diff --git a/Package.swift b/Package.swift
index 7c1edb8..0fee76c 100644
--- a/Package.swift
+++ b/Package.swift
@@ -24,7 +24,11 @@ let package = Package(
         // Targets are the basic building blocks of a package, defining a module or a test suite.
         // Targets can depend on other targets in this package and products from dependencies.
         .target(
-            name: "TextDiff"),
+            name: "TextDiff",
+            swiftSettings: [
+                .define("TESTING", .when(configuration: .debug))
+            ]
+        ),
         .testTarget(
             name: "TextDiffTests",
             dependencies: [
diff --git a/README.md b/README.md
index 7f68c03..c8b2d25 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # TextDiff
 
-TextDiff is a macOS Swift package that computes token-level diffs and renders a merged, display-only SwiftUI view backed by a custom AppKit renderer.
+TextDiff is a macOS Swift package that computes token-level diffs and renders a merged, display-only diff view for both SwiftUI (`TextDiffView`) and AppKit (`NSTextDiffView`) via the same custom AppKit renderer.
 
 ![TextDiff preview](Resources/textdiff-preview.png)
 
@@ -43,6 +43,30 @@ struct DemoView: View {
 }
 ```
 
+## AppKit Usage
+
+```swift
+import AppKit
+import TextDiff
+
+let diffView = NSTextDiffView(
+    original: "This is teh old sentence.",
+    updated: "This is the updated sentence!",
+    mode: .token
+)
+
+// Constrain width in your layout. Height is intrinsic and computed from width.
+diffView.translatesAutoresizingMaskIntoConstraints = false
+```
+
+You can update content in place:
+
+```swift
+diffView.mode = .character
+diffView.original = "Add a diff"
+diffView.updated = "Added a diff"
+```
+
 ## Comparison Modes
 
 ```swift
@@ -101,14 +125,15 @@ struct StyledDemoView: View {
 - No synthetic spacer characters are inserted into the rendered text stream.
 - Chip top/bottom clipping is prevented internally via explicit line-height and vertical content insets.
 - Moved text is not detected as a move; it appears as delete + insert.
-- Rendering uses a custom AppKit draw view bridged into SwiftUI.
+- Rendering uses a custom AppKit draw view shared by both `TextDiffView` and `NSTextDiffView`.
 
 ## Snapshot Testing
 
 Snapshot coverage uses [Point-Free SnapshotTesting](https://github.com/pointfreeco/swift-snapshot-testing) with `swift-testing`.
 
 - Snapshot tests live in `Tests/TextDiffTests/TextDiffSnapshotTests.swift`.
-- Baselines are stored under `Tests/TextDiffTests/__Snapshots__/TextDiffSnapshotTests/`.
+- AppKit snapshot tests live in `Tests/TextDiffTests/NSTextDiffSnapshotTests.swift`.
+- Baselines are stored under `Tests/TextDiffTests/__Snapshots__/TextDiffSnapshotTests/` and `Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/`.
 - The suite uses `@Suite(.snapshots(record: .missing))` to record only missing baselines.
 
 Run all tests:
@@ -119,7 +144,7 @@ swift test 2>&1 | xcsift --quiet
 
 Update baselines intentionally:
 
