diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0c2a3f3..479cd29 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,30 +1,49 @@
-# Automatically build the project and run any configured tests for every push
-# and submitted pull request. This can help catch issues that only occur on
-# certain platforms or Java versions, and provides a first line of defence
-# against bad commits.
+# Build the mod against every Minecraft variant Stonecutter is configured for.
+# Each matrix job builds one variant (1.21, 1.21.6, 26.1) and uploads its jar.
+# Running `./gradlew build` from the root would also work but the matrix gives
+# clearer failure attribution and parallel execution.
 
 name: build
 on: [pull_request, push]
 
 jobs:
   build:
+    name: build mc${{ matrix.mc }}
     runs-on: ubuntu-24.04
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - mc: '1.21'
+            java: '21'
+          - mc: '1.21.6'
+            java: '21'
+          - mc: '26.1'
+            java: '25'
     steps:
       - name: checkout repository
         uses: actions/checkout@v6
+
       - name: validate gradle wrapper
         uses: gradle/actions/wrapper-validation@v6
-      - name: setup jdk
+
+      - name: setup jdk ${{ matrix.java }}
         uses: actions/setup-java@v5
         with:
-          java-version: '25'
+          java-version: ${{ matrix.java }}
           distribution: 'microsoft'
+
+      # Stonecutter's `build.gradle` uses Java toolchains, so loom can compile
+      # against an older JDK even when Gradle itself runs on a newer one. We
+      # still set the matrix Java as the daemon JVM for simplicity.
       - name: make gradle wrapper executable
         run: chmod +x ./gradlew
-      - name: build
-        run: ./gradlew build
-      - name: capture build artifacts
+
+      - name: build :${{ matrix.mc }}:build
+        run: ./gradlew :${{ matrix.mc }}:build --stacktrace
+
+      - name: upload jar
         uses: actions/upload-artifact@v7
         with:
-          name: Artifacts
-          path: build/libs/
\ No newline at end of file
+          name: betterhud-mc${{ matrix.mc }}
+          path: versions/${{ matrix.mc }}/build/libs/*.jar
diff --git a/.gitignore b/.gitignore
index c476faf..8c52ed7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,6 +32,14 @@ bin/
 
 run/
 
+# stonecutter
+
+versions/*/.gradle/
+versions/*/build/
+versions/*/run/
+versions/*/src/
+*.stonecutter.tmp
+
 # java
 
 hs_err_*.log
diff --git a/build.gradle b/build.gradle
index 41f2871..3b8a1b5 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,87 +1,131 @@
 plugins {
-	id 'net.fabricmc.fabric-loom' version "${loom_version}"
+	// Loom 1.14+ splits into two sibling plugins:
+	//  - `net.fabricmc.fabric-loom-remap` handles obfuscated MC (1.21.x with intermediary)
+	//  - `net.fabricmc.fabric-loom`       handles unobfuscated MC (26.1+, Mojang names native)
+	// We declare both with `apply false` and pick the right one for the current variant.
+	id 'net.fabricmc.fabric-loom-remap' version "${loom_version}" apply false
+	id 'net.fabricmc.fabric-loom' version "${loom_version}" apply false
 	id 'maven-publish'
 }
 
-version = project.mod_version
+def mcVersion = stonecutter.current.version
+def isLegacy = stonecutter.eval(mcVersion, '<26')      // 1.21.x family
+def hasHudElementRegistry = stonecutter.eval(mcVersion, '>=1.21.6')  // 1.21.6+ and 26+
+
+apply plugin: isLegacy ? 'net.fabricmc.fabric-loom-remap' : 'net.fabricmc.fabric-loom'
+
+// `stonecutter` is injected into each version subproject. `stonecutter.current.version`
+// is the MC string, e.g. "1.21", "1.21.6", "26.1".
+// Per-MC Java version (21 for 1.21.x, 25 for 26.1+).
+def javaVersionInt = Integer.parseInt(project.java_version)
+def javaLang = JavaVersion.toVersion(javaVersionInt)
+def mixinJavaCompat = "JAVA_${javaVersionInt}"
+
+version = "${project.mod_version}+mc${mcVersion}"
 group = project.maven_group
 
+base {
+	archivesName = project.archives_base_name
+}
+
 repositories {
-	// Add repositories to retrieve artifacts from in here.
-	// You should only use this when depending on other mods because
-	// Loom adds the essential maven repositories to download Minecraft and libraries from automatically.
-	// See https://docs.gradle.org/current/userguide/declaring_repositories.html
-	// for more information about repositories.
-
-    maven { url "https://maven.shedaniel.me/" }
-    maven { url "https://maven.terraformersmc.com/releases/" }
+	maven { url 'https://maven.shedaniel.me/' }
+	maven { url 'https://maven.terraformersmc.com/releases/' }
 }
 
