Ensure IONode's Parent Graph Has a Minimum Channel Count

.github/copilot-instructions.md

@@ -12,3 +12,11 @@
 - Write clear, readable code with descriptive names for variables, functions, and classes.
 - Maintain consistency with the existing codebase style and patterns.
 - Consider maintainability and future developers who will read the code.
+
+## Audio Graph Architecture
+
+- **IONodes** (audio/MIDI input/output) require a parent `GraphNode` to be set before ports can be properly initialized.
+- `IONode::refreshPorts()` queries the parent graph's port count via `graph->getNumPorts()`. If the parent is null or has zero ports, the IONode will have zero ports.
+- When adding IONodes, ensure the parent graph has a valid port count first using `graph->setNumPorts()`.
+- Default port counts: 2 channels for audio (stereo), 1 channel for MIDI.
+- Message flow for adding nodes: `AddPluginMessage` → `AddPluginAction::perform()` → `EngineService::addPlugin()` → `GraphManager::addNode()`.

src/engine/ionode.cpp

@@ -183,6 +183,20 @@ bool IONode::isOutput() const { return type == audioOutputNode || type == midiOu
 void IONode::setParentGraph (GraphNode* const newGraph)
 {
     graph = newGraph;
+
+    // Ensure the parent graph has a minimum port count for this IONode's type.
+    // Default: 2 channels for audio (stereo), 1 channel for MIDI.
+    if (graph != nullptr)
+    {
+        const auto portType = getPortType();
+        const int currentCount = graph->getNumPorts (portType, isInput());
+        if (currentCount == 0)
+        {
+            const int defaultCount = (portType == PortType::Audio) ? 2 : 1;
+            graph->setNumPorts (portType, defaultCount, isInput(), false);
+        }
+    }
+
     refreshPorts();
 }
 

test/audioroutingtests.cpp

@@ -1032,4 +1032,33 @@ BOOST_AUTO_TEST_CASE (AudioFeedbackPrevention)
     BOOST_REQUIRE (! feedbackAllowed);
 }
 
+BOOST_AUTO_TEST_CASE (IONodeMinimumAudioPortCount)
+{
+    // Test that Audio I/O nodes get a minimum port count when added to a graph with zero audio ports
+    // This prevents the bug where Audio Input/Output nodes appear with zero ports
+
+    PreparedGraph fix;
+    GraphNode& graph = fix.graph;
+
+    fix.graph.clear();
+    graph.setNumPorts (PortType::Audio, 0, true, false);
+    graph.setNumPorts (PortType::Audio, 0, false, false);
+
+    // Verify graph starts with zero audio ports configured
+    BOOST_REQUIRE_EQUAL (graph.getNumPorts (PortType::Audio, true), 0);
+    BOOST_REQUIRE_EQUAL (graph.getNumPorts (PortType::Audio, false), 0);
+
+    // Add Audio Input node - should set graph audio inputs to minimum 2 (stereo)
+    auto* audioIn = new IONode (IONode::audioInputNode);
+    graph.addNode (audioIn);
+    BOOST_REQUIRE_EQUAL (graph.getNumPorts (PortType::Audio, true), 2);
+    BOOST_REQUIRE_EQUAL (audioIn->getNumPorts(), 2);
+
+    // Add Audio Output node - should set graph audio outputs to minimum 2 (stereo)
+    auto* audioOut = new IONode (IONode::audioOutputNode);
+    graph.addNode (audioOut);
+    BOOST_REQUIRE_EQUAL (graph.getNumPorts (PortType::Audio, false), 2);
+    BOOST_REQUIRE_EQUAL (audioOut->getNumPorts(), 2);
+}
+
 BOOST_AUTO_TEST_SUITE_END()