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+# ADR-000 — HubAudio Engineering Philosophy
+
+**Status:** Accepted
+
+**Date:** 2026-08-01
+
+---
+
+## 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.
+
+---
+
+# 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.
+
+---
+
+## 2. One Responsibility
+
+Every module has exactly one responsibility.
+
+Examples:
+
+- PowerManager
+- DSPManager
+- RadioManager
+- BluetoothManager
+- AudioRouter
+
+Responsibilities shall never overlap.
+
+---
+
+## 3. Hardware is software controlled
+
+Every subsystem should, whenever technically possible, support:
+
+- independent power control
+- independent reset
+- diagnostics
+- firmware update
+
+---
+
+## 4. Digital-first architecture
+
+Audio remains digital until external conversion is explicitly required.
+
+The DSP is the centre of the audio routing architecture.
+
+---
+
+## 5. Documentation is part of the product
+
+Documentation is considered part of the deliverable.
+
+Every architectural decision shall be documented.
+
+---
+
+## 6. Simplicity over cleverness
+
+The simplest correct solution is preferred.
+
+Elegant architecture is preferred over clever implementation.
+
+---
+
+## 7. Small incremental changes
+
+The project evolves through small, reviewable improvements.
+
+Large architectural changes shall be avoided unless justified.
+
+---
+
+# Definition of Done
+
+A feature is considered complete only when:
+
+- implemented
+- documented
+- testable
+- understandable
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