xtc/docs/decisions/0002-c-core-fltk-gui.md

Decision 0002: C core with FLTK/C++ GUI

Status: Accepted

Context

The project prioritizes a readable, small C implementation while using FLTK for a lightweight desktop GUI.

Decision

Keep the engine, DSP, project model, graph, and public core API in C (C99 baseline). Use C++ only for FLTK windows and widgets. Communicate through documented C headers with extern "C" guards.

Consequences

• No C++ classes, STL containers, exceptions, or FLTK types cross the C API.
• GUI code cannot mutate engine internals directly.
• Keep C++ simple and limited to the presentation layer.