diff --git a/docker-compose.yml b/docker-compose.yml
index 7ab466f..f666a92 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -46,3 +46,40 @@ services:
       retries: 3
       start_period: 120s
     restart: unless-stopped
+
+  trainer:
+    profiles: [train]
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        CUDA_TAG: ${CUDA_TAG:-cu128}
+    init: true
+    user: "${UID:-1000}:${GID:-1000}"
+    volumes:
+      - ${TRAIN_DATA_DIR:-./data}:/data:ro
+      - ${TRAIN_MODEL_DIR:-./params}:/models/base:ro
+      - ${TRAIN_CHECKPOINT_DIR:-./checkpoints}:/checkpoints
+    environment:
+      - TRAIN_JOB_NAME=${TRAIN_JOB_NAME:-astrai-train}
+      - TRAIN_CONFIG=${TRAIN_CONFIG:-}
+      - BASE_MODEL=${BASE_MODEL:-/models/base}
+      - CHECKPOINT_ROOT=/checkpoints
+      - TRAIN_GPU_COUNT=${TRAIN_GPU_COUNT:-all}
+      - CUDA_VISIBLE_DEVICES
+    entrypoint: ["bash", "/app/scripts/docker/train-entrypoint.sh"]
+    ipc: ${TRAIN_IPC_MODE:-host}
+    stop_grace_period: ${TRAIN_STOP_GRACE_PERIOD:-10m}
+    restart: "no"
+    logging:
+      driver: json-file
+      options:
+        max-size: ${TRAIN_LOG_MAX_SIZE:-100m}
+        max-file: ${TRAIN_LOG_MAX_FILES:-5}
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: ${TRAIN_GPU_COUNT:-all}
+              capabilities: [gpu]
diff --git a/scripts/docker/lib/train-common.sh b/scripts/docker/lib/train-common.sh
new file mode 100755
index 0000000..8d6f56a
--- /dev/null
+++ b/scripts/docker/lib/train-common.sh
@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+
+log_info() {
+    printf '[INFO] %s\n' "$*"
+}
+
+log_warn() {
+    printf '[WARN] %s\n' "$*" >&2
+}
+
+die() {
+    printf '[ERROR] %s\n' "$*" >&2
+    exit 1
+}
+
+require_command() {
+    command -v "$1" >/dev/null 2>&1 || die "Required command not found: $1"
+}
+
+validate_job_name() {
+    [[ "$1" =~ ^[A-Za-z0-9][A-Za-z0-9._-]*$ ]] ||
+        die "Invalid TRAIN_JOB_NAME '$1'; use letters, numbers, dot, underscore, or dash"
+}
+
+checkpoint_is_complete() {
+    local checkpoint="$1"
+    local file
+
+    [[ -d "${checkpoint}" ]] || return 1
+
+    for file in meta.json config.json model.safetensors optimizer.pt scheduler.pt; do
+        [[ -s "${checkpoint}/${file}" ]] || return 1
+    done
+
+    return 0
+}
+
+checkpoint_coordinates() {
+    local name
+
+    name="$(basename "$1")"
+    [[ "${name}" =~ ^epoch_([0-9]+)_step_([0-9]+)$ ]] || return 1
+    printf '%d %d\n' "$((10#${BASH_REMATCH[1]}))" "$((10#${BASH_REMATCH[2]}))"
+}
+
+list_complete_checkpoints() {
+    local checkpoint_dir="$1"
+    local checkpoint coordinates epoch step
+
+    for checkpoint in "${checkpoint_dir}"/epoch_*_step_*; do
+        [[ -d "${checkpoint}" ]] || continue
