updating transcript row changes'

NucleicRemote/NucleicRemote/Views/TranscriptRow.swift

@@ -111,15 +111,7 @@ struct MessageBubble: View {
 
     var body: some View {
         if role == .user {
-            HStack {
+            UserMessageBubble(text: text)
-                Spacer(minLength: 48)
-                MarkdownText(markdown: text)
-                    .textSelection(.enabled)
-                    .padding(.horizontal, 14)
-                    .padding(.vertical, 9)
-                    .background(Palette.accent.opacity(0.15),
-                                in: RoundedRectangle(cornerRadius: 18, style: .continuous))
-            }
         } else {
             MarkdownText(markdown: text)
                 .textSelection(.enabled)
@@ -136,6 +128,93 @@ struct MessageBubble: View {
     }
 }
 
+/// The user's own message: a right-aligned accent bubble that collapses a long message to a
+/// capped height with a "Show more"/"Show less" toggle — the phone echo of the Mac's
+/// `UserMessageBubble`. The Mac clamps a plain `Text` by line count; here the bubble renders
+/// through `MarkdownText` (a stack of per-line/-block `Text`s that `.lineLimit` can't reach), so
+/// we clamp by height instead. A hidden full-height copy of the bubble — laid out at the visible
+/// bubble's width but with no height limit — measures the natural content height, so the toggle
+/// appears only when collapsing actually hides something. The last visible line fades when
+/// collapsed so the cut reads as "more below" rather than a glyph sliced in half.
+private struct UserMessageBubble: View {
+    let text: String
+    @State private var expanded = false
+    @State private var fullHeight: CGFloat = 0
+    /// Collapsed bubbles show at most this much prose (~12 wrapped lines at the base size, matching
+    /// the Mac's 12-line clamp) before a "Show more". A `@ScaledMetric` so it grows with the user's
+    /// text-size setting alongside `MarkdownText`'s own scaled prose size.
+    @ScaledMetric(relativeTo: .body) private var collapsedMaxHeight: CGFloat = 288
+    /// Collapsing only hides something — and the toggle is only meaningful — when the full,
+    /// unconstrained content is taller than the collapsed cap. The +1 absorbs sub-point rounding.
+    private var isTruncated: Bool { fullHeight > collapsedMaxHeight + 1 }
+    private var collapsed: Bool { isTruncated && !expanded }
+
+    var body: some View {
+        VStack(alignment: .trailing, spacing: 4) {
+            HStack {
+                Spacer(minLength: 48)
+                MarkdownText(markdown: text)
+                    .textSelection(.enabled)
+                    .padding(.horizontal, 14)
+                    .padding(.vertical, 9)
+                    // Cap the height whenever collapsed; harmless for a short message (the cap sits
+                    // above its natural height, so nothing clips). `.clipped` cuts the overflow.
+                    .frame(maxHeight: expanded ? nil : collapsedMaxHeight, alignment: .top)
+                    .clipped()
+                    .mask {
+                        if collapsed { collapseFade } else { Color.black }
+                    }
+                    // The bubble fill is added after the mask, so only the prose fades — not the
+                    // accent behind it, which stays a solid rounded rect.
+                    .background(alignment: .top) { heightProbe }
+                    .background(Palette.accent.opacity(0.15),
+                                in: RoundedRectangle(cornerRadius: 18, style: .continuous))
+            }
+            if isTruncated {
+                Button { expanded.toggle() } label: {
+                    Text(expanded ? "Show less" : "Show more")
+                        .font(.caption.weight(.medium))
+                        .foregroundStyle(Palette.accent)
+                }
+                .buttonStyle(.plain)
+                .padding(.trailing, 4)
+            }
+        }
+    }
+
+    /// A hidden copy of the bubble laid out at the visible bubble's width but with no height limit,
+    /// so its measured height is the full content height regardless of the collapse cap. Attached as
+    /// a background so it inherits the visible bubble's width and wraps identically.
+    private var heightProbe: some View {
+        MarkdownText(markdown: text)
+            .padding(.horizontal, 14)
+            .padding(.vertical, 9)
+            .fixedSize(horizontal: false, vertical: true)
+            .background(GeometryReader { geo in
+                Color.clear.preference(key: FullHeightKey.self, value: geo.size.height)
+            })
+            .hidden()
+            .onPreferenceChange(FullHeightKey.self) { fullHeight = $0 }
+    }
+
+    /// Solid for all but the bottom sliver, then fades to clear — so a collapsed bubble's last
+    /// visible line dissolves instead of being clipped mid-glyph.
+    private var collapseFade: some View {
+        LinearGradient(
+            stops: [
+                .init(color: .black, location: 0),
+                .init(color: .black, location: 0.86),
+                .init(color: .clear, location: 1),
+            ],
+            startPoint: .top, endPoint: .bottom)
+    }
+}
+
+private struct FullHeightKey: PreferenceKey {
+    static let defaultValue: CGFloat = 0
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) { value = max(value, nextValue()) }
+}
+
 /// The agent's reasoning, set apart from its prose by a quiet left rule and a `sparkles` glyph,
 /// italic and muted — the phone echo of the Mac's `thinkingRow`. Renders nothing for an
 /// empty/redacted thinking block (matching the desktop), so a placeholder row never shows.