[TEST ONLY] Add cudf-java JAR smoke tests

java/ci/README.md

@@ -90,6 +90,15 @@ per-entry artifact. The separate `java-gather` job downloads them (with
 `merge-multiple: true`, so all subdirs land in a single parent dir), runs
 Step 3, and uploads the combined `cudf_java_maven_repo` artifact.
 
+### Step 4 - Smoke tests (optional, local)
+
+After assembling a Maven-repo tree, run the packaging smoke suite under
+[`java/smoke-tests/`](../smoke-tests/README.md):
+
+```bash
+./java/smoke-tests/bin/run.sh --maven-repo-dir /tmp/maven-repo
+```
+
 ## Legacy: manual Dockerfile.rocky build (obsolete)
 
 > The `java/ci/Dockerfile.rocky` + `java/ci/build-in-docker.sh` flow below is the

java/smoke-tests/.gitignore

@@ -0,0 +1,5 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-License-Identifier: Apache-2.0
+
+.cache/
+target/

java/smoke-tests/README.md

@@ -0,0 +1,81 @@
+# cudf-java smoke tests
+
+Smoke published `ai.rapids:cudf` classifier JARs under a Maven Central-style
+classpath (cudf + slf4j only).
+
+## Quick start
+
+Exactly one source mode is required.
+
+```bash
+# Local gather tree (must contain ai/rapids/cudf/)
+./java/smoke-tests/bin/run.sh --maven-repo-dir /tmp/cudf-java-build/maven-repo
+
+# GitHub Actions gather artifact
+./java/smoke-tests/bin/run.sh \
+  --artifact-url 'https://github.com/rapidsai/cudf/actions/runs/<run>/artifacts/<id>'
+
+# Installed into ~/.m2
+./java/smoke-tests/bin/run.sh --use-maven-home
+
+# Maven Central release (version required)
+./java/smoke-tests/bin/run.sh --use-maven-central --version 25.12.0
+```
+
+Narrow to one CUDA major:
+
+```bash
+./java/smoke-tests/bin/run.sh --maven-repo-dir /tmp/maven-repo --cuda-version 12
+```
+
+## Source modes
+
+| Mode | Flag |
+|---|---|
+| GitHub Actions artifact | `--artifact-url URL` |
+| Local Maven-repo tree | `--maven-repo-dir DIR` |
+| `~/.m2/repository` | `--use-maven-home` |
+| Maven Central | `--use-maven-central` (requires `--version`) |
+
+Shared options:
+
+| Option | Meaning |
+|---|---|
+| `--version VER` | Pin `ai.rapids:cudf` version. Required for Central. For other modes, if omitted, exactly one version directory must exist under `ai/rapids/cudf/`. |
+| `--cuda-version 12\|13` | Narrow classifiers to this CUDA major |
+
+## Classifier selection
+
+Without `--cuda-version`, by host arch:
+
+- `x86_64`: `unclassified`, `cuda12`, `cuda13`
+- `aarch64`: `cuda12-arm64`, `cuda13-arm64`
+
+With `--cuda-version N`:
+
+- `x86_64` + 12: `unclassified`, `cuda12`
+- `x86_64` + 13: `cuda13`
+- `aarch64` + N: `cudaN-arm64`
+
+Missing JARs are warned and skipped. The run fails if no classifier is actually smoke tested, or if any smoke-tested classifier fails.
+
+After each classifier run, `run.sh` also requires the native `CUDF_LOG_WARN` from
+`parquetChunkedLoggerSmoke` (`Chunked Parquet reader: a chunk_read_limit`) in the
+captured smoke log under `.cache/logs/`.
+
+## Artifact downloads
+
+`--artifact-url` uses [`bin/fetch_bundle.sh`](bin/fetch_bundle.sh) (requires authenticated `gh`).
+Downloads land at:
+
+```text
+java/smoke-tests/.cache/downloads/runs/<run_id>/artifacts/<artifact_id>/
+```
+
+(or under `$CUDF_JAVA_SMOKE_OUTPUT_DIR`). If that destination already exists and
+contains `ai/rapids/cudf/`, the fetch warns and reuses it.
+
+## Docker images
+
+`docker/Dockerfile.cuda{12,13}` (Ubuntu 24.04 CUDA runtime + OpenJDK 17 + Maven).
+Built on first use; rebuild with `docker build` / `docker rmi` if the Dockerfile changes.

