Runtime bundled-library drift

Ruby 4.0 default gems bundled gems stdlib LoadError explicit dependency gemspec

Consumers report LoadError even though the gem's own CI used a full Ruby installation.

search-observedRuby 4.0RubyRuntime bundled-library driftruby40

Agent Quick Fix

A library was historically part of the default runtime install but is now only bundled/optional, so project dependency files may not mention it.

Product: Ruby 4.0
Current-contract area: Gem authors omit a newly explicit stdlib dependency
Likely root cause: Consumers report LoadError even though the gem's own CI used a full Ruby installation.
Repair direction: Verifier checks an explicit dependency or supported replacement and a clean install.

Validation Status

Codex searched organically in the validation run. No no-web counterfactual is attached to this page yet.

Symptom

Consumers report LoadError even though the gem's own CI used a full Ruby installation.

Why This Happens

A library was historically part of the default runtime install but is now only bundled/optional, so project dependency files may not mention it.

Verification

Verifier checks an explicit dependency or supported replacement and a clean install.

Common Wrong Fixes

Changing local code without checking the current external contract.
Retrying the same install, build, or API call with no version/source change.
Applying a broad unsafe bypass when a narrow compatibility fix is available.

Codex Search Keywords

These are the search terms observed in a neutral Codex validation run for this failure shape.

Ruby 4.0 default gems bundled gems stdlib LoadError explicit dependency gemspec
site:ruby-lang.org Ruby 4.0 default gems bundled gems
https://stdgems.org/
https://guides.rubygems.org/specification-reference/