[BUG] Multi-user macOS: Claude Code exits with code 1 when /private/tmp/claude-settings-<hash>.json is owned by a different UID

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The Claude Code child process exits with code 1 on macOS systems with multiple user accounts, because the app writes to /private/tmp/claude-settings-<hash>.json using a filename that is not keyed to the user's UID. The first user to run Claude Code creates this file owned by their UID with mode -rw-r--r--. When a second macOS user subsequently runs Claude Code, their child process fails on this file and exits with code 1, with no user-facing error message. Only a system reboot, or manually removing the file, clears the state.

What Should Happen?

Claude Code should either (a) include the UID in the settings filename (for example, /private/tmp/claude-<UID>/settings-<hash>.json, matching the pattern already used for the /private/tmp/claude-<UID>/ directory), or (b) use $TMPDIR, which macOS provides as a per-user path. Additionally, when the child process can't read or write expected state files, it should surface a clear error message instead of silently exiting with code 1.

Error Messages/Logs

[CCD] [replaceRemoteMcpServers] Calling SDK with 7 total servers [Claude in Chrome, mcp-registry, computer-use, Claude Preview, ccd_session, ccd_directory, scheduled-tasks]
[error] Session local_... query error: Claude Code process exited with code 1
  stack: 'Error: Claude Code process exited with code 1
    at sIr.getProcessExitError (.../index.js:390:8041)
    at ChildProcess.i (.../index.js:390:11086)
    at Object.onceWrapper (node:events:623:26)
    at ChildProcess.emit (node:events:520:35)
    at ChildProcess._handle.onexit (node:internal/child_process:294:12)'
[CCD CycleHealth] unhealthy cycle (0s, hadFirstResponse=false, reason=no_response)

Sentry event IDs:
b0a4cd30e958483890ba65596aefbdd5
7c7ac98e103448b6984d6cc1f0dc59bb
f0b561cb0a41497eaccd7501822fbf49
db751a5b7e474b94a1c17b780ecc7f3a
17506ad8f5164bbc86840281ac1270c4
1a03d131560d4028b411bc9696be1ca3

Steps to Reproduce

1. macOS machine with two user accounts (User A, UID 502; User B, UID 503). Both signed into Claude Desktop on the same Anthropic account.

1. User A opens Claude Desktop and starts a Claude Code session. This succeeds and creates:

• /private/tmp/claude-settings-<hash>.json (owned by UID 502, mode -rw-r--r--)
• /private/tmp/claude-502/ (owned by UID 502, contains working-directory state)

1. User A fully quits Claude Desktop via Cmd+Q. Verified via sudo ps aux and sudo launchctl list that no Claude processes or launchd jobs remain.

1. Switch to User B. Open Claude Desktop and start a Claude Code session.

1. Result: child process exits with code 1 immediately. No error shown to user.

Confirmed workaround (no reboot needed): sudo rm -rf /private/tmp/claude-*, then retry. User B's Claude Code session then works and creates its own /private/tmp/claude-503/.

Verified file ownership at the moment of reproduction:

$ ls -la /private/tmp/claude-*
-rw-r--r--  1 userA  wheel   2 Apr 24 15:23 /private/tmp/claude-settings-44136fa355b3678a.json

/private/tmp/claude-502:
drwxr-xr-x  3 userA  wheel  96 Apr 24 15:24 -Users-userA--myProject

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.3883.0 (93ff6c) 2026-04-21T17:24:01.000Z (bundled Claude Code: 2.1.111)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Extensively debugged before filing. Ruled out: skills plugin, MCP connectors (user-facing and internal), working directory, session state, keychain, auth, folder privacy permissions, and two-user process contention. All ruled out via sudo ps aux, sudo lsof, sudo launchctl list, and full resets of ~/Library/Application Support/Claude/ subdirectories. The /private/tmp/claude-settings-*.json ownership collision is the sole confirmed cause, and removal of that file is the sole required fix to restore function.

Full debugging session logs available on request.