fix(test): JUnit tagging and coverage

src/test/java/org/egothor/stemmer/CompileIntegrationTest.java

@@ -96,6 +96,7 @@ import org.junit.jupiter.params.provider.MethodSource;
 @Tag("cli")
 @Tag("stemmer")
 @Tag("compile")
+@Tag("construction")
 @Tag("slow")
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 @DisplayName("Compile integration")
@@ -184,6 +185,11 @@ final class CompileIntegrationTest {
 
     @Nested
     @DisplayName("Remark-aware fixture workflow")
+    @Tag("integration")
+    @Tag("cli")
+    @Tag("stemmer")
+    @Tag("compile")
+    @Tag("construction")
     final class RemarkAwareFixtureWorkflow {
 
         /**
@@ -306,6 +312,11 @@ final class CompileIntegrationTest {
     @Nested
     @DisplayName("Bundled project dictionary workflows")
     @Tag("slow")
+    @Tag("integration")
+    @Tag("cli")
+    @Tag("stemmer")
+    @Tag("compile")
+    @Tag("construction")
     final class BundledProjectDictionaryWorkflows {
 
         /**

src/test/java/org/egothor/stemmer/CompileTest.java

@@ -70,6 +70,7 @@ import org.junit.jupiter.api.io.TempDir;
 @Tag("cli")
 @Tag("compile")
 @Tag("stemmer")
+@Tag("construction")
 @DisplayName("Compile")
 class CompileTest {
 
@@ -178,6 +179,11 @@ class CompileTest {
 
     @Nested
     @DisplayName("argument validation")
+    @Tag("integration")
+    @Tag("cli")
+    @Tag("compile")
+    @Tag("stemmer")
+    @Tag("validation")
     class ArgumentValidationTest {
 
         @Test

src/test/java/org/egothor/stemmer/DiacriticStripperTest.java

@@ -43,6 +43,7 @@ import org.junit.jupiter.api.Test;
 @Tag("unit")
 @Tag("diacritic")
 @Tag("stemmer")
+@Tag("normalization")
 @DisplayName("DiacriticStripper")
 class DiacriticStripperTest {
 

src/test/java/org/egothor/stemmer/FuzzStemmerAndTrieCompilationTest.java

@@ -68,6 +68,7 @@ import org.junit.jupiter.api.io.TempDir;
 @Tag("fuzz")
 @Tag("trie")
 @Tag("stemmer")
+@Tag("determinism")
 class FuzzStemmerAndTrieCompilationTest {
 
     /**

src/test/java/org/egothor/stemmer/StemmerDictionaryParserTest.java

@@ -76,6 +76,7 @@ import org.junit.jupiter.api.io.TempDir;
 @Tag("unit")
 @Tag("parser")
 @Tag("stemmer")
+@Tag("validation")
 class StemmerDictionaryParserTest {
 
     /**
@@ -98,6 +99,10 @@ class StemmerDictionaryParserTest {
     /**
      * Log handler capturing parser diagnostics for assertions.
      */
+    @Tag("unit")
+    @Tag("parser")
+    @Tag("stemmer")
+    @Tag("validation")
     private static final class CapturedLogHandler extends Handler {
 
         /**
@@ -158,6 +163,10 @@ class StemmerDictionaryParserTest {
 
     @Nested
     @DisplayName("parse(Reader, String, EntryHandler)")
+    @Tag("unit")
+    @Tag("parser")
+    @Tag("stemmer")
+    @Tag("validation")
     class ReaderParsingTests {
 
         @Test
@@ -334,6 +343,10 @@ class StemmerDictionaryParserTest {
 
     @Nested
     @DisplayName("parse(Path, EntryHandler) and parse(String, EntryHandler)")
+    @Tag("unit")
+    @Tag("parser")
+    @Tag("stemmer")
+    @Tag("validation")
     class FileParsingTests {
 
         @Test
@@ -424,6 +437,10 @@ class StemmerDictionaryParserTest {
 
     @Nested
     @DisplayName("ParseStatistics")
+    @Tag("unit")
+    @Tag("parser")
+    @Tag("stemmer")
+    @Tag("validation")
     class ParseStatisticsTests {
 
         @Test

src/test/java/org/egothor/stemmer/StemmerKnowledgeExperimentTest.java

@@ -57,6 +57,7 @@ import org.junit.jupiter.api.io.TempDir;
 @Tag("integration")
 @Tag("stemmer")
 @Tag("trie")
+@Tag("reduction")
 final class StemmerKnowledgeExperimentTest {
 
