diff --git a/Dockerfile b/Dockerfile
index e906b8f..7d70267 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM registry.bstein.dev/bstein/python:3.12-slim
+FROM registry.bstein.dev/bstein/python:3.12-slim AS base
 
 ENV PYTHONDONTWRITEBYTECODE=1 \
     PYTHONUNBUFFERED=1
@@ -9,5 +9,11 @@ RUN pip install --no-cache-dir -r /app/requirements.txt
 
 COPY atlasbot /app/atlasbot
 
+FROM base AS test
+COPY requirements-dev.txt /app/requirements-dev.txt
+RUN pip install --no-cache-dir -r /app/requirements-dev.txt
+COPY tests /app/tests
+
+FROM base AS runtime
 EXPOSE 8090
 CMD ["python", "-m", "atlasbot.main"]
diff --git a/Jenkinsfile b/Jenkinsfile
index 8c795d5..3daa799 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -77,29 +77,6 @@ spec:
         checkout scm
       }
     }
-    stage('Unit tests') {
-      steps {
-        container('tester') {
-          sh '''
-            set -euo pipefail
-            python -m pip install --no-cache-dir -r requirements.txt -r requirements-dev.txt
-            python -m ruff check atlasbot --select C90,PLR
-            mkdir -p build
-            python -m slipcover --json --out build/coverage.json --source atlasbot --fail-under 90 -m pytest -q --junitxml build/junit.xml
-          '''
-        }
-      }
-    }
-    stage('Publish test metrics') {
-      steps {
-        container('tester') {
-          sh '''
-            set -euo pipefail
-            python scripts/publish_test_metrics.py
-          '''
-        }
-      }
-    }
     stage('Prep toolchain') {
       steps {
         container('builder') {
@@ -142,6 +119,33 @@ spec:
         }
       }
     }
+    stage('Unit tests') {
+      steps {
+        container('builder') {
+          sh '''
+            set -euo pipefail
+            mkdir -p build
+            docker buildx build --platform linux/arm64 --target test --load -t atlasbot-test .
+            docker run --rm -v "$PWD/build:/out" atlasbot-test \
+              python -m ruff check atlasbot --select C90,PLR
+            docker run --rm -v "$PWD/build:/out" atlasbot-test \
+              python -m slipcover --json --out /out/coverage.json --source atlasbot --fail-under 90 \
+              -m pytest -q --junitxml /out/junit.xml
+          '''
+        }
+      }
+    }
+    stage('Publish test metrics') {
+      steps {
+        container('builder') {
+          sh '''
+            set -euo pipefail
+            docker run --rm -v "$PWD/build:/out" atlasbot-test \
+              python scripts/publish_test_metrics.py
+          '''
+        }
+      }
+    }
     stage('Build & push image') {
       steps {
         container('builder') {
@@ -149,6 +153,7 @@ spec:
             set -euo pipefail
             VERSION_TAG=$(cut -d= -f2 build.env)
             docker buildx build --platform linux/arm64 \
+              --target runtime \
               --tag registry.bstein.dev/bstein/atlasbot:${VERSION_TAG} \
               --tag registry.bstein.dev/bstein/atlasbot:latest \
               --push .