Fix disk collector to use dynamic device detection

- Remove underlying_devices field from FilesystemConfig
- Add device detection at startup using findmnt command
- Store detected devices in HashMap for reuse during collection
- Keep all existing functionality (StoragePool, DriveInfo, SMART data)
- Detect devices only once at initialization, not every collection cycle
- Fixes agent startup failure due to missing underlying_devices config

agent/src/collectors/disk.rs

@@ -36,6 +36,7 @@ struct DriveInfo {
 pub struct DiskCollector {
     config: DiskConfig,
     temperature_thresholds: HysteresisThresholds,
+    detected_devices: std::collections::HashMap<String, Vec<String>>, // mount_point -> devices
 }
 
 impl DiskCollector {
@@ -48,9 +49,20 @@ impl DiskCollector {
             5.0,  // 5°C gap for recovery
         );
         
+        // Detect devices for all configured filesystems at startup
+        let mut detected_devices = std::collections::HashMap::new();
+        for fs_config in &config.filesystems {
+            if fs_config.monitor {
+                if let Ok(devices) = Self::detect_device_for_mount_point_static(&fs_config.mount_point) {
+                    detected_devices.insert(fs_config.mount_point.clone(), devices);
+                }
+            }
+        }
+        
         Self { 
             config,
             temperature_thresholds,
+            detected_devices,
         }
     }
 
@@ -84,8 +96,9 @@ impl DiskCollector {
                     let used = self.bytes_to_human_readable(used_bytes);
                     let available = self.bytes_to_human_readable(available_bytes);
 
-                    // Get individual drive information
+                    // Get individual drive information using pre-detected devices
-                    let underlying_drives = self.get_drive_info_for_devices(&fs_config.underlying_devices)?;
+                    let device_names = self.detected_devices.get(&fs_config.mount_point).cloned().unwrap_or_default();
+                    let underlying_drives = self.get_drive_info_for_devices(&device_names)?;
 
                     storage_pools.push(StoragePool {
                         name: fs_config.name.clone(),
@@ -249,6 +262,27 @@ impl DiskCollector {
         }
     }
 
+    /// Detect device backing a mount point using findmnt (static version for startup)
+    fn detect_device_for_mount_point_static(mount_point: &str) -> Result<Vec<String>> {
+        let output = Command::new("findmnt")
+            .args(&["-n", "-o", "SOURCE", mount_point])
+            .output()?;
+        
+        if !output.status.success() {
+            return Ok(Vec::new());
+        }
+        
+        let output_str = String::from_utf8_lossy(&output.stdout);
+        let device_path = output_str.trim();
+        
+        // Extract device name from path (e.g., /dev/nvme0n1 -> nvme0n1)
+        if let Some(device_name) = device_path.strip_prefix("/dev/") {
+            Ok(vec![device_name.to_string()])
+        } else {
+            Ok(Vec::new())
+        }
+    }
+
     /// Get directory size using du command (efficient for single directory)
     fn get_directory_size(&self, path: &str) -> Result<u64> {
         let output = Command::new("du")

agent/src/config/mod.rs

@@ -86,7 +86,6 @@ pub struct FilesystemConfig {
     pub fs_type: String, // "ext4", "zfs", "xfs", "mergerfs", "btrfs"
     pub monitor: bool,
     pub storage_type: String, // "single", "raid", "mirror", "mergerfs", "zfs"
-    pub underlying_devices: Vec<String>, // ["sda", "sdb", "sdc"] or ["nvme0n1"]
 }