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+# pad_scanner CLAUDE.md
+
+## App Installation Rules
+
+**Always use `adb install -r` to install the app. Never use `flutter install`.**
+
+`flutter install` uninstalls the old version first, which wipes app configuration (API URL, sound file paths, etc.). `adb install -r` performs an in-place upgrade that preserves all app data.
+
+### Installation Steps
+
+```bash
+# 1. Build
+flutter build apk --release
+
+# 2. Install (in-place upgrade, preserves config)
+adb install -r build/app/outputs/flutter-apk/app-release.apk
+```