Add support for libmultipart to wireless modems

This is a little nasty as we need to include ForgeGradle's repo too, but
should still help a bit!

.github/workflows/main-ci.yml

@@ -28,10 +28,13 @@ jobs:
         echo "org.gradle.daemon=false" >> ~/.gradle/gradle.properties
 
     - name: Build with Gradle
-      run: |
-        ./gradlew assemble || ./gradlew assemble
-        ./gradlew downloadAssets || ./gradlew downloadAssets
-        ./gradlew build
+      run: ./gradlew assemble || ./gradlew assemble
+
+    - name: Download assets for game tests
+      run: ./gradlew downloadAssets || ./gradlew downloadAssets
+
+    - name: Run tests and linters
+      run: ./gradlew build
 
     - name: Run client tests
       run: ./gradlew runGametestClient # Not checkClient, as no point running rendering tests.

.github/workflows/make-doc.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
     - mc-1.19.x
+    - mc-1.20.x
 
 jobs:
   make_doc:

buildSrc/src/main/kotlin/cc-tweaked.forge.gradle.kts

@@ -10,8 +10,9 @@ import cc.tweaked.gradle.IdeaRunConfigurations
 import cc.tweaked.gradle.MinecraftConfigurations
 
 plugins {
-    id("cc-tweaked.java-convention")
     id("net.minecraftforge.gradle")
+    // We must apply java-convention after Forge, as we need the fg extension to be present.
+    id("cc-tweaked.java-convention")
     id("org.parchmentmc.librarian.forgegradle")
 }
 

buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts

@@ -37,20 +37,35 @@ java {
 
 repositories {
     mavenCentral()
-    maven("https://squiddev.cc/maven") {
+
+    val mainMaven = maven("https://squiddev.cc/maven") {
         name = "SquidDev"
         content {
+            // Until https://github.com/SpongePowered/Mixin/pull/593 is merged
+            includeModule("org.spongepowered", "mixin")
+        }
+    }
+
+    exclusiveContent {
+        forRepositories(mainMaven)
+
+        // Include the ForgeGradle repository if present. This requires that ForgeGradle is already present, which we
+        // enforce in our Forge overlay.
+        val fg =
+            project.extensions.findByType(net.minecraftforge.gradle.userdev.DependencyManagementExtension::class.java)
+        if (fg != null) forRepositories(fg.repository)
+
+        filter {
             includeGroup("org.squiddev")
             includeGroup("cc.tweaked")
             // Things we mirror
+            includeGroup("alexiil.mc.lib")
             includeGroup("dev.architectury")
             includeGroup("maven.modrinth")
             includeGroup("me.shedaniel")
             includeGroup("me.shedaniel.cloth")
             includeGroup("mezz.jei")
             includeModule("com.terraformersmc", "modmenu")
-            // Until https://github.com/SpongePowered/Mixin/pull/593 is merged
-            includeModule("org.spongepowered", "mixin")
         }
     }
 }
@@ -104,6 +119,7 @@ tasks.withType(JavaCompile::class.java).configureEach {
 
 tasks.processResources {
     exclude("**/*.license")
+    exclude(".cache")
 }
 
 tasks.withType(AbstractArchiveTask::class.java).configureEach {

buildSrc/src/main/kotlin/cc/tweaked/gradle/Extensions.kt

@@ -49,6 +49,7 @@ fun JavaExec.copyToFull(spec: JavaExec) {
  * Copy additional [BaseExecSpec] options which aren't handled by [ProcessForkOptions.copyTo].
  */
 fun BaseExecSpec.copyToExec(spec: BaseExecSpec) {
+    spec.workingDir = workingDir
     spec.isIgnoreExitValue = isIgnoreExitValue
     if (standardInput != null) spec.standardInput = standardInput
     if (standardOutput != null) spec.standardOutput = standardOutput

buildSrc/src/main/kotlin/cc/tweaked/gradle/ForgeExtensions.kt

@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.gradle
+
+import net.minecraftforge.gradle.common.util.RunConfig
+import net.minecraftforge.gradle.common.util.runs.setRunConfigInternal
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.api.tasks.JavaExec
+import org.gradle.jvm.toolchain.JavaToolchainService
+import java.nio.file.Files
+
+/**
+ * Set [JavaExec] task to run a given [RunConfig].
+ */
+fun JavaExec.setRunConfig(config: RunConfig) {
+    dependsOn("prepareRuns")
+    setRunConfigInternal(project, this, config)
+    doFirst("Create working directory") { Files.createDirectories(workingDir.toPath()) }
+
+    javaLauncher.set(
+        project.extensions.getByType(JavaToolchainService::class.java)
+            .launcherFor(project.extensions.getByType(JavaPluginExtension::class.java).toolchain),
+    )
+}

buildSrc/src/main/kotlin/cc/tweaked/gradle/Illuaminate.kt

@@ -60,7 +60,7 @@ class IlluaminatePlugin : Plugin<Project> {
 
     /** Define a dependency for illuaminate from a version number and the current operating system. */
     private fun illuaminateArtifact(project: Project, version: String): Dependency {
-        val osName = System.getProperty("os.name").toLowerCase()
+        val osName = System.getProperty("os.name").lowercase()
         val (os, suffix) = when {
             osName.contains("windows") -> Pair("windows", ".exe")
             osName.contains("mac os") || osName.contains("darwin") -> Pair("macos", "")
@@ -68,7 +68,7 @@ class IlluaminatePlugin : Plugin<Project> {
             else -> error("Unsupported OS $osName for illuaminate")
         }
 
-        val osArch = System.getProperty("os.arch").toLowerCase()
+        val osArch = System.getProperty("os.arch").lowercase()
         val arch = when {
             // On macOS the x86_64 binary will work for both ARM and Intel Macs through Rosetta.
             os == "macos" -> "x86_64"

buildSrc/src/main/kotlin/cc/tweaked/gradle/MinecraftExec.kt

@@ -32,11 +32,14 @@ abstract class ClientJavaExec : JavaExec() {
         usesService(clientRunner)
     }
 
+    @get:Input
+    val renderdoc get() = project.hasProperty("renderdoc")
+
     /**
      * When [false], tests will not be run automatically, allowing the user to debug rendering.
      */
     @get:Input
-    val clientDebug get() = project.hasProperty("clientDebug")
+    val clientDebug get() = renderdoc || project.hasProperty("clientDebug")
 
     /**
      * When [false], tests will not run under a framebuffer.
@@ -63,6 +66,7 @@ abstract class ClientJavaExec : JavaExec() {
         task.copyToFull(this)
 
         if (!clientDebug) systemProperty("cctest.client", "")
+        if (renderdoc) environment("LD_PRELOAD", "/usr/lib/librenderdoc.so")
         systemProperty("cctest.gametest-report", testResults.get().asFile.absoluteFile)
         workingDir(project.buildDir.resolve("gametest").resolve(name))
     }

buildSrc/src/main/kotlin/net/minecraftforge/gradle/common/util/runs/RunConfigSetup.kt

@@ -0,0 +1,70 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package net.minecraftforge.gradle.common.util.runs
+
+import net.minecraftforge.gradle.common.util.RunConfig
+import org.gradle.api.Project
+import org.gradle.process.CommandLineArgumentProvider
+import org.gradle.process.JavaExecSpec
+import java.io.File
+import java.util.function.Supplier
+import java.util.stream.Collectors
+import java.util.stream.Stream
+
+/**
+ * Set up a [JavaExecSpec] to execute a [RunConfig].
+ *
+ * [MinecraftRunTask] sets up all its properties when the task is executed, rather than when configured. As such, it's
+ * not possible to use [cc.tweaked.gradle.copyToFull] like we do for Fabric. Instead, we set up the task manually.
+ *
+ * Unfortunately most of the functionality we need is package-private, and so we have to put our code into the package.
+ */
+internal fun setRunConfigInternal(project: Project, spec: JavaExecSpec, config: RunConfig) {
+    spec.workingDir = File(config.workingDirectory)
+
+    spec.mainClass.set(config.main)
+    for (source in config.allSources) spec.classpath(source.runtimeClasspath)
+
+    val originalTask = project.tasks.named(config.taskName, MinecraftRunTask::class.java)
+
+    // Add argument and JVM argument via providers, to be as lazy as possible with fetching artifacts.
+    fun lazyTokens(): MutableMap<String, Supplier<String>> {
+        return RunConfigGenerator.configureTokensLazy(
+            project, config, RunConfigGenerator.mapModClassesToGradle(project, config),
+            originalTask.get().minecraftArtifacts.files,
+            originalTask.get().runtimeClasspathArtifacts.files,
+        )
+    }
+    spec.argumentProviders.add(
+        CommandLineArgumentProvider {
+            RunConfigGenerator.getArgsStream(config, lazyTokens(), false).toList()
+        },
+    )
+    spec.jvmArgumentProviders.add(
+        CommandLineArgumentProvider {
+            val lazyTokens = lazyTokens()
+            (if (config.isClient) config.jvmArgs + originalTask.get().additionalClientArgs.get() else config.jvmArgs).map { config.replace(lazyTokens, it) } +
+                config.properties.map { (k, v) -> "-D${k}=${config.replace(lazyTokens, v)}" }
+        },
+    )
+
+    // We can't configure environment variables lazily, so we do these now with a more minimal lazyTokens set.
+    val lazyTokens = mutableMapOf<String, Supplier<String>>()
+    for ((k, v) in config.tokens) lazyTokens[k] = Supplier<String> { v }
+    for ((k, v) in config.lazyTokens) lazyTokens[k] = v
+    lazyTokens.compute(
+        "source_roots",
+        { _, sourceRoots ->
+            Supplier<String> {
+                val modClasses = RunConfigGenerator.mapModClassesToGradle(project, config)
+                (when (sourceRoots) {
+                    null -> modClasses
+                    else -> Stream.concat<String>(sourceRoots.get().split(File.pathSeparator).stream(), modClasses)
+                }).distinct().collect(Collectors.joining(File.pathSeparator))
+            }
+        },
+    )
+    for ((key, value) in config.environment) spec.environment(key, config.replace(lazyTokens, value))
+}

gradle/libs.versions.toml

@@ -35,6 +35,7 @@ slf4j = "1.7.36"
 # Minecraft mods
 iris = "1.5.2+1.19.4"
 jei = "13.1.0.11"
+libmultipart = "0.10.0"
 modmenu = "6.1.0-rc.1"
 oculus = "1.2.5"
 rei = "10.0.578"
@@ -53,11 +54,11 @@ checkstyle = "10.3.4"
 curseForgeGradle = "1.0.14"
 errorProne-core = "2.18.0"
 errorProne-plugin = "3.0.1"
-fabric-loom = "1.1.10"
-forgeGradle = "5.1.+"
+fabric-loom = "1.2.7"
+forgeGradle = "6.0.6"
 githubRelease = "2.2.12"
 ideaExt = "1.1.6"
-illuaminate = "0.1.0-24-gdb28902"
+illuaminate = "0.1.0-28-ga7efd71"
 librarian = "1.+"
 minotaur = "2.+"
 mixinGradle = "0.7.+"
@@ -96,6 +97,7 @@ iris = { module = "maven.modrinth:iris", version.ref = "iris" }
 jei-api = { module = "mezz.jei:jei-1.19.4-common-api", version.ref = "jei" }
 jei-fabric = { module = "mezz.jei:jei-1.19.4-fabric", version.ref = "jei" }
 jei-forge = { module = "mezz.jei:jei-1.19.4-forge", version.ref = "jei" }
+libmultipart = { module = "alexiil.mc.lib:libmultipart-all", version.ref = "libmultipart" }
 mixin = { module = "org.spongepowered:mixin", version.ref = "mixin" }
 modmenu = { module = "com.terraformersmc:modmenu", version.ref = "modmenu" }
 oculus = { module = "maven.modrinth:oculus", version.ref = "oculus" }
@@ -152,7 +154,7 @@ externalMods-common = ["jei-api", "nightConfig-core", "nightConfig-toml"]
 externalMods-forge-compile = ["oculus", "jei-api"]
 externalMods-forge-runtime = ["jei-forge"]
 externalMods-fabric = ["nightConfig-core", "nightConfig-toml"]
-externalMods-fabric-compile = ["iris", "jei-api", "rei-api", "rei-builtin"]
+externalMods-fabric-compile = ["iris", "jei-api", "rei-api", "rei-builtin", "libmultipart"]
 externalMods-fabric-runtime = ["jei-fabric", "modmenu"]
 
 # Testing

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.1.1-bin.zip
+networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +80,10 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -143,12 +140,16 @@ fi
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,6 +194,10 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
 # Collect all arguments for the java command;
 #   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
 #     shell script including quotes and variable substitutions, so put them in

gradlew.bat

@@ -26,6 +26,7 @@ if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
 if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 

projects/common-api/src/client/java/dan200/computercraft/api/client/turtle/TurtleUpgradeModeller.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.api.turtle.TurtleUpgradeSerialiser;
 import net.minecraft.client.resources.model.ModelResourceLocation;
+import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 
 import javax.annotation.Nullable;
@@ -28,12 +29,27 @@ public interface TurtleUpgradeModeller<T extends ITurtleUpgrade> {
      * When the current turtle is {@literal null}, this function should be constant for a given upgrade and side.
      *
      * @param upgrade The upgrade that you're getting the model for.
-     * @param turtle  Access to the turtle that the upgrade resides on. This will be null when getting item models!
+     * @param turtle  Access to the turtle that the upgrade resides on. This will be null when getting item models, unless
+     *                {@link #getModel(ITurtleUpgrade, CompoundTag, TurtleSide)} is overriden.
      * @param side    Which side of the turtle (left or right) the upgrade resides on.
      * @return The model that you wish to be used to render your upgrade.
      */
     TransformedModel getModel(T upgrade, @Nullable ITurtleAccess turtle, TurtleSide side);
 
+    /**
+     * Obtain the model to be used when rendering a turtle peripheral.
+     * <p>
+     * This is used when rendering the turtle's item model, and so no {@link ITurtleAccess} is available.
+     *
+     * @param upgrade The upgrade that you're getting the model for.
+     * @param data    Upgrade data instance for current turtle side.
+     * @param side    Which side of the turtle (left or right) the upgrade resides on.
+     * @return The model that you wish to be used to render your upgrade.
+     */
+    default TransformedModel getModel(T upgrade, CompoundTag data, TurtleSide side) {
+        return getModel(upgrade, (ITurtleAccess) null, side);
+    }
+
     /**
      * A basic {@link TurtleUpgradeModeller} which renders using the upgrade's {@linkplain ITurtleUpgrade#getCraftingItem()
      * crafting item}.

projects/common-api/src/main/java/dan200/computercraft/api/pocket/IPocketAccess.java

@@ -5,9 +5,11 @@
 package dan200.computercraft.api.pocket;
 
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.api.upgrades.UpgradeBase;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.Entity;
+import net.minecraft.world.item.ItemStack;
 
 import javax.annotation.Nullable;
 import java.util.Map;
@@ -69,6 +71,8 @@ public interface IPocketAccess {
      *
      * @return The upgrade's NBT.
      * @see #updateUpgradeNBTData()
+     * @see UpgradeBase#getUpgradeItem(CompoundTag)
+     * @see UpgradeBase#getUpgradeData(ItemStack)
      */
     CompoundTag getUpgradeNBTData();
 
@@ -80,7 +84,10 @@ public interface IPocketAccess {
     void updateUpgradeNBTData();
 
     /**
-     * Remove the current peripheral and create a new one. You may wish to do this if the methods available change.
+     * Remove the current peripheral and create a new one.
+     * <p>
+     * You may wish to do this if the methods available change, for instance when the {@linkplain #getEntity() owning
+     * entity} changes.
      */
     void invalidatePeripheral();
 
@@ -88,6 +95,8 @@ public interface IPocketAccess {
      * Get a list of all upgrades for the pocket computer.
      *
      * @return A collection of all upgrade names.
+     * @deprecated This is a relic of a previous API, which no longer makes sense with newer versions of ComputerCraft.
      */
+    @Deprecated(forRemoval = true)
     Map<ResourceLocation, IPeripheral> getUpgrades();
 }

projects/common-api/src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -8,10 +8,13 @@ import com.mojang.authlib.GameProfile;
 import dan200.computercraft.api.lua.ILuaCallback;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.api.upgrades.UpgradeBase;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.world.Container;
+import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.phys.Vec3;
 import org.jetbrains.annotations.ApiStatus;
@@ -245,23 +248,51 @@ public interface ITurtleAccess {
     void playAnimation(TurtleAnimation animation);
 
     /**
-     * Returns the turtle on the specified side of the turtle, if there is one.
+     * Returns the upgrade on the specified side of the turtle, if there is one.
      *
      * @param side The side to get the upgrade from.
      * @return The upgrade on the specified side of the turtle, if there is one.
-     * @see #setUpgrade(TurtleSide, ITurtleUpgrade)
+     * @see #getUpgradeWithData(TurtleSide)
+     * @see #setUpgradeWithData(TurtleSide, UpgradeData)
      */
     @Nullable
     ITurtleUpgrade getUpgrade(TurtleSide side);
 
+    /**
+     * Returns the upgrade on the specified side of the turtle, along with its {@linkplain #getUpgradeNBTData(TurtleSide)
+     * update data}.
+     *
+     * @param side The side to get the upgrade from.
+     * @return The upgrade on the specified side of the turtle, along with its upgrade data, if there is one.
+     * @see #getUpgradeWithData(TurtleSide)
+     * @see #setUpgradeWithData(TurtleSide, UpgradeData)
+     */
+    default @Nullable UpgradeData<ITurtleUpgrade> getUpgradeWithData(TurtleSide side) {
+        var upgrade = getUpgrade(side);
+        return upgrade == null ? null : UpgradeData.of(upgrade, getUpgradeNBTData(side));
+    }
+
     /**
      * Set the upgrade for a given side, resetting peripherals and clearing upgrade specific data.
      *
      * @param side    The side to set the upgrade on.
      * @param upgrade The upgrade to set, may be {@code null} to clear.
      * @see #getUpgrade(TurtleSide)
+     * @deprecated Use {@link #setUpgradeWithData(TurtleSide, UpgradeData)}
      */
-    void setUpgrade(TurtleSide side, @Nullable ITurtleUpgrade upgrade);
+    @Deprecated
+    default void setUpgrade(TurtleSide side, @Nullable ITurtleUpgrade upgrade) {
+        setUpgradeWithData(side, upgrade == null ? null : UpgradeData.ofDefault(upgrade));
+    }
+
+    /**
+     * Set the upgrade for a given side and its upgrade data.
+     *
+     * @param side    The side to set the upgrade on.
+     * @param upgrade The upgrade to set, may be {@code null} to clear.
+     * @see #getUpgradeWithData(TurtleSide)
+     */
+    void setUpgradeWithData(TurtleSide side, @Nullable UpgradeData<ITurtleUpgrade> upgrade);
 
     /**
      * Returns the peripheral created by the upgrade on the specified side of the turtle, if there is one.
@@ -281,6 +312,8 @@ public interface ITurtleAccess {
      * @param side The side to get the upgrade data for.
      * @return The upgrade-specific data.
      * @see #updateUpgradeNBTData(TurtleSide)
+     * @see UpgradeBase#getUpgradeItem(CompoundTag)
+     * @see UpgradeBase#getUpgradeData(ItemStack)
      */
     CompoundTag getUpgradeNBTData(TurtleSide side);
 

projects/common-api/src/main/java/dan200/computercraft/api/turtle/ITurtleUpgrade.java

@@ -7,6 +7,7 @@ package dan200.computercraft.api.turtle;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.upgrades.UpgradeBase;
 import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
 
 import javax.annotation.Nullable;
 
@@ -79,4 +80,17 @@ public interface ITurtleUpgrade extends UpgradeBase {
      */
     default void update(ITurtleAccess turtle, TurtleSide side) {
     }
+
+    /**
+     * Get upgrade data that should be persisted when the turtle was broken.
+     * <p>
+     * This method should be overridden when you don't need to store all upgrade data by default. For instance, if you
+     * store peripheral state in the upgrade data, which should be lost when the turtle is broken.
+     *
+     * @param upgradeData Data that currently stored for this upgrade
+     * @return Filtered version of this data.
+     */
+    default CompoundTag getPersistedData(CompoundTag upgradeData) {
+        return upgradeData;
+    }
 }

projects/common-api/src/main/java/dan200/computercraft/api/upgrades/UpgradeBase.java

@@ -4,10 +4,14 @@
 
 package dan200.computercraft.api.upgrades;
 
+import dan200.computercraft.api.pocket.IPocketAccess;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.turtle.ITurtleAccess;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.impl.PlatformHelper;
 import net.minecraft.Util;
+import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.item.ItemStack;
 
@@ -50,6 +54,42 @@ public interface UpgradeBase {
      */
     ItemStack getCraftingItem();
 
