diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
index 7358a84..469a82e 100644
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@@ -38,6 +38,10 @@ jobs:
           echo "IMAGE_REGISTRY=${REGISTRY_HOST}/${OWNER_LOWER,,}" >> ${GITHUB_ENV}
           echo "IMAGE_NAME=${NAME_LOWER,,}" >> ${GITHUB_ENV}
 
+          # Aktuelles Tagesdatum direkt von der Runner-VM beziehen (UTC)
+          echo "DATE_TAG=$(date -u +'%Y%m%d')" >> ${GITHUB_ENV}
+          echo "BUILD_DATE_ISO=$(date -u +'%Y-%m-%dT%H:%M:%SZ')" >> ${GITHUB_ENV}
+
       - name: Checkout
         uses: actions/checkout@v7.0.1
 
@@ -51,18 +55,19 @@ jobs:
           images: ${{ env.IMAGE_REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
             type=raw,value=${{ env.DEFAULT_TAG }},enable=${{ github.ref_name == 'main' }}
-            type=raw,value=${{ env.DEFAULT_TAG }}.{{date 'YYYYMMDD'}},enable=${{ github.ref_name == 'main' }}
-            type=raw,value={{date 'YYYYMMDD'}},enable=${{ github.ref_name == 'main' }}
+            type=raw,value=${{ env.DEFAULT_TAG }}.${{ env.DATE_TAG }},enable=${{ github.ref_name == 'main' }}
+            type=raw,value=${{ env.DATE_TAG }},enable=${{ github.ref_name == 'main' }}
             type=raw,value=test-{{branch}},enable=${{ github.ref_name != 'main' && github.event_name != 'pull_request' }}
             type=ref,event=pr,prefix=test-pr-
           labels: |
-            org.opencontainers.image.created={{date 'YYYY-MM-DDTHH:mm:ssZ'}}
+            org.opencontainers.image.created=${{ env.BUILD_DATE_ISO }}
             org.opencontainers.image.description=${{ env.IMAGE_DESC }}
             org.opencontainers.image.documentation=${{ github.server_url }}/${{ github.repository }}
             org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
             org.opencontainers.image.title=${{ env.IMAGE_NAME }}
             org.opencontainers.image.url=${{ github.server_url }}/${{ github.repository }}
             org.opencontainers.image.vendor=${{ github.repository_owner }}
+            org.opencontainers.image.version=${{ env.DEFAULT_TAG }}.${{ env.DATE_TAG }}
             containers.bootc=1
             ostree.bootable=1
 
@@ -85,6 +90,10 @@ jobs:
           labels: ${{ steps.metadata.outputs.labels }}
           oci-mediatypes: true
           compression: zstd
+          # Aktiviert die Chunk-Map für zstd:chunked Range-Requests
+          build-args: |
+            BUILDKIT_OCI_MEDIATYPE=true
+          output: type=registry,push=${{ github.event_name != 'pull_request' }},oci-mediatypes=true,compression=zstd,compression-args=binary-path=/usr/bin/go-zstd-chunked
 
       - name: Install envsubst dependencies
         if: github.event_name != 'pull_request' && github.ref_name == 'main'