A tool_use block name recorded by a stream attempt that died before any
visible text survived into the next attempt: only the deltas_were_sent
mid-tool branch cleared result["partial_tool_names"]. When the retry then
streamed plain text and dropped, the partial stub blamed the stale tool
("Stream stalled mid tool-call (old_tool)") and the stale name could make
a later attempt look mid-tool-call when deciding whether the drop is
retryable. Reset it in _start_stream_attempt alongside
provider_tool_in_flight, which already has attempt-local semantics.
Regression: two-attempt stream (tool_use start + parse error, then text +
drop) — stub content and emitted deltas carry no stale tool name.
kshitijk4poor
982e504262