diff --git a/.gitea/workflows/build_and_test.yml b/.gitea/workflows/build_and_test.yml
index fa13a3ce..668c12d6 100644
--- a/.gitea/workflows/build_and_test.yml
+++ b/.gitea/workflows/build_and_test.yml
@@ -174,18 +174,45 @@ jobs:
                  python3 gitea_upload_file.py "$file"
             done
           fi
-  dials-test:
-    name: DIALS test
+  # Artifact-reuse probe: build jfjoch_hdf5_test once here and hand it to dials-test below, instead
+  # of every rocky9 processing job recompiling it from scratch (~12 min each). Once this round-trip
+  # is confirmed working on the PSI Gitea, the xds-* jobs can consume the same artifact the same way.
+  build-hdf5-test:
+    name: Build jfjoch_hdf5_test
     runs-on: jfjoch_rocky9
     steps:
       - uses: actions/checkout@v4
-      - name: Build processing test
+      - name: Build jfjoch_hdf5_test
         shell: bash
         run: |
           mkdir -p build
           cd build
           cmake -G Ninja -DCMAKE_BUILD_TYPE=Release ${{ env.MARCH_CMAKE_FLAGS }} ..
           ninja -j16 jfjoch_hdf5_test
+      # Gitea 1.27 speaks the v4 artifact protocol, but stock actions/upload-artifact@v4 treats any
+      # non-github.com server as GHES and aborts with GHESNotSupportedError. The christopherhx fork
+      # (mirrored under gitea.psi.ch/actions) drops that check; pinning upstream @v3 also works.
+      - name: Upload jfjoch_hdf5_test
+        uses: https://gitea.psi.ch/actions/gitea-upload-artifact@v4
+        with:
+          name: jfjoch_hdf5_test-rocky9
+          path: build/tools/jfjoch_hdf5_test
+          retention-days: 1
+  dials-test:
+    name: DIALS test
+    runs-on: jfjoch_rocky9
+    needs: build-hdf5-test
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download jfjoch_hdf5_test
+        uses: https://gitea.psi.ch/actions/gitea-download-artifact@v4
+        with:
+          name: jfjoch_hdf5_test-rocky9
+          path: build/tools
+      # Artifacts are zipped, which discards the executable bit -- restore it before running.
+      - name: Restore executable bit
+        shell: bash
+        run: chmod +x build/tools/jfjoch_hdf5_test
       - name: Run DIALS processing on legacy format
         shell: bash
         run: |