diff --git a/.github/workflows/nightly-build.yml b/.github/workflows/nightly-build.yml
index d957cdd..9ab69af 100644
--- a/.github/workflows/nightly-build.yml
+++ b/.github/workflows/nightly-build.yml
@@ -68,6 +68,18 @@ jobs:
 
       - uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4
 
+      # What a build downloads and would download again tomorrow: the packages
+      # the ISO's offline mirror is made of (the build prunes the ones it no
+      # longer needs) and the test container's own. Skipped, not failed, on a
+      # runner without a cache volume.
+      - name: Package cache (Namespace)
+        continue-on-error: true
+        uses: namespacelabs/nscloud-cache-action@c5f8dab7560444c4bf8dbc64f1b203431873c547 # v1.6.1
+        with:
+          path: |
+            ~/.cache/omarchy
+            ~/.cache/omarchy-ci
+
       - name: Build the edge ISO
         run: NO_BOOT_OFFER=1 ./bin/omarchy-iso-make --edge
 
@@ -76,7 +88,9 @@ jobs:
       - name: Install unattended, boot the installed system, seal it
         run: |
           sudo chmod 0666 /dev/kvm
+          mkdir -p ~/.cache/omarchy-ci/pacman
           docker run --rm --device /dev/kvm -v "$PWD:/w" -w /w \
+            -v "$HOME/.cache/omarchy-ci/pacman:/var/cache/pacman/pkg" \
             -e OMARCHY_INTEGRATION_DISK_CACHE=none \
             archlinux:latest bash -euo pipefail -c '
               # pacman 7 fails every sync on a kernel without Landlock, which