diff --git a/.github/scripts/run_case_optimization.sh b/.github/scripts/run_case_optimization.sh
index 21b6ff0b6f..bd54aedc05 100755
--- a/.github/scripts/run_case_optimization.sh
+++ b/.github/scripts/run_case_optimization.sh
@@ -13,13 +13,6 @@ if [ "$job_device" = "gpu" ] && [ "$ngpus" -eq 0 ]; then
     ngpus=1
 fi
 
-# Verify the venv Python interpreter exists (created by ./mfc.sh build)
-if [ ! -x build/venv/bin/python3 ]; then
-    echo "ERROR: build/venv/bin/python3 not found."
-    echo "The MFC build venv may not have been created. Was the pre-build step successful?"
-    exit 1
-fi
-
 benchmarks=(
     benchmarks/5eq_rk3_weno3_hllc/case.py
     benchmarks/viscous_weno5_sgb_acoustic/case.py
@@ -28,6 +21,24 @@ benchmarks=(
     benchmarks/igr/case.py
 )
 
+# For Frontier/Frontier AMD: deps were fetched on the login node via --deps-only;
+# build case-optimized binaries here on the compute node before running.
+# For Phoenix: prebuild-case-optimization.sh already built everything in a prior SLURM job.
+# Frontier Cray: -j 1 to work around CCE 19.0.0 IPA SIGSEGV
+build_jobs=8
+if [ "$job_cluster" = "frontier" ]; then
+    build_jobs=1
+fi
+
+if [ "$job_cluster" != "phoenix" ]; then
+    echo "=== Building case-optimized binaries on compute node ==="
+    for case in "${benchmarks[@]}"; do
+        echo "--- Building: $case ---"
+        ./mfc.sh build -i "$case" --case-optimization $gpu_opts -j $build_jobs
+    done
+    echo "=== All case-optimized binaries built ==="
+fi
+
 passed=0
 failed=0
 failed_cases=""
diff --git a/.github/workflows/bench.yml b/.github/workflows/bench.yml
index 7ce02c1e3f..d39831730d 100644
--- a/.github/workflows/bench.yml
+++ b/.github/workflows/bench.yml
@@ -68,7 +68,7 @@ jobs:
             flag: f
             device: gpu
             interface: acc
-            build_script: "bash .github/workflows/frontier/build.sh gpu acc bench"
+            build_script: "bash .github/workflows/frontier/build.sh gpu acc"
           - cluster: frontier
             name: Oak Ridge | Frontier (CCE)
             group: phoenix
@@ -76,7 +76,7 @@ jobs:
             flag: f
             device: gpu
             interface: omp
-            build_script: "bash .github/workflows/frontier/build.sh gpu omp bench"
+            build_script: "bash .github/workflows/frontier/build.sh gpu omp"
           - cluster: frontier_amd
             name: Oak Ridge | Frontier (AMD)
             group: phoenix
@@ -84,7 +84,7 @@ jobs:
             flag: famd
             device: gpu
             interface: omp
-            build_script: "bash .github/workflows/frontier_amd/build.sh gpu omp bench"
+            build_script: "bash .github/workflows/frontier_amd/build.sh gpu omp"
     continue-on-error: ${{ matrix.cluster == 'frontier' || matrix.cluster == 'frontier_amd' }}
     runs-on:
       group: ${{ matrix.group }}
@@ -103,7 +103,7 @@ jobs:
           ref: master
           path: master
 
-      - name: Setup & Build
+      - name: Fetch Dependencies
         if: matrix.build_script != ''
         timeout-minutes: 150
         run: |
diff --git a/.github/workflows/common/bench.sh b/.github/workflows/common/bench.sh
index 66d77cfd99..9522e3a043 100644
--- a/.github/workflows/common/bench.sh
+++ b/.github/workflows/common/bench.sh
@@ -21,19 +21,24 @@ if [ "$job_cluster" = "phoenix" ]; then
     trap 'rm -rf "$currentdir" || true' EXIT
 fi
 
-# --- Build (if not pre-built on login node) ---
-# Phoenix builds inside SLURM; Frontier pre-builds via build.sh on the login node.
+# --- Build ---
+# Phoenix builds everything inside SLURM (no login-node build step).
+# Frontier/Frontier AMD: deps already fetched on login node via --deps-only;
+# source code is built here on the compute node.
 # Phoenix: always nuke stale builds (heterogeneous compute nodes → ISA mismatch risk).
 if [ "$job_cluster" = "phoenix" ]; then
     source .github/scripts/clean-build.sh
     clean_build
 fi
 
