Widening commit on top of the salvaged #9834: the same SSE parsing loop
class drops a final frame that is not newline-terminated (its bytes sit
in `buffer` at EOF and are discarded), and a clean EOF without [DONE]
was presented as a complete answer. Ported from earendil-works/pi#8997
(pi credited: Qiaochu Hu), which fixed the identical class in pi's
streamProxy.
- gateway/run_turn.py::_run_agent_via_proxy — flush the residual buffer
after the read loop; surface EOF-without-[DONE] (warn + error result
when nothing was received); extract _consume_sse_line so line parsing
and the EOF flush share one code path.
- agent/gemini_native_adapter.py::_iter_sse_events — same residual-buffer
flush via a shared _parse_sse_line helper.
- Tests: 3 invariants (residual flush x2 sites, EOF-without-DONE error),
proven red on origin/main.
11d761eed9