[Bug] 1.0.49: submitted user messages render with a gray background block in scrollback

[cwedgwood]

[Bug] 1.0.49: submitted user messages render with a gray background block in scrollback

Describe the bug

After upgrading from 1.0.48 to 1.0.49, every submitted user message in the chat scrollback (the
❯ <text> lines above the live input) is now rendered with a dark-gray block painted behind it.
The block makes the chevron and text low-contrast and unpleasant to read against my
otherwise-clean terminal background. The live input box itself looks fine — only the
previously-submitted prompts that have scrolled into the chat history are affected.

The same terminal and the same environment rendered cleanly on 1.0.48 for many days. The change
appeared the moment I upgraded to 1.0.49.

Affected version

1.0.49 (Linux x64). Not present on 1.0.48 in the same environment.

Steps to reproduce

1. Start copilot (see "Environment" below for my exact terminal config).
2. Send any prompt, e.g. hello.
3. After the agent responds, look at the submitted prompt now sitting in the scrollback — it has a
   dark-gray rectangle behind the entire row.

Expected behavior

Submitted prompts render against the terminal's background, with no painted block behind them. This
is how 1.0.48 behaved.

Workaround

Setting COLORTERM=truecolor in the environment and restarting did not eliminate the gray
background in my setup — a gray block was still painted, possibly a different shade. I have not
found a configuration-only workaround.

Environment (from copilot --print-debug-info)

v1.0.49 linux x64
isTTY:  true
isLocalTerminal()  = true
isRemoteTerminal() = false
isVSCodeTerminal() = false

TERM         = xterm
COLORTERM    = <unset>
TERM_PROGRAM = <unset>
WT_SESSION   = <unset>
SSH_*        = <unset>
TMUX         = <unset>
NO_COLOR     = <unset>
FORCE_COLOR  = <unset>

Host terminal: alacritty. Reproduced inside a Docker container whose entrypoint sets TERM=xterm
and does not propagate COLORTERM.

Additional context

I could not find a changelog entry between 1.0.48 and 1.0.49 mentioning any change to user-message
rendering, scrollback styling, or background colors. I don't know what changed.

Related but distinct: #2123 (fine-grained per-element theming) — there does not appear to be any
user-facing setting today to disable per-row backgrounds.

[taxnu]

Getting same experience - screenshot - You can see my input w/ >:

The block makes the chevron and text low-contrast and unpleasant to read against my
otherwise-clean terminal background.

Yes - perfect wording.

[charlie-hebert]

Same issue that's especially bad in tmux:

v1.0.48

v1.0.49