diff --git a/Sources/OpenSwiftUICore/Data/DynamicProperty/DynamicPropertyBuffer.swift b/Sources/OpenSwiftUICore/Data/DynamicProperty/DynamicPropertyBuffer.swift
index c6f1379cb..1b94495be 100644
--- a/Sources/OpenSwiftUICore/Data/DynamicProperty/DynamicPropertyBuffer.swift
+++ b/Sources/OpenSwiftUICore/Data/DynamicProperty/DynamicPropertyBuffer.swift
@@ -4,7 +4,8 @@
 //
 //  Audited for iOS 15.5
 //  Status: Complete
-//  ID: 68550FF604D39F05971FE35A26EE75B0
+//  ID: 68550FF604D39F05971FE35A26EE75B0 (SwiftUI)
+//  ID: F3A89CF4357225EF49A7DD673FDFEE02 (SwiftUICore)
 
 import OpenGraphShims
 
diff --git a/Sources/OpenSwiftUICore/Data/DynamicProperty/UnsafeHeterogeneousBuffer.swift b/Sources/OpenSwiftUICore/Data/DynamicProperty/UnsafeHeterogeneousBuffer.swift
new file mode 100644
index 000000000..cc43c6fd8
--- /dev/null
+++ b/Sources/OpenSwiftUICore/Data/DynamicProperty/UnsafeHeterogeneousBuffer.swift
@@ -0,0 +1,218 @@
+//
+//  UnsafeHeterogeneousBuffer.swift
+//  OpenSwiftUICore
+//
+//  Audited for iOS 18.0
+//  Status: Complete
+//  ID: 568350FE259575B5E1AAA52AD722AAAC (SwiftUICore)
+
+package struct UnsafeHeterogeneousBuffer: Collection {
+    var buf: UnsafeMutableRawPointer!
+    var available: Int32
+    var _count: Int32
+    
+    package typealias VTable = _UnsafeHeterogeneousBuffer_VTable
+    package typealias Element = _UnsafeHeterogeneousBuffer_Element
+    
+    package struct Index: Equatable, Comparable {
+        var index: Int32
+        var offset: Int32
+        
+        package static func < (lhs: Index, rhs: Index) -> Bool {
+            lhs.index < rhs.index
+        }
+        
+        package static func == (a: Index, b: Index) -> Bool {
+            a.index == b.index && a.offset == b.offset
+        }
+    }
+    
+    package struct Item {
+        let vtable: _UnsafeHeterogeneousBuffer_VTable.Type
+        let size: Int32
+        var flags: UInt32
+    }
+    
+    package var count: Int { Int(_count) }
+    package var isEmpty: Bool { _count == 0 }
+    
+    package var startIndex: Index {
+        Index(index: 0, offset: 0)
+    }
+    package var endIndex: Index {
+        Index(index: _count, offset: 0)
+    }
+    
+    package init() {
+        buf = nil
+        available = 0
+        _count = 0
+    }
+    
+    private mutating func allocate(_ bytes: Int) -> UnsafeMutableRawPointer {
+        var count = _count
+        var offset = 0
+        var size = 0
+        while count != 0 {
+            let itemSize = buf
+                .advanced(by: offset)
+                .assumingMemoryBound(to: Item.self)
+                .pointee
+                .size
+            offset &+= Int(itemSize)
+            count &-= 1
+            offset = count == 0 ? 0 : offset
+            size &+= Int(itemSize)
+        }
+        // Grow buffer if needed
+        if Int(available) < bytes {
+            growBuffer(by: bytes, capacity: size + Int(available))
+        }
+        let ptr = buf.advanced(by: size)
+        available = available - Int32(bytes)
+        return ptr
+    }
+    
+    private mutating func growBuffer(by size: Int, capacity: Int) {
+        let expectedSize = size + capacity
+        var allocSize = Swift.max(capacity &* 2, 64)
+        while allocSize < expectedSize {
+            allocSize &*= 2
+        }
+        let allocatedBuffer = UnsafeMutableRawPointer.allocate(
+            byteCount: allocSize,
+            alignment: .zero
+        )
+        if let buf {
+            var count = _count
+            if count != 0 {
+                var itemSize: Int32 = 0
+                var oldBuffer = buf
+                var newBuffer = allocatedBuffer
+                repeat {
+                    count &-= 1
+                    let newItemPointer = newBuffer.assumingMemoryBound(to: Item.self)
+                    let oldItemPointer = oldBuffer.assumingMemoryBound(to: Item.self)
+                    
+                    if count == 0 {
