Shared Mutable State

Kind: anti-pattern

Layer: Enforcement Core

Record: architecture:shared-mutable-state

Severity: discouraged

Scope: modularity, state_transaction

Formed by: Expose writable state across modules, allow multiple actors to mutate it, omit ownership and synchronization, and let behavior depend on mutation order.

Canonical: Ontology

A defect in which writable state is shared across modules with no owner and no synchronization.

Listed in Architecture principles, after Hardcoded Configuration and before Boundary Leakage.

Refactored by

• Encapsulate State
• Assign Owner
• Make Immutable
• Introduce Transaction Boundary
• Apply Concurrency Control

Severity

• discouraged

Category

• Anti-patterns

Force

• Modularity
• State transaction

Detected by

• rules/eslint/closure-no-module-singleton.eslint.rule.ts

Negated by

• Immutability
• State Isolation

Violates

• Immutability
• Encapsulation
• Modularity

Linked from

• Shared surfaces
• Coordination is software
• Principles are typed
• Seven controls, seven classes
• A concern is a component
• Anti-patterns
• Correctness / Determinism / Verification
• Core Modular Design
• Transactions / State / Concurrency
• Architecture Review Evolution Governance
• Core Modular Design
• Transactions / State / Concurrency
• Severity levels
• The forces