Configure the Kuycon by what it is, not where it is plugged in

The panel's 4500x3000 mode, 1.5 scale, and 10-bit request were a rule
for connector DP-2 outright, which handed them to whatever monitor a
stranger's machine had on its most common DisplayPort connector. The
rule is now matched by description, the per-output prefs loop covers
every connector including DP-2, and the displays contract pins the
policy to the description rather than the port.

config/dot/hypr/README.md

@@ -29,7 +29,7 @@ Don't "fix" them.
 | `hyprland.lua` | Entry point. Each `require()` is its own error scope |
 | `prefs.lua` | Reads the settings file the Settings app writes. See below |
 | `env.lua` | Environment. Note the uwsm caveat below |
-| `monitors.lua` | DP-2 geometry, scaling, and the HDR decision |
+| `monitors.lua` | Monitor geometry and scaling (the Kuycon by description), and the HDR decision |
 | `looks.lua` | Colors, blur, glow, shadows, animations, VRR, scanout |
 | `input.lua` | Keyboard/mouse. Click-to-focus, like GNOME |
 | `rules.lua` | Window rules, gaming rules, layer rules for the shell |

config/dot/hypr/monitors.lua

@@ -1,7 +1,7 @@
 -- ─────────────────────────────────────────────────────────────────────────────
 -- Monitors
 --
--- Kuycon P20 on DP-2: 4500x3000 @ 60Hz, 1.5x fractional scale.
+-- Kuycon P20 (matched by description): 4500x3000 @ 60Hz, 1.5x fractional scale.
 -- 4500/1.5 = 3000 and 3000/1.5 = 2000, both integers, so this is a "clean"
 -- fractional scale and Hyprland will not complain.
 --
@@ -125,32 +125,10 @@ local function display_position(entry, fallback)
     return fallback
 end
 
-local shipped_mode = "4500x3000@60"
+-- Every connected output uses the same validated per-output store. Automatic
-local shipped_scale = 1.5
+-- placement and the compositor's normal color policy unless the entry says
-local shipped_transform = 0
+-- otherwise.
-local dp2 = display_entry("DP-2")
-
-hl.monitor({
-    output   = "DP-2",
-    mode     = dp2 and dp2.mode or shipped_mode,
-    position = display_position(dp2, "0x0"),
-    scale    = dp2 and dp2.scale or shipped_scale,
-    transform = dp2 and dp2.transform or shipped_transform,
-
-    -- 10-bit output. 4500x3000@60 at 10bpc is ~24 Gbps, right at the edge of
-    -- DP 1.4 HBR3, so this relies on DSC. If the display fails to light up or
-    -- falls back to a lower mode, drop this line first.
-    bitdepth = 10,
-
-    -- "auto" = sRGB at 8bpc, wide gamut at 10bpc. Not HDR; see header.
-    cm = "auto",
-})
-
--- Other connected outputs use the same validated per-output store. They keep
--- automatic placement and the compositor's normal color policy; DP-2 alone
--- carries the panel-specific 10-bit policy documented above.
 for output, _ in pairs(displays) do
-    if output ~= "DP-2" then
     local entry = display_entry(output)
     if entry ~= nil then
         hl.monitor({
@@ -162,7 +140,32 @@ for output, _ in pairs(displays) do
         })
     end
 end
-end
+
+-- The Kuycon P20, matched by what it is rather than where it is plugged in.
+-- This used to be a rule for connector DP-2 outright, which handed the panel's
+-- 4500x3000 mode and 1.5 scale to whatever monitor a stranger's machine had on
+-- its most common DisplayPort connector. Emitted after the prefs loop so a
+-- saved entry for its connector still carries the mode/scale/position, while
+-- this rule holds the shipped defaults and the panel-specific color policy.
+local shipped_mode = "4500x3000@60"
+local shipped_scale = 1.5
+local shipped_transform = 0
+local kuycon = display_entry("DP-2")
+hl.monitor({
+    output   = "desc:GVT Kuycon P20",
+    mode     = kuycon and kuycon.mode or shipped_mode,
+    position = display_position(kuycon, "0x0"),
+    scale    = kuycon and kuycon.scale or shipped_scale,
+    transform = kuycon and kuycon.transform or shipped_transform,
+
+    -- 10-bit output. 4500x3000@60 at 10bpc is ~24 Gbps, right at the edge of
+    -- DP 1.4 HBR3, so this relies on DSC. If the display fails to light up or
+    -- falls back to a lower mode, drop this line first.
+    bitdepth = 10,
+
+    -- "auto" = sRGB at 8bpc, wide gamut at 10bpc. Not HDR; see header.
+    cm = "auto",
+})
 
 -- Any monitor not named above: sane defaults rather than nothing.
 hl.monitor({

tests/quickshell/displays-contract

@@ -122,8 +122,14 @@ assert(by_output["DP-2"].mode == "4500x3000@60")
 assert(by_output["DP-2"].scale == 1.5)
 assert(by_output["DP-2"].transform == 0)
 assert(by_output["DP-2"].position == "0x0")
-assert(by_output["DP-2"].bitdepth == 10)
+-- The panel-specific color policy rides the description-matched rule, not the
-assert(by_output["DP-2"].cm == "auto")
+-- connector: a stranger's monitor on DP-2 must not inherit the Kuycon's mode
+-- or its 10-bit request.
+local kuycon = by_output["desc:GVT Kuycon P20"]
+assert(kuycon ~= nil)
+assert(kuycon.mode == "4500x3000@60")
+assert(kuycon.bitdepth == 10)
+assert(kuycon.cm == "auto")
 assert(by_output["HDMI-A-1"].mode == "2560x1440@60")
 assert(by_output["HDMI-A-1"].scale == 1)
 assert(by_output["HDMI-A-1"].transform == 1)