When a model (e.g. mimo-v2-pro) streams intermediate text alongside tool
calls ("Let me search for that") but then returns empty after processing
tool results, the stream consumer already_sent flag is True from the
earlier text delivery. The gateway suppression check
(already_sent=True, failed=False → return None) would swallow the final
response, leaving the user staring at silence after the search.
Two changes:
1. gateway/run.py return path: skip already_sent suppression when the
final_response is "(empty)" or empty — the user needs to know the
agent finished even if streaming sent partial content earlier.
2. gateway/run.py response handler: convert the internal "(empty)"
sentinel to a user-friendly warning instead of delivering the raw
sentinel string.
Tests added for all empty/None/sentinel cases plus preserved existing
suppression behavior for normal non-empty responses.
e36c804bc2