Event Reliability

Executive Summary

Event Reliability defines reliability expectations for Algosure event publishing and consumption. It covers outbox alignment, idempotent consumers, retry rules, dead-letter handling, failure visibility, and event replay as a future capability.

Why This Exists

Event-driven architecture fails when events are lost, duplicated, silently ignored, or replayed unsafely. Algosure requires predictable event behavior across Domains, AIOS, notifications, analytics, integrations, and audit.

Owner

The owner is the Chief Product Officer and Enterprise Architect.

Business Value

Reliable events support trustworthy workflows, recoverable failures, operational insight, and future scaling.

Reliability Model

flowchart LR
    Publisher[Publisher]
    Outbox[Outbox]
    Delivery[Event Delivery]
    Consumer[Consumer]
    Retry[Retry]
    DeadLetter[Dead-Letter Handling]
    Audit[Audit Trail]

    Publisher --> Outbox
    Outbox --> Delivery
    Delivery --> Consumer
    Consumer -->|temporary failure| Retry
    Retry --> Consumer
    Consumer -->|terminal failure| DeadLetter
    Delivery --> Audit
    DeadLetter --> Audit

Reliability Rules

Rule	Requirement
Use outbox for important events	Events that coordinate processes, audit, integrations, analytics, notifications, or AIOS should be captured reliably.
Consumers are idempotent	Duplicate event delivery must be safe.
Retries are bounded and visible	Retry attempts must be observable and should not run forever without escalation.
Dead-letter handling is required	Events that cannot be processed after retry policy must be parked for review.
Failures are auditable	Publication and consumption failures must be traceable.
Replay is future capability	Event replay should be supported by preserving event identity, version, metadata, and ordering assumptions.

Retry Rules

Failure Type	Architecture Response
Temporary dependency failure	Retry with bounded policy and operational visibility.
Consumer validation failure	Do not retry blindly; park or reject according to error classification.
Unsupported event version	Park for compatibility review or route to version-specific handler.
Tenant authorization failure	Stop processing and create audit evidence.
Duplicate event	Ignore or merge idempotently.
Poison event	Move to dead-letter handling with reason and owner.

Dead-Letter Handling

Dead-letter handling is a governed operational state for events that cannot be processed safely.

Requirement	Meaning
Preserve original event	Keep event ID, metadata, payload reference, and failure reason.
Assign owner	Source or consuming module ownership must be clear.
Support review	Operations and architecture must be able to inspect failure cause.
Support replay or discard decision	Dead-letter events require explicit resolution.
Protect tenant data	Review access must follow tenant and security controls.

Non-Implementation Boundary

This document does not define retry intervals, dead-letter queue products, broker configuration, outbox schema, scheduler implementation, or replay tooling.