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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.55

5 entries read diff v2.1.54 → v2.1.55 Markdown

This is a small maintenance release focused on internal reliability improvements. File operations have been simplified to remove overly restrictive O_NOFOLLOW flags that could cause issues on setups with symbolic links, and session ID generation has been streamlined to use UUID-based identifiers.

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2 entries

Changesopen

Streamlined session ID generation#

Internal session identifiers (used for log files and remote agent tracking) now use UUID-based generation instead of custom random-byte character sampling. IDs are slightly shorter (6 hex characters from a UUID vs 8 base-36 characters from random bytes). Remote agent sessions now derive their ID directly from the parent session ID (search for "remote_agent") rather than generating an independent random ID, which improves traceability during debugging.

Evidence

Removed charset "0123456789abcdefghijklmnopqrstuvwxyz" (2 of 4 instances removed), replaced with randomUUID substring approach (search for replace(/-/g, "").substring(0, 6)).

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

1 entry

Notesopen

#

  • No new features, CLI flags, slash commands, environment variables, or feature flags were added in this release.
  • No breaking changes. All improvements are backward-compatible internal refinements.
  • Build number changed from 2160 to 2171.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Verbatim
Official · Anthropic

Anthropic’s official release notes

Published verbatim by Anthropic for v2.1.55. Text is unmodified from the upstream changelog. Everything else on this page came out of the bundle instead, which is why the two lists don't match.

  • Fixed BashTool failing on Windows with EINVAL error
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