-if [ ! -d "build" ]; then
-    source .github/scripts/retry-build.sh
-    retry_build ./mfc.sh build -j $n_jobs $build_opts || exit 1
+# Frontier Cray: -j 1 to work around CCE 19.0.0 IPA SIGSEGV
+if [ "$job_cluster" = "frontier" ]; then
+    n_jobs=1
 fi
 
+source .github/scripts/retry-build.sh
+retry_build ./mfc.sh build -j $n_jobs $build_opts || exit 1
+
 # --- Bench cluster flag ---
 if [ "$job_cluster" = "phoenix" ]; then
     bench_cluster="phoenix-bench"
diff --git a/.github/workflows/common/test.sh b/.github/workflows/common/test.sh
index e155fd48f8..2733235549 100644
--- a/.github/workflows/common/test.sh
+++ b/.github/workflows/common/test.sh
@@ -21,29 +21,35 @@ if [ "$job_cluster" = "phoenix" ]; then
     trap 'rm -rf "$currentdir" || true' EXIT
 fi
 
-# --- Build (if not pre-built on login node) ---
-# Phoenix builds inside SLURM; Frontier pre-builds via build.sh on the login node.
-# Phoenix builds inside SLURM on heterogeneous compute nodes — always start fresh
-# to avoid SIGILL from stale binaries compiled on a different microarchitecture.
+# --- Build ---
+# Phoenix builds everything inside SLURM (no login-node build step).
+# Frontier/Frontier AMD: deps already fetched on login node via --deps-only;
+# source code is built here on the compute node.
+# Phoenix: always start fresh to avoid SIGILL from stale binaries compiled
+# on a different microarchitecture.
 if [ "$job_cluster" = "phoenix" ]; then
     source .github/scripts/clean-build.sh
     clean_build
 fi
 
-if [ ! -d "build" ]; then
-    source .github/scripts/retry-build.sh
+source .github/scripts/retry-build.sh
 
-    # Phoenix: smoke-test the syscheck binary to catch architecture mismatches
-    # (SIGILL from binaries compiled on a different compute node).
-    validate_cmd=""
-    if [ "$job_cluster" = "phoenix" ]; then
-        validate_cmd='syscheck_bin=$(find build/install -name syscheck -type f 2>/dev/null | head -1); [ -z "$syscheck_bin" ] || "$syscheck_bin" > /dev/null 2>&1'
-    fi
+# Phoenix: smoke-test the syscheck binary to catch architecture mismatches
+# (SIGILL from binaries compiled on a different compute node).
+validate_cmd=""
+if [ "$job_cluster" = "phoenix" ]; then
+    validate_cmd='syscheck_bin=$(find build/install -name syscheck -type f 2>/dev/null | head -1); [ -z "$syscheck_bin" ] || "$syscheck_bin" > /dev/null 2>&1'
+fi
 
-    RETRY_VALIDATE_CMD="$validate_cmd" \
-        retry_build ./mfc.sh test -v --dry-run -j 8 $build_opts || exit 1
+# Frontier Cray: -j 1 to work around CCE 19.0.0 IPA SIGSEGV
+build_jobs=8
+if [ "$job_cluster" = "frontier" ]; then
+    build_jobs=1
 fi
 
+RETRY_VALIDATE_CMD="$validate_cmd" \
+    retry_build ./mfc.sh test -v --dry-run -j $build_jobs $build_opts || exit 1
+
 # --- GPU detection and thread count ---
 device_opts=""
 rdma_opts=""
diff --git a/.github/workflows/frontier/build.sh b/.github/workflows/frontier/build.sh
index 5bd40999d7..cd289ef074 100644
--- a/.github/workflows/frontier/build.sh
+++ b/.github/workflows/frontier/build.sh
@@ -14,7 +14,6 @@ esac
 
 job_device=$1
 job_interface=$2
-run_bench=$3
 source .github/scripts/gpu-opts.sh
 build_opts="$gpu_opts"
 
@@ -24,8 +23,4 @@ source .github/scripts/clean-build.sh
 clean_build
 
 source .github/scripts/retry-build.sh
-if [ "$run_bench" == "bench" ]; then
-    retry_build ./mfc.sh build -j 8 $build_opts || exit 1
-else
-    retry_build ./mfc.sh test -v -a --dry-run $([ "$cluster_name" = "frontier" ] && echo "--rdma-mpi") -j 8 $build_opts || exit 1
-fi
+retry_build ./mfc.sh build --deps-only -j 8 $build_opts || exit 1
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 90ad965c52..d40a44f04f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -400,12 +400,12 @@ jobs:
             echo "Coverage cache: none available — full test suite will run"
           fi
 
