fix(auth): share internal gateway token across workers (#3184)

* fix(auth): share internal gateway token across workers

* fix: restore deploy script executable bit

* Update deploy.sh

to skip the auth_token setup for the down command

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/tests/test_internal_auth.py

@@ -0,0 +1,35 @@
+"""Tests for Gateway internal auth token handling."""
+
+from __future__ import annotations
+
+import importlib
+
+
+def test_internal_auth_uses_shared_env_token(monkeypatch):
+    import app.gateway.internal_auth as internal_auth
+
+    monkeypatch.setenv("DEER_FLOW_INTERNAL_AUTH_TOKEN", "shared-token")
+    reloaded = importlib.reload(internal_auth)
+    try:
+        headers = reloaded.create_internal_auth_headers()
+
+        assert headers[reloaded.INTERNAL_AUTH_HEADER_NAME] == "shared-token"
+        assert reloaded.is_valid_internal_auth_token("shared-token") is True
+        assert reloaded.is_valid_internal_auth_token("other-token") is False
+    finally:
+        monkeypatch.delenv("DEER_FLOW_INTERNAL_AUTH_TOKEN", raising=False)
+        importlib.reload(reloaded)
+
+
+def test_internal_auth_generates_process_local_fallback(monkeypatch):
+    import app.gateway.internal_auth as internal_auth
+
+    monkeypatch.delenv("DEER_FLOW_INTERNAL_AUTH_TOKEN", raising=False)
+    reloaded = importlib.reload(internal_auth)
+    try:
+        token = reloaded.create_internal_auth_headers()[reloaded.INTERNAL_AUTH_HEADER_NAME]
+
+        assert token
+        assert reloaded.is_valid_internal_auth_token(token) is True
+    finally:
+        importlib.reload(reloaded)