diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 530c3f38fc..e6774b1759 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -4,7 +4,7 @@ jobs:
   build:
     strategy:
       matrix:
-        java: [17-jdk, 18-jdk]
+        java: [17-jdk, 20-jdk]
     runs-on: ubuntu-22.04
     container:
       image: eclipse-temurin:${{ matrix.java }}
@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v3
       - run: ./gradlew build javadocJar checkMappings --stacktrace --warning-mode fail
       - name: Build artifacts
-        if: ${{ matrix.java == '18-jdk' }}
+        if: ${{ matrix.java == '20-jdk' }}
         continue-on-error: true
         uses: actions/upload-artifact@v3
         with:
@@ -23,7 +23,7 @@ jobs:
   test-build-logic:
     runs-on: ubuntu-22.04
     container:
-      image: eclipse-temurin:18-jdk
+      image: eclipse-temurin:20-jdk
       options: --user root
     steps:
       - uses: actions/checkout@v3
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 8d64a974ce..6c114d697f 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -6,7 +6,7 @@ jobs:
     if: ${{ github.repository_owner == 'FabricMC' }}
     runs-on: ubuntu-22.04
     container:
-      image: eclipse-temurin:18-jdk
+      image: eclipse-temurin:20-jdk
       options: --user root
     steps:
       - uses: actions/checkout@v3
diff --git a/.github/workflows/release-filament.yml b/.github/workflows/release-filament.yml
index bd1da0bf25..7396c3e780 100644
--- a/.github/workflows/release-filament.yml
+++ b/.github/workflows/release-filament.yml
@@ -4,7 +4,7 @@ jobs:
   build:
     runs-on: ubuntu-22.04
     container:
-      image: eclipse-temurin:18-jdk
+      image: eclipse-temurin:20-jdk
       options: --user root
     steps:
       - uses: actions/checkout@v3
diff --git a/build.gradle b/build.gradle
index bf704fe6ae..3ee0b98816 100644
--- a/build.gradle
+++ b/build.gradle
@@ -9,7 +9,6 @@ buildscript {
 	}
 	dependencies {
 		classpath "cuchaz:enigma-cli:${project.enigma_version}"
-		classpath "net.fabricmc:stitch:${project.stitch_version}"
 		classpath "net.fabricmc:name-proposal:${project.name_proposal_version}"
 	}
 }
@@ -100,72 +99,26 @@ def minecraftLibraries = configurations.minecraftLibraries
 import cuchaz.enigma.command.CheckMappingsCommand
 import net.fabricmc.filament.task.MapJarTask
 import net.fabricmc.filament.task.DownloadTask
-import net.fabricmc.filament.task.ExtractZipEntryTask
 import net.fabricmc.filament.task.UnpickJarTask
 import net.fabricmc.filament.task.base.WithFileInput
 import net.fabricmc.filament.task.base.WithFileOutput
-import net.fabricmc.filament.task.enigma.ConvertMappingsTask
 import net.fabricmc.filament.task.enigma.MapSpecializedMethodsTask
-import net.fabricmc.stitch.commands.CommandMergeTiny
-import net.fabricmc.stitch.commands.CommandReorderTiny
-import net.fabricmc.stitch.commands.tinyv2.CommandMergeTinyV2
-import net.fabricmc.stitch.commands.tinyv2.CommandReorderTinyV2
+import net.fabricmc.filament.task.mappingio.ConvertMappingsTask
+import net.fabricmc.filament.task.mappingio.MergeMappingsTask
+import net.fabricmc.mappingio.format.MappingFormat
 import net.fabricmc.nameproposal.MappingNameCompleter
 import org.gradle.work.DisableCachingByDefault
 
 import java.util.zip.GZIPOutputStream
 
-task downloadIntermediary(type: DownloadTask) {
+tasks.register('downloadIntermediary', DownloadTask) {
 	group = buildMappingGroup
 	url = "https://github.com/FabricMC/intermediary/raw/master/mappings/${minecraft_version}.tiny"
 	output = new File(cacheFilesMinecraft, "${minecraft_version}-intermediary.tiny")
 }
 
