test(theme-studio): extract color/slug helpers to importable modules and cover them

The pure helpers that were still stranded in app.js — normHex, ratingColor, textOn, and the filename-slug logic — had no unit tests because app.js can't be imported (it runs its bootstrap and references the data placeholders at load). Moved them into importable modules so they can be tested directly: a new app-util.js holds the color/UI-boundary trio, and slugify joins app-core.js. app.js keeps thin wrappers, so no call site changed and the built DOM is byte-identical.

textOn needs rl from colormath, so generate.py's inline strip now drops import lines as well as export lines — app-util.js imports rl for its tests, and the import is stripped on inline where rl is already in the page. _faces in generate.py also gets direct tests for its prefix-strip and label derivation.

New: 12 node tests (normHex, ratingColor, textOn, slugify) and 7 python tests (_faces, app-util integrity, the import strip). Coverage: app-util.js 100/100/100, app-core.js 100/94.9/100, colormath.js 100/96/100 (line/branch/func); generate.py 89% lines (the rest is the __main__ writer and the optional seed-env branch). No bugs surfaced — the logic was correct, just untested.

1 files changed, 20 insertions, 0 deletions

diff --git a/scripts/theme-studio/app-util.js b/scripts/theme-studio/app-util.js
new file mode 100644
index 00000000..e3f76dd8
--- /dev/null
+++ b/scripts/theme-studio/app-util.js
@@ -0,0 +1,20 @@
+// Pure color/UI-boundary helpers: hex-input parsing, the contrast-rating status
+// color, and the readable text color for a background. These are kept out of
+// colormath.js (the pure math core) but are unit-tested and inlined into the page
+// the same way. textOn leans on rl from colormath; the import is for the tests —
+// generate.py strips it on inline, where rl is already present from the inlined
+// colormath core.
+import { rl } from './colormath.js';
+
+// Normalize a hex string: trim, accept an optional leading #, require exactly six
+// hex digits, lowercase the result. Returns null for anything else.
+function normHex(s){s=s.trim();if(/^[0-9a-fA-F]{6}$/.test(s))s='#'+s;return /^#[0-9a-fA-F]{6}$/.test(s)?s.toLowerCase():null;}
+
+// Map a WCAG contrast ratio to a status color: AAA green (>=7), AA grey (>=4.5),
+// otherwise the fail red.
+function ratingColor(r){return r>=7?'#5d9b86':r>=4.5?'#a9b2bb':'#cb6b4d';}
+
+// Pick black or white text for a background hex, by WCAG relative luminance.
+function textOn(h){const L=rl(h);return ((L+0.05)/0.05)>(1.05/(L+0.05))?'#000':'#fff';}
+
+export { normHex, ratingColor, textOn };