From 10035593e3973d57355a827c55bd6bb5553bab37 Mon Sep 17 00:00:00 2001
From: Yuzhong Zhang <BetterAndBetterII@users.noreply.github.com>
Date: Sat, 29 Aug 2026 19:35:07 +0000
Subject: [PATCH] fix: strip nested prefixes from multi-line dollarmath blocks

Fixes #125
---
 mdit_py_plugins/dollarmath/index.py | 18 +++++++++++++++-
 tests/fixtures/dollar_math.md       | 33 +++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/mdit_py_plugins/dollarmath/index.py b/mdit_py_plugins/dollarmath/index.py
index 57ba590..e24b050 100644
--- a/mdit_py_plugins/dollarmath/index.py
+++ b/mdit_py_plugins/dollarmath/index.py
@@ -287,6 +287,22 @@ def _math_inline_dollar(state: StateInline, silent: bool) -> bool:
 DOLLAR_EQNO_REV = re.compile(r"^\s*\)([^)$\r\n]+?)\(\s*\${2}")
 
 
+def _math_block_content(
+    state: StateBlock, startLine: int, startPos: int, endLine: int, end: int
+) -> str:
+    """Extract math body, omitting parent container prefixes on each line."""
+    content_start = startPos + 2
+    if startLine == endLine:
+        return state.src[content_start:end]
+
+    parts: list[str] = [state.src[content_start : state.eMarks[startLine]], "\n"]
+    for line in range(startLine + 1, endLine):
+        parts.append(state.src[state.bMarks[line] : state.eMarks[line]])
+        parts.append("\n")
+    parts.append(state.src[state.bMarks[endLine] : end])
+    return "".join(parts)
+
+
 def math_block_dollar(
     allow_labels: bool = True,
     label_normalizer: Callable[[str], str] | None = None,
@@ -365,7 +381,7 @@ def _math_block_dollar(
 
         token = state.push("math_block_label" if label else "math_block", "math", 0)
         token.block = True
-        token.content = state.src[startPos + 2 : end]
+        token.content = _math_block_content(state, startLine, startPos, nextLine, end)
         token.markup = "$$"
         token.map = [startLine, state.line]
         if label:
diff --git a/tests/fixtures/dollar_math.md b/tests/fixtures/dollar_math.md
index 08a2e90..d4421d8 100644
--- a/tests/fixtures/dollar_math.md
+++ b/tests/fixtures/dollar_math.md
@@ -418,6 +418,39 @@ a+b=c
 </blockquote>
 .
 
+display equation in blockquote, multi-line. (valid=True)
+.
+> Given
+>
+> $$
+> x^2 + y^2 = 9
+> $$
+>
+> What is the radius of the circle?
+.
+<blockquote>
+<p>Given</p>
+<div class="math block">
+x^2 + y^2 = 9
+</div>
+<p>What is the radius of the circle?</p>
+</blockquote>
+.
+
+labelled display equation in blockquote, multi-line. (valid=True)
+.
+> $$
+> a+b=c
+> $$ (2)
+.
+<blockquote>
+<div id="2" class="math block">
+<a href="#2" class="mathlabel" title="Permalink to this equation">¶</a>
+a+b=c
+</div>
+</blockquote>
+.
+
 mixed syntax:
 .
 $$