[adityasingh2400]

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Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: BuiltInCodeExecutor emits an empty final event before every model reply #7878

Problem:
For BuiltInCodeExecutor, the code execution response processor always yielded an Event(actions=event_actions). When the response had no image to save, that event had no content and empty actions. is_final_response() still returned True for it, and it was stored in the session.

So every reply came with an empty "final" event in front of it. A run loop that stops at the first final response, as is_final_response() is documented to support, got nothing back (#4138).

Solution:
The event is only yielded when event_actions.artifact_delta is non-empty, i.e. when an image was actually saved as an artifact. The image path is unchanged:

• artifacts are saved;
• the parts are rewritten to "Saved as artifact: …";
• the event carries the artifact_delta.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Added test_builtin_code_executor_emits_no_event_without_images to tests/unittests/flows/llm_flows/extensions/test_code_execution.py, next to test_builtin_code_executor_image_artifact_creation. A text-only response yields no events, saves no artifact, and leaves the parts unchanged.

# On main (before the fix)
AssertionError: assert [Event(model_...)] == []
  Left contains one more item: Event(model_version=None, content=None, ...)

# With the fix
$ pytest tests/unittests/flows
1197 passed

pre-commit run passes on the changed files.

Manual End-to-End (E2E) Tests:

I ran InMemoryRunner with LlmAgent(code_executor=BuiltInCodeExecutor()) and a mock model that answers "The answer is 42.":

=== BEFORE (main) ===
'a' content= None actions= {'state_delta': {}} final= True
'a' content= parts=[Part(text='The answer is 42.')] ... final= True
session events: 3 [('user', True), ('a', False), ('a', True)]

=== AFTER (this PR) ===
'a' content= parts=[Part(text='The answer is 42.')] ... final= True
session events: 2 [('user', True), ('a', True)]

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

#4138 was closed after the reporter worked around this, but the empty event is still emitted on main.