# ADR-000 — HubAudio Engineering Philosophy

**Status:** Accepted

**Date:** 2026-08-01

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## Purpose

HubAudio is designed as a professional embedded platform.

The primary objective is **maintainability**, followed by extensibility, robustness and performance.

The architecture shall minimise cognitive load for future developers.

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# Core Principles

## 1. Code that fits in your head

Every class, function and module shall be understandable in isolation.

If understanding a module requires reading large portions of the codebase, the design should be reconsidered.

Complexity must never be hidden.

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## 2. One Responsibility

Every module has exactly one responsibility.

Examples:

- PowerManager
- DSPManager
- RadioManager
- BluetoothManager
- AudioRouter

Responsibilities shall never overlap.

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## 3. Hardware is software controlled

Every subsystem should, whenever technically possible, support:

- independent power control
- independent reset
- diagnostics
- firmware update

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## 4. Digital-first architecture

Audio remains digital until external conversion is explicitly required.

The DSP is the centre of the audio routing architecture.

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## 5. Documentation is part of the product

Documentation is considered part of the deliverable.

Every architectural decision shall be documented.

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## 6. Simplicity over cleverness

The simplest correct solution is preferred.

Elegant architecture is preferred over clever implementation.

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## 7. Small incremental changes

The project evolves through small, reviewable improvements.

Large architectural changes shall be avoided unless justified.

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# Definition of Done

A feature is considered complete only when:

- implemented
- documented
- testable
- understandable