Task 132: 数式レンダリングのTDD回帰テスト

Status: DONE

Human Directive

「たまに数式のレンダリングが壊れている。TDD で修正することで維持するべき。」

Scope

1. Identify current math rendering failures (audit all reports for broken $...Identify current math rendering failures (audit all reports for broken and $...$`)
2. Add comprehensive regression tests for extractMath() and markdownToHtml() math handling
3. Test edge cases: nested delimiters, escaped dollars, math inside code blocks, adjacent math
4. Fix any currently broken math rendering
5. ~~Add E2E (Playwright) tests that verify KaTeX renders correctly in the browser~~ (deferred — unit tests cover the critical HTML output)

Bugs Found and Fixed

Bug 1: `Bug 1: inside backtick code captured as math delimiter

• Symptom: Use \$variable\CSLOT1 would match CSLOT2 in your code and $` as one math expression, breaking both the inline code and the subsequent math
• Root cause: extractMath() ran before inline code processing, so Root cause: extractMath()` ran before inline code processing, so inside backticks was treated as a math delimiter
• Fix: In extractMath(), temporarily protect backtick-delimited code with placeholders before running math regex, then restore backtick content afterward

Bug 2: Multi-line display math broken

• Symptom: $\n\\Delta V = \\sqrt{2}\n$ rendered as three separate <p> tags instead of a display math block
• Root cause: markdownToHtml() only handled single-line $...$ — multi-line display math (where $ opens and closes on separate lines) was not supported
• Fix: Added multi-line display math handling in markdownToHtml() that collects lines between $ delimiters and joins them into a single <p>$...$</p> block

Tests Added (16 new regression tests)

1. Trailing-space math (`$expr = Trailing-space math ()
2. Adjacent math-then-bold ($\\Delta V$比: ... $= $ bold)
3. Sequential `$= Sequential patterns without cross-matching
4. Nested \\frac{}{} braces
5. \\sqrt{} with parentheses
6. Thousands separator {,}
7. \\text{} command
8. Complex display math
9. Multiple display math blocks separated by text
10. Multi-line display math ($\n...\n$)
11. ` in inline code vs math
12. Math adjacent to Japanese text
13. Subscript/superscript notation
14. Inequality operators (<, >) not HTML-escaped in math
15. HTML escaping verification for math content
16. Aligned environment in display math

Test Results

• Templates tests: 383 pass, 0 fail (was 367 + 16 new)
• Full TS suite: 1271 pass, 19 fail (WASM build-dependent, pre-existing)
• TypeScript typecheck: clean
• Site build: successful

Dependencies

• Task 052 (KaTeX integration — DONE)