflow.md - Before creating detection scripts

Step 2 - User Runs Script (No Claude action needed)

Step 3 - Load Before Generating Reports (After receiving findings):

• workflows/upgrade-report-workflow.md - Before creating upgrade reports
• workflows/app-update-preview-workflow.md - Before creating previews

Load When User Needs Examples:

• examples/simple-upgrade.md - User asks about simple upgrades
• examples/multi-hop-upgrade.md - User asks about complex upgrades
• examples/detection-script-only.md - User wants only detection script
• examples/preview-only.md - User wants only preview

Load When You Need Reference:

• reference/pattern-file-guide.md - When processing YAML pattern files
• reference/quality-checklist.md - Before delivering any output
• reference/troubleshooting.md - When encountering issues

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Quality Checklist

Before delivering, verify:

For Detection Script:

• All {PLACEHOLDERS} replaced with actual values
• Patterns match target Rails version
• Script includes all breaking changes from pattern file
• File paths use user's actual project structure
• User instructions are clear

After User Runs Script (Before Generating Reports):

• Received and parsed findings.txt from user
• Identified all detected breaking changes
• Collected affected file paths
• Noted custom code warnings from findings

For Comprehensive Upgrade Report:

• All {PLACEHOLDERS} replaced with actual values
• Used ACTUAL findings from script (not generic examples)
• Breaking changes section includes real file:line references
• Custom code warnings based on actual detected issues
• Code examples use user's actual code from affected files
• Next steps clearly outlined

For app:update Preview:

• All {PLACEHOLDERS} replaced with actual values
• File list matches user's actual config files
• Diffs based on real current config vs target version
• Neovim buffer list includes only affected files
• Next steps clearly outlined

Detailed Checklist: See reference/quality-checklist.md

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Common Request Patterns

Pattern 1: Full Upgrade Request

User says: "Upgrade my Rails app to 8.1"

Action - Phase 1 (Generate Script):

1. Load: workflows/detection-script-workflow.md
2. Generate detection script
3. Deliver script with instructions to run it
4. Wait for user to share findings.txt

Action - Phase 2 (Generate Reports):

1. Parse findings.txt
2. Load: workflows/upgrade-report-workflow.md
3. Load: workflows/app-update-preview-workflow.md
4. Generate Comprehensive Upgrade Report (using actual findings)
5. Generate app:update Preview (using actual findings)
6. Reference: examples/simple-upgrade.md for structure

Pattern 2: Multi-Hop Request

User says: "Help me upgrade from Rails 7.0 to 8.1"

Action:

1. Explain sequential requirement
2. Reference: examples/multi-hop-upgrade.md
3. Follow Pattern 1 for FIRST hop (7.0 → 7.1)
4. After first hop complete, repeat for next hops

Pattern 3: Detection Script Only

User says: "Create a detection script for Rails 8.0"

Action:

1. Load: workflows/detection-script-workflow.md
2. Generate detection script only
3. Reference: examples/detection-script-only.md
4. Do NOT generate reports yet (wait for findings)

Pattern 4: User Returns with Findings

User says: "Here's my findings.txt" or shares script output

Action:

1. Parse findings.txt
2. Load: workflows/upgrade-report-workflow.md
3. Load: workflows/app-update-preview-workflow.md
4. Generate Comprehensive Upgrade Report
5. Generate app:update Preview

Pattern 5: Preview Only (After Findings Shared)

User says: "Show me the app:update changes for Rails 7.2"

Action:

1. Check if user has shared findings
2. If yes: Load workflows/app-update-preview-workflow.md and generate
3. If no: Ask user to run detection script first
4. Reference: examples/preview-only.md

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Key Principles

1. Always Generate Detection Script First (unless user only wants reports and has findings)
2. Wait for User to Run Script (reports depend on actual findings)
3. Always Use Actual Findings (no generic examples in reports)
4. Always Flag Custom Code (with ⚠️ warnings based on detected issues)
5. Always Use Templates (for consistency)
6. Always Check Quality (before delivery)
7. Load Workflows as Needed (don't hold everything in memory)
8. Sequential Process is Critical (script → findings → reports)

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File Organization

This skill follows a modular structure:

rails-upgrade-assistant/
├── SKILL.md                          # This file (high-level)
├── workflows/                        # Detailed how-to guides
│   ├── upgrade-report-workflow.md
│   ├── detection-script-workflow.md
│   └── app-update-preview-workflow.md
├── examples/                         # Usage examples
│   ├── simple-upgrade.md
│   ├── multi-hop-upgrade.md
│   ├── detection-script-only.md
│   └── preview-only.md
├── reference/                        # Reference documentation
│   ├── pattern-file-guide.md
│   ├── quality-checklist.md
│   └── troubleshooting.md
├── version-guides/                   # Version-specific guides
├── templates/                        # Report templates
└── detection-scripts/                # Pattern files and templates

When to Load What:

• Load workflows/ when generating deliverables
• Load examples/ when user needs clarification
• Load reference/ when you need detailed guidance

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Success Criteria

A successful upgrade assistance session:

✅ Generated detection script (Phase 1)
✅ User ran script and shared findings.txt (Phase 2)
✅ Generated Comprehensive Upgrade Report using actual findings (Phase 3)
✅ Generated app:update Preview using actual findings (Phase 3)
✅ Used user's actual code from findings (not generic examples)
✅ Flagged all custom code with ⚠️ warnings based on detected issues
✅ Provided clear next steps
✅ Offered interactive help (if Neovim available)

Verification: See reference/quality-checklist.md

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Version: 1.0
Last Updated: November 2, 2025
Skill Type: Modular with external workflows and examples