new implementation based on the usage of NSTextAttachment to allocate space for the timestamp

ElementX/Sources/Other/Extensions/String.swift

@@ -101,6 +101,25 @@ extension String {
     }
 }
 
+extension String {
+    /// Whether the first character with a strong BiDi direction is right-to-left.
+    /// Mirrors the Unicode BiDi "first strong" rule used by TextKit to resolve
+    /// paragraph direction when `baseWritingDirection` is `.natural`.
+    var firstStrongCharacterIsRTL: Bool {
+        for scalar in unicodeScalars {
+            let value = scalar.value
+            // Strong RTL: Hebrew, Arabic, Syriac, Thaana, NKo, Samaritan, Mandaic,
+            // Arabic Extended, and their presentation forms.
+            let isStrongRTL = (0x0590...0x08FF).contains(value) ||
+                (0xFB1D...0xFDFF).contains(value) ||
+                (0xFE70...0xFEFF).contains(value)
+            if isStrongRTL { return true }
+            if scalar.properties.isAlphabetic { return false }
+        }
+        return false
+    }
+}
+
 extension String {
     /// To be used if the string is actually a URL
     var asSanitizedLink: String {

ElementX/Sources/Other/Pills/MessageText.swift

@@ -55,9 +55,25 @@ final class MessageTextView: UITextView, PillAttachmentViewProviderDelegate, UIG
     }
 }
 
+/// An `NSTextAttachment` that takes up its declared `bounds` but draws nothing — used
+/// as an invisible spacer so a message bubble's text reserves room for the overlaid
+/// timestamp. Without this subclass, an attachment with no image would render TextKit's
+/// default "missing image" glyph.
+private final class TransparentTextAttachment: NSTextAttachment {
+    override func image(forBounds imageBounds: CGRect,
+                        textContainer: NSTextContainer?,
+                        characterIndex charIndex: Int) -> UIImage? {
+        let format = UIGraphicsImageRendererFormat()
+        format.opaque = false
+        let size = CGSize(width: max(imageBounds.width, 1), height: max(imageBounds.height, 1))
+        return UIGraphicsImageRenderer(size: size, format: format).image { _ in }
+    }
+}
+
 struct MessageText: UIViewRepresentable {
     @Environment(\.openURL) private var openURLAction
     @Environment(\.timelineContext) private var viewModel
+    @Environment(\.layoutDirection) private var layoutDirection
     @State private var computedSizes = [Double: CGSize]()
     
     @State var attributedString: AttributedString {
@@ -66,6 +82,50 @@ struct MessageText: UIViewRepresentable {
         }
     }
     
+    /// Reserves an invisible inline area of this size at the very end of the rendered
+    /// text. Used so that the message bubble's natural size accommodates the timestamp
+    /// overlaid on top of the bubble's bottom-trailing corner. TextKit decides whether
+    /// the reserved region fits on the last line (timestamp tucks) or wraps to a new
+    /// line (timestamp drops below the text).
+    var trailingReservedSize: CGSize = .zero
+    
+    private func makeAttributedText() -> NSAttributedString? {
+        guard let baseText = try? NSAttributedString(attributedString, including: \.elementX) else {
+            return nil
+        }
+
+        let combined = NSMutableAttributedString(attributedString: baseText)
+        if trailingReservedSize.width > 0 {
+            let attachment = TransparentTextAttachment()
+            attachment.isAccessibilityElement = false
+            attachment.bounds = CGRect(origin: .zero,
+                                       size: CGSize(width: trailingReservedSize.width,
+                                                    height: max(trailingReservedSize.height, 1)))
+
+            // When the last paragraph's natural text direction doesn't match the layout
+            // direction, the inline attachment would land on the wrong side and overlap the
+            // overlaid timestamp. Force it onto its own line so the bubble just grows taller.
+            if !lastParagraphDirectionMatchesLayout(in: combined) {
+                combined.append(NSAttributedString(string: "\n"))
+            }
+
+            combined.append(NSAttributedString(attachment: attachment))
+        }
+
+        return combined
+    }
+
+    private func lastParagraphDirectionMatchesLayout(in attributedText: NSAttributedString) -> Bool {
+        let string = attributedText.string as NSString
+        guard string.length > 0 else { return true }
+
+        let lastParagraphRange = string.paragraphRange(for: NSRange(location: string.length - 1, length: 0))
+        let lastParagraph = string.substring(with: lastParagraphRange)
+
+        let textIsRTL = lastParagraph.firstStrongCharacterIsRTL
+        return textIsRTL == (layoutDirection == .rightToLeft)
+    }
+    
     func makeUIView(context: Context) -> MessageTextView {
         // Need to use TextKit 1 for mentions
         let textView = MessageTextView(usingTextLayoutManager: false)
@@ -97,7 +157,7 @@ struct MessageText: UIViewRepresentable {
         textView.textContainer.lineFragmentPadding = 0
         textView.layoutManager.usesFontLeading = false
         textView.backgroundColor = .clear
-        if let attributedText = try? NSAttributedString(attributedString, including: \.elementX) {
+        if let attributedText = makeAttributedText() {
             textView.attributedText = attributedText
         }
         textView.delegate = context.coordinator
@@ -105,10 +165,11 @@ struct MessageText: UIViewRepresentable {
     }
     
     func updateUIView(_ uiView: MessageTextView, context: Context) {
-        if let newAttributedText = try? NSAttributedString(attributedString, including: \.elementX),
+        if let newAttributedText = makeAttributedText(),
            uiView.attributedText != newAttributedText {
             uiView.flushPills()
             uiView.attributedText = newAttributedText
+            computedSizes.removeAll()
         }
         context.coordinator.openURLAction = openURLAction
     }

ElementX/Sources/Services/Timeline/TimelineItems/EventBasedTimelineItemProtocol.swift

@@ -64,18 +64,27 @@ extension EventBasedTimelineItemProtocol {
         }
     }
 
-    func additionalWhitespaces() -> Int {
-        var whiteSpaces = 1
-        localizedSendInfo.forEach { _ in
-            whiteSpaces += 1
-        }
-
-        // To account for the extra spacing created by the status icon
+    /// The inline area to reserve at the trailing edge of the message text so the
+    /// bubble's natural size accommodates the timestamp (which is overlaid on the
+    /// bubble's bottom-trailing corner). Text wraps around this area: if it fits on
+    /// the last line, the timestamp tucks inline; otherwise it sits on a new line.
+    /// Sized using the same dynamic-type-aware font as the rendered timestamp.
+    var trailingReservedSize: CGSize {
+        let textStyle: UIFont.TextStyle = .caption1 // matches compound.bodyXS
+        let font = UIFont.preferredFont(forTextStyle: textStyle)
+        let textSize = (localizedSendInfo as NSString).size(withAttributes: [.font: font])
+        var width = textSize.width
+        var height = textSize.height
         if hasStatusIcon {
-            whiteSpaces += 3
+            // CompoundIcon at .xSmall is 16pt at the base size; scale with the same UIFontMetrics
+            // as the icon's `relativeTo: .compound.bodyXS` modifier, plus the 4pt HStack spacing.
+            let iconSize = UIFontMetrics(forTextStyle: textStyle).scaledValue(for: 16)
+            width += iconSize + 4
+            height = max(height, iconSize)
         }
-
-        return whiteSpaces
+        // Small visual gap between the text content and the overlaid timestamp.
+        width += 4
+        return CGSize(width: ceil(width), height: ceil(height))
     }
 
     /// contains the timestamp and an optional edited localised prefix