diff --git a/.gitignore b/.gitignore
index c02ff0042..55e79e03e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,11 +2,12 @@
 /classes
 /logs
 /build
+/projects/*/build
 /buildSrc/build
 /out
 /doc/out/
 /node_modules
-/.jqwik-database
+.jqwik-database
 
 # Runtime directories
 /run
diff --git a/build.gradle.kts b/build.gradle.kts
index ed59fe649..87c59def3 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -9,7 +9,6 @@ plugins {
     alias(libs.plugins.librarian)
     alias(libs.plugins.shadow)
     // Publishing
-    `maven-publish`
     alias(libs.plugins.curseForgeGradle)
     alias(libs.plugins.githubRelease)
     alias(libs.plugins.minotaur)
@@ -19,6 +18,7 @@ plugins {
     id("cc-tweaked.illuaminate")
     id("cc-tweaked.node")
     id("cc-tweaked.gametest")
+    id("cc-tweaked.publishing")
     id("cc-tweaked")
 }
 
@@ -26,9 +26,10 @@ val isStable = true
 val modVersion: String by extra
 val mcVersion: String by extra
 
-group = "org.squiddev"
-version = modVersion
-base.archivesName.set("cc-tweaked-$mcVersion")
+val allProjects = listOf(":core-api").map { evaluationDependsOn(it) }
+cct {
+    allProjects.forEach { externalSources(it) }
+}
 
 java.registerFeature("extraMods") { usingSourceSet(sourceSets.main.get()) }
 
@@ -52,7 +53,11 @@ minecraft {
 
             forceExit = false
 
-            mods.register("computercraft") { source(sourceSets.main.get()) }
+            mods.register("computercraft") {
+                cct.sourceDirectories.get().forEach {
+                    if (it.classes) sources(it.sourceSet)
+                }
+            }
         }
 
         val client by registering {
@@ -149,6 +154,7 @@ dependencies {
     "extraModsRuntimeOnly"(fg.deobf("mezz.jei:jei-1.19.2-forge:11.3.0.262"))
     "extraModsCompileOnly"(fg.deobf("maven.modrinth:oculus:1.2.5"))
 
+    implementation(project(":core-api"))
     "shade"(libs.cobalt)
     "shade"("io.netty:netty-codec-http:4.1.76.Final")
 
@@ -170,7 +176,6 @@ illuaminate {
 
 tasks.javadoc {
     include("dan200/computercraft/api/**/*.java")
-    (options as StandardJavadocDocletOptions).links("https://docs.oracle.com/en/java/javase/17/docs/api/")
 }
 
 val apiJar by tasks.registering(Jar::class) {
@@ -216,21 +221,10 @@ tasks.processResources {
 }
 
 tasks.jar {
-    isReproducibleFileOrder = true
-    isPreserveFileTimestamps = false
     finalizedBy("reobfJar")
     archiveClassifier.set("slim")
 
-    manifest {
-        attributes(
-            "Specification-Title" to "computercraft",
-            "Specification-Vendor" to "SquidDev",
-            "Specification-Version" to "1",
-            "Implementation-Title" to "cctweaked",
-            "Implementation-Version" to modVersion,
-            "Implementation-Vendor" to "SquidDev",
-        )
-    }
+    from(allProjects.map { zipTree(it.tasks.jar.get().archiveFile) })
 }
 
 tasks.shadowJar {
@@ -374,7 +368,8 @@ val publishCurseForge by tasks.registering(TaskPublishCurseForge::class) {
 
     val mainFile = upload("282001", tasks.shadowJar.get().archiveFile)
     dependsOn(tasks.shadowJar) // Ughr.
-    mainFile.changelog = "Release notes can be found on the [GitHub repository](https://github.com/cc-tweaked/CC-Tweaked/releases/tag/v$mcVersion-$modVersion)."
+    mainFile.changelog =
+        "Release notes can be found on the [GitHub repository](https://github.com/cc-tweaked/CC-Tweaked/releases/tag/v$mcVersion-$modVersion)."
     mainFile.changelogType = "markdown"
     mainFile.releaseType = if (isStable) "release" else "alpha"
     mainFile.gameVersions.add(mcVersion)
@@ -420,41 +415,9 @@ tasks.publish { dependsOn(tasks.githubRelease) }
 
 publishing {
     publications {
-        register<MavenPublication>("maven") {
-            artifactId = base.archivesName.get()
-            from(components["java"])
+        named("maven", MavenPublication::class) {
             artifact(apiJar)
             fg.component(this)
-
-            pom {
-                name.set("CC: Tweaked")
-                description.set("CC: Tweaked is a fork of ComputerCraft, adding programmable computers, turtles and more to Minecraft.")
-                url.set("https://github.com/cc-tweaked/CC-Tweaked")
-
-                scm {
-                    url.set("https://github.com/cc-tweaked/CC-Tweaked.git")
-                }
-
-                issueManagement {
-                    system.set("github")
-                    url.set("https://github.com/cc-tweaked/CC-Tweaked/issues")
-                }
-
-                licenses {
-                    license {
-                        name.set("ComputerCraft Public License, Version 1.0")
-                        url.set("https://github.com/cc-tweaked/CC-Tweaked/blob/HEAD/LICENSE")
-                    }
-                }
-            }
-        }
-    }
-
-    repositories {
-        maven("https://squiddev.cc/maven") {
-            name = "SquidDev"
-
-            credentials(PasswordCredentials::class)
         }
     }
 }
diff --git a/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts b/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
index e52bbf060..0fa97dc73 100644
--- a/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
+++ b/buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts
@@ -11,6 +11,17 @@ plugins {
     id("com.diffplug.spotless")
 }
 
