diff --git a/.github/scripts/retry.sh b/.github/scripts/retry.sh
new file mode 100755
index 0000000..8cb5452
--- /dev/null
+++ b/.github/scripts/retry.sh
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Runs a command and retries it on failure, to ride out transient network
+# flakes (interrupted maven downloads, brief mirror outages, and the like).
+#
+#   retry.sh <command> [args...]
+#
+# RETRY_ATTEMPTS (default 3) sets the total number of attempts; the pause
+# between attempts grows with each failure.
+set -uo pipefail
+
+attempts="${RETRY_ATTEMPTS:-3}"
+code=0
+for ((i = 1; i <= attempts; i++)); do
+	"$@"
+	code=$?
+	[ "$code" -eq 0 ] && exit 0
+	if ((i < attempts)); then
+		delay=$((i * 15))
+		echo "::warning::Attempt ${i}/${attempts} of '$*' failed with exit code ${code}; retrying in ${delay}s"
+		sleep "$delay"
+	fi
+done
+echo "::error::All ${attempts} attempts of '$*' failed"
+exit "$code"
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 20256d5..8a626a6 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -55,11 +55,17 @@ jobs:
           java-version: ${{ matrix.java }}
           distribution: 'microsoft'
 
+      - name: setup gradle with dependency caching
+        # Caches Gradle dependencies between runs (written on the default
+        # branch, read everywhere), so a flaky maven rarely has to be hit.
+        uses: gradle/actions/setup-gradle@v6
+
       - name: make gradle wrapper executable
         run: chmod +x ./gradlew
 
       - name: build :${{ matrix.mc }}:build
-        run: ./gradlew :${{ matrix.mc }}:build --stacktrace
+        # retry.sh reruns the build on transient failures (flaky maven downloads).
+        run: bash .github/scripts/retry.sh ./gradlew :${{ matrix.mc }}:build --stacktrace
 
       - name: upload jar
         uses: actions/upload-artifact@v7
@@ -97,6 +103,9 @@ jobs:
           java-version: ${{ matrix.java }}
           distribution: 'microsoft'
 
+      - name: setup gradle with dependency caching
+        uses: gradle/actions/setup-gradle@v6
+
       - name: make gradle wrapper executable
         run: chmod +x ./gradlew
 
@@ -109,7 +118,11 @@ jobs:
         run: bash .github/scripts/generate-test-world.sh ${{ matrix.mc }}
 
       - name: launch minecraft ${{ matrix.mc }} with mod
-        run: ./gradlew :launchtest:runProductionClientGameTest -PtestMcVersion=${{ matrix.mc }} --stacktrace
+        # Two attempts (not the default three): a real game crash fails both,
+        # and a second full launch still fits the 40-minute job timeout.
+        env:
+          RETRY_ATTEMPTS: '2'
+        run: bash .github/scripts/retry.sh ./gradlew :launchtest:runProductionClientGameTest -PtestMcVersion=${{ matrix.mc }} --stacktrace
 
       - name: check survival world screenshot was taken
         run: test -n "$(find launchtest/run/screenshots -name '*betterhud-survival-world.png' -print -quit 2>/dev/null)"
@@ -228,11 +241,14 @@ jobs:
             25
           distribution: 'microsoft'
 
+      - name: setup gradle with dependency caching
+        uses: gradle/actions/setup-gradle@v6
+
       - name: make gradle wrapper executable
         run: chmod +x ./gradlew
 
       - name: build all variants and write the upload guide
-        run: ./gradlew modrinthBundle --stacktrace "-Porg.gradle.java.installations.paths=$JAVA_HOME_21_X64,$JAVA_HOME_25_X64"
+        run: bash .github/scripts/retry.sh ./gradlew modrinthBundle --stacktrace "-Porg.gradle.java.installations.paths=$JAVA_HOME_21_X64,$JAVA_HOME_25_X64"
 
       - name: upload modrinth bundle
         uses: actions/upload-artifact@v7
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 9ab1350..90a291f 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -113,11 +113,16 @@ jobs:
           java-version: ${{ matrix.java }}
           distribution: 'microsoft'
 
+      - name: setup gradle with dependency caching
+        # Caches Gradle dependencies between runs; combined with retry.sh below
+        # this keeps transient maven download failures from killing a release.
+        uses: gradle/actions/setup-gradle@v6
+
       - name: make gradle wrapper executable
         run: chmod +x ./gradlew
 
       - name: build :${{ matrix.mc }}:build
-        run: ./gradlew :${{ matrix.mc }}:build --stacktrace
+        run: bash .github/scripts/retry.sh ./gradlew :${{ matrix.mc }}:build --stacktrace
 
