Installer generates shakapacker.yml with compile: true in development causing 'Slow setup' warnings

[justin808]

Problem

The React on Rails installer is generating config/shakapacker.yml with incorrect compile settings, causing unnecessary "Slow setup for development" warnings when using Procfiles with bin/dev.

Current Behavior

The generated shakapacker.yml has:

development:
  <<: *default
  compile: true  # ❌ Wrong - causes on-demand compilation

This causes Rails to attempt on-demand asset compilation even when bin/shakapacker-dev-server or bin/shakapacker --watch are running via Procfiles, resulting in this warning on every request:

Shakapacker::Compiler - Slow setup for development

Prepare JS assets with either:
1. Running bin/shakapacker-dev-server
2. Set compile to false in shakapacker.yml and run bin/shakapacker -w

Expected Behavior

The correct configuration should be:

default: &default
  # ... other settings ...
  compile: false  # Default is false (use Procfiles)

development:
  <<: *default
  # Inherits compile: false - no on-demand compilation

test:
  <<: *default
  compile: true  # Only tests need on-demand compilation

production:
  <<: *default
  compile: false  # Assets are precompiled

Impact

• Developers see unnecessary warnings on every page load
• Confusion about whether the dev server is working correctly
• Potential performance impact from Rails attempting compilation checks

Environment

• React on Rails: 16.1.1
• Shakapacker: 9.x (from GitHub main)
• Rails: 8.0.3

Suggested Fix

Update the installer template for shakapacker.yml to:

1. Set compile: false in the default section
2. Remove compile: true from development section (let it inherit)
3. Keep compile: true only in test section

Related Files

This appears to affect the installer generator template, likely in:

• lib/generators/react_on_rails/install/templates/base/config/shakapacker.yml

Reproduction

1. Run react_on_rails installer to create a new demo
2. Run bin/dev (which starts rails server + shakapacker-dev-server)
3. Visit any page
4. Observe "Slow setup for development" warning in logs

References

Found while working on: shakacode/react_on_rails-demos#20