-1. Temporarily switch the suite trait in `Tests/TextDiffTests/TextDiffSnapshotTests.swift` from `.missing` to `.all`.
+1. Temporarily switch the suite trait in snapshot suites (for example, `Tests/TextDiffTests/TextDiffSnapshotTests.swift` and `Tests/TextDiffTests/NSTextDiffSnapshotTests.swift`) from `.missing` to `.all`.
 2. Run `swift test 2>&1 | xcsift --quiet` once to rewrite baselines.
 3. Switch the suite trait back to `.missing`.
 4. Review snapshot image diffs in your PR before merging.
diff --git a/Sources/TextDiff/AppKit/DiffCanvasView.swift b/Sources/TextDiff/AppKit/DiffCanvasView.swift
deleted file mode 100644
index 8793172..0000000
--- a/Sources/TextDiff/AppKit/DiffCanvasView.swift
+++ /dev/null
@@ -1,104 +0,0 @@
-import AppKit
-import Foundation
-
-final class DiffCanvasView: NSView {
-    private var segments: [DiffSegment] = []
-    private var style: TextDiffStyle = .default
-
-    private var cachedWidth: CGFloat = -1
-    private var cachedLayout: DiffLayout?
-
-    override var isFlipped: Bool {
-        true
-    }
-
-    override var intrinsicContentSize: NSSize {
-        let layout = layoutForCurrentWidth()
-        return NSSize(width: NSView.noIntrinsicMetric, height: ceil(layout.contentSize.height))
-    }
-
-    override func setFrameSize(_ newSize: NSSize) {
-        let previousWidth = frame.width
-        super.setFrameSize(newSize)
-        if abs(previousWidth - newSize.width) > 0.5 {
-            invalidateCachedLayout()
-        }
-    }
-
-    override func draw(_ dirtyRect: NSRect) {
-        super.draw(dirtyRect)
-
-        let layout = layoutForCurrentWidth()
-        for run in layout.runs {
-            if let chipRect = run.chipRect {
-                drawChip(
-                    chipRect: chipRect,
-                    fillColor: run.chipFillColor,
-                    strokeColor: run.chipStrokeColor,
-                    cornerRadius: run.chipCornerRadius
-                )
-            }
-
-            run.attributedText.draw(in: run.textRect)
-        }
-    }
-
-    func update(segments: [DiffSegment], style: TextDiffStyle) {
-        self.segments = segments
-        self.style = style
-        invalidateCachedLayout()
-    }
-
-    private func drawChip(
-        chipRect: CGRect,
-        fillColor: NSColor?,
-        strokeColor: NSColor?,
-        cornerRadius: CGFloat
-    ) {
-        guard chipRect.width > 0, chipRect.height > 0 else {
-            return
-        }
-
-        let fillPath = NSBezierPath(roundedRect: chipRect, xRadius: cornerRadius, yRadius: cornerRadius)
-        fillColor?.setFill()
-        fillPath.fill()
-
-        let strokeRect = chipRect.insetBy(dx: 0.5, dy: 0.5)
-        guard strokeRect.width > 0, strokeRect.height > 0 else {
-            return
-        }
-
-        let strokePath = NSBezierPath(roundedRect: strokeRect, xRadius: cornerRadius, yRadius: cornerRadius)
-        strokeColor?.setStroke()
-        strokePath.lineWidth = 1
-        strokePath.stroke()
-    }
-
-    private func layoutForCurrentWidth() -> DiffLayout {
-        let width = max(bounds.width, 1)
-        if let cachedLayout, abs(cachedWidth - width) <= 0.5 {
-            return cachedLayout
-        }
-
-        let verticalInset = DiffTextLayoutMetrics.verticalTextInset(for: style)
-        let contentInsets = NSEdgeInsets(top: verticalInset, left: 0, bottom: verticalInset, right: 0)
-        let availableWidth = max(1, width - contentInsets.left - contentInsets.right)
-        let layout = DiffTokenLayouter.layout(
-            segments: segments,
-            style: style,
-            availableWidth: availableWidth,
-            contentInsets: contentInsets
-        )
-
-        cachedWidth = width
-        cachedLayout = layout
-        return layout
-    }
-
-    private func invalidateCachedLayout() {
-        cachedLayout = nil
-        cachedWidth = -1
-        needsDisplay = true
-        invalidateIntrinsicContentSize()
-    }
-}
diff --git a/Sources/TextDiff/AppKit/DiffTextLayoutMetrics.swift b/Sources/TextDiff/AppKit/DiffTextLayoutMetrics.swift
new file mode 100644
index 0000000..b73b532
--- /dev/null
+++ b/Sources/TextDiff/AppKit/DiffTextLayoutMetrics.swift
@@ -0,0 +1,13 @@
+import AppKit
+
+enum DiffTextLayoutMetrics {
+    static func verticalTextInset(for style: TextDiffStyle) -> CGFloat {
+        ceil(max(2, style.chipInsets.top + 2, style.chipInsets.bottom + 2))
+    }
+
+    static func lineHeight(for style: TextDiffStyle) -> CGFloat {
+        let textHeight = ceil(style.font.ascender - style.font.descender + style.font.leading)
+        let chipHeight = textHeight + style.chipInsets.top + style.chipInsets.bottom
+        return ceil(chipHeight + max(0, style.lineSpacing))
+    }
+}
diff --git a/Sources/TextDiff/AppKit/DiffTextViewRepresentable.swift b/Sources/TextDiff/AppKit/DiffTextViewRepresentable.swift
index d790a85..73d59f0 100644
--- a/Sources/TextDiff/AppKit/DiffTextViewRepresentable.swift
+++ b/Sources/TextDiff/AppKit/DiffTextViewRepresentable.swift
@@ -1,31 +1,30 @@
 import AppKit
 import SwiftUI
 
