Release v1.2.1

- Update version to 1.2.1
- Add CHANGELOG entry for v1.2.1
- Add detailed release notes in docs/source/releases/v1.2.1.md
- Update releases index

This patch release fixes a ValueError when building LaTeX/PDF output
where 'std-ref' class may not be present in inline node classes.

Author: mmcky

CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## [v1.2.1](https://github.com/executablebooks/sphinx-exercise/tree/v1.2.1) (2025-11-17)
+
+### Fixes 🐛
+
+- Fixed `ValueError: list.remove(x): x not in list` when building LaTeX/PDF output ([#82](https://github.com/executablebooks/sphinx-exercise/pull/82))
+  - Added defensive check before removing 'std-ref' class in `UpdateReferencesToEnumerated` transform
+  - The 'std-ref' class may not be present in all build scenarios (particularly LaTeX/PDF builds)
+  - Fix ensures compatibility across different Sphinx builders and versions
+
 ## [v1.2.0](https://github.com/executablebooks/sphinx-exercise/tree/v1.2.0) (2025-11-05)
 
 ### New ✨

docs/source/releases/index.md

@@ -5,6 +5,7 @@ This section contains detailed release notes for sphinx-exercise versions.
 ```{toctree}
 :maxdepth: 1
 
+v1.2.1
 v1.2.0
 v1.1.1
 v1.1.0

docs/source/releases/v1.2.1.md

@@ -0,0 +1,65 @@
+# Release v1.2.1
+
+**Release Date**: November 17, 2025
+
+This is a patch release that fixes a bug causing build failures in LaTeX/PDF output.
+
+## 🐛 Bug Fixes
+
+### LaTeX/PDF Build Failure
+
+Fixed a `ValueError: list.remove(x): x not in list` error that occurred when building LaTeX/PDF documentation with sphinx-exercise v1.2.0.
+
+**Issue:**
+- The `UpdateReferencesToEnumerated` transform attempted to remove the `'std-ref'` CSS class from inline reference nodes
+- In LaTeX/PDF builds (and potentially other build scenarios), this class may not be present
+- Python's `list.remove()` raises a `ValueError` when the item doesn't exist, causing the build to fail
+
+**Fix:**
+- Added a defensive check: `if "std-ref" in classes:` before attempting removal
+- The transform now safely handles cases where the class is absent
+- Preserves the intended behavior: converting textual references to numeric references for enumerated exercises
+
+**Impact:**
+- Fixes build failures in projects using sphinx-exercise with LaTeX/PDF output
+- No functional changes to existing behavior
+- All existing tests continue to pass
+
+**Example Error (before fix):**
+```
+Exception occurred:
+  File ".../sphinx_exercise/post_transforms.py", line 69, in run
+    classes.remove("std-ref")
+ValueError: list.remove(x): x not in list
+```
+
+## 📦 Installation
+
+Install or upgrade via pip:
+
+```bash
+pip install --upgrade sphinx-exercise
+```
+
+## 🔄 Migration Notes
+
+**If you're upgrading from v1.2.0:**
+- No breaking changes
+- No action required
+- If you encountered LaTeX/PDF build failures with v1.2.0, this release fixes that issue
+
+**Compatibility:**
+- Python 3.10, 3.11, 3.12, 3.13
+- Sphinx 6, 7, 8
+- All existing directives and configurations continue to work
+
+## 🔗 Related Issues
+
+- PR [#82](https://github.com/executablebooks/sphinx-exercise/pull/82) - Fix std-ref class removal
+- Issue discovered in [QuantEcon/continuous_time_mcs CI build](https://github.com/QuantEcon/continuous_time_mcs/actions/runs/19413054039/job/55537214078?pr=144)
+
+## 📚 Documentation
+
+For complete documentation, see:
+- [Configuration Options](../syntax.md)
+- [Installation Guide](../install.md)

sphinx_exercise/__init__.py

@@ -7,7 +7,7 @@
 :license: MIT, see LICENSE for details.
 """
 
-__version__ = "1.2.0"
+__version__ = "1.2.1"
 
 from pathlib import Path
 from typing import Any, Dict, Set, Union, cast