+                        itemSize = 0
+                    } else {
+                        itemSize &+= oldItemPointer.pointee.size
+                    }
+                    newItemPointer.initialize(to: oldItemPointer.pointee)                    
+                    oldItemPointer.pointee.vtable.moveInitialize(
+                        elt: .init(item: newItemPointer),
+                        from: .init(item: oldItemPointer)
+                    )
+                    let size = Int(oldItemPointer.pointee.size)
+                    oldBuffer += size
+                    newBuffer += size
+                } while count != 0 || itemSize != 0
+                
+            }
+            buf.deallocate()
+        }
+        buf = allocatedBuffer
+        available += Int32(allocSize - capacity)
+    }
+    
+    package func destroy() {
+        defer { buf?.deallocate() }
+        guard _count != 0 else {
+            return
+        }
+        var count = _count
+        var offset = 0
+        while count != 0 {
+            let itemPointer = buf
+                .advanced(by: offset)
+                .assumingMemoryBound(to: Item.self)
+            itemPointer.pointee.vtable.deinitialize(elt: .init(item: itemPointer))
+            offset &+= Int(itemPointer.pointee.size)
+            count &-= 1
+        }
+    }
+    
+    package func formIndex(after index: inout Index) {
+        index = self.index(after: index)
+    }
+    
+    package func index(after index: Index) -> Index {
+        let item = self[index].item.pointee
+        let newIndex = index.index &+ 1
+        if newIndex == _count {
+            return Index(index: newIndex, offset: 0)
+        } else {
+            let newOffset = index.offset &+ item.size
+            return Index(index: newIndex, offset: newOffset)
+        }
+    }
+    
+    package subscript(index: Index) -> Element {
+        .init(item: buf
+            .advanced(by: Int(index.offset))
+            .assumingMemoryBound(to: Item.self)
+        )
+    }
+    
+    @discardableResult
+    package mutating func append<T>(_ value: T, vtable: VTable.Type) -> Index {
+        let bytes = MemoryLayout<T>.size + MemoryLayout<UnsafeHeterogeneousBuffer.Item>.size
+        let pointer = allocate(bytes)
+        let element = _UnsafeHeterogeneousBuffer_Element(item: pointer.assumingMemoryBound(to: Item.self))
+        element.item.initialize(to: Item(vtable: vtable, size: Int32(bytes), flags: 0))
+        element.body(as: T.self).initialize(to: value)
+        let index = Index(index: _count, offset: Int32(pointer - buf))
+        _count += 1
+        return index
+    }
+}
+
+@_spi(ForOpenSwiftUIOnly)
+public struct _UnsafeHeterogeneousBuffer_Element {
+    var item: UnsafeMutablePointer<UnsafeHeterogeneousBuffer.Item>
+    
+    package func hasType<T>(_ type: T.Type) -> Bool {
+        item.pointee.vtable.hasType(type)
+    }
+    
+    package func vtable<T>(as type: T.Type) -> T.Type where T: _UnsafeHeterogeneousBuffer_VTable {
+        address.assumingMemoryBound(to: Swift.type(of: type)).pointee
+    }
+    
+    package func body<T>(as type: T.Type) -> UnsafeMutablePointer<T> {
+        UnsafeMutableRawPointer(item.advanced(by: 1)).assumingMemoryBound(to: type)
+    }
+    
+    package var flags: UInt32 {
+        get { item.pointee.flags }
+        nonmutating set { item.pointee.flags = newValue }
+    }
+    
+    package var address: UnsafeRawPointer {
+        UnsafeRawPointer(item)
+    }
+}
+
+@_spi(ForOpenSwiftUIOnly)
+@available(*, unavailable)
+extension _UnsafeHeterogeneousBuffer_Element: Sendable {}
+
+@_spi(ForOpenSwiftUIOnly)
+open class _UnsafeHeterogeneousBuffer_VTable {
+    open class func hasType<T>(_ type: T.Type) -> Bool {
+        false
+    }
+    
+    open class func moveInitialize(elt: _UnsafeHeterogeneousBuffer_Element, from: _UnsafeHeterogeneousBuffer_Element) {
+        preconditionFailure("")
+    }
