# Decision 0001: Modular Engine First

**Status:** Accepted

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## Context

The project aims to preserve energyXT's combination of a simple workflow and a
flexible modular routing model.

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## Decision

Use one unified processing graph for sources, instruments, effects, mixers, and
outputs. The sequencer is a timeline/event source integrated with that graph.
The default GUI is simple and sequencer-oriented, while a graph editor exposes
routing when needed.

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## Consequences

- Graph validation, scheduling, buffer allocation, and safe graph replacement
  are foundational requirements.
- Initial audio graph rejects cycles.
- Graph execution plans are prepared off the audio thread.
- The UI must not create a separate routing model disconnected from the engine.