Per-output `awww` wallpaper on HDMI HDR monitor causes flicker/artifacts

# Per-output `awww` wallpaper on HDMI HDR monitor causes flicker/artifacts ## Summary On a dual-monitor Hyprland setup, setting wallpapers with per-output `awww img --outputs ...` appears to trigger intermittent compositor flicker/artifacts on the external HDMI monitor. Using a single global `awww img ...` command with the same animated wallpaper and transition avoids the issue. The internal eDP display does not show the same problem. The issue appears tied to the external HDMI/HDR output path and per-output wallpaper assignment. ## Environment - Machine: MSI Bravo 15 C7V - OS: NixOS `26.05.20260510.da5ad66 (Yarara)` - Kernel: `Linux nixos 6.18.28 #1-NixOS SMP PREEMPT_DYNAMIC Fri May 8 06:40:23 UTC 2026 x86_64 GNU/Linux` - CPU: AMD Ryzen 5 7535HS with Radeon Graphics - GPU modules loaded: `nvidia`, `nvidia_drm`, `nvidia_modeset`, `nvidia_uvm`, `amdgpu` - `awww`: `0.12.1` - Hyprland: `0.55.0`, commit `805f7bf48e46dcab20c0b45844ae36aac354b4bd` Hyprland library versions: ```text Hyprgraphics: built against 0.5.1 Hyprutils: built against 0.13.1 Hyprcursor: built against 0.1.13 Hyprlang: built against 0.6.8 Aquamarine: built against 0.11.0 ``` ## Monitor Setup External monitor: ```text Monitor HDMI-A-1: 3440x1440@100.00000 at 1920x0 make/model: YSN Z34D scale: 1.00 currentFormat: XBGR2101010 colorManagementPreset: hdr sdrBrightness: 0.60 sdrSaturation: 1.15 sdrMaxLuminance: 450 vrr: false ``` Internal monitor: ```text Monitor eDP-1: 1920x1080@144.00301 at 0x0 make/model: Chimei Innolux Corporation 0x1521 scale: 1.00 currentFormat: XBGR2101010 colorManagementPreset: srgb sdrBrightness: 0.70 sdrSaturation: 1.11 sdrMaxLuminance: 400 vrr: true ``` Relevant Hyprland monitor config: ```lua hl.monitor({ output = "eDP-1", mode = "1920x1080@144", position = "0x0", scale = 1, bitdepth = 10, sdr_eotf = "gamma22", sdrbrightness = 0.7, sdrsaturation = 1.11, supports_wide_color = 1, sdr_min_luminance = 0.001, sdr_max_luminance = 400, vrr = 1, }) hl.monitor({ output = "HDMI-A-1", mode = "3440x1440@100", position = "1920x0", scale = 1, bitdepth = 10, cm = "hdr", sdrbrightness = 0.6, sdrsaturation = 1.15, supports_wide_color = 1, supports_hdr = 1, sdr_min_luminance = 0.001, sdr_max_luminance = 450, vrr = 1, }) ``` ## Reproduction With both monitors connected, start `awww` using per-output wallpaper commands: ```sh uwsm app -- awww img --outputs eDP-1 /home/skydive420dz/nixos-dotfiles/wallpapers/wallpaper-003.gif --transition-type fade uwsm app -- awww img --outputs HDMI-A-1 /home/skydive420dz/nixos-dotfiles/wallpapers/wallpaper-008.jpg --transition-type fade ``` Observed behavior: - The external HDMI monitor shows intermittent compositor flicker/artifacts. - Artifacts are easiest to notice on an empty desktop/plain background. - The internal eDP panel is stable. - The behavior looked like compositor/layer glitches at first, but persisted after simplifying the shell. Then stop/reset `awww` and set one global wallpaper instead: ```sh uwsm app -- awww img /home/skydive420dz/nixos-dotfiles/wallpapers/wallpaper-003.gif --transition-type fade ``` Observed behavior: - Flicker/artifacts stop. - HDR can remain enabled on `HDMI-A-1`. - The same transition type (`fade`) is kept. - The desktop stays stable with the global wallpaper command. ## Expected Behavior Per-output wallpaper assignment should not cause flicker/artifacts on the external HDMI HDR monitor. ## Actual Behavior Using per-output wallpaper assignment appears to trigger intermittent visual artifacts/flicker on the HDMI HDR output. Using a global wallpaper assignment avoids the issue. ## Notes - The external monitor uses HDR color management and 10-bit format (`XBGR2101010`). - The issue appears output-specific: eDP is stable, HDMI is affected. - The current workaround is to use a single global `awww img ...` call instead of separate `--outputs` calls. - `lspci` was not available during data collection, but GPU-related loaded modules include both NVIDIA and AMDGPU modules. Raw command outputs are available in the attached report bundle. ## Current Workaround Current working Hyprland startup command: ```lua hl.exec_cmd( "uwsm app -- awww img /home/skydive420dz/nixos-dotfiles/wallpapers/wallpaper-003.gif --transition-type fade" ) ```