fix(cli): read Workflow.graph when drawing the dev UI graph

src/google/adk/cli/agent_graph.py

@@ -203,12 +203,12 @@ async def build_cluster(
         await build_graph(child, sub_agent, highlight_pairs)
         if parent_agent:
           draw_edge(parent_agent.name, sub_agent.name)
-    elif isinstance(agent, Workflow) and agent._graph is not None:
-      for wf_node in agent._graph.nodes:
+    elif isinstance(agent, Workflow) and agent.graph is not None:
+      for wf_node in agent.graph.nodes:
         if wf_node.name == START.name:
           continue
         await build_graph(child, wf_node, highlight_pairs)
-      for edge in agent._graph.edges:
+      for edge in agent.graph.edges:
         if edge.from_node.name == START.name:
           continue
         label = str(edge.route) if edge.route is not None else ''

tests/unittests/cli/test_agent_graph.py

@@ -23,7 +23,10 @@
 from google.adk.agents.parallel_agent import ParallelAgent
 from google.adk.agents.sequential_agent import SequentialAgent
 from google.adk.cli.agent_graph import get_agent_graph
+from google.adk.events.event import Event
 from google.adk.tools.agent_tool import AgentTool
+from google.adk.workflow import DEFAULT_ROUTE
+from google.adk.workflow import Workflow
 import pytest
 
 _DARK_GREEN = '#0F5223'
@@ -190,6 +193,36 @@ async def test_build_graph_parallel_agent_fans_out_from_the_parent():
   assert 'subgraph "cluster_fanout (Parallel Agent)"' in graph.source
 
 
+@pytest.mark.asyncio
+async def test_build_graph_workflow_draws_nodes_and_edges_from_its_graph():
+  def check(node_input: str):
+    return Event(route='retry')
+
+  def done(node_input: str):
+    return node_input
+
+  writer = LlmAgent(name='writer', model='gemini-2.0-flash')
+  workflow = Workflow(
+      name='flow',
+      edges=[
+          ('START', writer, check),
+          (check, {'retry': writer, DEFAULT_ROUTE: done}),
+      ],
+  )
+
+  graph = await get_agent_graph(workflow, [])
+
+  nodes, edges = _parse(graph.source)
+  # START is never drawn, and back-edges (the retry loop) are kept.
+  assert set(nodes) == {'writer', 'check', 'done'}
+  assert set(edges) == {
+      ('writer', 'check'),
+      ('check', 'writer'),
+      ('check', 'done'),
+  }
+  assert 'subgraph cluster_flow' in graph.source
+
+
 @pytest.mark.asyncio
 async def test_build_graph_highlight_pair_fills_both_nodes_and_colors_edge():
   graph = await get_agent_graph(