compact-budget-is-soft-cap
IN premise
The compact token budget is approximate; structural overhead (section headers, truncation messages) can cause up to ~25% overshoot beyond the specified budget.
Summary
When you set a target size for compacted output, the actual result can end up roughly 25% larger than requested because the system adds structural elements like section headers and truncation notices that don't count against the budget. This means you should plan for some overshoot when sizing compaction budgets, treating the number as a soft guideline rather than a hard ceiling.
Details
| Source | entries/2026/04/29/tests-test_compact.md |