+    /**
+     * Returns the item stack representing a currently equipped turtle upgrade.
+     * <p>
+     * While upgrades can store upgrade data ({@link ITurtleAccess#getUpgradeNBTData(TurtleSide)} and
+     * {@link IPocketAccess#getUpgradeNBTData()}}, by default this data is discarded when an upgrade is unequipped,
+     * and the original item stack is returned.
+     * <p>
+     * By overriding this method, you can create a new {@link ItemStack} which contains enough data to
+     * {@linkplain #getUpgradeData(ItemStack) re-create the upgrade data} if the item is re-equipped.
+     * <p>
+     * When overriding this, you should override {@link #getUpgradeData(ItemStack)} and {@link #isItemSuitable(ItemStack)}
+     * at the same time,
+     *
+     * @param upgradeData The current upgrade data. This should <strong>NOT</strong> be mutated.
+     * @return The item stack returned when unequipping.
+     */
+    default ItemStack getUpgradeItem(CompoundTag upgradeData) {
+        return getCraftingItem();
+    }
+
+    /**
+     * Extract upgrade data from an {@link ItemStack}.
+     * <p>
+     * This upgrade data will be available with {@link ITurtleAccess#getUpgradeNBTData(TurtleSide)} or
+     * {@link IPocketAccess#getUpgradeNBTData()}.
+     * <p>
+     * This should be an inverse to {@link #getUpgradeItem(CompoundTag)}.
+     *
+     * @param stack The stack that was equipped by the turtle or pocket computer. This will have the same item as
+     *              {@link #getCraftingItem()}.
+     * @return The upgrade data that should be set on the turtle or pocket computer.
+     */
+    default CompoundTag getUpgradeData(ItemStack stack) {
+        return new CompoundTag();
+    }
+
     /**
      * Determine if an item is suitable for being used for this upgrade.
      * <p>

projects/common-api/src/main/java/dan200/computercraft/api/upgrades/UpgradeData.java

@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.api.upgrades;
+
+import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.Contract;
+
+import javax.annotation.Nullable;
+
+/**
+ * An upgrade (i.e. a {@link ITurtleUpgrade}) and its current upgrade data.
+ * <p>
+ * <strong>IMPORTANT:</strong> The {@link #data()} in an upgrade data is often a reference to the original upgrade data.
+ * Be careful to take a {@linkplain #copy() defensive copy} if you plan to use the data in this upgrade.
+ *
+ * @param upgrade The current upgrade.
+ * @param data    The upgrade's data.
+ * @param <T>     The type of upgrade, either {@link ITurtleUpgrade} or {@link IPocketUpgrade}.
+ */
+public record UpgradeData<T extends UpgradeBase>(T upgrade, CompoundTag data) {
+    /**
+     * A utility method to construct a new {@link UpgradeData} instance.
+     *
+     * @param upgrade An upgrade.
+     * @param data    The upgrade's data.
+     * @param <T>     The type of upgrade.
+     * @return The new {@link UpgradeData} instance.
+     */
+    public static <T extends UpgradeBase> UpgradeData<T> of(T upgrade, CompoundTag data) {
+        return new UpgradeData<>(upgrade, data);
+    }
+
+    /**
+     * Create an {@link UpgradeData} containing the default {@linkplain #data() data} for an upgrade.
+     *
+     * @param upgrade The upgrade instance.
+     * @param <T>     The type of upgrade.
+     * @return The default upgrade data.
+     */
+    public static <T extends UpgradeBase> UpgradeData<T> ofDefault(T upgrade) {
+        return of(upgrade, upgrade.getUpgradeData(upgrade.getCraftingItem()));
+    }
+
+    /**
+     * Take a copy of a (possibly {@code null}) {@link UpgradeData} instance.
+     *
+     * @param upgrade The copied upgrade data.
+     * @param <T>     The type of upgrade.
+     * @return The newly created upgrade data.
+     */
+    @Contract("!null -> !null; null -> null")
+    public static <T extends UpgradeBase> @Nullable UpgradeData<T> copyOf(@Nullable UpgradeData<T> upgrade) {
+        return upgrade == null ? null : upgrade.copy();
+    }
+
+    /**
+     * Get the {@linkplain UpgradeBase#getUpgradeItem(CompoundTag) upgrade item} for this upgrade.
+     * <p>
+     * This returns a defensive copy of the item, to prevent accidental mutation of the upgrade data or original
+     * {@linkplain UpgradeBase#getCraftingItem() upgrade stack}.
+     *
+     * @return This upgrade's item.
+     */
+    public ItemStack getUpgradeItem() {
+        return upgrade.getUpgradeItem(data).copy();
+    }
+
+    /**
+     * Take a copy of this {@link UpgradeData}. This returns a new instance with the same upgrade and a fresh copy of
+     * the upgrade data.
+     *
+     * @return A copy of the current instance.
+     */
+    public UpgradeData<T> copy() {
+        return new UpgradeData<>(upgrade(), data().copy());
+    }
+}

projects/common-api/src/main/java/dan200/computercraft/api/upgrades/UpgradeDataProvider.java

@@ -24,6 +24,7 @@ import org.apache.logging.log4j.Logger;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -104,7 +105,7 @@ public abstract class UpgradeDataProvider<T extends UpgradeBase, R extends Upgra
     protected abstract void addUpgrades(Consumer<Upgrade<R>> addUpgrade);
 
     @Override
-    public final CompletableFuture<?> run(CachedOutput cache) {
+    public CompletableFuture<?> run(CachedOutput cache) {
         var base = output.getOutputFolder().resolve("data");
 
         Set<ResourceLocation> seen = new HashSet<>();
@@ -127,7 +128,7 @@ public abstract class UpgradeDataProvider<T extends UpgradeBase, R extends Upgra
             }
         });
 
-        this.upgrades = upgrades;
+        this.upgrades = Collections.unmodifiableList(upgrades);
         return Util.sequenceFailFast(futures);
     }
 

projects/common/build.gradle.kts

@@ -7,6 +7,7 @@ import cc.tweaked.gradle.clientClasses
 import cc.tweaked.gradle.commonClasses
 
 plugins {
+    id("cc-tweaked.publishing")
     id("cc-tweaked.vanilla")
     id("cc-tweaked.gametest")
 }

projects/common/src/client/java/dan200/computercraft/client/gui/TurtleScreen.java

@@ -26,9 +26,11 @@ public class TurtleScreen extends AbstractComputerScreen<TurtleMenu> {
     private static final ResourceLocation BACKGROUND_NORMAL = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/turtle_normal.png");
     private static final ResourceLocation BACKGROUND_ADVANCED = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/turtle_advanced.png");
 
-    private static final int TEX_WIDTH = 254;
+    private static final int TEX_WIDTH = 278;
     private static final int TEX_HEIGHT = 217;
 
+    private static final int FULL_TEX_SIZE = 512;
+
     public TurtleScreen(TurtleMenu container, Inventory player, Component title) {
         super(container, player, title, BORDER);
 
@@ -45,16 +47,16 @@ public class TurtleScreen extends AbstractComputerScreen<TurtleMenu> {
     protected void renderBg(PoseStack transform, float partialTicks, int mouseX, int mouseY) {
         var advanced = family == ComputerFamily.ADVANCED;
         RenderSystem.setShaderTexture(0, advanced ? BACKGROUND_ADVANCED : BACKGROUND_NORMAL);
-        blit(transform, leftPos + AbstractComputerMenu.SIDEBAR_WIDTH, topPos, 0, 0, TEX_WIDTH, TEX_HEIGHT);
+        blit(transform, leftPos + AbstractComputerMenu.SIDEBAR_WIDTH, topPos, 0, 0, 0, TEX_WIDTH, TEX_HEIGHT, FULL_TEX_SIZE, FULL_TEX_SIZE);
 
+        // Render selected slot
         var slot = getMenu().getSelectedSlot();
         if (slot >= 0) {
-            RenderSystem.setShaderColor(1.0F, 1.0F, 1.0F, 1.0F);
             var slotX = slot % 4;
             var slotY = slot / 4;
             blit(transform,
-                leftPos + TURTLE_START_X - 2 + slotX * 18, topPos + PLAYER_START_Y - 2 + slotY * 18,
-                0, 217, 24, 24
+                leftPos + TURTLE_START_X - 2 + slotX * 18, topPos + PLAYER_START_Y - 2 + slotY * 18, 0,
+                0, 217, 24, 24, FULL_TEX_SIZE, FULL_TEX_SIZE
             );
         }
 

projects/common/src/client/java/dan200/computercraft/client/model/turtle/ModelTransformer.java

@@ -0,0 +1,98 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.client.model.turtle;
+
+import com.mojang.blaze3d.vertex.DefaultVertexFormat;
+import com.mojang.blaze3d.vertex.VertexFormat;
+import com.mojang.blaze3d.vertex.VertexFormatElement;
+import com.mojang.math.Transformation;
+import net.minecraft.client.renderer.block.model.BakedQuad;
+import net.minecraft.client.resources.model.BakedModel;
+import net.minecraft.core.Direction;
+import org.joml.Matrix4f;
+import org.joml.Vector4f;
+
+import javax.annotation.Nullable;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Applies a {@link Transformation} (or rather a {@link Matrix4f}) to a list of {@link BakedQuad}s.
+ * <p>
+ * This does a little bit of magic compared with other system (i.e. Forge's {@code QuadTransformers}), as it needs to
+ * handle flipping models upside down.
+ * <p>
+ * This is typically used with a {@link BakedModel} subclass - see the loader-specific projects.
+ */
+public final class ModelTransformer {
+    public static final int[] ORDER = new int[]{ 3, 2, 1, 0 };
+    public static final int STRIDE = DefaultVertexFormat.BLOCK.getIntegerSize();
+    private static final int POS_OFFSET = findOffset(DefaultVertexFormat.BLOCK, DefaultVertexFormat.ELEMENT_POSITION);
+
+    private final Matrix4f transformation;
+    private final boolean invert;
+    private @Nullable TransformedQuads cache;
+
+    public ModelTransformer(Transformation transformation) {
+        this.transformation = transformation.getMatrix();
+        invert = transformation.getMatrix().determinant() < 0;
+    }
+
+    public List<BakedQuad> transform(List<BakedQuad> quads) {
+        if (quads.isEmpty()) return List.of();
+
+        // We do some basic caching here to avoid recomputing every frame. Most turtle models don't have culled faces,
+        // so it's not worth being smarter here.
+        var cache = this.cache;
+        if (cache != null && quads.equals(cache.original())) return cache.transformed();
+
+        List<BakedQuad> transformed = new ArrayList<>(quads.size());
+        for (var quad : quads) transformed.add(transformQuad(quad));
+        this.cache = new TransformedQuads(quads, transformed);
+        return transformed;
+    }
+
+    private BakedQuad transformQuad(BakedQuad quad) {
+        var inputData = quad.getVertices();
+        var outputData = new int[inputData.length];
+        for (var i = 0; i < 4; i++) {
+            var inStart = STRIDE * i;
+            // Reverse the order of the quads if we're inverting
+            var outStart = STRIDE * (invert ? ORDER[i] : i);
+            System.arraycopy(inputData, inStart, outputData, outStart, STRIDE);
+
+            // Apply the matrix to our position
+            var inPosStart = inStart + POS_OFFSET;
+            var outPosStart = outStart + POS_OFFSET;
+
+            var x = Float.intBitsToFloat(inputData[inPosStart]);
+            var y = Float.intBitsToFloat(inputData[inPosStart + 1]);
+            var z = Float.intBitsToFloat(inputData[inPosStart + 2]);
+
+            // Transform the position
+            var pos = new Vector4f(x, y, z, 1);
+            transformation.transformProject(pos);
+
+            outputData[outPosStart] = Float.floatToRawIntBits(pos.x());
+            outputData[outPosStart + 1] = Float.floatToRawIntBits(pos.y());
+            outputData[outPosStart + 2] = Float.floatToRawIntBits(pos.z());
+        }
+
+        var direction = Direction.rotate(transformation, quad.getDirection());
+        return new BakedQuad(outputData, quad.getTintIndex(), direction, quad.getSprite(), quad.isShade());
+    }
+
+    private record TransformedQuads(List<BakedQuad> original, List<BakedQuad> transformed) {
+    }
+
+    private static int findOffset(VertexFormat format, VertexFormatElement element) {
+        var offset = 0;
+        for (var other : format.getElements()) {
+            if (other == element) return offset / Integer.BYTES;
+            offset += element.getByteSize();
+        }
+        throw new IllegalArgumentException("Cannot find " + element + " in " + format);
+    }
+}

projects/common/src/client/java/dan200/computercraft/client/model/turtle/TurtleModelParts.java

@@ -4,11 +4,13 @@
 
 package dan200.computercraft.client.model.turtle;
 
+import com.google.common.cache.CacheBuilder;
 import com.mojang.blaze3d.vertex.PoseStack;
 import com.mojang.math.Transformation;
 import dan200.computercraft.api.client.TransformedModel;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.client.platform.ClientPlatformHelper;
 import dan200.computercraft.client.render.TurtleBlockEntityRenderer;
 import dan200.computercraft.client.turtle.TurtleUpgradeModellers;
@@ -21,15 +23,17 @@ import net.minecraft.world.item.ItemStack;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 
 /**
  * Combines several individual models together to form a turtle.
+ *
+ * @param <T> The type of the resulting "baked model".
  */
-public final class TurtleModelParts {
+public final class TurtleModelParts<T> {
     private static final Transformation identity, flip;
 
     static {
@@ -42,33 +46,67 @@ public final class TurtleModelParts {
         flip = new Transformation(stack.last().pose());
     }
 
-    public record Combination(
+    private record Combination(
         boolean colour,
-        @Nullable ITurtleUpgrade leftUpgrade,
-        @Nullable ITurtleUpgrade rightUpgrade,
+        @Nullable UpgradeData<ITurtleUpgrade> leftUpgrade,
+        @Nullable UpgradeData<ITurtleUpgrade> rightUpgrade,
         @Nullable ResourceLocation overlay,
         boolean christmas,
         boolean flip
     ) {
+        Combination copy() {
+            if (leftUpgrade == null && rightUpgrade == null) return this;
+            return new Combination(
+                colour, UpgradeData.copyOf(leftUpgrade), UpgradeData.copyOf(rightUpgrade),
+                overlay, christmas, flip
+            );
+        }
     }
 
     private final BakedModel familyModel;
     private final BakedModel colourModel;
     private final Function<TransformedModel, BakedModel> transformer;
+    private final Function<Combination, T> buildModel;
 
     /**
      * A cache of {@link TransformedModel} to the transformed {@link BakedModel}. This helps us pool the transformed
      * instances, reducing memory usage and hopefully ensuring their caches are hit more often!
      */
-    private final Map<TransformedModel, BakedModel> transformCache = new HashMap<>();
+    private final Map<TransformedModel, BakedModel> transformCache = CacheBuilder.newBuilder()
+        .concurrencyLevel(1)
+        .expireAfterAccess(30, TimeUnit.SECONDS)
+        .<TransformedModel, BakedModel>build()
+        .asMap();
 
-    public TurtleModelParts(BakedModel familyModel, BakedModel colourModel, ModelTransformer transformer) {
+    /**
+     * A cache of {@link Combination}s to the combined model.
+     */
+    private final Map<Combination, T> modelCache = CacheBuilder.newBuilder()
+        .concurrencyLevel(1)
+        .expireAfterAccess(30, TimeUnit.SECONDS)
+        .<Combination, T>build()
+        .asMap();
+
+    public TurtleModelParts(BakedModel familyModel, BakedModel colourModel, ModelTransformer transformer, Function<List<BakedModel>, T> combineModel) {
         this.familyModel = familyModel;
         this.colourModel = colourModel;
         this.transformer = x -> transformer.transform(x.getModel(), x.getMatrix());
+        buildModel = x -> combineModel.apply(buildModel(x));
     }
 
-    public Combination getCombination(ItemStack stack) {
+    public T getModel(ItemStack stack) {
+        var combination = getCombination(stack);
+        var existing = modelCache.get(combination);
+        if (existing != null) return existing;
+
+        // Take a defensive copy of the upgrade data, and add it to the cache.
+        var newCombination = combination.copy();
+        var newModel = buildModel.apply(newCombination);
+        modelCache.put(newCombination, newModel);
+        return newModel;
+    }
+
+    private Combination getCombination(ItemStack stack) {
         var christmas = Holiday.getCurrent() == Holiday.CHRISTMAS;
 
         if (!(stack.getItem() instanceof TurtleItem turtle)) {
@@ -76,8 +114,8 @@ public final class TurtleModelParts {
         }
 
         var colour = turtle.getColour(stack);
-        var leftUpgrade = turtle.getUpgrade(stack, TurtleSide.LEFT);
-        var rightUpgrade = turtle.getUpgrade(stack, TurtleSide.RIGHT);
+        var leftUpgrade = turtle.getUpgradeWithData(stack, TurtleSide.LEFT);
+        var rightUpgrade = turtle.getUpgradeWithData(stack, TurtleSide.RIGHT);
         var overlay = turtle.getOverlay(stack);
         var label = turtle.getLabel(stack);
         var flip = label != null && (label.equals("Dinnerbone") || label.equals("Grumm"));
@@ -85,7 +123,7 @@ public final class TurtleModelParts {
         return new Combination(colour != -1, leftUpgrade, rightUpgrade, overlay, christmas, flip);
     }
 
-    public List<BakedModel> buildModel(Combination combo) {
+    private List<BakedModel> buildModel(Combination combo) {
         var mc = Minecraft.getInstance();
         var modelManager = mc.getItemRenderer().getItemModelShaper().getModelManager();
 
@@ -97,19 +135,20 @@ public final class TurtleModelParts {
         if (overlayModelLocation != null) {
             parts.add(transform(ClientPlatformHelper.get().getModel(modelManager, overlayModelLocation), transformation));
         }
-        if (combo.leftUpgrade() != null) {
-            var model = TurtleUpgradeModellers.getModel(combo.leftUpgrade(), null, TurtleSide.LEFT);
-            parts.add(transform(model.getModel(), transformation.compose(model.getMatrix())));
-        }
-        if (combo.rightUpgrade() != null) {
-            var model = TurtleUpgradeModellers.getModel(combo.rightUpgrade(), null, TurtleSide.RIGHT);
-            parts.add(transform(model.getModel(), transformation.compose(model.getMatrix())));
-        }
+
+        addUpgrade(parts, transformation, TurtleSide.LEFT, combo.leftUpgrade());
+        addUpgrade(parts, transformation, TurtleSide.RIGHT, combo.rightUpgrade());
 
         return parts;
     }
 
-    public BakedModel transform(BakedModel model, Transformation transformation) {
+    private void addUpgrade(List<BakedModel> parts, Transformation transformation, TurtleSide side, @Nullable UpgradeData<ITurtleUpgrade> upgrade) {
+        if (upgrade == null) return;
+        var model = TurtleUpgradeModellers.getModel(upgrade.upgrade(), upgrade.data(), side);
+        parts.add(transform(model.getModel(), transformation.compose(model.getMatrix())));
+    }
+
+    private BakedModel transform(BakedModel model, Transformation transformation) {
         if (transformation.equals(Transformation.identity())) return model;
         return transformCache.computeIfAbsent(new TransformedModel(model, transformation), transformer);
     }

projects/common/src/client/java/dan200/computercraft/client/render/TurtleBlockEntityRenderer.java

@@ -10,6 +10,7 @@ import com.mojang.math.Axis;
 import com.mojang.math.Transformation;
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.client.model.turtle.ModelTransformer;
 import dan200.computercraft.client.platform.ClientPlatformHelper;
 import dan200.computercraft.client.turtle.TurtleUpgradeModellers;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
@@ -30,6 +31,7 @@ import net.minecraft.resources.ResourceLocation;
 import net.minecraft.util.RandomSource;
 import net.minecraft.world.phys.BlockHitResult;
 import net.minecraft.world.phys.HitResult;
+import org.joml.Vector4f;
 
 import javax.annotation.Nullable;
 import java.util.List;
@@ -146,16 +148,30 @@ public class TurtleBlockEntityRenderer implements BlockEntityRenderer<TurtleBloc
         renderModel(transform, renderer, lightmapCoord, overlayLight, ClientPlatformHelper.get().getModel(modelManager, modelLocation), tints);
     }
 
