* fix(checkpoints): reject malformed Redis history write records
Validate pending-write tuples before optional Redis history entries reach
delta materialization. Treat the whole malformed entry as a miss so the
authoritative saver rebuilds it without dropping or inventing state.
Cover actual checkpoint reads, whole-entry replacement, valid tuple/list
records, neighbor preservation and warm-cache rereads.
* fix(checkpoints): bind cached history writes to their channel
* fix(checkpoints): keep cache warning failures best-effort
Guard warning handlers across decode, ingestion, serialization, Redis outages and purge. Preserve authoritative rebuilds and valid neighboring writes, with native graph regression coverage.
* docs(gateway): keep guidance below the hard size budget
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>