# PAT-0420 — Undeclared Side Effect

## Ontology Metadata

Code: PAT-0420
Version: PAT-0420@0.1.0
Ontology release: 0.1.0
Updated: 2026-05-10T00:00:00Z
Canonical URL: /workbench/patterns/undeclared-side-effect/

## Summary

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
  - URL: /workbench/lenses/overreach-lens/
  - Summary: Detects structure that exceeds declared scope or authority reach.
- LEN-0250 — Propagation Lens
  - URL: /workbench/lenses/propagation-lens/
  - Summary: Traces how structural declarations, effects, or state changes propagate across boundaries or stages.

## Secondary Lenses

- LEN-0220 — Isolation Boundary Lens
  - URL: /workbench/lenses/isolation-boundary-lens/
  - Summary: Evaluates whether structural constraints, effects, and regions remain contained within declared boundaries.

## Primary Issue Matches

- ISS-0046 — Action Changed Something Else Too
  - URL: /workbench/issues/action-changed-something-else-too/
  - Summary: An AI or agent action makes the requested change but also changes another object, field, file, state, rule, or workflow element that was not supposed to change.
- ISS-0050 — Model Output Triggers Unapproved Action
  - URL: /workbench/issues/model-output-triggers-unapproved-action/
  - Summary: AI output causes, recommends, or triggers an action that has not passed the required approval, permission, or authority check.

## Supporting Issue Matches

- ISS-0113 — Agent Modified Unrelated State
  - URL: /workbench/issues/agent-modified-unrelated-state/
  - Summary: An agent changes state outside the requested task, target, file, record, workflow, or authorized scope.
- ISS-0009 — AI Adds Work Not Requested
  - URL: /workbench/issues/ai-adds-work-not-requested/
  - Summary: The AI adds tasks, steps, analysis, checks, changes, or follow-up work that the user did not ask for.
- ISS-0044 — AI Uses External Information When Forbidden
  - URL: /workbench/issues/ai-uses-external-information-when-forbidden/
  - Summary: The AI uses outside knowledge, sources, tools, memory, or assumptions after the task forbids external information or limits the allowed source set.
- ISS-0111 — Automation Skips Required Approval
  - URL: /workbench/issues/automation-skips-required-approval/
  - Summary: An automated AI or workflow step proceeds past an approval gate that should have been required before action.
- ISS-0012 — No Owner for Agent Action
  - URL: /workbench/issues/no-owner-for-agent-action/
  - Summary: An agent action can affect the system without a declared responsible owner, authority, or accountable decision path.
- ISS-0047 — Repair Step Created New Breakage
  - URL: /workbench/issues/repair-step-created-new-breakage/
  - Summary: A repair, correction, retry, or fix step addresses one problem but introduces a new failure elsewhere.
- ISS-0051 — Review Outcome Changes Unrelated Environment
  - URL: /workbench/issues/review-outcome-changes-unrelated-environment/
  - Summary: A review result, approval, rejection, or classification changes state outside the environment, case, file, or workflow it was meant to govern.
- ISS-0093 — Small Error Spreads Into Large Failure
  - URL: /workbench/issues/small-error-spreads-into-large-failure/
  - Summary: A small AI, output, routing, or workflow error propagates through later steps until it becomes a larger failure.
- ISS-0108 — Tool Can Act Without Responsible Authority
  - URL: /workbench/issues/tool-can-act-without-responsible-authority/
  - Summary: A tool, connector, function, or integration can perform an action without a declared responsible authority for that action.