+    /**
+     * Render a block model.
+     *
+     * @param transform     The current matrix stack.
+     * @param renderer      The buffer to write to.
+     * @param lightmapCoord The current lightmap coordinate.
+     * @param overlayLight  The overlay light.
+     * @param model         The model to render.
+     * @param tints         Tints for the quads, as an array of RGB values.
+     * @see net.minecraft.client.renderer.block.ModelBlockRenderer#renderModel
+     */
     private void renderModel(PoseStack transform, VertexConsumer renderer, int lightmapCoord, int overlayLight, BakedModel model, @Nullable int[] tints) {
-        random.setSeed(0);
-        renderQuads(transform, renderer, lightmapCoord, overlayLight, model.getQuads(null, null, random), tints);
         for (var facing : DirectionUtil.FACINGS) {
+            random.setSeed(42);
             renderQuads(transform, renderer, lightmapCoord, overlayLight, model.getQuads(null, facing, random), tints);
         }
+
+        random.setSeed(42);
+        renderQuads(transform, renderer, lightmapCoord, overlayLight, model.getQuads(null, null, random), tints);
     }
 
     private static void renderQuads(PoseStack transform, VertexConsumer buffer, int lightmapCoord, int overlayLight, List<BakedQuad> quads, @Nullable int[] tints) {
         var matrix = transform.last();
+        var inverted = matrix.pose().determinant() < 0;
 
         for (var bakedquad : quads) {
             var tint = -1;
@@ -167,7 +183,50 @@ public class TurtleBlockEntityRenderer implements BlockEntityRenderer<TurtleBloc
             var r = (float) (tint >> 16 & 255) / 255.0F;
             var g = (float) (tint >> 8 & 255) / 255.0F;
             var b = (float) (tint & 255) / 255.0F;
-            buffer.putBulkData(matrix, bakedquad, r, g, b, lightmapCoord, overlayLight);
+            if (inverted) {
+                putBulkQuadInvert(buffer, matrix, bakedquad, r, g, b, lightmapCoord, overlayLight);
+            } else {
+                buffer.putBulkData(matrix, bakedquad, r, g, b, lightmapCoord, overlayLight);
+            }
+        }
+    }
+
+    /**
+     * A version of {@link VertexConsumer#putBulkData(PoseStack.Pose, BakedQuad, float, float, float, int, int)} for
+     * when the matrix is inverted.
+     *
+     * @param buffer        The buffer to draw to.
+     * @param pose          The current matrix stack.
+     * @param quad          The quad to draw.
+     * @param red           The red tint of this quad.
+     * @param green         The  green tint of this quad.
+     * @param blue          The blue tint of this quad.
+     * @param lightmapCoord The lightmap coordinate
+     * @param overlayLight  The overlay light.
+     */
+    private static void putBulkQuadInvert(VertexConsumer buffer, PoseStack.Pose pose, BakedQuad quad, float red, float green, float blue, int lightmapCoord, int overlayLight) {
+        var matrix = pose.pose();
+        // It's a little dubious to transform using this matrix rather than the normal matrix. This mirrors the logic in
+        // Direction.rotate (so not out of nowhere!), but is a little suspicious.
+        var dirNormal = quad.getDirection().getNormal();
+        var normal = matrix.transform(new Vector4f(dirNormal.getX(), dirNormal.getY(), dirNormal.getZ(), 0.0f)).normalize();
+
+        var vertices = quad.getVertices();
+        for (var vertex : ModelTransformer.ORDER) {
+            var i = vertex * ModelTransformer.STRIDE;
+
+            var x = Float.intBitsToFloat(vertices[i]);
+            var y = Float.intBitsToFloat(vertices[i + 1]);
+            var z = Float.intBitsToFloat(vertices[i + 2]);
+            var transformed = matrix.transform(new Vector4f(x, y, z, 1));
+
+            var u = Float.intBitsToFloat(vertices[i + 4]);
+            var v = Float.intBitsToFloat(vertices[i + 5]);
+            buffer.vertex(
+                transformed.x(), transformed.y(), transformed.z(),
+                red, green, blue, 1.0F, u, v, overlayLight, lightmapCoord,
+                normal.x(), normal.y(), normal.z()
+            );
         }
     }
 

projects/common/src/client/java/dan200/computercraft/client/turtle/TurtleUpgradeModellers.java

@@ -14,8 +14,8 @@ import dan200.computercraft.api.turtle.TurtleUpgradeSerialiser;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.impl.UpgradeManager;
 import net.minecraft.client.Minecraft;
+import net.minecraft.nbt.CompoundTag;
 
-import javax.annotation.Nullable;
 import java.util.Map;
 import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
@@ -52,12 +52,18 @@ public final class TurtleUpgradeModellers {
         }
     }
 
-    public static TransformedModel getModel(ITurtleUpgrade upgrade, @Nullable ITurtleAccess access, TurtleSide side) {
+    public static TransformedModel getModel(ITurtleUpgrade upgrade, ITurtleAccess access, TurtleSide side) {
         @SuppressWarnings("unchecked")
         var modeller = (TurtleUpgradeModeller<ITurtleUpgrade>) modelCache.computeIfAbsent(upgrade, TurtleUpgradeModellers::getModeller);
         return modeller.getModel(upgrade, access, side);
     }
 
+    public static TransformedModel getModel(ITurtleUpgrade upgrade, CompoundTag data, TurtleSide side) {
+        @SuppressWarnings("unchecked")
+        var modeller = (TurtleUpgradeModeller<ITurtleUpgrade>) modelCache.computeIfAbsent(upgrade, TurtleUpgradeModellers::getModeller);
+        return modeller.getModel(upgrade, data, side);
+    }
+
     private static TurtleUpgradeModeller<?> getModeller(ITurtleUpgrade upgradeA) {
         var wrapper = TurtleUpgrades.instance().getWrapper(upgradeA);
         if (wrapper == null) return NULL_TURTLE_MODELLER;

projects/common/src/client/java/dan200/computercraft/data/client/ClientDataProviders.java

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.data.client;
+
+import dan200.computercraft.data.DataProviders;
+import dan200.computercraft.shared.turtle.inventory.UpgradeSlot;
+import net.minecraft.client.renderer.texture.atlas.SpriteSources;
+import net.minecraft.client.renderer.texture.atlas.sources.SingleFile;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.PackType;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * A version of {@link DataProviders} which relies on client-side classes.
+ * <p>
+ * This is called from {@link DataProviders#add(DataProviders.GeneratorSink)}.
+ */
+public final class ClientDataProviders {
+    private ClientDataProviders() {
+    }
+
+    public static void add(DataProviders.GeneratorSink generator) {
+        generator.addFromCodec("Block atlases", PackType.CLIENT_RESOURCES, "atlases", SpriteSources.FILE_CODEC, out -> {
+            out.accept(new ResourceLocation("blocks"), List.of(
+                new SingleFile(UpgradeSlot.LEFT_UPGRADE, Optional.empty()),
+                new SingleFile(UpgradeSlot.RIGHT_UPGRADE, Optional.empty())
+            ));
+        });
+    }
+}

projects/common/src/main/java/dan200/computercraft/data/BlockModelProvider.java

@@ -37,6 +37,14 @@ import static net.minecraft.data.models.model.ModelLocationUtils.getModelLocatio
 import static net.minecraft.data.models.model.TextureMapping.getBlockTexture;
 
 class BlockModelProvider {
+    private static final TextureSlot CURSOR = TextureSlot.create("cursor");
+
+    private static final ModelTemplate COMPUTER_ON = new ModelTemplate(
+        Optional.of(new ResourceLocation(ComputerCraftAPI.MOD_ID, "block/computer_on")),
+        Optional.empty(),
+        TextureSlot.FRONT, TextureSlot.SIDE, TextureSlot.TOP, CURSOR
+    );
+
     private static final ModelTemplate MONITOR_BASE = new ModelTemplate(
         Optional.of(new ResourceLocation(ComputerCraftAPI.MOD_ID, "block/monitor_base")),
         Optional.empty(),
@@ -142,11 +150,18 @@ class BlockModelProvider {
     private static void registerComputer(BlockModelGenerators generators, ComputerBlock<?> block) {
         generators.blockStateOutput.accept(MultiVariantGenerator.multiVariant(block)
             .with(createHorizontalFacingDispatch())
-            .with(createModelDispatch(ComputerBlock.STATE, state -> ModelTemplates.CUBE_ORIENTABLE.createWithSuffix(
-                block, "_" + state.getSerializedName(),
-                TextureMapping.orientableCube(block).put(TextureSlot.FRONT, getBlockTexture(block, "_front" + state.getTexture())),
-                generators.modelOutput
-            )))
+            .with(createModelDispatch(ComputerBlock.STATE, state -> switch (state) {
+                case OFF -> ModelTemplates.CUBE_ORIENTABLE.createWithSuffix(
+                    block, "_" + state.getSerializedName(),
+                    TextureMapping.orientableCube(block),
+                    generators.modelOutput
+                );
+                case ON, BLINKING -> COMPUTER_ON.createWithSuffix(
+                    block, "_" + state.getSerializedName(),
+                    TextureMapping.orientableCube(block).put(CURSOR, new ResourceLocation(ComputerCraftAPI.MOD_ID, "block/computer" + state.getTexture())),
+                    generators.modelOutput
+                );
+            }))
         );
         generators.delegateItemModel(block, getModelLocation(block, "_blinking"));
     }

projects/common/src/main/java/dan200/computercraft/data/DataProviders.java

@@ -4,16 +4,20 @@
 
 package dan200.computercraft.data;
 
+import com.mojang.serialization.Codec;
 import net.minecraft.data.DataProvider;
 import net.minecraft.data.PackOutput;
 import net.minecraft.data.loot.LootTableProvider.SubProviderEntry;
 import net.minecraft.data.models.BlockModelGenerators;
 import net.minecraft.data.models.ItemModelGenerators;
 import net.minecraft.data.tags.TagsProvider;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.PackType;
 import net.minecraft.world.item.Item;
 import net.minecraft.world.level.block.Block;
 
 import java.util.List;
+import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 
 /**
@@ -37,11 +41,22 @@ public final class DataProviders {
         generator.models(BlockModelProvider::addBlockModels, ItemModelProvider::addItemModels);
 
         generator.add(out -> new LanguageProvider(out, turtleUpgrades, pocketUpgrades));
+
+        // Unfortunately we rely on some client-side classes in this code. We just load in the client side data provider
+        // and invoke that.
+        try {
+            Class.forName("dan200.computercraft.data.client.ClientDataProviders")
+                .getMethod("add", GeneratorSink.class).invoke(null, generator);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
     }
 
-    interface GeneratorSink {
+    public interface GeneratorSink {
         <T extends DataProvider> T add(DataProvider.Factory<T> factory);
 
+        <T> void addFromCodec(String name, PackType type, String directory, Codec<T> codec, Consumer<BiConsumer<ResourceLocation, T>> output);
+
         void lootTable(List<SubProviderEntry> tables);
 
         TagsProvider<Block> blockTags(Consumer<TagProvider.TagConsumer<Block>> tags);

projects/common/src/main/java/dan200/computercraft/data/RecipeProvider.java

@@ -8,6 +8,7 @@ import com.google.gson.JsonObject;
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.pocket.PocketUpgradeDataProvider;
 import dan200.computercraft.api.turtle.TurtleUpgradeDataProvider;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.util.Colour;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.common.IColouredItem;
@@ -110,7 +111,7 @@ class RecipeProvider extends net.minecraft.data.recipes.RecipeProvider {
             var nameId = turtleItem.getFamily().name().toLowerCase(Locale.ROOT);
 
             for (var upgrade : turtleUpgrades.getGeneratedUpgrades()) {
-                var result = turtleItem.create(-1, null, -1, null, upgrade, -1, null);
+                var result = turtleItem.create(-1, null, -1, null, UpgradeData.ofDefault(upgrade), -1, null);
                 ShapedRecipeBuilder
                     .shaped(RecipeCategory.REDSTONE, result.getItem())
                     .group(String.format("%s:turtle_%s", ComputerCraftAPI.MOD_ID, nameId))
@@ -146,7 +147,7 @@ class RecipeProvider extends net.minecraft.data.recipes.RecipeProvider {
             var nameId = pocket.getFamily().name().toLowerCase(Locale.ROOT);
 
             for (var upgrade : pocketUpgrades.getGeneratedUpgrades()) {
-                var result = pocket.create(-1, null, -1, upgrade);
+                var result = pocket.create(-1, null, -1, UpgradeData.ofDefault(upgrade));
                 ShapedRecipeBuilder
                     .shaped(RecipeCategory.REDSTONE, result.getItem())
                     .group(String.format("%s:pocket_%s", ComputerCraftAPI.MOD_ID, nameId))

projects/common/src/main/java/dan200/computercraft/impl/AbstractComputerCraftAPI.java

@@ -19,8 +19,6 @@ import dan200.computercraft.api.pocket.PocketUpgradeSerialiser;
 import dan200.computercraft.api.redstone.BundledRedstoneProvider;
 import dan200.computercraft.api.turtle.TurtleRefuelHandler;
 import dan200.computercraft.api.turtle.TurtleUpgradeSerialiser;
-import dan200.computercraft.core.apis.ApiFactories;
-import dan200.computercraft.core.asm.GenericMethod;
 import dan200.computercraft.core.filesystem.WritableFileMount;
 import dan200.computercraft.impl.detail.DetailRegistryImpl;
 import dan200.computercraft.impl.network.wired.WiredNodeImpl;
@@ -79,7 +77,7 @@ public abstract class AbstractComputerCraftAPI implements ComputerCraftAPIServic
 
     @Override
     public final void registerGenericSource(GenericSource source) {
-        GenericMethod.register(source);
+        GenericSources.register(source);
     }
 
     @Override

projects/common/src/main/java/dan200/computercraft/impl/ApiFactories.java

@@ -2,7 +2,7 @@
 //
 // SPDX-License-Identifier: MPL-2.0
 
-package dan200.computercraft.core.apis;
+package dan200.computercraft.impl;
 
 import dan200.computercraft.api.lua.ILuaAPIFactory;
 
@@ -11,19 +11,24 @@ import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Objects;
 
+/**
+ * The global factory for {@link ILuaAPIFactory}s.
+ *
+ * @see dan200.computercraft.core.ComputerContext.Builder#apiFactories(Collection)
+ * @see dan200.computercraft.api.ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
+ */
 public final class ApiFactories {
     private ApiFactories() {
     }
 
     private static final Collection<ILuaAPIFactory> factories = new LinkedHashSet<>();
-    private static final Collection<ILuaAPIFactory> factoriesView = Collections.unmodifiableCollection(factories);
 
-    public static synchronized void register(ILuaAPIFactory factory) {
+    static synchronized void register(ILuaAPIFactory factory) {
         Objects.requireNonNull(factory, "provider cannot be null");
         factories.add(factory);
     }
 
-    public static Iterable<ILuaAPIFactory> getAll() {
-        return factoriesView;
+    public static Collection<ILuaAPIFactory> getAll() {
+        return Collections.unmodifiableCollection(factories);
     }
 }

projects/common/src/main/java/dan200/computercraft/impl/GenericSources.java

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.impl;
+
+import dan200.computercraft.api.lua.GenericSource;
+import dan200.computercraft.core.asm.GenericMethod;
+
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.Objects;
+
+/**
+ * The global registry for {@link GenericSource}s.
+ *
+ * @see dan200.computercraft.core.ComputerContext.Builder#genericMethods(Collection)
+ * @see dan200.computercraft.api.ComputerCraftAPI#registerGenericSource(GenericSource)
+ */
+public final class GenericSources {
+    private GenericSources() {
+    }
+
+    private static final Collection<GenericSource> sources = new LinkedHashSet<>();
+
+    static synchronized void register(GenericSource source) {
+        Objects.requireNonNull(source, "provider cannot be null");
+        sources.add(source);
+    }
+
+    public static Collection<GenericMethod> getAllMethods() {
+        return sources.stream().flatMap(GenericMethod::getMethods).toList();
+    }
+}

projects/common/src/main/java/dan200/computercraft/impl/UpgradeManager.java

@@ -7,6 +7,7 @@ package dan200.computercraft.impl;
 import com.google.gson.*;
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.upgrades.UpgradeBase;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.api.upgrades.UpgradeSerialiser;
 import dan200.computercraft.shared.platform.PlatformHelper;
 import net.minecraft.core.Registry;
@@ -74,13 +75,13 @@ public class UpgradeManager<R extends UpgradeSerialiser<? extends T>, T extends
     }
 
     @Nullable
-    public T get(ItemStack stack) {
+    public UpgradeData<T> get(ItemStack stack) {
         if (stack.isEmpty()) return null;
 
         for (var wrapper : current.values()) {
             var craftingStack = wrapper.upgrade().getCraftingItem();
             if (!craftingStack.isEmpty() && craftingStack.getItem() == stack.getItem() && wrapper.upgrade().isItemSuitable(stack)) {
-                return wrapper.upgrade();
+                return UpgradeData.of(wrapper.upgrade, wrapper.upgrade.getUpgradeData(stack));
             }
         }
 

projects/common/src/main/java/dan200/computercraft/shared/ModRegistry.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.detail.VanillaDetailRegistries;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.pocket.PocketUpgradeSerialiser;
 import dan200.computercraft.api.turtle.TurtleUpgradeSerialiser;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.util.Colour;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.impl.TurtleUpgrades;
@@ -446,12 +447,12 @@ public final class ModRegistry {
     private static void addTurtle(CreativeModeTab.Output out, TurtleItem turtle) {
         out.accept(turtle.create(-1, null, -1, null, null, 0, null));
         TurtleUpgrades.getVanillaUpgrades()
-            .map(x -> turtle.create(-1, null, -1, null, x, 0, null))
+            .map(x -> turtle.create(-1, null, -1, null, UpgradeData.ofDefault(x), 0, null))
             .forEach(out::accept);
     }
 
     private static void addPocket(CreativeModeTab.Output out, PocketComputerItem pocket) {
         out.accept(pocket.create(-1, null, -1, null));
-        PocketUpgrades.getVanillaUpgrades().map(x -> pocket.create(-1, null, -1, x)).forEach(out::accept);
+        PocketUpgrades.getVanillaUpgrades().map(x -> pocket.create(-1, null, -1, UpgradeData.ofDefault(x))).forEach(out::accept);
     }
 }

projects/common/src/main/java/dan200/computercraft/shared/command/arguments/ComputersArgumentType.java

@@ -18,7 +18,6 @@ import net.minecraft.commands.CommandBuildContext;
 import net.minecraft.commands.CommandSourceStack;
 import net.minecraft.commands.synchronization.ArgumentTypeInfo;
 import net.minecraft.network.FriendlyByteBuf;
-import org.jetbrains.annotations.NotNull;
 
 import java.util.*;
 import java.util.concurrent.CompletableFuture;
@@ -159,14 +158,14 @@ public final class ComputersArgumentType implements ArgumentType<ComputersArgume
         }
 
         @Override
-        public ComputersArgumentType.Template unpack(@NotNull ComputersArgumentType argumentType) {
+        public ComputersArgumentType.Template unpack(ComputersArgumentType argumentType) {
             return new ComputersArgumentType.Template(this, argumentType.requireSome);
         }
     }
 
     public record Template(Info info, boolean requireSome) implements ArgumentTypeInfo.Template<ComputersArgumentType> {
         @Override
-        public ComputersArgumentType instantiate(@NotNull CommandBuildContext context) {
+        public ComputersArgumentType instantiate(CommandBuildContext context) {
             return requireSome ? SOME : MANY;
         }
 

projects/common/src/main/java/dan200/computercraft/shared/command/arguments/RepeatArgumentType.java

@@ -17,7 +17,6 @@ import net.minecraft.commands.synchronization.ArgumentTypeInfo;
 import net.minecraft.commands.synchronization.ArgumentTypeInfos;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.network.chat.Component;
-import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -144,7 +143,7 @@ public final class RepeatArgumentType<T, U> implements ArgumentType<List<T>> {
     ) implements ArgumentTypeInfo.Template<RepeatArgumentType<?, ?>> {
         @Override
         @SuppressWarnings({ "unchecked", "rawtypes" })
-        public RepeatArgumentType<?, ?> instantiate(@NotNull CommandBuildContext commandBuildContext) {
+        public RepeatArgumentType<?, ?> instantiate(CommandBuildContext commandBuildContext) {
             var child = child().instantiate(commandBuildContext);
             return flatten ? RepeatArgumentType.someFlat((ArgumentType) child, some()) : RepeatArgumentType.some(child, some());
         }

projects/common/src/main/java/dan200/computercraft/shared/computer/core/ServerContext.java

@@ -9,13 +9,16 @@ import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.filesystem.Mount;
 import dan200.computercraft.api.network.PacketNetwork;
 import dan200.computercraft.core.ComputerContext;
-import dan200.computercraft.core.computer.ComputerThread;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.computer.mainthread.MainThread;
 import dan200.computercraft.core.computer.mainthread.MainThreadConfig;
 import dan200.computercraft.core.lua.CobaltLuaMachine;
 import dan200.computercraft.core.lua.ILuaMachine;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.impl.AbstractComputerCraftAPI;
+import dan200.computercraft.impl.ApiFactories;
+import dan200.computercraft.impl.GenericSources;
 import dan200.computercraft.shared.CommonHooks;
 import dan200.computercraft.shared.computer.metrics.GlobalMetrics;
 import dan200.computercraft.shared.config.ConfigSpec;
@@ -67,11 +70,13 @@ public final class ServerContext {
         this.server = server;
         storageDir = server.getWorldPath(FOLDER);
         mainThread = new MainThread(mainThreadConfig);
-        context = new ComputerContext(
-            new Environment(server),
-            new ComputerThread(ConfigSpec.computerThreads.get()),
-            mainThread, luaMachine
-        );
+        context = ComputerContext.builder(new Environment(server))
+            .computerThreads(ConfigSpec.computerThreads.get())
+            .mainThreadScheduler(mainThread)
+            .luaFactory(luaMachine)
+            .apiFactories(ApiFactories.getAll())
+            .genericMethods(GenericSources.getAllMethods())
+            .build();
         idAssigner = new IDAssigner(storageDir.resolve("ids.json"));
     }
 
@@ -133,6 +138,16 @@ public final class ServerContext {
         return context;
     }
 
