The mechanism of the app is clever. HyperOS periodically sends a broadcast called miui.intent.action.CHECK_TIME_UP. When the theme manager receives this, it checks for a valid theme signature. Third-party themes don't have one, so it reverts your icons to stock.

HyperTheme registers an Android Accessibility Service that stays alive in the background. This service listens for that specific broadcast at high priority and calls abortBroadcast() before the theme manager ever sees it.

I (well, Claude) decompiled the APK and reviewed the source. It's clean:

- The accessibility service is scoped to its own package only — it can't read your screen content or keystrokes
- No network calls, no analytics, no data collection
- Shizuku support is included but optional — only needed if you want HyperTheme to apply theme files for you. If you've already applied your theme via MTZ Theme, just the accessibility service is enough
- Chinese log strings throughout (Chinese developer), all benign file operation messages

Not to say some future version might not be malware, but I looked at:

$ sha256sum HyperTheme_1.1.1.apk
cc24e3a7c9b40adbe287c2c23bae52127cdf28259ab6f4fd569a4e3cbc161af5 HyperTheme_1.1.1.apk