diff --git a/.github/workflows/main-ci.yml b/.github/workflows/main-ci.yml
index fab37f4a7..678db0fb6 100644
--- a/.github/workflows/main-ci.yml
+++ b/.github/workflows/main-ci.yml
@@ -59,6 +59,16 @@ jobs:
       run: ./tools/parse-reports.py
       if: ${{ failure() }}
 
+    - name: 📤 Upload Test Reports
+      uses: actions/upload-artifact@v7
+      if: ${{ !cancelled() }}
+      with:
+        name: Tests
+        path: |
+          projects/*/build/test-results/test/open-test-report.xml
+          projects/*/build/test-results/runGametest.xml
+        retention-days: 1
+
   build-core:
     strategy:
       fail-fast: false
diff --git a/.github/workflows/make-doc.yml b/.github/workflows/make-doc.yml
index 29632d43f..4b66261ae 100644
--- a/.github/workflows/make-doc.yml
+++ b/.github/workflows/make-doc.yml
@@ -33,3 +33,4 @@ jobs:
       with:
         name: Documentation
         path: ./projects/web/build/site/
+        retention-days: 1
diff --git a/build-logic/base/src/main/kotlin/cc-tweaked.java-convention.gradle.kts b/build-logic/base/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
index f61fd99a1..e7063b12c 100644
--- a/build-logic/base/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
+++ b/build-logic/base/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
@@ -172,6 +172,14 @@ tasks.test {
     testLogging {
         events("skipped", "failed")
     }
+
+    // Enable open test reporting
+    jvmArgumentProviders.add {
+        listOf(
+            "-Djunit.platform.reporting.open.xml.enabled=true",
+            "-Djunit.platform.reporting.output.dir=${reports.junitXml.outputLocation.getAbsolutePath()}",
+        )
+    }
 }
 
 tasks.withType(JacocoReport::class.java).configureEach {
diff --git a/build-logic/base/src/main/kotlin/cc-tweaked.published-mod.gradle.kts b/build-logic/base/src/main/kotlin/cc-tweaked.published-mod.gradle.kts
index 0faf2d9ee..a11c391e3 100644
--- a/build-logic/base/src/main/kotlin/cc-tweaked.published-mod.gradle.kts
+++ b/build-logic/base/src/main/kotlin/cc-tweaked.published-mod.gradle.kts
@@ -54,13 +54,6 @@ val verifyClassesMatch = tasks.register<VerifyJavaCompile>("verifyClassesMatch")
         check("MissingOverride", CheckSeverity.OFF)
         check("LoaderOverride", CheckSeverity.DEFAULT)
         check("MissingLoaderOverride", CheckSeverity.DEFAULT)
-
-        // FIXME: We disable JSpecify in the common classes due to some NullAway bugs. As the two
-        //  modes are not compatible, we have to disable NullAway entirely here. This can be removed
-        //  when we bump to 0.14.3.
-        check("NullAway", CheckSeverity.WARN)
-        option("NullAway:JSpecifyMode", false)
-        option("NullAway:JSpecifyExperimental", false)
     }
 
     source = minecraftEmbeddedProjectResolved.map {
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 5b2a996fc..8c6170684 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -53,10 +53,11 @@ create-fabric = "6.0.7.0+mc1.20.1-build.1716"
 
 # Testing
 hamcrest = "3.0"
+jmh = "1.37"
 jqwik = "1.10.1"
 junit = "6.1.3"
 junitPlatform = "6.1.3"
-jmh = "1.37"
+openTestReporting = "0.3.0"
 
 # Build tools
 cctJavadoc = "1.9.0"
@@ -71,7 +72,7 @@ illuaminate = "0.1.0-83-g1131f68"
 lwjgl = "3.4.3"
 minotaur = "2.9.0"
 modDevGradle = "2.0.147"
-nullAway = "0.14.2"
+nullAway = "0.14.3"
 shadow = "9.6.1"
 spotless = "8.10.4"
 teavm = "0.16.0"
@@ -129,15 +130,17 @@ sodium-forge = { module = "maven.modrinth:sodium", version.ref = "sodium.forge"
 
 # Testing
 hamcrest = { module = "org.hamcrest:hamcrest", version.ref = "hamcrest" }
+jmh = { module = "org.openjdk.jmh:jmh-core", version.ref = "jmh" }
+jmh-processor = { module = "org.openjdk.jmh:jmh-generator-annprocess", version.ref = "jmh" }
 jqwik-api = { module = "net.jqwik:jqwik-api", version.ref = "jqwik" }
 jqwik-engine = { module = "net.jqwik:jqwik-engine", version.ref = "jqwik" }
 junit-jupiter-api = { module = "org.junit.jupiter:junit-jupiter-api", version.ref = "junit" }
 junit-jupiter-engine = { module = "org.junit.jupiter:junit-jupiter-engine", version.ref = "junit" }
 junit-jupiter-params = { module = "org.junit.jupiter:junit-jupiter-params", version.ref = "junit" }
 junit-platform-launcher = { module = "org.junit.platform:junit-platform-launcher", version.ref = "junitPlatform" }
+junit-platform-reporting = { module = "org.junit.platform:junit-platform-reporting", version.ref = "junitPlatform" }
+openTestReporting = { module = "org.opentest4j.reporting:open-test-reporting-events", version.ref = "openTestReporting" }
 slf4j-simple = { module = "org.slf4j:slf4j-simple", version.ref = "slf4j" }
-jmh = { module = "org.openjdk.jmh:jmh-core", version.ref = "jmh" }
-jmh-processor = { module = "org.openjdk.jmh:jmh-generator-annprocess", version.ref = "jmh" }
 
 # LWJGL
 lwjgl-bom = { module = "org.lwjgl:lwjgl-bom", version.ref = "lwjgl" }
@@ -192,7 +195,7 @@ externalMods-fabric-runtime = ["jei-fabric", "modmenu"]
 
 # Testing
 test = ["junit-jupiter-api", "junit-jupiter-params", "hamcrest", "jqwik-api"]
-testRuntime = ["junit-jupiter-engine", "junit-platform-launcher", "jqwik-engine"]
+testRuntime = ["junit-jupiter-engine", "junit-platform-launcher", "junit-platform-reporting", "jqwik-engine"]
 
 # Build tools
 teavm-api = ["teavm-jso", "teavm-jso-apis", "teavm-platform", "teavm-classlib", "teavm-extension-apis"]
diff --git a/projects/common-api/src/main/java/dan200/computercraft/impl/package-info.java b/projects/common-api/src/main/java/dan200/computercraft/impl/package-info.java
index 0dfb78140..d7dea23f9 100644
--- a/projects/common-api/src/main/java/dan200/computercraft/impl/package-info.java
+++ b/projects/common-api/src/main/java/dan200/computercraft/impl/package-info.java
@@ -2,8 +2,8 @@
 //
 // SPDX-License-Identifier: MPL-2.0
 
-@ApiStatus.Internal
 @NullMarked
+@ApiStatus.Internal
 package dan200.computercraft.impl;
 
 import org.jetbrains.annotations.ApiStatus;
diff --git a/projects/common/build.gradle.kts b/projects/common/build.gradle.kts
index fcad56b21..e05086744 100644
--- a/projects/common/build.gradle.kts
+++ b/projects/common/build.gradle.kts
@@ -8,7 +8,6 @@ import cc.tweaked.gradle.MergeTrees
 import cc.tweaked.gradle.annotationProcessorEverywhere
 import cc.tweaked.vanillaextract.configurations.Capabilities.clientClasses
 import cc.tweaked.vanillaextract.configurations.Capabilities.commonClasses
-import net.ltgt.gradle.errorprone.errorprone
 
 plugins {
     `java-test-fixtures`
@@ -69,19 +68,12 @@ dependencies {
     testModCompileOnly(libs.mixin)
     testModImplementation(testFixtures(project(":core")))
     testModImplementation(testFixtures(project(":common")))
+    testModImplementation(libs.openTestReporting)
     testModImplementation(libs.bundles.kotlin)
 
