[BREAKING] Python: Move single-config fluent methods to constructor parameters (#3693)

* Move single-config fluent methods to constructor parameters

* Updates

* Adjust magentic and group chat

python/packages/devui/README.md

@@ -96,7 +96,7 @@ agents/
 │   ├── agent.py
 │   └── .env             # Optional: API keys, config vars
 ├── my_workflow/
-│   ├── __init__.py      # Must export: workflow = WorkflowBuilder()...
+│   ├── __init__.py      # Must export: workflow = WorkflowBuilder(start_executor=...)...
 │   ├── workflow.py
 │   └── .env             # Optional: environment variables
 └── .env                 # Optional: shared environment variables

python/packages/devui/agent_framework_devui/_discovery.py

@@ -540,7 +540,7 @@ class EntityDiscovery:
 
         This safely checks for module-level assignments like:
         - agent = ChatAgent(...)
-        - workflow = WorkflowBuilder()...
+        - workflow = WorkflowBuilder(start_executor=...)...
 
         Args:
             file_path: Python file to check

python/packages/devui/agent_framework_devui/_executor.py

@@ -441,7 +441,7 @@ class AgentFrameworkExecutor:
                 if not checkpoint_id:
                     error_msg = (
                         "Cannot process HIL responses without a checkpoint. "
-                        "Workflows using HIL must be configured with .with_checkpointing() "
+                        "Workflows using HIL must be configured with checkpoint_storage in constructor"
                         "and a checkpoint must exist before sending responses."
                     )
                     logger.error(error_msg)

python/packages/devui/tests/devui/conftest.py

@@ -488,7 +488,7 @@ async def sequential_workflow() -> tuple[AgentFrameworkExecutor, str, MockBaseCh
         system_message="You are a reviewer. Provide constructive feedback.",
     )
 
-    workflow = SequentialBuilder().participants([writer, reviewer]).build()
+    workflow = SequentialBuilder(participants=[writer, reviewer]).build()
 
     discovery = EntityDiscovery(None)
     mapper = MessageMapper()
@@ -540,7 +540,7 @@ async def concurrent_workflow() -> tuple[AgentFrameworkExecutor, str, MockBaseCh
         system_message="You are a summarizer. Provide concise summaries.",
     )
 
-    workflow = ConcurrentBuilder().participants([researcher, analyst, summarizer]).build()
+    workflow = ConcurrentBuilder(participants=[researcher, analyst, summarizer]).build()
 
     discovery = EntityDiscovery(None)
     mapper = MessageMapper()

python/packages/devui/tests/devui/test_checkpoints.py

@@ -76,12 +76,12 @@ def test_workflow():
     executor = WorkflowTestExecutor(id="test_executor")
     checkpoint_storage = InMemoryCheckpointStorage()
 
-    return (
-        WorkflowBuilder(name="Test Workflow", description="Test checkpoint behavior")
-        .set_start_executor(executor)
-        .with_checkpointing(checkpoint_storage)
-        .build()
-    )
+    return WorkflowBuilder(
+        name="Test Workflow",
+        description="Test checkpoint behavior",
+        start_executor=executor,
+        checkpoint_storage=checkpoint_storage,
+    ).build()
 
 
 class TestCheckpointConversationManager:
@@ -335,7 +335,7 @@ class TestIntegration:
         # Get checkpoint storage for this session
         checkpoint_storage = checkpoint_manager.get_checkpoint_storage(conversation_id)
 
-        # Set build-time storage (equivalent to .with_checkpointing() at build time)
+        # Set build-time storage (equivalent to checkpoint_storage= at build time)
         # Note: In production, DevUI uses runtime injection via run(stream=True) parameter
         if hasattr(test_workflow, "_runner") and hasattr(test_workflow._runner, "context"):
             test_workflow._runner.context._checkpoint_storage = checkpoint_storage
@@ -399,7 +399,7 @@ class TestIntegration:
         """Test that workflows automatically save checkpoints to our conversation-backed storage.
 
