# Architecture Decision Records

This directory contains Architecture Decision Records (ADRs) used throughout the OTA Reference Design.

Unlike ADRs maintained within a single commercial project, these documents are **not** a historical record of decisions made for one specific product.

Instead, they serve as **reference architectural decisions** illustrating how an experienced engineer might reason about common OTA design problems under different technical constraints.

## Purpose

Each ADR documents:

- the engineering context;
- the decision being considered;
- the factors driving that decision;
- the expected consequences;
- the situations where the decision is appropriate;
- the situations where another approach may be preferable.

The goal is not to declare one solution universally correct.

The goal is to explain **why** a particular decision would be reasonable for a particular class of systems.

## Relationship to the Documentation

The repository intentionally separates three different types of documents.

### Concept Articles (`docs/`)

Concept articles explain the design space.

They answer questions such as:

- What approaches exist?
- How do they work?
- What problems do they solve?
- What trade-offs do they introduce?

Their purpose is education.

### Architecture Decision Records (`adr/`)

ADRs answer a different question:

> Given a particular set of engineering constraints, what decision would be made, and why?

They intentionally focus on architectural reasoning rather than implementation details.

### Decision Matrix

After the individual ADRs, the series concludes with a decision matrix that compares the approaches and helps relate system constraints to architectural choices.

The matrix is not intended to automatically select a solution. Instead, it provides a structured way to evaluate trade-offs.

## Educational Nature

These ADRs are examples.

A real product may reach different conclusions depending on its:

- reliability requirements;
- hardware architecture;
- network constraints;
- operational model;
- regulatory requirements;
- maintenance strategy;
- business priorities.

For that reason, every ADR should be read as:

> "Given these assumptions, this is the architectural decision we would make."

rather than:

> "This is the only correct solution."

## Design Philosophy

Throughout this repository, architectural decisions follow the same principle:

> **Architecture should be driven by system constraints, not by technology preferences.**

The objective is to teach the engineering process behind OTA design rather than promote a specific framework, product, or update mechanism.