     "cctJavadoc"(libs.cctJavadoc)
 }
 
-// TODO: Enable JSpecify in the common classes. Unfortunately there's several bugs blocking us right now.
-tasks.compileJava {
-    options.errorprone {
-        option("NullAway:JSpecifyMode", false)
-        option("NullAway:JSpecifyExperimental", false)
-    }
-}
-
 illuaminate {
     version = libs.versions.illuaminate
 }
diff --git a/projects/common/src/client/java/dan200/computercraft/client/integration/ShaderMod.java b/projects/common/src/client/java/dan200/computercraft/client/integration/ShaderMod.java
index 6a1d64847..9c6a236ad 100644
--- a/projects/common/src/client/java/dan200/computercraft/client/integration/ShaderMod.java
+++ b/projects/common/src/client/java/dan200/computercraft/client/integration/ShaderMod.java
@@ -7,7 +7,6 @@ package dan200.computercraft.client.integration;
 import dan200.computercraft.client.render.RenderTypes;
 import dan200.computercraft.client.render.text.DirectFixedWidthFontRenderer;
 import dan200.computercraft.client.render.vbo.DirectVertexBuffer;
-import dan200.computercraft.core.util.Nullability;
 
 import java.nio.ByteBuffer;
 import java.util.Optional;
@@ -49,10 +48,10 @@ public class ShaderMod {
     }
 
     private static final class Storage {
-        static final ShaderMod INSTANCE = Nullability.assertNonNull(ServiceLoader.load(Provider.class)
+        static final ShaderMod INSTANCE = ServiceLoader.load(Provider.class)
             .stream()
             .flatMap(x -> x.get().get().stream())
             .findFirst()
-            .orElseGet(ShaderMod::new));
+            .orElseGet(ShaderMod::new);
     }
 }
diff --git a/projects/common/src/main/java/dan200/computercraft/impl/AbstractUpgradeHolder.java b/projects/common/src/main/java/dan200/computercraft/impl/AbstractUpgradeHolder.java
index cb757e7b5..36eb2c9f2 100644
--- a/projects/common/src/main/java/dan200/computercraft/impl/AbstractUpgradeHolder.java
+++ b/projects/common/src/main/java/dan200/computercraft/impl/AbstractUpgradeHolder.java
@@ -79,7 +79,7 @@ public abstract class AbstractUpgradeHolder<U extends UpgradeBase> {
         this.data = data;
     }
 
-    public final ItemStack getItem() {
+    public final @Unmodifiable ItemStack getItem() {
         return item;
     }
 
diff --git a/projects/common/src/main/java/dan200/computercraft/impl/UpgradeHandleImpl.java b/projects/common/src/main/java/dan200/computercraft/impl/UpgradeHandleImpl.java
index ec53af0af..b528444f9 100644
--- a/projects/common/src/main/java/dan200/computercraft/impl/UpgradeHandleImpl.java
+++ b/projects/common/src/main/java/dan200/computercraft/impl/UpgradeHandleImpl.java
@@ -45,7 +45,7 @@ final class UpgradeHandleImpl<U extends UpgradeBase> implements UpgradeHandle<U>
             );
         }
 
-        if (ItemStack.isSameItemSameComponents(holder.getItem(), newItem)) return;
+        if (ItemStack.matches(holder.getItem(), newItem)) return;
 
         if (!upgrade.value().getCraftingIngredient().test(newItem) || !upgrade.value().isItemSuitable(newItem)) {
             throw new IllegalArgumentException(
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/ModRegistry.java b/projects/common/src/main/java/dan200/computercraft/shared/ModRegistry.java
index 0dd521f5f..7551488cd 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/ModRegistry.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/ModRegistry.java
@@ -483,7 +483,7 @@ public final class ModRegistry {
         static {
             register("tracking_field", TrackingFieldArgumentType.class, TrackingFieldArgumentType.metric());
             register("computer", ComputerArgumentType.class, ComputerArgumentType.get());
-            registerUnsafe("repeat", RepeatArgumentType.class, new RepeatArgumentType.TypeInfo());
+            registerUnsafe("repeat", RepeatArgumentType.class, RepeatArgumentType.type());
         }
     }
 
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ArgumentUtils.java b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ArgumentUtils.java
index e834f4890..84dfee607 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ArgumentUtils.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ArgumentUtils.java
@@ -13,13 +13,14 @@ import net.minecraft.commands.synchronization.ArgumentTypeInfo;
 import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.network.chat.Component;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Utilities for working with arguments.
  *
  * @see net.minecraft.commands.synchronization.ArgumentUtils
  */
-public class ArgumentUtils {
+class ArgumentUtils {
     public static <A extends ArgumentType<?>> JsonObject serializeToJson(ArgumentTypeInfo.Template<A> template) {
         var object = new JsonObject();
         object.addProperty("type", "argument");
@@ -33,7 +34,9 @@ public class ArgumentUtils {
     }
 
     @SuppressWarnings("unchecked")
-    private static <A extends ArgumentType<?>, T extends ArgumentTypeInfo.Template<A>> void serializeToJson(JsonObject jsonObject, ArgumentTypeInfo<A, T> argumentTypeInfo, ArgumentTypeInfo.Template<A> template) {
+    private static <A extends ArgumentType<?>, T extends ArgumentTypeInfo.@Nullable Template<A>> void serializeToJson(
+        JsonObject jsonObject, ArgumentTypeInfo<A, T> argumentTypeInfo, ArgumentTypeInfo.Template<A> template
+    ) {
         argumentTypeInfo.serializeToJson((T) template, jsonObject);
     }
 
@@ -42,7 +45,9 @@ public class ArgumentUtils {
     }
 
     @SuppressWarnings("unchecked")
-    private static <A extends ArgumentType<?>, T extends ArgumentTypeInfo.Template<A>> void serializeToNetwork(FriendlyByteBuf buffer, ArgumentTypeInfo<A, T> type, ArgumentTypeInfo.Template<A> template) {
+    private static <A extends ArgumentType<?>, T extends ArgumentTypeInfo.@Nullable Template<A>> void serializeToNetwork(
+        FriendlyByteBuf buffer, ArgumentTypeInfo<A, T> type, ArgumentTypeInfo.Template<A> template
+    ) {
         buffer.writeVarInt(BuiltInRegistries.COMMAND_ARGUMENT_TYPE.getIdOrThrow(type));
         type.serializeToNetwork((T) template, buffer);
     }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ComputerSelector.java b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ComputerSelector.java
index de74a6bba..7abfeb8eb 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ComputerSelector.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ComputerSelector.java
@@ -353,7 +353,7 @@ public record ComputerSelector(
         CompletableFuture<Suggestions> suggest(CommandContext<?> source, SuggestionsBuilder builder);
     }
 
-    private static SuggestionProvider suggestComputers(Function<ServerComputer, String> renderer) {
+    private static SuggestionProvider suggestComputers(Function<ServerComputer, @Nullable String> renderer) {
         return (anyContext, builder) -> suggestOnServer(anyContext, context -> {
             var remaining = builder.getRemaining();
             for (var computer : ServerContext.get(context.getSource().getServer()).registry().getComputers()) {
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/RepeatArgumentType.java b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/RepeatArgumentType.java
index f1cb8e620..cfe02caea 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/RepeatArgumentType.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/command/arguments/RepeatArgumentType.java
@@ -25,38 +25,26 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
-import java.util.function.BiConsumer;
 
 /**
  * Reads one argument multiple times.
  * <p>
  * Note that this must be the last element in an argument chain: in order to improve the quality of error messages,
  * we will always try to consume another argument while there is input remaining.
- * <p>
- * One problem with how parsers function, is that they must consume some input: and thus we
  *
- * @param <T> The type of each value returned
- * @param <U> The type of the inner parser. This will normally be a {@link List} or {@code T}.
+ * @param <T> The type of each value returned.
  */
-public final class RepeatArgumentType<T, U> implements ArgumentType<List<T>> {
-    private final ArgumentType<U> child;
-    private final BiConsumer<List<T>, U> appender;
-    private final boolean flatten;
+public final class RepeatArgumentType<T> implements ArgumentType<List<T>> {
+    private final ArgumentType<T> child;
     private final SimpleCommandExceptionType some;
 
-    private RepeatArgumentType(ArgumentType<U> child, BiConsumer<List<T>, U> appender, boolean flatten, SimpleCommandExceptionType some) {
+    private RepeatArgumentType(ArgumentType<T> child, SimpleCommandExceptionType some) {
         this.child = child;
-        this.appender = appender;
-        this.flatten = flatten;
         this.some = some;
     }
 
-    public static <T> RepeatArgumentType<T, T> some(ArgumentType<T> appender, SimpleCommandExceptionType missing) {
-        return new RepeatArgumentType<>(appender, List::add, false, missing);
-    }
-
-    public static <T> RepeatArgumentType<T, List<T>> someFlat(ArgumentType<List<T>> appender, SimpleCommandExceptionType missing) {
-        return new RepeatArgumentType<>(appender, List::addAll, true, missing);
+    public static <T> RepeatArgumentType<T> some(ArgumentType<T> appender, SimpleCommandExceptionType missing) {
+        return new RepeatArgumentType<>(appender, missing);
     }
 
     @Override
@@ -68,7 +56,7 @@ public final class RepeatArgumentType<T, U> implements ArgumentType<List<T>> {
             if (!reader.canRead()) break;
 
             var startParse = reader.getCursor();
-            appender.accept(out, child.parse(reader));
+            out.add(child.parse(reader));
             hadSome = true;
 
             if (reader.getCursor() == startParse) {
@@ -111,47 +99,49 @@ public final class RepeatArgumentType<T, U> implements ArgumentType<List<T>> {
         return child.getExamples();
     }
 
