fix: theme KDE Frameworks apps off Plasma

kcalc rendered white under the dark Kvantum theme. Off Plasma,
KStyleManager forces Breeze unless kdeglobals names a widgetStyle, and
KColorSchemeManager applies BreezeLight unless kdeglobals names a colour
scheme; qt6ct never forwards the portal's prefer-dark to Qt.

Generate a udt.colors KColorScheme from the Kvantum roles, install it to
~/.local/share/color-schemes/, and point kdeglobals at it and at
kvantum-dark.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

4 files changed, 64 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index e19c1d7..e37b5b6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,6 +15,7 @@ __pycache__/
 /bin/udt_colors.py
 /templates/kvantum/theme.kvconfig
 /templates/kvantum/theme.svg
+/templates/kde/udt.colors
 /templates/obsidian/udt.css
 /templates/gtk/gtk3.css
 /templates/gtk/gtk4.css
diff --git a/AGENTS.md b/AGENTS.md
index 490932d..35fde22 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -41,7 +41,7 @@ switch into a diff. Editing one is pointless: the next install overwrites it.
 The generated set is `rofi/udt/palette.rasi`,
 `templates/conky.conf`, `templates/waybar/theme.css`,
 `templates/terminal/kitty-theme.conf`, `templates/homepage/custom.css`,
-`templates/kvantum/theme.{kvconfig,svg}`,
+`templates/kvantum/theme.{kvconfig,svg}`, `templates/kde/udt.colors`,
 `templates/sublime/udt.sublime-color-scheme`,
 `templates/sublime/udt.sublime-theme`, `templates/gtk/gtk{3,4}.css`,
 `templates/gtk/index.theme`, `templates/gtk/assets/*.svg`,
@@ -82,6 +82,13 @@ stylesheets and their 67 widget assets are now templates rendered into
 GTK4 symlink are set once. See `templates/gtk/README.md` for what is
 substituted and what is deliberately left as upstream drew it.
 
+**KDE Frameworks apps (kcalc etc.) skip qt6ct twice off Plasma.**
+`KStyleManager` forces Breeze unless kdeglobals `[KDE] widgetStyle` is set, and
+`KColorSchemeManager` applies BreezeLight unless `[UiSettings] ColorScheme`
+names a scheme; qt6ct never passes the portal's `prefer-dark` to Qt. Either
+alone left kcalc white. `install.sh` installs a generated `udt.colors` into
+`~/.local/share/color-schemes/` and sets both keys with `kwriteconfig6`.
+
 **Qt apps only read a theme at startup**, so a running one keeps the old
 colours until restarted. `install.sh` cannot signal them and does not try.
 
diff --git a/bin/udt-palette b/bin/udt-palette
index fbe53e6..04451f7 100755
--- a/bin/udt-palette
+++ b/bin/udt-palette
@@ -404,6 +404,49 @@ def gen_kvantum(res, scheme, palette, template):
     return out
 
 
+def gen_kde(res, scheme, palette):
+    """KDE Frameworks apps: a KColorScheme file, the same roles as Kvantum.
+
+    Off Plasma, KColorSchemeManager ignores the Qt style's palette and falls
+    back to BreezeLight unless kdeglobals names a scheme, which is how kcalc
+    ended up white under a dark Kvantum theme. install.sh points kdeglobals at
+    this file. Colours are r,g,b triplets; the accent is the scheme's own,
+    since these apps read it once at startup.
+    """
+    def rgb(role):
+        r, g, b, _ = res[role]
+        return f"{r},{g},{b}"
+
+    fg = {
+        "ForegroundNormal": "fg", "ForegroundInactive": "fg_dim",
+        "ForegroundActive": "accent", "ForegroundLink": "accent",
+        "ForegroundVisited": "accent_bright", "ForegroundNegative": "critical",
+        "ForegroundNeutral": "warning", "ForegroundPositive": "success",
+        "DecorationFocus": "accent", "DecorationHover": "accent",
+    }
+    sets = {
+        "Window": ("bg", "surface"),
+        "View": ("bg_alt", "bg"),
+        "Button": ("surface", "surface_alt"),
+        "Header": ("bg", "surface"),
+        "Tooltip": ("bg_alt", "surface"),
+        "Complementary": ("bg_alt", "surface"),
+        "Selection": ("accent", "accent_dim"),
+    }
+    out = [f"# {BANNER.format(scheme=scheme)}", "[General]",
+           "ColorScheme=udt", "Name=udt", ""]
+    for name, (bg, bg_alt) in sets.items():
+        roles = dict(fg, BackgroundNormal=bg, BackgroundAlternate=bg_alt)
+        if name == "Selection":
+            # Text on a solid accent fill, so it takes the dark end.
+            roles.update(ForegroundNormal="bg", ForegroundActive="bg",
+                         ForegroundInactive="surface")
+        out.append(f"[Colors:{name}]")
+        out += [f"{k}={rgb(v)}" for k, v in sorted(roles.items())]
+        out.append("")
+    return "\n".join(out)
+
+
 # Shades upstream computed from a palette colour rather than taking one. Each
 # paints exactly one widget surface, so leaving them literal (the rule that is
 # right for the neutral greys) left twelve lavender and Macchiato-tinted spots
@@ -700,6 +743,7 @@ TARGETS = [
     ("templates/typora/udt.css", gen_typora, "templates/typora/udt.css.in"),
     ("templates/kvantum/theme.kvconfig", gen_kvantum, "templates/kvantum/theme.kvconfig.in"),
     ("templates/kvantum/theme.svg", gen_kvantum, "templates/kvantum/theme.svg.in"),
+    ("templates/kde/udt.colors", gen_kde, None),
     ("templates/sublime/udt.sublime-color-scheme", gen_sublime,
      "templates/sublime/udt.sublime-color-scheme.in"),
     ("templates/sublime/udt.sublime-theme", gen_sublime_theme,
diff --git a/install.sh b/install.sh
index 7b68ad6..8a5755d 100755
--- a/install.sh
+++ b/install.sh
@@ -137,6 +137,17 @@ install -Dm644 "$repo/templates/kvantum/theme.kvconfig" "$kv/udt.kvconfig"
 install -Dm644 "$repo/templates/kvantum/theme.svg"      "$kv/udt.svg"
 printf '[General]\ntheme=udt\n' > "$HOME/.config/Kvantum/kvantum.kvconfig"
 
+# KDE Frameworks apps (kcalc and friends) bypass qt6ct twice over off Plasma:
+# KStyleManager forces Breeze unless kdeglobals names a widgetStyle, and
+# KColorSchemeManager applies BreezeLight unless kdeglobals names a scheme.
+# kdeglobals is edited in place, two keys only, like the gsettings calls below.
+install -Dm644 "$repo/templates/kde/udt.colors" \
+    "$HOME/.local/share/color-schemes/udt.colors"
+if command -v kwriteconfig6 >/dev/null 2>&1; then
+    kwriteconfig6 --file kdeglobals --group UiSettings --key ColorScheme udt
+    kwriteconfig6 --file kdeglobals --group KDE --key widgetStyle kvantum-dark
+fi
+
 # GTK3 and GTK4. Installed under one fixed name for every scheme, like Kvantum:
 # the theme name is set in gsettings and in a symlink, so a per-scheme name
 # would mean rewriting both on every switch and leaving stale themes behind.