[Bug]: Expanded Lineage workflow overflows the fixed-width details card horizontally #27553

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to investigate the problem.

Area

apps/web, shared by the desktop client.

Problem

Expanding a workflow in the right-hand thread details card makes Lineage overflow horizontally. The card remains narrow and the user cannot widen it to read the contents.

The reporter supplied a screenshot of a roughly 280 px wide details card. The expanded workflow shows a Research phase, 1/3 agents, and an elapsed time such as 4m 57s. The phase chevron is cut off at the right edge, a horizontal scrollbar appears below the member rows, and the workflow title is truncated. The user specifically asked why scrolling is necessary when the card cannot be resized.

Steps to reproduce

Based on the reported state, not a fresh independent runtime reproduction:

1. Open a thread with a phased Claude workflow containing several member agents.
2. Open the right-hand thread details card.
3. Expand the workflow under Lineage, then its running phase.
4. Observe the phase header containing the phase title, agent count, elapsed time, and chevron.

The supplied screenshot has a short phase title, Research, and three members. Long phase names should not be necessary to hit this.

Expected behavior

Lineage rows fit within the default details card width. The phase toggle and status information remain visible without horizontal scrolling. Labels and metadata should shrink, wrap, or use a more compact layout as appropriate.

The reporter also wants a way to widen the details card to read longer workflow and agent labels. Please consider that sizing request alongside the overflow bug.

Actual behavior

The expanded phase header runs beyond the right edge and introduces horizontal scrolling inside the narrow card. There is no visible resize handle to recover the missing space.

Source investigation

Inspected upstream main at 32ecd71726fee16f335484c1f95cbce126d461f6:

• threadDetailsCardLayout.ts fixes the inline card width at 280 px. The CSS counterpart is --thread-details-panel-width: 17.5rem.
• ThreadLineageWorkflowRow.tsx indents phase content with ps-6.5 and renders the count and elapsed time as separate shrink-0 accessories.
• CollapsibleSectionHeader also makes the label non-shrinking, retains a minimum-width spacer, and uses a non-shrinking chevron. This combination is a likely source of the overflow at the card's default width.
• ScrollArea permits overflow in both directions.

This is source analysis plus the reporter's screenshot, not a verified browser reproduction. No application code or running installation was changed.

Impact

Minor bug or occasional failure. The user must scroll sideways to reach clipped workflow controls in a card that cannot be widened.

Version or commit

Windows x64 desktop environment reports T3 server 0.1.3; connected Linux environment has runtime 0.1.2. The exact renderer build used for the screenshot has not been independently confirmed. Source investigation uses main at 32ecd71726fee16f335484c1f95cbce126d461f6.

Screenshots, recordings, or supporting files

The reporter supplied a 339 × 596 screenshot in the reporting session. It is described above; it is not attached here because the available issue tool does not upload binary attachments.

Workaround

None verified. Collapsing the workflow hides the affected rows.

Filed by Codex, GPT-6.1-Sol, on the reporter's behalf.