-    public static class TypeInfo implements ArgumentTypeInfo<RepeatArgumentType<?, ?>, Template> {
+    public static <T> ArgumentTypeInfo<RepeatArgumentType<T>, ? extends ArgumentTypeInfo.Template<RepeatArgumentType<T>>> type() {
+        return new TypeInfo<>();
+    }
+
+    private static final class TypeInfo<T> implements ArgumentTypeInfo<RepeatArgumentType<T>, Template<T>> {
         @Override
-        public void serializeToNetwork(RepeatArgumentType.Template arg, FriendlyByteBuf buf) {
-            buf.writeBoolean(arg.flatten);
+        public void serializeToNetwork(RepeatArgumentType.Template<T> arg, FriendlyByteBuf buf) {
             ArgumentUtils.serializeToNetwork(buf, arg.child);
             ComponentSerialization.TRUSTED_CONTEXT_FREE_STREAM_CODEC.encode(buf, ArgumentUtils.getMessage(arg.some));
         }
 
         @Override
-        public RepeatArgumentType.Template deserializeFromNetwork(FriendlyByteBuf buf) {
-            var isList = buf.readBoolean();
-            var child = ArgumentUtils.deserialize(buf);
+        public RepeatArgumentType.Template<T> deserializeFromNetwork(FriendlyByteBuf buf) {
+            @SuppressWarnings("unchecked")
+            var child = (ArgumentTypeInfo.Template<ArgumentType<T>>) ArgumentUtils.deserialize(buf);
+
             var message = ComponentSerialization.TRUSTED_CONTEXT_FREE_STREAM_CODEC.decode(buf);
-            return new RepeatArgumentType.Template(this, child, isList, new SimpleCommandExceptionType(message));
+            return new RepeatArgumentType.Template<>(this, child, new SimpleCommandExceptionType(message));
         }
 
         @Override
-        public RepeatArgumentType.Template unpack(RepeatArgumentType<?, ?> argumentType) {
-            return new RepeatArgumentType.Template(this, ArgumentTypeInfos.unpack(argumentType.child), argumentType.flatten, argumentType.some);
+        public RepeatArgumentType.Template<T> unpack(RepeatArgumentType<T> argumentType) {
+            return new RepeatArgumentType.Template<T>(this, ArgumentTypeInfos.unpack(argumentType.child), argumentType.some);
         }
 
         @Override
-        public void serializeToJson(RepeatArgumentType.Template arg, JsonObject json) {
-            json.addProperty("flatten", arg.flatten);
+        public void serializeToJson(RepeatArgumentType.Template<T> arg, JsonObject json) {
             json.add("child", ArgumentUtils.serializeToJson(arg.child));
             json.addProperty("error", Component.Serializer.toJson(ArgumentUtils.getMessage(arg.some), RegistryAccess.EMPTY));
         }
     }
 
-    public record Template(
-        TypeInfo info, ArgumentTypeInfo.Template<?> child, boolean flatten, SimpleCommandExceptionType some
-    ) implements ArgumentTypeInfo.Template<RepeatArgumentType<?, ?>> {
+    private record Template<T>(
+        TypeInfo<T> info, ArgumentTypeInfo.Template<ArgumentType<T>> child, SimpleCommandExceptionType some
+    ) implements ArgumentTypeInfo.Template<RepeatArgumentType<T>> {
         @Override
-        @SuppressWarnings({ "unchecked", "rawtypes" })
-        public RepeatArgumentType<?, ?> instantiate(CommandBuildContext commandBuildContext) {
+        public RepeatArgumentType<T> instantiate(CommandBuildContext commandBuildContext) {
             var child = child().instantiate(commandBuildContext);
-            return flatten ? RepeatArgumentType.someFlat((ArgumentType) child, some()) : RepeatArgumentType.some(child, some());
+            return RepeatArgumentType.some(child, some());
         }
 
         @Override
-        public ArgumentTypeInfo<RepeatArgumentType<?, ?>, ?> type() {
+        public ArgumentTypeInfo<RepeatArgumentType<T>, ?> type() {
             return info;
         }
     }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/command/builder/CommandBuilder.java b/projects/common/src/main/java/dan200/computercraft/shared/command/builder/CommandBuilder.java
index 5f9372b71..99d761090 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/command/builder/CommandBuilder.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/command/builder/CommandBuilder.java
@@ -17,7 +17,6 @@ import org.jspecify.annotations.Nullable;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Predicate;
-import java.util.function.Supplier;
 
 import static dan200.computercraft.shared.command.Exceptions.ARGUMENT_EXPECTED;
 import static dan200.computercraft.shared.command.builder.HelpingArgumentBuilder.literal;
@@ -58,27 +57,19 @@ public class CommandBuilder<S> implements CommandNodeBuilder<S, Command<S>> {
     }
 
     public <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argManyValue(String name, ArgumentType<T> type, List<T> empty) {
-        return argMany(name, type, () -> empty);
+        return argMany(name, RepeatArgumentType.some(type, ARGUMENT_EXPECTED), empty);
     }
 
     public <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argManyValue(String name, ArgumentType<T> type, T defaultValue) {
         return argManyValue(name, type, List.of(defaultValue));
     }
 
-    public <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argMany(String name, ArgumentType<T> type, Supplier<List<T>> empty) {
-        return argMany(name, RepeatArgumentType.some(type, ARGUMENT_EXPECTED), empty);
-    }
-
-    public <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argManyFlatten(String name, ArgumentType<List<T>> type, Supplier<List<T>> empty) {
-        return argMany(name, RepeatArgumentType.someFlat(type, ARGUMENT_EXPECTED), empty);
-    }
-
-    private <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argMany(String name, RepeatArgumentType<T, ?> type, Supplier<List<T>> empty) {
+    private <T> CommandNodeBuilder<S, ArgCommand<S, List<T>>> argMany(String name, RepeatArgumentType<T> type, List<T> empty) {
         if (args.isEmpty()) throw new IllegalStateException("Cannot have empty arg chain builder");
 
         return command -> {
             // The node for no arguments
-            var tail = setupTail(ctx -> command.run(ctx, empty.get()));
+            var tail = setupTail(ctx -> command.run(ctx, empty));
 
             // The node for one or more arguments
             ArgumentBuilder<S, ?> moreArg = RequiredArgumentBuilder
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/config/AddressRuleConfig.java b/projects/common/src/main/java/dan200/computercraft/shared/config/AddressRuleConfig.java
index 3cc27039a..9ac8347c4 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/config/AddressRuleConfig.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/config/AddressRuleConfig.java
@@ -148,13 +148,14 @@ class AddressRuleConfig {
     }
 
     private static <T extends Enum<T>> T parseEnum(String field, Class<T> klass, String x) {
-        for (var value : klass.getEnumConstants()) {
+        var values = Objects.requireNonNull(klass.getEnumConstants());
+        for (var value : values) {
             if (value.name().equalsIgnoreCase(x)) return value;
         }
 
         throw new InvalidRuleException(String.format(
             "Field '%s' should be one of %s, but is '%s'.",
-            field, Arrays.stream(klass.getEnumConstants()).map(Enum::name).toList(), x
+            field, Arrays.stream(values).map(Enum::name).toList(), x
         ));
     }
 }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDriveBlockEntity.java b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDriveBlockEntity.java
index ba6d987b7..f8ae87455 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDriveBlockEntity.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDriveBlockEntity.java
@@ -81,7 +81,7 @@ public final class DiskDriveBlockEntity extends AbstractContainerBlockEntity imp
     private boolean recordPlaying = false;
     // In order to avoid main-thread calls in the peripheral, we set flags to mark which operation should be performed,
     // then read them when ticking.
-    private final AtomicReference<RecordCommand> recordQueued = new AtomicReference<>(null);
+    private final AtomicReference<@Nullable RecordCommand> recordQueued = new AtomicReference<>(null);
     private final AtomicBoolean ejectQueued = new AtomicBoolean(false);
 
     /**
@@ -172,7 +172,7 @@ public final class DiskDriveBlockEntity extends AbstractContainerBlockEntity imp
      */
     private synchronized void updateMedia() {
         var newStack = getDiskStack();
-        if (ItemStack.isSameItemSameComponents(newStack, media.stack())) return;
+        if (ItemStack.matches(newStack, media.stack())) return;
 
         var newMedia = MediaStack.of(newStack);
 
