Long-running LLM work loses continuity: decisions, corrections, and constraints evaporate between sessions. Most fixes summarize old chats into a hidden prompt — invisible, unauditable, easy to poison. Memorist takes a different position: raw messages are evidence, not memory. Every message is preserved unchanged in a local ledger. Deterministic sentence segmentation produces units with exact character offsets, so every memory claim traces back to the exact words that produced it.