[BUG] Claude Desktop for Linux: tray icon invisible on dark panels when the desktop color scheme is light — glyph keyed to shouldUseDarkColors, panel theme ignored (Linux sibling of #72622)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version

Version: N/A — Claude Desktop 1.19367.0 (the CLI version field doesn't apply; this is the desktop app)

What's Wrong?

I maintain claude-desktop-debian, which repackages the official Linux .deb into other formats. The tray code here is the official app.asar bytes, unpatched, so this is a first-party bug.

The Linux tray glyph is picked from the system color scheme, not from the color of the panel it actually sits on. So on any desktop where the panel theme is independent of the color scheme, you can end up with a black icon on a dark panel. It's effectively invisible.

In the 1.19367.0 main-process bundle (beautified), the Linux selection site is a single ternary:

oPe() === "gnome" || G.nativeTheme.shouldUseDarkColors
  ? "TrayIconLinux-Dark.png"
  : "TrayIconLinux.png"

The icon-format switch is baked to "png" on Linux, so this is the only Linux selection path. The DE detector oPe() splits XDG_CURRENT_DESKTOP and returns only "kde", "gnome", or "other". Walking through that:

• GNOME gets a hardcoded always-light glyph. That's correct, since GNOME's top bar is always dark.
• KDE is detected but never actually used in the ternary.
• Cinnamon falls through to "other".

So everyone but GNOME gets the glyph keyed to shouldUseDarkColors. But tray visibility depends on the panel color, and on Cinnamon and KDE the panel theme is independent of the color scheme.

I verified it on two desktops.

Cinnamon: LMDE 7 / Linux Mint Cinnamon 6.6.7 with the default Mint theme pairing (Cinnamon panel theme Mint-Y-Dark-Aqua = dark panel, GTK theme Mint-Y-Aqua = light scheme). Result: the black TrayIconLinux.png on a dark panel. This came to us as aaddrick/claude-desktop-debian#604 from @IvanTheGeek, and @mondalaci retested it on 1.19367.0 in our PR #800. A signal that works here: gsettings get org.cinnamon.theme name returns 'Mint-Y-Dark-Aqua' while the color scheme reports light.

KDE Plasma: Nobara 44, Plasma 6.6.4, Wayland session (app on XWayland, the default). I pinned the panel dark (plasma-apply-desktoptheme breeze-dark) and set the color scheme light (plasma-apply-colorscheme BreezeLight; the portal org.freedesktop.appearance color-scheme then reads 2/prefer-light). The tray swapped to the black glyph on the still-dark panel. I measured it over DBus to be sure: the StatusNotifierItem IconPixmap mean luminance of opaque pixels went from 255 (white glyph) to 0 (black glyph), same 1679 opaque pixels both times. So it's the same glyph shape with inverted color, not a different asset.

Windows has the same selector defect: #72622 (open), glyph keyed to nativeTheme instead of the taskbar mode, with earlier #65343 and #41236 closed. The cross-platform pattern is the same: the icon is chosen from the app/system color scheme instead of the surface it sits on.

What Should Happen?

The icon should be chosen to contrast with the panel it renders on. A few options, from most correct to cheapest:

1. Consult the panel-theme signal per DE. The GNOME special-case already shows this is the design intent, and KDE is already detected in oPe(). Cinnamon exposes org.cinnamon.theme name; KDE exposes the Plasma style (plasmarc Theme / kdeglobals).
2. Add a user-facing tray-icon override ("Invert tray icon", or a light/dark/auto picker) in Settings ▸ General under the existing System Tray toggle. This is cheap, user-recoverable, and covers DEs with no probe-able panel signal, like wlroots compositors.
3. Ship a monochrome template icon and let the tray colorize it. That's what #72622 suggests for Windows, and it would collapse all three platforms onto one path.

Error Messages/Logs

(none — the selection is silently wrong-contrast; the only evidence is
visual, plus the DBus IconPixmap luminance probe)

KDE Plasma, over DBus:
  before (dark scheme):  IconPixmap opaque-pixel mean luminance = 255 (white glyph)
  after  (light scheme): IconPixmap opaque-pixel mean luminance = 0   (black glyph)
  opaque pixel count unchanged at 1679 → same shape, inverted color

Steps to Reproduce

KDE Plasma (Wayland or X11):

1. Launch Claude Desktop with the tray enabled.
2. Pin the panel dark: plasma-apply-desktoptheme breeze-dark.
3. Set the color scheme light: plasma-apply-colorscheme BreezeLight.
4. Watch the tray icon swap to a black glyph on the dark panel.

Cinnamon (default Mint pairing):

1. On Linux Mint Cinnamon / LMDE with the stock Mint-Y-Dark-Aqua panel theme and Mint-Y-Aqua (light) GTK theme.
2. Launch Claude Desktop with the tray enabled.
3. The black TrayIconLinux.png lands on the dark panel.

For what it's worth, we ship an interim launcher workaround downstream (an env flag threaded into the selector, aaddrick/claude-desktop-debian#800). Happy to delete it the moment this is fixed upstream.