Technical review of the plugin, with its recommended fixes and sound-design measurements

.github/workflows/ci.yml

@@ -42,7 +42,7 @@ jobs:
           "-DCMAKE_OSX_ARCHITECTURES=arm64;x86_64"
 
       - name: Build
-        run: cmake --build build --target voice_allocator_test render_test render_cli ui_test plugin_host_test Drosera_VST3
+        run: cmake --build build --target voice_allocator_test render_test render_cli ui_test plugin_host_test Drosera_VST3 Drosera_AU
 
       - name: Test the release check
         run: python3 tools/test_release_check.py
@@ -65,6 +65,15 @@ jobs:
           unzip -q pluginval.zip -d pluginval-bin
           pluginval-bin/pluginval.app/Contents/MacOS/pluginval --strictness-level 5 --validate-in-process --validate "$VST3"
 
+      # Audio Units are found only in the plugin folders, so install the built one for the runner's user.
+      - name: auval and pluginval on the AU
+        run: |
+          mkdir -p ~/Library/Audio/Plug-Ins/Components
+          ditto build/Drosera_artefacts/Release/AU/Drosera.component ~/Library/Audio/Plug-Ins/Components/Drosera.component
+          killall -9 AudioComponentRegistrar 2>/dev/null || true
+          auval -v aumu Dros Cdsk
+          pluginval-bin/pluginval.app/Contents/MacOS/pluginval --strictness-level 5 --validate-in-process --validate ~/Library/Audio/Plug-Ins/Components/Drosera.component
+
       - name: Check reference renders
         run: tools/hardware-comparison/check_reference.sh build/render_cli
 

CHANGELOG.md

@@ -13,6 +13,24 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/). Ver
 - Echo Pong: a second echo, off by default, whose repeats bounce between left and right and saturate, with PONG, Drive, Tone, Width and Level in its own PONG tab.
 - The Ember Pong preset.
 
+### Fixed
+
+- The echo's first repeats after loading, or after the engine recovers from a bad sample, came late and warped:
+  its delay line started at 5 s and glided towards the knob for seconds, settling up to 3 ms short of it. It now
+  starts at the knob. The three reference renders with echo change throughout, the seven without are byte-identical,
+  so `tools/hardware-comparison/reference/SHA256SUMS` was regenerated.
+- Bypass delays the input by the declared latency, so hosts at rates other than 48 kHz keep the bypassed audio aligned.
+- A host that prepares with a sample rate of 0 no longer makes the resampling buffers unbounded.
+- The noise generator multiplied a signed integer past its range, which is undefined behaviour: it now wraps
+  as unsigned. Same sound.
+- The parameter registry no longer depends on the standard library's hash-map order: its handlers run in a
+  fixed order, the one the reference renders were made with.
+- The Audio Unit is built and validated with `auval` and `pluginval` in CI.
+- JUCE is fetched by commit, not by tag.
+- A restored project takes its parameters at once instead of gliding from the defaults, so it settles on the
+  same drone every time it loads. Presets chosen in the window still glide.
+- The manual says how far Reverb Mix detunes low MIDI notes, from measurement.
+
 ## [0.1.1] - 2026-11-01
 
 ### Fixed

CMakeLists.txt

@@ -47,7 +47,7 @@ if(DROSERA_BUILD_PLUGIN)
     include(FetchContent)
     FetchContent_Declare(JUCE
         GIT_REPOSITORY https://github.com/juce-framework/JUCE.git
-        GIT_TAG 8.0.9
+        GIT_TAG f72bad64d29715216226685810c5196bd0d79d77  # 8.0.9, pinned to the commit: tags can move
         GIT_SHALLOW ON)
     FetchContent_MakeAvailable(JUCE)
 

docs/MANUAL.md

@@ -103,6 +103,9 @@ accepted. While a note is in control:
 - Body is snapped to a whole number of the note's periods, so the Body knob selects a multiple.
 - A band-pass on the note keeps the loop on the fundamental.
 
+Keep Reverb Mix low while playing notes below C3 (note 48): the reverb sits in the loop and pulls low notes out
+of tune, up to about half a semitone at 35 % (see the known limits).
+
 Moving Frequency returns control to the knob once no key is held. A knob moved while a key is down does not take
 pitch back after release: move it again.
 
@@ -169,7 +172,9 @@ others turns POLY off. "Ember Pong" uses PONG and sustains itself, and choosing
   the free drone finds another resonance instead.
 - With MIDI Pitch or LOCK on and Body at about 0.7 or more, a few chord notes sit up to about 60 cents off, at any Coupling,
   on a neighbouring Body resonance.
-- Reverb Mix detunes MIDI notes, because the reverb sits in the loop and its phase is not compensated. With POLY on,
+- Reverb Mix detunes MIDI notes, because the reverb sits in the loop and its phase is not compensated. Measured
+  dry, notes 18 to 84 stay within 17 cents at every Body; at 35 % Mix, notes below 48 read up to 46 cents off
+  (and one case of +105 cents at Body 0.9), while notes from 48 up stay within about 20 cents. With POLY on,
   chords can go sour: with "Chord Keys" otherwise as it is, at Reverb Mix 35 % a C major chord read +20, -28 and -8 cents.
 - The values of "Open Fifths", "Sympathetic", "Chord Keys" and "Ember Pong", and the defaults of Echo Drive, Echo Tone and Echo Level,
   were chosen by measurement and have not been judged by ear.