fix(semver): skip non-semver tags when picking latest existing tag

Rolling tags like 'v1' (and any other tag that doesn't parse as x.y.z
after prefix stripping) used to enter the latest-tag candidate set in
CalculateSemver. When such a tag shared a commit with a real semver tag
(e.g. v1 and v1.16.3 both pointing at the same release commit), go-git's
alphabetical tag iteration made 'v1' win, ParseExistingSemver bailed out
because '1' has only one component, and the calculator silently reset
the baseline to 0.0.0 — producing nonsense like 0.0.5 on this branch.

ListExistingTags now filters tags through a new IsParseableSemverTag
helper before recording them, so non-semver tags never participate in
latest-tag selection. The behavior change is invisible for repos that
only use proper vX.Y.Z tags, and it's covered by a new test table.

cmd/main.go

@@ -129,7 +129,7 @@ func main() {
 
 		// List existing tags if needed
 		if params.varExisting || repo.Config.Force.Existing {
-			utils.ListExistingTags(&repo.GitRepo)
+			utils.ListExistingTags(&repo.GitRepo, repo.Config.TagPrefixes)
 		}
 
 		// Apply forced versioning

cmd/utils/git.go

@@ -163,10 +163,13 @@ func ListCommits(repo *GitRepository) ([]CommitDetails, error) {
 }
 
 // ListExistingTags lists all tags in the repository
-func ListExistingTags(repo *GitRepository) {
+// ListExistingTags lists all tags in the repository.
+// Tags that don't parse as proper semver (rolling tags like "v1" or "latest")
+// are skipped so they can't out-rank real semver tags pointing to the same
+// commit during latest-tag selection.
+func ListExistingTags(repo *GitRepository, tagPrefixes []string) {
 	Debug("Listing existing tags", nil)
 
-	// Check if Handler is nil to avoid panic
 	if repo.Handler == nil {
 		Debug("Repository handler is nil, skipping tag listing", nil)
 		return
@@ -180,15 +183,17 @@ func ListExistingTags(repo *GitRepository) {
 
 	if err := refs.ForEach(func(ref *plumbing.Reference) error {
 		tagName := ref.Name().Short()
-		commitHash := ref.Hash().String()
 
-		// For annotated tags, dereference to get the actual commit hash
+		if !IsParseableSemverTag(tagName, tagPrefixes) {
+			Debug("Skipping non-semver tag", map[string]interface{}{"tag": tagName})
+			return nil
+		}
+
+		commitHash := ref.Hash().String()
 		tagObj, err := repo.Handler.TagObject(ref.Hash())
 		if err == nil {
-			// This is an annotated tag - get the commit it points to
 			commitHash = tagObj.Target.String()
 		}
-		// If err != nil, it's a lightweight tag - ref.Hash() is already the commit hash
 
 		repo.Tags = append(repo.Tags, TagDetails{
 			Name: tagName,

cmd/utils/git_test.go

@@ -142,7 +142,7 @@ func TestListExistingTags(t *testing.T) {
 		repo := &GitRepository{}
 
 		// Now we can safely call ListExistingTags since we've added a nil check
-		ListExistingTags(repo)
+		ListExistingTags(repo, nil)
 
 		// Verify no tags were added
 		assert.Empty(t, repo.Tags, "Should have no tags after calling with nil Handler")

cmd/utils/version.go

@@ -83,6 +83,29 @@ func StripTagPrefix(tagName string, prefixes []string) string {
 	return result
 }
 
+// IsParseableSemverTag reports whether tagName looks like a proper semver tag
+// (X.Y.Z, optionally vX.Y.Z, optionally with -rc.N suffix) after configured
+// prefixes are stripped. Rolling tags like "v1" or "latest" return false so the
+// calculator can skip them when picking the latest existing tag — preventing a
+// rolling tag tied to the same commit as a real semver tag from "winning" the
+// alphabetical iteration in go-git and resetting the baseline to 0.0.0.
+func IsParseableSemverTag(tagName string, prefixes []string) bool {
+	clean := StripTagPrefix(tagName, prefixes)
+	if idx := strings.Index(clean, "-rc."); idx != -1 {
+		clean = clean[:idx]
+	}
+	parts := strings.Split(clean, ".")
+	if len(parts) < 3 {
+		return false
+	}
+	for _, p := range parts[:3] {
+		if len(extractNumber.FindAllString(p, -1)) == 0 {
+			return false
+		}
+	}
+	return true
+}
+
 // ParseExistingSemver parses a semantic version from a tag name
 func ParseExistingSemver(tagName string, currentSemver SemVer, prefixes []string) SemVer {
 	Debug("Parsing existing semver", map[string]interface{}{"tag": tagName})

cmd/utils/version_test.go

@@ -189,6 +189,34 @@ func TestParseExistingSemver(t *testing.T) {
 		})
 	}
 }
+func TestIsParseableSemverTag(t *testing.T) {
+	InitLogger(false)
+
+	tests := []struct {
+		name     string
+		tag      string
+		prefixes []string
+		want     bool
+	}{
+		{name: "plain x.y.z", tag: "1.2.3", want: true},
+		{name: "v prefix", tag: "v1.16.5", want: true},
+		{name: "v prefix with rc", tag: "v2.0.0-rc.3", want: true},
+		{name: "configured app- prefix", tag: "app-1.2.3", prefixes: []string{"app-"}, want: true},
+
+		{name: "rolling v1 tag", tag: "v1", want: false},
+		{name: "rolling latest tag", tag: "latest", want: false},
+		{name: "two-component", tag: "1.2", want: false},
+		{name: "empty", tag: "", want: false},
+		{name: "non-numeric major", tag: "vX.Y.Z", want: false},
+		{name: "just text", tag: "release-day", want: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, IsParseableSemverTag(tt.tag, tt.prefixes))
+		})
+	}
+}
 
 func TestCheckMatches(t *testing.T) {
 	// Initialize logger for tests