[rstammer]

Why

0.1.0 declared rack >= 2.2 and did not work on Rack 2.

Rack 3 requires response header keys to be lowercase. Rack 2 left the case alone, and its file server returns Content-Type. The endpoint reads that header to decide whether to inject the <base> tag — so on Rack 2 the injection never fired, and a mounted game served its index.html and then none of its assets. Silent: correct status, correct headers, blank canvas.

Bounding the version rather than adding a case-insensitive lookup. On Rack 3 the lowercase key is a guarantee, so the failure mode stops existing instead of being defended against forever.

The floor is 3.0.3, not 3.0

Found by actually running it. Rack::URLMap up to 3.0.2 calls Regexp.new with the third argument Ruby 3.2 removed, and URLMap backs both Rack::Builder#map and Rails' mount — so on the Ruby this gem now requires, anything below 3.0.3 raises ArgumentError the moment you mount it, which is the only way the gem is ever used.

Changes

• rack >= 3.0.3, < 4; required_ruby_version >= 3.2 (it said 3.1, but the dev dependencies have needed 3.2 since they were written)
• CI: suite on Ruby 3.2/3.3/3.4, plus one run pinned to the oldest supported Rack so the lower bound is a tested claim. Separate jobs lint and build-install-require the packaged gem — a gemspec whose files list has a hole still packages fine and only fails for whoever installs it.
• Standard as the linter, applied across the codebase. rake runs spec + standardrb.
• 0.2.0, CHANGELOG and README updated.

A note on the linter commits

This branch adopts rubocop-rails-omakase in one commit and replaces it with Standard in a later one. That is the actual sequence of the work rather than a tidied-up version of it, kept because the two configs are worth contrasting: omakase enables 45 cops and is designed to be overridden, Standard enables 353 and is designed not to be. The visible difference is bracket spacing ([ "lib" ] vs ["lib"]), which is why the switch touches every file containing a literal.

Two rewrites in that commit are not whitespace: Dir.children(dir).empty? became Dir.empty?(dir), and a bare rescue StandardError lost the redundant class. Both mean what they meant before.

Verified

CI green on all six jobs. The first run was not, and one commit is the workflow being fixed against itself:

• an unset matrix axis arrives as RACK_VERSION="", and an empty string is truthy in Ruby, so every unpinned job asked for gem "rack", ""
• gem install --local forbids the network, so the install-into-an-empty-dir step could not fetch the dependency it exists to check
• an include entry matching an existing combination is merged into it, so the pinned-rack entry swallowed the plain Ruby 3.2 job rather than joining it

Locally: bundle exec rake green on Ruby 3.4.7, suite green on 3.3.5, across all three rack resolutions (latest 3.2.6, empty env, pinned 3.0.3).

Note

This is a breaking change for anyone on Rack 2, and 0.1.0 is published. In practice nobody could have been running it there, since the feature that breaks is the one the gem exists for.