[Bug]: Work log rows jump while a command runs as the timestamp toggles between rows

[jahands]

Before submitting

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

Area

apps/web

Steps to reproduce

1. Start a Claude turn that runs tool calls (here: an Edit followed by a long-running bun turbo ... command).
2. Watch the work log rows under "Running bun" while the command runs.

Expected behavior

The work log rows and the timeline stay put while the command runs.

Actual behavior

The 8:18 AM timestamp on the work log rows keeps appearing and disappearing, and moves between the Edit row and the command row. When it shows on the Edit row, the row's preview text wraps onto a third line (ptr.catalystPoint > ...), so the whole timeline above the composer jumps up and down by one line, several times a second.

Impact

Minor bug or occasional failure

Version or commit

T3 Code (Nightly) 0.0.43-nightly.20260926.2282

Environment

macOS 26.5.2, desktop app, Claude Opus 5.5

Screenshots, recordings, or supporting files

My mouse is not shown in this video, but I'm moving my mouse between the rows - each time causing a layout shift:
https://github.com/user-attachments/assets/4b020d0a-d48e-4806-8701-7c13e2aa79d8

[juliusmarminge]

Triage

Confirmed. This is still the behavior on main. The 0.0.43 nightly from 2026-09-26 is not missing a later fix. No duplicate issue turned up.

The recording is a stationary pointer on the right edge of two rows under "Running bun": an expanded Edit row whose label is the raw tool JSON, and the collapsed cd … bun turbo row. "8:18 AM" hops between those rows for the whole clip. With the timestamp on the Edit row, ptr.catalystPoint > … wraps onto its own line. The command row drops by that line for a frame, then live-follow shifts the rows above up and puts the command row back above the composer. When the timestamp leaves the Edit row, that line goes away and the timeline shifts back. The loop is about once a second. The command output itself is idle.

TimelineRowTimestamp in apps/web/src/components/chat/MessagesTimeline.tsx is absolute and invisible until the row is hovered or focused, then it becomes static and opaque. Entering the flex row takes its width out of the label. The comment above the component says that is so the time does not paint over the text and so the chevron stays put. The row height is not held stable.

An expanded work entry renders its label with whitespace-pre-wrap (PlainWorkEntryRow). A collapsed row uses truncate, so the timestamp only makes the ellipsis arrive sooner and the row stays one line tall. In the recording the Edit label is already two lines while the timestamp is on the command row, and three lines while the timestamp is on the Edit row, so that row is expanded. buildToolCallExpandedBody drops text that is already the visible label, so there is no separate detail block. The JSON in the header is the block that reflows.

That extra line is what moves the pointer onto the other row. The turn is still running, so the timeline is on TIMELINE_MAINTAIN_SCROLL_AT_END_SMOOTH (animated: true while isWorking, around the maintainScrollAtEnd prop on the message list). The list stays pinned to the end: the command row returns to the same place, and everything above it travels one line. After that travel the pointer is over the neighboring row, the timestamp moves, the Edit row loses the line, and the list travels back. The pointer never moves.

#12614 is the same reflow, shown on an expanded command row, and it is still open. It keeps the timestamp in flow on expanded rows (className={expanded ? "static" : undefined}), so hover only changes opacity. That stops this loop. Collapsed rows can keep the absolute-until-hover behavior, because they do not change height.