refactor: unify component type dispatch + decompose RfSimulatorApp (#51)

adc/include/adc_engine.h

@@ -12,6 +12,7 @@ class AdcEngine : public IComponentEngine {
 
     int id() const override { return m_id; }
     int graphNodeId() const override { return m_graph_node_id; }
+    std::string_view type_name() const override { return "adc"; }
     std::string hoverSummary() const override;
     int inputPinId() const override;
     int outputPinId() const override;

adc/src/adc_engine.cpp

@@ -120,7 +120,8 @@ nlohmann::json AdcEngine::serialize() const {
 }
 
 void AdcEngine::deserialize(const nlohmann::json &j) {
-    m_fs_Hz = j.value("sample_rate_Hz", 1e9);
+    m_fs_Hz =
+        j.contains("sample_rate_Hz") ? j["sample_rate_Hz"].get<double>() : j.value("fs_Hz", 1e9);
     m_nsd_dBm_per_Hz = j.value("nsd_dBm_per_Hz", -155.0);
     m_dirty = true;
 }

amplifier/include/amplifier_engine.h

@@ -12,6 +12,7 @@ class AmplifierEngine : public IComponentEngine {
     AmplifierEngine(int id, NodeGraphEngine &graph);
     int id() const override { return m_id; }
     int graphNodeId() const override { return m_graph_node_id; }
+    std::string_view type_name() const override { return "amplifier"; }
     std::string hoverSummary() const override;
     int inputPinId() const override;
     int outputPinId() const override;

amplifier/src/amplifier_engine.cpp

@@ -216,9 +216,16 @@ void AmplifierEngine::deserialize(const nlohmann::json &j) {
     m_gain_dB = j.value("gain_dB", 0.0);
     m_nf_dB = j.value("nf_dB", 0.0);
     m_nonlinear.setEnabled(j.value("enable_nonlinear", false));
-    m_nonlinear.setOIP2_dBm(j.value("oip2_dBm", 50.0));
-    m_nonlinear.setOIP3_dBm(j.value("oip3_dBm", 50.0));
+    m_nonlinear.setOIP2_dBm(j.value("oip2_dBm", 100.0));
+    m_nonlinear.setOIP3_dBm(j.value("oip3_dBm", 100.0));
     m_nonlinear.setP1dB_dBm(j.value("p1db_dBm", 100.0));
+    // Library definitions (schema v1/v2) omit `enable_nonlinear` but include
+    // OIP/P1dB params. The old registry factory enabled nonlinearity whenever
+    // any of those were present; project files always serialize the explicit
+    // key, so only fall back when it is absent.
+    if (!j.contains("enable_nonlinear") &&
+        (j.contains("oip2_dBm") || j.contains("oip3_dBm") || j.contains("p1db_dBm")))
+        m_nonlinear.setEnabled(true);
     m_sparam_mode = j.value("sparam_mode", false);
     m_sparam_filepath = j.value("sparam_filepath", "");
     m_sparam_fwd_idx = j.value("sparam_fwd_idx", 0);

app/AGENTS.md

@@ -1,18 +1,20 @@
 # app/AGENTS.md
 
 ## Purpose
-Application orchestrator layer containing `RfSimulatorApp`, `ComponentRegistry`, and `InspectorPanel`.
+Application orchestrator layer containing `RfSimulatorApp`, `ComponentRegistry`, `ComponentTypeRegistry`, `InspectorPanel`, `PFBViewManager`, and `ProjectSerializer`.
 