+    /**
+     * Get the {@link MethodSupplier} used to find methods on peripherals.
+     *
+     * @return The {@link PeripheralMethod} method supplier.
+     * @see ComputerContext#peripheralMethods()
+     */
+    public MethodSupplier<PeripheralMethod> peripheralMethods() {
+        return context.peripheralMethods();
+    }
+
     /**
      * Tick all components of this server context. This should <em>NOT</em> be called outside of {@link CommonHooks}.
      */

projects/common/src/main/java/dan200/computercraft/shared/computer/upload/TransferredFile.java

@@ -7,7 +7,7 @@ package dan200.computercraft.shared.computer.upload;
 import dan200.computercraft.api.lua.LuaFunction;
 import dan200.computercraft.core.apis.handles.BinaryReadableHandle;
 import dan200.computercraft.core.apis.handles.ByteBufferChannel;
-import dan200.computercraft.core.asm.ObjectSource;
+import dan200.computercraft.core.methods.ObjectSource;
 
 import java.nio.ByteBuffer;
 import java.util.Collections;

projects/common/src/main/java/dan200/computercraft/shared/config/AddressRuleConfig.java

@@ -4,21 +4,19 @@
 
 package dan200.computercraft.shared.config;
 
+import com.electronwill.nightconfig.core.CommentedConfig;
 import com.electronwill.nightconfig.core.Config;
 import com.electronwill.nightconfig.core.InMemoryCommentedFormat;
 import com.electronwill.nightconfig.core.UnmodifiableConfig;
 import dan200.computercraft.core.apis.http.options.Action;
 import dan200.computercraft.core.apis.http.options.AddressRule;
+import dan200.computercraft.core.apis.http.options.InvalidRuleException;
 import dan200.computercraft.core.apis.http.options.PartialOptions;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import javax.annotation.Nullable;
-import java.util.Locale;
-import java.util.Optional;
-import java.util.OptionalInt;
-import java.util.OptionalLong;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.*;
+import java.util.function.Consumer;
 
 /**
  * Parses, checks and generates {@link Config}s for {@link AddressRule}.
@@ -26,49 +24,65 @@ import java.util.concurrent.ConcurrentHashMap;
 class AddressRuleConfig {
     private static final Logger LOG = LoggerFactory.getLogger(AddressRuleConfig.class);
 
-    public static UnmodifiableConfig makeRule(String host, Action action) {
-        var config = InMemoryCommentedFormat.defaultInstance().createConfig(ConcurrentHashMap::new);
-        config.add("host", host);
-        config.add("action", action.name().toLowerCase(Locale.ROOT));
+    private static final AddressRule REJECT_ALL = AddressRule.parse("*", OptionalInt.empty(), Action.DENY.toPartial());
 
-        if (host.equals("*") && action == Action.ALLOW) {
-            config.setComment("max_download", """
-                The maximum size (in bytes) that a computer can download in a single request.
-                Note that responses may receive more data than allowed, but this data will not
-                be returned to the client.""");
-            config.set("max_download", AddressRule.MAX_DOWNLOAD);
+    public static List<UnmodifiableConfig> defaultRules() {
+        return List.of(
+            makeRule(config -> {
+                config.setComment("host", """
+                    The magic "$private" host matches all private address ranges, such as localhost and 192.168.0.0/16.
+                    This rule prevents computers accessing internal services, and is strongly recommended.""");
+                config.add("host", "$private");
 
-            config.setComment("max_upload", """
-                The maximum size (in bytes) that a computer can upload in a single request. This
-                includes headers and POST text.""");
-            config.set("max_upload", AddressRule.MAX_UPLOAD);
+                config.setComment("action", "Deny all requests to private IP addresses.");
+                config.add("action", Action.DENY.name().toLowerCase(Locale.ROOT));
+            }),
+            makeRule(config -> {
+                config.setComment("host", """
+                    The wildcard "*" rule matches all remaining hosts.""");
+                config.add("host", "*");
 
-            config.setComment("max_websocket_message", "The maximum size (in bytes) that a computer can send or receive in one websocket packet.");
-            config.set("max_websocket_message", AddressRule.WEBSOCKET_MESSAGE);
+                config.setComment("action", "Allow all non-denied hosts.");
+                config.add("action", Action.ALLOW.name().toLowerCase(Locale.ROOT));
 
-            config.setComment("use_proxy", "Enable use of the HTTP/SOCKS proxy if it is configured.");
-            config.set("use_proxy", false);
-        }
+                config.setComment("max_download", """
+                    The maximum size (in bytes) that a computer can download in a single request.
+                    Note that responses may receive more data than allowed, but this data will not
+                    be returned to the client.""");
+                config.set("max_download", AddressRule.MAX_DOWNLOAD);
 
+                config.setComment("max_upload", """
+                    The maximum size (in bytes) that a computer can upload in a single request. This
+                    includes headers and POST text.""");
+                config.set("max_upload", AddressRule.MAX_UPLOAD);
+
+                config.setComment("max_websocket_message", "The maximum size (in bytes) that a computer can send or receive in one websocket packet.");
+                config.set("max_websocket_message", AddressRule.WEBSOCKET_MESSAGE);
+
+                config.setComment("use_proxy", "Enable use of the HTTP/SOCKS proxy if it is configured.");
+                config.set("use_proxy", false);
+            })
+        );
+    }
+
+    private static UnmodifiableConfig makeRule(Consumer<CommentedConfig> setup) {
+        var config = InMemoryCommentedFormat.defaultInstance().createConfig(LinkedHashMap::new);
+        setup.accept(config);
         return config;
     }
 
-    public static boolean checkRule(UnmodifiableConfig builder) {
-        var hostObj = get(builder, "host", String.class).orElse(null);
-        var port = unboxOptInt(get(builder, "port", Number.class));
-        return hostObj != null && checkEnum(builder, "action", Action.class)
-            && check(builder, "port", Number.class)
-            && check(builder, "max_upload", Number.class)
-            && check(builder, "max_download", Number.class)
-            && check(builder, "websocket_message", Number.class)
-            && check(builder, "use_proxy", Boolean.class)
-            && AddressRule.parse(hostObj, port, PartialOptions.DEFAULT) != null;
+    public static AddressRule parseRule(UnmodifiableConfig builder) {
+        try {
+            return doParseRule(builder);
+        } catch (InvalidRuleException e) {
+            LOG.error("Malformed HTTP rule: {} HTTP will NOT work until this is fixed.", e.getMessage());
+            return REJECT_ALL;
+        }
     }
 
-    @Nullable
-    public static AddressRule parseRule(UnmodifiableConfig builder) {
+    public static AddressRule doParseRule(UnmodifiableConfig builder) {
         var hostObj = get(builder, "host", String.class).orElse(null);
-        if (hostObj == null) return null;
+        if (hostObj == null) throw new InvalidRuleException("No 'host' specified");
 
         var action = getEnum(builder, "action", Action.class).orElse(null);
         var port = unboxOptInt(get(builder, "port", Number.class));
@@ -88,38 +102,19 @@ class AddressRuleConfig {
         return AddressRule.parse(hostObj, port, options);
     }
 
-    private static <T> boolean check(UnmodifiableConfig config, String field, Class<T> klass) {
-        var value = config.get(field);
-        if (value == null || klass.isInstance(value)) return true;
-
-        LOG.warn("HTTP rule's {} is not a {}.", field, klass.getSimpleName());
-        return false;
-    }
-
-    private static <T extends Enum<T>> boolean checkEnum(UnmodifiableConfig config, String field, Class<T> klass) {
-        var value = config.get(field);
-        if (value == null) return true;
-
-        if (!(value instanceof String)) {
-            LOG.warn("HTTP rule's {} is not a string", field);
-            return false;
-        }
-
-        if (parseEnum(klass, (String) value) == null) {
-            LOG.warn("HTTP rule's {} is not a known option", field);
-            return false;
-        }
-
-        return true;
-    }
-
     private static <T> Optional<T> get(UnmodifiableConfig config, String field, Class<T> klass) {
         var value = config.get(field);
-        return klass.isInstance(value) ? Optional.of(klass.cast(value)) : Optional.empty();
+        if (value == null) return Optional.empty();
+        if (klass.isInstance(value)) return Optional.of(klass.cast(value));
+
+        throw new InvalidRuleException(String.format(
+            "Field '%s' should be a '%s' but is a %s.",
+            field, klass.getSimpleName(), value.getClass().getSimpleName()
+        ));
     }
 
     private static <T extends Enum<T>> Optional<T> getEnum(UnmodifiableConfig config, String field, Class<T> klass) {
-        return get(config, field, String.class).map(x -> parseEnum(klass, x));
+        return get(config, field, String.class).map(x -> parseEnum(field, klass, x));
     }
 
     private static OptionalLong unboxOptLong(Optional<? extends Number> value) {
@@ -130,11 +125,14 @@ class AddressRuleConfig {
         return value.map(Number::intValue).map(OptionalInt::of).orElse(OptionalInt.empty());
     }
 
-    @Nullable
-    private static <T extends Enum<T>> T parseEnum(Class<T> klass, String x) {
+    private static <T extends Enum<T>> T parseEnum(String field, Class<T> klass, String x) {
         for (var value : klass.getEnumConstants()) {
             if (value.name().equalsIgnoreCase(x)) return value;
         }
-        return null;
+
+        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
+        ));
     }
 }

projects/common/src/main/java/dan200/computercraft/shared/config/ConfigSpec.java

@@ -9,7 +9,6 @@ import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.core.CoreConfig;
 import dan200.computercraft.core.Logging;
 import dan200.computercraft.core.apis.http.NetworkUtils;
-import dan200.computercraft.core.apis.http.options.Action;
 import dan200.computercraft.core.apis.http.options.ProxyType;
 import dan200.computercraft.core.computer.mainthread.MainThreadConfig;
 import dan200.computercraft.shared.peripheral.monitor.MonitorRenderer;
@@ -20,9 +19,7 @@ import org.apache.logging.log4j.core.filter.MarkerFilter;
 
 import javax.annotation.Nullable;
 import java.nio.file.Path;
-import java.util.Arrays;
 import java.util.List;
-import java.util.Objects;
 import java.util.concurrent.TimeUnit;
 
 public final class ConfigSpec {
@@ -182,9 +179,9 @@ public final class ConfigSpec {
 
             httpEnabled = builder
                 .comment("""
-                    Enable the "http" API on Computers. This also disables the "pastebin" and "wget"
-                    programs, that many users rely on. It's recommended to leave this on and use the
-                    "rules" config option to impose more fine-grained control.""")
+                    Enable the "http" API on Computers. Disabling this also disables the "pastebin" and
+                    "wget" programs, that many users rely on. It's recommended to leave this on and use
+                    the "rules" config option to impose more fine-grained control.""")
                 .define("enabled", CoreConfig.httpEnabled);
 
             httpWebsocketEnabled = builder
@@ -194,16 +191,23 @@ public final class ConfigSpec {
             httpRules = builder
                 .comment("""
                     A list of rules which control behaviour of the "http" API for specific domains or
-                    IPs. Each rule is an item with a 'host' to match against, and a series of
-                    properties. Rules are evaluated in order, meaning earlier rules override later
-                    ones.
-                    The host may be a domain name ("pastebin.com"), wildcard ("*.pastebin.com") or
-                    CIDR notation ("127.0.0.0/8").
-                    If no rules, the domain is blocked.""")
-                .defineList("rules", Arrays.asList(
-                    AddressRuleConfig.makeRule("$private", Action.DENY),
-                    AddressRuleConfig.makeRule("*", Action.ALLOW)
-                ), x -> x instanceof UnmodifiableConfig && AddressRuleConfig.checkRule((UnmodifiableConfig) x));
+                    IPs. Each rule matches against a hostname and an optional port, and then sets several
+                    properties for the request.  Rules are evaluated in order, meaning earlier rules override
+                    later ones.
+
+                    Valid properties:
+                     - "host" (required): The domain or IP address this rule matches. This may be a domain name
+                       ("pastebin.com"), wildcard ("*.pastebin.com") or CIDR notation ("127.0.0.0/8").
+                     - "port" (optional): Only match requests for a specific port, such as 80 or 443.
+
+                     - "action" (optional): Whether to allow or deny this request.
+                     - "max_download" (optional): The maximum size (in bytes) that a computer can download in this
+                       request.
+                     - "max_upload" (optional): The maximum size (in bytes) that a computer can upload in a this request.
+                     - "max_websocket_message" (optional): The maximum size (in bytes) that a computer can send or
+                       receive in one websocket packet.
+                     - "use_proxy" (optional): Enable use of the HTTP/SOCKS proxy if it is configured.""")
+                .defineList("rules", AddressRuleConfig.defaultRules(), x -> x instanceof UnmodifiableConfig);
 
             httpMaxRequests = builder
                 .comment("""
@@ -395,8 +399,8 @@ public final class ConfigSpec {
         // HTTP
         CoreConfig.httpEnabled = httpEnabled.get();
         CoreConfig.httpWebsocketEnabled = httpWebsocketEnabled.get();
-        CoreConfig.httpRules = httpRules.get().stream()
-            .map(AddressRuleConfig::parseRule).filter(Objects::nonNull).toList();
+
+        CoreConfig.httpRules = httpRules.get().stream().map(AddressRuleConfig::parseRule).toList();
 
         CoreConfig.httpMaxRequests = httpMaxRequests.get();
         CoreConfig.httpMaxWebsockets = httpMaxWebsockets.get();

projects/common/src/main/java/dan200/computercraft/shared/container/BasicContainer.java

@@ -7,7 +7,6 @@ package dan200.computercraft.shared.container;
 import net.minecraft.core.NonNullList;
 import net.minecraft.world.Container;
 import net.minecraft.world.ContainerHelper;
-import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.item.ItemStack;
 
 /**
@@ -16,24 +15,6 @@ import net.minecraft.world.item.ItemStack;
 public interface BasicContainer extends Container {
     NonNullList<ItemStack> getContents();
 
-    @Override
-    default int getMaxStackSize() {
-        return 64;
-    }
-
-    @Override
-    default void startOpen(Player player) {
-    }
-
-    @Override
-    default void stopOpen(Player player) {
-    }
-
-    @Override
-    default boolean canPlaceItem(int slot, ItemStack stack) {
-        return true;
-    }
-
     @Override
     default int getContainerSize() {
         return getContents().size();

projects/common/src/main/java/dan200/computercraft/shared/integration/RecipeModHelpers.java

@@ -5,6 +5,7 @@
 package dan200.computercraft.shared.integration;
 
 import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.ModRegistry;
@@ -56,14 +57,14 @@ public final class RecipeModHelpers {
         for (var turtleSupplier : TURTLES) {
             var turtle = turtleSupplier.get();
             for (var upgrade : TurtleUpgrades.instance().getUpgrades()) {
-                upgradeItems.add(turtle.create(-1, null, -1, null, upgrade, 0, null));
+                upgradeItems.add(turtle.create(-1, null, -1, null, UpgradeData.ofDefault(upgrade), 0, null));
             }
         }
 
         for (var pocketSupplier : POCKET_COMPUTERS) {
             var pocket = pocketSupplier.get();
             for (var upgrade : PocketUpgrades.instance().getUpgrades()) {
-                upgradeItems.add(pocket.create(-1, null, -1, upgrade));
+                upgradeItems.add(pocket.create(-1, null, -1, UpgradeData.ofDefault(upgrade)));
             }
         }
 

projects/common/src/main/java/dan200/computercraft/shared/integration/UpgradeRecipeGenerator.java

@@ -9,6 +9,7 @@ import dan200.computercraft.api.pocket.IPocketUpgrade;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.api.upgrades.UpgradeBase;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.pocket.items.PocketComputerItem;
@@ -111,20 +112,22 @@ public class UpgradeRecipeGenerator<T> {
 
         if (stack.getItem() instanceof TurtleItem item) {
             // Suggest possible upgrades which can be applied to this turtle
-            var left = item.getUpgrade(stack, TurtleSide.LEFT);
-            var right = item.getUpgrade(stack, TurtleSide.RIGHT);
+            var left = item.getUpgradeWithData(stack, TurtleSide.LEFT);
+            var right = item.getUpgradeWithData(stack, TurtleSide.RIGHT);
             if (left != null && right != null) return Collections.emptyList();
 
             List<T> recipes = new ArrayList<>();
             var ingredient = Ingredient.of(stack);
             for (var upgrade : turtleUpgrades) {
+                if (upgrade.turtle == null) throw new NullPointerException();
+
                 // The turtle is facing towards us, so upgrades on the left are actually crafted on the right.
                 if (left == null) {
-                    recipes.add(turtle(ingredient, upgrade.ingredient, turtleWith(stack, upgrade.turtle, right)));
+                    recipes.add(turtle(ingredient, upgrade.ingredient, turtleWith(stack, UpgradeData.ofDefault(upgrade.turtle), right)));
                 }
 
                 if (right == null) {
-                    recipes.add(turtle(upgrade.ingredient, ingredient, turtleWith(stack, left, upgrade.turtle)));
+                    recipes.add(turtle(upgrade.ingredient, ingredient, turtleWith(stack, left, UpgradeData.ofDefault(upgrade.turtle))));
                 }
             }
 
@@ -137,7 +140,8 @@ public class UpgradeRecipeGenerator<T> {
             List<T> recipes = new ArrayList<>();
             var ingredient = Ingredient.of(stack);
             for (var upgrade : pocketUpgrades) {
-                recipes.add(pocket(upgrade.ingredient, ingredient, pocketWith(stack, upgrade.pocket)));
+                if (upgrade.pocket == null) throw new NullPointerException();
+                recipes.add(pocket(upgrade.ingredient, ingredient, pocketWith(stack, UpgradeData.ofDefault(upgrade.pocket))));
             }
 
             return Collections.unmodifiableList(recipes);
@@ -180,21 +184,21 @@ public class UpgradeRecipeGenerator<T> {
         if (stack.getItem() instanceof TurtleItem item) {
             List<T> recipes = new ArrayList<>(0);
 
-            var left = item.getUpgrade(stack, TurtleSide.LEFT);
-            var right = item.getUpgrade(stack, TurtleSide.RIGHT);
+            var left = item.getUpgradeWithData(stack, TurtleSide.LEFT);
+            var right = item.getUpgradeWithData(stack, TurtleSide.RIGHT);
 
             // The turtle is facing towards us, so upgrades on the left are actually crafted on the right.
             if (left != null) {
                 recipes.add(turtle(
                     Ingredient.of(turtleWith(stack, null, right)),
-                    Ingredient.of(left.getCraftingItem()),
+                    Ingredient.of(left.getUpgradeItem()),
                     stack
                 ));
             }
 
             if (right != null) {
                 recipes.add(turtle(
-                    Ingredient.of(right.getCraftingItem()),
+                    Ingredient.of(right.getUpgradeItem()),
                     Ingredient.of(turtleWith(stack, left, null)),
                     stack
                 ));
@@ -204,9 +208,9 @@ public class UpgradeRecipeGenerator<T> {
         } else if (stack.getItem() instanceof PocketComputerItem) {
             List<T> recipes = new ArrayList<>(0);
 
-            var back = PocketComputerItem.getUpgrade(stack);
+            var back = PocketComputerItem.getUpgradeWithData(stack);
             if (back != null) {
-                recipes.add(pocket(Ingredient.of(back.getCraftingItem()), Ingredient.of(pocketWith(stack, null)), stack));
+                recipes.add(pocket(Ingredient.of(back.getUpgradeItem()), Ingredient.of(pocketWith(stack, null)), stack));
             }
 
             return Collections.unmodifiableList(recipes);
@@ -215,7 +219,7 @@ public class UpgradeRecipeGenerator<T> {
         }
     }
 
-    private static ItemStack turtleWith(ItemStack stack, @Nullable ITurtleUpgrade left, @Nullable ITurtleUpgrade right) {
+    private static ItemStack turtleWith(ItemStack stack, @Nullable UpgradeData<ITurtleUpgrade> left, @Nullable UpgradeData<ITurtleUpgrade> right) {
         var item = (TurtleItem) stack.getItem();
         return item.create(
             item.getComputerID(stack), item.getLabel(stack), item.getColour(stack),
@@ -223,7 +227,7 @@ public class UpgradeRecipeGenerator<T> {
         );
     }
 
-    private static ItemStack pocketWith(ItemStack stack, @Nullable IPocketUpgrade back) {
+    private static ItemStack pocketWith(ItemStack stack, @Nullable UpgradeData<IPocketUpgrade> back) {
         var item = (PocketComputerItem) stack.getItem();
         return item.create(
             item.getComputerID(stack), item.getLabel(stack), item.getColour(stack), back
@@ -272,7 +276,7 @@ public class UpgradeRecipeGenerator<T> {
                     recipes.add(turtle(
                         ingredient, // Right upgrade, recipe on left
                         Ingredient.of(turtleItem.create(-1, null, -1, null, null, 0, null)),
-                        turtleItem.create(-1, null, -1, null, turtle, 0, null)
+                        turtleItem.create(-1, null, -1, null, UpgradeData.ofDefault(turtle), 0, null)
                     ));
                 }
             }
@@ -283,7 +287,7 @@ public class UpgradeRecipeGenerator<T> {
                     recipes.add(pocket(
                         ingredient,
                         Ingredient.of(pocketItem.create(-1, null, -1, null)),
-                        pocketItem.create(-1, null, -1, pocket)
+                        pocketItem.create(-1, null, -1, UpgradeData.ofDefault(pocket))
                     ));
                 }
             }

projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/GenericPeripheral.java

@@ -12,19 +12,23 @@ import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IDynamicPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.shared.platform.RegistryWrappers;
+import net.minecraft.core.Direction;
 import net.minecraft.world.level.block.entity.BlockEntity;
 
 import javax.annotation.Nullable;
 import java.util.List;
 import java.util.Set;
 