-enum DiffTextLayoutMetrics {
-    static func verticalTextInset(for style: TextDiffStyle) -> CGFloat {
-        ceil(max(2, style.chipInsets.top + 2, style.chipInsets.bottom + 2))
-    }
-
-    static func lineHeight(for style: TextDiffStyle) -> CGFloat {
-        let textHeight = ceil(style.font.ascender - style.font.descender + style.font.leading)
-        let chipHeight = textHeight + style.chipInsets.top + style.chipInsets.bottom
-        return ceil(chipHeight + max(0, style.lineSpacing))
-    }
-}
-
 struct DiffTextViewRepresentable: NSViewRepresentable {
-    let segments: [DiffSegment]
+    let original: String
+    let updated: String
     let style: TextDiffStyle
+    let mode: TextDiffComparisonMode
 
-    func makeNSView(context: Context) -> DiffCanvasView {
-        let view = DiffCanvasView()
+    func makeNSView(context: Context) -> NSTextDiffView {
+        let view = NSTextDiffView(
+            original: original,
+            updated: updated,
+            style: style,
+            mode: mode
+        )
         view.setContentCompressionResistancePriority(.required, for: .vertical)
         view.setContentHuggingPriority(.required, for: .vertical)
-        view.update(segments: segments, style: style)
         return view
     }
 
