feat(release): start from the highest version across all sources

The release base used to be the latest v* tag only. It is now the highest version found in that tag and in every file the release writes: pyproject.toml, CHANGELOG.md, flake.nix, PKGBUILD, the RPM spec, debian/changelog and Cargo.toml. A lagging file can no longer lower the base and a file ahead of the tag raises it; when the sources disagree the release says so and names the version it starts from. Repos whose sources agree release exactly as before.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/unit/pkgmgr/actions/release/test_versioning.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import os
+import tempfile
 import unittest
 from unittest.mock import patch
 
@@ -11,12 +13,23 @@ from pkgmgr.core.version.semver import SemVer
 
 
 class TestDetermineCurrentVersion(unittest.TestCase):
+    def setUp(self) -> None:
+        self._tmp = tempfile.TemporaryDirectory()
+        self.repo = self._tmp.name
+
+    def tearDown(self) -> None:
+        self._tmp.cleanup()
+
+    def _write(self, name: str, content: str) -> None:
+        with open(os.path.join(self.repo, name), "w", encoding="utf-8") as f:
+            f.write(content)
+
     @patch("pkgmgr.actions.release.versioning.get_tags", return_value=[])
     def test_determine_current_version_no_tags_returns_zero(
         self,
         mock_get_tags,
     ) -> None:
-        ver = determine_current_version()
+        ver = determine_current_version(self.repo)
         self.assertIsInstance(ver, SemVer)
         self.assertEqual((ver.major, ver.minor, ver.patch), (0, 0, 0))
         mock_get_tags.assert_called_once()
@@ -31,12 +44,29 @@ class TestDetermineCurrentVersion(unittest.TestCase):
         mock_get_tags.return_value = ["v0.1.0", "v1.2.3"]
         mock_find_latest_version.return_value = ("v1.2.3", SemVer(1, 2, 3))
 
-        ver = determine_current_version()
+        ver = determine_current_version(self.repo)
 
         self.assertEqual((ver.major, ver.minor, ver.patch), (1, 2, 3))
         mock_get_tags.assert_called_once()
         mock_find_latest_version.assert_called_once_with(["v0.1.0", "v1.2.3"])
 
+    @patch("pkgmgr.actions.release.versioning.get_tags", return_value=["v0.3.0"])
+    def test_lagging_cargo_version_does_not_lower_the_base(self, _tags) -> None:
+        self._write("Cargo.toml", '[package]\nname = "x"\nversion = "0.1.0"\n')
+        self._write("CHANGELOG.md", "# Changelog\n\n## [0.3.0] - 2026-10-30\n")
+
+        self.assertEqual(determine_current_version(self.repo), SemVer(0, 3, 0))
+
+    @patch("pkgmgr.actions.release.versioning.get_tags", return_value=["v1.0.0"])
+    def test_file_ahead_of_the_tag_raises_the_base(self, _tags) -> None:
+        self._write("pyproject.toml", '[project]\nname = "x"\nversion = "1.4.0"\n')
+        self._write(
+            "CHANGELOG.md",
+            "# Changelog\n\n## [Unreleased]\n\n## [1.0.0] - 2026-10-01\n",
+        )
+
+        self.assertEqual(determine_current_version(self.repo), SemVer(1, 4, 0))
+
 
 class TestBumpSemVer(unittest.TestCase):
     def test_bump_semver_major(self) -> None: