MEMORY HIERARCHIES FOR CONTEXT

TIER-MOVEMENT RULES Good designs state their movement rules explicitly, so that the behavior is predictable. Here is a sample set of rules in plain language for a long-running agent. Rule one: every message begins in the hot tier. Rule two: when the hot tier reaches 75 percent of its budget, summarize the oldest half and store the summary in the warm tier, and copy the originals to the cold tier. Rule three: the notes file is never summarized, and is re-read in full at the start of every session. Rule four: tool results larger than 2,000 tokens are saved to the cold tier immediately, and only a short pointer plus key lines enter the hot tier. Rule five: summaries unused for thirty days are archived, but stay searchable. Rule six: on any question about earlier work, search warm summaries first, then retrieve cold detail only if the summary is insufficient. Rules like these can be written down, reviewed, tested, and tuned, which is far better than leaving the behavior to chance.