[Bug]: Linux Wayland (GNOME, Noctalia) overview shows a placeholder icon after AppImage reinstall

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. On Linux Wayland (niri with Noctalia), install or reinstall the T3 Code AppImage with Shelly or AppImageLauncher.
2. Launch T3 Code.
3. Open the compositor overview or workspace switcher.

Expected behavior

The T3 Code window tile shows the T3 icon.

Actual behavior

The tile is a generic glyph. The running window's Wayland app id is com.t3tools.T3Code. That name comes from Electron setDesktopName, which points at the hidden URL-handler desktop file. That file has NoDisplay=true and no Icon=. Noctalia lowercases the app id before lookup, so it also misses com.t3tools.T3Code.desktop.

#2331 appimagelauncher-icons / #2915 appimage-hicolor-icons already ship hicolor sizes inside the AppImage. Those files stay in APPDIR unless something copies them into the user icon theme, so overview still has nothing to resolve after a reinstall.

Impact

Cosmetic issue

Version or commit

Linux Nightly AppImage on current main

Environment

Linux Wayland, niri, Noctalia, AppImage reinstalled with Shelly

Logs or stack traces

# Window identity from niri
app-id: com.t3tools.T3Code

# Hidden handler (rewritten on every start)
~/.local/share/applications/com.t3tools.T3Code.desktop
NoDisplay=true
# no Icon=

# Packaged icons exist in APPDIR usr/share/icons/hicolor/*/apps/t3code.png
# and are not installed under ~/.local/share/icons/hicolor

Workaround

None that survives a restart. T3 rewrites the URL-handler desktop file on every launch.

Start by tracing the Electron entry point that calls setDesktopName and the generated ~/.local/share/applications/com.t3tools.T3Code.desktop file. Inspect how the AppImage packages usr/share/icons/hicolor/*/apps/t3code.png and how icons are installed or exposed after reinstall. Done means a fresh launch leaves a resolvable icon for app-id com.t3tools.T3Code in the Wayland overview, including after restart.