Prior-turn memory: lightweight continuity

The model needs to remember what it did, even if not the full content. A cheap, effective technique: after each turn, summarise the turn's actions into a short note ("generated draft.docx → doc-1; read source.docx → doc-0") and inject that summary into the next call. This gives the model continuity, it knows the handles for things it produced and won't redo work, without re-sending everything. It's a tiny amount of context for a large coherence gain.