       - name: publish to modrinth and curseforge
         uses: Kir-Antipov/mc-publish@v3.3
diff --git a/build.gradle b/build.gradle
index 9972fe4..6ea0f99 100644
--- a/build.gradle
+++ b/build.gradle
@@ -31,6 +31,10 @@ repositories {
 	maven { url 'https://maven.terraformersmc.com/releases/' }
 }
 
+// Adds the Modrinth maven and modmenuDependency(), a fallback for when the
+// TerraformersMC maven is unreachable.
+apply from: "${rootDir}/gradle/modrinth-fallback.gradle"
+
 // MC 26+ uses fabric-rendering-v1's transitive deps but rejects ASM coming from
 // annotation processors.
 if (!isLegacy) {
@@ -52,14 +56,14 @@ dependencies {
 
 		modImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
 		modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_api_version}"
-		modImplementation "com.terraformersmc:modmenu:${project.modmenu_version}"
+		modImplementation modmenuDependency(project.modmenu_version)
 		modImplementation("me.shedaniel.cloth:cloth-config-fabric:${project.cloth_config_version}") {
 			exclude(group: 'net.fabricmc.fabric-api')
 		}
 	} else {
 		implementation "net.fabricmc:fabric-loader:${project.loader_version}"
 		implementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_api_version}"
-		implementation "com.terraformersmc:modmenu:${project.modmenu_version}"
+		implementation modmenuDependency(project.modmenu_version)
 		implementation("me.shedaniel.cloth:cloth-config-fabric:${project.cloth_config_version}") {
 			exclude(group: 'net.fabricmc.fabric-api')
 		}
diff --git a/gradle/modrinth-fallback.gradle b/gradle/modrinth-fallback.gradle
new file mode 100644
index 0000000..987dcd0
--- /dev/null
+++ b/gradle/modrinth-fallback.gradle
@@ -0,0 +1,41 @@
+// Fallback for the TerraformersMC maven, which intermittently fails downloads
+// in CI ("Premature end of chunk coded message body"). The Modrinth maven
+// serves the exact same Mod Menu release jars under maven.modrinth coordinates
+// with identical version strings, so when the TerraformersMC coordinate cannot
+// be resolved the build switches to the Modrinth mirror instead of failing.
+//
+// Apply after the project's own repositories block, then declare Mod Menu via
+// modmenuDependency("<version>").
+
+repositories {
+	exclusiveContent {
+		forRepository {
+			maven {
+				name = 'Modrinth'
+				url = 'https://api.modrinth.com/maven'
+			}
+		}
+		// Only maven.modrinth artifacts come from here, and nowhere else — the
+		// other repositories are never queried for the fallback coordinates.
+		filter {
+			includeGroup 'maven.modrinth'
+		}
+	}
+}
+
+ext.modmenuDependency = { String version ->
+	def primary = "com.terraformersmc:modmenu:${version}"
+	try {
+		// Probe the primary coordinate with a detached configuration. Release
+		// versions are cached forever, so once downloaded (or restored from the
+		// CI Gradle cache) this touches no network at all.
+		def probe = configurations.detachedConfiguration(dependencies.create(primary))
+		probe.transitive = false
+		probe.resolve()
+		return primary
+	} catch (Exception e) {
+		logger.warn("Could not resolve ${primary} from the TerraformersMC maven " +
+			"(${e.message}); falling back to maven.modrinth:modmenu:${version}")
+		return "maven.modrinth:modmenu:${version}"
+	}
+}
diff --git a/launchtest/build.gradle b/launchtest/build.gradle
index 49d52e8..8a33a52 100644
--- a/launchtest/build.gradle
+++ b/launchtest/build.gradle
@@ -68,6 +68,10 @@ repositories {
 	maven { url 'https://maven.terraformersmc.com/releases/' }
 }
 
+// Adds the Modrinth maven and modmenuDependency(), a fallback for when the
+// TerraformersMC maven is unreachable.
+apply from: "${rootDir}/gradle/modrinth-fallback.gradle"
+
 // Matches the variant builds: MC 26+ rejects ASM coming from annotation processors.
 if (!isLegacy) {
 	configurations.configureEach {
@@ -107,7 +111,7 @@ dependencies {
 	// mavens; transitive deps are excluded because each fat jar already nests
 	// everything it needs via jar-in-jar.
 	productionRuntimeMods("net.fabricmc.fabric-api:fabric-api:${entry.fabricApi}") { transitive = false }
-	productionRuntimeMods("com.terraformersmc:modmenu:${entry.modmenu}") { transitive = false }
+	productionRuntimeMods(modmenuDependency(entry.modmenu)) { transitive = false }
 	productionRuntimeMods("me.shedaniel.cloth:cloth-config-fabric:${entry.cloth}") { transitive = false }
 
 	if (entry.clientGametest) {