Increase frame inspection depth to detect parent_flow (#4231)

This commit fixes a bug where `parent_flow` was not being set because
the maximum depth was not sufficient to search for an instance of `Flow`
in the current call stack frame during Flow instantiation.

lib/crewai/src/crewai/flow/flow_trackable.py

@@ -1,4 +1,5 @@
 import inspect
+from typing import Any
 
 from pydantic import BaseModel, Field, InstanceOf, model_validator
 from typing_extensions import Self
@@ -14,14 +15,14 @@ class FlowTrackable(BaseModel):
     inspecting the call stack.
     """
 
-    parent_flow: InstanceOf[Flow] | None = Field(
+    parent_flow: InstanceOf[Flow[Any]] | None = Field(
         default=None,
         description="The parent flow of the instance, if it was created inside a flow.",
     )
 
     @model_validator(mode="after")
     def _set_parent_flow(self) -> Self:
-        max_depth = 5
+        max_depth = 8
         frame = inspect.currentframe()
 
         try:

lib/crewai/tests/test_crew.py

@@ -4500,6 +4500,71 @@ def test_crew_copy_with_memory():
         pytest.fail(f"Copying crew raised an unexpected exception: {e}")
 
 
+def test_sets_parent_flow_when_using_crewbase_pattern_inside_flow():
+    @CrewBase
+    class TestCrew:
+        agents_config = None
+        tasks_config = None
+
+        agents: list[BaseAgent]
+        tasks: list[Task]
+
+        @agent
+        def researcher(self) -> Agent:
+            return Agent(
+                role="Researcher",
+                goal="Research things",
+                backstory="Expert researcher",
+            )
+
+        @agent
+        def writer_agent(self) -> Agent:
+            return Agent(
+                role="Writer",
+                goal="Write things",
+                backstory="Expert writer",
+            )
+
+        @task
+        def research_task(self) -> Task:
+            return Task(
+                description="Test task for researcher",
+                expected_output="output",
+                agent=self.researcher(),
+            )
+
+        @task
+        def write_task(self) -> Task:
+            return Task(
+                description="Test task for writer",
+                expected_output="output",
+                agent=self.writer_agent(),
+            )
+
+        @crew
+        def crew(self) -> Crew:
+            return Crew(
+                agents=self.agents,
+                tasks=self.tasks,
+                process=Process.sequential,
+            )
+
+    captured_crew = None
+
+    class MyFlow(Flow):
+        @start()
+        def start_method(self):
+            nonlocal captured_crew
+            captured_crew = TestCrew().crew()
+            return captured_crew
+
+    flow = MyFlow()
+    flow.kickoff()
+
+    assert captured_crew is not None
+    assert captured_crew.parent_flow is flow
+
+
 def test_sets_parent_flow_when_outside_flow(researcher, writer):
     crew = Crew(
         agents=[researcher, writer],