@@ -243,7 +243,7 @@ public final class DiskDriveBlockEntity extends AbstractContainerBlockEntity imp
      */
     @GuardedBy("this")
     private void updateMediaStack(ItemStack stack, boolean immediate) {
-        if (ItemStack.isSameItemSameComponents(media.stack(), stack)) return;
+        if (ItemStack.matches(media.stack(), stack)) return;
         media = new MediaStack(stack, media.media());
 
         if (immediate) {
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java
index ce978718c..0a69c750f 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java
@@ -10,6 +10,7 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.core.methods.PeripheralMethod;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A {@link PeripheralMethod} along with the method's target.
@@ -34,7 +35,7 @@ final class SaturatedMethod {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@Nullable Object obj) {
         if (obj == this) return true;
         if (!(obj instanceof SaturatedMethod other)) return false;
 
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java
index 7370b76be..031a402eb 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java
@@ -389,7 +389,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         public synchronized @Nullable String mount(String desiredLocation, Mount mount) {
             if (!attached) throw new NotAttachedException();
             var mounted = computer.mount(desiredLocation, mount, name);
-            mounts.add(mounted);
+            if (mounted != null) mounts.add(mounted);
             return mounted;
         }
 
@@ -397,7 +397,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         public synchronized @Nullable String mount(String desiredLocation, Mount mount, String driveName) {
             if (!attached) throw new NotAttachedException();
             var mounted = computer.mount(desiredLocation, mount, driveName);
-            mounts.add(mounted);
+            if (mounted != null) mounts.add(mounted);
             return mounted;
         }
 
@@ -405,7 +405,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         public synchronized @Nullable String mountWritable(String desiredLocation, WritableMount mount) {
             if (!attached) throw new NotAttachedException();
             var mounted = computer.mountWritable(desiredLocation, mount, name);
-            mounts.add(mounted);
+            if (mounted != null) mounts.add(mounted);
             return mounted;
         }
 
@@ -413,7 +413,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         public synchronized @Nullable String mountWritable(String desiredLocation, WritableMount mount, String driveName) {
             if (!attached) throw new NotAttachedException();
             var mounted = computer.mountWritable(desiredLocation, mount, driveName);
-            mounts.add(mounted);
+            if (mounted != null) mounts.add(mounted);
             return mounted;
         }
 
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/CopyComponents.java b/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/CopyComponents.java
index 9eaad2b63..6834acef5 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/CopyComponents.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/CopyComponents.java
@@ -78,7 +78,7 @@ public final class CopyComponents implements RecipeFunction {
     }
 
     @Override
-    public Type<?> getType() {
+    public Type<CopyComponents> getType() {
         return ModRegistry.RecipeFunctions.COPY_COMPONENTS.get();
     }
 
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/RecipeFunction.java b/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/RecipeFunction.java
index ae4ebe767..4a4aaa21d 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/RecipeFunction.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/recipe/function/RecipeFunction.java
@@ -39,7 +39,7 @@ public interface RecipeFunction {
     /**
      * The registry where {@link RecipeFunction}s are registered.
      */
-    ResourceKey<Registry<Type<?>>> REGISTRY = ResourceKey.createRegistryKey(ResourceLocation.fromNamespaceAndPath(ComputerCraftAPI.MOD_ID, "recipe_function"));
+    ResourceKey<Registry<Type<? extends RecipeFunction>>> REGISTRY = ResourceKey.createRegistryKey(ResourceLocation.fromNamespaceAndPath(ComputerCraftAPI.MOD_ID, "recipe_function"));
 
     /**
      * The codec to read and write {@link RecipeFunction}s with.
@@ -66,7 +66,7 @@ public interface RecipeFunction {
      *
      * @return The type of this recipe function.
      */
-    Type<?> getType();
+    Type<? extends RecipeFunction> getType();
 
     /**
      * Apply this recipe function, modifying the result item.
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java b/projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java
index b0ed63617..f1d3e415d 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java
@@ -740,7 +740,7 @@ public class TurtleBrain implements TurtleAccessInternal {
         }
 
         @Override
-        public MethodResult resume(Object[] response) {
+        public MethodResult resume(@Nullable Object[] response) {
             if (response.length < 3 || !(response[1] instanceof Number id) || !(response[2] instanceof Boolean)) {
                 return pull;
             }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeContainer.java b/projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeContainer.java
index 7d63770d0..a39783ca7 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeContainer.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeContainer.java
@@ -29,7 +29,7 @@ class UpgradeContainer implements Container {
 
     private final ITurtleAccess turtle;
 
-    private final List<UpgradeData<ITurtleUpgrade>> lastUpgrade = Arrays.asList(null, null);
+    private final List<@Nullable UpgradeData<ITurtleUpgrade>> lastUpgrade = Arrays.asList(null, null);
     private final NonNullList<ItemStack> lastStack = NonNullList.withSize(2, ItemStack.EMPTY);
 
     UpgradeContainer(ITurtleAccess turtle) {
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java b/projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java
index 4cf392439..802d35b46 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java
@@ -108,7 +108,7 @@ public class TurtleTool extends AbstractTurtleUpgrade.StackAware {
         if (!getCraftingIngredient().test(stack) || !isItemSuitable(stack)) return;
 
         // Early return if the item hasn't changed to avoid redundant syncs with the client.
-        if (ItemStack.isSameItemSameComponents(stack, oldStack)) return;
+        if (ItemStack.matches(stack, oldStack)) return;
 
         upgrade.setItem(stack);
     }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/util/IDAssigner.java b/projects/common/src/main/java/dan200/computercraft/shared/util/IDAssigner.java
index d2d3408eb..04f892537 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/util/IDAssigner.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/util/IDAssigner.java
@@ -22,6 +22,7 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.*;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 public final class IDAssigner {
     private static final Logger LOG = LoggerFactory.getLogger(IDAssigner.class);
@@ -83,7 +84,7 @@ public final class IDAssigner {
             }
         } else {
             try {
-                Files.createDirectories(idFile.getParent());
+                Files.createDirectories(Objects.requireNonNull(idFile.getParent()));
             } catch (IOException e) {
                 LOG.error("Cannot create owning directory, IDs will not be persisted", e);
             }
diff --git a/projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java b/projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java
index b4f65ceef..1d472de8e 100644
--- a/projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java
+++ b/projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java
@@ -51,15 +51,7 @@ public final class NBTUtil {
             case Tag.TAG_BYTE, Tag.TAG_SHORT, Tag.TAG_INT, Tag.TAG_LONG -> ((NumericTag) tag).getAsLong();
             case Tag.TAG_FLOAT, Tag.TAG_DOUBLE -> ((NumericTag) tag).getAsDouble();
             case Tag.TAG_STRING -> tag.getAsString();
-            case Tag.TAG_COMPOUND -> {
-                var compound = (CompoundTag) tag;
-                Map<String, Object> map = new HashMap<>(compound.size());
-                for (var key : compound.getAllKeys()) {
-                    var value = toLua(compound.get(key));
-                    if (value != null) map.put(key, value);
-                }
-                yield map;
-            }
+            case Tag.TAG_COMPOUND -> toLua((CompoundTag) tag);
             case Tag.TAG_LIST -> ((ListTag) tag).stream().map(NBTUtil::toLua).toList();
             case Tag.TAG_BYTE_ARRAY -> {
                 var array = ((ByteArrayTag) tag).getAsByteArray();
@@ -73,6 +65,15 @@ public final class NBTUtil {
         };
     }
 
+    public static Map<String, Object> toLua(CompoundTag tag) {
+        Map<String, Object> map = new HashMap<>(tag.size());
+        for (var key : tag.getAllKeys()) {
+            var value = toLua(tag.get(key));
+            if (value != null) map.put(key, value);
+        }
+        return map;
+    }
+
     @Nullable
     public static String getNBTHash(@Nullable Tag tag) {
         if (tag == null) return null;
diff --git a/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/ItemStackMatcher.java b/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/ItemStackMatcher.java
index 9cf1df753..84b21c0c1 100644
--- a/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/ItemStackMatcher.java
+++ b/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/ItemStackMatcher.java
@@ -19,7 +19,7 @@ public class ItemStackMatcher extends TypeSafeMatcher<ItemStack> {
 
     @Override
     protected boolean matchesSafely(ItemStack item) {
-        return ItemStack.isSameItemSameComponents(item, stack) && item.getCount() == stack.getCount();
+        return ItemStack.matches(item, stack);
     }
 