-task downloadIntermediaryV2(type: DownloadTask) {
-	group = buildMappingGroup
-	url = "https://maven.fabricmc.net/net/fabricmc/intermediary/${minecraft_version}/intermediary-${minecraft_version}-v2.jar"
-	output = new File(cacheFilesMinecraft, "${minecraft_version}-intermediary-v2.jar")
-}
-
-task extractIntermediaryV2(type: ExtractZipEntryTask) {
-	input = downloadIntermediaryV2.output
-	output = new File(cacheFilesMinecraft, "${minecraft_version}-intermediary-v2.tiny")
-	entry = "mappings/mappings.tiny"
-}
-
-task invertIntermediary(dependsOn: downloadIntermediary, type: FileInputOutput) {
-	group = buildMappingGroup
-	input = downloadIntermediary.output
-	output = new File(cacheFilesMinecraft, "${minecraft_version}-intermediary-inverted.tiny")
-
-	doLast {
-		String[] v1Args = [
-				inputFile.getAbsolutePath(),
-				outputFile.getAbsolutePath(),
-				"intermediary", "official"
-		]
-
-		new CommandReorderTiny().run(v1Args)
-	}
-}
-
-task invertIntermediaryv2(dependsOn: [downloadIntermediaryV2, extractIntermediaryV2], type: FileInputOutput) {
-	group = buildMappingGroup
-	output = new File(cacheFilesMinecraft, "${minecraft_version}-intermediary-inverted-v2.tiny")
-	input = extractIntermediaryV2.output
-
-	doLast {
-		String[] v2Args = [
-				inputFile.getAbsolutePath(),
-				outputFile.getAbsolutePath(),
-				"intermediary", "official"
-		]
-
-		new CommandReorderTinyV2().run(v2Args)
-	}
-}
-
-task mapIntermediaryJar(type: MapJarTask, dependsOn: [downloadIntermediary, mergeMinecraftJars]) {
+tasks.register('mapIntermediaryJar', MapJarTask) {
+	dependsOn downloadIntermediary, mergeMinecraftJars
 	group = mapJarGroup
 	output = file("${minecraft_version}-intermediary.jar")
 	input = mergeMinecraftJars.output
@@ -175,7 +128,8 @@ task mapIntermediaryJar(type: MapJarTask, dependsOn: [downloadIntermediary, merg
 	to = 'intermediary'
 }
 
-task mapServerIntermediaryJar(type: MapJarTask, dependsOn: [downloadIntermediary, extractBundledServer]) {
+tasks.register('mapServerIntermediaryJar', MapJarTask) {
+	dependsOn downloadIntermediary, extractBundledServer
 	group = mapJarGroup
 	output = file("${minecraft_version}-server-intermediary.jar")
 	input = extractBundledServer.output
@@ -185,19 +139,20 @@ task mapServerIntermediaryJar(type: MapJarTask, dependsOn: [downloadIntermediary
 	to = 'intermediary'
 }
 
-task yarn(dependsOn: mapIntermediaryJar, type: EnigmaTask) {
+tasks.register('yarn', EnigmaTask) {
+	dependsOn mapIntermediaryJar
 	group = yarnGroup
 	jar = mapIntermediaryJar.output
 	mappings = mappingsDir
 }
 
-task yarnCommon(type: EnigmaTask) {
+tasks.register('yarnCommon', EnigmaTask) {
 	group = yarnGroup
 	jar = mapServerIntermediaryJar.output
 	mappings = mappingsDir
 }
 
-task checkMappings() {
+tasks.register('checkMappings') {
 	group = buildMappingGroup
 	inputs.dir mappingsDir
 	inputs.file mapIntermediaryJar.output
@@ -206,8 +161,8 @@ task checkMappings() {
 
 	doLast {
 		String[] args = [
-				intermediaryJarPath,
-				mappingsDir.getAbsolutePath()
+			intermediaryJarPath,
+			mappingsDir.getAbsolutePath()
 		]
 
 		try {
@@ -218,7 +173,7 @@ task checkMappings() {
 	}
 }
 
-task mapSpecializedMethods(type: MapSpecializedMethodsTask) {
+tasks.register('mapSpecializedMethods', MapSpecializedMethodsTask) {
 	intermediaryJarFile = mapIntermediaryJar.output
 	mappings = mappingsDir
 	output = new File(tempDir, "yarn-mappings-v2.tiny")
@@ -227,48 +182,18 @@ task mapSpecializedMethods(type: MapSpecializedMethodsTask) {
 	outputMappingsFormat = "tinyv2:intermediary:named"
 }
 
-task convertToV1(type: ConvertMappingsTask) {
+tasks.register('convertToV1', ConvertMappingsTask) {
 	input = mapSpecializedMethods.output
 	output = new File(tempDir, "yarn-mappings.tiny")
-
-	inputMappingsFormat = "tinyv2"
-	outputMappingsFormat = "tiny:intermediary:named"
+	outputFormat = MappingFormat.TINY
 }
 
