fix(pathFilter): don't let a release tag on a descendant commit hide pending changes

src/main/kotlin/git/semver/plugin/scm/GitProvider.kt

@@ -161,19 +161,35 @@ internal class GitProvider(internal val settings: SemverSettings) {
     private fun computeRelevantShas(repo: Repository, head: ObjectId, tags: Map<String, List<Tag>>): Set<String>? {
         if (settings.pathFilter.isEmpty()) return null
 
-        val versionTagIds = getVersionTagObjectIds(tags)
+        val versionTagIds = getVersionTagObjectIds(repo, head, tags)
         val releaseMsgIds = findReleaseMessageCommits(repo, head, versionTagIds)
         val boundaryIds = versionTagIds + releaseMsgIds
 
         return filterCommitsByPath(repo, head, boundaryIds)
     }
 
-    private fun getVersionTagObjectIds(tags: Map<String, List<Tag>>): List<ObjectId> {
-        return tags.entries
+    private fun getVersionTagObjectIds(repo: Repository, head: ObjectId, tags: Map<String, List<Tag>>): List<ObjectId> {
+        val candidateIds = tags.entries
             .filter { (_, tagList) -> tagList.any { MutableSemVersion.tryParse(it) != null } }
             .mapNotNull { (sha, _) ->
                 try { ObjectId.fromString(sha) } catch (_: Exception) { null }
             }
+        // Only tags reachable from `head` may bound the walk below.
+        return filterAncestorsOf(repo, head, candidateIds)
+    }
+
+    private fun filterAncestorsOf(repo: Repository, head: ObjectId, candidateIds: List<ObjectId>): List<ObjectId> {
+        if (candidateIds.isEmpty()) return candidateIds
+        return RevWalk(repo).use { walk ->
+            val headCommit = walk.parseCommit(head)
+            candidateIds.filter { oid ->
+                try {
+                    walk.isMergedInto(walk.parseCommit(oid), headCommit)
+                } catch (_: Exception) {
+                    false
+                }
+            }
+        }
     }
 
     private fun findReleaseMessageCommits(repo: Repository, head: ObjectId, boundaryIds: List<ObjectId>): List<ObjectId> {

src/test/kotlin/git/semver/plugin/scm/GitProviderPathFilterTest.kt

@@ -3,6 +3,7 @@ package git.semver.plugin.scm
 import git.semver.plugin.semver.SemverSettings
 import org.assertj.core.api.Assertions.assertThat
 import org.eclipse.jgit.api.Git
+import org.eclipse.jgit.revwalk.RevCommit
 import org.junit.jupiter.api.io.TempDir
 import java.io.File
 import java.nio.file.Files
@@ -21,12 +22,12 @@ class GitProviderPathFilterTest {
         return path.toFile()
     }
 
-    private fun commitFile(git: Git, relPath: String, message: String) {
+    private fun commitFile(git: Git, relPath: String, message: String): RevCommit {
         val file = File(git.repository.workTree, relPath)
         file.parentFile?.mkdirs()
         file.writeText(message)
         git.add().addFilepattern(relPath).call()
-        git.commit().setMessage(message).call()
+        return git.commit().setMessage(message).call()
     }
 
     @Test
@@ -168,4 +169,56 @@ class GitProviderPathFilterTest {
             assertThat(messages).doesNotContain("feat: add service outside lib")
         }
     }
+
+    @Test
+    fun `a release tag on a descendant commit does not hide pending changes on an earlier commit`() {
+        val gitDir = getGitDir("pathFilterDescendantTag")
+        val provider = GitProvider(SemverSettings().apply {
+            pathFilter = "lib"
+            releaseTagNameFormat = "v%s"
+        })
+
+        Git.init().setDirectory(gitDir).call().use { git ->
+            commitFile(git, "README.md", "Initial commit")
+            commitFile(git, "lib/A.kt", "release: 1.0.0")
+            git.tag().setName("v1.0.0").call()
+
+            // Pending change, not yet released.
+            val pendingCommit = commitFile(git, "lib/B.kt", "fix: patch pending in lib")
+
+            // A later commit lands and gets released first (descendant of pendingCommit).
+            commitFile(git, "lib/C.kt", "feat: a later feature also in lib")
+            git.tag().setName("v1.1.0").call()
+
+            // Compute version as of the earlier, still-pending commit.
+            git.checkout().setName(pendingCommit.name).call()
+
+            assertThat(provider.semVersion(git).toVersionString()).isEqualTo("1.0.1-SNAPSHOT")
+        }
+    }
+
+    @Test
+    fun `changelog for an earlier commit is not hidden by a later release tag`() {
+        val gitDir = getGitDir("pathFilterDescendantTagChangelog")
+        val provider = GitProvider(SemverSettings().apply {
+            pathFilter = "lib"
+            releaseTagNameFormat = "v%s"
+        })
+
+        Git.init().setDirectory(gitDir).call().use { git ->
+            commitFile(git, "README.md", "Initial commit")
+            commitFile(git, "lib/A.kt", "release: 1.0.0")
+            git.tag().setName("v1.0.0").call()
+
+            val pendingCommit = commitFile(git, "lib/B.kt", "fix: patch pending in lib")
+
+            commitFile(git, "lib/C.kt", "feat: a later feature also in lib")
+            git.tag().setName("v1.1.0").call()
+
+            git.checkout().setName(pendingCommit.name).call()
+
+            val messages = provider.changeLog(git).map { it.text }
+            assertThat(messages).contains("fix: patch pending in lib")
+        }
+    }
 }