tmux inside an AWS SSM session forces white cursor

[NicosGollan-cnic]

Windows Terminal version

1.21.10351.0

Windows build number

10.0.26100.0

Other Software

gossm v1.5.0
tmux 3.0a
ubuntu 20.04, 22.04, 24.04

Steps to reproduce

• Inside a WSL Linux session in Terminal (Ubuntu)
• Connect to an AWS EC2 instance running Ubuntu 20.04
  
• Start a tmux session
  

Expected Behavior

I expect the cursor colour to remain the same. Normally, I have a dark blue cursor on a light background.

Actual Behavior

The cursor is forced to pure white when starting or terminating the tmux session.

Opening Terminal settings and saving them without any changes restores the cursor to the intended colour, and it remains that way for the remainder of the tmux session.

This does not happen when running tmux "natively" in the "parent" WSL terminal, so far I only encountered the behaviour when running tmux in an SSM session.

[lhecker]

Thanks! Would you mind grabbing us the output of the debug tab? https://github.com/microsoft/terminal/wiki/Troubleshooting-Tips#enabling-the-debug-tap

In particular, look out for OSC 12: ␛]12.

[NicosGollan-cnic]

Hey, thanks for the response, below is what happens when I start tmux in a gossm-initiated session, starting with the prompt where I enter "tmux". I hope that's enough since I don't exactly feel like redacting various IDs from a tonne of raw ANSI terminal :-)

In particular, after sending the prompt, there appears to be this sequence before it runs off to the tmux status line, starting with the "$ " of the prompt: $␣␛[O␛[?12l␛[?25l␛[30m␛[42m

␛[13;28;13;0;32;1_␛[32m␛[1mapp@cron␛[m:␛[34m␛[1m/var/snap/amazon-ssm-agent/9881␛[m$␣␛]0;app@cron:␣/var/snap/amazon-ssm-agent/9881␇␛[84;20;116;1;32;1_t␛[84;20;116;0;32;1_␛[77;50;109;1;32;1_m␛[77;50;109;0;32;1_␛[85;22;117;1;32;1_u␛[85;22;117;0;32;1_␛[88;45;120;1;32;1_x␛[88;45;120;0;32;1_␛[32;57;32;1;32;1_␣␛[32;57;32;0;32;1_␛[13;28;13;1;32;1_␍␊
␛[?1049h␛[22;0;0t␛[?1h␛=␛[2J␛[?12l␛[?1000l␛[?1002l␛[?1006l␛[?1005l␛[?12;25h␛[?12l␛[?1003l␛[?1006l␛[?2004l␛]112␇␛[?25l␛[H␛[K␍␊
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[33]␣0:tmux*␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣"cron.eu-central-1a.li"␣08:08␣20-Mar-25␛[H␛[?25h␛[mapp@cron:/var/snap/amazon-ssm-agent/9881$␣␛[O␛[?12l␛[?25l␛[30m␛[42m␛[68;1H[33]␣0:bash*␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣"cron.eu-central-1a.li"␣08:08␣20-Mar-25␛[1;43H␛[?25h␛[I␛[?12l␛[?25l␛[m␛[30m␛[42m␛[68;1H[33]␣0:bash*␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣"cron.eu-central-1a.li"␣08:09␣20-Mar-25␛[1;43H␛[?25h␛[O

[DHowett]

Hey, funny enough... this is something we expressly added support for!

I see ␛]112␇ in your trace output.

According to the big document of control sequences, this is the code for "Reset Cursor Color". Something in your remote config is requesting that we reset the cursor color.

[DHowett]

FWIW,

[NicosGollan-cnic]

What does it "reset to" though? By default, I have that dark blue colour everywhere, and saving settings even restores it, so my expectation would be that any "reset" would restore it to that dark colour instead of white.

[DHowett]

You know what? You're right. It's resetting to a built-in default because we don't actually fully support the reset OSC.

We're tracking that over in /dup #3719, and I just started work on it (you caught me on a bored Thursday with some extra time...)

[microsoft-github-policy-service]

Hi! We've identified this issue as a duplicate of another one that already exists on this Issue Tracker. This specific instance is being closed in favor of tracking the concern over on the referenced thread. Thanks for your report!