Source Intelligence

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.

All of v2.1.55 Home All releases olderv2.1.54 v2.1.56newer
Claude Code v2.1.55

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.

See this entry in the whole of v2.1.55 →