-configurations.configureEach {
-	if (name.toLowerCase().contains('annotationprocessor')) {
-		exclude group: 'org.ow2.asm'
+// MC 26+ uses fabric-rendering-v1's transitive deps but rejects ASM coming from
+// annotation processors; matches main's existing build.
+if (!isLegacy) {
+	configurations.configureEach {
+		if (name.toLowerCase().contains('annotationprocessor')) {
+			exclude group: 'org.ow2.asm'
+		}
 	}
 }
 
+// MC 26+ ships with Mojang official names baked into the runtime, so loom skips
+// the intermediary remap entirely - mods link directly via `implementation`
+// and `mappings` must NOT be declared.
+// 1.21.x uses intermediary at runtime, so deps must go through `modImplementation`
+// for loom to remap them, and `mappings loom.officialMojangMappings()` is required.
 dependencies {
-	// To change the versions see the gradle.properties file
 	minecraft "com.mojang:minecraft:${project.minecraft_version}"
-	
-	implementation "net.fabricmc:fabric-loader:${project.loader_version}"
-
-	// Fabric API. This is technically optional, but you probably want it anyway.
-	implementation include(fabricApi.module("fabric-api-base", project.fabric_api_version))
-	implementation include(fabricApi.module("fabric-rendering-v1", project.fabric_api_version))
-	
-	implementation include("com.terraformersmc:modmenu:${project.modmenu_version}")
-	implementation include("me.shedaniel.cloth:cloth-config-fabric:${project.cloth_config_version}") {
-        exclude(group: "net.fabricmc.fabric-api")
-    }
+
+	if (isLegacy) {
+		mappings loom.officialMojangMappings()
+
+		modImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
+		modImplementation include(fabricApi.module('fabric-api-base', project.fabric_api_version))
+		modImplementation include(fabricApi.module('fabric-rendering-v1', project.fabric_api_version))
+
+		// 1.21 (pre-1.21.6) needs lifecycle-events as an explicit module; later versions
+		// pull it transitively through rendering-v1.
+		if (!hasHudElementRegistry) {
+			modImplementation include(fabricApi.module('fabric-lifecycle-events-v1', project.fabric_api_version))
+		}
+
+		modImplementation include("com.terraformersmc:modmenu:${project.modmenu_version}")
+		modImplementation include("me.shedaniel.cloth:cloth-config-fabric:${project.cloth_config_version}") {
+			exclude(group: 'net.fabricmc.fabric-api')
+		}
+	} else {
+		implementation "net.fabricmc:fabric-loader:${project.loader_version}"
+		implementation include(fabricApi.module('fabric-api-base', project.fabric_api_version))
+		implementation include(fabricApi.module('fabric-rendering-v1', project.fabric_api_version))
+
+		implementation include("com.terraformersmc:modmenu:${project.modmenu_version}")
+		implementation include("me.shedaniel.cloth:cloth-config-fabric:${project.cloth_config_version}") {
+			exclude(group: 'net.fabricmc.fabric-api')
+		}
+	}
 }
 
 processResources {
-	inputs.property "version", project.version
+	def expansion = [
+		version       : project.version,
+		minecraftReq  : project.mc_dep,
+		loaderReq     : project.loader_dep,
+		javaReq       : ">=${javaVersionInt}",
+		javaCompat    : mixinJavaCompat
+	]
+	inputs.properties expansion
 
-	filesMatching("fabric.mod.json") {
-		expand "version": inputs.properties.version
+	filesMatching('fabric.mod.json') {
+		expand expansion
+	}
+	filesMatching('betterhud.mixins.json') {
+		expand expansion
 	}
 }
 
 tasks.withType(JavaCompile).configureEach {
-	it.options.release = 25
+	it.options.release = javaVersionInt
 }
 
 java {
-	// Loom will automatically attach sourcesJar to a RemapSourcesJar task and to the "build" task
-	// if it is present.
-	// If you remove this line, sources will not be generated.
 	withSourcesJar()
-
-	sourceCompatibility = JavaVersion.VERSION_25
-	targetCompatibility = JavaVersion.VERSION_25
+	sourceCompatibility = javaLang
+	targetCompatibility = javaLang
+	toolchain {
+		languageVersion = JavaLanguageVersion.of(javaVersionInt)
+	}
 }
 
 jar {
-	inputs.property "projectName", project.name
-
-	from("LICENSE") {
-		rename { "${it}_${project.name}"}
+	def archiveName = base.archivesName.get()
+	from('../../LICENSE') {
+		rename { "${it}_${archiveName}" }
 	}
 }
 
