Harden renderer CSS selector parsing in stylesheet tests

- Split selector lists on top-level commas to handle `:is(...)` safely
- Normalize selector whitespace before matching extracted CSS rule blocks
- Replace brittle full-file regex checks with targeted hover/selection block assertions
- Add TASK-114 backlog record for CI fix on PR #15

backlog/tasks/task-114 - Fix-failing-CI-checks-on-PR-15.md

@@ -0,0 +1,62 @@
+---
+id: TASK-114
+title: Fix failing CI checks on PR 15
+status: Done
+assignee:
+  - codex
+created_date: '2026-03-08 00:34'
+updated_date: '2026-03-08 00:37'
+labels:
+  - ci
+  - test
+dependencies: []
+references:
+  - src/renderer/subtitle-render.test.ts
+  - src/renderer/style.css
+  - .github/workflows/ci.yml
+priority: high
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Investigate the failing GitHub Actions CI run for PR #15 on branch `yomitan-fork`, fix the underlying test or code regression, and verify the affected local test/CI lane passes.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [x] #1 Identified the concrete failing CI job and captured the relevant failure context
+- [x] #2 Implemented the minimal code or test change needed to resolve the CI failure
+- [x] #3 Verified the affected local test target and the broader fast CI test lane pass
+<!-- AC:END -->
+
+## Implementation Plan
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Inspect the failing GitHub Actions run and confirm the exact failing test/assertion.
+2. Reproduce the failing renderer stylesheet test locally and compare the assertion against current CSS.
+3. Apply the minimal test or stylesheet fix needed to restore the intended hover/selection behavior.
+4. Re-run the targeted renderer test, then re-run `bun run test` to verify the fast CI lane is green.
+<!-- SECTION:PLAN:END -->
+
+## Implementation Notes
+
+<!-- SECTION:NOTES:BEGIN -->
+GitHub Actions run 22810400921 failed in job build-test-audit, step `Test suite (source)`, with a single failing test: `JLPT CSS rules use underline-only styling in renderer stylesheet` in src/renderer/subtitle-render.test.ts.
+
+Reproduced the failing test locally with `bun test src/renderer/subtitle-render.test.ts`. The failure was a brittle stylesheet assertion, not a renderer behavior regression.
+
+Updated the renderer stylesheet test helper to split selectors safely across `:is(...)` commas and normalize multiline selector whitespace, then switched the failing hover/JLPT assertions to inspect extracted rule blocks instead of matching the entire CSS file text.
+
+Verification passed with `bun test src/renderer/subtitle-render.test.ts` and `bun run test`.
+<!-- SECTION:NOTES:END -->
+
+## Final Summary
+
+<!-- SECTION:FINAL_SUMMARY:BEGIN -->
+Investigated GitHub Actions CI run `22810400921` for PR #15 and confirmed the only failing job was `build-test-audit`, step `Test suite (source)`, with a single failure in `src/renderer/subtitle-render.test.ts` (`JLPT CSS rules use underline-only styling in renderer stylesheet`).
+
+The renderer CSS itself was still correct; the regression was in the test helper. `extractClassBlock` was splitting selector lists on every comma, which breaks selectors containing `:is(...)`, and the affected assertions fell back to brittle whole-file regex matching against a multiline selector. Fixed the test by teaching the helper to split selectors only at top-level commas, normalizing selector whitespace around multiline `:not(...)` / `:is(...)` clauses, and asserting on extracted rule blocks for the plain-word hover and JLPT-only hover/selection rules.
+
+Verification: `bun test src/renderer/subtitle-render.test.ts` passed, and `bun run test` passed end to end (the same fast lane that failed in CI).
+<!-- SECTION:FINAL_SUMMARY:END -->

src/renderer/subtitle-render.test.ts

@@ -138,17 +138,15 @@ function extractClassBlock(cssText: string, selector: string): string {
   const ruleRegex = /([^{}]+)\{([^}]*)\}/g;
   let match: RegExpExecArray | null = null;
   let fallbackBlock = '';
+  const normalizedSelector = normalizeCssSelector(selector);
 
   while ((match = ruleRegex.exec(cssText)) !== null) {
     const selectorsBlock = match[1]?.trim() ?? '';
     const selectorBlock = match[2] ?? '';
 
-    const selectors = selectorsBlock
-      .split(',')
-      .map((entry) => entry.trim())
-      .filter((entry) => entry.length > 0);
+    const selectors = splitCssSelectors(selectorsBlock);
 
-    if (selectors.includes(selector)) {
+    if (selectors.some((entry) => normalizeCssSelector(entry) === normalizedSelector)) {
       if (selectors.length === 1) {
         return selectorBlock;
       }
@@ -166,6 +164,53 @@ function extractClassBlock(cssText: string, selector: string): string {
   return '';
 }
 
+function splitCssSelectors(selectorsBlock: string): string[] {
+  const selectors: string[] = [];
+  let current = '';
+  let parenDepth = 0;
+
+  for (const char of selectorsBlock) {
+    if (char === '(') {
+      parenDepth += 1;
+      current += char;
+      continue;
+    }
+
+    if (char === ')') {
+      parenDepth = Math.max(0, parenDepth - 1);
+      current += char;
+      continue;
+    }
+
+    if (char === ',' && parenDepth === 0) {
+      const trimmed = current.trim();
+      if (trimmed.length > 0) {
+        selectors.push(trimmed);
+      }
+      current = '';
+      continue;
+    }
+
+    current += char;
+  }
+
+  const trimmed = current.trim();
+  if (trimmed.length > 0) {
+    selectors.push(trimmed);
+  }
+
+  return selectors;
+}
+
+function normalizeCssSelector(selector: string): string {
+  return selector
+    .replace(/\s+/g, ' ')
+    .replace(/\(\s+/g, '(')
+    .replace(/\s+\)/g, ')')
+    .replace(/\s*,\s*/g, ', ')
+    .trim();
+}
+
 test('computeWordClass preserves known and n+1 classes while adding JLPT classes', () => {
   const knownJlpt = createToken({
     isKnown: true,
@@ -669,9 +714,21 @@ test('JLPT CSS rules use underline-only styling in renderer stylesheet', () => {
   );
   assert.match(jlptTooltipKeyboardSelectedBlock, /opacity:\s*1;/);
 
