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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 v2.1.54 Home All releases olderv2.1.53 v2.1.55newer
Claude Code v2.1.54

  • Fixed file open operations on Windows for bash command output: The bash command runner now opens its output log file using the portable string flag "w" (write) on Windows, instead of the bitwise POSIX flags O_WRONLY | O_CREAT | O_TRUNC, which may not behave correctly on Windows. Non-Windows platforms continue to use the POSIX flags with O_NOFOLLOW for symlink safety. (search for process.platform === "win32" in pj1 at line ~269290)
  • Fixed file open operations on Windows for task output appending: The task output writer class now opens files using the portable string flag "a" (append) on Windows, instead of the bitwise POSIX flags O_WRONLY | O_APPEND | O_CREAT. Previously, there was no Windows-specific handling in this code path. (search for process.platform === "win32" in class z31 at line ~130992)
  • Fixed file open operations on Windows for task output creation: The task output file creation function now uses the portable string flag "wx" (exclusive write) on Windows, instead of the bitwise POSIX flags O_WRONLY | O_CREAT | O_EXCL. This ensures exclusive-create semantics work correctly on Windows. (search for process.platform === "win32" in bq8 at line ~131075)

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 v2.1.54 →