fix(gtk): derive the twelve computed tints from the palette too

Twelve hexes were shades upstream computed from a palette colour rather than
taking one. They were left literal on the same reasoning as the neutral greys,
which was wrong: a grey is shading, but each of these paints one widget
surface in a colour that is supposed to be the theme's. Under any scheme but
Macchiato they stayed Macchiato, including the window close, minimise and
maximise hover fills.

They are substituted as @ROLE_PCT@ now, the percentage being that shade's
brightness relative to its base. shade() scales each channel and clamps, so it
keeps the relationship rather than the exact upstream value; closest on the
accent family, crudest on the reds, where upstream darkened toward saturation.

GTK4 carries ten of the twelve: the selected progress bar and the
selection-mode titlebar backdrop are GTK3-only widgets upstream.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/bin/udt-palette b/bin/udt-palette
index a9aa005..95b9092 100755
--- a/bin/udt-palette
+++ b/bin/udt-palette
@@ -368,6 +368,38 @@ def gen_kvantum(res, scheme, palette, template):
     return 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
+# on every other scheme: the window close/min/max hover fills among them.
+#
+# The percentage is that shade's brightness relative to its base, measured off
+# the Macchiato theme these were derived from. Reproducing the exact upstream
+# value is not the goal; keeping the relationship is.
+GTK_TINTS = [
+    ("@ACCENT_93@", "accent", 93),
+    ("@ACCENT_103@", "accent", 103),
+    ("@ACCENT_109@", "accent", 109),
+    ("@ACCENT_118@", "accent", 118),
+    ("@CRITICAL_110@", "critical", 110),
+    ("@CRITICAL_92@", "critical", 92),
+    ("@CRITICAL_79@", "critical", 79),
+    ("@WARNING_105@", "warning", 105),
+    ("@WARNING_94@", "warning", 94),
+    ("@WARNING_86@", "warning", 86),
+    ("@SUCCESS_109@", "success", 109),
+    ("@SUCCESS_81@", "success", 81),
+]
+
+
+def shade(c, pct):
+    """Scale a colour's channels by pct, clamped to 0-255."""
+    r, g, b, a = c
+    return (min(255, round(r * pct / 100)),
+            min(255, round(g * pct / 100)),
+            min(255, round(b * pct / 100)), a)
+
+
 def gen_gtk(res, scheme, palette, template):
     """GTK3/GTK4: substitute the palette into the upstream stylesheet.
 
@@ -380,6 +412,10 @@ def gen_gtk(res, scheme, palette, template):
     exactly as drawn, the same rule the Kvantum SVG follows.
     """
     out = template
+    # Tints first: @ACCENT_93@ starts with @ACCENT, so the plain role loop
+    # below would otherwise replace that prefix and leave a stray "_93@".
+    for placeholder, role, pct in GTK_TINTS:
+        out = out.replace(placeholder, hex6(shade(res[role], pct)))
     for role in GTK_ROLES:
         # _RGB@ first: @FG@ is a prefix of @FG_RGB@, so the bare form would
         # otherwise eat the start of the triple placeholder and leave "_RGB@".
@@ -732,6 +768,7 @@ def selftest():
     gtk_dir = REPO / "templates" / "gtk"
     known = {f"@{r.upper()}@" for r in GTK_ROLES}
     known |= {f"@{r.upper()}_RGB@" for r in GTK_ROLES}
+    known |= {placeholder for placeholder, _, _ in GTK_TINTS}
     known.add("@MAUVE@")
     for tpl in sorted(gtk_dir.glob("*.in")) + sorted((gtk_dir / "assets").glob("*.in")):
         used = set(re.findall(r"@[A-Z][A-Z_]*@", tpl.read_text()))