Fix CI: add flashinfer --download-cubin to install dependencies (#18887)

Co-authored-by: Liangsheng Yin <lsyincs@gmail.com>

scripts/ci/cuda/ci_download_flashinfer_cubin.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+# Download flashinfer cubins if the local set is incomplete.
+#
+# The flashinfer-cubin pip package may not include cubins for newer architectures
+# (e.g. sm_100, sm_120) due to PyPI size limits. This script checks the local
+# cubin status against the flashinfer artifact repository and downloads any
+# missing files.
+set -euxo pipefail
+
+CUBIN_STATUS=$(FLASHINFER_LOGGING_LEVEL=warning python3 -c "
+from flashinfer.artifacts import get_artifacts_status
+status = get_artifacts_status()
+total = len(status)
+downloaded = sum(1 for _, exists in status if exists)
+print(f'{downloaded}/{total}')
+" 2>/dev/null) || CUBIN_STATUS="unknown"
+
+echo "Flashinfer cubin status: ${CUBIN_STATUS}"
+
+if echo "$CUBIN_STATUS" | grep -qE '^[0-9]+/[0-9]+$'; then
+    CUBIN_DOWNLOADED="${CUBIN_STATUS%/*}"
+    CUBIN_TOTAL="${CUBIN_STATUS#*/}"
+    if [ "$CUBIN_DOWNLOADED" = "$CUBIN_TOTAL" ] && [ "$CUBIN_TOTAL" != "0" ]; then
+        echo "All flashinfer cubins already present (${CUBIN_STATUS}), skipping download"
+    else
+        echo "Cubins incomplete (${CUBIN_STATUS}), downloading..."
+        FLASHINFER_LOGGING_LEVEL=warning python3 -m flashinfer --download-cubin
+    fi
+else
+    echo "Could not determine cubin status, downloading as fallback..."
+    FLASHINFER_LOGGING_LEVEL=warning python3 -m flashinfer --download-cubin
+fi

scripts/ci/cuda/ci_install_dependency.sh

@@ -289,6 +289,9 @@ if [ "$FLASHINFER_INSTALLED" = false ]; then
     exit 1
 fi
 
+# Download flashinfer cubins if the local set is incomplete
+bash "${SCRIPT_DIR}/ci_download_flashinfer_cubin.sh"
+
 # Show current packages
 $PIP_CMD list
 python3 -c "import torch; print(torch.version.cuda)"