+val modVersion: String by extra
+val mcVersion: String by extra
+
+group = "cc.tweaked"
+version = modVersion
+
+base.archivesName.convention(
+    // TODO: Remove this (and the one below) once we've no longer got a root project!
+    if (project.path == rootProject.path) "cc-tweaked-$mcVersion" else "cc-tweaked-$mcVersion-${project.name}",
+)
+
 java {
     toolchain {
         languageVersion.set(CCTweakedPlugin.JAVA_VERSION)
@@ -53,6 +64,31 @@ tasks.withType(JavaCompile::class.java).configureEach {
     options.encoding = "UTF-8"
 }
 
+tasks.jar {
+    isReproducibleFileOrder = true
+    isPreserveFileTimestamps = false
+    archiveClassifier.set("slim")
+
+    manifest {
+        attributes(
+            "Specification-Title" to "computercraft",
+            "Specification-Vendor" to "SquidDev",
+            "Specification-Version" to "1",
+            "Implementation-Title" to (if (project.path == rootProject.path) "cctweaked" else "cctweaked-${project.name}"),
+            "Implementation-Version" to modVersion,
+            "Implementation-Vendor" to "SquidDev",
+        )
+    }
+}
+
+tasks.javadoc {
+    options {
+        val stdOptions = this as StandardJavadocDocletOptions
+        stdOptions.addBooleanOption("Xdoclint:all,-missing", true)
+        stdOptions.links("https://docs.oracle.com/en/java/javase/17/docs/api/")
+    }
+}
+
 tasks.test {
     finalizedBy("jacocoTestReport")
 
@@ -78,8 +114,8 @@ spotless {
     }
 
     val licenser = LicenseHeader.create(
-        api = file("config/license/api.txt"),
-        main = file("config/license/main.txt"),
+        api = rootProject.file("config/license/api.txt"),
+        main = rootProject.file("config/license/main.txt"),
     )
 
     java {
diff --git a/buildSrc/src/main/kotlin/cc-tweaked.publishing.gradle.kts b/buildSrc/src/main/kotlin/cc-tweaked.publishing.gradle.kts
new file mode 100644
index 000000000..b1f27fe9c
--- /dev/null
+++ b/buildSrc/src/main/kotlin/cc-tweaked.publishing.gradle.kts
@@ -0,0 +1,45 @@
+import org.gradle.kotlin.dsl.`maven-publish`
+
+plugins {
+    `java-library`
+    `maven-publish`
+}
+
+publishing {
+    publications {
+        register<MavenPublication>("maven") {
+            artifactId = base.archivesName.get()
+            from(components["java"])
+
+            pom {
+                name.set("CC: Tweaked")
+                description.set("CC: Tweaked is a fork of ComputerCraft, adding programmable computers, turtles and more to Minecraft.")
+                url.set("https://github.com/cc-tweaked/CC-Tweaked")
+
+                scm {
+                    url.set("https://github.com/cc-tweaked/CC-Tweaked.git")
+                }
+
+                issueManagement {
+                    system.set("github")
+                    url.set("https://github.com/cc-tweaked/CC-Tweaked/issues")
+                }
+
+                licenses {
+                    license {
+                        name.set("ComputerCraft Public License, Version 1.0")
+                        url.set("https://github.com/cc-tweaked/CC-Tweaked/blob/HEAD/LICENSE")
+                    }
+                }
+            }
+        }
+    }
+
+    repositories {
+        maven("https://squiddev.cc/maven") {
+            name = "SquidDev"
+
+            credentials(PasswordCredentials::class)
+        }
+    }
+}
diff --git a/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedExtension.kt b/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedExtension.kt
index e87d3acab..782c178b5 100644
--- a/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedExtension.kt
+++ b/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedExtension.kt
@@ -5,6 +5,7 @@
 import org.gradle.api.attributes.TestSuiteType
 import org.gradle.api.file.FileSystemOperations
 import org.gradle.api.provider.Provider
+import org.gradle.api.provider.SetProperty
 import org.gradle.api.reporting.ReportingExtension
 import org.gradle.api.tasks.JavaExec
 import org.gradle.api.tasks.SourceSetContainer
@@ -31,7 +32,8 @@ abstract class CCTweakedExtension(
 
     /** Get the current git branch. */
     val gitBranch: Provider<String> = gitProvider(project, "<no git branch>") {
-        ProcessHelpers.captureOut("git", "-C", project.projectDir.absolutePath, "rev-parse", "--abbrev-ref", "HEAD").trim()
+        ProcessHelpers.captureOut("git", "-C", project.projectDir.absolutePath, "rev-parse", "--abbrev-ref", "HEAD")
+            .trim()
     }
 
     /** Get a list of all contributors to the project. */
@@ -64,6 +66,30 @@ abstract class CCTweakedExtension(
         contributors.sortedWith(String.CASE_INSENSITIVE_ORDER)
     }
 
+    /**
+     * References to other sources
+     */
+    val sourceDirectories: SetProperty<SourceSetReference> =
+        project.objects.setProperty(SourceSetReference::class.java)
+
+    /** All source sets referenced by this project. */
+    val sourceSets = sourceDirectories.map { x -> x.map { it.sourceSet } }
+
+    init {
+        sourceDirectories.finalizeValueOnRead()
+    }
+
+    /**
+     * Mark this project as consuming another project. Its [sourceDirectories] are added, ensuring tasks are set up
+     * correctly.
+     */
+    fun externalSources(project: Project) {
+        val otherCct = project.extensions.getByType(CCTweakedExtension::class.java)
+        for (sourceSet in otherCct.sourceSets.get()) {
+            sourceDirectories.add(SourceSetReference.external(sourceSet))
+        }
+    }
+
     fun jacoco(task: NamedDomainObjectProvider<JavaExec>) {
         val classDump = project.buildDir.resolve("jacocoClassDump/${task.name}")
         val reportTaskName = "jacoco${task.name.capitalized()}Report"
diff --git a/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedPlugin.kt b/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedPlugin.kt
index 19716208f..8286c12d0 100644
--- a/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedPlugin.kt
+++ b/buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedPlugin.kt
@@ -2,14 +2,28 @@
 
 import org.gradle.api.Plugin
 import org.gradle.api.Project
+import org.gradle.api.tasks.SourceSetContainer
 import org.gradle.jvm.toolchain.JavaLanguageVersion
+import org.gradle.testing.jacoco.tasks.JacocoReport
 