+        coordinates="$(checkpoint_coordinates "${checkpoint}")" || continue
+        checkpoint_is_complete "${checkpoint}" || continue
+        read -r epoch step <<<"${coordinates}"
+        printf '%012d %012d %s\n' "${epoch}" "${step}" "${checkpoint}"
+    done | sort -n -k1,1 -k2,2
+}
+
+find_latest_checkpoint() {
+    local checkpoint_dir="$1"
+    local latest
+
+    latest="$(list_complete_checkpoints "${checkpoint_dir}" | tail -n 1)"
+    [[ -n "${latest}" ]] || return 1
+    printf '%s\n' "${latest#* * }"
+}
diff --git a/scripts/docker/train-entrypoint.sh b/scripts/docker/train-entrypoint.sh
new file mode 100755
index 0000000..af590d0
--- /dev/null
+++ b/scripts/docker/train-entrypoint.sh
@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+source "${SCRIPT_DIR}/lib/train-common.sh"
+
+TRAIN_JOB_NAME="${TRAIN_JOB_NAME:?TRAIN_JOB_NAME is required}"
+CHECKPOINT_ROOT="${CHECKPOINT_ROOT:-/checkpoints}"
+CHECKPOINT_DIR="${CHECKPOINT_ROOT}/${TRAIN_JOB_NAME}"
+BASE_MODEL="${BASE_MODEL:-/models/base}"
+TRAIN_CONFIG="${TRAIN_CONFIG:-}"
+TRAIN_GPU_COUNT="${TRAIN_GPU_COUNT:-all}"
+
+validate_job_name "${TRAIN_JOB_NAME}"
+if [[ "${TRAIN_GPU_COUNT}" == "all" ]]; then
+    TRAIN_GPU_COUNT="$(python -c 'import torch; print(torch.cuda.device_count())')"
+fi
+[[ "${TRAIN_GPU_COUNT}" =~ ^[1-9][0-9]*$ ]] || die "No visible GPU found"
+if [[ -n "${TRAIN_CONFIG}" ]]; then
+    [[ -f "${TRAIN_CONFIG}" ]] || die "Training config not found: ${TRAIN_CONFIG}"
+fi
+[[ -r /data ]] || die "Training data directory is not readable: /data"
+
+mkdir -p "${CHECKPOINT_DIR}"
+[[ -w "${CHECKPOINT_DIR}" ]] || die "Checkpoint directory is not writable: ${CHECKPOINT_DIR}"
+
+latest_checkpoint="$(find_latest_checkpoint "${CHECKPOINT_DIR}" || true)"
+
+train_args=(
+    python scripts/tools/train.py
+    --ckpt_dir "${CHECKPOINT_DIR}"
+    --nprocs "${TRAIN_GPU_COUNT}"
+)
+
+if [[ -n "${TRAIN_CONFIG}" ]]; then
+    train_args+=(--config "${TRAIN_CONFIG}")
+fi
+
+if (( TRAIN_GPU_COUNT > 1 )); then
+    train_args+=(--parallel_mode ddp)
+else
+    train_args+=(--parallel_mode none)
+fi
+
+if [[ -n "${latest_checkpoint}" ]]; then
+    log_info "Resuming ${TRAIN_JOB_NAME} from ${latest_checkpoint}"
+    train_args+=(--param_path "${latest_checkpoint}" --resume)
+else
+    [[ -s "${BASE_MODEL}/config.json" ]] || die "Base model config not found: ${BASE_MODEL}/config.json"
+    [[ -s "${BASE_MODEL}/model.safetensors" ]] || die "Base model weights not found: ${BASE_MODEL}/model.safetensors"
+    log_info "Starting ${TRAIN_JOB_NAME} from ${BASE_MODEL}"
+    train_args+=(--param_path "${BASE_MODEL}")
+fi
+
+log_info "GPUs=${TRAIN_GPU_COUNT}, checkpoints=${CHECKPOINT_DIR}"
+
+# Replace the shell so the container init forwards SIGTERM to the trainer.
