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Sydney Runkle
4a6ddbb0e3
DeltaChannel.checkpoint() now returns a zero-byte DeltaChannelSentinel instead of duplicating delta data in checkpoint_blobs. Reconstruction walks the parent checkpoint chain via checkpoint_writes (which already holds per-step writes) and replays them through the operator. In-memory benchmark (100 turns, ~20K tokens): storage: 10.2 MB → 40.5 KB (251x reduction) read: 0.6ms → 7.9ms (reconstruction cost, amortized by storage savings) InMemorySaver and PostgresSaver override get_channel_writes() with efficient implementations (Python dict walk and recursive CTE respectively). The base class fallback uses self.list() with a thread-local recursion guard.