-    func updateNSView(_ view: DiffCanvasView, context: Context) {
-        view.update(segments: segments, style: style)
+    func updateNSView(_ view: NSTextDiffView, context: Context) {
+        view.setContent(
+            original: original,
+            updated: updated,
+            style: style,
+            mode: mode
+        )
     }
 }
diff --git a/Sources/TextDiff/AppKit/NSTextDiffView.swift b/Sources/TextDiff/AppKit/NSTextDiffView.swift
new file mode 100644
index 0000000..00920a3
--- /dev/null
+++ b/Sources/TextDiff/AppKit/NSTextDiffView.swift
@@ -0,0 +1,254 @@
+import AppKit
+import Foundation
+
+/// An AppKit view that renders a merged visual diff between two strings.
+public final class NSTextDiffView: NSView {
+    typealias DiffProvider = (String, String, TextDiffComparisonMode) -> [DiffSegment]
+
+    /// The source text before edits.
+    /// Setting this value updates rendered diff output when content changes.
+    public var original: String {
+        didSet {
+            guard !isBatchUpdating else {
+                return
+            }
+            _ = updateSegmentsIfNeeded()
+        }
+    }
+
+    /// The source text after edits.
+    /// Setting this value updates rendered diff output when content changes.
+    public var updated: String {
+        didSet {
+            guard !isBatchUpdating else {
+                return
+            }
+            _ = updateSegmentsIfNeeded()
+        }
+    }
+
+    /// Visual style used to render additions, deletions, and unchanged text.
+    /// Setting this value redraws the view without recomputing diff segments.
+    public var style: TextDiffStyle {
+        didSet {
+            guard !isBatchUpdating else {
+                pendingStyleInvalidation = true
+                return
+            }
+            invalidateCachedLayout()
+        }
+    }
+
+    /// Comparison mode that controls token-level or character-refined output.
+    /// Setting this value updates rendered diff output when mode changes.
+    public var mode: TextDiffComparisonMode {
+        didSet {
+            guard !isBatchUpdating else {
+                return
+            }
+            _ = updateSegmentsIfNeeded()
+        }
+    }
+
+    private var segments: [DiffSegment]
+    private let diffProvider: DiffProvider
+
+    private var lastOriginal: String
+    private var lastUpdated: String
+    private var lastModeKey: Int
+    private var isBatchUpdating = false
+    private var pendingStyleInvalidation = false
+
+    private var cachedWidth: CGFloat = -1
+    private var cachedLayout: DiffLayout?
+
+    override public var isFlipped: Bool {
+        true
+    }
+
+    override public var intrinsicContentSize: NSSize {
+        let layout = layoutForCurrentWidth()
+        return NSSize(width: NSView.noIntrinsicMetric, height: ceil(layout.contentSize.height))
+    }
+
+    /// Creates a text diff view for two versions of content.
+    ///
+    /// - Parameters:
+    ///   - original: The source text before edits.
+    ///   - updated: The source text after edits.
+    ///   - style: Visual style used to render additions, deletions, and unchanged text.
+    ///   - mode: Comparison mode that controls token-level or character-refined output.
+    public init(
+        original: String,
+        updated: String,
+        style: TextDiffStyle = .default,
+        mode: TextDiffComparisonMode = .token
+    ) {
+        self.original = original
+        self.updated = updated
+        self.style = style
+        self.mode = mode
+        self.diffProvider = { original, updated, mode in
+            TextDiffEngine.diff(original: original, updated: updated, mode: mode)
+        }
+        self.lastOriginal = original
+        self.lastUpdated = updated
+        self.lastModeKey = Self.modeKey(for: mode)
+        self.segments = self.diffProvider(original, updated, mode)
+        super.init(frame: .zero)
+    }
+
+    #if TESTING
+    init(
+        original: String,
+        updated: String,
+        style: TextDiffStyle = .default,
+        mode: TextDiffComparisonMode = .token,
+        diffProvider: @escaping DiffProvider
+    ) {
+        self.original = original
+        self.updated = updated
+        self.style = style
+        self.mode = mode
+        self.diffProvider = diffProvider
+        self.lastOriginal = original
+        self.lastUpdated = updated
+        self.lastModeKey = Self.modeKey(for: mode)
+        self.segments = diffProvider(original, updated, mode)
+        super.init(frame: .zero)
+    }
+    #endif
+
