Compaction

Summarizing history to make room

Library › Context Problems

1. The Context Window

2. Window Occupancy

3. Growth per Turn

4. Remaining Space

5. Turn Budget

6. Retrieval Footprint

7. Retrieval per Turn

8. Search Rounds

9. Window Sizing

10. Truncation

11. Compaction

12. The Compaction Bill

13. Compacted Retrieval

14. The Compaction Threshold

15. Verbatim Tail

16. Stateless API

17. Retrieval Cost

18. Context Tax

19. Quadratic Cost

20. Cost Forecast

Truncation throws the oldest turns away. Compaction keeps them, but small: the model reads the history and writes a summary that stands in for it. The system prompt is not part of the history and does not get compacted; it is pinned at the front and survives intact. So the window after a compaction is the same system prompt, followed by a summary a fraction of the size, and a great deal of space that was not there before.

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⬇ Compaction worksheet (3 pages)

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Next:
12. The Compaction Bill