-// configure the maven publication
 publishing {
 	publications {
-		create("mavenJava", MavenPublication) {
+		create('mavenJava', MavenPublication) {
+			artifactId = "${project.archives_base_name}-mc${mcVersion}"
 			from components.java
 		}
 	}
-
-	// See https://docs.gradle.org/current/userguide/publishing_maven.html for information on how to set up publishing.
 	repositories {
-		// Add repositories to publish to here.
-		// Notice: This block does NOT have the same function as the block in the top level.
-		// The repositories here will be used for publishing your artifact, not for
-		// retrieving dependencies.
+		// Add publish repos here if/when needed.
 	}
-}
\ No newline at end of file
+}
diff --git a/gradle.properties b/gradle.properties
index a7faad0..07e740a 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,22 +1,18 @@
 # Done to increase the memory available to gradle.
-org.gradle.jvmargs=-Xmx1G
+org.gradle.jvmargs=-Xmx2G
 org.gradle.parallel=true
 
 # IntelliJ IDEA is not yet fully compatible with configuration cache, see: https://github.com/FabricMC/fabric-loom/issues/1349
 org.gradle.configuration-cache=false
 
-# Fabric Properties
-# check these on https://fabricmc.net/develop
-minecraft_version=26.1
-loader_version=0.19.2
+# Acknowledge using Groovy DSL with Stonecutter (Kotlin DSL is recommended but Groovy works).
+dev.kikugie.stonecutter.hard_mode=true
+
+# Single loom version covers all MC variants. The `fabric-loom-remap` plugin id
+# handles obfuscated MC (1.21.x), while `fabric-loom` handles unobfuscated MC (26.1+).
 loom_version=1.16-SNAPSHOT
 
-# Mod Properties
+# Mod Properties (shared)
 mod_version=2.1.0
 maven_group=dsns.betterhud
 archives_base_name=betterhud
-
-# Dependencies
-fabric_api_version=0.145.1+26.1
-modmenu_version=18.0.0-alpha.8
-cloth_config_version=26.1.154
\ No newline at end of file
diff --git a/gradlew b/gradlew
old mode 100644
new mode 100755
diff --git a/settings.gradle b/settings.gradle
index bcb1c6e..c38a828 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -4,10 +4,34 @@ pluginManagement {
 			name = 'Fabric'
 			url = 'https://maven.fabricmc.net/'
 		}
+		maven {
+			name = 'Stonecutter Releases'
+			url = 'https://maven.kikugie.dev/releases'
+		}
+		maven {
+			name = 'Stonecutter Snapshots'
+			url = 'https://maven.kikugie.dev/snapshots'
+		}
 		mavenCentral()
 		gradlePluginPortal()
 	}
 }
 
-// Should match your modid
+plugins {
+	id 'dev.kikugie.stonecutter' version '0.9.3'
+}
+
+stonecutter {
+	create(rootProject) {
+		// Each entry is one buildable variant. The string is both the subproject name
+		// and the MC version. These cover support/1.21-1.21.5, support/1.21.6-1.21.11,
+		// and main 26.1.
+		versions('1.21', '1.21.6', '26.1')
+
+		// vcsVersion is the variant whose form is used as the canonical (active) version
+		// in source. We pick 26.1 so `git diff main` stays small.
+		vcsVersion = '26.1'
+	}
+}
+
 rootProject.name = 'betterhud'
diff --git a/src/main/java/dsns/betterhud/BetterHUD.java b/src/main/java/dsns/betterhud/BetterHUD.java
index bbf7edb..39bd452 100644
--- a/src/main/java/dsns/betterhud/BetterHUD.java
+++ b/src/main/java/dsns/betterhud/BetterHUD.java
@@ -8,8 +8,16 @@
 import net.fabricmc.api.EnvType;
 import net.fabricmc.api.Environment;
 import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
+//? if >=1.21.6 {
 import net.fabricmc.fabric.api.client.rendering.v1.hud.HudElementRegistry;
+//?} else {
+/*import net.fabricmc.fabric.api.client.rendering.v1.HudRenderCallback;
+*///?}
+//? if >=26 {
 import net.minecraft.resources.Identifier;
+//?} else if >=1.21.6 {
+/*import net.minecraft.resources.ResourceLocation;*/
+//?}
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -39,10 +47,19 @@ public void onInitializeClient() {
 
         BetterHUDGUI betterHUDGUI = new BetterHUDGUI();
 