+    @available(*, unavailable, message: "Use init(original:updated:style:mode:)")
+    required init?(coder: NSCoder) {
+        fatalError("Use init(original:updated:style:mode:)")
+    }
+
+    override public func setFrameSize(_ newSize: NSSize) {
+        let previousWidth = frame.width
+        super.setFrameSize(newSize)
+        if abs(previousWidth - newSize.width) > 0.5 {
+            invalidateCachedLayout()
+        }
+    }
+
+    override public func draw(_ dirtyRect: NSRect) {
+        super.draw(dirtyRect)
+
+        let layout = layoutForCurrentWidth()
+        for run in layout.runs {
+            if let chipRect = run.chipRect {
+                drawChip(
+                    chipRect: chipRect,
+                    fillColor: run.chipFillColor,
+                    strokeColor: run.chipStrokeColor,
+                    cornerRadius: run.chipCornerRadius
+                )
+            }
+
+            run.attributedText.draw(in: run.textRect)
+        }
+    }
+
+    /// Atomically updates view inputs and recomputes diff segments at most once.
+    public func setContent(
+        original: String,
+        updated: String,
+        style: TextDiffStyle,
+        mode: TextDiffComparisonMode
+    ) {
+        isBatchUpdating = true
+        defer {
+            isBatchUpdating = false
+            let needsStyleInvalidation = pendingStyleInvalidation
+            pendingStyleInvalidation = false
+
+            let didRecompute = updateSegmentsIfNeeded()
+            if needsStyleInvalidation, !didRecompute {
+                invalidateCachedLayout()
+            }
+        }
+
+        self.style = style
+        self.mode = mode
+        self.original = original
+        self.updated = updated
+    }
+
+    @discardableResult
+    private func updateSegmentsIfNeeded() -> Bool {
+        let newModeKey = Self.modeKey(for: mode)
+        guard original != lastOriginal || updated != lastUpdated || newModeKey != lastModeKey else {
+            return false
+        }
+
+        lastOriginal = original
+        lastUpdated = updated
+        lastModeKey = newModeKey
+        segments = diffProvider(original, updated, mode)
+        invalidateCachedLayout()
+        return true
+    }
+
+    private func layoutForCurrentWidth() -> DiffLayout {
+        let width = max(bounds.width, 1)
+        if let cachedLayout, abs(cachedWidth - width) <= 0.5 {
+            return cachedLayout
+        }
+
+        let verticalInset = DiffTextLayoutMetrics.verticalTextInset(for: style)
+        let contentInsets = NSEdgeInsets(top: verticalInset, left: 0, bottom: verticalInset, right: 0)
+        let availableWidth = max(1, width - contentInsets.left - contentInsets.right)
+        let layout = DiffTokenLayouter.layout(
+            segments: segments,
+            style: style,
+            availableWidth: availableWidth,
+            contentInsets: contentInsets
+        )
+
+        cachedWidth = width
+        cachedLayout = layout
+        return layout
+    }
+
+    private func invalidateCachedLayout() {
+        cachedLayout = nil
+        cachedWidth = -1
+        needsDisplay = true
+        invalidateIntrinsicContentSize()
+    }
+
+    private func drawChip(
+        chipRect: CGRect,
+        fillColor: NSColor?,
+        strokeColor: NSColor?,
+        cornerRadius: CGFloat
+    ) {
+        guard chipRect.width > 0, chipRect.height > 0 else {
+            return
+        }
+
+        let fillPath = NSBezierPath(roundedRect: chipRect, xRadius: cornerRadius, yRadius: cornerRadius)
+        fillColor?.setFill()
+        fillPath.fill()
+
+        let strokeRect = chipRect.insetBy(dx: 0.5, dy: 0.5)
+        guard strokeRect.width > 0, strokeRect.height > 0 else {
+            return
+        }
+
+        let strokePath = NSBezierPath(roundedRect: strokeRect, xRadius: cornerRadius, yRadius: cornerRadius)
+        strokeColor?.setStroke()
+        strokePath.lineWidth = 1
+        strokePath.stroke()
+    }
+
+    private static func modeKey(for mode: TextDiffComparisonMode) -> Int {
+        switch mode {
+        case .token:
+            return 0
+        case .character:
+            return 1
+        }
+    }
+}
diff --git a/Sources/TextDiff/TextDiffView.swift b/Sources/TextDiff/TextDiffView.swift
index 43e78d5..2548056 100644
--- a/Sources/TextDiff/TextDiffView.swift
+++ b/Sources/TextDiff/TextDiffView.swift
@@ -7,7 +7,6 @@ public struct TextDiffView: View {
     private let updated: String
     private let mode: TextDiffComparisonMode
     private let style: TextDiffStyle
-    @StateObject private var model: TextDiffViewModel
 
