Copilot sends literal ^U character to Terminal instead of executing "Clear Line" command

[GX-Swjtu]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Copilot in GitHub

Body

Description:
When GitHub Copilot (Terminal Chat or Inline Chat) attempts to execute a command in the VS Code Terminal, it frequently prepends a literal ^U character to the command string.

This causes the command to fail because the shell (specifically PowerShell) treats ^U as part of the command rather than a control sequence to clear the current line. This further leads the AI to hallucinate or troubleshoot based on a "command not found" error caused by this prefix.

Steps to Reproduce:

Open VS Code with GitHub Copilot extension installed.

Open a PowerShell terminal.

Use Copilot to run a command in the terminal (e.g., via Terminal Chat or "Run in Terminal" feature).

Observe the terminal input.

Expected Behavior:
Copilot should either clear the line silently using a proper terminal sequence or simply paste the command if the line is already empty.

Actual Behavior:
The terminal shows ^U& 'path/to/command' (as seen in the attached screenshots). The ^U remains as text, causing a syntax error in PowerShell.

Environment:

版本: 1.119.0 (system setup)
提交: 8b640eef5a6c6089c029249d48efa5c99adf7d51
日期: 2026-05-05T11:23:50-07:00
Electron: 39.8.8
ElectronBuildId: 13870025
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26200

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[elimumford]

Work around: Tell the agent to prefix commands with "; ", initial run still has syntax error, but actual command executes.

[twitthoeft-gls]

+1
|
I am seeing the same behavior. VS Code CoPilot using Claude model always prepends the ^U character to powershell commands. Creates a lot of token churn and is slowing down / confusing the agent.

[Devofsky]

I was able to resolve this by configuring PSReadLine to handle Ctrl+U explicitly.

PowerShellSet-PSReadLineKeyHandler -Key 'Ctrl+u' -Function BackwardDeleteLine

This prevents ^U (0x15) from being inserted as a literal control character and instead makes it behave like "delete to beginning of line" (similar to many Linux shells).
You can persist this change by adding it to your PowerShell profile.