 /**
  * Configures projects to match a shared configuration.
  */
 class CCTweakedPlugin : Plugin<Project> {
     override fun apply(project: Project) {
-        project.extensions.create("cct", CCTweakedExtension::class.java)
+        val sourceSets = project.extensions.getByType(SourceSetContainer::class.java)
+
+        val cct = project.extensions.create("cct", CCTweakedExtension::class.java)
+        cct.sourceDirectories.add(SourceSetReference.internal(sourceSets.getByName("main")))
+
+        project.afterEvaluate {
+            cct.sourceDirectories.disallowChanges()
+        }
+
+        // Set up jacoco to read from /all/ our source directories.
+        project.tasks.named("jacocoTestReport", JacocoReport::class.java) {
+            for (ref in cct.sourceSets.get()) sourceDirectories.from(ref.allSource.sourceDirectories)
+        }
     }
 
     companion object {
diff --git a/buildSrc/src/main/kotlin/cc/tweaked/gradle/SourceSetReference.kt b/buildSrc/src/main/kotlin/cc/tweaked/gradle/SourceSetReference.kt
new file mode 100644
index 000000000..1668162cd
--- /dev/null
+++ b/buildSrc/src/main/kotlin/cc/tweaked/gradle/SourceSetReference.kt
@@ -0,0 +1,20 @@
+package cc.tweaked.gradle
+
+import org.gradle.api.tasks.SourceSet
+
+data class SourceSetReference(
+    val sourceSet: SourceSet,
+    val classes: Boolean,
+    val external: Boolean,
+) {
+    companion object {
+        /** A source set in the current project. */
+        fun internal(sourceSet: SourceSet) = SourceSetReference(sourceSet, classes = true, external = false)
+
+        /** A source set from another project. */
+        fun external(sourceSet: SourceSet) = SourceSetReference(sourceSet, classes = true, external = true)
+
+        /** A source set which is inlined into the current project. */
+        fun inline(sourceSet: SourceSet) = SourceSetReference(sourceSet, classes = false, external = false)
+    }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 0ebd7d478..df8a5b486 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -6,11 +6,20 @@ forge = "43.1.1"
 parchment = "2022.10.16"
 parchmentMc = "1.19.2"
 
+asm = "9.3"
 autoService = "1.0.1"
+checkerFramework = "3.12.0"
 cobalt = { strictly = "[0.5.8,0.6.0)", prefer = "0.5.8" }
+fastutil = "8.5.6"
+guava = "31.0.1-jre"
 jetbrainsAnnotations = "23.0.0"
+jsr305 = "3.0.2"
 kotlin = "1.7.10"
 kotlin-coroutines = "1.6.0"
+logback = "1.2.11"
+netty = { strictly = "[4.1.77.Final,5.0)", prefer = "4.1.77.Final" }
+nightConfig = "3.6.5"
+slf4j = "1.7.36"
 
 # Testing
 hamcrest = "2.2"
@@ -32,11 +41,18 @@ spotless = "6.8.0"
 taskTree = "2.1.0"
 
 [libraries]
+asm = { module = "org.ow2.asm:asm", version.ref = "asm" }
 autoService = { module = "com.google.auto.service:auto-service", version.ref = "autoService" }
+checkerFramework = { module = "org.checkerframework:checker-qual", version.ref = "checkerFramework" }
 cobalt = { module = "org.squiddev:Cobalt", version.ref = "cobalt" }
+fastutil = { module = "it.unimi.dsi:fastutil", version.ref = "fastutil" }
+guava = { module = "com.google.guava:guava", version.ref = "guava" }
 jetbrainsAnnotations = { module = "org.jetbrains:annotations", version.ref = "jetbrainsAnnotations" }
+jsr305 = { module = "com.google.code.findbugs:jsr305", version.ref = "jsr305" }
 kotlin-coroutines = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-core", version.ref = "kotlin-coroutines" }
 kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib-jdk8", version.ref = "kotlin" }
+netty-http = { module = "io.netty:netty-codec-http", version.ref = "netty" }
+slf4j = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 
 # Testing
 hamcrest = { module = "org.hamcrest:hamcrest", version.ref = "hamcrest" }
diff --git a/projects/core-api/build.gradle.kts b/projects/core-api/build.gradle.kts
new file mode 100644
index 000000000..919d98909
--- /dev/null
+++ b/projects/core-api/build.gradle.kts
@@ -0,0 +1,27 @@
+plugins {
+    id("cc-tweaked.java-convention")
+    id("cc-tweaked.publishing")
+    id("cc-tweaked")
+}
+
+java {
+    withJavadocJar()
+}
+
+// Due to the slightly circular nature of our API, add the main API jars to the javadoc classpath.
+val docApi by configurations.registering {
+    isTransitive = false
+}
+
+dependencies {
+    compileOnly(project(":mc-stubs"))
+    compileOnlyApi(libs.jsr305)
+    compileOnlyApi(libs.checkerFramework)
+
+    "docApi"(project(":"))
+}
+
+tasks.javadoc {
+    // Depend on
+    classpath += docApi
+}
diff --git a/src/main/java/dan200/computercraft/api/filesystem/FileAttributes.java b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/FileAttributes.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/filesystem/FileAttributes.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/filesystem/FileAttributes.java
diff --git a/src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java
similarity index 97%
rename from src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java
index 24632b9cf..2f8e21d05 100644
--- a/src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java
@@ -8,6 +8,7 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.io.IOException;
+import java.io.Serial;
 import java.util.Objects;
 
