Event Time vs Ingestion Time

Two different clocks. Event time is when a fact was true in the world; ingestion time is when the system learned it. They routinely differ, and sometimes in the same sentence.

Why it matters in a memory layer

One timestamp is a bug you cannot fix retroactively. "Before the move I used to cycle to work" arrives in 2026 and is about 2025 — collapse the two clocks and the system believes she cycles now. Recording both is nearly free at write time and impossible to reconstruct afterwards.

Connections

Taught in: Designing the Memory Record

Used in: Two Clocks · Deterministic Arbitration