diff --git a/packages/cli/src/commands/manifest/scripts/maven-extension/build-jar.sh b/packages/cli/src/commands/manifest/scripts/maven-extension/build-jar.sh
index eeaef2f67..5ca607bd8 100755
--- a/packages/cli/src/commands/manifest/scripts/maven-extension/build-jar.sh
+++ b/packages/cli/src/commands/manifest/scripts/maven-extension/build-jar.sh
@@ -5,6 +5,18 @@
 set -euo pipefail
 
 here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-( cd "$here" && ./mvnw -q --batch-mode package )
+
+# Keep the downloaded artifacts and the Maven distribution out of the developer's ~/.m2. The path is
+# stable so the plugin closure stays cached between runs; point SOCKET_CLI_MAVEN_HOME elsewhere for a
+# cold build.
+tmp_root="${TMPDIR:-/tmp}"
+maven_home="${SOCKET_CLI_MAVEN_HOME:-${tmp_root%/}/socket-cli-maven-home}"
+mkdir -p "$maven_home"
+
+(
+  cd "$here"
+  MAVEN_USER_HOME="$maven_home" ./mvnw -q --batch-mode \
+    -Dmaven.repo.local="$maven_home/repository" package
+)
 cp -f "$here/target/coana-maven-extension.jar" "$here/coana-maven-extension.jar"
 echo "Coana Maven extension jar: $here/coana-maven-extension.jar"