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 v2.1.242 Home All releases olderv2.1.241 v2.1.243newer
Claude Code v2.1.242

Only one Claude Code window per machine syncs a given session

You'll notice
Useful3 Signal2
Directory Sync

If the same session is open twice, only one window syncs files.

What

File sync now takes a lock before writing, so if you have the same session open in two windows only the first one syncs. The second says so and stays quiet instead of both writing at once.

Details
  • The lock is a file under a writer-locks directory keyed to the session's side repository.
  • If a window's lock is taken over or lost while it held it, sync stops in that window with an explicit message rather than continuing blind.
  • If the process stalls long enough to be caught by the interval check, the lock is re-taken and cached state is thrown away rather than assumed to still be valid.
Evidence

Another Claude Code window on this machine is syncing this session's files; this one won't

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

Related

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

See this entry in the whole of v2.1.242 →