---
title: "3DARCH-FT-2 — Shared contracts and reusable interface foundations"
description: "Enable application teams to evolve real-time interactions and user interfaces against shared types, constants, TypeScript rules, lint rules, and reusable UI components rather than duplicating incompatible definitions."
---

# Shared contracts and reusable interface foundations

| Feature | Parent Epic | Delivery status | Status source | Owner | Approved for Solution |
|---|---|---|---|---|---|
| `3DARCH-FT-2` | [3DARCH-EP-1 — Engineering Platform, Quality, and Operability](../../3darch-ep-1.md) | `IN_BACKLOG` | `EXACT` | 3D Architecture Wizzard team | No |

## Description

Enable application teams to evolve real-time interactions and user interfaces against shared types, constants, TypeScript rules, lint rules, and reusable UI components rather than duplicating incompatible definitions.

## User or operator problem

Application teams risk incompatible real-time behavior and inconsistent interfaces when contracts, constants, and components are duplicated.

## Expected value

Keeps client, service, and interface behavior aligned while reducing duplicated definitions.

## Scope

Includes shared player, chat, voice, seat, authentication, control, socket, TypeScript, lint, and reusable UI foundations.

### Exclusions

- End-user product behavior and solution or release authorization are outside these engineering Features.

## Acceptance outcomes

- [ ] Frontend and backend consume the same player, chat, voice, seat, and authentication contracts.
- [ ] Common controls and socket event names have one shared definition.
- [ ] Reusable UI components can be developed, demonstrated, and tested independently.

## Dependencies

- [3DARCH-FT-1 — Reproducible monorepo development workspace](./3darch-ft-1.md)

## Risks

- Shared contract changes can break multiple applications unless all consumers are validated together.

## Human approval

Linas approved this Feature for documentation on 2026-09-02T10:40:43.220Z. It is **not Approved for Solution** and has no implementation approval.

- [Documentation decision](https://discord.com/channels/1518726359512387766/1543925247361814568/1544658325738885201)

## Delivery status evidence

The Feature was separately registered at `IN_BACKLOG` as an accepted catalogue boundary. This records backlog retention, not design or delivery progress.

- Event: Catalogue registration
- Actor and authority: Linas — Human project team member
- Reason: The Feature catalogue was accepted for governed documentation and retained in the backlog.
- [Status evidence](https://discord.com/channels/1518726359512387766/1543925247361814568/1544658325738885201)

## Architecture traceability

- Requirements: none derived.
- Readiness: Not started.

Architecture solution work must not begin until a separate human **Approved for Solution** decision is recorded.

## Tasks

[Review the Tasks group](./3darch-ft-2/tasks.md). No canonical implementation Tasks have been defined.

## Original source

- [Discord – Scope – Linas: original Feature request](https://discord.com/channels/1518726359512387766/1543925247361814568/1544647879111483562)
- [Discord – Scope – Linas: proceed with documented mapping](https://discord.com/channels/1518726359512387766/1543925247361814568/1544658325738885201)

### Legacy implementation evidence

The Feature boundary was mined from legacy revision `c0ced47ecaf4426f47e5c2e4868677f7144b951a`.

- [`packages/utils/types/src/`](https://gitea.lego-cloud.eu/corp-v1-3darch-legacy/corp-v1-3darch-legacy/src/commit/c0ced47ecaf4426f47e5c2e4868677f7144b951a/packages/utils/types/src/)
- [`packages/utils/constants/src/`](https://gitea.lego-cloud.eu/corp-v1-3darch-legacy/corp-v1-3darch-legacy/src/commit/c0ced47ecaf4426f47e5c2e4868677f7144b951a/packages/utils/constants/src/)
- [`packages/utils/typescript-config/`](https://gitea.lego-cloud.eu/corp-v1-3darch-legacy/corp-v1-3darch-legacy/src/commit/c0ced47ecaf4426f47e5c2e4868677f7144b951a/packages/utils/typescript-config/)
- [`packages/utils/eslint-config/`](https://gitea.lego-cloud.eu/corp-v1-3darch-legacy/corp-v1-3darch-legacy/src/commit/c0ced47ecaf4426f47e5c2e4868677f7144b951a/packages/utils/eslint-config/)
- [`packages/stardust/`](https://gitea.lego-cloud.eu/corp-v1-3darch-legacy/corp-v1-3darch-legacy/src/commit/c0ced47ecaf4426f47e5c2e4868677f7144b951a/packages/stardust/)