agent-signals

071. A Windows update renames the running program of Claude Code and agy

View as Markdown Open in Claude Open in ChatGPT
Date
2026-10-31
Agents
Claude Code, Antigravity CLI
Measured on
real machine

Measured

2026-10-31, Claude Code 2.1.314 and Antigravity CLI (agy) 1.4.12, on Windows 11 Pro 10.0.26300 (x64). The probe kit (probes/run.ps1) listed the install folders with names, sizes and times, and the processes. Measured on: real machine.

What was measured

  1. ~\.local\bin\ held claude.exe (2.1.314) and two files of the form claude.exe.old.<Unix time in ms>.<pid>. In one of them, <pid> was the pid of a Claude process that still ran. That process started 9 days before the probe.
  2. ~\.local\share\claude\versions\ held 2.1.311, 2.1.312 and 2.1.314 as single files. The size of each .old file was the size of one of these versions.
  3. ~\AppData\Local\agy\bin\ held agy.exe and two files of the form agy.exe.<hex>.old.
  4. The Claude process that started 9 days before the probe had a pid file with version of its own, older version (see fact 066). Two Claude pid files existed, one for each live process. They had the same keys as on macOS and Linux, and no tmux key.
  5. A third claude.exe ran as chrome.exe > cmd.exe > claude.exe --chrome-native-host, with no pid file, as on Ubuntu (fact 066).

Mechanism

Windows does not let a program replace the file of a running program, but it lets the program rename the file. The updater renames the old file and writes the new file in its place. The name keeps the pid of the process that ran the old file. The .old files stay after that process stops.

A reader can take the version of a live process from its pid file. The file claude.exe gives only the newest version.

Incident

None.

Screens

None.

Not measured