The original code's strategy of intercepting the finishChunk was absolutely correct in principle. The failure was in the mechanism it used to decide when to release that chunk. It was a manual, fragile system that broke under specific timing conditions.
Think of it like a relay race with two runners who need to finish at the same time.
- Runner A: The Tool Executor. Its job is to run the tool and report back.
- Runner B: The Model Stream. Its job is to send all its data and then signal that it's done.
- The Finish Line: The
attemptClose()function, which is supposed to end the step. - The Rule: The step can only end when both runners are at the finish line.
The problem is that the two runners were not properly synchronized. They were checking for each other's status using separate flags (canClose and outstandingToolResults.size).