A thinking part is still being written iff it is the last content part of a response that is
still running: as soon as the answer text or a tool call arrives, a new part becomes the last
one. ThinkingChatResponseContent carries no completion flag of its own, and chunks are
merged into the existing part, so its position in the response is the reliable signal.
A thinking part is still being written iff it is the last content part of a response that is still running: as soon as the answer text or a tool call arrives, a new part becomes the last one.
ThinkingChatResponseContentcarries no completion flag of its own, and chunks are merged into the existing part, so its position in the response is the reliable signal.