diff --git a/src/common/serialization/vst3/README.md b/src/common/serialization/vst3/README.md
index a6d10363..c626bb36 100644
--- a/src/common/serialization/vst3/README.md
+++ b/src/common/serialization/vst3/README.md
@@ -19,11 +19,14 @@ VST3 plugin interfaces are implemented as follows:
VST3 host interfaces are implemented as follows:
-| yabridge class | Interfaces |
-| ------------------- | ------------------ |
-| `YaHostApplication` | `IHostApplication` |
+| yabridge class | Included in | Interfaces |
+| --------------------------- | --------------------------- | ------------------- |
+| `YaHostApplication` | | `IHostApplication` |
+| `Vst3ComponentHandlerProxy` | | All of the below: |
+| `YaComponentHandler` | `Vst3ComponentHandlerProxy` | `IComponentHandler` |
-The following (host) interfaces are also implemented for serialization purposes:
+The following host interfaces are passed as function arguments and are thus also
+implemented for serialization purposes:
| yabridge class | Interfaces | Notes |
| -------------------- | ------------------- | ---------------------------------------------------------------------- |
diff --git a/src/common/serialization/vst3/component-handler-proxy.h b/src/common/serialization/vst3/component-handler-proxy.h
new file mode 100644
index 00000000..597d6219
--- /dev/null
+++ b/src/common/serialization/vst3/component-handler-proxy.h
@@ -0,0 +1,115 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see .
+
+#pragma once
+
+#include "../common.h"
+#include "base.h"
+#include "host-application.h"
+#include "plugin/audio-processor.h"
+#include "plugin/component.h"
+#include "plugin/connection-point.h"
+#include "plugin/edit-controller.h"
+#include "plugin/plugin-base.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * An abstract class that implements `IComponentHandler`, and optionally also
+ * all other VST3 interfaces an object passed to
+ * `IEditController::setComponentHandler()`. This works exactly the same as
+ * `Vst3PluginProxy`, but instead of proxying for an object provided by the
+ * plugin we are proxying for the `IComponentHandler*` argument passed to plugin
+ * by the host.
+ */
+class Vst3ComponentHandlerProxy {
+ public:
+ /**
+ * These are the arguments for constructing a
+ * `Vst3ComponentHandlerProxyImpl`.
+ */
+ struct ConstructArgs {
+ ConstructArgs();
+
+ /**
+ * Read from an existing object. We will try to mimic this object, so
+ * we'll support any interfaces this object also supports.
+ */
+ ConstructArgs(Steinberg::IPtr object,
+ size_t owner_instance_id);
+
+ /**
+ * The unique instance identifier of the proxy object instance this
+ * component handler has been passed to and thus belongs to. This way we
+ * can refer to the correct 'actual' `IComponentHandler` instance when
+ * the plugin does a callback.
+ */
+ native_size_t owner_instance_id;
+
+ // TODO:
+ // YaAudioProcessor::ConstructArgs audio_processor_args;
+ // YaComponent::ConstructArgs component_args;
+ // YaConnectionPoint::ConstructArgs connection_point_args;
+ // YaEditController::ConstructArgs edit_controller_2_args;
+ // YaPluginBase::ConstructArgs plugin_base_args;
+
+ template
+ void serialize(S& s) {
+ s.value8b(owner_instance_id);
+ // TODO:
+ // s.object(audio_processor_args);
+ // s.object(component_args);
+ // s.object(connection_point_args);
+ // s.object(edit_controller_2_args);
+ // s.object(plugin_base_args);
+ }
+ };
+
+ /**
+ * Instantiate this instance with arguments read from an actual component
+ * handler.
+ *
+ * @note Since this is passed as part of
+ * `IEditController::setComponentHandler()`, there are no direct
+ * `Construct` or `Destruct` messages. This object's lifetime is bound to
+ * that of the objects they are passed to. If those objects get dropped,
+ * then the host contexts should also be dropped.
+ */
+ Vst3ComponentHandlerProxy(const ConstructArgs&& args);
+
+ /**
+ * The lifetime of this object should be bound to the object we created it
+ * for. When for instance the `Vst3PluginProxy` instance with id `n` gets
+ * dropped a corresponding `Vst3ComponentHandlerProxyImpl` should also be
+ * dropped.
+ */
+ virtual ~Vst3ComponentHandlerProxy() = 0;
+
+ DECLARE_FUNKNOWN_METHODS
+
+ /**
+ * Get the instance ID of the owner of this object.
+ */
+ inline size_t owner_instance_id() const {
+ return arguments.owner_instance_id;
+ }
+
+ private:
+ ConstructArgs arguments;
+};
+
+#pragma GCC diagnostic pop
diff --git a/src/common/serialization/vst3/host-application.h b/src/common/serialization/vst3/host-application.h
index 9ad1a586..122c5f94 100644
--- a/src/common/serialization/vst3/host-application.h
+++ b/src/common/serialization/vst3/host-application.h
@@ -90,8 +90,8 @@ class YaHostApplication : public Steinberg::Vst::IHostApplication {
/**
* The lifetime of this object should be bound to the object we created it
* for. When for instance the `Vst3PluginProxy` instance with id `n` gets
- * dropped and we also track a `YaHostApplicationImpl` for the component
- * with instance id `n`, then that should also be dropped.
+ * dropped, the corresponding `YaHostApplicationImpl` then that should also
+ * be dropped.
*/
virtual ~YaHostApplication();
diff --git a/src/common/serialization/vst3/plugin-proxy.h b/src/common/serialization/vst3/plugin-proxy.h
index fe60da24..0fe9776e 100644
--- a/src/common/serialization/vst3/plugin-proxy.h
+++ b/src/common/serialization/vst3/plugin-proxy.h
@@ -17,11 +17,8 @@
#pragma once
#include
-#include
#include "../common.h"
-#include "base.h"
-#include "host-application.h"
#include "plugin/audio-processor.h"
#include "plugin/component.h"
#include "plugin/connection-point.h"