StreamToolCalls

The tool calls seen so far in one stream, by their index.

A streamed tool call is split across deltas: the first carries its id, name and the start of its arguments, and each continuation carries only its index and the next argument fragment. Several calls can be interleaved, told apart by index. Continuations are given the id and name their index was first seen with, so the chunks a caller receives

• and the ones StreamingAccumulator, which keys calls by id and skips a chunk with none, accumulates - all name their call. (Before #1132 each client defaulted a missing id to "", and every continuation's arguments were dropped.)