[BUG] Auto-updater ignores autoUpdatesChannel: "latest", actively downgrades to stable

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 auto-updater ignores the autoUpdatesChannel: "latest" setting in settings.json and actively downgrades from latest to stable channel versions. This is the inverse of #46145 (stable users getting latest).

Steps to Reproduce

1. Install Claude Code via native installer: curl -fsSL https://claude.ai/install.sh | bash -s -- latest → installs 2.1.100
2. Set "autoUpdatesChannel": "latest" and "autoUpdates": true in ~/.claude/settings.json
3. Launch Claude Code → confirms v2.1.100
4. Exit and relaunch → reverted to v2.1.89 (current stable)

The auto-updater re-downloads the stable version and swaps the symlink back:

$ ls -lat ~/.local/share/claude/versions/
-rwxr-xr-x  d  staff  196886384 Apr 10 07:51 2.1.89   # re-downloaded after deletion
-rwxr-xr-x  d  staff  200503760 Apr 10 07:35 2.1.100

Even deleting the old stable binary from ~/.local/share/claude/versions/ doesn't help — the updater fetches it again from the network and restores the symlink.

Workaround

Set "autoUpdates": false, manually force the symlink, and update manually:

curl -fsSL https://claude.ai/install.sh | bash -s -- latest
ln -sf ~/.local/share/claude/versions/2.1.100 ~/.local/bin/claude

Expected Behavior

With autoUpdatesChannel: "latest", the auto-updater should check the latest channel and update to the newest latest release — not downgrade to stable.

Environment

• macOS (Darwin 25.4.0, arm64)
• Installed via native installer (curl -fsSL https://claude.ai/install.sh | bash)
• Claude Code 2.1.100 (downgrades to 2.1.89)
• settings.json has "autoUpdatesChannel": "latest" and "autoUpdates": true

Related Issues

• #46145 — inverse bug: stable channel users getting updated to latest
• #45260 — auto-updater symlink issues
• #41140 — update notifications ignoring channel on macOS