diff --git a/.github/workflows/ci-benchmark.yml b/.github/workflows/ci-benchmark.yml
index 374ebbd69..92ebdafa8 100644
--- a/.github/workflows/ci-benchmark.yml
+++ b/.github/workflows/ci-benchmark.yml
@@ -186,6 +186,115 @@ jobs:
       - name: Mark phase — python setup done
         run: echo "python_setup=$(date +%s)" >> /tmp/benchmark-clock
 
+      # ── Julia Setup ──────────────────────────────────────────
+      # Cold builds (force_full_rebuild) delete _freeze, so Julia/Heatmap.qmd
+      # and friends re-execute during the babelquarto render — benchmark run
+      # 38109155362 died there with "Ensuring an updated julia server
+      # environment failed" because no Julia was installed.  Mirror the
+      # setup from quarto-publish-update-cache.yml: Julia + a pinned
+      # QuartoNotebookRunner environment (QUARTO_JULIA_PROJECT skips Quarto's
+      # ensureQuartoNotebookRunnerEnvironment, which needs network+Pkg.update
+      # at render time) + the tutorial project env.
+      - name: Set up Julia
+        uses: julia-actions/setup-julia@v3
+        with:
+          version: '1'
+
+      - name: Cache Julia packages
+        uses: actions/cache/restore@v6
+        with:
+          path: ~/.julia
+          key: julia-packages-${{ runner.os }}-${{ hashFiles('Julia/Project.toml') }}
+          restore-keys: |
+            julia-packages-${{ runner.os }}-
+
+      - name: Install Julia packages
+        run: |
+          # Find the QuartoNotebookRunner version required by this Quarto installation.
+          # Quarto bundles its own julia-engine Project.toml that pins an exact QNR version.
+          JULIA_ENGINE_PROJ=$(find /opt/quarto -name "Project.toml" -path "*/julia-engine/*" 2>/dev/null | head -1)
+          QNR_VERSION=""
+          if [ -n "$JULIA_ENGINE_PROJ" ]; then
+            QNR_VERSION=$(grep -oP 'QuartoNotebookRunner = "=([^"]+)"' "$JULIA_ENGINE_PROJ" \
+              | grep -oP '[0-9]+\.[0-9]+\.[0-9]+' || true)
+            echo "Quarto requires QuartoNotebookRunner=${QNR_VERSION}"
+          fi
+
+          # Create a dedicated QNR environment.  Setting QUARTO_JULIA_PROJECT to this
+          # path tells Quarto to skip ensureQuartoNotebookRunnerEnvironment (which calls
+          # Pkg.update() and needs network at render time) and simply verify QNR loads.
+          QNR_ENV="${HOME}/.julia/environments/quarto-julia-env"
+          mkdir -p "${QNR_ENV}"
+
+          if [ -n "$QNR_VERSION" ]; then
+            julia --project="${QNR_ENV}" -e "
+              using Pkg
+              Pkg.add(name=\"QuartoNotebookRunner\", version=\"${QNR_VERSION}\")
+              Pkg.instantiate()
+              using QuartoNotebookRunner
+              println(\"QuartoNotebookRunner \$(pkgversion(QuartoNotebookRunner)) ready\")
+            "
+          else
+            julia --project="${QNR_ENV}" -e '
+              using Pkg
+              Pkg.add("QuartoNotebookRunner")
+              Pkg.instantiate()
+              using QuartoNotebookRunner
+              println("QuartoNotebookRunner $(pkgversion(QuartoNotebookRunner)) ready")
+            '
+          fi
+
+          # Export so the render step can pick it up.
+          echo "QUARTO_JULIA_PROJECT=${QNR_ENV}" >> "$GITHUB_ENV"
+
+          # Pre-instantiate the tutorial project environment (Julia/Project.toml).
+          # QNR workers use JULIA_PROJECT=@. and cd into the notebook directory,
+          # so they automatically pick up Julia/Project.toml for CairoMakie etc.
+          julia --project=Julia -e '
+            using Pkg
+            Pkg.resolve()
+            Pkg.instantiate()
+            using CairoMakie, DataFrames, Statistics
+            println("Tutorial packages ready")
+          '
+
+      # Pre-render Julia notebooks to avoid OOM during the R-heavy main render.
+      # Also REQUIRED for correctness: without this step babelquarto executes
+      # Julia qmds inline in its temp dir and the julia-engine JSON handshake
+      # fails ("SyntaxError: Unexpected end of JSON input" — CI run
+      # 38114723635).  Pre-rendering freezes Julia/*.qmd into the workspace
+      # _freeze so babelquarto never executes them.
+      - name: Create temporary directory
+        run: |
+          sudo mkdir -p ${{ env.TMP_DIR }}
+          sudo chown -R $USER:$USER ${{ env.TMP_DIR }}
+
+      - name: Pre-render Julia notebooks
+        env:
+          QUARTO_JULIA_PROJECT: ${{ env.QUARTO_JULIA_PROJECT }}
+          TMPDIR: ${{ env.TMP_DIR }}
+          TMP: ${{ env.TMP_DIR }}
+          TEMP: ${{ env.TMP_DIR }}
+        run: |
+          echo "Pre-rendering Julia tutorials..."
+          failed=0
+          for qmd in Julia/*.qmd; do
+            echo "  → $qmd"
+            if quarto render "$qmd" 2>&1; then
+              echo "  ✓ OK: $qmd"
+            else
+              echo "  ✗ Failed: $qmd"
+              failed=1
+            fi
+          done
+          julia_log="${HOME}/.cache/quarto/julia/julia_server_log.txt"
+          if [ -f "$julia_log" ]; then
+            echo "=== QNR server log ==="
+            tail -50 "$julia_log"
+            echo "======================"
+          fi
+          [ $failed -eq 0 ] || exit 1
+
       # ── Render pipeline (mirrors quarto-publish-update-cache.yml) ──
       - name: Pre-render all non-frozen QMD files
         env: