atl upgrade

Update the atl binary itself to the latest stable release: resolve the newest published release, and if it is newer than the running build, download it, verify its checksum, and atomically replace this binary in place.

atl upgrade is the manual surface for keeping the binary current. You rarely need it — once the hooks are set up, atl session-start runs the same check automatically (see Automatic upgrades). Reach for it to force an immediate update.

Binary vs. teams

atl upgrade updates the binary. atl update updates your installed teams and reflects the platform core into ~/.claude. They are separate surfaces: the binary is a released artifact, teams are content.

Usage

atl upgrade

It takes no arguments and no flags.

What it does

1. Resolve the latest stable release. Queries GitHub for the newest stable release (prereleases are excluded).
2. Compare — only upgrade, never downgrade. If the running build is not strictly older than the latest release, it is a no-op (already up to date). A dev build (an un-stamped local go build) is left untouched.
3. Download + verify. Fetches the release asset for your OS/architecture and its published checksums.txt, and verifies the download's SHA-256 before touching the install directory.
4. Atomically replace the running binary. Writes the new binary beside the current one and renames it into place, so an interrupted update never leaves a half-written binary. The running process keeps executing the old copy; the next invocation is the new version.

Automatic upgrades

With the hooks installed, atl session-start performs this same check on your behalf — throttled to at most once every 24 hours. When a newer release exists, it starts the download and swap in the background (it never blocks the session) and prints a one-line notice; the new binary is active from the next session. This is automatic and mandatory — there is no per-project opt-in.

Disabling it

Set ATL_NO_SELF_UPDATE (to any value) to disable self-update entirely — both the manual command and the automatic session-start check become no-ops. This is an emergency brake (for example, if a release is misbehaving); the feature is otherwise always on.

ATL_NO_SELF_UPDATE=1 atl upgrade   # → disabled, does nothing

Platform notes

• macOS / Linux — full support (in-place atomic replace).
• Windows — a running .exe can't overwrite itself, so atl upgrade reports the newer version and asks you to rerun the install script instead; the automatic check notifies rather than swapping.
• Permissions — if the install directory isn't writable (for example a system path installed with sudo), the upgrade reports a clear error rather than silently escalating. Reinstall with the install script, or point it at a user-writable directory with ATL_INSTALL_DIR.

See also

• atl update — refresh installed teams (not the binary).
• atl setup-hooks — wire the hooks that run the automatic check.
• Installation — the install script (the other way to upgrade the binary).