refactor(theme-studio): share oklchOf and isPureEndpointHex from colormath

oklchOf and isPureEndpointHex were each defined identically in app-core.js and palette-generator-core.js, and hueOfHex inlined oklchOf's body a third time. I moved both helpers into colormath.js, which already owns the primitives they call, and had the two consumers import them. hueOfHex now calls oklchOf instead of re-deriving it.

4 files changed, 15 insertions, 13 deletions

diff --git a/scripts/theme-studio/app-core.js b/scripts/theme-studio/app-core.js
index 1f2ee9d91..9780a7820 100644
--- a/scripts/theme-studio/app-core.js
+++ b/scripts/theme-studio/app-core.js
@@ -9,7 +9,7 @@
 // where normHex (app-util.js) and the colormath helpers are already present from
 // the bodies inlined above this one.
 import { normHex } from './app-util.js';
-import { oklch2hex, srgb2oklab, oklab2oklch, oklab2lrgb, lrgb2hex, inGamut, contrast } from './colormath.js';
+import { oklch2hex, srgb2oklab, oklab2lrgb, lrgb2hex, inGamut, contrast, oklchOf, isPureEndpointHex } from './colormath.js';
 
 // Resolve a palette name (or a raw #hex) to a hex; null when the name is unknown.
 function nameToHex(n,palette){if(!n)return null;if(/^#/.test(n))return n;const p=palette.find(p=>p[1]===n);return p?p[0]:null;}
@@ -204,9 +204,7 @@ function lMax(hue,chroma,fgSet,target){
 // the editable truth; these pure functions group it, regenerate a ramp, and plan
 // assignment re-point across a regenerate.
 
-function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
 function isReservedGroundLikeName(name){return /^(bg|fg)(?:[-_+].+|\d.*)$/i.test(name||'');}
-function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
 function interpOklabHex(a,b,t,offset){
   const lab={L:a.L+(b.L-a.L)*t,a:a.a+(b.a-a.a)*t,b:a.b+(b.b-a.b)*t};
   const lrgb=oklab2lrgb(lab.L,lab.a,lab.b);
diff --git a/scripts/theme-studio/colormath.js b/scripts/theme-studio/colormath.js
index 2a7328e54..b57da9131 100644
--- a/scripts/theme-studio/colormath.js
+++ b/scripts/theme-studio/colormath.js
@@ -217,4 +217,9 @@ function reliefColors(bgHex) {
   return { hl: one(1.2, 0x8000), sh: one(0.6, 0x4000) };
 }
 
-export { srgb2oklab, oklab2oklch, oklch2oklab, oklch2hex, apca, deltaE, hex2rgb, lin, rl, contrast, rating, hsv2rgb, rgb2hsv, rgb2hex, oklab2lrgb, inGamut, lrgb2hex, planeCell, paletteWarnings, reliefColors };
+// OKLCH of a hex, and the pure black/white endpoint test. Shared by app-core
+// and palette-generator-core (both previously kept their own identical copies).
+function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
+function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
+
+export { srgb2oklab, oklab2oklch, oklch2oklab, oklch2hex, apca, deltaE, hex2rgb, lin, rl, contrast, rating, hsv2rgb, rgb2hsv, rgb2hex, oklab2lrgb, inGamut, lrgb2hex, planeCell, paletteWarnings, reliefColors, oklchOf, isPureEndpointHex };
diff --git a/scripts/theme-studio/palette-generator-core.js b/scripts/theme-studio/palette-generator-core.js
index 6bce0d59a..94ed38011 100644
--- a/scripts/theme-studio/palette-generator-core.js
+++ b/scripts/theme-studio/palette-generator-core.js
@@ -2,11 +2,9 @@
 // from app-core.js, but owns candidate hue selection, naming, contrast filtering,
 // and conversion from preview columns to palette entries.
 import { normHex } from './app-util.js';
-import { oklch2hex, srgb2oklab, oklab2oklch, contrast, deltaE } from './colormath.js';
+import { oklch2hex, contrast, deltaE, oklchOf, isPureEndpointHex } from './colormath.js';
 import { columnsFromPalette } from './app-core.js';
 
-function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
-function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
 function generatedExistingNames(palette){
   return new Set((palette||[]).map(p=>(p&&p[1]||'').toLowerCase()).filter(Boolean));
 }
@@ -27,7 +25,7 @@ function uniqueGeneratedName(base,used){
 function hueOfHex(hex,fallback){
   const h=typeof hex==='string'?normHex(hex):null;
   if(!h)return fallback;
-  const lch=oklab2oklch(srgb2oklab(h));
+  const lch=oklchOf(h);
   return Number.isFinite(lch.H)?lch.H:fallback;
 }
 function generatorSourceHue(palette,ground,cfg){
diff --git a/scripts/theme-studio/theme-studio.html b/scripts/theme-studio/theme-studio.html
index 4d2c51fc1..a3a5468cb 100644
--- a/scripts/theme-studio/theme-studio.html
+++ b/scripts/theme-studio/theme-studio.html
@@ -523,6 +523,11 @@ function reliefColors(bgHex) {
   };
   return { hl: one(1.2, 0x8000), sh: one(0.6, 0x4000) };
 }
+
+// OKLCH of a hex, and the pure black/white endpoint test. Shared by app-core
+// and palette-generator-core (both previously kept their own identical copies).
+function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
+function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
 // Pure package-model + dropdown logic, inlined verbatim from app-core.js. The
 // wrappers above (pname/seedPkgmap/ddList/pkgEffFg/pkgEffBg) delegate here.
 // Pure app logic — the package-face model and the dropdown option list — with no
@@ -729,9 +734,7 @@ function lMax(hue,chroma,fgSet,target){
 // the editable truth; these pure functions group it, regenerate a ramp, and plan
 // assignment re-point across a regenerate.
 
-function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
 function isReservedGroundLikeName(name){return /^(bg|fg)(?:[-_+].+|\d.*)$/i.test(name||'');}
-function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
 function interpOklabHex(a,b,t,offset){
   const lab={L:a.L+(b.L-a.L)*t,a:a.a+(b.a-a.a)*t,b:a.b+(b.b-a.b)*t};
   const lrgb=oklab2lrgb(lab.L,lab.a,lab.b);
@@ -1069,8 +1072,6 @@ function contrastTitle(r){
 // from app-core.js, but owns candidate hue selection, naming, contrast filtering,
 // and conversion from preview columns to palette entries.
 
-function oklchOf(hex){return oklab2oklch(srgb2oklab(hex));}
-function isPureEndpointHex(hex){const h=(hex||'').toLowerCase();return h==='#ffffff'||h==='#000000';}
 function generatedExistingNames(palette){
   return new Set((palette||[]).map(p=>(p&&p[1]||'').toLowerCase()).filter(Boolean));
 }
@@ -1091,7 +1092,7 @@ function uniqueGeneratedName(base,used){
 function hueOfHex(hex,fallback){
   const h=typeof hex==='string'?normHex(hex):null;
   if(!h)return fallback;
-  const lch=oklab2oklch(srgb2oklab(h));
+  const lch=oklchOf(h);
   return Number.isFinite(lch.H)?lch.H:fallback;
 }
 function generatorSourceHue(palette,ground,cfg){