PENGO Workbench
Workbench / Patterns / Undeclared Side Effect

PAT-0420

Undeclared Side Effect

A structural condition where an operation modifies regions outside its declared target scope without a declared propagation or side-effect rule.

Primary Lenses

LEN-0240

Overreach Lens

Detects structure that exceeds declared scope or authority reach.

Lens Application

The Overreach Lens is a primary inspection mechanism for Undeclared Side Effects because it directs attention to mismatches between declared operational scope and observed effects. It helps surface cases where changes propagate beyond authorized regions without an explicit side-effect or propagation rule.

Inspect For

  • Modifications outside the declared target scope
  • Effects on adjacent, inherited, or shared regions
  • Missing propagation or side-effect declarations
  • Authority boundaries exceeded during execution

Avoid

Treat scope excess as an inspection signal requiring follow-up rather than proof that an Undeclared Side Effect has occurred.

LEN-0250

Propagation Lens

Traces how structural declarations, effects, or state changes propagate across boundaries or stages.

Lens Application

The Propagation Lens is a primary inspection mechanism for Undeclared Side Effects because it follows how effects, state changes, or structural updates cross declared boundaries. It helps surface mismatches between stated scope and observed propagation behavior without treating the mismatch as conclusive by itself.

Inspect For

  • Effects appearing outside the declared target scope
  • Missing propagation or side-effect declarations
  • Boundary crossings during operation execution
  • State changes in adjacent or downstream regions

Avoid

Treat unexpected propagated changes as inspection signals, not as confirmation that Undeclared Side Effects have occurred without checking whether a declaration, rule, or contextual allowance exists.

Secondary Lenses

LEN-0220

Isolation Boundary Lens

Evaluates whether structural constraints, effects, and regions remain contained within declared boundaries.

Lens Application

As a secondary lens, the Isolation Boundary Lens can support inspection of Undeclared Side Effects by focusing attention on containment assumptions around target scopes, affected regions, and declared effect boundaries. It may surface side-effect signals when observed modifications appear outside the operation’s stated isolation limits.

Inspect For

  • Changes in regions outside the declared target scope
  • Missing propagation or side-effect declarations
  • Boundary crossings not reflected in operation metadata
  • Shared state, caches, or linked regions affected indirectly

Avoid

Treat containment failures as inspection signals requiring further analysis, not as proof that an Undeclared Side Effect has occurred.

Primary Issue Matches

Supporting Issue Matches