API Versioning¶

Executive Summary¶

API Versioning defines how Algosure API contracts should evolve. Versioning must protect mobile, web, AIOS, and integration consumers while allowing Domains to change responsibly.

Why This Exists¶

APIs are long-lived contracts. Unmanaged changes can break clients, AIOS tool calls, integrations, analytics ingestion, and customer workflows.

Owner¶

The owner is the Chief Product Officer and Enterprise Architect.

Business Value¶

Versioning reduces client breakage, supports planned migration, and makes API lifecycle governance explicit.

Versioning Model¶

flowchart LR
    V1[API v1]
    Compatible[Backward-Compatible Change]
    V1b[API v1 Updated]
    Breaking[Breaking Change]
    V2[API v2]
    Consumers[Mobile, Web, AIOS, Integrations]

    V1 --> Compatible
    Compatible --> V1b
    V1 --> Breaking
    Breaking --> V2
    V1b --> Consumers
    V2 --> Consumers

Versioning Rules¶

Rule	Requirement
Version public contracts	Public application and integration APIs require explicit versioning.
Prefer backward compatibility	Additive, optional changes are preferred over breaking changes.
Breaking changes require new version	Removing fields, changing meaning, changing authorization assumptions, or changing command semantics requires a new version.
Domain owns version impact	The owning Domain must assess consumer impact before changing its API.
OpenAPI as future source	OpenAPI should become the versioned contract source when endpoint specs are approved.
Deprecation is explicit	Deprecated versions require migration guidance, retirement policy, and consumer visibility.

Compatibility Guidance¶

Change	Compatibility
Add optional response field	Usually compatible.
Add optional filter	Usually compatible.
Add stricter authorization check	Potentially breaking; requires security and consumer review.
Remove response field	Breaking.
Rename resource	Breaking.
Change command behavior	Breaking.
Change error shape	Breaking.
Change pagination semantics	Potentially breaking.

Non-Implementation Boundary¶

This document does not define URL version placement, header versioning, OpenAPI folder layout, release cadence, or sunset automation.