android-settings-wiringlisted

# Android Settings Wiring Lessons from auditing a production Android IME where most settings were inert. ## 1. A settings screen is not a settings system Bug: ~20 preferences rendered fine in the UI, but the keyboard consumer read only 3 of them at startup. Seventeen toggles did literally nothing — sliders, switches, all silently ignored. Nothing crashed; users just couldn't tell "off" from "broken". The gap is invisible from either end alone: the prefs XML looks done, the consumer code looks done. Only tracing key → read-site exposes it. **Fix:** for every `app:key` in preferences XML, grep the consumer for its read site. Any key with zero non-UI readers is a dead setting — wire it at one entry point (`onStartInputView` for IMEs, `onResume` for activities) or delete it. **Check:** script it: extract keys from XML, grep each against source minus the settings package. Zero hits = fail. ## 2. Toast-only handlers Bug: "Clear clipboard history" showed a success toast and deleted nothing — the click listener ended at `Toast.makeText(...)`. User believed data was gone; it wasn't. Worst kind of silent failure because it reports success. **Fix:** a destructive-action handler must perform the mutation (or visibly fail). If the handler contains no state change and no error path, it's a lie. **Check:** grep listeners for actions named delete/clear/reset/import; each body must touch storage or propagate an error. ## 3. Duplicate setters = JVM signature clash Adding a manual `