Desktop app Code tab: transcript text reflows by the activity spinner's width every time it appears or disappears

Title: Desktop app Code tab: transcript text reflows by the activity spinner's width every time it appears or disappears

Environment

• Claude desktop app, Code tab (Linux, Arch; app build as of 2026-10-09)
• Transcript view: reproducible in "normal", much worse in "verbose" and "thinking"

What happens

While Claude is working, the orange activity spinner is laid out inline with the message
column rather than overlaid on it. Each time the spinner mounts or unmounts, the column's
left edge moves by the spinner's width and every line of text reflows, so the transcript
jitters between two line-wrap positions for the whole turn. In verbose view this happens
once per tool call and per thinking block, i.e. dozens of times per turn, which makes the
transcript hard to read while it is being written.

Steps to reproduce

1. Open any Code session; switch the transcript view to "verbose" (title-bar menu).
2. Ask for something that runs several tool calls in a row.
3. Watch the left margin of the existing messages: it shifts right when the spinner

appears and back when it disappears, and the text re-wraps each time.

Expected

The message column keeps a fixed left edge whether or not the spinner is showing.

Suggested fix

Either reserve the gutter (keep the spinner element in the layout with visibility: hidden
or a fixed-width placeholder when idle) or position the spinner absolutely so it does not
participate in the column's layout.

Notes

Closing the terminal side pane does not affect it; switching to "normal" view only reduces
how often it happens. Reference ID from /feedback (bundle not attached): cc-20261009-180654-cc2c5b