[LUM-833] Fix long user messages getting cut off in chat view by devin-ai-integration[bot] · Pull Request #25579 · vellum-ai/vellum-assistant

devin-ai-integration · 2026-04-14T18:24:04Z

Removes the aggressive 150pt height-based collapse (userMessageHeightWrapper) that clipped all moderate user messages to ~7-8 lines, causing normal-length messages to appear visually cut off. Moderate messages (< 3,000 chars / < 40 lines) now render at full height, while very large messages continue using the heuristic text-truncation path (1,200 chars / 24 lines preview + "Show more" button) which provides a proper expand flow without height clipping. Also updates the MessageListContentView minHeight estimate to reflect that non-collapsed messages render at full height, fixes an NSString.length vs String.count mismatch in the heuristic threshold check, and replaces the stale 260pt attachment height estimate with per-attachment height estimation.

Requested by: @tkheyfets
Session: https://app.devin.ai/sessions/c92f0be263b4470ebd0a0a5b973002c1

Moderate user messages (< 3,000 chars / < 40 lines) now render at full height without any collapse wrapper. The measurement-based height cap (userMessageHeightWrapper) clipped all user messages to 150pt (~7-8 lines), causing normal-length messages to appear cut off. Very large messages (> 3,000 chars or > 40 lines) continue to use the heuristic text-truncation path (1,200 chars / 24 lines preview with Show more button). Also removes redundant height clipping from the heuristic collapse path that was added in 7e98382, and updates the minHeight estimate in MessageListContentView to reflect that non-collapsed messages render at full height. Closes LUM-833 Co-Authored-By: tkheyfets <timur@vellum.ai>

devin-ai-integration · 2026-04-14T18:24:08Z

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devin-ai-integration · 2026-04-14T18:28:24Z

    @ViewBuilder
    private func heuristicUserMessageCollapseWrapper<Content: View>(@ViewBuilder _ content: () -> Content) -> some View {
        VStack(alignment: .leading, spacing: 0) {
            content()
-                // Clip to same height as the measurement-based collapse path
-                // so both produce a consistent collapsed height.
-                .frame(height: isUserMessageExpanded ? nil : userMessageMaxCollapsedHeight, alignment: .top)
-                .clipped()
-                .overlay(alignment: .bottom) {
-                    if !isUserMessageExpanded {
-                        LinearGradient(
-                            colors: [
-                                VColor.surfaceLift.opacity(0),
-                                VColor.surfaceLift
-                            ],
-                            startPoint: .init(x: 0.5, y: 0),
-                            endPoint: .init(x: 0.5, y: 1)
-                        )
-                        .frame(height: 40)
-                        .allowsHitTesting(false)
-                    }
-                }
            collapseToggleButton
                .padding(.horizontal, VSpacing.lg)
                .padding(.bottom, VSpacing.sm)


🚩 Heuristic collapse wrapper no longer clips content height — relies entirely on text truncation

The old heuristicUserMessageCollapseWrapper had .frame(height: isUserMessageExpanded ? nil : userMessageMaxCollapsedHeight) + .clipped() + gradient overlay. The new version removes all of these, relying entirely on effectiveRenderingText being set to collapsedUserMessagePreviewText (1200 chars / 24 lines + ...) at ChatBubble.swift:669-670. This means the collapsed height is now determined by the preview text's natural rendered height rather than a fixed 150pt cap. The visual result is different: no gradient fade, and the collapsed height varies based on preview text content. The "Show more" button is always visible (not gated on isCollapsible), which is correct since the wrapper is only used when shouldUseHeuristicCollapse is true. One side effect: since attachments (images, files, videos, audio) are rendered inside bubbleChrome at ChatBubble.swift:708-743, they are always displayed at full size even when the text is collapsed — the old height clipping would have hidden them if they were below the 150pt line.

(Refers to lines 593-605)

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Correct — the heuristic collapse wrapper now relies entirely on text truncation (1,200 chars / 24 lines) rather than height clipping. This is intentional: the text truncation provides a proper expand flow with "Show more" button, while the old height clipping just cut content off visually. The attachment visibility change is also intentional — attachments should be visible even when the text portion is collapsed, since they're the primary content the user shared.

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chatgpt-codex-connector · 2026-04-14T18:28:45Z

            if shouldUseHeuristicCollapse {
                heuristicUserMessageCollapseWrapper { chrome }
            } else {
-                userMessageHeightWrapper { chrome }
+                chrome


Keep attachment bubbles in active-turn height calculation

Switching non-heuristic user messages to render chrome directly means attachment messages are no longer collapsed by default, but MessageListContentView.estimatedUserHeight still assumes any attachment message is capped at 260. For large image/file previews this underestimates the real user-row height and inflates turnMinHeight, which can break the active-turn scroll behavior (extra blank space / user message no longer pinned as intended) whenever the latest user message includes attachments.

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Fixed in b2286e3. Removed the stale 260pt early return for attachment messages and added a per-attachment height estimate (~200pt each) to the minHeight calculation for both heuristic-collapsed and non-collapsed paths.

…achment estimate - Use String.count instead of NSString.length for heuristic threshold check to match ChatBubble.shouldUseHeuristicUserCollapse (avoids mismatch with multi-code-unit characters like emoji) - Remove stale 260pt early return for attachment messages; let them fall through to text measurement with per-attachment height estimate - Include attachment height in both heuristic and non-heuristic paths Co-Authored-By: tkheyfets <timur@vellum.ai>

Differentiate by MIME type to match actual rendering heights: - Images: grid layout (~130pt per row, adaptive columns at min 160px) - Videos: ~200pt each (InlineVideoAttachmentView) - Audio: ~60pt each (InlineAudioAttachmentView) - Files: ~40pt each (file chips) Prevents over-estimation that would push turnMinHeight to 0 and break the 'user message pinned at top' scroll invariant. Co-Authored-By: tkheyfets <timur@vellum.ai>

…hresholds Widen access on heuristicUserCollapseCharacterThreshold and heuristicUserCollapseLineThreshold from private to internal so MessageListContentView references the single source of truth. Co-Authored-By: tkheyfets <timur@vellum.ai>

Reflects three-path estimation (no user message, heuristic-collapsed, normal), per-type attachment height, and removed 260pt cap. Co-Authored-By: tkheyfets <timur@vellum.ai>

github-actions · 2026-05-15T09:53:28Z

This PR has been inactive for 30 days. It will be closed in 7 days unless there is new activity.

devin-ai-integration · 2026-05-15T09:53:32Z

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github-actions · 2026-05-22T10:04:16Z

Closed due to inactivity. Feel free to reopen if you'd like to continue working on this.

devin-ai-integration Bot assigned tkheyfets Apr 14, 2026

devin-ai-integration Bot requested a review from tkheyfets April 14, 2026 18:24

devin-ai-integration Bot commented Apr 14, 2026

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docs: update SCROLL_STRATEGY.md MinHeight section to match new formula

28109eb

Reflects three-path estimation (no user message, heuristic-collapsed, normal), per-type attachment height, and removed 260pt cap. Co-Authored-By: tkheyfets <timur@vellum.ai>

devin-ai-integration Bot mentioned this pull request Apr 16, 2026

fix(macos): prevent Show less button from disappearing on user messages #26131

Closed

ashleeradka mentioned this pull request Apr 22, 2026

fix(macos): drive user message collapse from the model, not observed geometry (LUM-1108) #27498

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github-actions Bot added the stale label May 15, 2026

github-actions Bot closed this May 22, 2026

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devin-ai-integration Bot commented Apr 14, 2026 •

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