     @Override
diff --git a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Recipe_Test.kt b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Recipe_Test.kt
index 327164c0a..a1372dc40 100644
--- a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Recipe_Test.kt
+++ b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Recipe_Test.kt
@@ -118,7 +118,7 @@ class Recipe_Test {
             for (recipe in recipes) {
                 // Ensure the result matches the input.
                 val result = recipe.getResultItem(context.level.registryAccess())
-                if (!ItemStack.isSameItemSameComponents(result, item) || result.count != item.count) {
+                if (!ItemStack.matches(result, item)) {
                     context.fail("Expected to craft ${item.toStringFull()} but crafted ${result.toStringFull()}")
                 }
 
diff --git a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/api/TestExtensions.kt b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/api/TestExtensions.kt
index 54481f368..ccf32d893 100644
--- a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/api/TestExtensions.kt
+++ b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/api/TestExtensions.kt
@@ -377,7 +377,7 @@ fun GameTestHelper.assertCraftable(items: List<ItemStack>, result: ItemStack, wi
 
     val actualResult = recipe.get().value.assemble(input, level.registryAccess())
 
-    if (!ItemStack.isSameItemSameComponents(actualResult, result) || actualResult.count != result.count) {
+    if (!ItemStack.matches(actualResult, result)) {
         fail("Expected $items to craft ${result.toStringFull()}, got ${actualResult.toStringFull()}")
     }
 }
diff --git a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestHooks.kt b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestHooks.kt
index 9980c65fb..aaec3e026 100644
--- a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestHooks.kt
+++ b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestHooks.kt
@@ -48,7 +48,7 @@ object TestHooks {
     var structureManager: StructureTemplateManager? = null
 
     @JvmStatic
-    fun init() {
+    fun init(loader: String) {
         ServerContext.luaMachine = ManagedComputers
         ComputerCraftAPI.registerAPIFactory(::TestAPI)
         StructureUtils.testStructuresDir = sourceDir.resolve("structures").toString()
@@ -59,7 +59,7 @@ object TestHooks {
             try {
                 GlobalTestReporter.replaceWith(
                     MultiTestReporter(
-                        JunitTestReporter(File(outputPath)),
+                        OtrTestReporter("$loader gametests", File(outputPath)),
                         LogTestReporter(),
                     ),
                 )
diff --git a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestReporters.kt b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestReporters.kt
index 94dab5d1d..8eeaf5200 100644
--- a/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestReporters.kt
+++ b/projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestReporters.kt
@@ -4,22 +4,19 @@
 
 package dan200.computercraft.gametest.core
 
-import com.google.common.base.Stopwatch
 import net.minecraft.gametest.framework.GameTestInfo
-import net.minecraft.gametest.framework.JUnitLikeTestReporter
 import net.minecraft.gametest.framework.TestReporter
-import org.w3c.dom.Document
-import org.w3c.dom.Element
-import java.io.*
-import java.nio.file.Files.createDirectories
+import org.opentest4j.reporting.events.api.DocumentWriter
+import org.opentest4j.reporting.events.api.NamespaceRegistry
+import org.opentest4j.reporting.events.core.CoreFactory
+import org.opentest4j.reporting.events.java.JavaFactory
+import org.opentest4j.reporting.events.root.Events
+import org.opentest4j.reporting.events.root.Finished
+import org.opentest4j.reporting.events.root.RootFactory
+import org.opentest4j.reporting.schema.Namespace
+import java.io.File
 import java.time.Instant
-import java.time.format.DateTimeFormatter
-import java.util.concurrent.TimeUnit
-import javax.xml.parsers.DocumentBuilderFactory
-import javax.xml.transform.TransformerException
-import javax.xml.transform.TransformerFactory
-import javax.xml.transform.dom.DOMSource
-import javax.xml.transform.stream.StreamResult
+import org.opentest4j.reporting.events.core.Result as OtrResult
 
 /**
  * A test reporter which delegates to a list of other reporters.
@@ -41,74 +38,62 @@ class MultiTestReporter(private val reporters: List<TestReporter>) : TestReporte
 }
 
 /**
- * Reports tests to a JUnit XML file. This is equivalent to [JUnitLikeTestReporter], except it ensures the destination
- * directory exists and includes the stack trace in the error.
+ * A test reporter that writes [Open Test Reporting](https://github.com/ota4j-team/open-test-reporting/) test reports.
+ *
+ * @param name The name of this test suite.
+ * @param destination The destination file to write to.
  */
-open class JunitTestReporter(private val destination: File) : TestReporter {
-    private val document: Document
-    private val testSuite: Element
-    private val stopwatch: Stopwatch = Stopwatch.createStarted()
+class OtrTestReporter(name: String, destination: File) : TestReporter {
+    private val writer: DocumentWriter<Events>
+    private var hasErrors = false
 
     init {
-        document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument()
+        val namespaceRegistry = NamespaceRegistry.builder(Namespace.REPORTING_CORE)
+            .add("e", Namespace.REPORTING_EVENTS)
+            .add("java", Namespace.REPORTING_JAVA)
+            .build()
 
-        testSuite = document.createElement("testsuite")
-        testSuite.setAttribute("timestamp", DateTimeFormatter.ISO_INSTANT.format(Instant.now()))
+        writer = Events.createDocumentWriter(namespaceRegistry, destination.toPath())
 
-        val container = document.createElement("testsuite")
-        container.appendChild(testSuite)
-        document.appendChild(container)
+        writer.append(RootFactory.started(SUITE_ID, Instant.now(), name))
     }
 
-    private fun createTestCase(testInfo: GameTestInfo, name: String?): Element {
-        val testCase = document.createElement("testcase")
-        testCase.setAttribute("name", name)
-        testCase.setAttribute("classname", testInfo.structureName)
-        testCase.setAttribute("time", (testInfo.runTime.toDouble() / 1000.0).toString())
-        testSuite.appendChild(testCase)
-        return testCase
+    private fun report(testInfo: GameTestInfo, configure: (Finished) -> Unit) {
+        val finished = Instant.now()
+        val started = finished.minusMillis(testInfo.runTime)
+        writer.append(RootFactory.started(testInfo.testName, started, testInfo.testName)) {
+            it.withParentId(SUITE_ID)
+        }
+        writer.append(RootFactory.finished(testInfo.testName, finished), configure)
     }
 
     override fun onTestFailed(testInfo: GameTestInfo) {
-        val error = testInfo.error!!
-        val result: Element
-        if (testInfo.isRequired) {
-            result = document.createElement("failure")
-            result.setAttribute("message", error.message)
-            result.setAttribute("type", error.javaClass.name)
+        report(testInfo) { report ->
+            if (testInfo.isRequired) hasErrors = true
 
-            val writer = StringWriter()
-            error.printStackTrace(PrintWriter(writer))
-            result.textContent = writer.toString()
-        } else {
-            result = document.createElement("skipped")
-            result.setAttribute("message", error.message)
+            val status = if (testInfo.isRequired) OtrResult.Status.FAILED else OtrResult.Status.ABORTED
+            report.append(CoreFactory.result(status)) { result ->
+                val error = testInfo.error
+                if (error != null) {
+                    result.append(CoreFactory.reason(error.message ?: "unknown"))
+                    result.append(JavaFactory.throwable(error))
+                }
+            }
         }
-
-        createTestCase(testInfo, testInfo.testName).appendChild(result)
     }
 
     override fun onTestSuccess(testInfo: GameTestInfo) {
-        createTestCase(testInfo, testInfo.testName)
+        report(testInfo) { it.append(CoreFactory.result(OtrResult.Status.SUCCESSFUL)) }
     }
 
     override fun finish() {
-        stopwatch.stop()
-        testSuite.setAttribute(
-            "time",
-            (stopwatch.elapsed(TimeUnit.MILLISECONDS).toDouble() / 1000.0).toString(),
-        )
-
-        try {
-            try {
-                createDirectories(destination.toPath().parent)
-            } catch (e: IOException) {
-                throw UncheckedIOException("Failed to create parent directory", e)
-            }
-
-            TransformerFactory.newInstance().newTransformer().transform(DOMSource(document), StreamResult(destination))
-        } catch (transformerException: TransformerException) {
-            throw Error("Couldn't save test report", transformerException)
+        writer.append(RootFactory.finished(SUITE_ID, Instant.now())) {
+            it.append(CoreFactory.result(if (hasErrors) OtrResult.Status.FAILED else OtrResult.Status.SUCCESSFUL))
         }
+        writer.close()
+    }
+
+    companion object {
+        private const val SUITE_ID = "_gametests_"
     }
 }
diff --git a/projects/core/src/main/java/dan200/computercraft/core/apis/OSAPI.java b/projects/core/src/main/java/dan200/computercraft/core/apis/OSAPI.java
index b68718648..3726e66e4 100644
--- a/projects/core/src/main/java/dan200/computercraft/core/apis/OSAPI.java
+++ b/projects/core/src/main/java/dan200/computercraft/core/apis/OSAPI.java
@@ -8,7 +8,6 @@ import dan200.computercraft.api.lua.IArguments;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.LuaFunction;
-import dan200.computercraft.core.util.Nullability;
 import dan200.computercraft.core.util.StringUtil;
 import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
@@ -430,7 +429,7 @@ public class OSAPI implements ILuaAPI {
     @LuaFunction
     public final Object date(Optional<String> formatA, Optional<Long> timeA) throws LuaException {
         var format = formatA.orElse("%c");
-        long time = Nullability.assertNonNull(timeA.orElseGet(() -> Instant.now().getEpochSecond()));
+        long time = timeA.orElseGet(() -> Instant.now().getEpochSecond());
 
         var instant = Instant.ofEpochSecond(time);
         ZonedDateTime date;
diff --git a/projects/core/src/main/java/dan200/computercraft/core/apis/http/Resource.java b/projects/core/src/main/java/dan200/computercraft/core/apis/http/Resource.java
index 6173dc8f2..791b0445f 100644
--- a/projects/core/src/main/java/dan200/computercraft/core/apis/http/Resource.java
+++ b/projects/core/src/main/java/dan200/computercraft/core/apis/http/Resource.java
@@ -86,7 +86,6 @@ public abstract class Resource<R extends Resource<R, S>, S extends Resource.Reso
         return state.lock();
     }
 