 /**
@@ -16,6 +17,7 @@
  * This may be thrown from a {@link IMount} or {@link IWritableMount} to give more information about a failure.
  */
 public class FileOperationException extends IOException {
+    @Serial
     private static final long serialVersionUID = -8809108200853029849L;
 
     private final String filename;
diff --git a/src/main/java/dan200/computercraft/api/filesystem/IFileSystem.java b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IFileSystem.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/filesystem/IFileSystem.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IFileSystem.java
diff --git a/src/main/java/dan200/computercraft/api/filesystem/IMount.java b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IMount.java
similarity index 88%
rename from src/main/java/dan200/computercraft/api/filesystem/IMount.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IMount.java
index d98f195c4..c1b5bf6f3 100644
--- a/src/main/java/dan200/computercraft/api/filesystem/IMount.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IMount.java
@@ -5,9 +5,7 @@
  */
 package dan200.computercraft.api.filesystem;
 
-import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.peripheral.IComputerAccess;
-import net.minecraft.world.level.Level;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
@@ -19,12 +17,9 @@
  * Represents a read only part of a virtual filesystem that can be mounted onto a computer using
  * {@link IComputerAccess#mount(String, IMount)}.
  * <p>
- * Ready made implementations of this interface can be created using
- * {@link ComputerCraftAPI#createSaveDirMount(Level, String, long)} or
- * {@link ComputerCraftAPI#createResourceMount(String, String)}, or you're free to implement it yourselves!
+ * Typically you will not need to implement this interface yourself, and can use the factory methods from the
+ * {@linkplain dan200.computercraft.api.ComputerCraftAPI the main ComputerCraft API}.
  *
- * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
- * @see ComputerCraftAPI#createResourceMount(String, String)
  * @see IComputerAccess#mount(String, IMount)
  * @see IWritableMount
  */
diff --git a/src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java
similarity index 91%
rename from src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java
index 7542702a7..618dd9ecd 100644
--- a/src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java
@@ -5,9 +5,7 @@
  */
 package dan200.computercraft.api.filesystem;
 
-import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.peripheral.IComputerAccess;
-import net.minecraft.world.level.Level;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
@@ -19,10 +17,9 @@
  * Represents a part of a virtual filesystem that can be mounted onto a computer using {@link IComputerAccess#mount(String, IMount)}
  * or {@link IComputerAccess#mountWritable(String, IWritableMount)}, that can also be written to.
  * <p>
- * Ready made implementations of this interface can be created using
- * {@link ComputerCraftAPI#createSaveDirMount(Level, String, long)}, or you're free to implement it yourselves!
+ * Typically you will not need to implement this interface yourself, and can use the factory methods from the
+ * {@linkplain dan200.computercraft.api.ComputerCraftAPI the main ComputerCraft API}.
  *
- * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
  * @see IComputerAccess#mount(String, IMount)
  * @see IComputerAccess#mountWritable(String, IWritableMount)
  * @see IMount
diff --git a/src/main/java/dan200/computercraft/api/lua/GenericSource.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/GenericSource.java
similarity index 58%
rename from src/main/java/dan200/computercraft/api/lua/GenericSource.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/GenericSource.java
index 32f7b1eda..2ebdd2197 100644
--- a/src/main/java/dan200/computercraft/api/lua/GenericSource.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/GenericSource.java
@@ -5,31 +5,26 @@
  */
 package dan200.computercraft.api.lua;
 
-import dan200.computercraft.api.ComputerCraftAPI;
-import dan200.computercraft.api.ForgeComputerCraftAPI;
+import dan200.computercraft.api.peripheral.GenericPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheral;
-import dan200.computercraft.api.peripheral.IPeripheralProvider;
-import dan200.computercraft.core.asm.LuaMethod;
 import net.minecraft.resources.ResourceLocation;
-import net.minecraftforge.common.capabilities.Capability;
-import net.minecraftforge.items.IItemHandler;
 
 import javax.annotation.Nonnull;
 
