Unexpected backslash with OSC 9;9 prompt

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

1. Configure OSC 9;9 for PowerShell and add custom prompt in $PROFILE following https://learn.microsoft.com/en-us/windows/terminal/tutorials/new-tab-same-directory#powershell-powershellexe-or-pwshexe:

function prompt {
  $loc = $executionContext.SessionState.Path.CurrentLocation;

  $out = "PS $loc$('>' * ($nestedPromptLevel + 1)) ";
  if ($loc.Provider.Name -eq "FileSystem") {
    $out += "$([char]27)]9;9;`"$($loc.ProviderPath)`"$([char]27)\"
  }
  return $out
}

1. Type a single quote ' or a dot .

Expected behavior

PS> '

Actual behavior

PS>\'

Error details

No response

Environment data

PS /home/yen/tmp/PowerShell> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.4.0-preview.3
PSEdition                      Core
GitCommitId                    7.4.0-preview.3
OS                             Linux 6.3.8-arch1-1 PowerShell/PowerShell#1 SMP PREEMPT_DYNAMIC Wed, 14 Jun 2023 20:10:31 +0000
Platform                       Unix
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

I can also reproduce the issue with PowerShell 7.3.4 on Windows 10 22H2.

Visuals

This is captured with Konsole 23.04.2 and tmux 3.3a. I can reproduce the same issue with PowerShell 7.3.4 on Windows 10 22H2.

[daxian-dbw]

Unfortunately, we don’t own that doc.

[daxian-dbw]

I can reproduce the issue after moving the prompt function to $PROFILE. We will investigate it.