Fix GitHub Release note extraction

Author: monarchjuno

.github/workflows/release.yml

@@ -228,7 +228,7 @@ jobs:
           version = re.escape(os.environ["RELEASE_VERSION"])
           changelog = Path("CHANGELOG.md").read_text(encoding="utf-8")
           match = re.search(
-              rf"^## {version} - .*$\n.*?(?=^## |\Z)",
+              rf"^## {version} - [^\n]*$\n.*?(?=^## |\Z)",
               changelog,
               flags=re.MULTILINE | re.DOTALL,
           )

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- Stop automated GitHub Release notes at the next changelog heading so a
+  release contains only its matching version section.
+
 ## 1.2.1 - 2026-07-21
 
 - Create or refresh the GitHub Release from the exact verified distributions

tests/test_release_contract.py

@@ -711,6 +711,7 @@ def test_release_publish_is_tag_bound_and_reuses_one_verified_build() -> None:
     assert any("download-artifact" in step.get("uses", "") for step in github_release["steps"])
     assert "CHANGELOG.md" in release_job_steps
     assert "release-notes.md" in release_job_steps
+    assert ' - [^\\n]*$\\n.*?(?=^## |\\Z)' in release_job_steps
     assert "gh release create" in release_job_steps
     assert "gh release edit" in release_job_steps
     assert "gh release upload" in release_job_steps