Set aside this lane's old tool output
Takes the model-facing text of old tool results out of this lane’s window — a file read from forty rounds ago that is re-sent verbatim on every round since. It sends no model round, so it costs nothing, and it summarises nothing away: the conversation keeps every word, the transcript keeps every result, and only what the model re-reads shrinks.
The cheap gesture of the pair, and the one to reach for first. What is set aside stays out of the window durably, so this is a decision rather than a hint the next round recomputes.
The newest results are never taken — an agent that loses the result it is about to act on has lost the plot — and neither is anything small enough that the trade is not worth a permanent hole in what the model remembers.
How many results were set aside travels on the context-pruned event, not in this response: a second client watching the same lane must learn the same fact through the same channel, whether the prune came from here or from the host’s own threshold.
Answers 409 when a turn is running on the lane, and 409 when nothing in the window is eligible.