-    @SuppressWarnings("NullAway") // FIXME: NullAway doesn't support generics.
     @CheckReturnValue
     private boolean setState(LockedReference.ReadWriteHandle<@Nullable S> stateHandle, @Nullable S newState) {
         var oldState = stateHandle.get();
diff --git a/projects/core/src/main/java/dan200/computercraft/core/lua/VarargArguments.java b/projects/core/src/main/java/dan200/computercraft/core/lua/VarargArguments.java
index 095b51bda..c0e398bc5 100644
--- a/projects/core/src/main/java/dan200/computercraft/core/lua/VarargArguments.java
+++ b/projects/core/src/main/java/dan200/computercraft/core/lua/VarargArguments.java
@@ -27,7 +27,7 @@ final class VarargArguments implements IArguments {
     private volatile boolean closed;
     private final VarargArguments root;
 
-    private @Nullable ArraySlice<Object> cache;
+    private @Nullable ArraySlice<@Nullable Object> cache;
     private @Nullable ArraySlice<String> typeNames;
 
     private boolean escapes;
@@ -230,14 +230,12 @@ final class VarargArguments implements IArguments {
     }
 
     @SuppressWarnings("ArrayRecordComponent")
-    private record ArraySlice<T>(@Nullable T[] array, int offset) {
-        // FIXME: We should be able to remove the @Nullables if we update NullAway.
-
-        @Nullable T get(int index) {
+    private record ArraySlice<T extends @Nullable Object>(T[] array, int offset) {
+        T get(int index) {
             return array[offset + index];
         }
 
-        void set(int index, @Nullable T value) {
+        void set(int index, T value) {
             array[offset + index] = value;
         }
 
diff --git a/projects/fabric/src/main/java/dan200/computercraft/shared/platform/FabricConfigFile.java b/projects/fabric/src/main/java/dan200/computercraft/shared/platform/FabricConfigFile.java
index a297fb251..4ef73f4ca 100644
--- a/projects/fabric/src/main/java/dan200/computercraft/shared/platform/FabricConfigFile.java
+++ b/projects/fabric/src/main/java/dan200/computercraft/shared/platform/FabricConfigFile.java
@@ -10,7 +10,6 @@ import com.electronwill.nightconfig.core.file.FileNotFoundAction;
 import com.electronwill.nightconfig.core.file.FileWatcher;
 import com.electronwill.nightconfig.core.io.WritingMode;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
-import dan200.computercraft.core.util.Nullability;
 import dan200.computercraft.shared.config.ConfigFile;
 import org.apache.commons.lang3.function.TriFunction;
 import org.jspecify.annotations.Nullable;
@@ -59,7 +58,7 @@ public final class FabricConfigFile extends ConfigFile {
 
         closeConfig();
 
-        var path = Nullability.assertNonNull(Arrays.stream(paths).filter(Files::exists).findFirst().orElseGet(() -> paths[paths.length - 1]));
+        var path = Arrays.stream(paths).filter(Files::exists).findFirst().orElseGet(() -> paths[paths.length - 1]);
         var config = this.config = CommentedFileConfig.builder(path).sync()
             .onFileNotFound(FileNotFoundAction.READ_NOTHING)
             .writingMode(WritingMode.REPLACE)
diff --git a/projects/fabric/src/main/java/dan200/computercraft/shared/platform/PlatformHelperImpl.java b/projects/fabric/src/main/java/dan200/computercraft/shared/platform/PlatformHelperImpl.java
index 4bee39bf5..673649a8a 100644
--- a/projects/fabric/src/main/java/dan200/computercraft/shared/platform/PlatformHelperImpl.java
+++ b/projects/fabric/src/main/java/dan200/computercraft/shared/platform/PlatformHelperImpl.java
@@ -246,7 +246,6 @@ public class PlatformHelperImpl implements PlatformHelper {
     }
 
     @Override
-    @SuppressWarnings("NullAway") // NullAway doesn't like the null here.
     public @Nullable IMedia getMedia(ItemStack stack) {
         return MediaLookup.get().find(stack, null);
     }
diff --git a/projects/fabric/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java b/projects/fabric/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
index bca5f21f6..8f157e32a 100644
--- a/projects/fabric/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
+++ b/projects/fabric/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
@@ -21,7 +21,7 @@ import net.minecraft.resources.ResourceLocation;
 public class TestMod implements ModInitializer, ClientModInitializer {
     @Override
     public void onInitialize() {
-        TestHooks.init();
+        TestHooks.init("Fabric");
 
         var phase = ResourceLocation.fromNamespaceAndPath(ComputerCraftAPI.MOD_ID, "test_mod");
         ServerLifecycleEvents.SERVER_STARTED.addPhaseOrdering(Event.DEFAULT_PHASE, phase);
diff --git a/projects/forge/build.gradle.kts b/projects/forge/build.gradle.kts
index 02b09919b..4353871ca 100644
--- a/projects/forge/build.gradle.kts
+++ b/projects/forge/build.gradle.kts
@@ -214,6 +214,7 @@ dependencies {
     // Ensure our test fixture dependencies are on the classpath
     "testAdditionalRuntimeClasspath"(libs.bundles.kotlin)
     "testAdditionalRuntimeClasspath"(libs.bundles.test)
+    "testAdditionalRuntimeClasspath"(libs.openTestReporting)
 
     "testWithIris"(libs.iris.forge)
     "testWithIris"(libs.sodium.forge)
diff --git a/projects/forge/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java b/projects/forge/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
index bb541a94e..539020c2f 100644
--- a/projects/forge/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
+++ b/projects/forge/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java
@@ -22,7 +22,7 @@ import net.neoforged.neoforge.event.tick.ServerTickEvent;
 @Mod("cctest")
 public class TestMod {
     public TestMod(IEventBus modBus) {
-        TestHooks.init();
+        TestHooks.init("Forge");
 
         var bus = NeoForge.EVENT_BUS;
         bus.addListener(EventPriority.LOW, (ServerStartedEvent e) -> TestHooks.onServerStarted(e.getServer()));
diff --git a/projects/web/src/builder/java/cc/tweaked/web/builder/Builder.java b/projects/web/src/builder/java/cc/tweaked/web/builder/Builder.java
index c43c1661a..3f741d565 100644
--- a/projects/web/src/builder/java/cc/tweaked/web/builder/Builder.java
+++ b/projects/web/src/builder/java/cc/tweaked/web/builder/Builder.java
@@ -72,7 +72,7 @@ public class Builder {
 
         // Then finally start the compiler!
         run(output, remapper, TeaVMTargetType.JAVASCRIPT, TeaVMOptimizationLevel.ADVANCED, minify);
-        run(output, remapper, TeaVMTargetType.WEBASSEMBLY_GC, TeaVMOptimizationLevel.SIMPLE, minify);
+        run(output, remapper, TeaVMTargetType.WEBASSEMBLY_GC, TeaVMOptimizationLevel.ADVANCED, minify);
 
         try (var runtime = Objects.requireNonNull(Builder.class.getClassLoader()).getResourceAsStream("org/teavm/backend/wasm/wasm-gc-module-runtime.js")) {
             if (runtime == null) throw new IllegalStateException("Cannot find WASM runtime");
diff --git a/projects/web/src/main/java/cc/tweaked/web/http/HttpRequest.java b/projects/web/src/main/java/cc/tweaked/web/http/HttpRequest.java
index 03d3cb5c3..512d91d93 100644
--- a/projects/web/src/main/java/cc/tweaked/web/http/HttpRequest.java
+++ b/projects/web/src/main/java/cc/tweaked/web/http/HttpRequest.java
@@ -5,7 +5,11 @@
 package cc.tweaked.web.http;
 
 import cc.tweaked.web.Main;
-import com.google.common.base.Splitter;
+import cc.tweaked.web.js.Console;
+import cc.tweaked.web.js.abort.AbortController;
+import cc.tweaked.web.js.fetch.Headers;
+import cc.tweaked.web.js.fetch.RequestInit;
+import cc.tweaked.web.js.fetch.Response;
 import dan200.computercraft.core.Logging;
 import dan200.computercraft.core.apis.IAPIEnvironment;
 import dan200.computercraft.core.apis.handles.ArrayByteChannel;
@@ -20,8 +24,10 @@ import io.netty.handler.codec.http.HttpMethod;
 import org.jspecify.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.teavm.jso.JSObject;
 import org.teavm.jso.ajax.XMLHttpRequest;
-import org.teavm.jso.typedarrays.ArrayBuffer;
+import org.teavm.jso.core.JSError;
+import org.teavm.jso.core.JSPromise;
 import org.teavm.jso.typedarrays.Int8Array;
 
 import java.nio.ByteBuffer;
@@ -74,10 +80,10 @@ final class HttpRequest extends Resource<HttpRequest, HttpRequest.State> {
         }
     }
 