-class GenericPeripheral implements IDynamicPeripheral {
+public final class GenericPeripheral implements IDynamicPeripheral {
+    private final BlockEntity tile;
+    private final Direction side;
+
     private final String type;
     private final Set<String> additionalTypes;
-    private final BlockEntity tile;
     private final List<SaturatedMethod> methods;
 
-    GenericPeripheral(BlockEntity tile, @Nullable String name, Set<String> additionalTypes, List<SaturatedMethod> methods) {
+    GenericPeripheral(BlockEntity tile, Direction side, @Nullable String name, Set<String> additionalTypes, List<SaturatedMethod> methods) {
+        this.side = side;
         var type = RegistryWrappers.BLOCK_ENTITY_TYPES.getKey(tile.getType());
         this.tile = tile;
         this.type = name != null ? name : type.toString();
@@ -32,6 +36,10 @@ class GenericPeripheral implements IDynamicPeripheral {
         this.methods = methods;
     }
 
+    public Direction side() {
+        return side;
+    }
+
     @Override
     public String[] getMethodNames() {
         var names = new String[methods.size()];
@@ -54,7 +62,6 @@ class GenericPeripheral implements IDynamicPeripheral {
         return additionalTypes;
     }
 
-    @Nullable
     @Override
     public Object getTarget() {
         return tile;

projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/GenericPeripheralBuilder.java

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.shared.peripheral.generic;
+
+import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.api.peripheral.PeripheralType;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.NamedMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
+import dan200.computercraft.shared.computer.core.ServerContext;
+import net.minecraft.core.Direction;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.world.level.block.entity.BlockEntity;
+
+import javax.annotation.Nullable;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A builder for a {@link GenericPeripheral}.
+ * <p>
+ * This handles building a list of {@linkplain SaturatedMethod methods} and computing the appropriate
+ * {@link PeripheralType} from the {@linkplain NamedMethod#genericType() methods' peripheral types}.
+ * <p>
+ * See the platform-specific peripheral providers for the usage of this.
+ */
+final class GenericPeripheralBuilder {
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
+
+    private @Nullable String name;
+    private final Set<String> additionalTypes = new HashSet<>(0);
+    private final ArrayList<SaturatedMethod> methods = new ArrayList<>();
+
+    GenericPeripheralBuilder(MinecraftServer server) {
+        peripheralMethods = ServerContext.get(server).peripheralMethods();
+    }
+
+    @Nullable
+    IPeripheral toPeripheral(BlockEntity blockEntity, Direction side) {
+        if (methods.isEmpty()) return null;
+
+        methods.trimToSize();
+        return new GenericPeripheral(blockEntity, side, name, additionalTypes, methods);
+    }
+
+    boolean addMethods(Object target) {
+        return peripheralMethods.forEachSelfMethod(target, (name, method, info) -> {
+            methods.add(new SaturatedMethod(target, name, method));
+
+            // If we have a peripheral type, use it. Always pick the smallest one, so it's consistent (assuming mods
+            // don't change).
+            var type = info == null ? null : info.genericType();
+            if (type != null && type.getPrimaryType() != null) {
+                var primaryType = type.getPrimaryType();
+                if (this.name == null || this.name.compareTo(primaryType) > 0) this.name = primaryType;
+            }
+            if (type != null) additionalTypes.addAll(type.getAdditionalTypes());
+        });
+    }
+}

projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java

@@ -9,18 +9,20 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.api.peripheral.IComputerAccess;
-import dan200.computercraft.core.asm.NamedMethod;
-import dan200.computercraft.core.asm.PeripheralMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
 
+/**
+ * A {@link PeripheralMethod} along with the method's target.
+ */
 final class SaturatedMethod {
     private final Object target;
     private final String name;
     private final PeripheralMethod method;
 
-    SaturatedMethod(Object target, NamedMethod<PeripheralMethod> method) {
+    SaturatedMethod(Object target, String name, PeripheralMethod method) {
         this.target = target;
-        name = method.getName();
-        this.method = method.getMethod();
+        this.name = name;
+        this.method = method;
     }
 
     MethodResult apply(ILuaContext context, IComputerAccess computer, IArguments args) throws LuaException {

projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/ModemState.java

@@ -11,7 +11,7 @@ import it.unimi.dsi.fastutil.ints.IntSet;
 import javax.annotation.Nullable;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-public class ModemState {
+public final class ModemState {
     private final @Nullable Runnable onChanged;
     private final AtomicBoolean changed = new AtomicBoolean(true);
 
@@ -69,4 +69,30 @@ public class ModemState {
             setOpen(false);
         }
     }
+
+    /**
+     * Copy this modem state, returning a new instance. The new instance will have the same set of open channels but no
+     * on-change listener.
+     *
+     * @return The new modem state.
+     */
+    public ModemState copy() {
+        return copy(null);
+    }
+
+    /**
+     * Copy this modem state, returning a new instance. The new instance will have the same set of open channels and a
+     * different on-change listener.
+     *
+     * @param onChanged The on-change listener.
+     * @return The new modem state.
+     */
+    public ModemState copy(@Nullable Runnable onChanged) {
+        synchronized (channels) {
+            var clone = onChanged == null ? new ModemState() : new ModemState(onChanged);
+            clone.channels.addAll(channels);
+            clone.open = open;
+            return clone;
+        }
+    }
 }

projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java

@@ -16,10 +16,12 @@ import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.NotAttachedException;
 import dan200.computercraft.api.peripheral.WorkMonitor;
 import dan200.computercraft.core.apis.PeripheralAPI;
-import dan200.computercraft.core.asm.PeripheralMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.core.util.LuaUtil;
+import dan200.computercraft.shared.computer.core.ServerContext;
 import dan200.computercraft.shared.peripheral.modem.ModemPeripheral;
 import dan200.computercraft.shared.peripheral.modem.ModemState;
+import net.minecraft.server.level.ServerLevel;
 import net.minecraft.world.level.Level;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -284,7 +286,8 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
 
     private void attachPeripheralImpl(IComputerAccess computer, ConcurrentMap<String, RemotePeripheralWrapper> peripherals, String periphName, IPeripheral peripheral) {
         if (!peripherals.containsKey(periphName) && !periphName.equals(getLocalPeripheral().getConnectedName())) {
-            var wrapper = new RemotePeripheralWrapper(modem, peripheral, computer, periphName);
+            var methods = ServerContext.get(((ServerLevel) getLevel()).getServer()).peripheralMethods().getSelfMethods(peripheral);
+            var wrapper = new RemotePeripheralWrapper(modem, peripheral, computer, periphName, methods);
             peripherals.put(periphName, wrapper);
             wrapper.attach();
         }
@@ -314,7 +317,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         private volatile boolean attached;
         private final Set<String> mounts = new HashSet<>();
 
-        RemotePeripheralWrapper(WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name) {
+        RemotePeripheralWrapper(WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name, Map<String, PeripheralMethod> methods) {
             this.element = element;
             this.peripheral = peripheral;
             this.computer = computer;
@@ -322,7 +325,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
 
             type = Objects.requireNonNull(peripheral.getType(), "Peripheral type cannot be null");
             additionalTypes = peripheral.getAdditionalTypes();
-            methodMap = PeripheralAPI.getMethods(peripheral);
+            methodMap = methods;
         }
 
         public void attach() {

projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wireless/WirelessModemBlockEntity.java

@@ -18,7 +18,7 @@ import net.minecraft.world.phys.Vec3;
 
 import javax.annotation.Nullable;
 
-public class WirelessModemBlockEntity extends BlockEntity {
+public final class WirelessModemBlockEntity extends BlockEntity {
     private static class Peripheral extends WirelessModemPeripheral {
         private final WirelessModemBlockEntity entity;
 
@@ -96,6 +96,10 @@ public class WirelessModemBlockEntity extends BlockEntity {
         }
     }
 
+    public ModemState getModemState() {
+        return modem.getModemState();
+    }
+
     @Nullable
     public IPeripheral getPeripheral(@Nullable Direction direction) {
         return direction == null || getDirection() == direction ? modem : null;

projects/common/src/main/java/dan200/computercraft/shared/peripheral/speaker/SpeakerPeripheral.java

@@ -190,7 +190,7 @@ public abstract class SpeakerPeripheral implements IPeripheral {
      * The speaker supports [all of Minecraft's noteblock instruments](https://minecraft.fandom.com/wiki/Note_Block#Instruments).
      * These are:
      * <p>
-     * {@code "harp"}, {@code "basedrum"}, {@code "snare"}, {@code "hat"}, {@code "bass"}, @code "flute"},
+     * {@code "harp"}, {@code "basedrum"}, {@code "snare"}, {@code "hat"}, {@code "bass"}, {@code "flute"},
      * {@code "bell"}, {@code "guitar"}, {@code "chime"}, {@code "xylophone"}, {@code "iron_xylophone"},
      * {@code "cow_bell"}, {@code "didgeridoo"}, {@code "bit"}, {@code "banjo"} and {@code "pling"}.
      *

projects/common/src/main/java/dan200/computercraft/shared/platform/FakePlayerConstants.java

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.shared.platform;
+
+import com.mojang.authlib.GameProfile;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.item.ItemStack;
+
+/**
+ * Shared constants for {@linkplain PlatformHelper#createFakePlayer(ServerLevel, GameProfile) fake player}
+ * implementations.
+ *
+ * @see net.minecraft.server.level.ServerPlayer
+ * @see net.minecraft.world.entity.player.Player
+ */
+final class FakePlayerConstants {
+    private FakePlayerConstants() {
+    }
+
+    /**
+     * The maximum distance this player can reach.
+     * <p>
+     * This is used in the override of {@link net.minecraft.world.entity.player.Player#mayUseItemAt(BlockPos, Direction, ItemStack)},
+     * to prevent the fake player reaching more than 2 blocks away.
+     */
+    static final double MAX_REACH = 2;
+}

projects/common/src/main/java/dan200/computercraft/shared/platform/PlatformHelper.java

@@ -68,6 +68,13 @@ public interface PlatformHelper extends dan200.computercraft.impl.PlatformHelper
         return (PlatformHelper) dan200.computercraft.impl.PlatformHelper.get();
     }
 
+    /**
+     * Check if we're running in a development environment.
+     *
+     * @return If we're running in a development environment.
+     */
+    boolean isDevelopmentEnvironment();
+
     /**
      * Create a new config builder.
      *

projects/common/src/main/java/dan200/computercraft/shared/pocket/apis/PocketAPI.java

@@ -7,6 +7,7 @@ package dan200.computercraft.shared.pocket.apis;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.LuaFunction;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.shared.pocket.core.PocketServerComputer;
 import net.minecraft.core.NonNullList;
@@ -14,6 +15,7 @@ import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.item.ItemStack;
 
 import javax.annotation.Nullable;
+import java.util.Objects;
 
 /**
  * Control the current pocket computer, adding or removing upgrades.
@@ -68,7 +70,7 @@ public class PocketAPI implements ILuaAPI {
         if (newUpgrade == null) return new Object[]{ false, "Cannot find a valid upgrade" };
 
         // Remove the current upgrade
-        if (previousUpgrade != null) storeItem(player, previousUpgrade.getCraftingItem().copy());
+        if (previousUpgrade != null) storeItem(player, previousUpgrade.getUpgradeItem());
 
         // Set the new upgrade
         computer.setUpgrade(newUpgrade);
@@ -93,7 +95,7 @@ public class PocketAPI implements ILuaAPI {
 
         computer.setUpgrade(null);
 
-        storeItem(player, previousUpgrade.getCraftingItem().copy());
+        storeItem(player, previousUpgrade.getUpgradeItem());
 
         return new Object[]{ true };
     }
@@ -105,13 +107,13 @@ public class PocketAPI implements ILuaAPI {
         }
     }
 
-    private static @Nullable IPocketUpgrade findUpgrade(NonNullList<ItemStack> inv, int start, @Nullable IPocketUpgrade previous) {
+    private static @Nullable UpgradeData<IPocketUpgrade> findUpgrade(NonNullList<ItemStack> inv, int start, @Nullable UpgradeData<IPocketUpgrade> previous) {
         for (var i = 0; i < inv.size(); i++) {
             var invStack = inv.get((i + start) % inv.size());
             if (!invStack.isEmpty()) {
                 var newUpgrade = PocketUpgrades.instance().get(invStack);
 
-                if (newUpgrade != null && newUpgrade != previous) {
+                if (newUpgrade != null && !Objects.equals(newUpgrade, previous)) {
                     // Consume an item from this stack and exit the loop
                     invStack = invStack.copy();
                     invStack.shrink(1);

projects/common/src/main/java/dan200/computercraft/shared/pocket/core/PocketServerComputer.java

@@ -7,6 +7,7 @@ package dan200.computercraft.shared.pocket.core;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.pocket.IPocketAccess;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.shared.common.IColouredItem;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
@@ -104,12 +105,13 @@ public class PocketServerComputer extends ServerComputer implements IPocketAcces
     }
 
     @Override
+    @Deprecated(forRemoval = true)
     public Map<ResourceLocation, IPeripheral> getUpgrades() {
         return upgrade == null ? Collections.emptyMap() : Collections.singletonMap(upgrade.getUpgradeID(), getPeripheral(ComputerSide.BACK));
     }
 
-    public @Nullable IPocketUpgrade getUpgrade() {
-        return upgrade;
+    public @Nullable UpgradeData<IPocketUpgrade> getUpgrade() {
+        return upgrade == null ? null : UpgradeData.of(upgrade, getUpgradeNBTData());
     }
 
     /**
@@ -119,13 +121,11 @@ public class PocketServerComputer extends ServerComputer implements IPocketAcces
      *
      * @param upgrade The new upgrade to set it to, may be {@code null}.
      */
-    public void setUpgrade(@Nullable IPocketUpgrade upgrade) {
-        if (this.upgrade == upgrade) return;
-
+    public void setUpgrade(@Nullable UpgradeData<IPocketUpgrade> upgrade) {
         synchronized (this) {
             PocketComputerItem.setUpgrade(stack, upgrade);
             updateUpgradeNBTData();
-            this.upgrade = upgrade;
+            this.upgrade = upgrade == null ? null : upgrade.upgrade();
             invalidatePeripheral();
         }
     }

projects/common/src/main/java/dan200/computercraft/shared/pocket/items/PocketComputerItem.java

@@ -10,6 +10,7 @@ import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.filesystem.Mount;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.shared.ModRegistry;
@@ -23,6 +24,7 @@ import dan200.computercraft.shared.pocket.apis.PocketAPI;
 import dan200.computercraft.shared.pocket.core.PocketServerComputer;
 import dan200.computercraft.shared.pocket.inventory.PocketComputerMenuProvider;
 import dan200.computercraft.shared.util.IDAssigner;
+import dan200.computercraft.shared.util.NBTUtil;
 import net.minecraft.ChatFormatting;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.chat.Component;
@@ -58,7 +60,7 @@ public class PocketComputerItem extends Item implements IComputerItem, IMedia, I
         this.family = family;
     }
 
-    public static ItemStack create(int id, @Nullable String label, int colour, ComputerFamily family, @Nullable IPocketUpgrade upgrade) {
+    public static ItemStack create(int id, @Nullable String label, int colour, ComputerFamily family, @Nullable UpgradeData<IPocketUpgrade> upgrade) {
         return switch (family) {
             case NORMAL -> ModRegistry.Items.POCKET_COMPUTER_NORMAL.get().create(id, label, colour, upgrade);
             case ADVANCED -> ModRegistry.Items.POCKET_COMPUTER_ADVANCED.get().create(id, label, colour, upgrade);
@@ -66,11 +68,14 @@ public class PocketComputerItem extends Item implements IComputerItem, IMedia, I
         };
     }
 
-    public ItemStack create(int id, @Nullable String label, int colour, @Nullable IPocketUpgrade upgrade) {
+    public ItemStack create(int id, @Nullable String label, int colour, @Nullable UpgradeData<IPocketUpgrade> upgrade) {
         var result = new ItemStack(this);
         if (id >= 0) result.getOrCreateTag().putInt(NBT_ID, id);
         if (label != null) result.setHoverName(Component.literal(label));
-        if (upgrade != null) result.getOrCreateTag().putString(NBT_UPGRADE, upgrade.getUpgradeID().toString());
+        if (upgrade != null) {
+            result.getOrCreateTag().putString(NBT_UPGRADE, upgrade.upgrade().getUpgradeID().toString());
+            if (!upgrade.data().isEmpty()) result.getOrCreateTag().put(NBT_UPGRADE_INFO, upgrade.data().copy());
+        }
         if (colour != -1) result.getOrCreateTag().putInt(NBT_COLOUR, colour);
         return result;
     }
@@ -207,7 +212,9 @@ public class PocketComputerItem extends Item implements IComputerItem, IMedia, I
             setInstanceID(stack, computer.register());
             setSessionID(stack, registry.getSessionID());
 
-            computer.updateValues(entity, stack, getUpgrade(stack));
+            var upgrade = getUpgrade(stack);
+
+            computer.updateValues(entity, stack, upgrade);
             computer.addAPI(new PocketAPI(computer));
 
             // Only turn on when initially creating the computer, rather than each tick.
@@ -244,7 +251,7 @@ public class PocketComputerItem extends Item implements IComputerItem, IMedia, I
     public ItemStack withFamily(ItemStack stack, ComputerFamily family) {
         return create(
             getComputerID(stack), getLabel(stack), getColour(stack),
-            family, getUpgrade(stack)
+            family, getUpgradeWithData(stack)
         );
     }
 
@@ -294,20 +301,27 @@ public class PocketComputerItem extends Item implements IComputerItem, IMedia, I
 
     public static @Nullable IPocketUpgrade getUpgrade(ItemStack stack) {
         var compound = stack.getTag();
-        return compound != null && compound.contains(NBT_UPGRADE)
-            ? PocketUpgrades.instance().get(compound.getString(NBT_UPGRADE)) : null;
+        if (compound == null || !compound.contains(NBT_UPGRADE)) return null;
+        return PocketUpgrades.instance().get(compound.getString(NBT_UPGRADE));
     }
 
-    public static void setUpgrade(ItemStack stack, @Nullable IPocketUpgrade upgrade) {
+    public static @Nullable UpgradeData<IPocketUpgrade> getUpgradeWithData(ItemStack stack) {
+        var compound = stack.getTag();
+        if (compound == null || !compound.contains(NBT_UPGRADE)) return null;
+        var upgrade = PocketUpgrades.instance().get(compound.getString(NBT_UPGRADE));
+        return upgrade == null ? null : UpgradeData.of(upgrade, NBTUtil.getCompoundOrEmpty(compound, NBT_UPGRADE_INFO));
+    }
+
+    public static void setUpgrade(ItemStack stack, @Nullable UpgradeData<IPocketUpgrade> upgrade) {
         var compound = stack.getOrCreateTag();
 
         if (upgrade == null) {
             compound.remove(NBT_UPGRADE);
+            compound.remove(NBT_UPGRADE_INFO);
         } else {
-            compound.putString(NBT_UPGRADE, upgrade.getUpgradeID().toString());
+            compound.putString(NBT_UPGRADE, upgrade.upgrade().getUpgradeID().toString());
+            compound.put(NBT_UPGRADE_INFO, upgrade.data().copy());
         }
-
-        compound.remove(NBT_UPGRADE_INFO);
     }
 
     public static CompoundTag getUpgradeInfo(ItemStack stack) {

projects/common/src/main/java/dan200/computercraft/shared/pocket/recipes/PocketComputerUpgradeRecipe.java

@@ -5,6 +5,7 @@
 package dan200.computercraft.shared.pocket.recipes;
 
 import dan200.computercraft.api.pocket.IPocketUpgrade;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.PocketUpgrades;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.pocket.items.PocketComputerItem;
@@ -62,7 +63,7 @@ public final class PocketComputerUpgradeRecipe extends CustomRecipe {
         if (PocketComputerItem.getUpgrade(computer) != null) return ItemStack.EMPTY;
 
         // Check for upgrades around the item
-        IPocketUpgrade upgrade = null;
+        UpgradeData<IPocketUpgrade> upgrade = null;
         for (var y = 0; y < inventory.getHeight(); y++) {
             for (var x = 0; x < inventory.getWidth(); x++) {
                 var item = inventory.getItem(x + y * inventory.getWidth());

projects/common/src/main/java/dan200/computercraft/shared/turtle/blocks/TurtleBlock.java

