diff --git a/src-tauri/src/ble/utils.rs b/src-tauri/src/ble/utils.rs
index 13ba48f..35ed7a6 100644
--- a/src-tauri/src/ble/utils.rs
+++ b/src-tauri/src/ble/utils.rs
@@ -7,3 +7,36 @@ pub fn normalize_uuid(u: &str) -> String {
     }
     s
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_strips_standard_base_suffix() {
+        assert_eq!(normalize_uuid("00001816-0000-1000-8000-00805f9b34fb"), "1816");
+    }
+
+    #[test]
+    fn test_short_uuid_is_unchanged() {
+        assert_eq!(normalize_uuid("1816"), "1816");
+    }
+
+    #[test]
+    fn test_trims_whitespace() {
+        assert_eq!(normalize_uuid(" 1816 "), "1816");
+    }
+
+    #[test]
+    fn test_lowercases_input() {
+        assert_eq!(normalize_uuid("181D"), "181d");
+    }
+
+    #[test]
+    fn test_custom_128bit_uuid_is_left_untouched() {
+        assert_eq!(
+            normalize_uuid("f0001816-0451-4000-b000-000000000000"),
+            "f0001816-0451-4000-b000-000000000000"
+        );
+    }
+}
diff --git a/src-tauri/src/device/mod.rs b/src-tauri/src/device/mod.rs
index 9277d58..a3e6903 100644
--- a/src-tauri/src/device/mod.rs
+++ b/src-tauri/src/device/mod.rs
@@ -93,6 +93,23 @@ pub fn get_device_types(device: &Device) -> Vec<DeviceType> {
 mod tests {
     use super::*;
 
+    /// Test helper: builds a Device from service UUIDs and characteristics,
+    /// with all other fields stubbed. Tests only exercise classification.
+    fn dev(services: &[&str], characteristics: &[&str]) -> Device {
+        Device {
+            id: "test-device".into(),
+            address: "00:00:00:00:00:00".into(),
+            display_name: None,
+            rssi: None,
+            service_uuids: services.iter().map(|s| s.to_string()).collect(),
+            characteristics: characteristics.iter().map(|s| s.to_string()).collect(),
+            manufacturer_data: None,
+            metadata: None,
+        }
+    }
+
+    // Real-device fixture: Magene speed/cadence sensor advertising the CSC
+    // service (0x1816) as a full 128-bit UUID.
     #[test]
     fn test_service_types_for_magene_speedcadence() {
         let magene = Device {
@@ -108,4 +125,101 @@ mod tests {
 