-    private record Fetching(XMLHttpRequest request) implements State {
+    private record Fetching(AbortController abort) implements State {
         @Override
         public void close() {
-            request.abort();
+            abort.abort();
         }
     }
 
@@ -88,18 +94,31 @@ final class HttpRequest extends Resource<HttpRequest, HttpRequest.State> {
 
     private @Nullable State doRequest(HttpUri uri, HttpMethod method) {
         try {
-            var request = new XMLHttpRequest();
-            request.setOnReadyStateChange(() -> onResponseStateChange(request));
-            request.setResponseType("arraybuffer");
-            var address = uri.getUri().toASCIIString();
-            request.open(method.toString(), Main.CORS_PROXY.isEmpty() ? address : Main.CORS_PROXY.replace("{}", address));
+            var abort = new AbortController();
+
+            var request = RequestInit.create();
+            request.setMethod(method.name());
+            if (postBuffer != null) request.setBody(Int8Array.fromJavaBuffer(postBuffer));
+            request.setSignal(abort.getSignal());
+
+            var requestHeaders = new Headers();
             for (var iterator = headers.iteratorAsString(); iterator.hasNext(); ) {
                 var header = iterator.next();
-                request.setRequestHeader(header.getKey(), header.getValue());
+                requestHeaders.append(header.getKey(), header.getValue());
             }
-            request.setRequestHeader("X-CC-Redirect", followRedirects ? "true" : "false");
-            request.send(postBuffer == null ? null : Int8Array.fromJavaBuffer(postBuffer));
-            return new Fetching(request);
+            requestHeaders.append("X-CC-Redirect", Boolean.toString(followRedirects));
+
+            var address = uri.getUri().toASCIIString();
+            Response.fetch(Main.CORS_PROXY.isEmpty() ? address : Main.CORS_PROXY.replace("{}", address), request)
+                .then(this::handleResponse)
+                .catchError(e -> {
+                    if (e instanceof JSError err) Console.error(err);
+                    LOG.error(Logging.HTTP_ERROR, "Error in HTTP request", e);
+                    close(Fetching.class, () -> queueFailure("Could not connect"));
+                    return null;
+                });
+
+            return new Fetching(abort);
         } catch (Exception e) {
             LOG.error(Logging.HTTP_ERROR, "Error in HTTP request", e);
             queueFailure("Could not connect");
@@ -107,39 +126,39 @@ final class HttpRequest extends Resource<HttpRequest, HttpRequest.State> {
         }
     }
 
-    private void onResponseStateChange(XMLHttpRequest request) {
-        if (request.getReadyState() != XMLHttpRequest.DONE) return;
-        if (request.getStatus() == 0) {
+    private @Nullable JSPromise<? extends @Nullable JSObject> handleResponse(Response response) {
+        if (response.getStatus() == 0) {
             close(Fetching.class, () -> queueFailure("Could not connect"));
-            return;
+            return null;
         }
 
-        var buffer = (ArrayBuffer) request.getResponse();
-        SeekableByteChannel contents = new ArrayByteChannel(new Int8Array(buffer).copyToJavaArray());
-        var reader = new ReadHandle(contents, binary);
-
         Map<String, String> responseHeaders = new HashMap<>();
-        for (var header : Splitter.on("\r\n").split(request.getAllResponseHeaders())) {
-            var index = header.indexOf(':');
-            if (index < 0) continue;
-
+        response.getHeaders().forEach((v, k, h) -> {
             // Normalise the header (so "content-type" becomes "Content-Type")
             var upcase = true;
-            var headerBuilder = new StringBuilder(index);
-            for (var i = 0; i < index; i++) {
-                var c = header.charAt(i);
+            var headerBuilder = new StringBuilder(k.length());
+            for (var i = 0; i < k.length(); i++) {
+                var c = k.charAt(i);
                 headerBuilder.append(upcase ? Character.toUpperCase(c) : c);
                 upcase = c == '-';
             }
-            responseHeaders.put(headerBuilder.toString(), header.substring(index + 1).trim());
-        }
-        var stream = new HttpResponseHandle(reader, request.getStatus(), request.getStatusText(), responseHeaders);
+            responseHeaders.put(headerBuilder.toString(), v);
+        });
 
-        if (request.getStatus() >= 200 && request.getStatus() < 400) {
-            close(Fetching.class, () -> environment.queueEvent(SUCCESS_EVENT, address, stream));
-        } else {
-            close(Fetching.class, () -> environment.queueEvent(FAILURE_EVENT, address, request.getStatusText(), stream));
-        }
+        return response.bytes().then(body -> {
+            SeekableByteChannel contents = new ArrayByteChannel(new Int8Array(body).copyToJavaArray());
+            var reader = new ReadHandle(contents, binary);
+
+            var stream = new HttpResponseHandle(reader, response.getStatus(), response.getStatusText(), responseHeaders);
+
+            if (response.getStatus() >= 200 && response.getStatus() < 400) {
+                close(Fetching.class, () -> environment.queueEvent(SUCCESS_EVENT, address, stream));
+            } else {
+                close(Fetching.class, () -> environment.queueEvent(FAILURE_EVENT, address, response.getStatusText(), stream));
+            }
+
+            return null;
+        });
     }
 