 ## Ownership
-- `RfSimulatorApp` — application boot, frame loop, DSP update, UI orchestration, project save/load
+- `RfSimulatorApp` — application boot, frame loop, DSP update, UI orchestration (project save/load logic lives in `ProjectSerializer`)
 - `ComponentRegistry` — polymorphic component lifecycle and type-indexed lookup
 - `InspectorPanel` — property editing panel with dirty tracking
-- `ComponentTypeRegistry` — data-driven type schema table (field lists + factories) used by `ComponentLibrary::instantiate()`/`validate()` and the component authoring form
+- `ComponentTypeRegistry` — single dispatch table (11 rows) for canvas menu, add, duplicate, save/load, and inspector drawing: each row carries the canonical `type` + `.rfsim` `project_type` keys, `menu_label`/`label_prefix`, `NodeKind`, a `create()` factory, and a `draw_inspector` callback; also drives `ComponentLibrary::instantiate()`/`validate()` and the component authoring form
+- `PFBViewManager` — owns the per-PFB IQ Plot / Channelizer Grid widget lifecycle (replaces the app's four lockstep vectors `m_iq_widgets`/`m_show_iq_pfbs`/`m_pfb_grid_widgets`/`m_show_pfb_grids`, which were rebuilt by hand at six call sites and caused issue #37); all add/rebuild/clear/draw and visibility state funnel through this class
+- `ProjectSerializer` — owns the `.rfsim` save/load/new JSON logic (extracted from `RfSimulatorApp`, issue #51)
 - `ComponentFormModel` / `ComponentFormWidget` — pure-logic + ImGui rendering pair for the New/Edit Component form
 - `ExtensionManager` — extension manifest discovery and status tracking across built-in/global/project-local roots
 - `ExternalToolRunner` — structured request/result execution for approved external tools
 ## Local Contracts
-- `saveProject()` / `loadProject()` / `newProject()` handle full project serialization to `.rfsim` JSON format
+- `RfSimulatorApp::saveProject()` / `loadProject()` / `newProject()` are thin wrappers that delegate to `ProjectSerializer::save()` / `load()` / `reset()`; all `.rfsim` JSON serialization lives in `ProjectSerializer`
 - Dirty tracking propagated via `markDirty()` / `onParamChange` / `onLinkChanged` callbacks
 - File menu bar in `draw_ui()` handles keyboard shortcuts (`Ctrl+N`, `Ctrl+O`, `Ctrl+S`, `Ctrl+Shift+S`) and unsaved-changes modal; Help menu provides F1-toggled help window
 - View menu's `Layouts` submenu (Save As.../Load/Manage...) drives `LayoutManager` (see `layout/AGENTS.md`) for named window-layout presets; the exe-relative default layout is auto-managed by ImGui itself via `IniFilename`, set in `core/src/core.cpp`
@@ -25,12 +27,12 @@ Application orchestrator layer containing `RfSimulatorApp`, `ComponentRegistry`,
 - `draw_ui()` and `drawExtensionsPanel()` both dispatch through `externalToolActions()`; the Tools menu renders only actions whose `location == "tools"`, while the Extensions panel shows every declared action (or a single fallback Run button)
 - App-level integration tests may use `testExtensionManager()` and `testExtensionResultMessage()` with an ImGui/ImPlot/ImNodes fixture
 - `load_window_states()` runs on construction to restore persisted window visibility toggles
-- Per-PFB IQ Plot / Channelizer Grid window visibility (`m_show_iq_pfbs`/`m_show_pfb_grids`, indexed in lockstep with `m_pfb_ptrs`) has no View-menu entry since instances are dynamic; closed windows are reopened via "Show IQ Plot"/"Show Channelizer Grid" checkboxes in the PFB properties panel, wired each frame through `InspectorPanel::setPFBWindowVisibility()` (stores the stable vector pointers, not element pointers, since the vectors are rebuilt on add/remove)
+- Per-PFB IQ Plot / Channelizer Grid window visibility lives in `PFBViewManager::iqVisibility()`/`gridVisibility()` (indexed in lockstep with the manager's widgets) and has no View-menu entry since instances are dynamic; closed windows are reopened via "Show IQ Plot"/"Show Channelizer Grid" checkboxes in the PFB properties panel, wired each frame through `InspectorPanel::setPFBWindowVisibility()` (stores the stable vector pointers, not element pointers, since the vectors are rebuilt on add/remove)
 - `update_dsp()`'s signal-routing pass is factored into `rewireInputs()` (sets every component's `node().inputs[k]` from current graph links, nulling severed ones); `onRemoveNode` calls it synchronously right after `ComponentRegistry::remove()` so no surviving component is left holding a dangling `Spectrum*` into the just-destroyed engine's `SignalNode` while the rest of that frame's `draw_ui()` still runs — widgets that dereference `node().inputs[]` directly during draw (e.g. `PFBChannelizerWidget`) would otherwise use-after-free (issue #37)
 - Destructor saves window state via `SessionState`
 
