ruby-templates

Checks and a safe formatter for Rails views in ERB, Haml and Slim, for CI, pre-commit hooks and editors. It is the command line of the Ruby Templates VS Code extension, so the editor and CI report the same errors and format the same way.

• No Ruby needed. A single prebuilt binary (written in Rust): no gems, no Bundler, fast on large app/views.
• Errors the real engines would raise: Ruby syntax inside ERB, Haml and Slim (checked with Prism), unclosed <% and blocks, mismatched HTML tags, missing alt, Haml and Slim indentation and nesting errors, unresolved render partials and strict locals mismatches, with Erubi's, Rails', Haml's and Slim's own messages.
• Formatting that changes only whitespace: indentation, trailing whitespace, blank lines, the final newline. It never rewraps lines or touches Ruby, checks that the template still compiles the same, and leaves a file unchanged (saying why on stderr) when in doubt.

npm install --save-dev @x-ror/ruby-templates

npx ruby-templates check app/views            # errors and warnings; exit 1 if any
npx ruby-templates format --check app/views   # list files that would change; exit 1 if any
npx ruby-templates format --write app/views   # format them in place
npx ruby-templates format --stdin-filepath app/views/users/show.html.erb < show.html.erb

Exit codes: 0 ok, 1 diagnostics or files that would change, 2 usage or I/O error.

The only formatter setting is the indentation width, from .editorconfig (indent_size, default 2), plus --align-comments for ERB comments; see Formatting in the extension's README.

The binary comes from a per-platform package (Linux x64/arm64, macOS arm64/x64, Windows x64) installed as an optional dependency; RUBY_TEMPLATES_BINARY points the wrapper at another build.