Generator still shows overall success banner after failed Shakapacker install with --ignore-warnings

[ihabadham]

Environment

• Ruby version: 3.3.7
• Rails version: 8.1.2
• Shakapacker version: 9.4.0
• React on Rails version: 16.x (master reproduced at 14afa475db74a381f2148b42f999e4fa7507b97b on March 14, 2026)

Expected behavior

When shakapacker:install fails and --ignore-warnings is set, the generator should not end with the overall 🎉 React on Rails Successfully Installed! banner or quick-start instructions that imply the app is ready to use.

At minimum, the final message should clearly indicate a partial/incomplete installation and avoid suggesting commands like ./bin/dev unless the required Shakapacker files were actually created.

Actual behavior

This specific false-success message from #2422 is fixed on current master — after shakapacker:install fails, the generator no longer prints ✅ Shakapacker installed successfully!.

However, the generator still ends with the overall success banner even though Shakapacker installation failed:

ERROR: 🚫 Failed to install Shakapacker automatically.
...
╔════════════════════════════════════════════════════════════════════════╗
║  🎉 React on Rails Successfully Installed!                             ║
╚════════════════════════════════════════════════════════════════════════╝
...
📦 Shakapacker setup may be incomplete

In the reproduced app, the install is visibly incomplete:

• package.json is missing
• bin/shakapacker is missing
• bin/shakapacker-dev-server is missing

But the final message still says to run ./bin/dev and visit /hello_world.

In practice, ./bin/dev static then fails immediately with:

unknown command: bin/shakapacker --watch

Related issue

• Generator falsely reports success after failed Shakapacker install with --ignore-warnings #2422 fixed the intermediate false success message (✅ Shakapacker installed successfully!) via fix: replace marker file with Thor-idiomatic force option (#2289) #2411.
• This follow-up is about the remaining final success banner / quick-start UX after a known failed Shakapacker install.

Suspected root cause

run_generators still calls add_post_install_message unconditionally once execution continues under --ignore-warnings, even if GeneratorMessages already contains a fatal Shakapacker install error.

Suggested fix

Suppress or replace the final helpful_message_after_installation success banner when Shakapacker installation failed.

Possible approaches:

• Track a failure flag when install_shakapacker fails
• Render a different final message such as "React on Rails installation incomplete"
• Avoid advertising ./bin/dev / visit URL instructions unless the expected Shakapacker files actually exist

Reproduction script

#!/bin/bash
set -euo pipefail

APP_DIR="/tmp/test_edge_case_$$"
HELPER_DIR="/tmp/test_edge_case_tools_$$"
mkdir -p "$HELPER_DIR"

# Preserve Ruby/Bundler tooling even if your Ruby install lives in a path that
# gets filtered out below (for example via mise).
for exe in ruby bundle bundler gem rake rails; do
  target=$(command -v "$exe" || true)
  if [ -n "$target" ]; then
    ln -sf "$target" "$HELPER_DIR/$exe"
  fi
done

rails new "$APP_DIR" --minimal --skip-git --skip-bundle --skip-test --skip-javascript 2>/dev/null
cd "$APP_DIR"

cat >> Gemfile << GEMEOF
gem "shakapacker", "9.4.0"
gem "react_on_rails"
gem "foreman"
GEMEOF

bundle install --quiet

# Strip node from PATH so shakapacker:install fails, while keeping Ruby/Bundler available.
CLEAN_PATH=$(echo "$PATH" | tr ':' '\n' | grep -v -E '(node|nvm|fnm|volta|mise)' | tr '\n' ':')
PATH="$HELPER_DIR:$CLEAN_PATH" bundle exec rails generate react_on_rails:install --ignore-warnings 2>&1 | tee repro.log

# Look for:
# - "Failed to install Shakapacker automatically."
# - later, the final "React on Rails Successfully Installed!" banner
#
# Then verify the install is incomplete:
# - package.json missing
# - bin/shakapacker missing
# - bin/shakapacker-dev-server missing
# - ./bin/dev static fails with: "unknown command: bin/shakapacker --watch"

Impact

Low-to-medium — this requires both:

1. --ignore-warnings
2. a failed Shakapacker install

But when it happens, the final UX is still misleading because the app looks "installed" even though the normal dev workflow is broken.