 ## Work Guidance
-- Add new component serialization in both `saveProject()` (dump to JSON) and `loadProject()` (read from JSON + create via `ComponentRegistry`)
+- Add a new component = one `ComponentTypeRegistry` row (`type`, `project_type`, `menu_label`, `label_prefix`, `kind`, `create`, `draw_inspector`) + a `NodeKind`/symbol entry in `node_graph` — the menu, add, duplicate, save/load, inspector, and form paths all dispatch through the registry, so no per-file edits in `RfSimulatorApp` are needed
 
 ## Verification
 - Round-trip tests in `tests/test_project_file.cpp`

app/CMakeLists.txt

@@ -17,6 +17,8 @@ add_library(app STATIC
     src/extension_manifest.cpp
     src/extension_manager.cpp
     src/external_tool_runner.cpp
+    src/pfb_view_manager.cpp
+    src/project_serializer.cpp
 )
 add_library(simulator::app ALIAS app)
 

app/include/app.h

@@ -25,6 +25,8 @@
 #include "node_graph_widget.h"
 #include "pfb_channelizer_engine.h"
 #include "pfb_channelizer_widget.h"
+#include "pfb_view_manager.h"
+#include "project_serializer.h"
 #include "session_state.h"
 #include "signal_generator_engine.h"
 #include "signal_generator_widget.h"
@@ -93,6 +95,7 @@ class RfSimulatorApp {
     void load_window_states();
     void rewireInputs();
     void duplicateComponent(int graph_node_id);
+    void addComponent(const ComponentTypeDescriptor *desc, ImVec2 pos);
     void openNewComponentForm(const std::string &type);
     void openEditComponentForm(const ComponentDefinition &def);
     void drawComponentFormModal();
@@ -104,9 +107,6 @@ class RfSimulatorApp {
     std::unique_ptr<NodeGraphWidget> m_graph_widget;
 
     std::vector<std::unique_ptr<SignalGeneratorWidget>> m_generator_widgets;
-    std::vector<std::unique_ptr<IQPlotWidget>> m_iq_widgets;
-    std::vector<bool> m_show_iq_pfbs;
-    std::vector<std::unique_ptr<PFBChannelizerWidget>> m_pfb_grid_widgets;
     ComponentLibrary m_library;
     std::unique_ptr<LibraryBrowserWidget> m_library_browser;
     bool m_show_library = false;
@@ -116,10 +116,15 @@ class RfSimulatorApp {
     std::unique_ptr<ComponentFormModel> m_component_form_model;
     std::unique_ptr<ComponentFormWidget> m_component_form_widget;
     std::string m_component_form_error;
-    std::vector<bool> m_show_pfb_grids;
     std::unique_ptr<InspectorPanel> m_inspector_panel;
 
     ComponentRegistry m_components;
+    // Declared after m_components so the manager (and its widget references to
+    // engines) is destroyed before the engines themselves.
+    PFBViewManager m_pfb_views;
+    // Owns .rfsim save/load/new; declared after m_graph_widget and m_pfb_views
+    // so it is destroyed before them (it holds references to both).
+    std::unique_ptr<ProjectSerializer> m_serializer;
     int m_next_component_id = 100;
     PendingAction m_pending_action = PendingAction::None;
     bool m_show_unsaved_dialog = false;

app/include/component_type_registry.h

@@ -1,15 +1,17 @@
-// app/include/component_type_registry.h
 #pragma once
 
+#include "node_graph_engine.h"
 #include <functional>
 #include <limits>
 #include <nlohmann/json.hpp>
 #include <string>
+#include <string_view>
 #include <vector>
 
 class ComponentRegistry;
 class NodeGraphEngine;
 class IComponentEngine;
+class InspectorPanel;
 
 enum class FieldKind { Number, String, Enum, FilePath, Bool };
 
@@ -27,21 +29,31 @@ struct ParameterField {
 };
 
