# Niri Display Rotation Workflow

Used to rotate/flip external monitors in portrait mode.

## Workflow
1. `niri msg outputs` — capture current transform, logical size, scale, position.
2. Read `~/.config/niri/cfg/display.kdl`.
3. Edit `transform` values.
4. `niri validate -c ~/.config/niri/cfg/display.kdl` — dry-run validation.
5. `niri msg action load-config-file` — hot-reload (no restart).
6. `niri msg outputs | grep -E '^Output|Transform|Logical|Scale'` — verify.
7. `git add && git commit && git push` in dotfiles repo (`~/.omp`).

## Critical pitfall
- In portrait, "flip 180°" = swap `90° counter-clockwise` ↔ `270° counter-clockwise`.
- Setting `transform "180"` on a portrait monitor kicks it to landscape-upside-down.
- Niri transform values are absolute, NOT modular arithmetic.

## Verified layout (blankpad, 83c9c92)
- DP-2: x=0, portrait 1200x1920, transform 90° CCW, scale 1
- HDMI-A-1: x=1200, portrait 1200x1920, transform 270° CCW, scale 1
- eDP-1: x=2400, 1536x864, scale 1.25

## Config split
- `~/.config/niri/cfg/*.kdl` (Noctalia-style includes).
- Display config lives in `~/.config/niri/cfg/display.kdl`.