-      - name: Build (login node)
+      - name: Fetch Dependencies
         if:   matrix.cluster != 'phoenix'
         timeout-minutes: 60
         run:  bash .github/workflows/${{ matrix.cluster }}/build.sh ${{ matrix.device }} ${{ matrix.interface }}
 
-      - name: Test
+      - name: Build & Test
         run:  bash .github/scripts/submit-slurm-job.sh .github/workflows/common/test.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }} ${{ matrix.shard }}
 
       - name: Cancel SLURM Jobs
@@ -486,15 +486,20 @@ jobs:
       - name: Clean stale output files
         run:  rm -f *.out
 
+      - name: Fetch Dependencies
+        if:   matrix.cluster != 'phoenix'
+        run:  bash .github/workflows/${{ matrix.cluster }}/build.sh ${{ matrix.device }} ${{ matrix.interface }}
+
       - name: Pre-Build (SLURM)
         if:   matrix.cluster == 'phoenix'
         run:  bash .github/scripts/submit-slurm-job.sh .github/scripts/prebuild-case-optimization.sh cpu ${{ matrix.interface }} ${{ matrix.cluster }}
 
-      - name: Pre-Build (login node)
+      - name: Build & Run Case-Optimization Tests
         if:   matrix.cluster != 'phoenix'
-        run:  bash .github/scripts/prebuild-case-optimization.sh ${{ matrix.cluster }} ${{ matrix.device }} ${{ matrix.interface }}
+        run:  bash .github/scripts/submit-slurm-job.sh .github/scripts/run_case_optimization.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }}
 
       - name: Run Case-Optimization Tests
+        if:   matrix.cluster == 'phoenix'
         run:  bash .github/scripts/submit-slurm-job.sh .github/scripts/run_case_optimization.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }}
 
       - name: Cancel SLURM Jobs
diff --git a/toolchain/mfc/build.py b/toolchain/mfc/build.py
index d6daf97bb6..9fed43c271 100644
--- a/toolchain/mfc/build.py
+++ b/toolchain/mfc/build.py
@@ -552,6 +552,12 @@ def __build_target(target: typing.Union[MFCTarget, str], case: input.MFCInputFil
 
     history.add(target.name)
 
+    # Dependencies are pinned to fixed versions. If already configured
+    # (built & installed by a prior --deps-only step), skip entirely
+    # to avoid re-entering the superbuild (which may access the network).
+    if target.isDependency and target.is_configured(case):
+        return
+
     for dep in target.requires.compute():
         # If we have already built and installed this target,
         # do not do so again. This can be inferred by whether
@@ -594,6 +600,25 @@ def build(targets=None, case: input.MFCInputFile = None, history: typing.Set[str
     case = case or input.load(ARG("input"), ARG("--"), {})
     case.validate_params()
 
+    if ARG("deps_only", False) and len(history) == 0:
+        all_deps = set()
+        for t in targets:
+            resolved = get_target(t)
+            for dep in resolved.requires.compute():
+                all_deps.add(dep)
+
+        cons.print(f"[bold]Fetch Dependencies | {format_list_to_string([d.name for d in all_deps], 'magenta', 'None')}[/bold]")
+        cons.print(no_indent=True)
+
+        if not all_deps:
+            cons.print("[yellow]No dependencies to build for the requested targets.[/yellow]")
+            return
+
+        for dep in all_deps:
+            __build_target(dep, case, history)
+
+        return
+
     if len(history) == 0:
         cons.print(__generate_header(case, targets))
         cons.print(no_indent=True)
diff --git a/toolchain/mfc/cli/commands.py b/toolchain/mfc/cli/commands.py
index 85aab95031..e98003aa74 100644
--- a/toolchain/mfc/cli/commands.py
+++ b/toolchain/mfc/cli/commands.py
@@ -134,6 +134,13 @@
             default=False,
             dest="case_optimization",
         ),
+        Argument(
+            name="deps-only",
+            help="Only fetch and build dependencies, do not build MFC targets.",
+            action=ArgAction.STORE_TRUE,
+            default=False,
+            dest="deps_only",
+        ),
     ],
     examples=[
         Example("./mfc.sh build", "Build all default targets (CPU)"),