-task mergeTiny(dependsOn: ["convertToV1", "invertIntermediary"], type: FileOutput) {
+tasks.register('mergeTiny', MergeMappingsTask) {
 	group = buildMappingGroup
-
-	def unorderedResultMappings = new File(tempDir, "mappings-unordered.tiny")
-	outputs.file unorderedResultMappings
-
 	output = new File(tempDir, "mappings.tiny")
-
-	inputs.file convertToV1.output
-	inputs.file invertIntermediary.output
-
-	def intermediaryTinyPath = invertIntermediary.outputFile.absolutePath
-	def yarnTinyPath = convertToV1.outputFile.absolutePath
-	def outputPath = unorderedResultMappings.absolutePath
-
-	doLast {
-		String[] args = [
-				intermediaryTinyPath,
-				yarnTinyPath,
-				outputPath,
-				"intermediary",
-				"official"
-		]
-
-		new CommandMergeTiny().run(args)
-
-		String[] args2 = [
-				unorderedResultMappings.getAbsolutePath(),
-				output.getAbsolutePath(),
-				"official", "intermediary", "named"
-		]
-
-		new CommandReorderTiny().run(args2)
-	}
+	mappingInputs.from downloadIntermediary.output
+	mappingInputs.from convertToV1.output
+	outputFormat = MappingFormat.TINY
 }
 
 // Disable the default jar task
@@ -276,7 +201,8 @@ jar {
 	enabled = false
 }
 
-task tinyJar(type: Jar, dependsOn: mergeTiny) {
+tasks.register('tinyJar', Jar) {
+	dependsOn mergeTiny
 	group = buildMappingGroup
 	archiveFileName = "yarn-${yarnVersion}.jar"
 	destinationDirectory.set(file("build/libs"))
@@ -290,7 +216,8 @@ task tinyJar(type: Jar, dependsOn: mergeTiny) {
 	}
 }
 
-task compressTiny(dependsOn: [tinyJar, mergeTiny], type: FileInputOutput) {
+tasks.register('compressTiny', FileInputOutput) {
+	dependsOn tinyJar, mergeTiny
 	group = buildMappingGroup
 
 	input = mergeTiny.output
@@ -322,7 +249,7 @@ sourceSets {
 	packageDocs // package info files
 }
 
-task constantsJar(type: Jar) {
+tasks.register('constantsJar', Jar) {
 	from sourceSets.constants.output
 	archiveClassifier = "constants"
 }
@@ -355,7 +282,8 @@ spotless {
 	}
 }
 
-task sourcesJar(type: Jar, dependsOn: classes) {
+tasks.register('sourcesJar', Jar) {
+	dependsOn classes
 	archiveClassifier = "sources"
 	from sourceSets.constants.allSource
 }
@@ -364,7 +292,8 @@ task sourcesJar(type: Jar, dependsOn: classes) {
 
 build.dependsOn constantsJar
 
-task insertAutoGeneratedEnumMappings(dependsOn : [mapIntermediaryJar, downloadIntermediary], type : FileInputOutput){
+tasks.register('insertAutoGeneratedEnumMappings', FileInputOutput) {
+	dependsOn mapIntermediaryJar, downloadIntermediary
 	group = buildMappingGroup
 	input = mapSpecializedMethods.output
 	output = new File(tempDir, "unmerged-named-v2-with-enum.tiny")
@@ -377,10 +306,10 @@ task insertAutoGeneratedEnumMappings(dependsOn : [mapIntermediaryJar, downloadIn
 
 	doLast {
 		MappingNameCompleter.completeNames(
-				intermediaryJarPath,
-				inputPath,
-				intermediaryMappingsPath,
-				outputPath
+			intermediaryJarPath,
+			inputPath,
+			intermediaryMappingsPath,
+			outputPath
 		)
 	}
 }
@@ -391,7 +320,7 @@ remapUnpickDefinitionsIntermediary {
 	mappings = insertAutoGeneratedEnumMappings.output
 }
 
-task unpickIntermediaryJar(type: UnpickJarTask) {
+tasks.register('unpickIntermediaryJar', UnpickJarTask) {
 	group = 'unpick'
 	input = mapIntermediaryJar.output
 	output = file("${minecraft_version}-intermediary-unpicked.jar")
@@ -400,48 +329,23 @@ task unpickIntermediaryJar(type: UnpickJarTask) {
 	classpath.from minecraftLibraries
 }
 
-task yarnUnpicked(dependsOn: "unpickIntermediaryJar", type: EnigmaTask) {
+tasks.register('yarnUnpicked', EnigmaTask) {
+	dependsOn "unpickIntermediaryJar"
 	group = yarnGroup
 	jar = unpickIntermediaryJar.output
 	mappings = mappingsDir
 }
 
