deploy: per-host CUDA kernel choice; benjy runs the loop kernel

The matrix gains `cuda_kernel` (rendered into miner.env as
MINER_CUDA_KERNEL) next to `kernel`, the id validate asserts. benjy's
4090 measured +1.7% on the loop kernel (727-736 vs 716-718 MH/s, parity
200/200), so it runs loop / cuda-loop; quadbrat (-1.8%) and beast
(-3.4%) stay on unrolled / cuda. A rollback to a binary that predates
the switch is safe: it ignores the variable.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ue5ZZm1Hiv5zPnucykKKuF

.gitea/workflows/deploy.yaml

@@ -88,17 +88,24 @@ jobs:
           # `kernel` is the kernel id validate expects on the per-device metric:
           # cuda (engine-cuda, #3) on every NVIDIA host once the build carries
           # the fat binary; u64 would mean the miner silently fell back to wgpu.
+          # `cuda_kernel` selects the kernel entry (MINER_CUDA_KERNEL, #29):
+          # unrolled is the default; loop measured +1.7% on the 4090 and
+          # -1.8% / -3.4% on the 3060 / 5090 (2026-09-14), so only benjy runs
+          # it. `kernel` must be the id that choice reports: cuda or cuda-loop.
           - host: benjy.hanzalova.internal
             node: bob.hanzalova.internal
             gpu_devices: "1"        # 1x RTX 4090 (sm_89); reference card for #2
-            kernel: cuda
+            cuda_kernel: loop
+            kernel: cuda-loop
           - host: quadbrat.hanzalova.internal
             node: bob.hanzalova.internal
             gpu_devices: "1"        # 1x RTX 3060 (sm_86)
+            cuda_kernel: unrolled
             kernel: cuda
           - host: beast.hanzalova.internal
             node: bob.hanzalova.internal
             gpu_devices: "2"        # 2x RTX 5090 (sm_120)
+            cuda_kernel: unrolled
             kernel: cuda
     steps:
       - uses: actions/checkout@v4
@@ -146,6 +153,7 @@ jobs:
         if: ${{ github.event.inputs.mode != 'validate' }}
         env:
           GPU_DEVICES: ${{ matrix.gpu_devices }}
+          CUDA_KERNEL: ${{ matrix.cuda_kernel }}
         run: |
           set -euo pipefail
           SSHOPTS="-i $HOME/.ssh/id_gitea_ci -o StrictHostKeyChecking=accept-new"
@@ -210,6 +218,7 @@ jobs:
           t = pathlib.Path("deploy/miner.env.tmpl").read_text()
           t = t.replace("{{QUANTUS_NODE_ADDR}}", os.environ["NODE_ADDR"])
           t = t.replace("{{QUANTUS_GPU_DEVICES}}", os.environ["GPU_DEVICES"])
+          t = t.replace("{{MINER_CUDA_KERNEL}}", os.environ["CUDA_KERNEL"])
           pathlib.Path("miner.env").write_text(t)
           PY
           push --chown=root:quantus-miner --chmod=F0640 \

deploy/miner.env.tmpl

@@ -4,3 +4,5 @@
 # from the node host as separate 0640 files.
 QUANTUS_NODE_ADDR={{QUANTUS_NODE_ADDR}}
 QUANTUS_GPU_DEVICES={{QUANTUS_GPU_DEVICES}}
+# Kernel entry in the CUDA engine: unrolled (mining_main) or loop (mining_loop), quantus/miner#29.
+MINER_CUDA_KERNEL={{MINER_CUDA_KERNEL}}