     /// Creates a text diff view for two versions of content.
     ///
@@ -26,33 +25,17 @@ public struct TextDiffView: View {
         self.updated = updated
         self.mode = mode
         self.style = style
-        _model = StateObject(
-            wrappedValue: TextDiffViewModel(original: original, updated: updated, mode: mode)
-        )
     }
 
     /// The view body that renders the current diff content.
     public var body: some View {
-        DiffTextViewRepresentable(segments: model.segments, style: style)
+        DiffTextViewRepresentable(
+            original: original,
+            updated: updated,
+            style: style,
+            mode: mode
+        )
             .accessibilityLabel("Text diff")
-            .onChange(of: original) { _, _ in
-                model.updateIfNeeded(original: original, updated: updated, mode: mode)
-            }
-            .onChange(of: updated) { _, _ in
-                model.updateIfNeeded(original: original, updated: updated, mode: mode)
-            }
-            .onChange(of: modeKey) { _, _ in
-                model.updateIfNeeded(original: original, updated: updated, mode: mode)
-            }
-    }
-
-    private var modeKey: Int {
-        switch mode {
-        case .token:
-            return 0
-        case .character:
-            return 1
-        }
     }
 }
 
@@ -65,13 +48,13 @@ public struct TextDiffView: View {
     .frame(width: 500)
 }
 
-#Preview("Custom Style") {
+#Preview("TextDiffView") {
     let style = TextDiffStyle(
-        additionFillColor: NSColor.systemGreen.withAlphaComponent(0.28),
-        additionStrokeColor: NSColor.systemGreen.withAlphaComponent(0.75),
+        additionFillColor: .systemGreen.withAlphaComponent(0.28),
+        additionStrokeColor: .systemGreen.withAlphaComponent(0.75),
         additionTextColorOverride: .labelColor,
-        deletionFillColor: NSColor.systemRed.withAlphaComponent(0.24),
-        deletionStrokeColor: NSColor.systemRed.withAlphaComponent(0.75),
+        deletionFillColor: .systemRed.withAlphaComponent(0.24),
+        deletionStrokeColor: .systemRed.withAlphaComponent(0.75),
         deletionTextColorOverride: .secondaryLabelColor,
         unchangedTextColor: .labelColor,
         font: .systemFont(ofSize: 16, weight: .regular),
diff --git a/Tests/TextDiffTests/NSTextDiffSnapshotTests.swift b/Tests/TextDiffTests/NSTextDiffSnapshotTests.swift
new file mode 100644
index 0000000..7af8152
--- /dev/null
+++ b/Tests/TextDiffTests/NSTextDiffSnapshotTests.swift
@@ -0,0 +1,66 @@
+import AppKit
+import SnapshotTesting
+import Testing
+import TextDiff
+
+@Suite(.snapshots(record: .missing))
+@MainActor
+struct NSTextDiffSnapshotTests {
+    @Test
+    func token_basic_replacement() {
+        assertNSTextDiffSnapshot(
+            original: "Apply old value in this sentence.",
+            updated: "Apply new value in this sentence.",
+            mode: .token,
+            size: CGSize(width: 500, height: 120)
+        )
+    }
+
+    @Test
+    func character_suffix_refinement() {
+        assertNSTextDiffSnapshot(
+            original: "Add a diff",
+            updated: "Added a diff",
+            mode: .character,
+            size: CGSize(width: 320, height: 110)
+        )
+    }
+
+    @Test
+    func punctuation_replacement() {
+        assertNSTextDiffSnapshot(
+            original: "Wait!",
+            updated: "Wait.",
+            mode: .token,
+            size: CGSize(width: 320, height: 100)
+        )
+    }
+
+    @Test
+    func multiline_insertion_wrap() {
+        assertNSTextDiffSnapshot(
+            original: "line1\nline2",
+            updated: "line1\nlineX\nline2",
+            mode: .token,
+            size: CGSize(width: 300, height: 150)
+        )
+    }
+
+    @Test
+    func custom_style_spacing_strikethrough() {
+        var style = TextDiffStyle.default
+        style.deletionStrikethrough = true
+        style.interChipSpacing = 1
+
+        assertNSTextDiffSnapshot(
+            original: sampleOriginalSentence,
+            updated: sampleUpdatedSentence,
+            mode: .character,
+            style: style,
+            size: CGSize(width: 300, height: 180)
+        )
+    }
+
+    private let sampleOriginalSentence = "A quick brown fox jumps over a lazy dog."
+    private let sampleUpdatedSentence = "A quick fox hops over the lazy dog!"
+}
diff --git a/Tests/TextDiffTests/NSTextDiffViewTests.swift b/Tests/TextDiffTests/NSTextDiffViewTests.swift
new file mode 100644
index 0000000..85968c3
--- /dev/null
+++ b/Tests/TextDiffTests/NSTextDiffViewTests.swift
@@ -0,0 +1,143 @@
+import Testing
+@testable import TextDiff
+
+@Test
+@MainActor
+func nsTextDiffViewInitComputesExactlyOnce() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    #expect(callCount == 1)
+    #expect(view.intrinsicContentSize.height > 0)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewRecomputesWhenOriginalChanges() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    view.original = "old-2"
+
+    #expect(callCount == 2)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewRecomputesWhenUpdatedChanges() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    view.updated = "new-2"
+
+    #expect(callCount == 2)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewRecomputesWhenModeChanges() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    view.mode = .character
+
+    #expect(callCount == 2)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewStyleChangeDoesNotRecomputeDiff() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    var style = TextDiffStyle.default
+    style.deletionStrikethrough = true
+    view.style = style
+
+    #expect(callCount == 1)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewSetContentBatchesRecompute() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    var style = TextDiffStyle.default
+    style.deletionStrikethrough = true
+    view.setContent(
+        original: "old-2",
+        updated: "new-2",
+        style: style,
+        mode: .character
+    )
+
+    #expect(callCount == 2)
+}
+
+@Test
+@MainActor
+func nsTextDiffViewSetContentStyleOnlyDoesNotRecomputeDiff() {
+    var callCount = 0
+    let view = NSTextDiffView(
+        original: "old",
+        updated: "new",
+        mode: .token
+    ) { _, _, _ in
+        callCount += 1
+        return [DiffSegment(kind: .equal, tokenKind: .word, text: "\(callCount)")]
+    }
+
+    var style = TextDiffStyle.default
+    style.deletionStrikethrough = true
+    view.setContent(
+        original: "old",
+        updated: "new",
+        style: style,
+        mode: .token
+    )
+
+    #expect(callCount == 1)
+}
diff --git a/Tests/TextDiffTests/SnapshotTestSupport.swift b/Tests/TextDiffTests/SnapshotTestSupport.swift
index c8be695..795e220 100644
--- a/Tests/TextDiffTests/SnapshotTestSupport.swift
+++ b/Tests/TextDiffTests/SnapshotTestSupport.swift
@@ -51,6 +51,54 @@ func assertTextDiffSnapshot(
     )
 }
 
