A failed turn keeps the calls that already ran as a bare pairing carrier, and
clipping the chain-of-thought off that carrier sent the call back to the API
with no reasoning at all — thinking mode refuses a call whose reasoning never
came back. The carrier keeps the reasoning and drops only the text.
A tool batch counted as committed only once every call had its result, so a
batch cut short was dropped whole and the retry ran tools that had already
had effects. Keep the calls that did report a result: their assistant row
stays as the pairing carrier (a request must answer every tool_calls id),
without the text of the unfinished turn, and the calls without a result are
absent so the retry re-issues them instead of assuming they ran. The kept
rows go to the store right away, and a failed rollback write is not allowed
to mask the failure being rolled back.