-task mergeV2(dependsOn: ["v2UnmergedYarnJar"], type: FileOutput) {
-	def mergedV2 = new File(tempDir, "merged-v2.tiny");
-	outputs.file mergedV2
-
-	output = new File(tempDir, "merged-reordered-v2.tiny")
-
-	inputs.file insertAutoGeneratedEnumMappings.output
-	inputs.file invertIntermediaryv2.output
-
-	def intermediaryPath = invertIntermediaryv2.outputFile.absolutePath
-	def mappingsPath = insertAutoGeneratedEnumMappings.outputFile.absolutePath
-
-	doLast {
-		String[] args = [
-				intermediaryPath,
-				mappingsPath,
-				mergedV2.getAbsolutePath(),
-				"intermediary",
-				"official"
-		]
-
-		new CommandMergeTinyV2().run(args)
-
-		//Reorder the mappings to match the output of loom
-		args = [
-				mergedV2.getAbsolutePath(),
-				output.getAbsolutePath(),
-				"official",
-				"intermediary",
-				"named"
-		]
-		new CommandReorderTinyV2().run(args)
-	}
+tasks.register('mergeV2', MergeMappingsTask) {
+	group = buildMappingGroup
+	output = new File(tempDir, "merged-v2.tiny")
+	mappingInputs.from downloadIntermediary.output
+	mappingInputs.from insertAutoGeneratedEnumMappings.output
+	outputFormat = MappingFormat.TINY_2
 }
 
-task v2UnmergedYarnJar(dependsOn: [insertAutoGeneratedEnumMappings, combineUnpickDefinitions], type: Jar) {
+tasks.register('v2UnmergedYarnJar', Jar) {
+	dependsOn insertAutoGeneratedEnumMappings, combineUnpickDefinitions
 	def mappings = insertAutoGeneratedEnumMappings.output
 	group = "mapping build"
 	archiveFileName = "yarn-${yarnVersion}-v2.jar"
@@ -452,7 +356,7 @@ task v2UnmergedYarnJar(dependsOn: [insertAutoGeneratedEnumMappings, combineUnpic
 	from(combineUnpickDefinitions.output) {
 		rename combineUnpickDefinitions.output.get().asFile.name, "extras/definitions.unpick"
 	}
-	from (file(unpickMetaFile)) {
+	from(file(unpickMetaFile)) {
 		expand version: project.unpick_version
 		rename unpickMetaFile.name, "extras/unpick.json"
 	}
@@ -462,8 +366,9 @@ task v2UnmergedYarnJar(dependsOn: [insertAutoGeneratedEnumMappings, combineUnpic
 	}
 }
 
-task v2MergedYarnJar(dependsOn: ["mergeV2"], type: Jar) {
-	def mappings = mergeV2.output
+tasks.register('v2MergedYarnJar', Jar) {
+	dependsOn mergeV2
+	def mappings = mergeV2.outputFile
 	group = "mapping build"
 	archiveFileName = "yarn-${yarnVersion}-mergedv2.jar"
 
@@ -473,7 +378,7 @@ task v2MergedYarnJar(dependsOn: ["mergeV2"], type: Jar) {
 	from(combineUnpickDefinitions.output) {
 		rename combineUnpickDefinitions.output.get().asFile.name, "extras/definitions.unpick"
 	}
-	from (file(unpickMetaFile)) {
+	from(file(unpickMetaFile)) {
 		expand version: project.unpick_version
 		rename unpickMetaFile.name, "extras/unpick.json"
 	}
@@ -483,7 +388,8 @@ task v2MergedYarnJar(dependsOn: ["mergeV2"], type: Jar) {
 	}
 }
 
-task mapNamedJar(type: MapJarTask, dependsOn: ["mergeV2", "unpickIntermediaryJar"]) {
+tasks.register('mapNamedJar', MapJarTask) {
+	dependsOn mergeV2, unpickIntermediaryJar
 	group = mapJarGroup
 	output = file("${minecraft_version}-named.jar")
 	input = unpickIntermediaryJar.output
@@ -492,22 +398,23 @@ task mapNamedJar(type: MapJarTask, dependsOn: ["mergeV2", "unpickIntermediaryJar
 	from = 'intermediary'
 	to = 'named'
 	classMappings = [
-			"javax/annotation/Nullable": "org/jetbrains/annotations/Nullable",
-			"javax/annotation/Nonnull": "org/jetbrains/annotations/NotNull",
-			"javax/annotation/concurrent/Immutable": "org/jetbrains/annotations/Unmodifiable"
+		"javax/annotation/Nullable"            : "org/jetbrains/annotations/Nullable",
+		"javax/annotation/Nonnull"             : "org/jetbrains/annotations/NotNull",
+		"javax/annotation/concurrent/Immutable": "org/jetbrains/annotations/Unmodifiable"
 	]
 }
 
 def mcLibsDir = file('build/tmp/mclibs')
 
