🐛 FIX: texmath infinite loop on block math closed outside blockquote

[acaprino]

Fixes #156.

make_block_func in texmath/index.py matched each block rule's regex against the rest of the source, so a block opened inside a blockquote could match a closing delimiter placed after it. The rule then pushed a token and returned True without advancing state.line, and the block tokenizer looped forever:

MarkdownIt("commonmark").use(texmath_plugin).parse("> $$ a=1\n\n$$\n")  # never returned

Change

• The closing line is searched only within [begLine, endLine). If the match ends outside the current block, the rule returns False before pushing any token. It does not auto-close, which is how amsmath behaves since Infinite loop in amsmath extension for a simple input #117. The example above now renders $$ a=1 as a paragraph in the blockquote, followed by $$ as a paragraph.
• When the closing line is inside the block, nothing changes: the same line is found and the token is identical.

Tests

• Fixtures in texmath_dollar.md and texmath_bracket.md: blockquote, and blockquote inside a list item.
• test_block_closed_outside_blockquote, one case per delimiter set (brackets, dollars, kramdown, gitlab, julia). Without the fix these tests hit the pytest timeout.
• Full suite passes locally (519 tests), along with ruff check, ruff format --check and mypy mdit_py_plugins.

The CHANGELOG.md entry opens an Unreleased section, like #148 does, so the two PRs will conflict trivially there.

🤖 Generated with Claude Code

https://claude.ai/code/session_01UQqBAyRu8anrLPy829yMmV