Apply structural-param side effects on host automation (#366)

Audio-thread CLAP param events updated the param value but skipped the
reapplyControlSettings / resetSoloState dispatch that the UI path runs,
so automating play mode, polyphony, MPE, sample rate strategy, the
output filters, bit rate, or solo silently failed to reconfigure the
engine. Extract the side-effect block into handleAudioThreadParamSideEffects
and call it from both the UI message path and the CLAP event path. Match
the UI path's int-vs-float discipline so discrete params snap before the
side-effect call sees them.

Assisted-By: Claude Opus 4.7

Author: baconpaul

doc/12_roadmap.md

@@ -2,10 +2,6 @@
 
 I have a lot of ideas for a '1.2' version of six sines. Not 2.0. Still compatible. But expanded. Here's my rough list
 
-## THings which came in after mostly done
-
-- Reset Controls when automated for clap edge for things like sample rate
-
 ## Modulation
 - Clamp targets
 - LFO -> M etc... depth as an additive and attenuation target

src/synth/synth.cpp

@@ -698,26 +698,7 @@ void Synth::processUIQueue(const clap_output_events_t *outq)
                 dest->value = uiM->value;
             }
 
-            /*
-             * Some params have other side effects
-             */
-            if (dest->meta.id == patch.output.playMode.meta.id ||
-                dest->meta.id == patch.output.polyLimit.meta.id ||
-                dest->meta.id == patch.output.pianoModeActive.meta.id ||
-                dest->meta.id == patch.output.mpeActive.meta.id ||
-                dest->meta.id == patch.output.sampleRateStrategy.meta.id ||
-                dest->meta.id == patch.output.resampleEngine.meta.id ||
-                dest->meta.id == patch.output.lowpass.meta.id ||
-                dest->meta.id == patch.output.highpass.meta.id ||
-                dest->meta.id == patch.output.bitRateAdjust.meta.id)
-            {
-                reapplyControlSettings();
-            }
-
-            if (dest->adhocFeatures & Param::AdHocFeatureValues::SOLO)
-            {
-                resetSoloState();
-            }
+            handleAudioThreadParamSideEffects(dest);
 
             auto d = patch.dirty;
             if (!d)
@@ -1075,14 +1056,45 @@ void Synth::handleParamValue(Param *p, uint32_t pid, float value)
         p = patch.paramMap.at(pid);
     }
 
-    // p->value = value;
-    p->lag.setTarget(value);
-    paramLagSet.addToActive(p);
+    // Mirror the UI path (SET_PARAM): only FLOATs lag; discrete params snap so
+    // that handleAudioThreadParamSideEffects sees the new value, not the old.
+    if (p->meta.type == md_t::FLOAT)
+    {
+        p->lag.setTarget(value);
+        paramLagSet.addToActive(p);
+    }
+    else
+    {
+        p->value = value;
+    }
+
+    handleAudioThreadParamSideEffects(p);
 
     AudioToUIMsg au = {AudioToUIMsg::UPDATE_PARAM, pid, value};
     audioToUi.push(au);
 }
 
+void Synth::handleAudioThreadParamSideEffects(Param *dest)
+{
+    if (dest->meta.id == patch.output.playMode.meta.id ||
+        dest->meta.id == patch.output.polyLimit.meta.id ||
+        dest->meta.id == patch.output.pianoModeActive.meta.id ||
+        dest->meta.id == patch.output.mpeActive.meta.id ||
+        dest->meta.id == patch.output.sampleRateStrategy.meta.id ||
+        dest->meta.id == patch.output.resampleEngine.meta.id ||
+        dest->meta.id == patch.output.lowpass.meta.id ||
+        dest->meta.id == patch.output.highpass.meta.id ||
+        dest->meta.id == patch.output.bitRateAdjust.meta.id)
+    {
+        reapplyControlSettings();
+    }
+
+    if (dest->adhocFeatures & Param::AdHocFeatureValues::SOLO)
+    {
+        resetSoloState();
+    }
+}
+
 void Synth::pushFullUIRefresh()
 {
     for (const auto *p : patch.params)

src/synth/synth.h

@@ -522,6 +522,7 @@ struct Synth
 
     void reapplyControlSettings();
     void resetSoloState();
+    void handleAudioThreadParamSideEffects(Param *dest);
 
     sst::cpputils::active_set_overlay<Param> paramLagSet;