Runtime bundled-library drift
Ruby 4.0 bundled gems removed default gems Ruby 4.0
Incremental deploys pass but a cache purge reproducibly breaks boot.
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: Buildpack cache conceals missing explicit gem
Likely root cause: Incremental deploys pass but a cache purge reproducibly breaks boot.
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
Incremental deploys pass but a cache purge reproducibly breaks boot.
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 bundled gems removed default gems Ruby 4.0
site:ruby-lang.org Ruby 4.0 default gems bundled gems