diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index 80cb3e71..f361cfe5 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -6,17 +6,30 @@
 		},
 		"ghcr.io/devcontainers/features/docker-in-docker:2": {}
 	},
+	"postStartCommand": "sudo apt-get update && sudo apt-get install -y fontconfig && sudo apt-get clean",
+	"postAttachCommand": "nvm install 21.6.1",
 	"customizations": {
 		"vscode": {
 			"extensions": [
-				"ryanluker.vscode-coverage-gutters"
+				"ryanluker.vscode-coverage-gutters",
+				"SonarSource.sonarlint-vscode"
 			],
 			"settings": {
 				"editor.renderWhitespace": "all",
 				"coverage-gutters.coverageFileNames": [
 					"jacocoTestReport.xml"
 				],
-				"coverage-gutters.showLineCoverage": true
+				"coverage-gutters.showLineCoverage": true,
+				"sonarlint.pathToNodeExecutable": "/usr/local/share/nvm/versions/node/v21.6.1/bin/node",
+				"sonarlint.output.showVerboseLogs": true,
+				"sonarlint.analyzerProperties": {
+					"sonar.java.source": "21"
+				},
+				"search.exclude": {
+					"gradlew": true,
+					"gradlew.bat": true,
+					"gradle/": true
+				}
 			}
 		}
 	}
diff --git a/.github/workflows/gradle.yml b/.github/workflows/gradle.yml
index 91fa1e8a..13cc9da6 100644
--- a/.github/workflows/gradle.yml
+++ b/.github/workflows/gradle.yml
@@ -47,10 +47,9 @@ jobs:
       with:
         distribution: temurin
         java-version: ${{ matrix.java-version }}
-        cache: gradle
 
     - name: run tests && build project
-      run: ./gradlew build --no-daemon
+      run: ./gradlew build --no-daemon --warning-mode all
 
     - uses: mikepenz/action-junit-report@v4.0.3
       if: always()
diff --git a/Dockerfile b/Dockerfile
index 8795bee9..e13605fc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM gradle:8.5.0-jdk21 AS build
+FROM gradle:8.6.0-jdk21 AS build
 
 COPY --chown=gradle:gradle . /home/gradle/tla-frontend
 WORKDIR /home/gradle/tla-frontend
@@ -7,7 +7,8 @@ RUN gradle installAssets bootJar --no-daemon
 
 FROM openjdk:23-jdk-slim-bookworm
 
-RUN mkdir /app; apt-get update && apt-get install -y fontconfig
+RUN mkdir /app; apt-get update && apt-get install -y fontconfig \
+  && apt-get clean
 WORKDIR /app
 
 COPY --from=build /home/gradle/tla-frontend/build/libs/*.jar /app/tla-web-frontend.jar
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 1af9e093..a80b22ce 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/gradlew.bat b/gradlew.bat
index 6689b85b..7101f8e4 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -43,11 +43,11 @@ set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
 if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -57,11 +57,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail