Rails Upgrade

Organization

ombulabs

rails-upgrade

Analyzes Rails applications and generates comprehensive upgrade reports with breaking changes, deprecations, and step-by-step migration guides for Rails 2.3 through 8.1. Use when upgrading Rails applications, planning multi-hop upgrades, querying version-specific changes, or answering what stands between the app and the next Rails version. Based on FastRuby.io methodology and "The Complete Guide to Upgrade Rails" ebook.

Overview

Publisher	ombulabs
Repository	`claude-code_rails-upgrade-skill`
Skill name	`rails-upgrade`
Stars	393
Forks	19
Bundled files	68
License	MIT
Links	Skill source Repository Homepage

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
68 bundled files
Scripts, templates, and references the model can read while it works. Files are read-only and never executed.
Open source
Published by ombulabs on GitHub. Read the source before you install it.

Installation

Install the Rails Upgrade AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/ombulabs/claude-code_rails-upgrade-skill/tree/main/rails-upgrade
Enable the skill in any chat where you want it available.

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/ombulabs/claude-code_rails-upgrade-skill.git /tmp/claude-code_rails-upgrade-skill
mkdir -p .claude/skills
cp -r /tmp/claude-code_rails-upgrade-skill/rails-upgrade .claude/skills/rails-upgrade

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Rails Upgrade in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Rails Upgrade on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Rails Upgrade is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Rails Upgrade Assistant Skill

Skill Identity

Name: Rails Upgrade Assistant
Purpose: Intelligent Rails application upgrades from 2.3 through 8.1
Skill Type: Modular with external workflows and examples
Upgrade Strategy: Sequential only (no version skipping)
Methodology: Based on FastRuby.io upgrade best practices and "The Complete Guide to Upgrade Rails" ebook
Attribution: Content based on "The Complete Guide to Upgrade Rails" by FastRuby.io (OmbuLabs)

Terminology

Term	Meaning	Where
Workflow	One numbered unit of the upgrade flow, one file	`workflows/<NN>-<name>-workflow.md`
Step	A `Step N` header inside a workflow file	inside the workflow
Reference	Material loaded on demand: lookup tables, playbooks, conditional branches	`references/<name>-reference.md`

No sub-steps: a "Step 4.1" is either two sequential steps or a conditional branch inside one step (### A. / ### B. headers). Refer to a whole workflow as Workflow NN; refer to a step as file path plus step, e.g. workflows/01-run-test-suite-workflow.md Step 4. Not used in headings: Stage, Phase, Sub-step, dotted step numbers.

Dependencies

dual-boot skill (github.com/ombulabs/claude-code_dual-boot-skill) — Sets up and manages dual-boot environments using the next_rails gem. Covers setup, NextRails.next? code patterns, CI configuration, and post-upgrade cleanup. Must be installed for Workflow 04.
- Workflow 04 file: workflows/04-setup-next-rails-workflow.md
rails-load-defaults skill (github.com/ombulabs/claude-code_rails-load-defaults-skill) — Handles incremental load_defaults updates with tiered risk assessment (Tier 1: low-risk, Tier 2: needs codebase grep, Tier 3: requires human review). Used as the final step after the Rails version upgrade is complete.

Core Methodology (FastRuby.io Approach)

This skill follows the proven FastRuby.io upgrade methodology:

Incremental Upgrades - Always upgrade one minor/major version at a time
Assessment First - Understand scope before making changes
Dual-Boot Testing - Test both versions during transition using next_rails gem
Test Coverage - Ensure adequate test coverage before upgrading (aim for 80%+)
Gem Compatibility - Check gem compatibility at each step using RailsBump
Deprecation Warnings - Address deprecations before upgrading
Backwards Compatible Changes - Deploy small changes to production before version bump

Key Resources:

DELEGATE to the dual-boot skill for dual-boot setup with next_rails (see Dependencies)
See references/deprecation-warnings-reference.md for managing deprecations
See references/staying-current-reference.md for maintaining upgrades over time

CRITICAL: Dual-Boot Code Pattern with `NextRails.next?`

When proposing code fixes that must work with both the current and target Rails versions (dual-boot), always use NextRails.next? from the next_rails gem — never use respond_to? or other feature-detection patterns.