@@ -5,7 +5,9 @@
 package dan200.computercraft.shared.turtle.blocks;
 
 import dan200.computercraft.annotations.ForgeOverride;
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.shared.computer.blocks.AbstractComputerBlock;
 import dan200.computercraft.shared.computer.blocks.AbstractComputerBlockEntity;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
@@ -128,7 +130,7 @@ public class TurtleBlock extends AbstractComputerBlock<TurtleBlockEntity> implem
             if (stack.getItem() instanceof TurtleItem item) {
                 // Set Upgrades
                 for (var side : TurtleSide.values()) {
-                    turtle.getAccess().setUpgrade(side, item.getUpgrade(stack, side));
+                    turtle.getAccess().setUpgradeWithData(side, item.getUpgradeWithData(stack, side));
                 }
 
                 turtle.getAccess().setFuelLevel(item.getFuelLevel(stack));
@@ -161,11 +163,16 @@ public class TurtleBlock extends AbstractComputerBlock<TurtleBlockEntity> implem
         var access = turtle.getAccess();
         return TurtleItem.create(
             turtle.getComputerID(), turtle.getLabel(), access.getColour(), turtle.getFamily(),
-            access.getUpgrade(TurtleSide.LEFT), access.getUpgrade(TurtleSide.RIGHT),
+            withPersistedData(access.getUpgradeWithData(TurtleSide.LEFT)),
+            withPersistedData(access.getUpgradeWithData(TurtleSide.RIGHT)),
             access.getFuelLevel(), turtle.getOverlay()
         );
     }
 
+    private static @Nullable UpgradeData<ITurtleUpgrade> withPersistedData(@Nullable UpgradeData<ITurtleUpgrade> upgrade) {
+        return upgrade == null ? null : UpgradeData.of(upgrade.upgrade(), upgrade.upgrade().getPersistedData(upgrade.data()));
+    }
+
     @Override
     @Nullable
     public <U extends BlockEntity> BlockEntityTicker<U> getTicker(Level level, BlockState state, BlockEntityType<U> type) {

projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java

@@ -13,6 +13,7 @@ import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleAnimation;
 import dan200.computercraft.api.turtle.TurtleCommand;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.util.Colour;
 import dan200.computercraft.impl.TurtleUpgrades;
@@ -141,17 +142,16 @@ public class TurtleBrain implements TurtleAccessInternal {
         overlay = nbt.contains(NBT_OVERLAY) ? new ResourceLocation(nbt.getString(NBT_OVERLAY)) : null;
 
         // Read upgrades
-        setUpgradeDirect(TurtleSide.LEFT, nbt.contains(NBT_LEFT_UPGRADE) ? TurtleUpgrades.instance().get(nbt.getString(NBT_LEFT_UPGRADE)) : null);
-        setUpgradeDirect(TurtleSide.RIGHT, nbt.contains(NBT_RIGHT_UPGRADE) ? TurtleUpgrades.instance().get(nbt.getString(NBT_RIGHT_UPGRADE)) : null);
+        setUpgradeDirect(TurtleSide.LEFT, readUpgrade(nbt, NBT_LEFT_UPGRADE, NBT_LEFT_UPGRADE_DATA));
+        setUpgradeDirect(TurtleSide.RIGHT, readUpgrade(nbt, NBT_RIGHT_UPGRADE, NBT_RIGHT_UPGRADE_DATA));
+    }
 
-        // NBT
-        upgradeNBTData.clear();
-        if (nbt.contains(NBT_LEFT_UPGRADE_DATA)) {
-            upgradeNBTData.put(TurtleSide.LEFT, nbt.getCompound(NBT_LEFT_UPGRADE_DATA).copy());
-        }
-        if (nbt.contains(NBT_RIGHT_UPGRADE_DATA)) {
-            upgradeNBTData.put(TurtleSide.RIGHT, nbt.getCompound(NBT_RIGHT_UPGRADE_DATA).copy());
-        }
+    private @Nullable UpgradeData<ITurtleUpgrade> readUpgrade(CompoundTag tag, String upgradeKey, String dataKey) {
+        if (!tag.contains(upgradeKey)) return null;
+        var upgrade = TurtleUpgrades.instance().get(tag.getString(upgradeKey));
+        if (upgrade == null) return null;
+
+        return UpgradeData.of(upgrade, tag.getCompound(dataKey));
     }
 
     private void writeCommon(CompoundTag nbt) {
@@ -516,7 +516,7 @@ public class TurtleBrain implements TurtleAccessInternal {
     }
 
     @Override
-    public void setUpgrade(TurtleSide side, @Nullable ITurtleUpgrade upgrade) {
+    public void setUpgradeWithData(TurtleSide side, @Nullable UpgradeData<ITurtleUpgrade> upgrade) {
         if (!setUpgradeDirect(side, upgrade) || owner.getLevel() == null) return;
 
         // This is a separate function to avoid updating the block when reading the NBT. We don't need to do this as
@@ -529,19 +529,18 @@ public class TurtleBrain implements TurtleAccessInternal {
         owner.updateInputsImmediately();
     }
 
-    private boolean setUpgradeDirect(TurtleSide side, @Nullable ITurtleUpgrade upgrade) {
+    private boolean setUpgradeDirect(TurtleSide side, @Nullable UpgradeData<ITurtleUpgrade> upgrade) {
         // Remove old upgrade
-        if (upgrades.containsKey(side)) {
-            if (upgrades.get(side) == upgrade) return false;
-            upgrades.remove(side);
-        } else {
-            if (upgrade == null) return false;
-        }
-
-        upgradeNBTData.remove(side);
+        var oldUpgrade = upgrades.remove(side);
+        if (oldUpgrade == null && upgrade == null) return false;
 
         // Set new upgrade
-        if (upgrade != null) upgrades.put(side, upgrade);
+        if (upgrade == null) {
+            upgradeNBTData.remove(side);
+        } else {
+            upgrades.put(side, upgrade.upgrade());
+            upgradeNBTData.put(side, upgrade.data().copy());
+        }
 
         // Notify clients and create peripherals
         if (owner.getLevel() != null && !owner.getLevel().isClientSide) {
@@ -595,7 +594,7 @@ public class TurtleBrain implements TurtleAccessInternal {
 
     public float getToolRenderAngle(TurtleSide side, float f) {
         return (side == TurtleSide.LEFT && animation == TurtleAnimation.SWING_LEFT_TOOL) ||
-            (side == TurtleSide.RIGHT && animation == TurtleAnimation.SWING_RIGHT_TOOL)
+               (side == TurtleSide.RIGHT && animation == TurtleAnimation.SWING_RIGHT_TOOL)
             ? 45.0f * (float) Math.sin(getAnimationFraction(f) * Math.PI)
             : 0.0f;
     }

projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleEquipCommand.java

@@ -5,6 +5,7 @@
 package dan200.computercraft.shared.turtle.core;
 
 import dan200.computercraft.api.turtle.*;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.turtle.TurtleUtil;
 
@@ -18,10 +19,10 @@ public class TurtleEquipCommand implements TurtleCommand {
     @Override
     public TurtleCommandResult execute(ITurtleAccess turtle) {
         // Determine the upgrade to replace
-        var oldUpgrade = turtle.getUpgrade(side);
+        var oldUpgrade = turtle.getUpgradeWithData(side);
 
         // Determine the upgrade to equipLeft
-        ITurtleUpgrade newUpgrade;
+        UpgradeData<ITurtleUpgrade> newUpgrade;
         var selectedStack = turtle.getInventory().getItem(turtle.getSelectedSlot());
         if (!selectedStack.isEmpty()) {
             newUpgrade = TurtleUpgrades.instance().get(selectedStack);
@@ -32,8 +33,8 @@ public class TurtleEquipCommand implements TurtleCommand {
 
         // Do the swapping:
         if (newUpgrade != null) turtle.getInventory().removeItem(turtle.getSelectedSlot(), 1);
-        if (oldUpgrade != null) TurtleUtil.storeItemOrDrop(turtle, oldUpgrade.getCraftingItem().copy());
-        turtle.setUpgrade(side, newUpgrade);
+        if (oldUpgrade != null) TurtleUtil.storeItemOrDrop(turtle, oldUpgrade.getUpgradeItem());
+        turtle.setUpgradeWithData(side, newUpgrade);
 
         // Animate
         if (newUpgrade != null || oldUpgrade != null) {

projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/TurtleMenu.java

@@ -4,6 +4,7 @@
 
 package dan200.computercraft.shared.turtle.inventory;
 
+import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.core.ServerComputer;
@@ -29,12 +30,13 @@ public final class TurtleMenu extends AbstractComputerMenu {
     public static final int PLAYER_START_Y = 134;
     public static final int TURTLE_START_X = SIDEBAR_WIDTH + 175;
     public static final int PLAYER_START_X = SIDEBAR_WIDTH + BORDER;
+    public static final int UPGRADE_START_X = SIDEBAR_WIDTH + 254;
 
     private final ContainerData data;
 
     private TurtleMenu(
         int id, Predicate<Player> canUse, ComputerFamily family, @Nullable ServerComputer computer, @Nullable ComputerContainerData menuData,
-        Inventory playerInventory, Container inventory, ContainerData data
+        Inventory playerInventory, Container inventory, Container turtleUpgrades, ContainerData data
     ) {
         super(ModRegistry.Menus.TURTLE.get(), id, canUse, family, computer, menuData);
         this.data = data;
@@ -58,19 +60,24 @@ public final class TurtleMenu extends AbstractComputerMenu {
         for (var x = 0; x < 9; x++) {
             addSlot(new Slot(playerInventory, x, PLAYER_START_X + x * 18, PLAYER_START_Y + 3 * 18 + 5));
         }
+
+        // Turtle upgrades
+        addSlot(new UpgradeSlot(turtleUpgrades, TurtleSide.LEFT, 0, UPGRADE_START_X, PLAYER_START_Y + 1));
+        addSlot(new UpgradeSlot(turtleUpgrades, TurtleSide.RIGHT, 1, UPGRADE_START_X, PLAYER_START_Y + 1 + 18));
     }
 
     public static TurtleMenu ofBrain(int id, Inventory player, TurtleBrain turtle) {
         return new TurtleMenu(
             // Laziness in turtle.getOwner() is important here!
             id, p -> turtle.getOwner().stillValid(p), turtle.getFamily(), turtle.getOwner().createServerComputer(), null,
-            player, turtle.getInventory(), (SingleContainerData) turtle::getSelectedSlot
+            player, turtle.getInventory(), new UpgradeContainer(turtle), (SingleContainerData) turtle::getSelectedSlot
         );
     }
 
     public static TurtleMenu ofMenuData(int id, Inventory player, ComputerContainerData data) {
         return new TurtleMenu(
-            id, x -> true, data.family(), null, data, player, new SimpleContainer(TurtleBlockEntity.INVENTORY_SIZE), new SimpleContainerData(1)
+            id, x -> true, data.family(), null, data,
+            player, new SimpleContainer(TurtleBlockEntity.INVENTORY_SIZE), new SimpleContainer(2), new SimpleContainerData(1)
         );
     }
 

projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeContainer.java

@@ -0,0 +1,117 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.shared.turtle.inventory;
+
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
+import dan200.computercraft.impl.TurtleUpgrades;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+
+import javax.annotation.Nullable;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * A fake {@link Container} which exposes the {@linkplain ITurtleAccess#getUpgrade(TurtleSide) upgrades} a turtle has.
+ *
+ * @see TurtleMenu
+ * @see UpgradeSlot
+ */
+class UpgradeContainer implements Container {
+    private static final int SIZE = 2;
+
+    private final ITurtleAccess turtle;
+
+    private final List<UpgradeData<ITurtleUpgrade>> lastUpgrade = Arrays.asList(null, null);
+    private final NonNullList<ItemStack> lastStack = NonNullList.withSize(2, ItemStack.EMPTY);
+
+    UpgradeContainer(ITurtleAccess turtle) {
+        this.turtle = turtle;
+    }
+
+    private TurtleSide getSide(int slot) {
+        return switch (slot) {
+            case 0 -> TurtleSide.LEFT;
+            case 1 -> TurtleSide.RIGHT;
+            default -> throw new IllegalArgumentException("Invalid slot " + slot);
+        };
+    }
+
+    @Override
+    public ItemStack getItem(int slot) {
+        var side = getSide(slot);
+        var upgrade = turtle.getUpgradeWithData(side);
+        if (upgrade == null) return ItemStack.EMPTY;
+
+        // We don't want to return getUpgradeItem directly here, as we'd end up recreating the stack each tick. To
+        // avoid that, we maintain a simple cache.
+        if (upgrade.equals(lastUpgrade.get(slot))) return lastStack.get(slot);
+
+        return setUpgradeStack(slot, upgrade);
+    }
+
+    private ItemStack setUpgradeStack(int slot, @Nullable UpgradeData<ITurtleUpgrade> upgrade) {
+        var stack = upgrade == null ? ItemStack.EMPTY : upgrade.getUpgradeItem();
+        lastUpgrade.set(slot, upgrade);
+        lastStack.set(slot, stack);
+        return stack;
+    }
+
+    @Override
+    public void setItem(int slot, ItemStack itemStack) {
+        var upgrade = TurtleUpgrades.instance().get(itemStack);
+        turtle.setUpgradeWithData(getSide(slot), upgrade);
+        setUpgradeStack(slot, upgrade);
+    }
+
+    @Override
+    public int getContainerSize() {
+        return SIZE;
+    }
+
+    @Override
+    public int getMaxStackSize() {
+        return 1;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        for (var i = 0; i < SIZE; i++) {
+            if (!getItem(i).isEmpty()) return false;
+        }
+        return true;
+    }
+
+    @Override
+    public ItemStack removeItem(int slot, int count) {
+        return count <= 0 ? ItemStack.EMPTY : removeItemNoUpdate(slot);
+    }
+
+    @Override
+    public ItemStack removeItemNoUpdate(int slot) {
+        var current = getItem(slot);
+        setItem(slot, ItemStack.EMPTY);
+        return current;
+    }
+
+    @Override
+    public void setChanged() {
+    }
+
+    @Override
+    public boolean stillValid(Player player) {
+        return true;
+    }
+
+    @Override
+    public void clearContent() {
+        for (var i = 0; i < SIZE; i++) setItem(i, ItemStack.EMPTY);
+    }
+}

projects/common/src/main/java/dan200/computercraft/shared/turtle/inventory/UpgradeSlot.java

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.shared.turtle.inventory;
+
+import com.mojang.datafixers.util.Pair;
+import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.impl.TurtleUpgrades;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+
+import javax.annotation.Nullable;
+
+/**
+ * A slot in the turtle UI which holds the turtle's current upgrade.
+ *
+ * @see TurtleMenu
+ */
+public class UpgradeSlot extends Slot {
+    public static final ResourceLocation LEFT_UPGRADE = new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/turtle_upgrade_left");
+    public static final ResourceLocation RIGHT_UPGRADE = new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/turtle_upgrade_right");
+
+    private final TurtleSide side;
+
+    public UpgradeSlot(Container container, TurtleSide side, int slot, int xPos, int yPos) {
+        super(container, slot, xPos, yPos);
+        this.side = side;
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack stack) {
+        return TurtleUpgrades.instance().get(stack) != null;
+    }
+
+    @Override
+    public int getMaxStackSize() {
+        return 1;
+    }
+
+    @Nullable
+    @Override
+    public Pair<ResourceLocation, ResourceLocation> getNoItemIcon() {
+        return Pair.of(InventoryMenu.BLOCK_ATLAS, side == TurtleSide.LEFT ? LEFT_UPGRADE : RIGHT_UPGRADE);
+    }
+}

projects/common/src/main/java/dan200/computercraft/shared/turtle/items/TurtleItem.java

@@ -8,12 +8,14 @@ import dan200.computercraft.annotations.ForgeOverride;
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.common.IColouredItem;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.items.AbstractComputerItem;
 import dan200.computercraft.shared.turtle.blocks.TurtleBlock;
+import dan200.computercraft.shared.util.NBTUtil;
 import net.minecraft.core.cauldron.CauldronInteraction;
 import net.minecraft.network.chat.Component;
 import net.minecraft.resources.ResourceLocation;
@@ -32,7 +34,7 @@ public class TurtleItem extends AbstractComputerItem implements IColouredItem {
 
     public static ItemStack create(
         int id, @Nullable String label, int colour, ComputerFamily family,
-        @Nullable ITurtleUpgrade leftUpgrade, @Nullable ITurtleUpgrade rightUpgrade,
+        @Nullable UpgradeData<ITurtleUpgrade> leftUpgrade, @Nullable UpgradeData<ITurtleUpgrade> rightUpgrade,
         int fuelLevel, @Nullable ResourceLocation overlay
     ) {
         return switch (family) {
@@ -46,7 +48,7 @@ public class TurtleItem extends AbstractComputerItem implements IColouredItem {
 
     public ItemStack create(
         int id, @Nullable String label, int colour,
-        @Nullable ITurtleUpgrade leftUpgrade, @Nullable ITurtleUpgrade rightUpgrade,
+        @Nullable UpgradeData<ITurtleUpgrade> leftUpgrade, @Nullable UpgradeData<ITurtleUpgrade> rightUpgrade,
         int fuelLevel, @Nullable ResourceLocation overlay
     ) {
         // Build the stack
@@ -58,11 +60,15 @@ public class TurtleItem extends AbstractComputerItem implements IColouredItem {
         if (overlay != null) stack.getOrCreateTag().putString(NBT_OVERLAY, overlay.toString());
 
         if (leftUpgrade != null) {
-            stack.getOrCreateTag().putString(NBT_LEFT_UPGRADE, leftUpgrade.getUpgradeID().toString());
+            var tag = stack.getOrCreateTag();
+            tag.putString(NBT_LEFT_UPGRADE, leftUpgrade.upgrade().getUpgradeID().toString());
+            if (!leftUpgrade.data().isEmpty()) tag.put(NBT_LEFT_UPGRADE_DATA, leftUpgrade.data().copy());
         }
 
         if (rightUpgrade != null) {
-            stack.getOrCreateTag().putString(NBT_RIGHT_UPGRADE, rightUpgrade.getUpgradeID().toString());
+            var tag = stack.getOrCreateTag();
+            tag.putString(NBT_RIGHT_UPGRADE, rightUpgrade.upgrade().getUpgradeID().toString());
+            if (!rightUpgrade.data().isEmpty()) tag.put(NBT_RIGHT_UPGRADE_DATA, rightUpgrade.data().copy());
         }
 
         return stack;
@@ -117,7 +123,7 @@ public class TurtleItem extends AbstractComputerItem implements IColouredItem {
         return create(
             getComputerID(stack), getLabel(stack),
             getColour(stack), family,
-            getUpgrade(stack, TurtleSide.LEFT), getUpgrade(stack, TurtleSide.RIGHT),
+            getUpgradeWithData(stack, TurtleSide.LEFT), getUpgradeWithData(stack, TurtleSide.RIGHT),
             getFuelLevel(stack), getOverlay(stack)
         );
     }
@@ -127,7 +133,20 @@ public class TurtleItem extends AbstractComputerItem implements IColouredItem {
         if (tag == null) return null;
 
         var key = side == TurtleSide.LEFT ? NBT_LEFT_UPGRADE : NBT_RIGHT_UPGRADE;
-        return tag.contains(key) ? TurtleUpgrades.instance().get(tag.getString(key)) : null;
+        if (!tag.contains(key)) return null;
+        return TurtleUpgrades.instance().get(tag.getString(key));
+    }
+
+    public @Nullable UpgradeData<ITurtleUpgrade> getUpgradeWithData(ItemStack stack, TurtleSide side) {
+        var tag = stack.getTag();
+        if (tag == null) return null;
+
+        var key = side == TurtleSide.LEFT ? NBT_LEFT_UPGRADE : NBT_RIGHT_UPGRADE;
+        if (!tag.contains(key)) return null;
+        var upgrade = TurtleUpgrades.instance().get(tag.getString(key));
+        if (upgrade == null) return null;
+        var dataKey = side == TurtleSide.LEFT ? NBT_LEFT_UPGRADE_DATA : NBT_RIGHT_UPGRADE_DATA;
+        return UpgradeData.of(upgrade, NBTUtil.getCompoundOrEmpty(tag, dataKey));
     }
 
     public @Nullable ResourceLocation getOverlay(ItemStack stack) {

projects/common/src/main/java/dan200/computercraft/shared/turtle/recipes/TurtleOverlayRecipe.java

@@ -38,8 +38,8 @@ public class TurtleOverlayRecipe extends ShapelessRecipe {
             turtle.getComputerID(stack),
             turtle.getLabel(stack),
             turtle.getColour(stack),
-            turtle.getUpgrade(stack, TurtleSide.LEFT),
-            turtle.getUpgrade(stack, TurtleSide.RIGHT),
+            turtle.getUpgradeWithData(stack, TurtleSide.LEFT),
+            turtle.getUpgradeWithData(stack, TurtleSide.RIGHT),
             turtle.getFuelLevel(stack),
             overlay
         );

projects/common/src/main/java/dan200/computercraft/shared/turtle/recipes/TurtleUpgradeRecipe.java

@@ -6,6 +6,7 @@ package dan200.computercraft.shared.turtle.recipes;
 
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.turtle.items.TurtleItem;
@@ -104,9 +105,10 @@ public final class TurtleUpgradeRecipe extends CustomRecipe {
         // At this point we have a turtle + 1 or 2 items
         // Get the turtle we already have
         var itemTurtle = (TurtleItem) turtle.getItem();
-        var upgrades = new ITurtleUpgrade[]{
-            itemTurtle.getUpgrade(turtle, TurtleSide.LEFT),
-            itemTurtle.getUpgrade(turtle, TurtleSide.RIGHT),
+        @SuppressWarnings({ "unchecked", "rawtypes" })
+        UpgradeData<ITurtleUpgrade>[] upgrades = new UpgradeData[]{
+            itemTurtle.getUpgradeWithData(turtle, TurtleSide.LEFT),
+            itemTurtle.getUpgradeWithData(turtle, TurtleSide.RIGHT),
         };
 
