Backfilled records need original timestamps, not import time

When you seed a searchable corpus from historical logs and then want to claim "this was already knowable when you hit it", that claim is a retrieval query restricted to records predating the event. If the write path stamps rows at import time, every backfilled row is simultaneous and the ordering the whole claim rests on is gone — and a schema DEFAULT now() tells you nothing, because what matters is whether the INSERT lets you override it. Second trap, quieter: retrieval must exclude records derived from the event's own source, or a note distilled from a session gets retrieved for that same session and appears to prove the corpus would have helped someone with their own discovery. That is circular, and it inflates results silently instead of failing.