DELEGATE to the dual-boot skill for:

Setup and initialization (next_rails --init, Gemfile.next)
NextRails.next? code patterns and examples
CI configuration for dual-boot testing
Post-upgrade cleanup (removing dual-boot branches)

DEPENDENCY: Requires the dual-boot skill

Available Resources

Core Documentation

SKILL.md - This file (entry point)

Version-Specific Guides (Load as needed)

Legacy Rails:

version-guides/upgrade-3.2-to-4.0.md - Rails 3.2 → 4.0 (Strong Parameters)
version-guides/upgrade-4.0-to-4.1.md - Rails 4.0 → 4.1 (Spring, secrets.yml, enums)
version-guides/upgrade-4.1-to-4.2.md - Rails 4.1 → 4.2 (ActiveJob, Web Console)
version-guides/upgrade-4.2-to-5.0.md - Rails 4.2 → 5.0 (ApplicationRecord)

Modern Rails:

version-guides/upgrade-5.0-to-5.1.md - Rails 5.0 → 5.1 (Encrypted secrets)
version-guides/upgrade-5.1-to-5.2.md - Rails 5.1 → 5.2 (Active Storage, Credentials)
version-guides/upgrade-5.2-to-6.0.md - Rails 5.2 → 6.0 (Zeitwerk)
version-guides/upgrade-6.0-to-6.1.md - Rails 6.0 → 6.1 (Horizontal sharding)
version-guides/upgrade-6.1-to-7.0.md - Rails 6.1 → 7.0 (Hotwire/Turbo)
version-guides/upgrade-7.0-to-7.1.md - Rails 7.0 → 7.1 (Composite keys)
version-guides/upgrade-7.1-to-7.2.md - Rails 7.1 → 7.2 (Transaction jobs)
version-guides/upgrade-7.2-to-8.0.md - Rails 7.2 → 8.0 (Propshaft)
version-guides/upgrade-8.0-to-8.1.md - Rails 8.0 → 8.1 (bundler-audit)

Examples (Load when user needs clarification)

examples/simple-upgrade.md - Single-hop upgrade example
examples/multi-hop-upgrade.md - Multi-hop upgrade example

External Dependencies

dual-boot skill - Dual-boot setup and management with next_rails (Workflow 04) (https://github.com/ombulabs/claude-code_dual-boot-skill)
rails-load-defaults skill - Incremental load_defaults alignment (Workflow 12) (https://github.com/ombulabs/claude-code_rails-load-defaults-skill)
upgrade-cleanup companion plugin - User-triggered. Removes dual-boot scaffolding and drops NextRails.next? / NextRails.current? branches. Deprecation triage stays with this skill for the next hop.

Reference Materials

references/sequential-strategy-reference.md - Sequential upgrade rule (no version skipping) and the supported upgrade paths tables. Load in Workflow 03.
references/request-patterns-reference.md - Which workflows run for each request shape (full upgrade, multi-hop, analysis only, reports only). Read at the start of a session.
references/next-hop-readiness-reference.md - Read-only answer to "what do I need for the next Rails version?". Load for the Next-Hop Readiness request shape.
references/no-test-suite-smoke-reference.md - Load from Workflow 01 when no runnable RSpec/Minitest suite exists - Rails boot, routes, migration-status, and build smoke baseline with partial-confidence reporting
references/deprecation-warnings-reference.md - Finding and fixing deprecations
references/staying-current-reference.md - Keeping up with Rails releases
references/breaking-changes-by-version-reference.md - Quick lookup
references/multi-hop-strategy-reference.md - Multi-version planning
references/testing-checklist-reference.md - Comprehensive testing
references/gem-compatibility-reference.md - Gem update order and the "no compatible version" playbook (fork / vendor / replace). Load only when Workflow 06's compatibility check produced blockers.
references/js-compressor-sprockets-mismatch-reference.md - Keeping terser working when the target Rails pins Sprockets to the 2.x line. Load only when JS_COMPRESSOR_GEM_MISMATCH fires.

Detection Pattern Resources

detection-scripts/patterns/rails-*.yml - Version-specific patterns for direct detection
detection-scripts/scan_patterns.rb - Runs every pattern for a hop against the app and prints a findings table. Run it in Workflow 05 instead of one Grep per pattern.
detection-scripts/gem_limits.rb - Lists the locked gems whose gemspec excludes the target Rails, from the lockfile alone. First pass of Workflow 06.

