Add GRID visibility knob and fix spectrum/grid rendering

- Add GRID rotary knob (0-1) controlling grid + axis-label brightness/visibility
- Raise analyser ceiling to 0 dBFS; remove overlapping 0/-6 dB lines
- Set plugin minimum width to 800px (and clamp restored width)
- Extend spectrum signal/peak waves to full plot width
- Render signal wave as quadratic spline to match peak smoothness
- Restore 1px gaps in LED mode

Source/Analyser.h

@@ -70,5 +70,5 @@ private:
     double falloffRate = 0.8;  // normalized units per second while falling
     double barReleaseTau = 0.2; // seconds for the live bar to fall (release)
     double minDb = -48.0;      // dBFS-equivalent floor (bands below this -> 0)
-    double maxDb = -6.0;       // dBFS-equivalent ceiling (bands at/above -> 1)
+    double maxDb = 0.0;        // dBFS-equivalent ceiling (bands at/above -> 1)
 };

Source/AnalyserComponent.h

@@ -34,6 +34,7 @@ public:
         const int    mode     = juce::roundToInt (params.getRawParameterValue ("mode")->load());
         const int    leds     = juce::roundToInt (params.getRawParameterValue ("leds")->load());
         const double smooth   = *params.getRawParameterValue ("smooth");
+        const double gridVis  = *params.getRawParameterValue ("grid");
 
         analyser.setGraceSeconds (graceMs / 1000.0);
         analyser.setFalloffRate (0.1 + falloff * 5.0);
@@ -47,6 +48,7 @@ public:
         displayMode  = mode;
         ledCount     = leds;
         smoothAmount = static_cast<float> (smooth);
+        gridAmount   = static_cast<float> (gridVis);
 
         analyser.update (1.0 / 60.0);
         repaint();
@@ -66,8 +68,8 @@ public:
         const float bandWidth = (plot.getWidth() - gap * (n + 1)) / static_cast<float> (n);
         const float baseY = plot.getBottom();
 
-        const juce::Colour gridColour  = lf.transform (juce::Colours::grey.brighter (0.2f)).withAlpha (0.32f);
-        const juce::Colour labelColour = lf.transform (juce::Colours::grey);
+        const juce::Colour gridColour  = lf.transform (juce::Colours::grey.brighter (0.2f)).withAlpha (gridAmount);
+        const juce::Colour labelColour = gridColour;
 
         // --- Gridlines (drawn first; labels drawn last so they stay readable) ---
         const double freqTicks[] = { 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 20000 };
@@ -179,18 +181,33 @@ private:
         }
 
         // Trace the curve. `smooth` controls how much the band levels are
-        // averaged (above); the path itself is straight segments between band
-        // centres, so at smooth = 0 it stays raw/edgy and at 1 it is rounded
-        // by the heavy level smoothing.
-        juce::Path wave;
-        wave.startNewSubPath (plot.getX() + gap, baseY);
+        // averaged (above); the path itself is a quadratic spline through the
+        // band centres (same technique as the peak wave), so at smooth = 0 it
+        // stays raw/edgy and at 1 it is rounded by the heavy level smoothing.
+        // The curve is anchored to the first/last band value right at the plot
+        // edges so it reaches the full width instead of ramping down to the
+        // baseline at the sides.
+        juce::HeapBlock<juce::Point<float>> wpts (static_cast<size_t> (n));
         for (int i = 0; i < n; ++i)
         {
             const float x = plot.getX() + gap + i * (bandWidth + gap) + bandWidth * 0.5f;
             const float y = baseY - levels[i] * plot.getHeight();
-            wave.lineTo (x, y);
+            wpts[i] = { x, y };
         }
-        wave.lineTo (plot.getRight() - gap, baseY);
+
+        juce::Path wave;
+        wave.startNewSubPath (plot.getX(), wpts[0].y);
+        wave.lineTo (wpts[0]);
+        for (int i = 0; i < n - 1; ++i)
+        {
+            const juce::Point<float> mid = { (wpts[i].x + wpts[i + 1].x) * 0.5f,
+                                             (wpts[i].y + wpts[i + 1].y) * 0.5f };
+            wave.quadraticTo (wpts[i], mid);
+        }
+        wave.quadraticTo (wpts[n - 1], wpts[n - 1]);
+        wave.lineTo (plot.getRight(), wpts[n - 1].y);
+        wave.lineTo (plot.getRight(), baseY);
+        wave.lineTo (plot.getX(), baseY);
         wave.closeSubPath();
 
         // Brighter at the top, darker toward the bottom.
@@ -233,7 +250,8 @@ private:
         }
 
         juce::Path peakWave;
-        peakWave.startNewSubPath (ppts[0]);
+        peakWave.startNewSubPath (plot.getX(), baseY - peaks[0] * plot.getHeight());
+        peakWave.lineTo (ppts[0]);
         for (int i = 0; i < n - 1; ++i)
         {
             const juce::Point<float> mid = { (ppts[i].x + ppts[i + 1].x) * 0.5f,
@@ -241,6 +259,7 @@ private:
             peakWave.quadraticTo (ppts[i], mid);
         }
         peakWave.quadraticTo (ppts[n - 1], ppts[n - 1]);
+        peakWave.lineTo (plot.getRight(), baseY - peaks[n - 1] * plot.getHeight());
         g.setColour (lf.getPeak());
         g.strokePath (peakWave, juce::PathStrokeType (2.0f));
     }
@@ -292,6 +311,7 @@ private:
     int displayMode = ModeBars;
     int ledCount = 16;
     float smoothAmount = 0.35f;
+    float gridAmount = 0.32f;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AnalyserComponent)
 };

