google-gemini/gemini-cli

Bug: image paste fails in WSL2 when clipboard exposes image/bmp and XDG_SESSION_TYPE is unset

Open

#22274 opened on Mar 13, 2026

View on GitHub
 (11 comments) (0 reactions) (1 assignee)TypeScript (103,992 stars) (13,657 forks)batch import
area/coreeffort/mediumhelp wantedkind/bugpriority/p2status/bot-triagedtype/bug

Description

What happened?

I am running Gemini CLI inside WSL2 Ubuntu on a Windows 11 host, launched from Windows Terminal.

When I copy an image on Windows and press Alt+V inside gemini running in WSL2, image paste fails.

After debugging, I found that in this WSL2 environment:

  • XDG_SESSION_TYPE is unset
  • WAYLAND_DISPLAY=wayland-0
  • DISPLAY=:0

When an image is copied on Windows, the Linux clipboard side exposes image/bmp rather than image/png.

This suggests Gemini CLI's Linux clipboard image handling is not fully compatible with this WSL2 case.

What did you expect to happen?

I expected Alt+V image paste to work in WSL2 when the clipboard contains an image.

Gemini CLI should ideally:

  • detect the clipboard backend even when XDG_SESSION_TYPE is unset
  • fall back to WAYLAND_DISPLAY / DISPLAY in WSL2-like environments
  • accept the actual image MIME type exposed by wl-paste / xclip
  • handle image/bmp gracefully, for example by converting it internally to PNG before attaching

Client information

Client information

CLI Version: 0.33.1 Platform: Linux OS: Ubuntu 24.04.3 LTS Kernel: Linux momo 6.6.87.2-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025 x86_64 GNU/Linux Sandbox Environment: no sandbox Model Version: auto-gemini-3 (configured) Selected Auth Type: oauth-personal GCP Project: [not set] IDE Client: [none] User Email: ***@gmail.com

Additional environment:

  • Host OS: Windows 11
  • Terminal: Windows Terminal
  • TERM=xterm-256color
  • XDG_SESSION_TYPE is unset
  • WAYLAND_DISPLAY=wayland-0
  • DISPLAY=:0

Clipboard behavior observed during reproduction:

  • When an image is copied on Windows, the Linux clipboard side exposes image/bmp

Login information

Google Account login (oauth-personal)

Anything else we need to know?

Steps to reproduce

  1. Copy an image into the Windows clipboard

  2. Open Windows Terminal

  3. Enter WSL2 Ubuntu

  4. Run:

    echo "XDG_SESSION_TYPE=$XDG_SESSION_TYPE"
echo "WAYLAND_DISPLAY=$WAYLAND_DISPLAY"
echo "DISPLAY=$DISPLAY"
wl-paste --list-types

  5. Start Gemini CLI:

    gemini

  6. Press Alt+V

Notes

A local compatibility patch that:

  • falls back to WAYLAND_DISPLAY / DISPLAY when XDG_SESSION_TYPE is unset
  • accepts image/bmp and converts it internally to PNG

made the same workflow work correctly in the same environment.

The same Windows clipboard image became attachable in the same WSL2 environment after that local compatibility patch. This makes the issue look like a Gemini CLI Linux/WSL clipboard compatibility gap rather than a Windows clipboard bridge problem.

Contributor guide

Tech stack
typescriptnodejs
Domain
cli
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Familiarity with Linux clipboard tools (wl paste, xclip)Basic understanding of WSL2 environment
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate clipboard backend detection in the Gemini CLI when XDG SESSION TYPE is unset. The issue indicates that on WSL2, the clipboard exposes image/bmp instead of image/png. Look at the source code for clipboard handling, likely in a file related to clipboard or Wayland/X11 integration. Modify detection logic to fall back to WAYLAND DISPLAY or DISPLAY when XDG SESSION TYPE is unset, and add support for image/bmp by converting it to PNG before attaching. Test the fix in a WSL2 Ubuntu environment with Windows Terminal.