 /**
- * A generic source of {@link LuaMethod} functions.
+ * A generic source of {@link LuaFunction} functions.
  * <p>
  * Unlike normal objects ({@link IDynamicLuaObject} or {@link IPeripheral}), methods do not target this object but
  * instead are defined as {@code static} and accept their target as the first parameter. This allows you to inject
- * methods onto objects you do not own, as well as declaring methods for a specific "trait" (for instance, a
- * {@link Capability}).
+ * methods onto objects you do not own, as well as declaring methods for a specific "trait" (for instance, a Forge
+ * capability or Fabric block lookup interface).
  * <p>
- * Currently the "generic peripheral" system is incompatible with normal peripherals. Normal {@link IPeripheralProvider}
- * or {@link IPeripheral} implementations take priority. Tile entities which use this system are given a peripheral name
- * determined by their id, rather than any peripheral provider. This will hopefully change in the future, once a suitable
- * design has been established.
+ * Currently the "generic peripheral" system is incompatible with normal peripherals. Peripherals explicitly provided
+ * by capabilities/the block lookup API take priority. Block entities which use this system are given a peripheral name
+ * determined by their id, rather than any peripheral provider, though additional types may be provided by overriding
+ * {@link GenericPeripheral#getType()}.
  * <p>
- * For example, the main CC: Tweaked mod defines a generic source for inventories, which works on {@link IItemHandler}s:
+ * For example, the main CC: Tweaked mod defines a generic source for inventories, which works on {@code IItemHandler}s:
  *
  * <pre>{@code
  * public class InventoryMethods implements GenericSource {
@@ -42,9 +37,10 @@
  * }
  * }</pre>
  *
- * @see ComputerCraftAPI#registerGenericSource(GenericSource)
- * @see ForgeComputerCraftAPI#registerGenericCapability(Capability) New capabilities (those not built into Forge) must be
- * explicitly given to the generic peripheral system, as there is no way to enumerate all capabilities.
+ * @see dan200.computercraft.api.ComputerCraftAPI#registerGenericSource(GenericSource)
+ * @see dan200.computercraft.api.ForgeComputerCraftAPI#registerGenericCapability New capabilities (those not
+ * built into Forge) must be explicitly given to the generic peripheral system, as there is no way to enumerate all
+ * capabilities.
  */
 public interface GenericSource {
     /**
diff --git a/src/main/java/dan200/computercraft/api/lua/IArguments.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/IArguments.java
similarity index 99%
rename from src/main/java/dan200/computercraft/api/lua/IArguments.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/IArguments.java
index 10dea4627..5c00b099a 100644
--- a/src/main/java/dan200/computercraft/api/lua/IArguments.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/IArguments.java
@@ -11,8 +11,6 @@
 import java.util.Map;
 import java.util.Optional;
 
-import static dan200.computercraft.api.lua.LuaValues.checkFinite;
-
 /**
  * The arguments passed to a function.
  */
@@ -102,7 +100,7 @@ default long getLong(int index) throws LuaException {
      * @throws LuaException If the value is not finite.
      */
     default double getFiniteDouble(int index) throws LuaException {
-        return checkFinite(index, getDouble(index));
+        return LuaValues.checkFinite(index, getDouble(index));
     }
 
     /**
diff --git a/src/main/java/dan200/computercraft/api/lua/IComputerSystem.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/IComputerSystem.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/IComputerSystem.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/IComputerSystem.java
diff --git a/src/main/java/dan200/computercraft/api/lua/IDynamicLuaObject.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/IDynamicLuaObject.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/IDynamicLuaObject.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/IDynamicLuaObject.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaAPI.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPI.java
similarity index 91%
rename from src/main/java/dan200/computercraft/api/lua/ILuaAPI.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPI.java
index ed08183a2..fb9905297 100644
--- a/src/main/java/dan200/computercraft/api/lua/ILuaAPI.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPI.java
@@ -5,8 +5,6 @@
  */
 package dan200.computercraft.api.lua;
 
-import dan200.computercraft.api.ComputerCraftAPI;
-
 /**
  * Represents a Lua object which is stored as a global variable on computer startup. This must either provide
  * {@link LuaFunction} annotated functions or implement {@link IDynamicLuaObject}.
@@ -14,8 +12,7 @@
  * Before implementing this interface, consider alternative methods of providing methods. It is generally preferred
  * to use peripherals to provide functionality to users.
  *
- * @see ILuaAPIFactory
- * @see ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
+ * @see ILuaAPIFactory For providing custom APIs to computers.
  */
 public interface ILuaAPI {
     /**
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java
similarity index 87%
rename from src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java
index 503ec6949..ea29e03eb 100644
--- a/src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java
@@ -5,8 +5,6 @@
  */
 package dan200.computercraft.api.lua;
 
-import dan200.computercraft.api.ComputerCraftAPI;
-
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -14,7 +12,7 @@
  * Construct an {@link ILuaAPI} for a specific computer.
  *
  * @see ILuaAPI
- * @see ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
+ * @see dan200.computercraft.api.ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
  */
 @FunctionalInterface
 public interface ILuaAPIFactory {
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaCallback.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaCallback.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/ILuaCallback.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaCallback.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaContext.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaContext.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/ILuaContext.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaContext.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaFunction.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaFunction.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/ILuaFunction.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaFunction.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ILuaTask.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaTask.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/ILuaTask.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ILuaTask.java
diff --git a/src/main/java/dan200/computercraft/api/lua/LuaException.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaException.java
similarity index 97%
rename from src/main/java/dan200/computercraft/api/lua/LuaException.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaException.java
index 1bd62c025..5b588b4ba 100644
--- a/src/main/java/dan200/computercraft/api/lua/LuaException.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaException.java
@@ -6,11 +6,13 @@
 package dan200.computercraft.api.lua;
 
 import javax.annotation.Nullable;
+import java.io.Serial;
 
 /**
  * An exception representing an error in Lua, like that raised by the {@code error()} function.
  */
 public class LuaException extends Exception {
+    @Serial
     private static final long serialVersionUID = -6136063076818512651L;
     private final boolean hasLevel;
     private final int level;
diff --git a/src/main/java/dan200/computercraft/api/lua/LuaFunction.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaFunction.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/LuaFunction.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaFunction.java
diff --git a/src/main/java/dan200/computercraft/api/lua/LuaTable.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaTable.java
similarity index 91%
rename from src/main/java/dan200/computercraft/api/lua/LuaTable.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaTable.java
index 82a80c316..2833acb35 100644
--- a/src/main/java/dan200/computercraft/api/lua/LuaTable.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaTable.java
@@ -11,6 +11,13 @@
 
 import static dan200.computercraft.api.lua.LuaValues.*;
 
