The more I look at it, the more I realize that the preset management in VST 3 is a totally mixed bag. Different approaches by different plugins, different things supported by hosts, different models declared as possible by the SDK and associated docs.
For most DAWs this isn’t too big a deal… the plugin is configured by the user and that’s it. In Cantabile however where the user might want to switch presets on a state by state basis the behaviour of presets needs to be more deterministic.
One idea I had was to simply make all VST 3 plugins use pseudo presets (ie: a custom bank of presets where each is preset is a snap shot of the entire plugin state). This however could cause problems with slow loading plugins and plugins where the preset model actually works as expected.
This also crosses paths another an idea I had for lightweight presets where just the automation parameters are captured in each preset.
So I’m going to set VST 3 work aside for bit, take a look at adding support for different preset models and then return here once Cantabile is better equipped to handle VST 3’s preset handling.