         // Get the upgrades for the new items

projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleModem.java

@@ -9,6 +9,7 @@ import dan200.computercraft.api.turtle.*;
 import dan200.computercraft.shared.peripheral.modem.ModemState;
 import dan200.computercraft.shared.peripheral.modem.wireless.WirelessModemPeripheral;
 import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.level.Level;
@@ -77,4 +78,9 @@ public class TurtleModem extends AbstractTurtleUpgrade {
             }
         }
     }
+
+    @Override
+    public CompoundTag getPersistedData(CompoundTag upgradeData) {
+        return new CompoundTag();
+    }
 }

projects/common/src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java

@@ -14,6 +14,7 @@ import dan200.computercraft.shared.util.DropConsumer;
 import dan200.computercraft.shared.util.WorldUtil;
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.tags.TagKey;
@@ -59,7 +60,7 @@ public class TurtleTool extends AbstractTurtleUpgrade {
 
         // Check we've not got anything vaguely interesting on the item. We allow other mods to add their
         // own NBT, with the understanding such details will be lost to the mist of time.
-        if (stack.isDamaged() || stack.isEnchanted() || stack.hasCustomHoverName()) return false;
+        if (stack.isDamaged() || stack.isEnchanted()) return false;
         if (tag.contains("AttributeModifiers", TAG_LIST) && !tag.getList("AttributeModifiers", TAG_COMPOUND).isEmpty()) {
             return false;
         }
@@ -67,6 +68,21 @@ public class TurtleTool extends AbstractTurtleUpgrade {
         return true;
     }
 
+    @Override
+    public CompoundTag getUpgradeData(ItemStack stack) {
+        // Just use the current item's tag.
+        var itemTag = stack.getTag();
+        return itemTag == null ? new CompoundTag() : itemTag;
+    }
+
+    @Override
+    public ItemStack getUpgradeItem(CompoundTag upgradeData) {
+        // Copy upgrade data back to the item.
+        var item = super.getUpgradeItem(upgradeData);
+        if (!upgradeData.isEmpty()) item.setTag(upgradeData);
+        return item;
+    }
+
     @Override
     public TurtleCommandResult useTool(ITurtleAccess turtle, TurtleSide side, TurtleVerb verb, Direction direction) {
         return switch (verb) {
@@ -177,7 +193,8 @@ public class TurtleTool extends AbstractTurtleUpgrade {
     }
 
     private static boolean isTriviallyBreakable(BlockGetter reader, BlockPos pos, BlockState state) {
-        return state.is(ComputerCraftTags.Blocks.TURTLE_ALWAYS_BREAKABLE)
+        return
+            state.is(ComputerCraftTags.Blocks.TURTLE_ALWAYS_BREAKABLE)
             // Allow breaking any "instabreak" block.
             || state.getDestroySpeed(reader, pos) == 0;
     }

projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java

@@ -7,6 +7,7 @@ package dan200.computercraft.shared.util;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.io.BaseEncoding;
 import dan200.computercraft.core.util.Nullability;
+import dan200.computercraft.shared.platform.PlatformHelper;
 import net.minecraft.nbt.*;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -19,6 +20,7 @@ import java.io.OutputStream;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -27,9 +29,42 @@ public final class NBTUtil {
     @VisibleForTesting
     static final BaseEncoding ENCODING = BaseEncoding.base16().lowerCase();
 
+    private static final CompoundTag EMPTY_TAG;
+
+    static {
+        // If in a development environment, create a magic immutable compound tag.
+        // We avoid doing this in prod, as I fear it might mess up the JIT inlining things.
+        if (PlatformHelper.get().isDevelopmentEnvironment()) {
+            try {
+                var ctor = CompoundTag.class.getDeclaredConstructor(Map.class);
+                ctor.setAccessible(true);
+                EMPTY_TAG = ctor.newInstance(Collections.emptyMap());
+            } catch (ReflectiveOperationException e) {
+                throw new RuntimeException(e);
+            }
+        } else {
+            EMPTY_TAG = new CompoundTag();
+        }
+    }
+
     private NBTUtil() {
     }
 
+    /**
+     * Get a singleton empty {@link CompoundTag}. This tag should never be modified.
+     *
+     * @return The empty compound tag.
+     */
+    public static CompoundTag emptyTag() {
+        if (EMPTY_TAG.size() != 0) LOG.error("The empty tag has been modified.");
+        return EMPTY_TAG;
+    }
+
+    public static CompoundTag getCompoundOrEmpty(CompoundTag tag, String key) {
+        var childTag = tag.get(key);
+        return childTag != null && childTag.getId() == Tag.TAG_COMPOUND ? (CompoundTag) childTag : emptyTag();
+    }
+
     private static @Nullable Tag toNBTTag(@Nullable Object object) {
         if (object == null) return null;
         if (object instanceof Boolean) return ByteTag.valueOf((byte) ((boolean) (Boolean) object ? 1 : 0));

projects/common/src/main/resources/assets/computercraft/lang/ru_ru.json

@@ -115,5 +115,67 @@
     "upgrade.minecraft.diamond_pickaxe.adjective": "Добывающая",
     "upgrade.minecraft.diamond_shovel.adjective": "Копающая",
     "upgrade.minecraft.diamond_sword.adjective": "Боевая",
-    "gui.computercraft.pocket_computer_overlay": "Карманный компьютер открыт. Чтобы закрыть, нажми ESC."
+    "gui.computercraft.pocket_computer_overlay": "Карманный компьютер открыт. Чтобы закрыть, нажми ESC.",
+    "gui.computercraft.config.command_require_creative.tooltip": "Требовать творческий режим и права оператора для взаимодействия с\nкомандными компьютерами. Это поведение по умолчанию для Командных блоков ванильной игры.",
+    "gui.computercraft.config.default_computer_settings.tooltip": "Разделенный запятыми список системных настроек по умолчанию на новых компьютерах.\nНапример: \"shell.autocomplete=false,lua.autocomplete=false,edit.autocomplete=false\"\nотключит всё автодополнение.",
+    "gui.computercraft.config.execution.computer_threads.tooltip": "Устанавливает количество потоков, на которых работают компьютеры. Большее число\nозначает, что больше компьютеров сможет работать одновременно, но может привести к лагу.\nОбратите внимание, что некоторые моды могут не работать с более чем одним потоком. Используйте с осторожностью.\nОграничение: > 1",
+    "gui.computercraft.config.execution.max_main_computer_time.tooltip": "Идеальный максимум времени, которое отведено компьютеру на выполнение задач, в миллисекундах.\nМы вполне возможно выйдем за этот лимит, так как невозможно предсказать сколько\nвремени будет затрачено на выполнение задач, это лишь верхний лимит среднего значения времени.\nОграничение: > 1",
+    "gui.computercraft.config.execution.max_main_global_time.tooltip": "Максимум времени, которое может быть потрачено на выполнение задач за один тик, в \nмиллисекундах. \nМы вполне возможно выйдем за этот лимит, так как невозможно предсказать сколько\nвремени будет затрачено на выполнение задач, это лишь верхний лимит среднего значения времени.\nОграничение: > 1",
+    "gui.computercraft.config.http.bandwidth.global_download": "Глобальный лимит на скачивание",
+    "gui.computercraft.config.http.bandwidth.global_download.tooltip": "Количество байтов, которое можно скачать за секунду. Все компьютеры делят эту пропускную способность. (байты в секунду)\nОграничение: > 1",
+    "gui.computercraft.config.http.bandwidth.global_upload.tooltip": "Количество байтов, которое можно загрузить за секунду. Все компьютеры делят эту пропускную способность. (байты в секунду)\nОграничение: > 1",
+    "tracking_field.computercraft.http_requests.name": "HTTP запросы",
+    "tracking_field.computercraft.turtle_ops.name": "Операции Черепашек",
+    "gui.computercraft.config.http.enabled.tooltip": "Включить API \"http\" на Компьютерах. Это также отключает программы \"pastebin\" и \"wget\", \nкоторые нужны многим пользователям. Рекомендуется оставить это включенным и использовать \nконфиг \"rules\" для более тонкой настройки.",
+    "gui.computercraft.config.http.max_websockets.tooltip": "Количество одновременно открытых веб-сокетов, которые может иметь компьютер. Установите на 0 для неограниченных веб-сокетов.\nОграничение: > 1",
+    "gui.computercraft.config.term_sizes": "Размер терминала",
+    "gui.computercraft.config.term_sizes.computer.height": "Высота терминала",
+    "gui.computercraft.config.term_sizes.monitor.height": "Максимальная высота монитора",
+    "gui.computercraft.config.term_sizes.monitor.width.tooltip": "Ограничение: 1 ~ 32",
+    "gui.computercraft.config.turtle.advanced_fuel_limit": "Лимит топлива Продвинутых Черепашек",
+    "gui.computercraft.config.turtle.need_fuel.tooltip": "Устанавливает, нуждаются ли Черепашки в топливе для передвижения.",
+    "gui.computercraft.terminal": "Компьютерный терминал",
+    "tracking_field.computercraft.computer_tasks.name": "Задачи",
+    "tracking_field.computercraft.server_tasks.name": "Серверные задачи",
+    "gui.computercraft.upload.no_response": "Перенос файлов",
+    "tracking_field.computercraft.avg": "%s (среднее)",
+    "gui.computercraft.config.command_require_creative": "Для использования командных компьютеров нужен творческий режим",
+    "gui.computercraft.config.computer_space_limit": "Лимит места на компьютерах (в байтах)",
+    "gui.computercraft.config.computer_space_limit.tooltip": "Лимит места на дисках компьютеров и черепашек, в байтах.",
+    "gui.computercraft.config.default_computer_settings": "Настройки Компьютера по умолчанию",
+    "gui.computercraft.config.disable_lua51_features": "Отключить функции Lua 5.1",
+    "gui.computercraft.config.disable_lua51_features.tooltip": "Поставьте, чтобы отключить функции из Lua 5.1, которые будут убраны в будущих\nобновлениях. Полезно для того, чтобы улучшить совместимость вперед ваших программ.",
+    "gui.computercraft.config.execution": "Выполнение",
+    "gui.computercraft.config.execution.computer_threads": "Потоки компьютера",
+    "gui.computercraft.config.execution.max_main_global_time": "Глобальный лимит времени на тик сервера",
+    "gui.computercraft.config.execution.tooltip": "Контролирует поведение выполнения задач компьютеров. Эта настройка преднезначается для \nтонкой настройки серверов, и в основном не должна быть изменена.",
+    "gui.computercraft.config.floppy_space_limit": "Лимит места на дискетах (байты)",
+    "gui.computercraft.config.floppy_space_limit.tooltip": "Лимит места для хранения информации на дискетах, в байтах.",
+    "gui.computercraft.config.http": "HTTP",
+    "gui.computercraft.config.http.bandwidth": "Пропускная способность",
+    "gui.computercraft.config.http.bandwidth.global_upload": "Глобальный лимит загрузки",
+    "gui.computercraft.config.http.bandwidth.tooltip": "Ограничивает пропускную способность, используемую компьютерами.",
+    "gui.computercraft.config.http.enabled": "Включить HTTP API",
+    "gui.computercraft.config.http.max_requests": "Максимум одновременных запросов",
+    "gui.computercraft.config.http.max_requests.tooltip": "Количество http-запросов, которые компьютер может сделать одновременно. Дополнительные запросы \nбудут поставлены в очередь, и отправлены когда существующие запросы будут выполнены. Установите на 0 для \nнеограниченных запросов.\nОграничение: > 0",
+    "gui.computercraft.config.http.max_websockets": "Максимум одновременных веб-сокетов",
+    "gui.computercraft.config.term_sizes.computer": "Компьютер",
+    "gui.computercraft.config.term_sizes.computer.height.tooltip": "Ограничение: 1 ~ 255",
+    "gui.computercraft.config.term_sizes.computer.tooltip": "Размер терминала на компьютерах.",
+    "gui.computercraft.config.term_sizes.computer.width": "Ширина терминала",
+    "gui.computercraft.config.term_sizes.computer.width.tooltip": "Ограничение: 1 ~ 255",
+    "gui.computercraft.config.term_sizes.monitor": "Монитор",
+    "gui.computercraft.config.term_sizes.monitor.height.tooltip": "Ограничение: 1 ~ 32",
+    "gui.computercraft.config.term_sizes.monitor.tooltip": "Максимальный размер мониторов (в блоках).",
+    "gui.computercraft.config.term_sizes.monitor.width": "Максимальная ширина мониторов",
+    "gui.computercraft.config.term_sizes.pocket_computer.height": "Высота терминала",
+    "gui.computercraft.config.term_sizes.pocket_computer.height.tooltip": "Ограничение: 1 ~ 255",
+    "gui.computercraft.config.term_sizes.pocket_computer.width": "Ширина терминала",
+    "gui.computercraft.config.term_sizes.pocket_computer.width.tooltip": "Ограничение: 1 ~ 255",
+    "gui.computercraft.config.turtle": "Черепашки",
+    "gui.computercraft.config.turtle.advanced_fuel_limit.tooltip": "Лимит топлива для Продвинутых Черепашек.\nОграничение: > 0",
+    "gui.computercraft.config.turtle.need_fuel": "Включить механику топлива",
+    "gui.computercraft.config.turtle.normal_fuel_limit": "Лимит топлива Черепашек",
+    "gui.computercraft.config.turtle.normal_fuel_limit.tooltip": "Лимит топлива для Черепашек.\nОграничение: > 0",
+    "gui.computercraft.config.turtle.tooltip": "Разные настройки, связанные с черепашками."
 }

projects/common/src/main/resources/assets/computercraft/models/block/computer_on.json

@@ -0,0 +1,39 @@
+{
+    "parent": "minecraft:block/block",
+    "render_type": "cutout",
+    "textures": {
+        "particle": "#front"
+    },
+    "display": {
+        "firstperson_righthand": {
+            "rotation": [ 0, 135, 0 ],
+            "translation": [ 0, 0, 0 ],
+            "scale": [ 0.40, 0.40, 0.40 ]
+        }
+    },
+    "elements": [
+        {
+            "from": [ 0, 0, 0 ],
+            "to": [ 16, 16, 16 ],
+            "faces": {
+                "down":  { "texture": "#top",   "cullface": "down" },
+                "up":    { "texture": "#top",   "cullface": "up" },
+                "north": { "texture": "#front", "cullface": "north" },
+                "south": { "texture": "#side",  "cullface": "south" },
+                "west":  { "texture": "#side",  "cullface": "west" },
+                "east":  { "texture": "#side",  "cullface": "east" }
+            }
+        },
+        {
+            "from": [ 0, 0, 0 ],
+            "to": [ 16, 16, 16 ],
+            "faces": {
+                "north": {
+                    "texture": "#cursor",
+                    "cullface": "north",
+                    "forge_data": {"block_light": 15, "sky_light": 15}
+                }
+            }
+        }
+    ]
+}

projects/common/src/main/resources/assets/computercraft/models/block/computer_on.json.license

@@ -0,0 +1,3 @@
+SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+
+SPDX-License-Identifier: MPL-2.0

projects/common/src/main/resources/assets/computercraft/textures/block/computer_command_front_blink.png.mcmeta

@@ -1,6 +0,0 @@
-{
-  "animation": {
-    "frametime": 8,
-    "frames": [ 0, 1 ]
-  }
-}

projects/common/src/main/resources/assets/computercraft/textures/block/computer_normal_front_blink.png.mcmeta

@@ -1,6 +0,0 @@
-{
-  "animation": {
-    "frametime": 8,
-    "frames": [ 0, 1 ]
-  }
-}

projects/common/src/main/resources/assets/computercraft/textures/gui/turtle_upgrade_left.png.license

@@ -0,0 +1,3 @@
+SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+
+SPDX-License-Identifier: MPL-2.0

projects/common/src/main/resources/assets/computercraft/textures/gui/turtle_upgrade_right.png.license

@@ -0,0 +1,3 @@
+SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+
+SPDX-License-Identifier: MPL-2.0

projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java

@@ -58,6 +58,11 @@ import java.util.function.Predicate;
 
 @AutoService({ PlatformHelper.class, dan200.computercraft.impl.PlatformHelper.class, ComputerCraftAPIService.class })
 public class TestPlatformHelper extends AbstractComputerCraftAPI implements PlatformHelper {
+    @Override
+    public boolean isDevelopmentEnvironment() {
+        return true;
+    }
+
     @Override
     public ConfigFile.Builder createConfigBuilder() {
         throw new UnsupportedOperationException("Cannot create config file inside tests");

projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Turtle_Test.kt

@@ -32,11 +32,14 @@ import net.minecraft.world.item.ItemStack
 import net.minecraft.world.item.Items
 import net.minecraft.world.level.block.Blocks
 import net.minecraft.world.level.block.FenceBlock
+import net.minecraft.world.level.block.state.properties.BlockStateProperties
 import org.hamcrest.MatcherAssert.assertThat
-import org.hamcrest.Matchers.*
+import org.hamcrest.Matchers.array
+import org.hamcrest.Matchers.instanceOf
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertNotEquals
 import java.util.*
+import java.util.concurrent.CopyOnWriteArrayList
 import kotlin.time.Duration.Companion.milliseconds
 
 class Turtle_Test {
@@ -78,6 +81,26 @@ class Turtle_Test {
         thenExecute { helper.assertBlockPresent(Blocks.LAVA, BlockPos(2, 2, 2)) }
     }
 
+    /**
+     * Checks that calling [net.minecraft.world.item.Item.use] will not place blocks too far away.
+     *
+     * This is caused by items using [net.minecraft.world.item.Item.getPlayerPOVHitResult] to perform a ray trace, which
+     * ignores turtle's reduced reach distance.
+     *
+     * @see [#1497](https://github.com/cc-tweaked/CC-Tweaked/issues/1497)
+     */
+    @GameTest
+    fun Place_use_reach_limit(helper: GameTestHelper) = helper.sequence {
+        thenOnComputer {
+            turtle.placeDown(ObjectArguments()).await()
+                .assertArrayEquals(true, message = "Placed water")
+        }
+        thenExecute {
+            helper.assertBlockPresent(Blocks.AIR, BlockPos(2, 2, 2))
+            helper.assertBlockHas(BlockPos(2, 5, 2), BlockStateProperties.WATERLOGGED, true)
+        }
+    }
+
     /**
      * Checks turtles can place when waterlogged.
      *
@@ -466,7 +489,7 @@ class Turtle_Test {
     fun Peripheral_change(helper: GameTestHelper) = helper.sequence {
         val testInfo = (helper as GameTestHelperAccessor).testInfo as GameTestInfoAccessor
 
-        val events = mutableListOf<Pair<String, String>>()
+        val events = CopyOnWriteArrayList<Pair<String, String>>()
         var running = false
         thenStartComputer("listen") {
             running = true
@@ -485,15 +508,13 @@ class Turtle_Test {
             turtle.back().await().assertArrayEquals(true, message = "Moved turtle forward")
             TestHooks.LOG.info("[{}] Finished turtle at {}", testInfo, testInfo.`computercraft$getTick`())
         }
-        thenIdle(4) // Should happen immediately, but computers might be slow.
-        thenExecute {
-            assertEquals(
-                listOf(
-                    "peripheral_detach" to "right",
-                    "peripheral" to "right",
-                ),
-                events,
+        thenWaitUntil {
+            val expected = listOf(
+                "peripheral_detach" to "right",
+                "peripheral" to "right",
             )
+
+            if (events != expected) helper.fail("Expected $expected, but received $events")
         }
     }
 

projects/common/src/testMod/resources/data/cctest/structures/turtle_test.place_use_reach_limit.snbt