 // Task to copy all the mc libs into a single directory.
-task syncDependencies(type: Sync) {
+tasks.register('syncDependencies', Sync) {
 	from minecraftLibraries
 	into mcLibsDir
 }
 
 def fakeSourceDir = file(".gradle/temp/fakeSource")
-task genFakeSource(type: JavaExec, dependsOn: ["mergeV2", "mapNamedJar", syncDependencies]) {
+tasks.register('genFakeSource', JavaExec) {
+	dependsOn mergeV2, mapNamedJar, syncDependencies
 	group = "javadoc generation"
 
 	inputs.file mergeV2.output
@@ -519,10 +426,11 @@ task genFakeSource(type: JavaExec, dependsOn: ["mergeV2", "mapNamedJar", syncDep
 	mainClass = "net.fabricmc.mappingpoet.Main"
 	classpath configurations.mappingPoet
 	// use merged v2 so we have all namespaces in jd
-	args mergeV2.output.getAbsolutePath(), mapNamedJar.outputFile.getAbsolutePath(), fakeSourceDir.getAbsolutePath(), mcLibsDir.getAbsolutePath()
+	args mergeV2.outputFile.getAbsolutePath(), mapNamedJar.outputFile.getAbsolutePath(), fakeSourceDir.getAbsolutePath(), mcLibsDir.getAbsolutePath()
 }
 
-task decompileCFR(type: JavaExec, dependsOn: [mapNamedJar]) {
+tasks.register('decompileCFR', JavaExec) {
+	dependsOn mapNamedJar
 	mainClass = "org.benf.cfr.reader.Main"
 
 	args mapNamedJar.outputFile.getAbsolutePath(), "--outputdir", file("namedSrc").absolutePath
@@ -618,7 +526,8 @@ javadoc {
 	}
 }
 
-task javadocJar(type: Jar, dependsOn: ["javadoc"]) {
+tasks.register('javadocJar', Jar) {
+	dependsOn javadoc
 	group = "javadoc generation"
 
 	from javadoc.destinationDir
@@ -680,7 +589,7 @@ publishing {
 }
 
 // A task to ensure that the version being released has not already been released.
-task checkVersion {
+tasks.register('checkVersion') {
 	doFirst {
 		def xml = new URL("https://maven.fabricmc.net/net/fabricmc/yarn/maven-metadata.xml").text
 		def metadata = new XmlSlurper().parseText(xml)
@@ -693,10 +602,6 @@ task checkVersion {
 
 publish.mustRunAfter checkVersion
 
-abstract class FileOutput extends DefaultTask {
-	@OutputFile
-	File output
-}
 
 abstract class FileInputOutput extends DefaultTask implements WithFileInput, WithFileOutput {
 }
diff --git a/filament/build.gradle b/filament/build.gradle
index 69c7295b7e..0b1840a463 100644
--- a/filament/build.gradle
+++ b/filament/build.gradle
@@ -24,6 +24,7 @@ repositories {
 		url 'https://maven.fabricmc.net'
 	}
 	mavenCentral()
+	mavenLocal()
 }
 
 dependencies {
@@ -34,20 +35,16 @@ dependencies {
 	implementation "net.fabricmc.unpick:unpick:$properties.unpick_version"
 	implementation "net.fabricmc.unpick:unpick-format-utils:$properties.unpick_version"
 	implementation "net.fabricmc.unpick:unpick-cli:$properties.unpick_version"
-	implementation "net.fabricmc:tiny-mappings-parser:$properties.tiny_mappings_parser_version"
 	implementation "net.fabricmc:tiny-remapper:$properties.tiny_remapper_version"
 	implementation "net.fabricmc:mappingpoet:$properties.mappingpoet_version"
 	implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.4.2'
+	implementation 'net.fabricmc:mapping-io:0.4.0'
 
 	// Contains a number of useful utilities we can re-use.
-	implementation ("net.fabricmc:fabric-loom:1.1.10") {
+	implementation ("net.fabricmc:fabric-loom:1.2.7") {
 		transitive = false
 	}
 
