Vidu Q3 Reference to Video Mix

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "vidu/q3/reference-to-video/mix",
  "audio": true,
  "prompt": "A character walking through a beach catching an apple.",
  "duration": 5,
  "resolution": "720p",
  "aspect_ratio": "16:9",
  "reference_image_urls": [
    "https://static.sandbase.ai/examples/shengshu/vidu/q3/reference-to-video/mix/input_reference_image_urls_0.png",
    "https://static.sandbase.ai/examples/shengshu/vidu/q3/reference-to-video/mix/input_reference_image_urls_1.png",
    "https://static.sandbase.ai/examples/shengshu/vidu/q3/reference-to-video/mix/input_reference_image_urls_2.png"
  ]
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"