+exec "${train_args[@]}" "$@"
diff --git a/scripts/train.sh b/scripts/train.sh
new file mode 100755
index 0000000..0f2bd9d
--- /dev/null
+++ b/scripts/train.sh
@@ -0,0 +1,323 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
+source "${ROOT_DIR}/scripts/docker/lib/train-common.sh"
+
+ENV_FILE="${TRAIN_ENV_FILE:-${ROOT_DIR}/.env.train}"
+COMPOSE_BASE=(
+    docker compose
+    --project-directory "${ROOT_DIR}"
+    --file "${ROOT_DIR}/docker-compose.yml"
+    --profile train
+)
+
+usage() {
+    cat <<'EOF'
+Usage: scripts/train.sh <command> [options]
+
+Commands:
+  init                 Create local directories and .env.train
+  preflight            Validate Docker, paths, GPU settings, and Compose
+  build                Build the trainer image
+  start [--foreground] [-- ARGS...] Start or resume training
+  stop                 Gracefully stop and checkpoint training
+  restart              Stop, then start training
+  logs                 Follow trainer logs
+  status               Show container and latest checkpoint status
+  latest               Print the latest complete checkpoint path
+  list                 List all complete checkpoints
+  clean [--keep N]     Preview old checkpoint removal
+  clean --force        Remove old checkpoints after previewing
+
+Environment:
+  TRAIN_ENV_FILE       Env file path (default: .env.train)
+  TRAIN_CONFIG_FILE    Optional host YAML mounted only when the job starts
+
+Training arguments come from an externally mounted TRAIN_CONFIG or ARGS passed
+after --. The image does not contain experiment configuration.
+EOF
+}
+
+load_env() {
+    if [[ -f "${ENV_FILE}" ]]; then
+        set -a
+        # shellcheck disable=SC1090
+        source "${ENV_FILE}"
+        set +a
+    fi
+
+    TRAIN_JOB_NAME="${TRAIN_JOB_NAME:-astrai-train}"
+    TRAIN_DATA_DIR="${TRAIN_DATA_DIR:-./data}"
+    TRAIN_MODEL_DIR="${TRAIN_MODEL_DIR:-./params}"
+    TRAIN_CHECKPOINT_DIR="${TRAIN_CHECKPOINT_DIR:-./checkpoints}"
+    TRAIN_GPU_COUNT="${TRAIN_GPU_COUNT:-all}"
+    TRAIN_STOP_TIMEOUT="${TRAIN_STOP_TIMEOUT:-600}"
+
+    validate_job_name "${TRAIN_JOB_NAME}"
+}
+
+resolve_path() {
+    if [[ "$1" = /* ]]; then
+        printf '%s\n' "$1"
+    else
+        printf '%s/%s\n' "${ROOT_DIR}" "${1#./}"
+    fi
+}
+
+checkpoint_dir() {
+    printf '%s/%s\n' "$(resolve_path "${TRAIN_CHECKPOINT_DIR}")" "${TRAIN_JOB_NAME}"
+}
+
+compose() {
+    local -a command=("${COMPOSE_BASE[@]}")
+
+    if [[ -f "${ENV_FILE}" ]]; then
+        command+=(--env-file "${ENV_FILE}")
+    fi
+    "${command[@]}" "$@"
+}
+
+init_environment() {
+    local data_dir model_dir checkpoints_dir
+
+    data_dir="$(resolve_path "${TRAIN_DATA_DIR}")"
+    model_dir="$(resolve_path "${TRAIN_MODEL_DIR}")"
+    checkpoints_dir="$(resolve_path "${TRAIN_CHECKPOINT_DIR}")"
+    mkdir -p "${data_dir}" "${model_dir}" "${checkpoints_dir}"
+
+    if [[ ! -f "${ENV_FILE}" ]]; then
+        cat >"${ENV_FILE}" <<'EOF'
+TRAIN_JOB_NAME=astrai-train
+TRAIN_DATA_DIR=./data
+TRAIN_MODEL_DIR=./params
+TRAIN_CHECKPOINT_DIR=./checkpoints
+TRAIN_CONFIG_FILE=
+TRAIN_GPU_COUNT=all
+# CUDA_VISIBLE_DEVICES=0,1
+CUDA_TAG=cu128
+TRAIN_IPC_MODE=host
+TRAIN_STOP_GRACE_PERIOD=10m
+TRAIN_STOP_TIMEOUT=600
+CHECKPOINT_KEEP_LAST=5
+EOF
+        log_info "Created ${ENV_FILE}"
+    else
+        log_info "Keeping existing ${ENV_FILE}"
+    fi
+    log_info "Data: ${data_dir}"
+    log_info "Model: ${model_dir}"
+    log_info "Checkpoints: ${checkpoints_dir}"
+}
+
+preflight() {
+    local data_dir model_dir checkpoints_dir config_file latest visible_count
+
+    require_command docker
+    docker info >/dev/null 2>&1 || die "Docker daemon is unavailable"