+/**
+ * A view of a Lua table, which may be able to access table elements in a more optimised manner than
+ * {@link IArguments#getTable(int)}.
+ *
+ * @param <K> The type of keys in a table, will typically be a wildcard.
+ * @param <V> The type of values in a table, will typically be a wildcard.
+ */
 public interface LuaTable<K, V> extends Map<K, V> {
     /**
      * Compute the length of the array part of this table.
@@ -77,7 +84,6 @@ default int getInt(String key) throws LuaException {
         return (int) getLong(key);
     }
 
-
     @Nullable
     @Override
     default V put(K o, V o2) {
diff --git a/src/main/java/dan200/computercraft/api/lua/LuaValues.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaValues.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/LuaValues.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/LuaValues.java
diff --git a/src/main/java/dan200/computercraft/api/lua/MethodResult.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/MethodResult.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/MethodResult.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/MethodResult.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ObjectArguments.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ObjectArguments.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/ObjectArguments.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ObjectArguments.java
diff --git a/src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java
similarity index 94%
rename from src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java
index 1d39ee958..52e4a9753 100644
--- a/src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/lua/ObjectLuaTable.java
@@ -11,6 +11,9 @@
 import java.util.Map;
 import java.util.Set;
 
+/**
+ * An implementation of {@link LuaTable} based on a standard Java {@link Map}.
+ */
 public class ObjectLuaTable implements LuaTable<Object, Object> {
     private final Map<Object, Object> map;
 
diff --git a/src/main/java/dan200/computercraft/api/lua/TaskCallback.java b/projects/core-api/src/main/java/dan200/computercraft/api/lua/TaskCallback.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/lua/TaskCallback.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/lua/TaskCallback.java
diff --git a/src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java
similarity index 84%
rename from src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java
index 31b3f9f9e..1e0531230 100644
--- a/src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/GenericPeripheral.java
@@ -6,8 +6,6 @@
 package dan200.computercraft.api.peripheral;
 
 import dan200.computercraft.api.lua.GenericSource;
-import net.minecraft.world.level.block.entity.BlockEntity;
-import net.minecraftforge.items.IItemHandler;
 
 import javax.annotation.Nonnull;
 
@@ -15,14 +13,14 @@
  * A {@link GenericSource} which provides methods for a peripheral.
  * <p>
  * Unlike a {@link GenericSource}, all methods <strong>should</strong> target the same type, for instance a
- * {@link BlockEntity} subclass or a capability interface. This is not currently enforced.
+ * block entity subclass. This is not currently enforced.
  */
 public interface GenericPeripheral extends GenericSource {
     /**
      * Get the type of the exposed peripheral.
      * <p>
      * Unlike normal {@link IPeripheral}s, {@link GenericPeripheral} do not have to have a type. By default, the
-     * resulting peripheral uses the resource name of the wrapped {@link BlockEntity} (for instance {@code minecraft:chest}).
+     * resulting peripheral uses the resource name of the wrapped block entity (for instance {@code minecraft:chest}).
      * <p>
      * However, in some cases it may be more appropriate to specify a more readable name. Overriding this method allows
      * you to do so.
@@ -31,7 +29,7 @@ public interface GenericPeripheral extends GenericSource {
      * lexicographically smallest will be chosen. In order to avoid this conflict, this method should only be
      * implemented when your peripheral targets a single tile entity <strong>AND</strong> it's likely that you're the
      * only mod to do so. Similarly this should <strong>NOT</strong> be implemented when your methods target a
-     * capability or other interface (i.e. {@link IItemHandler}).
+     * capability or other interface (such as Forge's {@code IItemHandler}).
      *
      * @return The type of this peripheral or {@link PeripheralType#untyped()}.
      * @see IPeripheral#getType()
diff --git a/src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java
similarity index 94%
rename from src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java
index b306bedc5..5c8a0ac05 100644
--- a/src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java
@@ -5,14 +5,12 @@
  */
 package dan200.computercraft.api.peripheral;
 
-import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.lua.ILuaCallback;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.ILuaTask;
 import dan200.computercraft.api.lua.MethodResult;
-import net.minecraft.world.level.Level;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -32,8 +30,6 @@ public interface IComputerAccess {
      * @return The location on the computer's file system where you the mount mounted, or {@code null} if there was already a
      * file in the desired location. Store this value if you wish to unmount the mount later.
      * @throws NotAttachedException If the peripheral has been detached.
-     * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
-     * @see ComputerCraftAPI#createResourceMount(String, String)
      * @see #mount(String, IMount, String)
      * @see #mountWritable(String, IWritableMount)
      * @see #unmount(String)
@@ -53,8 +49,6 @@ default String mount(@Nonnull String desiredLocation, @Nonnull IMount mount) {
      * @return The location on the computer's file system where you the mount mounted, or {@code null} if there was already a
      * file in the desired location. Store this value if you wish to unmount the mount later.
      * @throws NotAttachedException If the peripheral has been detached.
-     * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
-     * @see ComputerCraftAPI#createResourceMount(String, String)
      * @see #mount(String, IMount)
      * @see #mountWritable(String, IWritableMount)
      * @see #unmount(String)
@@ -71,8 +65,6 @@ default String mount(@Nonnull String desiredLocation, @Nonnull IMount mount) {
      * @return The location on the computer's file system where you the mount mounted, or null if there was already a
      * file in the desired location. Store this value if you wish to unmount the mount later.
      * @throws NotAttachedException If the peripheral has been detached.
-     * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
-     * @see ComputerCraftAPI#createResourceMount(String, String)
      * @see #mount(String, IMount)
      * @see #unmount(String)
      * @see IMount
@@ -91,8 +83,6 @@ default String mountWritable(@Nonnull String desiredLocation, @Nonnull IWritable
      * @return The location on the computer's file system where you the mount mounted, or null if there was already a
      * file in the desired location. Store this value if you wish to unmount the mount later.
      * @throws NotAttachedException If the peripheral has been detached.
-     * @see ComputerCraftAPI#createSaveDirMount(Level, String, long)
-     * @see ComputerCraftAPI#createResourceMount(String, String)
      * @see #mount(String, IMount)
      * @see #unmount(String)
      * @see IMount
diff --git a/src/main/java/dan200/computercraft/api/peripheral/IDynamicPeripheral.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IDynamicPeripheral.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/peripheral/IDynamicPeripheral.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IDynamicPeripheral.java
diff --git a/src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java
similarity index 93%
rename from src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java
index f129b3a83..83b867e0a 100644
--- a/src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java
@@ -6,7 +6,6 @@
 package dan200.computercraft.api.peripheral;
 