java/smoke-tests/bin/fetch_bundle.sh

@@ -0,0 +1,111 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Download a java-gather GitHub Actions artifact into:
+#   <output-dir>/runs/<run_id>/artifacts/<artifact_id>/
+# Default <output-dir>: java/smoke-tests/.cache/downloads
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SMOKE_TESTS_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
+
+ARTIFACT_URL=""
+OUTPUT_DIR="${CUDF_JAVA_SMOKE_OUTPUT_DIR:-${SMOKE_TESTS_ROOT}/.cache/downloads}"
+
+info() { printf '==> %s\n' "$*" >&2; }
+warn() { printf 'WARNING: %s\n' "$*" >&2; }
+die()  { printf 'ERROR: %s\n' "$*" >&2; exit 1; }
+
+require_value() {
+  local flag="$1"
+  local value="${2:-}"
+  if [[ -z "${value}" ]]; then
+    die "${flag} requires a value"
+  fi
+}
+
+print_help() {
+  cat << EOF
+Usage: $(basename "$0") --artifact-url <url> [--output-dir DIR]
+
+Download the cudf_java_maven_repo GitHub Actions artifact into:
+  <output-dir>/runs/<run_id>/artifacts/<artifact_id>/
+
+  --output-dir DIR   Default: ${SMOKE_TESTS_ROOT}/.cache/downloads
+                     (or \$CUDF_JAVA_SMOKE_OUTPUT_DIR)
+
+Requires gh. If the destination already exists and looks valid, warns and reuses it.
+EOF
+}
+
+main() {
+  while [[ $# -gt 0 ]]; do
+    case "$1" in
+      -h|--help) print_help; exit 0 ;;
+      --artifact-url)
+        require_value "$1" "${2:-}"
+        ARTIFACT_URL="$2"
+        shift 2
+        ;;
+      --output-dir)
+        require_value "$1" "${2:-}"
+        OUTPUT_DIR="$2"
+        shift 2
+        ;;
+      *) die "Unknown argument: $1 (try --help)" ;;
+    esac
+  done
+
+  if [[ -z "${ARTIFACT_URL}" ]]; then
+    die "--artifact-url is required (try --help)"
+  fi
+  if ! command -v gh >/dev/null 2>&1; then
+    die "'gh' (GitHub CLI) is required"
+  fi
+  if ! command -v unzip >/dev/null 2>&1; then
+    die "'unzip' is required"
+  fi
+
+  local repo run_id artifact_id
+  if [[ "${ARTIFACT_URL}" =~ github\.com/([^/]+/[^/]+)/actions/runs/([A-Za-z0-9_]+)/artifacts/([A-Za-z0-9_]+)/?$ ]]; then
+    repo="${BASH_REMATCH[1]}"
+    run_id="${BASH_REMATCH[2]}"
+    artifact_id="${BASH_REMATCH[3]}"
+  else
+    die "Could not parse artifact URL: ${ARTIFACT_URL}"
+  fi
+
+  local dest="${OUTPUT_DIR}/runs/${run_id}/artifacts/${artifact_id}"
+  if [[ -d "${dest}/ai/rapids/cudf" ]]; then
+    warn "Destination already exists; reusing: ${dest}"
+    printf '%s\n' "${dest}"
+    return 0
+  fi
+  if [[ -e "${dest}" ]]; then
+    die "Destination exists but is incomplete (no ai/rapids/cudf/): ${dest}"
+  fi
+
+  mkdir -p "${dest}"
+  info "Downloading artifact ${artifact_id} from ${repo} run ${run_id}"
+  gh api \
+    -H "Accept: application/vnd.github+json" \
+    "/repos/${repo}/actions/artifacts/${artifact_id}/zip" \
+    > "${dest}/artifact.zip"
+  unzip -q -o "${dest}/artifact.zip" -d "${dest}"
+
+  if [[ -d "${dest}/cudf_java_maven_repo/ai" ]]; then
+    mv "${dest}/cudf_java_maven_repo/ai" "${dest}/"
+    rm -rf "${dest:?}/cudf_java_maven_repo"
+  fi
+  if [[ ! -d "${dest}/ai/rapids/cudf" ]]; then
+    die "No ai/rapids/cudf/ under ${dest} after download"
+  fi
+
+  printf 'artifact-url:%s\n' "${ARTIFACT_URL}" > "${dest}/.source"
+  info "Destination: ${dest}"
+  printf '%s\n' "${dest}"
+}
+
+main "$@"