-	implementation ('net.fabricmc:stitch:0.6.2') {
-		exclude module: 'enigma'
-	}
-
 	testImplementation platform("org.junit:junit-bom:$properties.junit_version")
 	testImplementation 'org.junit.jupiter:junit-jupiter'
 	testImplementation "org.assertj:assertj-core:$properties.assertj_version"
diff --git a/filament/gradle.properties b/filament/gradle.properties
index caf6a2df1e..05a29bdf1a 100644
--- a/filament/gradle.properties
+++ b/filament/gradle.properties
@@ -1 +1 @@
-filament_version=0.5.0
\ No newline at end of file
+filament_version=0.6.0
\ No newline at end of file
diff --git a/filament/src/main/java/net/fabricmc/filament/task/ExtractZipEntryTask.java b/filament/src/main/java/net/fabricmc/filament/task/ExtractZipEntryTask.java
deleted file mode 100644
index 52f50d58e3..0000000000
--- a/filament/src/main/java/net/fabricmc/filament/task/ExtractZipEntryTask.java
+++ /dev/null
@@ -1,24 +0,0 @@
-package net.fabricmc.filament.task;
-
-import java.io.IOException;
-import java.nio.file.Files;
-
-import org.gradle.api.provider.Property;
-import org.gradle.api.tasks.Input;
-import org.gradle.api.tasks.TaskAction;
-
-import net.fabricmc.filament.task.base.FilamentTask;
-import net.fabricmc.filament.task.base.WithFileInput;
-import net.fabricmc.filament.task.base.WithFileOutput;
-import net.fabricmc.loom.util.ZipUtils;
-
-public abstract class ExtractZipEntryTask extends FilamentTask implements WithFileInput, WithFileOutput {
-	@Input
-	public abstract Property<String> getEntry();
-
-	@TaskAction
-	public void run() throws IOException {
-		byte[] bytes = ZipUtils.unpack(getInputPath(), getEntry().get());
-		Files.write(getOutputPath(), bytes);
-	}
-}
diff --git a/filament/src/main/java/net/fabricmc/filament/task/RemapUnpickDefinitionsTask.java b/filament/src/main/java/net/fabricmc/filament/task/RemapUnpickDefinitionsTask.java
index 97950fd579..0e5fb0afa5 100644
--- a/filament/src/main/java/net/fabricmc/filament/task/RemapUnpickDefinitionsTask.java
+++ b/filament/src/main/java/net/fabricmc/filament/task/RemapUnpickDefinitionsTask.java
@@ -1,9 +1,7 @@
 package net.fabricmc.filament.task;
 
-import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
-import java.io.FileReader;
 import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.util.HashMap;
@@ -30,11 +28,9 @@ import org.gradle.workers.WorkerExecutor;
 
 import net.fabricmc.filament.util.FileUtil;
 import net.fabricmc.filament.util.UnpickUtil;
-import net.fabricmc.mapping.tree.ClassDef;
-import net.fabricmc.mapping.tree.FieldDef;
-import net.fabricmc.mapping.tree.MethodDef;
-import net.fabricmc.mapping.tree.TinyMappingFactory;
-import net.fabricmc.mapping.tree.TinyTree;
+import net.fabricmc.mappingio.MappingReader;
+import net.fabricmc.mappingio.tree.MappingTree;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
 public abstract class RemapUnpickDefinitionsTask extends DefaultTask {
 	@InputFile
@@ -98,28 +94,28 @@ public abstract class RemapUnpickDefinitionsTask extends DefaultTask {
 				Map<String, String> classMappings = new HashMap<>();
 				Map<MethodKey, String> methodMappings = new HashMap<>();
 				Map<FieldKey, String> fieldMappings = new HashMap<>();
-				String fromM = getParameters().getSourceNamespace().get();
-				String toM = getParameters().getTargetNamespace().get();
 
-				try (BufferedReader reader = new BufferedReader(new FileReader(getParameters().getMappings().getAsFile().get()))) {
-					TinyTree tinyTree = TinyMappingFactory.loadWithDetection(reader);
+				final MemoryMappingTree mappingTree = new MemoryMappingTree();
+				MappingReader.read(getParameters().getMappings().getAsFile().get().toPath(), mappingTree);
 
-					for (ClassDef classDef : tinyTree.getClasses()) {
-						classMappings.put(classDef.getName(fromM), classDef.getName(toM));
+				final int fromM = mappingTree.getNamespaceId(getParameters().getSourceNamespace().get());
+				final int toM = mappingTree.getNamespaceId(getParameters().getTargetNamespace().get());
 
-						for (MethodDef methodDef : classDef.getMethods()) {
-							methodMappings.put(
-									new MethodKey(classDef.getName(fromM), methodDef.getName(fromM), methodDef.getDescriptor(fromM)),
-									methodDef.getName(toM)
-							);
-						}
+				for (MappingTree.ClassMapping classDef : mappingTree.getClasses()) {
+					classMappings.put(classDef.getName(fromM), classDef.getName(toM));
 
