[Bug] brew upgrade fails and rolls back on 3.1.0: lsregister postflight step exits with -10822

[JSB-Unscarred]

Description

Upgrading from 3.0.0 to 3.1.0 via Homebrew fails every time and Homebrew reverts the upgrade. The failure is in the postflight_steps block introduced in #182: the lsregister -f call exits with code 1.

Output

==> Moving App 'PureMac.app' to '/Applications/PureMac.app'
failed to scan /Applications/PureMac.app: -10822
from spotlight
Warning: Reverting upgrade for Cask puremac
Error: momenbasel/tap/puremac: Failure while executing; /usr/bin/env /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -f /Applications/PureMac.app exited with 1. Here's the output:
failed to scan /Applications/PureMac.app: -10822
from spotlight

What I checked

• Reproducible: retried several times, same result each time.
• The 3.1.0 zip matches the cask sha256, and codesign --verify --deep --strict passes.
• Running the exact same lsregister -f command manually from a terminal (on the installed app, and on a freshly extracted copy with the quarantine xattr set) succeeds with exit 0.
• Removing the postflight_steps block locally makes brew upgrade succeed.

So the step only fails when run by Homebrew's steps DSL, not on its own.

Suggestion

Since this step only refreshes the Dock/Launchpad icon cache (#111), a failure there probably shouldn't abort and roll back the whole install. Could it be made non-fatal (e.g. must_succeed: false or equivalent in the steps DSL), or dropped?

Environment

• macOS 27.0.1 (26A434), Apple Silicon (arm64)
• Homebrew 7.0.9
• Cask: momenbasel/tap/puremac 3.0.0 → 3.1.0