 import dan200.computercraft.api.lua.LuaFunction;
-import net.minecraftforge.common.capabilities.Capability;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -16,8 +15,8 @@
 /**
  * The interface that defines a peripheral.
  * <p>
- * In order to expose a peripheral for your block or tile entity, you may either attach a {@link Capability}, or
- * register a {@link IPeripheralProvider}. This <em>cannot</em> be implemented {@link IPeripheral} directly on the tile.
+ * In order to expose a peripheral for your block or block entity, you should either attach a capability (Forge) or
+ * use the block lookup API (Fabric). This interface <em>cannot</em> be implemented directly on the block entity.
  * <p>
  * Peripherals should provide a series of methods to the user, either using {@link LuaFunction} or by implementing
  * {@link IDynamicPeripheral}.
diff --git a/src/main/java/dan200/computercraft/api/peripheral/IWorkMonitor.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IWorkMonitor.java
similarity index 100%
rename from src/main/java/dan200/computercraft/api/peripheral/IWorkMonitor.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/IWorkMonitor.java
diff --git a/src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java
similarity index 95%
rename from src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java
index c36d84ebd..cc3748e38 100644
--- a/src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/NotAttachedException.java
@@ -5,11 +5,14 @@
  */
 package dan200.computercraft.api.peripheral;
 
+import java.io.Serial;
+
 /**
  * Thrown when performing operations on {@link IComputerAccess} when the current peripheral is no longer attached to
  * the computer.
  */
 public class NotAttachedException extends IllegalStateException {
+    @Serial
     private static final long serialVersionUID = 1221244785535553536L;
 
     public NotAttachedException() {
diff --git a/src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java
similarity index 78%
rename from src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java
rename to projects/core-api/src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java
index 5bf80b644..0792c95f6 100644
--- a/src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java
+++ b/projects/core-api/src/main/java/dan200/computercraft/api/peripheral/PeripheralType.java
@@ -5,9 +5,6 @@
  */
 package dan200.computercraft.api.peripheral;
 
-import com.google.common.base.Strings;
-import com.google.common.collect.ImmutableSet;
-
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Collection;
@@ -29,8 +26,8 @@ public final class PeripheralType {
     public PeripheralType(String type, Set<String> additionalTypes) {
         this.type = type;
         this.additionalTypes = additionalTypes;
-        if (additionalTypes.contains(null)) {
-            throw new IllegalArgumentException("All additional types must be non-null");
+        for (var item : additionalTypes) {
+            if (item == null) throw new NullPointerException("All additional types must be non-null");
         }
     }
 
@@ -50,7 +47,7 @@ public static PeripheralType untyped() {
      * @return The constructed peripheral type.
      */
     public static PeripheralType ofType(@Nonnull String type) {
-        if (Strings.isNullOrEmpty(type)) throw new IllegalArgumentException("type cannot be null or empty");
+        checkTypeName("type cannot be null or empty");
         return new PeripheralType(type, Collections.emptySet());
     }
 
@@ -62,8 +59,8 @@ public static PeripheralType ofType(@Nonnull String type) {
      * @return The constructed peripheral type.
      */
     public static PeripheralType ofType(@Nonnull String type, Collection<String> additionalTypes) {
-        if (Strings.isNullOrEmpty(type)) throw new IllegalArgumentException("type cannot be null or empty");
-        return new PeripheralType(type, ImmutableSet.copyOf(additionalTypes));
+        checkTypeName("type cannot be null or empty");
+        return new PeripheralType(type, getTypes(additionalTypes));
     }
 
     /**
@@ -74,8 +71,8 @@ public static PeripheralType ofType(@Nonnull String type, Collection<String> add
      * @return The constructed peripheral type.
      */
     public static PeripheralType ofType(@Nonnull String type, @Nonnull String... additionalTypes) {
-        if (Strings.isNullOrEmpty(type)) throw new IllegalArgumentException("type cannot be null or empty");
-        return new PeripheralType(type, ImmutableSet.copyOf(additionalTypes));
+        checkTypeName(type);
+        return new PeripheralType(type, Set.of(additionalTypes));
     }
 
     /**
@@ -85,7 +82,7 @@ public static PeripheralType ofType(@Nonnull String type, @Nonnull String... add
      * @return The constructed peripheral type.
      */
     public static PeripheralType ofAdditional(Collection<String> additionalTypes) {
-        return new PeripheralType(null, ImmutableSet.copyOf(additionalTypes));
+        return new PeripheralType(null, getTypes(additionalTypes));
     }
 
     /**
@@ -95,7 +92,7 @@ public static PeripheralType ofAdditional(Collection<String> additionalTypes) {
      * @return The constructed peripheral type.
      */
     public static PeripheralType ofAdditional(@Nonnull String... additionalTypes) {
-        return new PeripheralType(null, ImmutableSet.copyOf(additionalTypes));
+        return new PeripheralType(null, Set.of(additionalTypes));
     }
 