-  assert.match(
+  const plainWordHoverBlock = extractClassBlock(
     cssText,
-    /#subtitleRoot\s+\.word:not\(\.word-known\):not\(\.word-n-plus-one\):not\(\.word-name-match\):not\(\.word-frequency-single\):not\(\s*\.word-frequency-band-1\s*\):not\(\.word-frequency-band-2\):not\(\.word-frequency-band-3\):not\(\.word-frequency-band-4\):not\(\s*\.word-frequency-band-5\s*\):hover\s*\{[\s\S]*?background:\s*var\(--subtitle-hover-token-background-color,\s*rgba\(54,\s*58,\s*79,\s*0\.84\)\);[\s\S]*?color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;[\s\S]*?-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+    '#subtitleRoot .word:not(.word-known):not(.word-n-plus-one):not(.word-name-match):not(.word-frequency-single):not(.word-frequency-band-1):not(.word-frequency-band-2):not(.word-frequency-band-3):not(.word-frequency-band-4):not(.word-frequency-band-5):hover',
+  );
+  assert.match(
+    plainWordHoverBlock,
+    /background:\s*var\(--subtitle-hover-token-background-color,\s*rgba\(54,\s*58,\s*79,\s*0\.84\)\);/,
+  );
+  assert.match(
+    plainWordHoverBlock,
+    /color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+  );
+  assert.match(
+    plainWordHoverBlock,
+    /-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
   );
 
   const coloredWordHoverBlock = extractClassBlock(cssText, '#subtitleRoot .word.word-known:hover');
@@ -707,13 +764,31 @@ test('JLPT CSS rules use underline-only styling in renderer stylesheet', () => {
   assert.match(coloredCharHoverBlock, /background:\s*transparent;/);
   assert.match(coloredCharHoverBlock, /color:\s*inherit\s*!important;/);
 
-  assert.match(
+  const jlptOnlyHoverBlock = extractClassBlock(
     cssText,
-    /\.word:is\(\.word-jlpt-n1,\s*\.word-jlpt-n2,\s*\.word-jlpt-n3,\s*\.word-jlpt-n4,\s*\.word-jlpt-n5\):not\(\s*\.word-known\s*\):not\(\.word-n-plus-one\):not\(\.word-name-match\):not\(\.word-frequency-single\):not\(\.word-frequency-band-1\):not\(\s*\.word-frequency-band-2\s*\):not\(\.word-frequency-band-3\):not\(\.word-frequency-band-4\):not\(\.word-frequency-band-5\):hover\s*\{[\s\S]*?color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;[\s\S]*?-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+    '#subtitleRoot .word:is(.word-jlpt-n1, .word-jlpt-n2, .word-jlpt-n3, .word-jlpt-n4, .word-jlpt-n5):not(.word-known):not(.word-n-plus-one):not(.word-name-match):not(.word-frequency-single):not(.word-frequency-band-1):not(.word-frequency-band-2):not(.word-frequency-band-3):not(.word-frequency-band-4):not(.word-frequency-band-5):hover',
   );
   assert.match(
-    cssText,
-    /\.word:is\(\.word-jlpt-n1,\s*\.word-jlpt-n2,\s*\.word-jlpt-n3,\s*\.word-jlpt-n4,\s*\.word-jlpt-n5\):not\(\s*\.word-known\s*\):not\(\.word-n-plus-one\):not\(\.word-name-match\):not\(\.word-frequency-single\):not\(\.word-frequency-band-1\):not\(\s*\.word-frequency-band-2\s*\):not\(\.word-frequency-band-3\):not\(\.word-frequency-band-4\):not\(\.word-frequency-band-5\)::selection[\s\S]*?color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;[\s\S]*?-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+    jlptOnlyHoverBlock,
+    /color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+  );
+  assert.match(
+    jlptOnlyHoverBlock,
+    /-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+  );
+  assert.match(
+    extractClassBlock(
+      cssText,
+      '#subtitleRoot .word:is(.word-jlpt-n1, .word-jlpt-n2, .word-jlpt-n3, .word-jlpt-n4, .word-jlpt-n5):not(.word-known):not(.word-n-plus-one):not(.word-name-match):not(.word-frequency-single):not(.word-frequency-band-1):not(.word-frequency-band-2):not(.word-frequency-band-3):not(.word-frequency-band-4):not(.word-frequency-band-5)::selection',
+    ),
+    /color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
+  );
+  assert.match(
+    extractClassBlock(
+      cssText,
+      '#subtitleRoot .word:is(.word-jlpt-n1, .word-jlpt-n2, .word-jlpt-n3, .word-jlpt-n4, .word-jlpt-n5):not(.word-known):not(.word-n-plus-one):not(.word-name-match):not(.word-frequency-single):not(.word-frequency-band-1):not(.word-frequency-band-2):not(.word-frequency-band-3):not(.word-frequency-band-4):not(.word-frequency-band-5)::selection',
+    ),
+    /-webkit-text-fill-color:\s*var\(--subtitle-hover-token-color,\s*#f4dbd6\)\s*!important;/,
   );
 
   const selectionBlock = extractClassBlock(cssText, '#subtitleRoot::selection');