 struct ComponentTypeDescriptor {
-    std::string type;         // "amplifier"
-    std::string display_name; // "Amplifier"
-    std::vector<ParameterField> fields;
+    std::string type;         // canonical key, e.g. "amplifier"
+    std::string project_type; // .rfsim save/load name, e.g. "Amplifier"
+    std::string display_name; // e.g. "Amplifier"
+    std::string menu_label;   // canvas menu item, e.g. "Add Amplifier"
+    std::string label_prefix; // graph label prefix, e.g. "Amplifier"
+    NodeKind kind = NodeKind::Unknown;
+    bool authorable = false; // appears in New Component form combo
     bool supports_sparam_file = false;
-    std::function<IComponentEngine *(ComponentRegistry &, NodeGraphEngine &, int,
-                                     const nlohmann::json &)>
-        factory;
+    std::vector<ParameterField> fields;
+
+    // Create a default engine of this type (no params). Callers apply params
+    // via engine->deserialize().
+    std::function<IComponentEngine *(ComponentRegistry &, NodeGraphEngine &, int)> create;
+    // Inspector property draw. Receives the panel so PFB's multi-instance
+    // selector and dirty-flag state stay reachable.
+    std::function<void(InspectorPanel &, IComponentEngine &)> draw_inspector;
 };
 
 class ComponentTypeRegistry {
   public:
-    static const ComponentTypeRegistry &instance();
+    static ComponentTypeRegistry &instance();
 
-    const ComponentTypeDescriptor *find(const std::string &type) const;
-    std::vector<const ComponentTypeDescriptor *> all() const;
+    const ComponentTypeDescriptor *find(std::string_view type) const;
+    const ComponentTypeDescriptor *findByProjectType(std::string_view name) const;
+    std::vector<ComponentTypeDescriptor *> all();
 
   private:
     ComponentTypeRegistry();

app/include/inspector_panel.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "component_interface.h"
+#include "component_type_registry.h"
 #include "node_graph_engine.h"
 #include "signal_node.h"
 #include <functional>
@@ -35,9 +36,17 @@ class InspectorPanel {
 
     void draw(const char *title, bool *p_open = nullptr);
     void setPFBs(const std::vector<PFBChannelizerEngine *> &pfbs) {
+        const bool selection_survives =
+            m_selected_pfb_index >= 0 && m_selected_pfb_index < static_cast<int>(pfbs.size()) &&
+            m_selected_pfb_index < static_cast<int>(m_pfb_ptrs.size()) &&
+            pfbs[m_selected_pfb_index] == m_pfb_ptrs[m_selected_pfb_index];
         m_pfb_ptrs = pfbs;
         if (m_selected_pfb_index >= static_cast<int>(m_pfb_ptrs.size()))
             m_selected_pfb_index = std::max(0, static_cast<int>(m_pfb_ptrs.size()) - 1);
+        // A PFB was added/removed and the combo selection did not survive the
+        // reshuffle: drop the anchor so draw() re-follows the graph selection.
+        if (!selection_survives)
+            m_pfb_combo_graph_id = -1;
     }
     // Vectors are owned by the caller (RfSimulatorApp) and stay stable across frames;
     // only their contents are rebuilt on add/remove, so storing the vector pointers
@@ -52,46 +61,40 @@ class InspectorPanel {
     void setViewToggles(const ViewToggles &t) { m_viewToggles = t; }
     bool m_param_edited = false;
 
+    // Called once at startup; wires ComponentTypeRegistry draw_inspector
+    // callbacks to this panel's property drawers.
+    void registerDrawers(ComponentTypeRegistry &registry);
+
+    void drawAmplifierProperties(AmplifierEngine &engine, int index);
+    void drawCoaxCableProperties(CoaxCableEngine &engine, int index);
+    void drawEqualizerProperties(EqualizerEngine &engine, int index);
+    void drawMixerProperties(MixerEngine &engine, int index);
+    void drawSplitterProperties(SplitterEngine &engine, int index);
+    void drawAdcProperties(AdcEngine &engine, int index);
+    void drawGeneratorProperties(SignalGeneratorEngine &engine, int index);
+    void drawPFBProperties(PFBChannelizerEngine &engine);
+    void drawIdealFilterProperties(IdealFilterEngine &engine, int index);
+    void drawAttenuatorProperties(AttenuatorEngine &engine, int index);
+    void drawCombinerProperties(CombinerEngine &engine, int index);
+    void drawGroupPanel(int group_id);
+
   private:
     NodeGraphEngine &m_graph;
     ComponentRegistry *m_components = nullptr;
     std::vector<PFBChannelizerEngine *> m_pfb_ptrs;
     int m_selected_pfb_index = 0;
+    // Graph-selected PFB id that the combo selection is anchored to; -1 means
+    // draw() must re-follow the graph selection (initial state, or after the
+    // PFB set changed underneath the selection).
+    int m_pfb_combo_graph_id = -1;
     ViewToggles m_viewToggles;
     std::vector<bool> *m_pfb_iq_visible = nullptr;
     std::vector<bool> *m_pfb_grid_visible = nullptr;
 