+    [[ "${TRAIN_GPU_COUNT}" == "all" || "${TRAIN_GPU_COUNT}" =~ ^[1-9][0-9]*$ ]] ||
+        die "TRAIN_GPU_COUNT must be 'all' or a positive integer"
+
+    data_dir="$(resolve_path "${TRAIN_DATA_DIR}")"
+    model_dir="$(resolve_path "${TRAIN_MODEL_DIR}")"
+    checkpoints_dir="$(resolve_path "${TRAIN_CHECKPOINT_DIR}")"
+    [[ -d "${data_dir}" ]] || die "Training data directory not found: ${data_dir}"
+    mkdir -p "${checkpoints_dir}/${TRAIN_JOB_NAME}"
+    [[ -w "${checkpoints_dir}/${TRAIN_JOB_NAME}" ]] || die "Checkpoint directory is not writable"
+
+    if [[ -n "${TRAIN_CONFIG_FILE:-}" ]]; then
+        config_file="$(resolve_path "${TRAIN_CONFIG_FILE}")"
+        [[ -f "${config_file}" ]] || die "Training config not found: ${config_file}"
+    fi
+
+    latest="$(find_latest_checkpoint "${checkpoints_dir}/${TRAIN_JOB_NAME}" || true)"
+    if [[ -z "${latest}" ]]; then
+        [[ -s "${model_dir}/config.json" ]] || die "Model config not found: ${model_dir}/config.json"
+        [[ -s "${model_dir}/model.safetensors" ]] || die "Model weights not found: ${model_dir}/model.safetensors"
+    else
+        log_info "Resume candidate: ${latest}"
+    fi
+
+    if [[ -n "${CUDA_VISIBLE_DEVICES:-}" && "${TRAIN_GPU_COUNT}" != "all" ]]; then
+        IFS=',' read -r -a visible_gpus <<<"${CUDA_VISIBLE_DEVICES}"
+        visible_count="${#visible_gpus[@]}"
+        (( visible_count == TRAIN_GPU_COUNT )) ||
+            die "TRAIN_GPU_COUNT=${TRAIN_GPU_COUNT}, but CUDA_VISIBLE_DEVICES exposes ${visible_count} GPU(s)"
+    fi
+
+    compose config --quiet
+    log_info "Preflight passed for ${TRAIN_JOB_NAME} (GPU request: ${TRAIN_GPU_COUNT})"
+}
+
+start_training() {
+    local foreground="$1"
+    local config_file container running
+    local -a run_options=()
+    shift
+
+    preflight
+    if [[ -n "${TRAIN_CONFIG_FILE:-}" ]]; then
+        config_file="$(resolve_path "${TRAIN_CONFIG_FILE}")"
+        run_options+=(
+            --volume "${config_file}:/run/astrai/train.yaml:ro"
+            --env TRAIN_CONFIG=/run/astrai/train.yaml
+        )
+    elif [[ -z "${TRAIN_CONFIG:-}" && $# -eq 0 ]]; then
+        die "Set TRAIN_CONFIG_FILE or pass complete trainer arguments after --"
+    fi
+
+    container="astrai-trainer-${TRAIN_JOB_NAME}"
+    running="$(docker inspect --format '{{.State.Running}}' "${container}" 2>/dev/null || true)"
+    [[ "${running}" != "true" ]] || die "Trainer is already running: ${container}"
+    docker rm "${container}" >/dev/null 2>&1 || true
+    if [[ "${foreground}" == "true" ]]; then
+        compose run --build --rm "${run_options[@]}" trainer "$@"
+    else
+        compose run -d --build --name "${container}" \
+            "${run_options[@]}" trainer "$@"
+        log_info "Training started; run scripts/train.sh logs to follow it"
+    fi
+}
+
+stop_training() {
+    log_info "Stopping trainer with ${TRAIN_STOP_TIMEOUT}s grace period"
+    docker stop --timeout "${TRAIN_STOP_TIMEOUT}" "astrai-trainer-${TRAIN_JOB_NAME}" >/dev/null 2>&1 ||
+        log_warn "Trainer container is not running"
+}
+
+restart_training() {
+    local container="astrai-trainer-${TRAIN_JOB_NAME}"
+
+    docker inspect "${container}" >/dev/null 2>&1 ||
+        die "Trainer container not found; use start with a config or CLI arguments first"
+    log_info "Restarting trainer with ${TRAIN_STOP_TIMEOUT}s grace period"
+    docker restart --timeout "${TRAIN_STOP_TIMEOUT}" "${container}" >/dev/null
+}
+
+show_status() {
+    local latest
+
+    docker ps -a --filter "name=^/astrai-trainer-${TRAIN_JOB_NAME}$"
+    latest="$(find_latest_checkpoint "$(checkpoint_dir)" || true)"
