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Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.269 ·

Assistant thinking blocks get per-message memoized summary caching

Assistant 'thinking' text is now cached per message along with a reserved slot for a future summary

TierUnder the hoodhow much it should matter to you
Useful1my rating, 1 to 5
Signal1worth watching, 1 to 5
AreaTranscriptwhat it touches
KindInternal Changesin v2.1.269,
Under the hood

Assistant 'thinking' text is now cached per message along with a reserved slot for a future summary

What

The internal helper that pulls out an assistant message's thinking block (Claude's internal reasoning text, shown separately from its main reply) now caches the result per message instead of recomputing it every time. The cached record includes the thinking text, whether it's blank, and a reserved summary slot that isn't used yet.

Why

This is a performance and groundwork change: caching avoids redundant recomputation, and the reserved summary field suggests a future feature to show a condensed version of a thinking block, though that isn't active yet.

How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtThe `summary` slot is reserved but the finding doesn't say what will populate it or when.

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