From 6cb3105805089db1d6c25f49c832d9708516fa0c Mon Sep 17 00:00:00 2001
From: Neil Vaytet <neil.vaytet@ess.eu>
Date: Fri, 31 Jul 2026 12:13:26 +0200
Subject: [PATCH 1/3] monkeypatch _mathtext.Parser.parse() with a
 threading.Lock()

---
 src/plopp/__init__.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/plopp/__init__.py b/src/plopp/__init__.py
index 6e84745c..c385659b 100644
--- a/src/plopp/__init__.py
+++ b/src/plopp/__init__.py
@@ -44,4 +44,29 @@
 
 backends = BackendManager()
 
+# Workaround for thread-safety issues in matplotlib's mathtext parser.
+# The _mathtext.Parser singleton has mutable state (_state_stack, etc.) that is
+# not protected against concurrent access from multiple threads. When ipympl is
+# used with ipykernel >= 7 (which introduces additional threads for message
+# routing), concurrent calls to the parser can corrupt this state, leading to
+# ParseException errors like 'Expected end of text, found "$"'.
+# See https://github.com/matplotlib/ipympl/issues/610
+try:
+    import functools
+    from threading import Lock
+
+    from matplotlib._mathtext import Parser as _MathTextInternalParser
+
+    _mathtext_parse_lock = Lock()
+    _original_mathtext_parse = _MathTextInternalParser.parse
+
+    @functools.wraps(_original_mathtext_parse)
+    def _thread_safe_mathtext_parse(self, *args, **kwargs):
+        with _mathtext_parse_lock:
+            return _original_mathtext_parse(self, *args, **kwargs)
+
+    _MathTextInternalParser.parse = _thread_safe_mathtext_parse
+except Exception:
+    pass
+
 del importlib

From d65f3c5c193cfdac8ad8b9523f4ab59f7894bca4 Mon Sep 17 00:00:00 2001
From: Neil Vaytet <neil.vaytet@ess.eu>
Date: Fri, 31 Jul 2026 12:25:36 +0200
Subject: [PATCH 2/3] cleanup after monkeypatch

---
 src/plopp/__init__.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/plopp/__init__.py b/src/plopp/__init__.py
index c385659b..50747d6e 100644
--- a/src/plopp/__init__.py
+++ b/src/plopp/__init__.py
@@ -66,6 +66,8 @@ def _thread_safe_mathtext_parse(self, *args, **kwargs):
             return _original_mathtext_parse(self, *args, **kwargs)
 
     _MathTextInternalParser.parse = _thread_safe_mathtext_parse
+
+    del functools, Lock
 except Exception:
     pass
 

From c9066b84ecf2885cc1de90707c6055172a1b06c5 Mon Sep 17 00:00:00 2001
From: Neil Vaytet <neil.vaytet@ess.eu>
Date: Fri, 31 Jul 2026 12:27:26 +0200
Subject: [PATCH 3/3] ruff happy

---
 src/plopp/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plopp/__init__.py b/src/plopp/__init__.py
index 50747d6e..57a53f09 100644
--- a/src/plopp/__init__.py
+++ b/src/plopp/__init__.py
@@ -68,7 +68,7 @@ def _thread_safe_mathtext_parse(self, *args, **kwargs):
     _MathTextInternalParser.parse = _thread_safe_mathtext_parse
 
     del functools, Lock
-except Exception:
+except Exception:  # noqa: S110
     pass
 
 del importlib