     /**

src/test/java/org/egothor/stemmer/StemmerPatchTrieBinaryIOTest.java

@@ -134,6 +134,10 @@ class StemmerPatchTrieBinaryIOTest {
      */
     @Nested
     @DisplayName("write(...)")
+    @Tag("unit")
+    @Tag("io")
+    @Tag("trie")
+    @Tag("persistence")
     class WriteTests {
 
         /**
@@ -290,6 +294,10 @@ class StemmerPatchTrieBinaryIOTest {
      */
     @Nested
     @DisplayName("read(...)")
+    @Tag("unit")
+    @Tag("io")
+    @Tag("trie")
+    @Tag("persistence")
     class ReadTests {
 
         /**
@@ -633,6 +641,10 @@ class StemmerPatchTrieBinaryIOTest {
     /**
      * Output stream that records whether it has been closed.
      */
+    @Tag("unit")
+    @Tag("io")
+    @Tag("trie")
+    @Tag("persistence")
     private static final class TrackingOutputStream extends ByteArrayOutputStream {
 
         /**
@@ -659,6 +671,10 @@ class StemmerPatchTrieBinaryIOTest {
     /**
      * Input stream that records whether it has been closed.
      */
+    @Tag("unit")
+    @Tag("io")
+    @Tag("trie")
+    @Tag("persistence")
     private static final class TrackingInputStream extends ByteArrayInputStream {
 
         /**

src/test/java/org/egothor/stemmer/StemmerPatchTrieLoaderTest.java

@@ -89,6 +89,8 @@ import org.junit.jupiter.params.provider.MethodSource;
 @Tag("stemmer")
 @Tag("io")
 @Tag("parser")
+@Tag("trie")
+@Tag("persistence")
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 final class StemmerPatchTrieLoaderTest {
 
@@ -266,6 +268,9 @@ final class StemmerPatchTrieLoaderTest {
      */
     @Nested
     @DisplayName("API contracts")
+    @Tag("validation")
+    @Tag("integration")
+    @Tag("trie")
     final class ApiContractTests {
 
         /**
@@ -314,11 +319,83 @@ final class StemmerPatchTrieLoaderTest {
         }
     }
 
+    /**
+     * Focused internal loader behavior tests.
+     */
+    @Nested
+    @DisplayName("Internal helper behavior")
+    @Tag("construction")
+    @Tag("integration")
+    @Tag("trie")
+    final class InternalLoaderBehaviorTests {
+
+        /**
+         * Verifies that bundled language loading follows explicit
+         * right-to-left metadata mapping.
+         */
+        @Test
+        @DisplayName("bundled language loading must infer traversal direction from language metadata")
+        void shouldLoadBundledLanguagesUsingLanguageRightToLeftMetadata() throws IOException {
+            final ReductionSettings settings = ReductionSettings.withDefaults(DEFAULT_REDUCTION_MODE);
+            final FrequencyTrie<String> leftToRightDictionary = StemmerPatchTrieLoader.load(
+                    StemmerPatchTrieLoader.Language.US_UK, true, settings);
+            final FrequencyTrie<String> rightToLeftDictionary = StemmerPatchTrieLoader.load(
+                    StemmerPatchTrieLoader.Language.FA_IR, true, settings);
+
+            assertEquals(WordTraversalDirection.BACKWARD, leftToRightDictionary.traversalDirection(),
+                    "Left-to-right languages should use backward traversal.");
+            assertEquals(WordTraversalDirection.FORWARD, rightToLeftDictionary.traversalDirection(),
+                    "Right-to-left languages should use forward traversal.");
+        }
+
+        /**
+         * Verifies the mode-based and settings-based bundled load overloads remain
+         * semantically consistent for traversal direction.
+         */
+        @Test
+        @DisplayName("load(Language,.., ReductionMode) and load(Language,.., ReductionSettings) should agree on traversal direction")
+        void shouldKeepBundledTraversalDirectionConsistentAcrossOverloads() throws IOException {
+            final FrequencyTrie<String> byMode = StemmerPatchTrieLoader.load(
+                    StemmerPatchTrieLoader.Language.US_UK, true, DEFAULT_REDUCTION_MODE);
+            final FrequencyTrie<String> bySettings = StemmerPatchTrieLoader.load(
+                    StemmerPatchTrieLoader.Language.US_UK, true,
+                    ReductionSettings.withDefaults(DEFAULT_REDUCTION_MODE));
+
+            assertEquals(byMode.traversalDirection(), bySettings.traversalDirection());
+            assertEquals(byMode.metadata().reductionSettings().reductionMode(),
+                    bySettings.metadata().reductionSettings().reductionMode());
+        }
+
+        /**
+         * Verifies bundled resource access succeeds for known resources and fails
+         * for unknown resources.
+         */
+        @Test
+        @DisplayName("openBundledResource should return readable streams for known resources and fail for unknown ones")
+        void shouldOpenBundledResourcesSuccessfullyAndRejectUnknowns() throws IOException {
+            final String resourcePath = StemmerPatchTrieLoader.Language.US_UK.resourcePath();
+            try (InputStream inputStream = StemmerPatchTrieLoader.openBundledResource(resourcePath);
+                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
+                assertNotNull(reader.readLine(), "Known bundled resource must expose readable content.");
+            }
+
+            final String missingResource = "org/egothor/stemmer/missing-dictionary.dict.gz";
+            final IOException exception = assertThrows(IOException.class,
+                    () -> StemmerPatchTrieLoader.openBundledResource(missingResource));
+
+            assertEquals("Stemmer resource not found: " + missingResource, exception.getMessage());
+        }
+    }
+
     /**
      * Focused filesystem and parser behavior tests.
      */
     @Nested
     @DisplayName("Filesystem and parser behavior")
+    @Tag("io")
+    @Tag("construction")
+    @Tag("integration")
+    @Tag("trie")
     final class FilesystemAndParserTests {
 
