# 0001: Pin Unreal Engine 5.5 LTS

Status: Accepted

Date: 2026-05-25

## Context

V5 is scoped as a full open-world UE project with large binary content,
networked runtime systems, and platform-specific cooks. The project needs a
stable launch engine so gameplay code, platform certification, middleware, and
binary content stay aligned.

## Decision

V5 pins the launch branch to Unreal Engine 5.5 LTS. `V5/ue/V5.uproject` uses
`EngineAssociation` `5.5`; engine upgrades during launch development require a
new decision record and migration plan.

## Consequences

- Tooling and commandlets target UE5.5 paths.
- Plugin certification is assessed against UE5.5.
- Platform cooks use UE5.5 as their compatibility baseline.