diff --git a/adapters/fabric/build.gradle b/adapters/fabric/build.gradle
index f055c2a72..24b6b7a28 100644
--- a/adapters/fabric/build.gradle
+++ b/adapters/fabric/build.gradle
@@ -201,6 +201,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]
diff --git a/adapters/forge/build.gradle b/adapters/forge/build.gradle
index a10f2349f..1dca2a8d7 100644
--- a/adapters/forge/build.gradle
+++ b/adapters/forge/build.gradle
@@ -200,6 +200,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]
diff --git a/adapters/modded-common/src/main/resources/pack.mcmeta b/adapters/modded-common/src/main/resources/pack.mcmeta
new file mode 100644
index 000000000..1189047ea
--- /dev/null
+++ b/adapters/modded-common/src/main/resources/pack.mcmeta
@@ -0,0 +1,7 @@
+{
+  "pack": {
+    "description": "Iris client resources and mod data",
+    "min_format": [88, 0],
+    "max_format": [107, 1]
+  }
+}
diff --git a/adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedPackMetadataTest.java b/adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedPackMetadataTest.java
new file mode 100644
index 000000000..48d82911c
--- /dev/null
+++ b/adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedPackMetadataTest.java
@@ -0,0 +1,45 @@
+package art.arcane.iris.modded;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.mojang.serialization.JsonOps;
+import net.minecraft.SharedConstants;
+import net.minecraft.server.Bootstrap;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.metadata.pack.PackMetadataSection;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class ModdedPackMetadataTest {
+    @BeforeClass
+    public static void bootstrapMinecraftRegistries() {
+        SharedConstants.tryDetectVersion();
+        Bootstrap.bootStrap();
+    }
+
+    @Test
+    public void metadataLoadsClientResourcesAndServerDataForCurrentMinecraft() throws IOException {
+        try (InputStream resource = ModdedPackMetadataTest.class.getResourceAsStream("/pack.mcmeta")) {
+            assertNotNull(resource);
+            try (InputStreamReader reader = new InputStreamReader(resource, StandardCharsets.UTF_8)) {
+                JsonObject metadata = JsonParser.parseReader(reader).getAsJsonObject();
+                for (PackType type : PackType.values()) {
+                    PackMetadataSection section = PackMetadataSection.forPackType(type).codec()
+                            .parse(JsonOps.INSTANCE, metadata.get("pack")).getOrThrow();
+                    assertEquals("Iris client resources and mod data", section.description().getString());
+                    assertTrue(type.toString(), section.supportedFormats().isValueInRange(
+                            SharedConstants.getCurrentVersion().packVersion(type)));
+                }
+            }
+        }
+    }
+}
diff --git a/adapters/neoforge/build.gradle b/adapters/neoforge/build.gradle
index b995a63d0..fe8632d69 100644
--- a/adapters/neoforge/build.gradle
+++ b/adapters/neoforge/build.gradle
@@ -173,6 +173,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]
diff --git a/build.gradle b/build.gradle
index 345871505..ccd014dad 100644
--- a/build.gradle
+++ b/build.gradle
@@ -576,6 +576,14 @@ tasks.named('check').configure {
 }
 
 List<String> commonModdedArtifactEntries = [
+    'pack.mcmeta',
+    'com/fulcrumgenomics/jlibdeflate/LibdeflateDecompressor.class',
+    'com/fulcrumgenomics/jlibdeflate/LibdeflateException.class',
+    'native/linux-aarch64/libjlibdeflate.so',
+    'native/linux-x86_64/libjlibdeflate.so',
+    'native/osx-aarch64/libjlibdeflate.dylib',
+    'native/osx-x86_64/libjlibdeflate.dylib',
+    'native/windows-x86_64/jlibdeflate.dll',
     'META-INF/iris/generation-kernels/catalog.tsv',
     'META-INF/iris/generation-kernels/abi-1.revision',
     'META-INF/services/art.arcane.iris.localization.IrisMessageContributor',
diff --git a/buildSrc/src/main/java/ModdedArtifactVerifier.java b/buildSrc/src/main/java/ModdedArtifactVerifier.java
index a77cd67fd..f2a10102b 100644
--- a/buildSrc/src/main/java/ModdedArtifactVerifier.java
+++ b/buildSrc/src/main/java/ModdedArtifactVerifier.java
@@ -85,6 +85,11 @@ public final class ModdedArtifactVerifier {
                     throw new GradleException(artifact.getName() + " is missing " + requiredEntry);
                 }
             }
+            if (jar.getJarEntry("assets/irisworldgen/lang/en_us.json") != null
+                    && jar.getJarEntry("pack.mcmeta") == null) {
+                throw new GradleException(artifact.getName()
+                        + " ships Iris client language resources without pack.mcmeta");
+            }
 
             Set<String> bundledRuntimeEntries = new LinkedHashSet<>();
             Set<String> privateReferenceClasses = new LinkedHashSet<>();
diff --git a/buildSrc/src/test/java/ModdedArtifactVerifierTest.java b/buildSrc/src/test/java/ModdedArtifactVerifierTest.java
index 3517999ee..efb9303d2 100644
--- a/buildSrc/src/test/java/ModdedArtifactVerifierTest.java
+++ b/buildSrc/src/test/java/ModdedArtifactVerifierTest.java
@@ -44,6 +44,28 @@ public class ModdedArtifactVerifierTest {
         ModdedArtifactVerifier.verify(artifact, REQUIRED_ENTRIES);
     }
 
+    @Test
+    public void rejectsClientLanguagesWithoutPackMetadata() throws Exception {
+        Map<String, byte[]> entries = validEntries();
+        entries.put("assets/irisworldgen/lang/en_us.json", "{}".getBytes(StandardCharsets.UTF_8));
+        File artifact = createArtifact(entries);
+
+        GradleException failure = assertThrows(GradleException.class,
+                () -> ModdedArtifactVerifier.verify(artifact, REQUIRED_ENTRIES));
+        assertTrue(failure.getMessage().contains("client language resources without pack.mcmeta"));
+    }
+
+    @Test
+    public void acceptsClientLanguagesWithPackMetadata() throws Exception {
+        Map<String, byte[]> entries = validEntries();
+        entries.put("assets/irisworldgen/lang/en_us.json", "{}".getBytes(StandardCharsets.UTF_8));
+        entries.put("pack.mcmeta", ("{\"pack\":{\"description\":\"Iris\","
+                + "\"min_format\":[88,0],\"max_format\":[107,1]}}")
+                .getBytes(StandardCharsets.UTF_8));
+
+        ModdedArtifactVerifier.verify(createArtifact(entries), REQUIRED_ENTRIES);
+    }
+
     @Test
     public void rejectsRelocatedRuntimeReference() throws Exception {
         Map<String, byte[]> entries = validEntries();