agent-signals

062. CODEX_HOME moves all files of Codex CLI, also on Windows

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Date
2026-10-31
Agents
Codex CLI
Measured on
CI runner ubuntu-22.04, ubuntu-24.04, ubuntu-26.04 (x64); CI runner ubuntu-22.04-arm, ubuntu-24.04-arm, ubuntu-26.04-arm (arm64); CI runner macos-15, macos-26 (arm64); CI runner macos-15-intel, macos-26-intel (x64); CI runner windows-2022, windows-2025 (x64) and windows-11-arm (arm64)

Measured

2026-10-31, Codex CLI 0.166.0 from npm @openai/codex, in the scenarios workflow (run 41151440753, and before it run 41149533184). The scenario name codex-home starts codex with CODEX_HOME=<throwaway folder>/.codex. That folder is next to the throwaway home, not in it, so that a file in it cannot be a file of the default ~/.codex. The scenario makes the folder before the start. On Linux and macOS the run is scenarios/first-run.sh codex-home codex. On Windows the run is scenarios/first-run-windows.py codex-home codex, before the normal codex run of the same job, with USERPROFILE, HOME, APPDATA, LOCALAPPDATA, TEMP and TMP in the throwaway folder as in fact 53.

Measured on: CI runner ubuntu-22.04, ubuntu-24.04, ubuntu-26.04 (x64); CI runner ubuntu-22.04-arm, ubuntu-24.04-arm, ubuntu-26.04-arm (arm64); CI runner macos-15, macos-26 (arm64); CI runner macos-15-intel, macos-26-intel (x64); CI runner windows-2022, windows-2025 (x64) and windows-11-arm (arm64).

What was measured

  1. On each Linux and macOS label, Codex CLI made no file below the throwaway HOME. It made 5,504 files in the CODEX_HOME folder on Linux and on macos-15, and 5,505 on the other three macOS labels: the same names as in ~/.codex of the normal run (fact 29): config.toml, installation_id, version.json, .tmp/plugins (about 5,400 files), skills/.system, tmp/ (on Linux tmp/arg0-linux/), and the SQLite files state_5, logs_2, goals_1, memories_1 and queue_1, each with -wal and -shm.
  2. On Linux the process held the five SQLite files with -wal and -shm and tmp/arg0-linux/codex-arg0<random>/.lock open, all in the CODEX_HOME folder.
  3. On the three Windows images, Codex CLI made 5,507 files in the CODEX_HOME folder: the same names, .sandbox, and three files in tmp. It made 0 changes in the real profile on windows-2022 and windows-2025. On windows-11-arm the one change was %LOCALAPPDATA%\Packages, which also changes with no agent (fact 55).
  4. In the same jobs, the normal codex run after it made 22 changes in the real profile on windows-2022 and windows-2025, and 23 on windows-11-arm: the real %USERPROFILE%\.codex of fact 53.
  5. The first screen was the same as with no CODEX_HOME (fact 52).
  6. On Windows, the driver could not delete the throwaway folder after the codex-home run ("could not delete the throwaway folder"). The processes below the driver were stopped before that.

Mechanism

Codex CLI takes its folder from CODEX_HOME when the variable is set, and from the profile folder of the account when it is not set. On Windows, the profile folder comes from Windows, not from USERPROFILE or HOME (fact 53). CODEX_HOME is the one variable that keeps Codex CLI out of the real profile on Windows.

A tool that looks for the Codex files of a session must read CODEX_HOME from the environment of the process first, and use ~/.codex only when the variable is not set.

Incident

Before this fact, each Windows first run wrote a Codex state into the real profile of the runner (fact 53). The codex-home run does not.

Screens

None. The screen is the screen of fact 52.

Not measured