     private void queueFailure(String message) {
diff --git a/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortController.java b/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortController.java
new file mode 100644
index 000000000..911f69b87
--- /dev/null
+++ b/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortController.java
@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2026 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.web.js.abort;
+
+import org.teavm.jso.JSClass;
+import org.teavm.jso.JSObject;
+import org.teavm.jso.JSProperty;
+
+/**
+ * The {@link AbortController} interface represents a controller object that allows you to abort one or more Web
+ * requests as and when desired.
+ *
+ * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/AbortController">MDN Reference</a>
+ */
+@JSClass
+public class AbortController implements JSObject {
+    public AbortController() {
+    }
+
+    @JSProperty
+    public native AbortSignal getSignal();
+
+    public native void abort();
+
+    public native void abort(String reason);
+
+    public native void abort(JSObject reason);
+}
diff --git a/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortSignal.java b/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortSignal.java
new file mode 100644
index 000000000..9b292e9b9
--- /dev/null
+++ b/projects/web/src/main/java/cc/tweaked/web/js/abort/AbortSignal.java
@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: 2026 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.web.js.abort;
+
+import org.teavm.jso.JSObject;
+import org.teavm.jso.JSProperty;
+import org.teavm.jso.dom.events.EventTarget;
+
+/**
+ * The {@link AbortSignal} interface represents a signal object that allows you to communicate with an asynchronous
+ * operation (such as a fetch request) and abort it if required via an {@link AbortController} object.
+ *
+ * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal">MDN Reference</a>
+ */
+public interface AbortSignal extends EventTarget {
+    @JSProperty
+    boolean getAborted();
+
+    @JSProperty
+    JSObject getReason();
+}
diff --git a/projects/web/src/main/java/cc/tweaked/web/js/fetch/Headers.java b/projects/web/src/main/java/cc/tweaked/web/js/fetch/Headers.java
new file mode 100644
index 000000000..5efed587c
--- /dev/null
+++ b/projects/web/src/main/java/cc/tweaked/web/js/fetch/Headers.java
@@ -0,0 +1,29 @@
+// SPDX-FileCopyrightText: 2026 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.web.js.fetch;
+
+import org.teavm.jso.JSClass;
+import org.teavm.jso.JSFunctor;
+import org.teavm.jso.JSObject;
+
+/**
+ * The {@link Headers} interface of the Fetch API allows you to perform various actions on HTTP request and response
+ * headers. These actions include retrieving, setting, adding to, and removing headers from the list of the request's
+ * headers.
+ *
+ * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/Headers">MDN Reference</a>
+ */
+@JSClass
+public class Headers implements JSObject {
+    public native void append(String key, String value);
+
+    public native void forEach(ForEachConsumer consumer);
+
+    @JSFunctor
+    @FunctionalInterface
+    public interface ForEachConsumer extends JSObject {
+        void accept(String value, String key, Headers object);
+    }
+}
diff --git a/projects/web/src/main/java/cc/tweaked/web/js/fetch/RequestInit.java b/projects/web/src/main/java/cc/tweaked/web/js/fetch/RequestInit.java
new file mode 100644
index 000000000..a017a96c2
--- /dev/null
+++ b/projects/web/src/main/java/cc/tweaked/web/js/fetch/RequestInit.java
@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2026 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.web.js.fetch;
+
+import cc.tweaked.web.js.abort.AbortSignal;
+import org.teavm.jso.JSClass;
+import org.teavm.jso.JSObject;
+import org.teavm.jso.JSProperty;
+import org.teavm.jso.core.JSMapLike;
+import org.teavm.jso.core.JSObjects;
+import org.teavm.jso.typedarrays.ArrayBuffer;
+import org.teavm.jso.typedarrays.TypedArray;
+
+/**
+ * The properties that can be passed to {@link Response#fetch(String, RequestInit)}.
+ *
+ * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/RequestInit">MDN Reference</a>
+ */
+@JSClass(transparent = true)
+public abstract class RequestInit implements JSObject {
+    private RequestInit() {
+    }
+
+    public static RequestInit create() {
+        return JSObjects.create();
+    }
+
+    @JSProperty
+    public native void setMethod(String method);
+
+    @JSProperty
+    public native void setBody(String type);
+
+    @JSProperty
+    public native void setBody(ArrayBuffer body);
+
+    @JSProperty
+    public native void setBody(TypedArray body);
+
+    @JSProperty
+    public native void setHeaders(Headers headers);
+
+    @JSProperty
+    public native void setHeaders(JSMapLike<String> headers);
+
+    @JSProperty
+    public native void setSignal(AbortSignal signal);
+}
diff --git a/projects/web/src/main/java/cc/tweaked/web/js/fetch/Response.java b/projects/web/src/main/java/cc/tweaked/web/js/fetch/Response.java
new file mode 100644
index 000000000..788bfd2be
--- /dev/null
+++ b/projects/web/src/main/java/cc/tweaked/web/js/fetch/Response.java
@@ -0,0 +1,38 @@
+// SPDX-FileCopyrightText: 2026 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.web.js.fetch;
+
+import org.teavm.jso.JSBody;
+import org.teavm.jso.JSObject;
+import org.teavm.jso.JSProperty;
+import org.teavm.jso.core.JSPromise;
+import org.teavm.jso.typedarrays.Uint8Array;
+
+/**
+ * The {@link Response} interface of the Fetch API represents the response to a request.
+ *
+ * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/Response">MDN Reference</a>
+ */
+public abstract class Response implements JSObject {
+    private Response() {
+    }
+
+    @JSBody(params = "url", script = "return fetch(url)")
+    public static native JSPromise<Response> fetch(String url);
+
+    @JSBody(params = { "url", "options" }, script = "return fetch(url, options)")
+    public static native JSPromise<Response> fetch(String url, RequestInit options);
+
+    @JSProperty
+    public native int getStatus();
+
+    @JSProperty
+    public native String getStatusText();
+
+    @JSProperty
+    public native Headers getHeaders();
+
+    public native JSPromise<Uint8Array> bytes();
+}
diff --git a/tools/parse-reports.py b/tools/parse-reports.py
index 44907d7b7..970803ffe 100755
--- a/tools/parse-reports.py
+++ b/tools/parse-reports.py
@@ -11,11 +11,11 @@ See https://github.com/actions/toolkit/blob/master/docs/problem-matchers.md and
 https://github.com/actions/toolkit/blob/master/docs/commands.md.
 """
 
+import dataclasses
 import os.path
 import pathlib
 import re
 import xml.etree.ElementTree as ET
-from typing import Optional, Tuple
 
 LUA_ERROR_LOCATION = re.compile(r"^\s+(/[\w./-]+):(\d+):", re.MULTILINE)
 JAVA_LUA_ERROR_LOCATION = re.compile(r"^java.lang.IllegalStateException: (/[\w./-]+):(\d+):")
@@ -42,10 +42,8 @@ PROJECT_LOCATIONS = [
     "projects/forge",
 ]
 
-TEST_REPORTS = []
 
-
-def find_file(path: str) -> Optional[str]:
+def find_file(path: str) -> str | None:
     while len(path) > 0 and path[0] == "/":
         path = path[1:]
 
@@ -58,7 +56,7 @@ def find_file(path: str) -> Optional[str]:
     return None
 
 
-def find_location(message: str) -> Optional[Tuple[str, str]]:
+def find_location(message: str) -> tuple[str, str] | None:
     location = LUA_ERROR_LOCATION.search(message)
     if location:
         file = find_file(location[1])
@@ -79,31 +77,60 @@ def find_location(message: str) -> Optional[Tuple[str, str]]:
     return None
 
 
+_OTR_CORE = "https://schemas.opentest4j.org/reporting/core/0.2.0"
+_OTR_EVENTS = "https://schemas.opentest4j.org/reporting/events/0.2.0"
+_OTR_JAVA = "https://schemas.opentest4j.org/reporting/java/0.2.0"
+
+
 def _parse_junit_file(path: pathlib.Path):
-    for testcase in ET.parse(path).findall(".//testcase"):
-        for result in testcase:
-            if result.tag == "skipped":
+    tests: dict[str, str] = {}
+    tree = ET.parse(path).getroot()
+    for event in tree:
+        if event.tag == f"{{{_OTR_CORE}}}infrastructure":
+            continue
+        elif event.tag == f"{{{_OTR_EVENTS}}}started":
+            test_id: str = event.get("id")
+            test_name: str = event.get("name")
+            if (parent_id := event.get("parentId")) is not None:
+                test_name = tests[parent_id] + " ⊳ " + test_name
+
+            tests[test_id] = test_name
+        elif event.tag == f"{{{_OTR_EVENTS}}}finished":
+            test_id: str = event.get("id")
+            test_name = tests[test_id]
+
+            result = event.find(f"./{{{_OTR_CORE}}}result")
+            if result is None:
                 continue
 
-            name = f'{testcase.attrib["classname"]}.{testcase.attrib["name"]}'
-            message = result.attrib.get("message")
-            full_message = result.text or message
+            if result.get("status") in ("SUCCESSFUL", "ABORTED"):
+                continue
+
+            reason = result.find(f"./{{{_OTR_CORE}}}reason")
+            throwable = result.find(f"./{{{_OTR_JAVA}}}throwable")
+
+            message = reason.text if reason is not None else ""
+            full_message = throwable.text if throwable is not None else ""
 
             location = find_location(full_message)
-            error = ERROR_MESSAGE.match(message)
-            if error:
-                error = error[1]
+            if (match := ERROR_MESSAGE.match(message)) is not None:
+                error = match.group(1)
             else:
                 error = message
+            error = SPACES.sub(' ', error)
 
             if location:
-                print(f'## {location[0]}:{location[1]}: {name} failed: {SPACES.sub(" ", error)}')
+                print(f"## {location[0]}:{location[1]}: {test_name} failed: {error}")
             else:
-                print(f"::error::{name} failed")
+                print(f"::error::{test_name} failed: {error}")
+
+            if len(full_message) > 0:
+                print("::group::Full error message")
+                print(full_message)
+                print("::endgroup::")
+        else:
+            print(f"Unknown tag: {event.tag}")
 
-            print("::group::Full error message")
-            print(full_message)
-            print("::endgroup::")
 
 
 def parse_junit() -> None:
@@ -114,7 +141,7 @@ def parse_junit() -> None:
     print("::add-matcher::.github/matchers/junit.json")
 
     for project in PROJECT_LOCATIONS:
-        for path in pathlib.Path(os.path.join(project, "build/test-results/test")).glob("TEST-*.xml"):
+        for path in pathlib.Path(os.path.join(project, "build/test-results")).glob("*/open-test-report.xml"):
             _parse_junit_file(path)
 
         for path in pathlib.Path(os.path.join(project, "build/test-results")).glob("run*.xml"):
@@ -130,7 +157,7 @@ def _parse_checkstyle(path: pathlib.Path):
 
             attrib = error.attrib
             print(
-                f'{attrib["severity"]} {filename}:{attrib["line"]}:{attrib.get("column", 1)}: {SPACES.sub(" ", attrib["message"])}'
+                f"{attrib['severity']} {filename}:{attrib['line']}:{attrib.get('column', 1)}: {SPACES.sub(' ', attrib['message'])}"
             )