-    enum class ComponentType {
-        None,
-        Generator,
-        Amplifier,
-        Splitter,
-        Mixer,
-        Adc,
-        PFB,
-        IdealFilter,
-        CoaxCable,
-        Equalizer,
-        Attenuator,
-        Combiner
-    };
     struct Hit {
-        ComponentType type;
+        const ComponentTypeDescriptor *desc = nullptr;
         IComponentEngine *engine = nullptr;
     };
     Hit findSelected() const;
     std::string labelForHit(const Hit &hit) const;
-
-    void drawAmplifierProperties(AmplifierEngine &engine, int index);
-    void drawCoaxCableProperties(CoaxCableEngine &engine, int index);
-    void drawEqualizerProperties(EqualizerEngine &engine, int index);
-    void drawMixerProperties(MixerEngine &engine, int index);
-    void drawSplitterProperties(SplitterEngine &engine, int index);
-    void drawAdcProperties(AdcEngine &engine, int index);
-    void drawGeneratorProperties(SignalGeneratorEngine &engine, int index);
-    void drawPFBProperties(PFBChannelizerEngine &engine);
-    void drawIdealFilterProperties(IdealFilterEngine &engine, int index);
-    void drawAttenuatorProperties(AttenuatorEngine &engine, int index);
-    void drawCombinerProperties(CombinerEngine &engine, int index);
-    void drawGroupPanel(int group_id);
 };

app/include/pfb_view_manager.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include "iq_plot_widget.h"
+#include "pfb_channelizer_engine.h"
+#include "pfb_channelizer_widget.h"
+#include <memory>
+#include <vector>
+
+class ComponentRegistry;
+class SessionState;
+
+// Owns the per-PFB view widgets and their visibility flags. The app's old
+// four lockstep vectors (m_iq_widgets/m_show_iq_pfbs/m_pfb_grid_widgets/
+// m_show_pfb_grids) were rebuilt by hand at six call sites and caused issue
+// #37 (use-after-free). All lifecycle now funnels through this class.
+class PFBViewManager {
+  public:
+    void addFor(PFBChannelizerEngine &engine, SessionState &state);
+    void rebuild(const ComponentRegistry &components, SessionState &state);
+    void clear();
+    void draw();
+    void saveVisibility(const ComponentRegistry &components, SessionState &state) const;
+
+    std::vector<bool> &iqVisibility() { return m_show_iq_pfbs; }
+    std::vector<bool> &gridVisibility() { return m_show_pfb_grids; }
+
+  private:
+    std::vector<std::unique_ptr<IQPlotWidget>> m_iq_widgets;
+    std::vector<bool> m_show_iq_pfbs;
+    std::vector<std::unique_ptr<PFBChannelizerWidget>> m_pfb_grid_widgets;
+    std::vector<bool> m_show_pfb_grids;
+};

app/include/project_serializer.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <string>
+
+class ComponentRegistry;
+class NodeGraphEngine;
+class NodeGraphWidget;
+class PFBViewManager;
+class SessionState;
+
+// Owns the .rfsim JSON save/load/new logic previously inlined in
+// RfSimulatorApp (issue #51: 1320-line god-object).
+class ProjectSerializer {
+  public:
+    ProjectSerializer(ComponentRegistry &components, NodeGraphEngine &graph,
+                      NodeGraphWidget &graph_widget, PFBViewManager &pfb_views, SessionState &state,
+                      int &next_component_id, bool &show_log, bool &show_spectrum,
+                      bool &show_properties, bool &show_node_editor);
+
+    void save(const std::string &path);
+    bool load(const std::string &path); // false on parse/unknown-type failure (logged)
+    void reset();                       // newProject: links, components, probes, counters, PFBs
+
+  private:
+    ComponentRegistry &m_components;
+    NodeGraphEngine &m_graph;
+    NodeGraphWidget &m_graph_widget;
+    PFBViewManager &m_pfb_views;
+    SessionState &m_state;
+    int &m_next_component_id;
+    bool &m_show_log;
+    bool &m_show_spectrum;
+    bool &m_show_properties;
+    bool &m_show_node_editor;
+};