{"version":"2.1.288","anchor":"precomputed-compaction-reuse-now-checks-coverage-and-fit","canonical_anchor":"precomputed-compaction-reuse-now-checks-coverage-and-fit","heading":"Precomputed compaction summaries are checked for coverage and fit before reuse","tier":"soon","area":"Compaction","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.288\/e\/precomputed-compaction-reuse-now-checks-coverage-and-fit","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.288","markdown":"### Precomputed compaction summaries are checked for coverage and fit before reuse\n\nBefore reusing a summary prepared in advance, auto-compact now checks it still covers the conversation and fits, and refuses it with a named reason if not\n\n**Unclear.** It is not clear whether preparing summaries in advance runs for anyone, since its setting is only shown when a server-side switch allows it.\n\n**What**\n\nCompaction is when Claude Code shrinks a long conversation into a summary so it fits the model's context window. Sometimes that summary is prepared in advance. Before reusing it, Claude Code now checks that it still covers the conversation and still fits:\n\n- Reuse can now be refused with named reasons, including `rows_unreadable` and `would_not_fit`.\n\n- Loading a prepared summary back from disk no longer rejects it for `grew_too_much`. It now checks `modelMatch`, `preservedUuidCount` and `rows_unreadable` instead.\n\n- The discard log now includes token sizes, and saved summaries record `preservedMessageCount` and `preservedUuidCount`.\n\nThe related gate `tengu_sepia_moth` was off for this site's account and for the anonymous baseline in earlier readings, but no reading has been taken under this release.\n\n**Why**\n\nAuto-compact should be less likely to swap in a prepared summary that is out of date or that would push the conversation over its size limit.\n\n- Flag `tengu_sepia_moth`: Off in both readings (read for one account on one subscription tier against v2.1.288; this account: off, anonymous baseline: off, compiled default: off) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: Compaction\n- Tier: Nothing to try yet\n- Useful: 3\/5\n- Signal: 4\/5\n- Scope: individual\n- Heads-up: no\n- Present in the build but not switched on"}