Eliminate explicitAlignment recursion in message list layout (LUM-800) #24446
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -266,22 +266,21 @@ struct ChatBubble: View, Equatable { | |
| func bubbleChrome<Content: View>(@ViewBuilder _ content: () -> Content) -> some View { | ||
| let isPlainAssistant = !isUser && !message.isError | ||
| if message.isError { | ||
| // ⚠️ No .frame(maxWidth:) in LazyVStack cells — see AGENTS.md. | ||
| // .containerRelativeFrame resolves against the ScrollView for full-width error background. | ||
| content() | ||
| .padding(EdgeInsets(top: VSpacing.md, leading: VSpacing.lg, | ||
| bottom: VSpacing.md, trailing: VSpacing.lg)) | ||
| .containerRelativeFrame(.horizontal) | ||
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There was a problem hiding this comment. 🔴 The error bubble branch in Layout chain showing the mismatchScrollView (width W) → AlignmentBarrierLayout → LazyVStack.padding(.horizontal, VSpacing.xl) → cell proposed (W − 48pt) → HStack → VStack → bubbleChrome → .containerRelativeFrame(.horizontal) resolves to W (not W − 48pt) Prompt for agents
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There was a problem hiding this comment. This is a known tradeoff already documented in the PR's testing checklist. The alternatives were evaluated:
Option 3 is the least-bad choice. The |
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| .background { | ||
| bubbleChromeBackground | ||
| } | ||
| } else if isPlainAssistant { | ||
| // Plain assistant: no chrome padding, no inner frame. | ||
| content() | ||
| .background { | ||
| bubbleChromeBackground | ||
| } | ||
| } else { | ||
| // User messages (non-error): chrome padding, no inner frame. | ||
| content() | ||
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@@ -290,7 +289,6 @@ struct ChatBubble: View, Equatable { | |
| .background { | ||
| bubbleChromeBackground | ||
| } | ||
| } | ||
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ashleeradka marked this conversation as resolved.
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| } | ||
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@@ -341,12 +339,15 @@ struct ChatBubble: View, Equatable { | |
| let _ = os_signpost(.event, log: PerfSignposts.log, name: "chatBubbleBody", | ||
| "id=%{public}s streaming=%d", message.id.uuidString, message.isStreaming ? 1 : 0) | ||
| #endif | ||
| // ⚠️ No .frame(maxWidth:) in LazyVStack cells — see AGENTS.md. | ||
| HStack(spacing: 0) { | ||
| if isUser { Spacer(minLength: 0) } | ||
| // Outer VStack ensures a single resolved subview for the parent | ||
| // LazyVStack, avoiding duplicate .id(message.id) from MessageCellView | ||
| // that caused incorrect width proposals at narrow window sizes (LUM-688). | ||
| // The avatar sits outside the inner .compositingGroup() scope so | ||
| // CAShapeLayer animations (breathing, blink, twitch) are unaffected. | ||
| VStack(alignment: isUser ? .trailing : .leading, spacing: VSpacing.sm) { | ||
| // --- Message content (composited) --- | ||
| VStack(alignment: isUser ? .trailing : .leading, spacing: VSpacing.sm) { | ||
| if !isUser && cachedHasInterleavedContent { | ||
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@@ -425,8 +426,9 @@ struct ChatBubble: View, Equatable { | |
| if isLatestAssistantMessage && !isUser && !hideInlineAvatar { | ||
| inlineAvatar | ||
| } | ||
| } | ||
| if !isUser { Spacer(minLength: 0) } | ||
| } | ||
| .contentShape(Rectangle()) | ||
| .onChange(of: message.contentOrder) { _, _ in recomputeInterleavedContentCache() } | ||
| .onChange(of: message.textSegments) { _, _ in recomputeInterleavedContentCache() } | ||
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🚩 Remaining
.frame(maxWidth:)usages in non-modified filesThe PR removes
.frame(maxWidth:)from LazyVStack cell hierarchies in the modified files, but several unmodified files still use the pattern within the same LazyVStack:ChatBubbleAttachmentContent.swift:144,269,408,ChatLoadingSkeleton.swift:37,45,ChatEmptyStateView.swift:124,154,167,400. If the AGENTS.md rule about no.frame(maxWidth:)in LazyVStack cells is to be enforced consistently, these would need follow-up. However, attachment views with fixed max widths (notalignment:parameter) may produce_FlexFrameLayoutwithout the problematic alignment queries, so the performance impact may vary.Was this helpful? React with 👍 or 👎 to provide feedback.
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These are all outside the scope of this PR and protected by the
AlignmentBarrierLayoutbarrier — alignment queries from the outer.frame(maxWidth:)chain stop at the barrier and never reach the LazyVStack. The remaining sites inChatBubbleAttachmentContent,ChatLoadingSkeleton, andChatEmptyStateViewcan be addressed in a follow-up if spindump shows any residual hits after the barrier is verified.