diff --git a/backend/app/gateway/routers/channel_connections.py b/backend/app/gateway/routers/channel_connections.py
index 0733ff2890..ef25aa4545 100644
--- a/backend/app/gateway/routers/channel_connections.py
+++ b/backend/app/gateway/routers/channel_connections.py
@@ -747,8 +747,9 @@ async def _require_wechat_qr_login(request: Request) -> ChannelConnectionsConfig
     # QR sessions and mutation locks live in one process. Reject every QR route
     # before session access when requests could land on different workers.
     # WEB_CONCURRENCY is Uvicorn's fallback when no worker count is supplied.
+    # A blank value means "unset", as the compose command's ${GATEWAY_WORKERS:-1} treats it.
     try:
-        workers = int(os.environ.get("GATEWAY_WORKERS", os.environ.get("WEB_CONCURRENCY", "1")))
+        workers = int(os.environ.get("GATEWAY_WORKERS") or os.environ.get("WEB_CONCURRENCY") or "1")
     except ValueError:
         workers = 0
     if workers != 1:
diff --git a/backend/packages/harness/deerflow/integrations/lark_broker.py b/backend/packages/harness/deerflow/integrations/lark_broker.py
index 63c2d5a187..35dfa17c76 100644
--- a/backend/packages/harness/deerflow/integrations/lark_broker.py
+++ b/backend/packages/harness/deerflow/integrations/lark_broker.py
@@ -430,8 +430,9 @@ def _config_from_env() -> BrokerConfig:
         config_dir=os.environ.get("LARKSUITE_CLI_CONFIG_DIR", "/var/lark/config"),
         data_dir=os.environ.get("LARKSUITE_CLI_DATA_DIR", "/var/lark/data"),
         host=os.environ.get("DEERFLOW_LARK_BROKER_HOST", LARK_BROKER_DEFAULT_HOST),
-        port=int(os.environ.get("DEERFLOW_LARK_BROKER_PORT", str(LARK_BROKER_DEFAULT_PORT))),
-        timeout_seconds=int(os.environ.get("DEERFLOW_LARK_BROKER_TIMEOUT", str(LARK_BROKER_DEFAULT_TIMEOUT_SECONDS))),
+        # A blank value means "unset" (`-e DEERFLOW_LARK_BROKER_PORT=`); int("") would abort startup.
+        port=int(os.environ.get("DEERFLOW_LARK_BROKER_PORT") or LARK_BROKER_DEFAULT_PORT),
+        timeout_seconds=int(os.environ.get("DEERFLOW_LARK_BROKER_TIMEOUT") or LARK_BROKER_DEFAULT_TIMEOUT_SECONDS),
         deny_subcommands=parse_deny_subcommands(os.environ.get(LARK_BROKER_DENY_SUBCOMMANDS_ENV)),
     )
 
diff --git a/backend/tests/test_channel_connections_router.py b/backend/tests/test_channel_connections_router.py
index 304eab7289..e48f008083 100644
--- a/backend/tests/test_channel_connections_router.py
+++ b/backend/tests/test_channel_connections_router.py
@@ -1226,7 +1226,7 @@ def test_disconnect_connection_is_current_user_scoped(tmp_path):
     anyio.run(repo.close)
 
 
-@pytest.mark.parametrize("worker_env", [{}, {"GATEWAY_WORKERS": "1"}, {"WEB_CONCURRENCY": "1"}])
+@pytest.mark.parametrize("worker_env", [{}, {"GATEWAY_WORKERS": "1"}, {"WEB_CONCURRENCY": "1"}, {"GATEWAY_WORKERS": ""}])
 def test_wechat_qr_login_saves_credentials_without_exposing_token(monkeypatch, worker_env):
     from app.channels.wechat_qr_login import WechatQRLogin
 
@@ -1366,7 +1366,17 @@ def test_wechat_qr_confirmation_preserves_bot_id_unless_replaced(monkeypatch, re
     assert saved == expected
 
 
-@pytest.mark.parametrize("worker_env", [{"GATEWAY_WORKERS": "2"}, {"GATEWAY_WORKERS": "4"}, {"WEB_CONCURRENCY": "2"}, {"GATEWAY_WORKERS": "invalid"}])
+@pytest.mark.parametrize(
+    "worker_env",
+    [
+        {"GATEWAY_WORKERS": "2"},
+        {"GATEWAY_WORKERS": "4"},
+        {"WEB_CONCURRENCY": "2"},
+        {"GATEWAY_WORKERS": "invalid"},
+        # A blank GATEWAY_WORKERS is unset, so WEB_CONCURRENCY still decides.
+        {"GATEWAY_WORKERS": "", "WEB_CONCURRENCY": "2"},
+    ],
+)
 @pytest.mark.parametrize("method,suffix", [("POST", ""), ("POST", "/session/poll"), ("DELETE", "/session")])
 def test_wechat_qr_routes_reject_unsupported_workers_before_session_access(monkeypatch, worker_env, method, suffix):
     from app.channels.wechat_qr_login import WechatQRLogin
diff --git a/backend/tests/test_lark_broker.py b/backend/tests/test_lark_broker.py
index 83e4c54820..77f557b380 100644
--- a/backend/tests/test_lark_broker.py
+++ b/backend/tests/test_lark_broker.py
@@ -355,3 +355,15 @@ def test_allowed_subcommand_still_runs_with_denylist(tmp_path: Path) -> None:
     assert result.exit_code == 0
     payload = json.loads(result.stdout.decode())
     assert payload["argv"] == ["auth", "status"]
+
+
+@pytest.mark.parametrize("name", ["DEERFLOW_LARK_BROKER_PORT", "DEERFLOW_LARK_BROKER_TIMEOUT"])
+def test_config_from_env_treats_blank_numbers_as_unset(monkeypatch, name) -> None:
+    monkeypatch.delenv("DEERFLOW_LARK_BROKER_PORT", raising=False)
+    monkeypatch.delenv("DEERFLOW_LARK_BROKER_TIMEOUT", raising=False)
+    monkeypatch.setenv(name, "")
+
+    config = lark_broker._config_from_env()
+
+    assert config.port == lark_broker.LARK_BROKER_DEFAULT_PORT
+    assert config.timeout_seconds == lark_broker.LARK_BROKER_DEFAULT_TIMEOUT_SECONDS