         /**
@@ -578,6 +655,9 @@ final class StemmerPatchTrieLoaderTest {
     @Nested
     @Tag("slow")
     @DisplayName("Bundled dictionaries")
+    @Tag("compat")
+    @Tag("trie")
+    @Tag("regression")
     final class BundledDictionaryTests {
 
         /**

src/test/java/org/egothor/stemmer/TrieMetadataTest.java

@@ -42,6 +42,7 @@ import org.junit.jupiter.api.Test;
 @Tag("unit")
 @Tag("metadata")
 @Tag("trie")
+@Tag("validation")
 @DisplayName("TrieMetadata")
 class TrieMetadataTest {
 

src/test/java/org/egothor/stemmer/WordTraversalDirectionTest.java

@@ -42,6 +42,7 @@ import org.junit.jupiter.api.Test;
 @Tag("unit")
 @Tag("core")
 @Tag("stemmer")
+@Tag("validation")
 @DisplayName("WordTraversalDirection")
 class WordTraversalDirectionTest {
 

src/test/java/org/egothor/stemmer/trie/ChildDescriptorTest.java

@@ -46,6 +46,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("ChildDescriptor")
 class ChildDescriptorTest {
 

src/test/java/org/egothor/stemmer/trie/DominantLocalDescriptorTest.java

@@ -42,6 +42,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("DominantLocalDescriptor")
 class DominantLocalDescriptorTest {
 

src/test/java/org/egothor/stemmer/trie/LocalValueSummaryTest.java

@@ -51,6 +51,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("LocalValueSummary")
 class LocalValueSummaryTest {
 
@@ -190,6 +191,9 @@ class LocalValueSummaryTest {
     /**
      * Test helper with identical textual form but distinct identity.
      */
+    @Tag("unit")
+    @Tag("trie")
+    @Tag("reduction")
     private static final class TextTwin {
 
         /**

src/test/java/org/egothor/stemmer/trie/MutableNodeTest.java

@@ -45,6 +45,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("construction")
 @DisplayName("MutableNode")
 class MutableNodeTest {
 

src/test/java/org/egothor/stemmer/trie/RankedLocalDescriptorTest.java

@@ -42,6 +42,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("RankedLocalDescriptor")
 class RankedLocalDescriptorTest {
 

src/test/java/org/egothor/stemmer/trie/ReducedNodeTest.java

@@ -49,6 +49,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("ReducedNode")
 class ReducedNodeTest {
 

src/test/java/org/egothor/stemmer/trie/ReductionContextTest.java

@@ -48,6 +48,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("ReductionContext")
 class ReductionContextTest {
 

src/test/java/org/egothor/stemmer/trie/ReductionSignatureTest.java

@@ -47,6 +47,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("ReductionSignature")
 class ReductionSignatureTest {
 

src/test/java/org/egothor/stemmer/trie/UnorderedLocalDescriptorTest.java

@@ -42,6 +42,7 @@ import org.junit.jupiter.api.Test;
  */
 @Tag("unit")
 @Tag("trie")
+@Tag("reduction")
 @DisplayName("UnorderedLocalDescriptor")
 class UnorderedLocalDescriptorTest {