+@MainActor
+func assertNSTextDiffSnapshot(
+    original: String,
+    updated: String,
+    mode: TextDiffComparisonMode = .token,
+    style: TextDiffStyle = .default,
+    size: CGSize,
+    named name: String? = nil,
+    fileID: StaticString = #fileID,
+    filePath: StaticString = #filePath,
+    testName: String = #function,
+    line: UInt = #line,
+    column: UInt = #column
+) {
+    let diffView = NSTextDiffView(
+        original: original,
+        updated: updated,
+        style: style,
+        mode: mode
+    )
+
+    let container = NSView(frame: CGRect(origin: .zero, size: size))
+    container.wantsLayer = true
+    container.layer?.backgroundColor = NSColor.white.cgColor
+    container.appearance = NSAppearance(named: .aqua)
+
+    diffView.frame = container.bounds
+    diffView.autoresizingMask = [.width, .height]
+    container.addSubview(diffView)
+    container.layoutSubtreeIfNeeded()
+
+    let snapshotImage = renderSnapshotImage1x(view: container, size: size)
+
+    assertSnapshot(
+        of: snapshotImage,
+        as: .image(
+            precision: snapshotPrecision,
+            perceptualPrecision: snapshotPerceptualPrecision
+        ),
+        named: name,
+        fileID: fileID,
+        file: filePath,
+        testName: testName,
+        line: line,
+        column: column
+    )
+}
+
 @MainActor
 private func renderSnapshotImage1x(view: NSView, size: CGSize) -> NSImage {
     let rep = NSBitmapImageRep(
diff --git a/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/character_suffix_refinement.1.png b/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/character_suffix_refinement.1.png
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diff --git a/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/multiline_insertion_wrap.1.png b/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/multiline_insertion_wrap.1.png
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index 0000000..3006387
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diff --git a/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/punctuation_replacement.1.png b/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/punctuation_replacement.1.png
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diff --git a/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/token_basic_replacement.1.png b/Tests/TextDiffTests/__Snapshots__/NSTextDiffSnapshotTests/token_basic_replacement.1.png
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