@@ -0,0 +1,139 @@
+{
+    DataVersion: 3337,
+    size: [5, 5, 5],
+    data: [
+        {pos: [0, 0, 0], state: "minecraft:polished_andesite"},
+        {pos: [0, 0, 1], state: "minecraft:polished_andesite"},
+        {pos: [0, 0, 2], state: "minecraft:polished_andesite"},
+        {pos: [0, 0, 3], state: "minecraft:polished_andesite"},
+        {pos: [0, 0, 4], state: "minecraft:polished_andesite"},
+        {pos: [1, 0, 0], state: "minecraft:polished_andesite"},
+        {pos: [1, 0, 1], state: "minecraft:polished_andesite"},
+        {pos: [1, 0, 2], state: "minecraft:polished_andesite"},
+        {pos: [1, 0, 3], state: "minecraft:polished_andesite"},
+        {pos: [1, 0, 4], state: "minecraft:polished_andesite"},
+        {pos: [2, 0, 0], state: "minecraft:polished_andesite"},
+        {pos: [2, 0, 1], state: "minecraft:polished_andesite"},
+        {pos: [2, 0, 2], state: "minecraft:polished_andesite"},
+        {pos: [2, 0, 3], state: "minecraft:polished_andesite"},
+        {pos: [2, 0, 4], state: "minecraft:polished_andesite"},
+        {pos: [3, 0, 0], state: "minecraft:polished_andesite"},
+        {pos: [3, 0, 1], state: "minecraft:polished_andesite"},
+        {pos: [3, 0, 2], state: "minecraft:polished_andesite"},
+        {pos: [3, 0, 3], state: "minecraft:polished_andesite"},
+        {pos: [3, 0, 4], state: "minecraft:polished_andesite"},
+        {pos: [4, 0, 0], state: "minecraft:polished_andesite"},
+        {pos: [4, 0, 1], state: "minecraft:polished_andesite"},
+        {pos: [4, 0, 2], state: "minecraft:polished_andesite"},
+        {pos: [4, 0, 3], state: "minecraft:polished_andesite"},
+        {pos: [4, 0, 4], state: "minecraft:polished_andesite"},
+        {pos: [0, 1, 0], state: "minecraft:air"},
+        {pos: [0, 1, 1], state: "minecraft:air"},
+        {pos: [0, 1, 2], state: "minecraft:air"},
+        {pos: [0, 1, 3], state: "minecraft:air"},
+        {pos: [0, 1, 4], state: "minecraft:air"},
+        {pos: [1, 1, 0], state: "minecraft:air"},
+        {pos: [1, 1, 1], state: "minecraft:air"},
+        {pos: [1, 1, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 1, 3], state: "minecraft:air"},
+        {pos: [1, 1, 4], state: "minecraft:air"},
+        {pos: [2, 1, 0], state: "minecraft:air"},
+        {pos: [2, 1, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 1, 2], state: "minecraft:air"},
+        {pos: [2, 1, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 1, 4], state: "minecraft:air"},
+        {pos: [3, 1, 0], state: "minecraft:air"},
+        {pos: [3, 1, 1], state: "minecraft:air"},
+        {pos: [3, 1, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 1, 3], state: "minecraft:air"},
+        {pos: [3, 1, 4], state: "minecraft:air"},
+        {pos: [4, 1, 0], state: "minecraft:air"},
+        {pos: [4, 1, 1], state: "minecraft:air"},
+        {pos: [4, 1, 2], state: "minecraft:air"},
+        {pos: [4, 1, 3], state: "minecraft:air"},
+        {pos: [4, 1, 4], state: "minecraft:air"},
+        {pos: [0, 2, 0], state: "minecraft:air"},
+        {pos: [0, 2, 1], state: "minecraft:air"},
+        {pos: [0, 2, 2], state: "minecraft:air"},
+        {pos: [0, 2, 3], state: "minecraft:air"},
+        {pos: [0, 2, 4], state: "minecraft:air"},
+        {pos: [1, 2, 0], state: "minecraft:air"},
+        {pos: [1, 2, 1], state: "minecraft:air"},
+        {pos: [1, 2, 2], state: "minecraft:air"},
+        {pos: [1, 2, 3], state: "minecraft:air"},
+        {pos: [1, 2, 4], state: "minecraft:air"},
+        {pos: [2, 2, 0], state: "minecraft:air"},
+        {pos: [2, 2, 1], state: "minecraft:air"},
+        {pos: [2, 2, 2], state: "minecraft:ladder{facing:north,waterlogged:false}"},
+        {pos: [2, 2, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 2, 4], state: "minecraft:air"},
+        {pos: [3, 2, 0], state: "minecraft:air"},
+        {pos: [3, 2, 1], state: "minecraft:air"},
+        {pos: [3, 2, 2], state: "minecraft:air"},
+        {pos: [3, 2, 3], state: "minecraft:air"},
+        {pos: [3, 2, 4], state: "minecraft:air"},
+        {pos: [4, 2, 0], state: "minecraft:air"},
+        {pos: [4, 2, 1], state: "minecraft:air"},
+        {pos: [4, 2, 2], state: "minecraft:air"},
+        {pos: [4, 2, 3], state: "minecraft:air"},
+        {pos: [4, 2, 4], state: "minecraft:air"},
+        {pos: [0, 3, 0], state: "minecraft:air"},
+        {pos: [0, 3, 1], state: "minecraft:air"},
+        {pos: [0, 3, 2], state: "minecraft:air"},
+        {pos: [0, 3, 3], state: "minecraft:air"},
+        {pos: [0, 3, 4], state: "minecraft:air"},
+        {pos: [1, 3, 0], state: "minecraft:air"},
+        {pos: [1, 3, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 3, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 3, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 3, 4], state: "minecraft:air"},
+        {pos: [2, 3, 0], state: "minecraft:air"},
+        {pos: [2, 3, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 3, 2], state: "minecraft:air"},
+        {pos: [2, 3, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 3, 4], state: "minecraft:air"},
+        {pos: [3, 3, 0], state: "minecraft:air"},
+        {pos: [3, 3, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 3, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 3, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 3, 4], state: "minecraft:air"},
+        {pos: [4, 3, 0], state: "minecraft:air"},
+        {pos: [4, 3, 1], state: "minecraft:air"},
+        {pos: [4, 3, 2], state: "minecraft:air"},
+        {pos: [4, 3, 3], state: "minecraft:air"},
+        {pos: [4, 3, 4], state: "minecraft:air"},
+        {pos: [0, 4, 0], state: "minecraft:air"},
+        {pos: [0, 4, 1], state: "minecraft:air"},
+        {pos: [0, 4, 2], state: "minecraft:air"},
+        {pos: [0, 4, 3], state: "minecraft:air"},
+        {pos: [0, 4, 4], state: "minecraft:air"},
+        {pos: [1, 4, 0], state: "minecraft:air"},
+        {pos: [1, 4, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 4, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 4, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [1, 4, 4], state: "minecraft:air"},
+        {pos: [2, 4, 0], state: "minecraft:air"},
+        {pos: [2, 4, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 4, 2], state: "computercraft:turtle_normal{facing:north,waterlogged:false}", nbt: {ComputerId: 1, Fuel: 0, Items: [{Count: 1b, Slot: 0b, id: "minecraft:water_bucket"}], Label: "turtle_test.place_use_reach_limit", On: 1b, Slot: 0, id: "computercraft:turtle_normal"}},
+        {pos: [2, 4, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [2, 4, 4], state: "minecraft:air"},
+        {pos: [3, 4, 0], state: "minecraft:air"},
+        {pos: [3, 4, 1], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 4, 2], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 4, 3], state: "minecraft:light_gray_stained_glass"},
+        {pos: [3, 4, 4], state: "minecraft:air"},
+        {pos: [4, 4, 0], state: "minecraft:air"},
+        {pos: [4, 4, 1], state: "minecraft:air"},
+        {pos: [4, 4, 2], state: "minecraft:air"},
+        {pos: [4, 4, 3], state: "minecraft:air"},
+        {pos: [4, 4, 4], state: "minecraft:air"}
+    ],
+    entities: [],
+    palette: [
+        "minecraft:polished_andesite",
+        "minecraft:light_gray_stained_glass",
+        "minecraft:air",
+        "minecraft:ladder{facing:north,waterlogged:false}",
+        "computercraft:turtle_normal{facing:north,waterlogged:false}"
+    ]
+}

projects/core-api/src/main/java/dan200/computercraft/api/lua/IArguments.java

@@ -479,9 +479,11 @@ public interface IArguments {
      * yourself.
      *
      * @return An {@link IArguments} instance which can escape the current scope. May be {@code this}.
-     * @throws LuaException For the same reasons as {@link #get(int)}.
+     * @throws LuaException          For the same reasons as {@link #get(int)}.
+     * @throws IllegalStateException If marking these arguments as escaping outside the scope of the original function.
      */
     default IArguments escapes() throws LuaException {
+        // TODO(1.21.0): Make this return void, require that it mutates this.
         return this;
     }
 }

projects/core/src/main/java/dan200/computercraft/core/ComputerContext.java

@@ -4,13 +4,26 @@
 
 package dan200.computercraft.core;
 
+import dan200.computercraft.api.lua.ILuaAPIFactory;
+import dan200.computercraft.core.asm.GenericMethod;
+import dan200.computercraft.core.asm.LuaMethodSupplier;
+import dan200.computercraft.core.asm.PeripheralMethodSupplier;
 import dan200.computercraft.core.computer.ComputerThread;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.computer.mainthread.MainThreadScheduler;
+import dan200.computercraft.core.computer.mainthread.NoWorkMainThreadScheduler;
 import dan200.computercraft.core.lua.CobaltLuaMachine;
 import dan200.computercraft.core.lua.ILuaMachine;
+import dan200.computercraft.core.lua.MachineEnvironment;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 
 import javax.annotation.CheckReturnValue;
+import javax.annotation.Nullable;
+import java.util.Collection;
+import java.util.List;
+import java.util.Objects;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -20,27 +33,24 @@ public final class ComputerContext {
     private final GlobalEnvironment globalEnvironment;
     private final ComputerThread computerScheduler;
     private final MainThreadScheduler mainThreadScheduler;
-    private final ILuaMachine.Factory factory;
+    private final ILuaMachine.Factory luaFactory;
+    private final List<ILuaAPIFactory> apiFactories;
+    private final MethodSupplier<LuaMethod> luaMethods;
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
 
-    public ComputerContext(
+    ComputerContext(
         GlobalEnvironment globalEnvironment, ComputerThread computerScheduler,
-        MainThreadScheduler mainThreadScheduler, ILuaMachine.Factory factory
+        MainThreadScheduler mainThreadScheduler, ILuaMachine.Factory luaFactory,
+        List<ILuaAPIFactory> apiFactories, MethodSupplier<LuaMethod> luaMethods,
+        MethodSupplier<PeripheralMethod> peripheralMethods
     ) {
         this.globalEnvironment = globalEnvironment;
         this.computerScheduler = computerScheduler;
         this.mainThreadScheduler = mainThreadScheduler;
-        this.factory = factory;
-    }
-
-    /**
-     * Create a default {@link ComputerContext} with the given global environment.
-     *
-     * @param environment         The current global environment.
-     * @param threads             The number of threads to use for the {@link #computerScheduler()}
-     * @param mainThreadScheduler The main thread scheduler to use.
-     */
-    public ComputerContext(GlobalEnvironment environment, int threads, MainThreadScheduler mainThreadScheduler) {
-        this(environment, new ComputerThread(threads), mainThreadScheduler, CobaltLuaMachine::new);
+        this.luaFactory = luaFactory;
+        this.apiFactories = apiFactories;
+        this.luaMethods = luaMethods;
+        this.peripheralMethods = peripheralMethods;
     }
 
     /**
@@ -77,7 +87,35 @@ public final class ComputerContext {
      * @return The current Lua machine factory.
      */
     public ILuaMachine.Factory luaFactory() {
-        return factory;
+        return luaFactory;
+    }
+
+    /**
+     * Additional APIs to inject into each computer.
+     *
+     * @return All available API factories.
+     */
+    public List<ILuaAPIFactory> apiFactories() {
+        return apiFactories;
+    }
+
+    /**
+     * Get the {@link MethodSupplier} used to find methods on Lua values.
+     *
+     * @return The {@link LuaMethod} method supplier.
+     * @see MachineEnvironment#luaMethods()
+     */
+    public MethodSupplier<LuaMethod> luaMethods() {
+        return luaMethods;
+    }
+
+    /**
+     * Get the {@link MethodSupplier} used to find methods on peripherals.
+     *
+     * @return The {@link PeripheralMethod} method supplier.
+     */
+    public MethodSupplier<PeripheralMethod> peripheralMethods() {
+        return peripheralMethods;
     }
 
     /**
@@ -106,4 +144,119 @@ public final class ComputerContext {
             throw new IllegalStateException("Failed to shutdown ComputerContext in time.");
         }
     }
+
+    /**
+     * Create a new {@linkplain Builder builder} for a computer context.
+     *
+     * @param environment The {@linkplain ComputerContext#globalEnvironment() global environment} for this context.
+     * @return The builder for a new context.
+     */
+    public static Builder builder(GlobalEnvironment environment) {
+        return new Builder(environment);
+    }
+
+    /**
+     * A builder for a {@link ComputerContext}.
+     *
+     * @see ComputerContext#builder(GlobalEnvironment)
+     */
+    public static class Builder {
+        private final GlobalEnvironment environment;
+        private int threads = 1;
+        private @Nullable MainThreadScheduler mainThreadScheduler;
+        private @Nullable ILuaMachine.Factory luaFactory;
+        private @Nullable List<ILuaAPIFactory> apiFactories;
+        private @Nullable List<GenericMethod> genericMethods;
+
+        Builder(GlobalEnvironment environment) {
+            this.environment = environment;
+        }
+
+        /**
+         * Set the number of threads the {@link ComputerThread} will use.
+         *
+         * @param threads The number of threads to use.
+         * @return {@code this}, for chaining
+         * @see ComputerContext#computerScheduler()
+         */
+        public Builder computerThreads(int threads) {
+            if (threads < 1) throw new IllegalArgumentException("Threads must be >= 1");
+            this.threads = threads;
+            return this;
+        }
+
+        /**
+         * Set the {@link MainThreadScheduler} for this context.
+         *
+         * @param scheduler The main thread scheduler.
+         * @return {@code this}, for chaining
+         * @see ComputerContext#mainThreadScheduler()
+         */
+        public Builder mainThreadScheduler(MainThreadScheduler scheduler) {
+            Objects.requireNonNull(scheduler);
+            if (mainThreadScheduler != null) throw new IllegalStateException("Main-thread scheduler already specified");
+            mainThreadScheduler = scheduler;
+            return this;
+        }
+
+        /**
+         * Set the {@link ILuaMachine.Factory} for this context.
+         *
+         * @param factory The Lua machine factory.
+         * @return {@code this}, for chaining
+         * @see ComputerContext#luaFactory()
+         */
+        public Builder luaFactory(ILuaMachine.Factory factory) {
+            Objects.requireNonNull(factory);
+            if (luaFactory != null) throw new IllegalStateException("Main-thread scheduler already specified");
+            luaFactory = factory;
+            return this;
+        }
+
+        /**
+         * Set the additional {@linkplain ILuaAPIFactory APIs} to add to each computer.
+         *
+         * @param apis A list of API factories.
+         * @return {@code this}, for chaining
+         * @see ComputerContext#apiFactories()
+         */
+        public Builder apiFactories(Collection<ILuaAPIFactory> apis) {
+            Objects.requireNonNull(apis);
+            if (apiFactories != null) throw new IllegalStateException("Main-thread scheduler already specified");
+            apiFactories = List.copyOf(apis);
+            return this;
+        }
+
+        /**
+         * Set the set of {@link GenericMethod}s used by the {@linkplain MethodSupplier method suppliers}.
+         *
+         * @param genericMethods A list of API factories.
+         * @return {@code this}, for chaining
+         * @see ComputerContext#luaMethods()
+         * @see ComputerContext#peripheralMethods()
+         */
+        public Builder genericMethods(Collection<GenericMethod> genericMethods) {
+            Objects.requireNonNull(genericMethods);
+            if (this.genericMethods != null) throw new IllegalStateException("Main-thread scheduler already specified");
+            this.genericMethods = List.copyOf(genericMethods);
+            return this;
+        }
+
+        /**
+         * Create a new {@link ComputerContext}.
+         *
+         * @return The newly created context.
+         */
+        public ComputerContext build() {
+            return new ComputerContext(
+                environment,
+                new ComputerThread(threads),
+                mainThreadScheduler == null ? new NoWorkMainThreadScheduler() : mainThreadScheduler,
+                luaFactory == null ? CobaltLuaMachine::new : luaFactory,
+                apiFactories == null ? List.of() : apiFactories,
+                LuaMethodSupplier.create(genericMethods == null ? List.of() : genericMethods),
+                PeripheralMethodSupplier.create(genericMethods == null ? List.of() : genericMethods)
+            );
+        }
+    }
 }

projects/core/src/main/java/dan200/computercraft/core/apis/FSAPI.java

@@ -443,28 +443,6 @@ public class FSAPI implements ILuaAPI {
         }
     }
 
-    /**
-     * Searches for files matching a string with wildcards.
-     * <p>
-     * This string is formatted like a normal path string, but can include any
-     * number of wildcards ({@code *}) to look for files matching anything.
-     * For example, <code>rom/&#42;/command*</code> will look for any path starting with
-     * {@code command} inside any subdirectory of {@code /rom}.
-     *
-     * @param path The wildcard-qualified path to search for.
-     * @return A list of paths that match the search string.
-     * @throws LuaException If the path doesn't exist.
-     * @cc.since 1.6
-     */
-    @LuaFunction
-    public final String[] find(String path) throws LuaException {
-        try (var ignored = environment.time(Metrics.FS_OPS)) {
-            return getFileSystem().find(path);
-        } catch (FileSystemException e) {
-            throw new LuaException(e.getMessage());
-        }
-    }
-
     /**
      * Returns the capacity of the drive the path is located on.
      *

projects/core/src/main/java/dan200/computercraft/core/apis/IAPIEnvironment.java

@@ -10,9 +10,9 @@ import dan200.computercraft.core.computer.ComputerEnvironment;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.filesystem.FileSystem;
-import dan200.computercraft.core.metrics.OperationTimer;
 import dan200.computercraft.core.metrics.Metric;
 import dan200.computercraft.core.metrics.MetricsObserver;
+import dan200.computercraft.core.metrics.OperationTimer;
 import dan200.computercraft.core.terminal.Terminal;
 
 import javax.annotation.Nullable;

projects/core/src/main/java/dan200/computercraft/core/apis/PeripheralAPI.java

@@ -7,13 +7,12 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.filesystem.Mount;
 import dan200.computercraft.api.filesystem.WritableMount;
 import dan200.computercraft.api.lua.*;
-import dan200.computercraft.api.peripheral.IDynamicPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.NotAttachedException;
 import dan200.computercraft.api.peripheral.WorkMonitor;
-import dan200.computercraft.core.asm.LuaMethod;
-import dan200.computercraft.core.asm.PeripheralMethod;
 import dan200.computercraft.core.computer.ComputerSide;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.core.metrics.Metrics;
 import dan200.computercraft.core.util.LuaUtil;
 
@@ -44,7 +43,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             type = Objects.requireNonNull(peripheral.getType(), "Peripheral type cannot be null");
             additionalTypes = peripheral.getAdditionalTypes();
 
-            methodMap = PeripheralAPI.getMethods(peripheral);
+            methodMap = peripheralMethods.getSelfMethods(peripheral);
         }
 
         public IPeripheral getPeripheral() {
@@ -172,11 +171,13 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     }
 
     private final IAPIEnvironment environment;
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
     private final PeripheralWrapper[] peripherals = new PeripheralWrapper[6];
     private boolean running;
 
-    public PeripheralAPI(IAPIEnvironment environment) {
+    public PeripheralAPI(IAPIEnvironment environment, MethodSupplier<PeripheralMethod> peripheralMethods) {
         this.environment = environment;
+        this.peripheralMethods = peripheralMethods;
         this.environment.setPeripheralChangeListener(this);
         running = false;
     }
@@ -315,21 +316,4 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             throw e;
         }
     }
-
-    public static Map<String, PeripheralMethod> getMethods(IPeripheral peripheral) {
-        var dynamicMethods = peripheral instanceof IDynamicPeripheral
-            ? Objects.requireNonNull(((IDynamicPeripheral) peripheral).getMethodNames(), "Peripheral methods cannot be null")
-            : LuaMethod.EMPTY_METHODS;
-
-        var methods = PeripheralMethod.GENERATOR.getMethods(peripheral.getClass());
-
-        Map<String, PeripheralMethod> methodMap = new HashMap<>(methods.size() + dynamicMethods.length);
-        for (var i = 0; i < dynamicMethods.length; i++) {
-            methodMap.put(dynamicMethods[i], PeripheralMethod.DYNAMIC.get(i));
-        }
-        for (var method : methods) {
-            methodMap.put(method.getName(), method.getMethod());
-        }
-        return methodMap;
-    }
 }

projects/core/src/main/java/dan200/computercraft/core/apis/TableHelper.java

@@ -103,7 +103,7 @@ public final class TableHelper {
 
     public static Optional<Double> optRealField(Map<?, ?> table, String key) throws LuaException {
         var value = table.get(key);
-        if(value == null) {
+        if (value == null) {
             return Optional.empty();
         } else {
             return Optional.of(getRealField(table, key));

projects/core/src/main/java/dan200/computercraft/core/apis/http/NetworkUtils.java

@@ -27,7 +27,6 @@ import io.netty.handler.ssl.SslHandler;
 import io.netty.handler.timeout.ReadTimeoutException;
 import io.netty.handler.traffic.AbstractTrafficShapingHandler;
 import io.netty.handler.traffic.GlobalTrafficShapingHandler;
-import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -193,7 +192,7 @@ public final class NetworkUtils {
      * @return The SSL handler.
      * @see io.netty.handler.ssl.SslHandler
      */
-    private static SslHandler makeSslHandler(SocketChannel ch, @NotNull SslContext sslContext, int timeout, String peerHost, int peerPort) {
+    private static SslHandler makeSslHandler(SocketChannel ch, SslContext sslContext, int timeout, String peerHost, int peerPort) {
         var handler = sslContext.newHandler(ch.alloc(), peerHost, peerPort);
         if (timeout > 0) handler.setHandshakeTimeoutMillis(timeout);
         return handler;