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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.

← All of v2.1.251 Home All releases ←olderv2.1.250
Claude Code v2.1.251

Write and NotebookEdit re-check the file just before writing

You'll notice
Useful4 Signal3
File Tools

Write and NotebookEdit re-read the file right before writing to avoid clobbering changes.

What

Both tools now hold an open handle, read the current contents and re-check them immediately before the write lands, narrowing the window in which a file could change between being read and being overwritten.

Details
  • the handle is closed once the write completes
  • applies to every Write and NotebookEdit call, with no setting involved
Evidence

recheckBeforeWrite

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 v2.1.251 →