-						for (FieldDef fieldDef : classDef.getFields()) {
-							fieldMappings.put(
-									new FieldKey(classDef.getName(fromM), fieldDef.getName(fromM)),
-									fieldDef.getName(toM)
-							);
-						}
+					for (MappingTree.MethodMapping methodDef : classDef.getMethods()) {
+						methodMappings.put(
+								new MethodKey(classDef.getName(fromM), methodDef.getName(fromM), methodDef.getDesc(fromM)),
+								methodDef.getName(toM)
+						);
+					}
+
+					for (MappingTree.FieldMapping fieldDef : classDef.getFields()) {
+						fieldMappings.put(
+								new FieldKey(classDef.getName(fromM), fieldDef.getName(fromM)),
+								fieldDef.getName(toM)
+						);
 					}
 				}
 
diff --git a/filament/src/main/java/net/fabricmc/filament/task/enigma/ConvertMappingsTask.java b/filament/src/main/java/net/fabricmc/filament/task/enigma/ConvertMappingsTask.java
deleted file mode 100644
index 065bcb3c7f..0000000000
--- a/filament/src/main/java/net/fabricmc/filament/task/enigma/ConvertMappingsTask.java
+++ /dev/null
@@ -1,34 +0,0 @@
-package net.fabricmc.filament.task.enigma;
-
-import java.util.List;
-
-import cuchaz.enigma.command.Command;
-import cuchaz.enigma.command.ConvertMappingsCommand;
-import org.gradle.api.provider.Property;
-import org.gradle.api.tasks.Input;
-
-import net.fabricmc.filament.task.base.WithFileInput;
-import net.fabricmc.filament.task.base.WithFileOutput;
-
-public abstract class ConvertMappingsTask extends EnigmaCommandTask implements WithFileInput, WithFileOutput {
-	@Input
-	public abstract Property<String> getInputMappingsFormat();
-
-	@Input
-	public abstract Property<String> getOutputMappingsFormat();
-
-	@Override
-	public Class<? extends Command> getCommandClass() {
-		return ConvertMappingsCommand.class;
-	}
-
-	@Override
-	protected List<String> getArguments() {
-		return List.of(
-			getInputMappingsFormat().get(),
-			getInputFile().getAbsolutePath(),
-			getOutputMappingsFormat().get(),
-			getOutputFile().getAbsolutePath()
-		);
-	}
-}
diff --git a/filament/src/main/java/net/fabricmc/filament/task/mappingio/ConvertMappingsTask.java b/filament/src/main/java/net/fabricmc/filament/task/mappingio/ConvertMappingsTask.java
new file mode 100644
index 0000000000..145b9e3b18
--- /dev/null
+++ b/filament/src/main/java/net/fabricmc/filament/task/mappingio/ConvertMappingsTask.java
@@ -0,0 +1,14 @@
+package net.fabricmc.filament.task.mappingio;
+
+import java.io.IOException;
+
+import net.fabricmc.filament.task.base.WithFileInput;
+import net.fabricmc.mappingio.MappingReader;
+import net.fabricmc.mappingio.MappingWriter;
+
+public abstract class ConvertMappingsTask extends MappingOutputTask implements WithFileInput {
+	@Override
+	void run(MappingWriter writer) throws IOException {
+		MappingReader.read(getInputPath(), writer);
+	}
+}
diff --git a/filament/src/main/java/net/fabricmc/filament/task/mappingio/MappingOutputTask.java b/filament/src/main/java/net/fabricmc/filament/task/mappingio/MappingOutputTask.java
new file mode 100644
index 0000000000..5cd26a4ebb
--- /dev/null
+++ b/filament/src/main/java/net/fabricmc/filament/task/mappingio/MappingOutputTask.java
@@ -0,0 +1,26 @@
+package net.fabricmc.filament.task.mappingio;
+
+import java.io.IOException;
+
+import org.gradle.api.provider.Property;
+import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.TaskAction;
+
+import net.fabricmc.filament.task.base.FilamentTask;
+import net.fabricmc.filament.task.base.WithFileOutput;
+import net.fabricmc.mappingio.MappingWriter;
+import net.fabricmc.mappingio.format.MappingFormat;
+
+public abstract class MappingOutputTask extends FilamentTask implements WithFileOutput {
+	@Input
+	public abstract Property<MappingFormat> getOutputFormat();
+
+	@TaskAction
+	public final void run() throws IOException {
+		try (MappingWriter mappingWriter = MappingWriter.create(getOutputPath(), getOutputFormat().get())) {
+			run(mappingWriter);
+		}
+	}
+
+	abstract void run(MappingWriter writer) throws IOException;
+}
diff --git a/filament/src/main/java/net/fabricmc/filament/task/mappingio/MergeMappingsTask.java b/filament/src/main/java/net/fabricmc/filament/task/mappingio/MergeMappingsTask.java
new file mode 100644
index 0000000000..0fb4a01849
--- /dev/null
+++ b/filament/src/main/java/net/fabricmc/filament/task/mappingio/MergeMappingsTask.java
@@ -0,0 +1,75 @@
+package net.fabricmc.filament.task.mappingio;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import org.gradle.api.file.ConfigurableFileCollection;
+import org.gradle.api.tasks.InputFiles;
+
+import net.fabricmc.mappingio.MappingReader;
+import net.fabricmc.mappingio.MappingWriter;
+import net.fabricmc.mappingio.adapter.MappingDstNsReorder;
+import net.fabricmc.mappingio.adapter.MappingNsCompleter;
+import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
+import net.fabricmc.mappingio.tree.MappingTree;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
+
+public abstract class MergeMappingsTask extends MappingOutputTask {
+	@InputFiles
+	public abstract ConfigurableFileCollection getMappingInputs();
+
+	@Override
+	void run(MappingWriter writer) throws IOException {
+		var mappingTree = new MemoryMappingTree();
+
+		for (File file : getMappingInputs().getFiles()) {
+			var nsSwitch = new MappingSourceNsSwitch(mappingTree, "intermediary");
+			MappingReader.read(file.toPath(), nsSwitch);
+		}
+
+		fixInnerClasses(mappingTree);
+
+		var nsCompleter = new MappingNsCompleter(writer, Map.of("named", "intermediary"), true);
+		var dstReorder = new MappingDstNsReorder(nsCompleter, List.of("official", "named"));
+		mappingTree.accept(dstReorder);
+	}
+
+	private void fixInnerClasses(MemoryMappingTree mappingTree) {
+		int named = mappingTree.getNamespaceId("named");
+
+		for (MappingTree.ClassMapping entry : mappingTree.getClasses()) {
+			String name = entry.getName(named);
+
+			if (name != null) {
+				continue;
+			}
+
+			entry.setDstName(matchEnclosingClass(entry.getSrcName(), mappingTree), named);
+		}
+	}
+
+	/*
+	 * Takes something like net/minecraft/class_123$class_124 that doesn't have a mapping, tries to find net/minecraft/class_123
+	 * , say the mapping of net/minecraft/class_123 is path/to/someclass and then returns a class of the form
+	 * path/to/someclass$class124
+	 */
+	private String matchEnclosingClass(String sharedName, MemoryMappingTree mappingTree) {
+		final int named = mappingTree.getNamespaceId("named");
+		final String[] path = sharedName.split(Pattern.quote("$"));
+
+		for (int i = path.length - 2; i >= 0; i--) {
+			final String currentPath = String.join("$", Arrays.copyOfRange(path, 0, i + 1));
+			final MappingTree.ClassMapping match = mappingTree.getClass(currentPath);
+
+			if (match != null && match.getName(named) != null) {
+				return match.getName(named) + "$" + String.join("$", Arrays.copyOfRange(path, i + 1, path.length));
+			}
+		}
+
+		return sharedName;
+	}
+}
diff --git a/filament/src/main/java/net/fabricmc/filament/task/minecraft/MergeMinecraftTask.java b/filament/src/main/java/net/fabricmc/filament/task/minecraft/MergeMinecraftTask.java
index 873ba910b9..986194fab8 100644
--- a/filament/src/main/java/net/fabricmc/filament/task/minecraft/MergeMinecraftTask.java
+++ b/filament/src/main/java/net/fabricmc/filament/task/minecraft/MergeMinecraftTask.java
@@ -7,7 +7,7 @@ import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
 