         This is the critical end-to-end test that verifies the entire checkpoint flow:
-        1. Storage is set as build-time storage (simulates .with_checkpointing())
+        1. Storage is set as build-time storage (simulates checkpoint_storage=...)
         2. Workflow runs and pauses at HIL point (IDLE_WITH_PENDING_REQUESTS status)
         3. Framework automatically saves checkpoint to our storage
         4. Checkpoint is accessible via manager for UI to list/resume

python/packages/devui/tests/devui/test_discovery.py

@@ -135,10 +135,8 @@ from agent_framework import WorkflowBuilder, FunctionExecutor
 def test_func(input: str) -> str:
     return f"Processed: {input}"
 
-builder = WorkflowBuilder()
 executor = FunctionExecutor(id="test_executor", func=test_func)
-builder.set_start_executor(executor)
-workflow = builder.build()
+workflow = WorkflowBuilder(start_executor=executor).build()
 """)
 
         discovery = EntityDiscovery(str(temp_path))
@@ -182,10 +180,8 @@ from agent_framework import WorkflowBuilder, FunctionExecutor
 def test_func(input: str) -> str:
     return f"Processed: {input}"
 
-builder = WorkflowBuilder()
 executor = FunctionExecutor(id="test_executor", func=test_func)
-builder.set_start_executor(executor)
-workflow = builder.build()
+workflow = WorkflowBuilder(start_executor=executor).build()
 """)
 
         # Create agent with agent.py
@@ -243,10 +239,8 @@ from agent_framework import WorkflowBuilder, FunctionExecutor
 def test_func(input: str) -> str:
     return "v1"
 
-builder = WorkflowBuilder()
 executor = FunctionExecutor(id="test_executor", func=test_func)
-builder.set_start_executor(executor)
-workflow = builder.build()
+workflow = WorkflowBuilder(start_executor=executor).build()
 """)
 
         discovery = EntityDiscovery(str(temp_path))
@@ -266,12 +260,9 @@ def test_func(input: str) -> str:
 def test_func2(input: str) -> str:
     return "v2_extra"
 
-builder = WorkflowBuilder()
 executor1 = FunctionExecutor(id="test_executor", func=test_func)
 executor2 = FunctionExecutor(id="test_executor2", func=test_func2)
-builder.set_start_executor(executor1)
-builder.add_edge(executor1, executor2)
-workflow = builder.build()
+workflow = WorkflowBuilder(start_executor=executor1).add_edge(executor1, executor2).build()
 """)
 
         # Without invalidation, gets cached version
@@ -298,10 +289,8 @@ async def test_in_memory_entities_bypass_lazy_loading():
     def test_func(input: str) -> str:
         return f"Processed: {input}"
 
-    builder = WorkflowBuilder()
     executor = FunctionExecutor(id="test_executor", func=test_func)
-    builder.set_start_executor(executor)
-    workflow = builder.build()
+    workflow = WorkflowBuilder(start_executor=executor).build()
 
     discovery = EntityDiscovery()
 

python/packages/devui/tests/devui/test_execution.py

@@ -175,10 +175,12 @@ async def test_workflow_streaming_execution():
     def process_input(input_data: str) -> str:
         return f"Processed: {input_data}"
 
-    builder = WorkflowBuilder(name="Test Workflow", description="Test workflow for execution")
     start_executor = FunctionExecutor(id="process", func=process_input)
-    builder.set_start_executor(start_executor)
-    workflow = builder.build()
+    workflow = WorkflowBuilder(
+        name="Test Workflow",
+        description="Test workflow for execution",
+        start_executor=start_executor,
+    ).build()
 
     # Create executor and register workflow
     discovery = EntityDiscovery(None)
@@ -213,10 +215,12 @@ async def test_workflow_sync_execution():
     def echo(text: str) -> str:
         return f"Echo: {text}"
 