     /**
@@ -117,4 +114,14 @@ public String getPrimaryType() {
     public Set<String> getAdditionalTypes() {
         return additionalTypes;
     }
+
+    private static void checkTypeName(@Nullable String type) {
+        if (type == null || type.isEmpty()) throw new IllegalArgumentException("type cannot be null or empty");
+    }
+
+    private static Set<String> getTypes(Collection<String> types) {
+        if (types.isEmpty()) return Collections.emptySet();
+        if (types.size() == 1) return Collections.singleton(types.iterator().next());
+        return Set.copyOf(types);
+    }
 }
diff --git a/projects/mc-stubs/build.gradle.kts b/projects/mc-stubs/build.gradle.kts
new file mode 100644
index 000000000..7dd63a3b1
--- /dev/null
+++ b/projects/mc-stubs/build.gradle.kts
@@ -0,0 +1,8 @@
+plugins {
+    id("cc-tweaked.java-convention")
+}
+
+// Skip checkstyle here, it's going to be deleted soon anyway!
+tasks.checkstyleMain {
+    enabled = false
+}
diff --git a/projects/mc-stubs/src/main/java/net/minecraft/resources/ResourceLocation.java b/projects/mc-stubs/src/main/java/net/minecraft/resources/ResourceLocation.java
new file mode 100644
index 000000000..b7697ab2c
--- /dev/null
+++ b/projects/mc-stubs/src/main/java/net/minecraft/resources/ResourceLocation.java
@@ -0,0 +1,14 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2022. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+package net.minecraft.resources;
+
+/**
+ * Placeholder class so we can preserve API compatibility for this release.
+ */
+public final class ResourceLocation {
+    private ResourceLocation() {
+    }
+}
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 998bf3e4c..0adfc4d4e 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -15,3 +15,10 @@ pluginManagement {
 
 val mcVersion: String by settings
 rootProject.name = "cc-tweaked-$mcVersion"
+
+include(":mc-stubs")
+include(":core-api")
+
+for (project in rootProject.children) {
+    project.projectDir = file("projects/${project.name}")
+}
diff --git a/src/main/java/dan200/computercraft/core/apis/FastLuaException.java b/src/main/java/dan200/computercraft/core/apis/FastLuaException.java
index b983028d9..b7f2d21da 100644
--- a/src/main/java/dan200/computercraft/core/apis/FastLuaException.java
+++ b/src/main/java/dan200/computercraft/core/apis/FastLuaException.java
@@ -8,11 +8,13 @@
 import dan200.computercraft.api.lua.LuaException;
 
 import javax.annotation.Nullable;
+import java.io.Serial;
 
 /**
  * A Lua exception which does not contain its stack trace.
  */
 public class FastLuaException extends LuaException {
+    @Serial
     private static final long serialVersionUID = 5957864899303561143L;
 
     public FastLuaException(@Nullable String message) {
diff --git a/src/main/java/dan200/computercraft/core/apis/http/HTTPRequestException.java b/src/main/java/dan200/computercraft/core/apis/http/HTTPRequestException.java
index 837e8585d..ca544c8ed 100644
--- a/src/main/java/dan200/computercraft/core/apis/http/HTTPRequestException.java
+++ b/src/main/java/dan200/computercraft/core/apis/http/HTTPRequestException.java
@@ -5,7 +5,10 @@
  */
 package dan200.computercraft.core.apis.http;
 
+import java.io.Serial;
+
 public class HTTPRequestException extends Exception {
+    @Serial
     private static final long serialVersionUID = 7591208619422744652L;
 
     public HTTPRequestException(String s) {
diff --git a/src/main/java/dan200/computercraft/core/filesystem/FileSystemException.java b/src/main/java/dan200/computercraft/core/filesystem/FileSystemException.java
index cf50bffe6..37bbd976f 100644
--- a/src/main/java/dan200/computercraft/core/filesystem/FileSystemException.java
+++ b/src/main/java/dan200/computercraft/core/filesystem/FileSystemException.java
@@ -5,7 +5,10 @@
  */
 package dan200.computercraft.core.filesystem;
 
+import java.io.Serial;
+
 public class FileSystemException extends Exception {
+    @Serial
     private static final long serialVersionUID = -2500631644868104029L;
 
     FileSystemException(String s) {
diff --git a/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java b/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
index 5824c79a5..faab9f49d 100644
--- a/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
+++ b/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java
@@ -30,6 +30,7 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.io.InputStream;
+import java.io.Serial;
 import java.nio.ByteBuffer;
 import java.util.*;
 import java.util.concurrent.SynchronousQueue;
@@ -444,6 +445,7 @@ private void handlePause(DebugState ds, DebugFrame di) throws LuaError, UnwindTh
     }
 
     private static final class HardAbortError extends Error {
+        @Serial
         private static final long serialVersionUID = 7954092008586367501L;
 
         static final HardAbortError INSTANCE = new HardAbortError();
diff --git a/src/main/java/dan200/computercraft/impl/ServiceException.java b/src/main/java/dan200/computercraft/impl/ServiceException.java
index 6db2f7a1c..fa97dea8c 100644
--- a/src/main/java/dan200/computercraft/impl/ServiceException.java
+++ b/src/main/java/dan200/computercraft/impl/ServiceException.java
@@ -8,6 +8,7 @@
 import org.jetbrains.annotations.ApiStatus;
 
 import javax.annotation.Nullable;
+import java.io.Serial;
 
 /**
  * A ComputerCraft-related service failed to load.
@@ -16,6 +17,7 @@
  */
 @ApiStatus.Internal
 class ServiceException extends RuntimeException {
+    @Serial
     private static final long serialVersionUID = -8392300691666423882L;
 
     ServiceException(String message, @Nullable Throwable cause) {