reasoning_think emits with Role:tool producing [[[tool:reasoning_think]]]...[[[end]]]
blocks. When followed by the model's text response ([[[text]]]...[[[end]]]),
the chat log gets two [[[end]]] markers per turn, breaking the state machine
parser.
Fix: check for ev.Name == "reasoning_think" in the tool case and suppress
it the same way as the reasoning role — set streamingRole and return without
writing to the log.
962a1ec654