diff --git a/api/core/tools/workflow_as_tool/tool.py b/api/core/tools/workflow_as_tool/tool.py
index 1751b45d9b..30334f5da8 100644
--- a/api/core/tools/workflow_as_tool/tool.py
+++ b/api/core/tools/workflow_as_tool/tool.py
@@ -203,7 +203,7 @@ class WorkflowTool(Tool):
         Resolve user object in both HTTP and worker contexts.
 
         In HTTP context: dereference the current_user LocalProxy (can return Account or EndUser).
-        In worker context: load Account from database by user_id (only returns Account, never EndUser).
+        In worker context: load Account(knowledge pipeline) or EndUser(trigger) from database by user_id.
 
         Returns:
             Account | EndUser | None: The resolved user object, or None if resolution fails.
@@ -224,24 +224,28 @@ class WorkflowTool(Tool):
             logger.warning("Failed to resolve user from request context: %s", e)
             return None
 
-    def _resolve_user_from_database(self, user_id: str) -> Account | None:
+    def _resolve_user_from_database(self, user_id: str) -> Account | EndUser | None:
         """
         Resolve user from database (worker/Celery context).
         """
 
-        user_stmt = select(Account).where(Account.id == user_id)
-        user = db.session.scalar(user_stmt)
-        if not user:
-            return None
-
         tenant_stmt = select(Tenant).where(Tenant.id == self.runtime.tenant_id)
         tenant = db.session.scalar(tenant_stmt)
         if not tenant:
             return None
 
-        user.current_tenant = tenant
+        user_stmt = select(Account).where(Account.id == user_id)
+        user = db.session.scalar(user_stmt)
+        if user:
+            user.current_tenant = tenant
+            return user
 
-        return user
+        end_user_stmt = select(EndUser).where(EndUser.id == user_id, EndUser.tenant_id == tenant.id)
+        end_user = db.session.scalar(end_user_stmt)
+        if end_user:
+            return end_user
+
+        return None
 
     def _get_workflow(self, app_id: str, version: str) -> Workflow:
         """
diff --git a/api/tests/unit_tests/core/tools/workflow_as_tool/test_tool.py b/api/tests/unit_tests/core/tools/workflow_as_tool/test_tool.py
index 02bf8e82f1..5d180c7cbc 100644
--- a/api/tests/unit_tests/core/tools/workflow_as_tool/test_tool.py
+++ b/api/tests/unit_tests/core/tools/workflow_as_tool/test_tool.py
@@ -1,3 +1,5 @@
+from types import SimpleNamespace
+
 import pytest
 
 from core.app.entities.app_invoke_entities import InvokeFrom
@@ -214,3 +216,76 @@ def test_create_variable_message():
         assert message.message.variable_name == var_name
         assert message.message.variable_value == var_value
         assert message.message.stream is False
+
+
+def test_resolve_user_from_database_falls_back_to_end_user(monkeypatch: pytest.MonkeyPatch):
+    """Ensure worker context can resolve EndUser when Account is missing."""
+
+    class StubSession:
+        def __init__(self, results: list):
+            self.results = results
+
+        def scalar(self, _stmt):
+            return self.results.pop(0)
+
+    tenant = SimpleNamespace(id="tenant_id")
+    end_user = SimpleNamespace(id="end_user_id", tenant_id="tenant_id")
+    db_stub = SimpleNamespace(session=StubSession([tenant, None, end_user]))
+
+    monkeypatch.setattr("core.tools.workflow_as_tool.tool.db", db_stub)
+
+    entity = ToolEntity(
+        identity=ToolIdentity(author="test", name="test tool", label=I18nObject(en_US="test tool"), provider="test"),
+        parameters=[],
+        description=None,
+        has_runtime_parameters=False,
+    )
+    runtime = ToolRuntime(tenant_id="tenant_id", invoke_from=InvokeFrom.SERVICE_API)
+    tool = WorkflowTool(
+        workflow_app_id="",
+        workflow_as_tool_id="",
+        version="1",
+        workflow_entities={},
+        workflow_call_depth=1,
+        entity=entity,
+        runtime=runtime,
+    )
+
+    resolved_user = tool._resolve_user_from_database(user_id=end_user.id)
+
+    assert resolved_user is end_user
+
+
+def test_resolve_user_from_database_returns_none_when_no_tenant(monkeypatch: pytest.MonkeyPatch):
+    """Return None if tenant cannot be found in worker context."""
+
+    class StubSession:
+        def __init__(self, results: list):
+            self.results = results
+
+        def scalar(self, _stmt):
+            return self.results.pop(0)
+
+    db_stub = SimpleNamespace(session=StubSession([None]))
+    monkeypatch.setattr("core.tools.workflow_as_tool.tool.db", db_stub)
+
+    entity = ToolEntity(
+        identity=ToolIdentity(author="test", name="test tool", label=I18nObject(en_US="test tool"), provider="test"),
+        parameters=[],
+        description=None,
+        has_runtime_parameters=False,
+    )
+    runtime = ToolRuntime(tenant_id="missing_tenant", invoke_from=InvokeFrom.SERVICE_API)
+    tool = WorkflowTool(
+        workflow_app_id="",
+        workflow_as_tool_id="",
+        version="1",
+        workflow_entities={},
+        workflow_call_depth=1,
+        entity=entity,
+        runtime=runtime,
+    )
+
+    resolved_user = tool._resolve_user_from_database(user_id="any")
+
+    assert resolved_user is None