+        //? if >=26 {
         HudElementRegistry.addLast(
             Identifier.fromNamespaceAndPath("betterhud", "hud"),
             betterHUDGUI::onHudRender
         );
+        //?} else if >=1.21.6 {
+        /*HudElementRegistry.addLast(
+            ResourceLocation.fromNamespaceAndPath("betterhud", "hud"),
+            betterHUDGUI::onHudRender
+        );*/
+        //?} else {
+        /*HudRenderCallback.EVENT.register(betterHUDGUI);
+        *///?}
         ClientTickEvents.START_CLIENT_TICK.register(betterHUDGUI);
     }
 }
diff --git a/src/main/java/dsns/betterhud/BetterHUDGUI.java b/src/main/java/dsns/betterhud/BetterHUDGUI.java
index 7d2b187..aea1e82 100644
--- a/src/main/java/dsns/betterhud/BetterHUDGUI.java
+++ b/src/main/java/dsns/betterhud/BetterHUDGUI.java
@@ -6,11 +6,22 @@
 import it.unimi.dsi.fastutil.objects.ObjectArrayList;
 import java.util.List;
 import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
+//? if <1.21.6 {
+/*import net.fabricmc.fabric.api.client.rendering.v1.HudRenderCallback;
+*///?}
 import net.minecraft.client.DeltaTracker;
 import net.minecraft.client.Minecraft;
+//? if >=26 {
 import net.minecraft.client.gui.GuiGraphicsExtractor;
+//?} else {
+/*import net.minecraft.client.gui.GuiGraphics;
+*///?}
 
+//? if >=1.21.6 {
 public class BetterHUDGUI implements ClientTickEvents.StartTick {
+//?} else {
+/*public class BetterHUDGUI implements HudRenderCallback, ClientTickEvents.StartTick {
+*///?}
 
     public static int verticalPadding = 4;
     public static int horizontalPadding = 4;
@@ -68,7 +79,11 @@ public void onStartTick(Minecraft client) {
     }
 
     public void onHudRender(
+        //? if >=26 {
         GuiGraphicsExtractor drawContext,
+        //?} else {
+        /*GuiGraphics drawContext,
+        *///?}
         DeltaTracker tickCounter
     ) {
         if (client.getDebugOverlay().showDebugScreen()) return;
@@ -145,7 +160,11 @@ public void onHudRender(
     }
 
     private void drawString(
+        //? if >=26 {
         GuiGraphicsExtractor drawContext,
+        //?} else {
+        /*GuiGraphics drawContext,
+        *///?}
         CustomText text,
         int x,
         int y
@@ -160,6 +179,7 @@ private void drawString(
             text.backgroundColor
         );
 
+        //? if >=26 {
         drawContext.text(
             client.font,
             text.text,
@@ -168,5 +188,15 @@ private void drawString(
             text.color,
             true
         );
+        //?} else {
+        /*drawContext.drawString(
+            client.font,
+            text.text,
+            x + horizontalPadding,
+            y + verticalPadding,
+            text.color,
+            true
+        );
+        *///?}
     }
 }
diff --git a/src/main/java/dsns/betterhud/mods/Biome.java b/src/main/java/dsns/betterhud/mods/Biome.java
index 73289be..e455125 100644
--- a/src/main/java/dsns/betterhud/mods/Biome.java
+++ b/src/main/java/dsns/betterhud/mods/Biome.java
@@ -5,8 +5,15 @@
 import dsns.betterhud.util.ModSettings;
 import java.util.LinkedHashMap;
 import java.util.Map;
+//? if <26 {
+/*import java.util.Optional;
+*///?}
 import net.minecraft.client.Minecraft;
+//? if >=26 {
 import net.minecraft.core.Holder;
+//?} else {
+/*import net.minecraft.resources.ResourceKey;
+*///?}
 import net.minecraft.world.entity.player.Player;
 
 public class Biome implements BaseMod {
@@ -30,11 +37,20 @@ public CustomText onStartTick(Minecraft client) {
         if (player == null) return null;
 
         // have to specify this because name of class is Biome
+        //? if >=26 {
         Holder<net.minecraft.world.level.biome.Biome> biome = client.level.getBiome(player.blockPosition());
 
         if (!biome.unwrapKey().isPresent()) return null;
 
         String biomeString = formatSnakeCase(biome.getRegisteredName().replace("minecraft:", ""));
+        //?} else {
+        /*Optional<ResourceKey<net.minecraft.world.level.biome.Biome>> biome =
+            client.level.getBiome(player.blockPosition()).unwrapKey();
+
+        if (!biome.isPresent()) return null;
+
+        String biomeString = formatSnakeCase(biome.get().location().getPath());
+        *///?}
 