Report Templates

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

Workflow index

When user requests an upgrade, follow this workflow. Sequential Process is Critical: run in order, read each file when you reach it. Gates block.

#	Name	Purpose	File
00	Verify latest patch	MANDATORY PRE-STEP. App on the latest patch of its current series before any minor/major hop	`workflows/00-verify-latest-patch-workflow.md`
01	Run test suite	MANDATORY FIRST STEP. How to run and verify test suite; blocks on any failure	`workflows/01-run-test-suite-workflow.md`
02	Resolve deprecation warnings	Make warnings visible, collect what the current version emits, fix them on the current version	`workflows/02-resolve-deprecation-warnings-workflow.md`
03	Validate upgrade path	Single-hop or multi-hop, individual hops planned	`workflows/03-validate-upgrade-path-workflow.md`
04	Set up next_rails	EARLY SETUP. Delegated to the skill listed under External Dependencies	`workflows/04-setup-next-rails-workflow.md`
05	Detect breaking changes	How to run breaking change detection directly	`workflows/05-detect-breaking-changes-workflow.md`
06	Check gem compatibility	Per-lockfile gem compatibility check against the target Rails version	`workflows/06-check-gem-compatibility-workflow.md`
07	Boot smoke test	Boot under `Gemfile.next` and run the models suite there, to catch what the resolver and the grep can't see	`workflows/07-boot-smoke-test-workflow.md`
08	Generate upgrade report	How to generate upgrade reports	`workflows/08-generate-upgrade-report-workflow.md`
09	Generate app:update preview	How to generate app:update previews	`workflows/09-generate-app-update-preview-workflow.md`
10	Implement and upgrade	Present reports, apply fix-before-bump changes, bump the Gemfile, run tests against both versions	`workflows/10-implement-and-upgrade-workflow.md`
11	Sync CI config	MANDATORY before opening the upgrade PR. How to verify CI config matches the upgraded Gemfile	`workflows/11-sync-ci-workflow.md`
12	Align load_defaults	AFTER THE UPGRADE IS COMPLETE. Delegates to the rails-load-defaults skill	`workflows/12-align-load-defaults-workflow.md`
13	Mention cleanup	USER-TRIGGERED. Delegates to the `upgrade-cleanup` plugin only when the user explicitly asks	`workflows/13-mention-cleanup-workflow.md`

The Purpose column is a summary. Gates live only in each workflow's ## Gates section. Which workflows run depends on the request shape (full upgrade, multi-hop, analysis only, reports only): references/request-patterns-reference.md.

Key Principles

Run Detection Directly (run detection-scripts/scan_patterns.rb, then Read the affected files; never generate a detection script for the user to run)
Load Workflows as Needed (don't hold everything in memory)
Follow FastRuby.io Methodology (incremental upgrades, assessment first)

Everything else that used to be listed here lives in the workflow it governs: see each workflow's Purpose and Gates.

Bundled files

The model reads these on demand while the skill is loaded. They are exposed as readable files and are never executed.

and 8 more files.

Frequently asked questions

What does the Rails Upgrade AI skill do?

Why use Rails Upgrade on TypingMind?

Because you install it once and use it with any model. Rails Upgrade is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Rails Upgrade in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/ombulabs/claude-code_rails-upgrade-skill/tree/main/rails-upgrade. TypingMind reads its SKILL.md and bundles its files and installs it as a skill you can enable per chat.

Which AI models can use Rails Upgrade?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Rails Upgrade?

As many as you like. As long as a model supports skills, you can use Rails Upgrade with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Rails Upgrade AI skill free?

Yes. It is published on GitHub by ombulabs under the MIT license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

Rails Upgrade Assistant Skill

Skill Identity

Terminology

Dependencies

Core Methodology (FastRuby.io Approach)

CRITICAL: Dual-Boot Code Pattern with NextRails.next?

Available Resources

Core Documentation

Version-Specific Guides (Load as needed)

Examples (Load when user needs clarification)

External Dependencies

Reference Materials

Detection Pattern Resources

Report Templates

Workflow index

Key Principles

Bundled files

Frequently asked questions

Related AI Skills

Set up your own AI workspace now

CRITICAL: Dual-Boot Code Pattern with `NextRails.next?`