diff --git a/KJamsClone/DJLoopEditing.swift b/KJamsClone/DJLoopEditing.swift
index 24ab206..62e6015 100644
--- a/KJamsClone/DJLoopEditing.swift
+++ b/KJamsClone/DJLoopEditing.swift
@@ -180,7 +180,7 @@ final class DJNativeSpectrumView: DJWaveMouseView {
     private var hoverX: Double?
     private var tracking: NSTrackingArea?
     override init(frame: NSRect) {
-        super.init(frame:frame)
+        super.init(frame:frame);clipsToBounds = true
         freeze = { [weak self] start in self?.frozenViewport = start;self?.needsDisplay = true }
     }
     required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }
@@ -223,6 +223,12 @@ final class DJNativeSpectrumView: DJWaveMouseView {
         super.mouseDown(with:event)
     }
     override func draw(_ dirtyRect: NSRect) {
+        guard let context = NSGraphicsContext.current?.cgContext else { return }
+        context.saveGState()
+        defer { context.restoreGState() }
+        // Cached sections extend beyond the viewport while scrolling. Neither
+        // those sections nor their markers may paint into adjacent deck controls.
+        context.clip(to:bounds)
         NSColor.black.setFill();bounds.fill()
         guard let player,player.duration > 0,span > 0,!player.waveform.isEmpty else { return }
         let time = player.displayTime,start = frozenViewport ?? (time-span/2),width = bounds.width,height = bounds.height
diff --git a/KJamsClone/DJWorkstation.swift b/KJamsClone/DJWorkstation.swift
index f944256..adbb1ae 100644
--- a/KJamsClone/DJWorkstation.swift
+++ b/KJamsClone/DJWorkstation.swift
@@ -1249,6 +1249,7 @@ struct DJScrollingSpectrum: View {
     var spectralWaveforms = true
     var body: some View {
         DJNativeSpectrum(player:player,bpm:bpm,color:NSColor(color),seconds:seconds,label:label,showTimeGrid:showTimeGrid,spectralWaveforms:spectralWaveforms)
+            .clipped()
             .accessibilityLabel(accessibilityName).accessibilityValue(DJStyle.stamp(player.time))
             .help("Hold the left button and drag left to advance or right to rewind. Shift-drag creates a loop; drag green loop edges to resize or its centre to move it.")
     }
diff --git a/KJamsCloneTests/KJamsCloneTests.swift b/KJamsCloneTests/KJamsCloneTests.swift
index 33b4430..28f28d5 100644
--- a/KJamsCloneTests/KJamsCloneTests.swift
+++ b/KJamsCloneTests/KJamsCloneTests.swift
@@ -2501,3 +2501,42 @@ extension KJamsCloneTests {
         XCTAssertGreaterThan(view.waveformTileBuildCount,builds,"Changing window size must rebuild sharp waveform tiles")
     }
 }
+
+
+extension KJamsCloneTests {
+    @MainActor func testSpectrumCachedSectionsCannotPaintOutsideViewport() async throws {
+        let file = try XCTUnwrap(Bundle(for:Self.self).resourceURL?.appendingPathComponent("Fixtures/Demo.mp3"))
+        let player = Player(persistsMix:false);defer { player.stop() }
+        try player.load(.init(id:1,title:"Clip",audio:file.path,cdg:nil,rating:0,plays:0),startPlaying:false)
+        for _ in 0..<100 where player.waveformLoading { try await Task.sleep(nanoseconds:20_000_000) }
+        let view = DJNativeSpectrumView(frame:NSRect(x:0,y:0,width:300,height:80))
+        view.player = player;view.span = 0.5;view.bpm = 120
+        XCTAssertTrue(view.clipsToBounds)
+        let bitmap = try XCTUnwrap(NSBitmapImageRep(bitmapDataPlanes:nil,pixelsWide:380,pixelsHigh:140,bitsPerSample:8,samplesPerPixel:4,hasAlpha:true,isPlanar:false,colorSpaceName:.deviceRGB,bytesPerRow:0,bitsPerPixel:0))
+        let graphics = try XCTUnwrap(NSGraphicsContext(bitmapImageRep:bitmap))
+        NSGraphicsContext.saveGraphicsState()
+        NSGraphicsContext.current = graphics
+        let context = graphics.cgContext
+        context.setFillColor(CGColor(red:1,green:0,blue:1,alpha:1));context.fill(CGRect(x:0,y:0,width:380,height:140))
+        let sentinel = try XCTUnwrap(bitmap.colorAt(x:0,y:0)?.usingColorSpace(.deviceRGB))
+        context.translateBy(x:40,y:30)
+        for position in [0.25,0.49,0.51,1.0] {
+            player.seek(position)
+            // Deliberately omit AppKit's implicit clipping: draw() must constrain
+            // its own cached tiles, including at a tile-boundary crossing.
+            view.draw(view.bounds)
+        }
+        NSGraphicsContext.restoreGraphicsState()
+        for y in 0..<140 {
+            for x in 0..<380 where x < 40 || x >= 340 || y < 30 || y >= 110 {
+                let color = try XCTUnwrap(bitmap.colorAt(x:x,y:y)?.usingColorSpace(.deviceRGB))
+                guard abs(color.redComponent-sentinel.redComponent) < 0.001,abs(color.greenComponent-sentinel.greenComponent) < 0.001,abs(color.blueComponent-sentinel.blueComponent) < 0.001,abs(color.alphaComponent-sentinel.alphaComponent) < 0.001 else {
+                    return XCTFail("Spectrum drew outside its viewport at \(x),\(y): \(color)")
+                }
+            }
+        }
+        XCTAssertGreaterThan(view.waveformTileBuildCount,0)
+        let inside = try XCTUnwrap(bitmap.colorAt(x:190,y:70)?.usingColorSpace(.deviceRGB))
+        XCTAssertLessThan(inside.redComponent*inside.blueComponent,0.99,"Spectrum must still paint inside its bounds")
+    }
+}