+    if [[ -n "${latest}" ]]; then
+        log_info "Latest checkpoint: ${latest}"
+    else
+        log_info "No complete checkpoint found for ${TRAIN_JOB_NAME}"
+    fi
+}
+
+clean_checkpoints() {
+    local keep="$1" force="$2" dir count remove_count index path
+    local -a checkpoints=()
+
+    [[ "${keep}" =~ ^[1-9][0-9]*$ ]] || die "--keep must be a positive integer"
+    dir="$(checkpoint_dir)"
+    while IFS= read -r line; do
+        [[ -n "${line}" ]] && checkpoints+=("${line#* * }")
+    done < <(list_complete_checkpoints "${dir}")
+
+    count="${#checkpoints[@]}"
+    remove_count=$((count - keep))
+    if (( remove_count <= 0 )); then
+        log_info "Nothing to clean; ${count} complete checkpoint(s), keeping ${keep}"
+        return
+    fi
+
+    for ((index = 0; index < remove_count; index++)); do
+        path="${checkpoints[index]}"
+        if [[ "${force}" == "true" ]]; then
+            rm -rf -- "${path}"
+            log_info "Removed ${path}"
+        else
+            printf 'Would remove %s\n' "${path}"
+        fi
+    done
+    [[ "${force}" == "true" ]] || log_warn "Preview only; add --force to delete"
+}
+
+main() {
+    local command="${1:-}" foreground=false keep="${CHECKPOINT_KEEP_LAST:-5}" force=false
+    local -a train_args=()
+    [[ -n "${command}" ]] || { usage; exit 1; }
+    shift || true
+    load_env
+
+    case "${command}" in
+        init)
+            init_environment
+            ;;
+        preflight)
+            preflight
+            ;;
+        build)
+            preflight
+            compose build trainer
+            ;;
+        start)
+            while [[ $# -gt 0 ]]; do
+                case "$1" in
+                    --foreground)
+                        foreground=true
+                        shift
+                        ;;
+                    --)
+                        shift
+                        train_args=("$@")
+                        break
+                        ;;
+                    *)
+                        die "Unknown start option: $1 (put trainer arguments after --)"
+                        ;;
+                esac
+            done
+            start_training "${foreground}" "${train_args[@]}"
+            ;;
+        stop)
+            stop_training
+            ;;
+        restart)
+            restart_training
+            ;;
+        logs)
+            docker logs -f --tail "${TRAIN_LOG_TAIL:-200}" "astrai-trainer-${TRAIN_JOB_NAME}"
+            ;;
+        status)
+            show_status
+            ;;
+        latest)
+            find_latest_checkpoint "$(checkpoint_dir)" || die "No complete checkpoint found"
+            ;;
+        list)
+            list_complete_checkpoints "$(checkpoint_dir)" | while read -r _epoch _step path; do
+                printf '%s\n' "${path}"
+            done
+            ;;
+        clean)
+            while [[ $# -gt 0 ]]; do
+                case "$1" in
+                    --keep)
+                        [[ $# -ge 2 ]] || die "--keep requires a value"
+                        keep="$2"
+                        shift 2
+                        ;;
+                    --force)
+                        force=true
+                        shift
+                        ;;
+                    *)
+                        die "Unknown clean option: $1"
+                        ;;
+                esac
+            done
+            clean_checkpoints "${keep}" "${force}"
+            ;;
+        help|-h|--help)
+            usage
+            ;;
+        *)
+            die "Unknown command: ${command}"
+            ;;
+    esac
+}
+
+main "$@"