-    builder = WorkflowBuilder(name="Echo Workflow", description="Simple echo workflow")
     start_executor = FunctionExecutor(id="echo", func=echo)
-    builder.set_start_executor(start_executor)
-    workflow = builder.build()
+    workflow = WorkflowBuilder(
+        name="Echo Workflow",
+        description="Simple echo workflow",
+        start_executor=start_executor,
+    ).build()
 
     # Create executor and register workflow
     discovery = EntityDiscovery(None)
@@ -308,10 +312,12 @@ async def test_full_pipeline_workflow_events_are_json_serializable():
         system_message="You are a test assistant.",
     )
 
-    builder = WorkflowBuilder(name="Serialization Test Workflow", description="Test workflow")
     agent_executor = AgentExecutor(id="agent_node", agent=agent)
-    builder.set_start_executor(agent_executor)
-    workflow = builder.build()
+    workflow = WorkflowBuilder(
+        name="Serialization Test Workflow",
+        description="Test workflow",
+        start_executor=agent_executor,
+    ).build()
 
     # Create executor and register
     discovery = EntityDiscovery(None)
@@ -420,11 +426,11 @@ async def test_executor_parse_structured_extracts_input_for_string_workflow():
         async def process(self, text: str, ctx: WorkflowContext[Any, Any]) -> None:
             await ctx.yield_output(f"Got: {text}")
 
-    workflow = (
-        WorkflowBuilder(name="String Workflow", description="Accepts string")
-        .set_start_executor(StringInputExecutor(id="str_exec"))
-        .build()
-    )
+    workflow = WorkflowBuilder(
+        name="String Workflow",
+        description="Accepts string",
+        start_executor=StringInputExecutor(id="str_exec"),
+    ).build()
 
     executor = AgentFrameworkExecutor(EntityDiscovery(None), MessageMapper())
 
@@ -445,11 +451,11 @@ async def test_executor_parse_raw_string_for_string_workflow():
         async def process(self, text: str, ctx: WorkflowContext[Any, Any]) -> None:
             await ctx.yield_output(f"Got: {text}")
 
-    workflow = (
-        WorkflowBuilder(name="String Workflow", description="Accepts string")
-        .set_start_executor(StringInputExecutor(id="str_exec"))
-        .build()
-    )
+    workflow = WorkflowBuilder(
+        name="String Workflow",
+        description="Accepts string",
+        start_executor=StringInputExecutor(id="str_exec"),
+    ).build()
 
     executor = AgentFrameworkExecutor(EntityDiscovery(None), MessageMapper())
 
@@ -490,11 +496,11 @@ async def test_executor_parse_stringified_json_workflow_input():
             await ctx.yield_output(f"Got: {data.input}")
 
     # Build workflow with Pydantic input type
-    workflow = (
-        WorkflowBuilder(name="Pydantic Workflow", description="Accepts Pydantic input")
-        .set_start_executor(PydanticInputExecutor(id="pydantic_exec"))
-        .build()
-    )
+    workflow = WorkflowBuilder(
+        name="Pydantic Workflow",
+        description="Accepts Pydantic input",
+        start_executor=PydanticInputExecutor(id="pydantic_exec"),
+    ).build()
 
     executor = AgentFrameworkExecutor(EntityDiscovery(None), MessageMapper())
 
@@ -689,11 +695,11 @@ async def test_full_pipeline_workflow_output_event_serialization():
             await ctx.yield_output({"final": "result", "data": [1, 2, 3]})
 
     # Build workflow
-    workflow = (
-        WorkflowBuilder(name="Output Workflow", description="Tests yield_output")
-        .set_start_executor(OutputtingExecutor(id="outputter"))
-        .build()
-    )
+    workflow = WorkflowBuilder(
+        name="Output Workflow",
+        description="Tests yield_output",
+        start_executor=OutputtingExecutor(id="outputter"),
+    ).build()
 
     # Create DevUI executor and register workflow
     discovery = EntityDiscovery(None)