         assert_eq!(get_device_types(&magene), [DeviceType::CadSensor]);
     }
+
+    // Heart rate
+    #[test]
+    fn test_hr_sensor_by_service() {
+        assert_eq!(get_device_types(&dev(&["180d"], &[])), [DeviceType::HrSensor]);
+    }
+
+    #[test]
+    fn test_hr_sensor_by_characteristic() {
+        assert_eq!(get_device_types(&dev(&[], &["2a37"])), [DeviceType::HrSensor]);
+    }
+
+    #[test]
+    fn test_hr_sensor_by_full_128bit_uuid() {
+        assert_eq!(
+            get_device_types(&dev(&["0000180d-0000-1000-8000-00805f9b34fb"], &[])),
+            [DeviceType::HrSensor]
+        );
+    }
+
+    // Cadence / speed
+    #[test]
+    fn test_cadence_by_service() {
+        assert_eq!(get_device_types(&dev(&["1816"], &[])), [DeviceType::CadSensor]);
+    }
+
+    #[test]
+    fn test_cadence_by_characteristic() {
+        assert_eq!(get_device_types(&dev(&[], &["2a5b"])), [DeviceType::CadSensor]);
+    }
+
+    // Trainer / cycling power / FTMS
+    #[test]
+    fn test_trainer_by_ftms_service() {
+        assert_eq!(get_device_types(&dev(&["1826"], &[])), [DeviceType::Trainer]);
+    }
+
+    #[test]
+    fn test_trainer_by_power_service() {
+        assert_eq!(get_device_types(&dev(&["1818"], &[])), [DeviceType::Trainer]);
+    }
+
+    #[test]
+    fn test_trainer_by_power_characteristic() {
+        assert_eq!(get_device_types(&dev(&[], &["2a63"])), [DeviceType::Trainer]);
+    }
+
+    #[test]
+    fn test_trainer_by_fitness_machine_characteristic() {
+        assert_eq!(get_device_types(&dev(&[], &["2acc"])), [DeviceType::Trainer]);
+    }
+
+    // Indoor bike data (2ADx): a trainer characteristic that also implies cadence.
+    #[test]
+    fn test_indoor_bike_data_is_trainer_and_cadence() {
+        // 2ad2 is both a trainer characteristic and an indoor-bike marker.
+        assert_eq!(
+            get_device_types(&dev(&[], &["2ad2"])),
+            [DeviceType::Trainer, DeviceType::CadSensor]
+        );
+    }
+
+    #[test]
+    fn test_indoor_bike_variant_is_cadence_only() {
+        // 2ad5 is an indoor-bike marker but not in the trainer list.
+        assert_eq!(get_device_types(&dev(&[], &["2ad5"])), [DeviceType::CadSensor]);
+    }
+
+    // "service::characteristic" strings produced by the scanner.
+    #[test]
+    fn test_characteristic_split_on_double_colon() {
+        assert_eq!(get_device_types(&dev(&[], &["1816::2a5b"])), [DeviceType::CadSensor]);
+    }
+
+    // Combined and negative cases
+    #[test]
+    fn test_hr_and_cadence_combo() {
+        assert_eq!(
+            get_device_types(&dev(&["180d", "1816"], &[])),
+            [DeviceType::HrSensor, DeviceType::CadSensor]
+        );
+    }
+
+    #[test]
+    fn test_battery_service_is_ignored() {
+        assert!(get_device_types(&dev(&["180f"], &[])).is_empty());
+    }
+
+    #[test]
+    fn test_empty_device_has_no_types() {
+        assert!(get_device_types(&dev(&[], &[])).is_empty());
+    }
+
+    #[test]
+    fn test_uuid_case_and_whitespace_are_normalized() {
+        assert_eq!(get_device_types(&dev(&[" 180D "], &[])), [DeviceType::HrSensor]);
+    }
 }
diff --git a/src-tauri/src/device_repo/repo.rs b/src-tauri/src/device_repo/repo.rs
index 096bd34..94aa018 100644
--- a/src-tauri/src/device_repo/repo.rs
+++ b/src-tauri/src/device_repo/repo.rs
@@ -60,6 +60,20 @@ pub fn repo_from_devices(devices: Vec<Device>) -> Repo {
 mod tests {
     use super::*;
 
+    /// Helper: a cadence device (CSC service 0x1816) with the given RSSI.
+    fn cadence_device(rssi: Option<i16>) -> Device {
+        Device {
+            id: format!("cad-{rssi:?}"),
+            address: "00:00:00:00:00:00".into(),
+            display_name: None,
+            rssi,
+            service_uuids: vec!["1816".into()],
+            characteristics: vec![],
+            manufacturer_data: None,
+            metadata: None,
+        }
+    }
+
     #[test]
     fn test_repo_classifies_magene_as_cadence_sensor() {
         let magene = Device {
@@ -79,4 +93,42 @@ mod tests {
         assert!(repo.hr_sensors.is_empty());
         assert!(repo.trainers.is_empty());
     }
+
+    #[test]
+    fn test_sorts_devices_by_rssi_descending() {
+        let devices = vec![
+            cadence_device(Some(-80)),
+            cadence_device(Some(-42)),
+            cadence_device(Some(-60)),
+        ];
+        let repo = repo_from_devices(devices);
+        let rssis: Vec<_> = repo.cad_sensors.iter().map(|d| d.rssi).collect();
+        assert_eq!(rssis, vec![Some(-42), Some(-60), Some(-80)]);
+    }
+
+    #[test]
+    fn test_devices_without_rssi_go_last() {
+        let devices = vec![cadence_device(None), cadence_device(Some(-50))];
+        let repo = repo_from_devices(devices);
+        assert_eq!(repo.cad_sensors[0].rssi, Some(-50));
+        assert_eq!(repo.cad_sensors[1].rssi, None);
+    }
+
+    #[test]
+    fn test_indoor_bike_lands_in_trainer_and_cadence_buckets() {
+        let indoor_bike = Device {
+            id: "indoor-bike".into(),
+            address: "00:00:00:00:00:00".into(),
+            display_name: None,
+            rssi: Some(-70),
+            service_uuids: vec![],
+            characteristics: vec!["2ad2".into()],
+            manufacturer_data: None,
+            metadata: None,
+        };
+        let repo = repo_from_devices(vec![indoor_bike]);
+        assert_eq!(repo.trainers.len(), 1);
+        assert_eq!(repo.cad_sensors.len(), 1);
+        assert!(repo.hr_sensors.is_empty());
+    }
 }