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Worker Safety

WS004 · Mutable singleton

Default severity: MEDIUM · Framework: Any

What it checks

Section titled “What it checks”

A singleton is created once and then reused. Under a persistent worker “once” means once per worker process, so every request shares the same instance and everything written into it.

What to review

Section titled “What to review”
  • Register the class in your container instead, so its lifetime is controlled by the framework.
  • Keep the shared instance immutable: readonly properties set in the constructor only.
  • If it must hold per-request values, resolve a fresh instance per request (Laravel: scoped()).

Inspect this rule

Section titled “Inspect this rule”
Terminal window
vendor/bin/worker-safety rules WS004

Accepting a reviewed risk

Section titled “Accepting a reviewed risk”

Use a targeted suppression or a baseline only after reviewing the value’s origin and lifetime. Changing an assignment elsewhere may not invalidate an existing property-level suppression.