When execute_code times out, the result JSON had status="timeout" and an
error field, but the output field was empty. Many models treat empty
output as "nothing happened" and produce an empty/minimal response. The
gateway stream consumer then considers the response "already sent" (from
pre-tool streaming) and silently drops it — leaving the user staring at
silence.
Three changes:
1. Include the timeout message in the output field (both local and remote
paths) so the model always has visible content to relay to the user.
2. Add periodic activity callbacks to the local execution polling loop so
the gateway's inactivity monitor knows execute_code is alive during
long runs.
3. Fix stream_consumer._send_fallback_final to not silently drop content
when the continuation appears empty but the final text differs from
what was previously streamed (e.g. after a tool boundary reset).
3e3ec35a5e