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Sweep 02 Oct 2026 · 18:55Z Build v2.1.288 509 read Stable v2.1.285 Latest v2.1.288 Next v2.1.288 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.288 ·

Small internal additions: an attachment prefetch header and saved-item fields

Claude Code gains a new attachment prefetch request header, two new fields on saved items, and a few small error-handling tweaks

Under the hood Internal Changes
JSON All of v2.1.288
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
SessionsArea: what it touches
Internal ChangesKind: in v2.1.288,
Internal ChangesSection of the release
What

This release makes several small internal changes:

  • A request header, x-anthropic-attachment-prefetch-seen: 1, now exists. A request header is a short label attached to a message sent over the network.
  • Saved items can now record two extra optional values, titleSha and usedAt.
  • A usage report that confirms a feature is working can no longer stop Claude Code if it fails.
  • When Claude Code counts the changed lines in a diff (a comparison showing what changed in a file), a diff it refused to produce now counts as zero lines.
Why

These are behind-the-scenes changes. You are unlikely to notice any difference day to day.

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 doubtIt is not clear which requests carry the new attachment prefetch header.

See this entry in the whole of v2.1.288 →

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