From 53a6dfb72702f9ad0427bb55d57893c53508ed8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bern=C3=A1t=20G=C3=A1bor?= <gaborjbernat@gmail.com>
Date: Mon, 2 Nov 2026 16:54:10 -0800
Subject: [PATCH 1/2] =?UTF-8?q?=F0=9F=90=9B=20fix(spec):=20exclude=20bound?=
 =?UTF-8?q?ary=20prereleases?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/python_discovery/_specifier.py | 8 ++++++++
 tests/test_py_info_extra.py        | 1 +
 tests/test_specifier.py            | 5 +++++
 3 files changed, 14 insertions(+)

diff --git a/src/python_discovery/_specifier.py b/src/python_discovery/_specifier.py
index f9f05ea..89ce8cd 100644
--- a/src/python_discovery/_specifier.py
+++ b/src/python_discovery/_specifier.py
@@ -210,6 +210,14 @@ def _check_standard(self, candidate: SimpleVersion) -> bool:
             return str(candidate) == str(self.version)
         if self.operator == "~=":
             return self._check_compatible_release(candidate)
+        # PEP 440 excludes prereleases of a final release named by an exclusive upper bound.
+        if (
+            self.operator == "<"
+            and candidate.pre_type is not None
+            and self.version.pre_type is None
+            and candidate.release == self.version.release
+        ):
+            return False
         cmp_ops = {
             "==": operator.eq,
             "!=": operator.ne,
diff --git a/tests/test_py_info_extra.py b/tests/test_py_info_extra.py
index 016636a..f48b7d2 100644
--- a/tests/test_py_info_extra.py
+++ b/tests/test_py_info_extra.py
@@ -239,6 +239,7 @@ def test_satisfies_version_specifier_unparsable_version() -> None:
         pytest.param(VersionInfo(3, 15, 0, "alpha", 6), ">=3.15.0", False, id="prerelease_not_match_full_precision"),
         pytest.param(VersionInfo(3, 15, 0, "alpha", 5), "<3.15.0a6", True, id="earlier_prerelease_less_than"),
         pytest.param(VersionInfo(3, 15, 0, "alpha", 6), "<3.15.0a6", False, id="prerelease_not_less_than_itself"),
+        pytest.param(VersionInfo(3, 12, 0, "candidate", 1), "<3.12.0", False, id="prerelease_not_below_final_bound"),
         pytest.param(VersionInfo(3, 15, 0, "alpha", 6), ">=3.15.0a6", True, id="prerelease_match_itself"),
         pytest.param(VersionInfo(3, 15, 0, "alpha", 6), ">=3.15.0a7", False, id="prerelease_not_match_later"),
         pytest.param(VersionInfo(3, 15, 0, "final", 0), ">=3.15.0a6", True, id="final_greater_than_prerelease"),
diff --git a/tests/test_specifier.py b/tests/test_specifier.py
index 2c3d218..dca3024 100644
--- a/tests/test_specifier.py
+++ b/tests/test_specifier.py
@@ -139,6 +139,11 @@ def test_specifier_parse_wildcard() -> None:
         pytest.param(">3.12", "3.12.0", False, id="gt-equal"),
         pytest.param("<3.12", "3.11.0", True, id="lt-below"),
         pytest.param("<3.12", "3.12.0", False, id="lt-equal"),
+        pytest.param("<3.12", "3.12.0rc1", False, id="lt-boundary-prerelease-two-part"),
+        pytest.param("<3.12.0", "3.12.0rc1", False, id="lt-boundary-prerelease-three-part"),
+        pytest.param("<3.12.0rc2", "3.12.0rc1", True, id="lt-explicit-prerelease-bound"),
+        pytest.param("<3.12.0", "3.11.9rc1", True, id="lt-lower-release-prerelease"),
+        pytest.param("<=3.12.0", "3.12.0rc1", True, id="lte-boundary-prerelease"),
         pytest.param("==3.12.0", "3.12.0", True, id="eq-match"),
         pytest.param("==3.12.0", "3.12.1", False, id="eq-no-match"),
         pytest.param("!=3.12.0", "3.12.0", False, id="ne-match"),

From 29b20dc5761e33b3547f468b3beb39dd611e36d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bern=C3=A1t=20G=C3=A1bor?= <gaborjbernat@gmail.com>
Date: Mon, 2 Nov 2026 16:55:31 -0800
Subject: [PATCH 2/2] =?UTF-8?q?=F0=9F=93=9D=20docs(news):=20record=20upper?=
 =?UTF-8?q?-bound=20fix?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 docs/changelog/217.bugfix.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 docs/changelog/217.bugfix.rst

diff --git a/docs/changelog/217.bugfix.rst b/docs/changelog/217.bugfix.rst
new file mode 100644
index 0000000..2d8251e
--- /dev/null
+++ b/docs/changelog/217.bugfix.rst
@@ -0,0 +1 @@
+Exclude prereleases of the final version named by an exclusive upper bound, such as ``<3.12.0`` rejecting ``3.12.0rc1``.