         // used to maintain order when iterating
         LinkedHashMap<String, Integer> biomeColors = new LinkedHashMap<>();
diff --git a/src/main/resources/betterhud.mixins.json b/src/main/resources/betterhud.mixins.json
index 370eecf..c35b39c 100644
--- a/src/main/resources/betterhud.mixins.json
+++ b/src/main/resources/betterhud.mixins.json
@@ -1,7 +1,7 @@
 {
 	"required": true,
 	"package": "dsns.betterhud.mixin",
-	"compatibilityLevel": "JAVA_25",
+	"compatibilityLevel": "${javaCompat}",
 	"client": [],
 	"injectors": {
 		"defaultRequire": 1
@@ -9,4 +9,4 @@
 	"overwrites": {
 		"requireAnnotations": true
 	}
-}
\ No newline at end of file
+}
diff --git a/src/main/resources/fabric.mod.json b/src/main/resources/fabric.mod.json
index 31b270b..b116dc0 100644
--- a/src/main/resources/fabric.mod.json
+++ b/src/main/resources/fabric.mod.json
@@ -21,8 +21,8 @@
 		"betterhud.mixins.json"
 	],
 	"depends": {
-		"fabricloader": ">=0.19",
-		"minecraft": ">=26",
-		"java": ">=25"
+		"fabricloader": "${loaderReq}",
+		"minecraft": "${minecraftReq}",
+		"java": "${javaReq}"
 	}
-}
\ No newline at end of file
+}
diff --git a/stonecutter.gradle b/stonecutter.gradle
new file mode 100644
index 0000000..55aa818
--- /dev/null
+++ b/stonecutter.gradle
@@ -0,0 +1,11 @@
+plugins {
+	id 'dev.kikugie.stonecutter'
+}
+
+// The "active" version determines which variant the source tree currently shows
+// uncommented. Switch with `./gradlew "Set active version to <ver>"` (Stonecutter task).
+stonecutter.active('26.1') /* [SC] DO NOT EDIT */
+
+// Stonecutter 0.7+ no longer needs explicit `registerChiseled` task: running
+// `./gradlew build` from the root automatically runs `build` for every version
+// subproject. Per-version commands like `./gradlew :1.21:build` also work.
diff --git a/versions/1.21.6/gradle.properties b/versions/1.21.6/gradle.properties
new file mode 100644
index 0000000..1c59190
--- /dev/null
+++ b/versions/1.21.6/gradle.properties
@@ -0,0 +1,14 @@
+# Builds against MC 1.21.9 (a stable point in the 1.21.6-1.21.11 range).
+# fabric.mod.json declares >=1.21.6 <1.22 so it loads on 1.21.6-1.21.11.
+minecraft_version=1.21.9
+loader_version=0.17.3
+java_version=21
+
+# fabric.mod.json range
+mc_dep=>=1.21.6 <1.22
+loader_dep=>=0.16.10
+
+# Fabric API + ecosystem (matches support/1.21.6-1.21.11 branch).
+fabric_api_version=0.134.0+1.21.9
+modmenu_version=15.0.2
+cloth_config_version=19.0.147
diff --git a/versions/1.21/gradle.properties b/versions/1.21/gradle.properties
new file mode 100644
index 0000000..4d2e6ac
--- /dev/null
+++ b/versions/1.21/gradle.properties
@@ -0,0 +1,14 @@
+# Builds against MC 1.21 itself (lowest in the 1.21-1.21.5 range, for max
+# backward compat). fabric.mod.json declares ~1.21 so it loads on 1.21-1.21.5.
+minecraft_version=1.21
+loader_version=0.17.3
+java_version=21
+
+# fabric.mod.json range
+mc_dep=~1.21
+loader_dep=>=0.15.11
+
+# Fabric API + ecosystem (matches support/1.21-1.21.5 branch).
+fabric_api_version=0.102.0+1.21
+modmenu_version=14.0.2
+cloth_config_version=19.0.147
diff --git a/versions/26.1/gradle.properties b/versions/26.1/gradle.properties
new file mode 100644
index 0000000..c5050b1
--- /dev/null
+++ b/versions/26.1/gradle.properties
@@ -0,0 +1,12 @@
+minecraft_version=26.1
+loader_version=0.19.2
+java_version=25
+
+# fabric.mod.json range
+mc_dep=>=26
+loader_dep=>=0.19
+
+# Fabric API + ecosystem
+fabric_api_version=0.145.1+26.1
+modmenu_version=18.0.0-alpha.8
+cloth_config_version=26.1.154