wron "primary" screen

[schmurfy]

I have a 1080p screen on the left and my main 1440p screen on its right, I use this kanshi config:

profile "Dual monitor" {
  output "HDMI-A-1" mode 1920x1080@60Hz position 0,0
  output DP-2 mode 2560x1440@120Hz adaptive_sync on position 1920,0
}

The issue is that when I start a game on steam, the game picks up the 1080p resolutions despite starting on the 1440p screen. for windows game I found a workaround by setting a virtual screen with winecfg but today I bought my first Linux native game and I can't find the real fix to my issue...

I tried swapping the screen (DP-2 at 0,0 and HDMI-A-1 at -1920,0) but it didn't change anything, for some reason the left screen stays the main one.

I am willing to test anything at this point if you have any ideas.

PS: I was using monitorrule initialy in a previous version of mangowc but I changed to kanshi after other issues and the doc saying to avoid using it (I already had the same steam issues)

[h-kod]

The reason the left monitor stays "primary" for games even after swapping positions in kanshi: Wayland compositors pick the primary/output-for-fullscreen based on their own output order/priority, not on kanshi's layout coordinates. Kanshi only positions outputs; it doesn't designate which one is primary.

Things to try with mango:

1. If mango still honors monitorrule internally for workspace/output ordering, define your 1440p output there as primary even if kanshi handles mode/position — several mangowc forks kept that rule for exactly this purpose.
2. Check mango's startup output order: the first enabled output usually becomes primary. You can force ordering by listing outputs explicitly in mango's config rather than relying on hotplug detection order.
3. For the Steam/Proton case specifically, SDL games often read SDL_VIDEO_FULLSCREEN_DISPLAY / Steam uses the display Steam itself starts on. Try launching with SDL_VIDEO_FULLSCREEN_DISPLAY=1 (index of DP-2) to confirm the game is capable of picking the right screen and it's purely a primary-output problem.
4. Also verify with wlr-randr (or MangoWC's IPC) what the compositor reports as primary at runtime — if it reports HDMI-A-1 regardless of layout, that confirms rule 窗口表面支持动画缩放 #2.

Since native games ignore winecfg's virtual screen workaround, the real fix has to be at the compositor level: make DP-2 the primary/first output.