Two tests asserted the old behaviour where completed nodes/DAGs stayed
in the snapshot. Under the redesign, Done nodes are filtered off the wire
(a fully-Done DAG disappears; a Failed one lingers + is history-capped):
- failed_node test: the completed reconcile is Done → assert it's absent,
not Done-present (its run is already verified by the claim).
- history-eviction test: fail the nodes so the DAGs linger (Done ones
would vanish), then assert the grace window + per-template cap.
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