Compaction Headroom Reservation (~16.5%)

Description

Structural property that ~16.5% of the 200K Claude Code context window is permanently reserved as a compaction buffer. Auto-compaction fires at roughly 167K context tokens (83% of 200K), so the functional window users actually operate within is ~167K even though the nominal window is 200K. Hidden compaction reads ~167K and emits summary output that is logged nowhere in the transcript.

Key claims

Relations

Sources

src-20260409-e32facfa1c9f