# Causality

> A design rule that every effect records the event that caused it, so its order can be reasoned about.

Record: `architecture:causality`
Kind: principle
Layer: [Causality Core](https://banes-lab.com/records/layer/causality-core.md)
Severity: contextual
Scope: event, workflow, distributed state
Canonical: https://banes-lab.com/ontology#architecture-causality

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Runtime Extensibility](https://banes-lab.com/records/architecture/runtime-extensibility.md) and before [Causal Consistency](https://banes-lab.com/records/architecture/causal-consistency.md).

## Repair

- Refactored by: Add Causation ID, Add Ordering Rules
- Detected by: missing causation/correlation metadata
- Violated by: processing effects without known cause/order
- Measured by: causal trace completeness
- Enforced by: event schema and workflow tests

## Requires

- [Causation Tracking](https://banes-lab.com/records/lexicon/causation-tracking.md)

## Reinforces

- [Traceability](https://banes-lab.com/records/architecture/traceability.md)
- [Event Ordering](https://banes-lab.com/records/architecture/event-ordering.md)

## Enables

- [Correct Workflow Reasoning](https://banes-lab.com/records/lexicon/correct-workflow-reasoning.md)

## Conflicts with

- [Unordered Side Effects](https://banes-lab.com/records/lexicon/unordered-side-effects.md)

## In tension with

- [Parallelism](https://banes-lab.com/records/architecture/parallelism.md)

## Tensions

- [Causality / Parallelism](https://banes-lab.com/records/tension/causality-parallelism.md)

## Contracts

- [Causality Core](https://banes-lab.com/records/algorithms/causality-core.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Causality / Ordering / Distributed Time](https://banes-lab.com/records/architecture-category/causality-ordering-distributed-time.md)

## Reinforced by

- [Causal Dependency](https://banes-lab.com/records/architecture/causal-dependency.md)
- [Causation ID](https://banes-lab.com/records/architecture/causation-id.md)
- [Distributed Tracing](https://banes-lab.com/records/architecture/distributed-tracing.md)

## Linked from

- [Execution joins the halves](https://banes-lab.com/software-architecture/principles/execution-joins-the-halves.md)
- [Causality / Ordering / Distributed Time](https://banes-lab.com/ontology/principles/architecture-category-causality-ordering-distributed-time.md)
- [Observability / Auditability / Traceability](https://banes-lab.com/ontology/principles/architecture-category-observability-auditability-traceability.md)
- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Causality / Ordering / Distributed Time](https://banes-lab.com/ontology/lexicon/lexicon-category-causality-ordering-distributed-time.md)
- [Architectural Clusters](https://banes-lab.com/ontology/algorithms/algorithms-domain-architectural-clusters.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)