+    
+    open class func deinitialize(elt: _UnsafeHeterogeneousBuffer_Element) {
+        preconditionFailure("")
+    }
+}
+
+@_spi(ForOpenSwiftUIOnly)
+@available(*, unavailable)
+extension _UnsafeHeterogeneousBuffer_VTable: Sendable {}
diff --git a/Tests/OpenSwiftUICoreTests/Data/DynamicProperty/UnsafeHeterogeneousBufferTests.swift b/Tests/OpenSwiftUICoreTests/Data/DynamicProperty/UnsafeHeterogeneousBufferTests.swift
new file mode 100644
index 000000000..0faea46c0
--- /dev/null
+++ b/Tests/OpenSwiftUICoreTests/Data/DynamicProperty/UnsafeHeterogeneousBufferTests.swift
@@ -0,0 +1,94 @@
+//
+//  UnsafeHeterogeneousBufferTests.swift
+//  OpenSwiftUICoreTests
+
+@_spi(ForOpenSwiftUIOnly) import OpenSwiftUICore
+@testable import OpenSwiftUICore
+import Testing
+
+struct UnsafeHeterogeneousBufferTests {
+    private final class VTable<Value>: _UnsafeHeterogeneousBuffer_VTable {
+        override class func hasType<T>(_ type: T.Type) -> Bool {
+            Value.self == T.self
+        }
+        
+        override class func moveInitialize(elt: _UnsafeHeterogeneousBuffer_Element, from: _UnsafeHeterogeneousBuffer_Element) {
+            let dest = elt.body(as: Value.self)
+            let source = from.body(as: Value.self)
+            dest.initialize(to: source.move())
+        }
+        
+        override class func deinitialize(elt: _UnsafeHeterogeneousBuffer_Element) {
+            elt.body(as: Value.self).deinitialize(count: 1)
+        }
+    }
+    
+    @Test
+    func structBuffer() {
+        var buffer = UnsafeHeterogeneousBuffer()
+        defer { buffer.destroy() }
+        #expect(buffer.isEmpty == true)
+        
+        do {
+            let index = buffer.append(UInt32(1), vtable: VTable<Int32>.self)
+            #expect(buffer.isEmpty == false)
+            #expect(index == buffer.index(atOffset: 0))
+            #expect(index.index == 0)
+            #expect(index.offset == 0)
+            #expect(buffer.available == 44)
+            #expect(buffer.count == 1)
+            let element = buffer[index]
+            #expect(element.body(as: UInt32.self).pointee == 1)
+        }
+        
+        do {
+            let index = buffer.append(Int(-1), vtable: VTable<Int>.self)
+            #expect(buffer.isEmpty == false)
+            #expect(index == buffer.index(atOffset: 1))
+            #expect(index.index == 1)
+            #expect(index.offset == 16 + 4)
+            #expect(buffer.available == 20)
+            #expect(buffer.count == 2)
+            let element = buffer[index]
+            #expect(element.body(as: Int.self).pointee == -1)
+        }
+        
+        do {
+            let index = buffer.append(Double.infinity, vtable: VTable<Double>.self)
+            #expect(buffer.isEmpty == false)
+            #expect(index == buffer.index(atOffset: 2))
+            #expect(index.index == 2)
+            #expect(index.offset == 16 + 4 + 16 + 8)
+            #expect(buffer.available == 60)
+            #expect(buffer.count == 3)
+            let element = buffer[index]
+            #expect(element.body(as: Double.self).pointee == Double.infinity)
+        }
+    }
+    
+    @Test
+    func classBuffer() async throws {
+        final class DeinitBox {
+            let deinitBlock: () -> Void
+            
+            init(deinitBlock: @escaping () -> Void) {
+                self.deinitBlock = deinitBlock
+            }
+            
+            deinit {
+                deinitBlock()
+            }
+        }
+        
+        
+        await confirmation { confirm in
+            var buffer = UnsafeHeterogeneousBuffer()
+            defer { buffer.destroy() }
+            #expect(buffer.isEmpty == true)
+            let box = DeinitBox { confirm() }
+            let index = buffer.append(box, vtable: VTable<DeinitBox>.self)
+            let element = buffer[index]
+            #expect(element.body(as: DeinitBox.self).pointee === box)
+        }
+    }
+}