 import net.fabricmc.filament.task.base.FileOutputTask;
-import net.fabricmc.stitch.merge.JarMerger;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftJarMerger;
 
 public abstract class MergeMinecraftTask extends FileOutputTask {
 	@InputFile
@@ -18,7 +18,7 @@ public abstract class MergeMinecraftTask extends FileOutputTask {
 
 	@TaskAction
 	public void run() throws IOException {
-		try (JarMerger jarMerger = new JarMerger(
+		try (MinecraftJarMerger jarMerger = new MinecraftJarMerger(
 				getClientJar().getAsFile().get(),
 				getServerJar().getAsFile().get(),
 				getOutput().getAsFile().get())) {
diff --git a/gradle.properties b/gradle.properties
index e547019424..d3f5136069 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -4,12 +4,10 @@ org.gradle.parallel=true
 org.gradle.configuration-cache=true
 
 enigma_version=2.3.1
-stitch_version=0.6.1
 unpick_version=2.3.0
 cfr_version=0.1.1
 name_proposal_version=0.1.4
-tiny_remapper_version=0.8.5
-asm_version=9.4
+asm_version=9.5
 
 # Javadoc generation/linking
 fabric_loader_version=0.14.14
@@ -17,6 +15,6 @@ jetbrains_annotations_version=23.0.0
 mappingpoet_version=0.3.2
 
 # Build logic
-tiny_mappings_parser_version=0.3.0+build.17
+tiny_remapper_version=0.8.5
 junit_version=5.7.1
 assertj_version=3.19.0