Subgraph Events Not Captured in Main Graph Stream

[YassinNouh21]

## Issue
Main graph stream not capturing events from executor_subgraph and informative_subgraph, preventing visibility into subgraph execution and state changes.

## Current Implementation
```python
for event in main_graph.stream(initial_state, stream_mode="updates", debug=True):
    initial_state.update(event) 

Solution

for event in main_graph.stream(initial_state, stream_mode="updates", debug=True, subgraphs=True):
    initial_state.update(event)

Impact

• No visibility into subgraph execution flow
• Unable to monitor/debug subgraph state changes
• Limited debugging and error tracing capabilities in production

[vbarda]

@YassinNouh21 subgraphs=True is the expected way to stream data from subgraphs, not sure what the issue is

also, initial_state.update(event) <-- this looks like an antipattern, you can just use stream_mode=values to get the final results (or if you used with checkpointer, main_graph.get_state(config))

[YassinNouh21]

@vbarda thank u for fast replying
Missing Subgraph Event Propagation in Parent Stream

Parent graph's stream doesn't propagate child graph events by default, losing visibility of nested executions.

# Current behavior
graph.stream(...) # Only parent events visible

# Expected behavior
graph.stream(..., subgraphs=True) # Parent + child events visible

[vbarda]

yes, that's the expected behavior, you should explicitly pass subgraphs=True if you want child events

[YGao119]

yes, that's the expected behavior, you should explicitly pass subgraphs=True if you want child events

I am having the same issue even though I have passed in subgraphs=True. I am calling subgraph in a node function. One possible cause of this I can think of is that I am using the same graphState for both parent and child graph (where the state has the same key, but the value is different during execution). Do you have any insight on why this could happen?

[YGao119]

To follow up and answer my question, the issue was, I set config for both main and sub graph when calling stream and invoke respectively. Then the sub graph's config related to Pregel app was not set up correctly.