[Bug] Buzz AppImage desktop not displaying properly in Linux

[SaptarshiSarkar12]

Describe the bug
When I run the Buzz desktop AppImage downloaded from buzz releases, it opened, downloaded pocket tts model but the app never displayed the main window properly.

To Reproduce:
Steps to reproduce the behavior:

1. Download Buzz AppImage
2. Make sure its executable
3. Run the AppImage from the terminal
4. A blue window opens, pocket tts is downloaded and then the window suddenly becomes transparent. The window never loads properly.

Expected behavior:
The buzz desktop window should be shown.

Supporting Material

Screencast.From.2026-07-25.09-11-28.mp4

Environment (please complete the following information):

• OS: Fedora workstation 44
• Linux fedora 7.1.4-204.fc44.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Jul 22 16:25:06 UTC 2026 x86_64 GNU/Linux

Additional context
Terminal logs:

1. First Run:

buzz-desktop: persisted identity pubkey 1c99aea82f72437cdd54c076f358a5332b4fd251fbac1a007233915bc44c1e94
buzz-desktop: repos dir resolved at boot — no configured override, REPOS is the default real dir
buzz-desktop: media proxy listening on 127.0.0.1:35271
buzz-desktop: downloading Pocket TTS decoder.onnx from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/decoder.onnx
././/include/c++/12/bits/stl_vector.h:1123: constexpr std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = {anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop; _Alloc = std::allocator<{anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop>; reference = {anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop&; size_type = long unsigned int]: Assertion '__n < this->size()' failed.
buzz-desktop: downloaded 41478706 bytes (decoder.onnx), wrote to disk
buzz-desktop: downloading Pocket TTS encoder.onnx from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/encoder.onnx
buzz-desktop: downloaded 72713165 bytes (encoder.onnx), wrote to disk
buzz-desktop: downloading Pocket TTS lm_flow.onnx from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/lm_flow.onnx
buzz-desktop: downloaded 39097094 bytes (lm_flow.onnx), wrote to disk
buzz-desktop: downloading Pocket TTS lm_main.onnx from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/lm_main.onnx

** (buzz-desktop:23056): WARNING **: 08:58:30.009: atk-bridge: get_device_events_reply: unknown signature
buzz-desktop: downloaded 302742148 bytes (lm_main.onnx), wrote to disk
buzz-desktop: downloading Pocket TTS text_conditioner.onnx from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/text_conditioner.onnx
buzz-desktop: downloaded 16388343 bytes (text_conditioner.onnx), wrote to disk
buzz-desktop: downloading Pocket TTS vocab.json from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/vocab.json
buzz-desktop: downloaded 69478 bytes (vocab.json), wrote to disk
buzz-desktop: downloading Pocket TTS token_scores.json from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/token_scores.json
buzz-desktop: downloaded 123616 bytes (token_scores.json), wrote to disk
buzz-desktop: downloading Pocket TTS LICENSE from https://huggingface.co/csukuangfj2/sherpa-onnx-pocket-tts-2026-01-26/resolve/96d1e53ce3311ca6c2c6a35e2062d36b4cec6fa3/LICENSE
buzz-desktop: downloaded 18655 bytes (LICENSE), wrote to disk
buzz-desktop: downloading Pocket TTS reference_sample.wav from https://huggingface.co/kyutai/tts-voices/resolve/323332d33f997de8394f24a193e1a76df720e01a/vctk/p333_023_enhanced.wav
buzz-desktop: downloaded 639084 bytes (reference_sample.wav), wrote to disk
buzz-desktop: Pocket TTS model ready at /home/saptarshi/.buzz/models/pocket-tts

2. Second Run:

buzz-desktop: persisted identity pubkey 1c99aea82f72437cdd54c076f358a5332b4fd251fbac1a007233915bc44c1e94
buzz-desktop: repos dir resolved at boot — no configured override, REPOS is the default real dir
buzz-desktop: media proxy listening on 127.0.0.1:38281
././/include/c++/12/bits/stl_vector.h:1123: constexpr std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = {anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop; _Alloc = std::allocator<{anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop>; reference = {anonymous}::colrv1_configure_skpaint(FT_Face, const SkSpan<unsigned int>&, SkColor, const FT_COLR_Paint&, SkPaint*)::<lambda(const FT_ColorStopIterator&, std::vector<float>&, std::vector<SkRGBA4f<kUnpremul_SkAlphaType> >&)>::ColorStop&; size_type = long unsigned int]: Assertion '__n < this->size()' failed.

** (buzz-desktop:25678): WARNING **: 09:11:55.634: atk-bridge: get_device_events_reply: unknown signature

[JuxhinDB]

Reproducing the same bug. Fedora 44.

[leolaporte]

Root cause analysis (from local debugging on Sway/wlroots + X11)

This is not a GPU, Mesa, EGL, or wlroots compositor issue. The root cause is in the Tauri window configuration.

desktop/src-tauri/tauri.conf.json (v0.4.26) sets on the main window:

"transparent": true,
"titleBarStyle": "Overlay",
"hiddenTitle": true,
"visible": false

The opaque backing that makes transparency survivable is macOS-only. In desktop/src-tauri/src/lib.rs:

• set_initial_window_backing() (sets Color(17,21,24,255)) — #[cfg(target_os = "macos")], line 82
• clear_initial_window_backing() — #[cfg(target_os = "macos")], line 92
• the initial-render-ready gate — #[cfg(target_os = "macos")], line 69
• non-macOS path, line 232: #[cfg(not(target_os = "macos"))] { reveal_initial_window(&window); } — shows the window immediately, with no opaque backing

There is no tauri.linux.conf.json, so transparent: true applies to Linux unmodified. The window is created with an alpha channel and nothing at the toolkit level paints behind it. macOS hides this behind vibrancy; Wayland compositors (Sway/wlroots) honor the alpha exactly, so you see the desktop through it. X11's RGBA visual with no backing store produces "half transparent, half black."

Since transparent is compiled into the binary from tauri.conf.json, the AppImage cannot be fixed by env vars, CLI flags, or backend selection.

Suggested fix

Add desktop/src-tauri/tauri.linux.conf.json with:

{
  "app": {
    "windows": [
      {
        "transparent": false
      }
    ]
  }
}

Tauri 2 merges platform-specific config at build time. Linux has no vibrancy backdrop, so nothing is lost.

Alternative: widen set_initial_window_backing to #[cfg(not(target_os = "macos"))] and never call clear_initial_window_backing on non-macOS.

Additional note on the AppImage test matrix

squashfs-root/apprun-hooks/linuxdeploy-plugin-gtk.sh hardcodes export GDK_BACKEND=x11 (no ${GDK_BACKEND:-x11} default), which clobbers any user-set backend. This means Wayland-backend testing via the AppImage is impossible without modifying the bundle — worth knowing for future debugging, though it isn't the cause here.