diff --git a/scripts/build_video_split.sh b/scripts/build_video_split.sh
index 56bcfdb..337c476 100755
--- a/scripts/build_video_split.sh
+++ b/scripts/build_video_split.sh
@@ -49,5 +49,11 @@ if [ "${MODE:-}" = "mock" ]; then
   DRY_RUN_FLAG="--dry-run"
 fi
 
+# 诊断并发上限（asyncio.Semaphore）：默认 12，可用 CONCURRENCY 环境变量覆盖。
+# 注：LLM 熔断阈值/冷却是工程配置，走 .env（LLM_CIRCUIT_BREAKER_THRESHOLD / _COOLDOWN），
+#     当前 threshold=32（连续 32 次失败触发熔断），不在本脚本设置。
+CONCURRENCY="${CONCURRENCY:-12}"
+
 conda run -n Video-Tree-TRM python -m app.harness.video_split_cli \
-  --config config/video_split.yaml ${DRY_RUN_FLAG}
+  --config config/video_split.yaml \
+  --concurrency "${CONCURRENCY}" ${DRY_RUN_FLAG}