Source/PluginEditor.cpp

@@ -13,7 +13,7 @@ BeamgridAudioProcessorEditor::BeamgridAudioProcessorEditor (BeamgridAudioProcess
     // reports IPlugView::canResize() == true to the host, which is what FL
     // Studio (and other hosts) use to enable their native maximize button.
     setResizable (true, true);
-    setResizeLimits (420, 260, 4000, 4000);
+    setResizeLimits (800, 260, 4000, 4000);
 
     analyserComponent.setLookAndFeel (&lookAndFeel);
     addAndMakeVisible (analyserComponent);
@@ -36,6 +36,7 @@ BeamgridAudioProcessorEditor::BeamgridAudioProcessorEditor (BeamgridAudioProcess
     setupKnob (modeSlider, "");
     setupKnob (ledsSlider, "");
     setupKnob (smoothSlider, "");
+    setupKnob (gridSlider, "");
     barsSlider.setNumDecimalPlacesToDisplay (0);
     modeSlider.setNumDecimalPlacesToDisplay (0);
     ledsSlider.setNumDecimalPlacesToDisplay (0);
@@ -80,6 +81,11 @@ BeamgridAudioProcessorEditor::BeamgridAudioProcessorEditor (BeamgridAudioProcess
     smoothLabel.setColour (juce::Label::textColourId, juce::Colours::lightgrey);
     addAndMakeVisible (smoothLabel);
 
+    gridLabel.setText ("GRID", juce::dontSendNotification);
+    gridLabel.setJustificationType (juce::Justification::centred);
+    gridLabel.setColour (juce::Label::textColourId, juce::Colours::lightgrey);
+    addAndMakeVisible (gridLabel);
+
     scaleBox.addItemList (juce::StringArray ("75%", "100%", "150%", "200%", "250%", "300%"), 1);
     scaleBox.setSelectedItemIndex (1); // 100%
     scaleBox.setColour (juce::ComboBox::backgroundColourId, juce::Colours::black.brighter (0.15f));
@@ -127,6 +133,8 @@ BeamgridAudioProcessorEditor::BeamgridAudioProcessorEditor (BeamgridAudioProcess
         processorRef.getParametersState(), "leds", ledsSlider);
     smoothAttachment = std::make_unique<juce::AudioProcessorValueTreeState::SliderAttachment>(
         processorRef.getParametersState(), "smooth", smoothSlider);
+    gridAttachment = std::make_unique<juce::AudioProcessorValueTreeState::SliderAttachment>(
+        processorRef.getParametersState(), "grid", gridSlider);
 
     // Set these AFTER the attachments: SliderAttachment installs its own
     // textFromValueFunction, so assigning afterwards makes ours take effect.
@@ -162,7 +170,7 @@ BeamgridAudioProcessorEditor::BeamgridAudioProcessorEditor (BeamgridAudioProcess
             scaleIdx = i;
     scaleBox.setSelectedItemIndex (scaleIdx); // triggers onChange -> setScaleFactor
 
-    const int storedW = uiState.getProperty ("uiWidth", getWidth());
+    const int storedW = juce::jmax (800, static_cast<int> (uiState.getProperty ("uiWidth", getWidth())));
     const int storedH = uiState.getProperty ("uiHeight", getHeight());
     setSize (storedW, storedH);
 }
@@ -207,7 +215,7 @@ void BeamgridAudioProcessorEditor::resized()
 
     const int margin = 24;
     const int gap = 14;
-    const int count = 8;
+    const int count = 9;
     const int titleW = 220;
 
     // Available width for the knob row (leave room on the right for the title).
@@ -227,6 +235,7 @@ void BeamgridAudioProcessorEditor::resized()
         { modeSlider,        modeLabel },
         { ledsSlider,        ledsLabel },
         { smoothSlider,      smoothLabel },
+        { gridSlider,        gridLabel },
     };
 
     const juce::Font labelFont (juce::FontOptions (11.0f));

Source/PluginEditor.h

@@ -30,6 +30,7 @@ private:
     juce::Slider modeSlider;
     juce::Slider ledsSlider;
     juce::Slider smoothSlider;
+    juce::Slider gridSlider;
 
     juce::Label graceLabel;
     juce::Label falloffLabel;
@@ -39,6 +40,7 @@ private:
     juce::Label modeLabel;
     juce::Label ledsLabel;
     juce::Label smoothLabel;
+    juce::Label gridLabel;
     juce::Label titleLabel;
     juce::Label statusLabel;
 
@@ -52,6 +54,7 @@ private:
     std::unique_ptr<juce::AudioProcessorValueTreeState::SliderAttachment> modeAttachment;
     std::unique_ptr<juce::AudioProcessorValueTreeState::SliderAttachment> ledsAttachment;
     std::unique_ptr<juce::AudioProcessorValueTreeState::SliderAttachment> smoothAttachment;
+    std::unique_ptr<juce::AudioProcessorValueTreeState::SliderAttachment> gridAttachment;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (BeamgridAudioProcessorEditor)
 };

Source/PluginProcessor.cpp

@@ -46,6 +46,11 @@ BeamgridAudioProcessor::createParameterLayout()
         juce::NormalisableRange<float> (0.0f, 1.0f, 0.001f), 0.35f,
         juce::AudioParameterFloatAttributes().withLabel ("")));
 
+    params.push_back (std::make_unique<juce::AudioParameterFloat>(
+        "grid", "Grid Visibility",
+        juce::NormalisableRange<float> (0.0f, 1.0f, 0.001f), 0.32f,
+        juce::AudioParameterFloatAttributes().withLabel ("")));
+
     juce::NormalisableRange<float> barsRange (8.0f, 128.0f,
         [] (float start, float end, float v) { return start + v * (end - start); },        // convertFrom0To1
         [] (float start, float end, float v) { return (v - start) / (end - start); },      // convertTo0To1