# AGENTS.md

Guidance for working in this repository.

## Project

Horizont is a stereo algorithmic reverb audio plugin (VST3 / AU) for macOS.
It pairs a Schroeder/Moorer reverb core (diffusion allpass + parallel damped
combs, gains derived from RT60) with a granular feedback pitch-shifter loop.
Built with JUCE and C++17. See `README.md` for the full DSP description.

## Build & test

From the repo root:

```
make            # fetches JUCE 8.0.15 into ./JUCE if missing, configures + builds (Release)
make install    # installs into ~/Library/Audio/Plug-Ins/VST3 and .../Components
make clean      # delete the build directory
```

- Build artefacts land in `build/Horizont_artefacts/Release/`.
- JUCE must be a **8.0.x release tag** — JUCE 9/master refactored the
  LookAndFeel API and is not supported.
- Configure manually with `cmake -B build -DCMAKE_BUILD_TYPE=Release -DJUCE_ROOT="$(pwd)/JUCE"`.
- There are **no unit tests** in this project. Verify by building, then
  loading the plugin in a host (or `auval` for the AU).
- C++17 only; avoid pre-C++17 and post-C++17 features.

## Layout

```
CMakeLists.txt          build config; new source files must be added here
Makefile                one-command macOS build/install
Source/
  PluginProcessor.*     processor, APVTS, state save/load, host program (presets)
  PluginEditor.*        layout, panels, preset combo box
  HorizontEngine.*      reverb DSP core (allpass diffusers + comb bank + feedback loop)
  PitchShifter.*        granular crossfade pitch shifter
  HorizontLookAndFeel.* dark teal theme, skeuomorphic rotary knobs
  Knob.*                knob component (slider + caption + value readout)
  SpectrumDisplay.*     animated wet/dry spectrum analyser (FFT, timer-driven paint)
  Presets.h             factory presets
```

## Conventions

- Follow JUCE style: `lowerCamelCase` methods/variables, `UpperCamelCase`
  classes, leading-underscore members in some files (match the file you edit).
- Match existing brace/paren style exactly (`juce::` type usage, trailing
  space, tabs for indentation).
- No dynamic allocation in audio callbacks — the processor uses pre-sized
  buffers and `juce::SmoothedValue` for per-sample parameter smoothing.
- All DSP is sample-rate independent: delay lengths, filters, and grain
  windows scale with the sample rate.
- Only add source files after updating `target_sources(...)` in `CMakeLists.txt`.
- Do not add comments unless they explain a non-obvious DSP decision; the
  existing code is mostly self-documenting.
- The UI is a dark teal hardware-rack style; new UI code should match the
  existing palette in `HorizontLookAndFeel.h` / `SpectrumDisplay.cpp` rather
  than introducing new themes.