Fix command execution permissions and eliminate backup error spam

- Add sudo permissions for systemctl and nixos-rebuild commands
- Use sudo in agent command execution for proper privileges
- Fix backup collector to handle missing status files gracefully
- Eliminate backup error spam when no backup system is configured

agent/src/agent.rs

@@ -253,7 +253,8 @@ impl Agent {
 
         info!("Executing systemctl {} {}", action_str, service_name);
 
-        let output = tokio::process::Command::new("systemctl")
+        let output = tokio::process::Command::new("sudo")
+            .arg("systemctl")
             .arg(action_str)
             .arg(service_name)
             .output()
@@ -293,7 +294,8 @@ impl Agent {
         }
 
         // Change to nixos directory and execute rebuild
-        let output = tokio::process::Command::new("nixos-rebuild")
+        let output = tokio::process::Command::new("sudo")
+            .arg("nixos-rebuild")
             .arg("switch")
             .current_dir(nixos_path)
             .output()

agent/src/collectors/backup.rs

@@ -24,7 +24,12 @@ impl BackupCollector {
         }
     }
 
-    async fn read_backup_status(&self) -> Result<BackupStatusToml, CollectorError> {
+    async fn read_backup_status(&self) -> Result<Option<BackupStatusToml>, CollectorError> {
+        // Check if backup status file exists
+        if !std::path::Path::new(&self.backup_status_file).exists() {
+            return Ok(None); // File doesn't exist, but this is not an error
+        }
+
         let content = fs::read_to_string(&self.backup_status_file)
             .await
             .map_err(|e| CollectorError::SystemRead {
@@ -32,10 +37,12 @@ impl BackupCollector {
                 error: e.to_string(),
             })?;
 
-        toml::from_str(&content).map_err(|e| CollectorError::Parse {
+        let backup_status = toml::from_str(&content).map_err(|e| CollectorError::Parse {
             value: "backup status TOML".to_string(),
             error: e.to_string(),
-        })
+        })?;
+
+        Ok(Some(backup_status))
     }
 
     fn calculate_backup_status(&self, backup_status: &BackupStatusToml) -> Status {
@@ -105,10 +112,27 @@ impl Collector for BackupCollector {
     }
 
     async fn collect(&self, _status_tracker: &mut StatusTracker) -> Result<Vec<Metric>, CollectorError> {
-        let backup_status = self.read_backup_status().await?;
+        let backup_status_option = self.read_backup_status().await?;
         let mut metrics = Vec::new();
         let timestamp = chrono::Utc::now().timestamp() as u64;
 
+        // If no backup status file exists, return minimal metrics indicating no backup system
+        let backup_status = match backup_status_option {
+            Some(status) => status,
+            None => {
+                // No backup system configured - return minimal "unknown" metrics
+                metrics.push(Metric {
+                    name: "backup_overall_status".to_string(),
+                    value: MetricValue::String("no_backup_system".to_string()),
+                    status: Status::Unknown,
+                    timestamp,
+                    description: Some("No backup system configured (no status file found)".to_string()),
+                    unit: None,
+                });
+                return Ok(metrics);
+            }
+        };
+
         // Overall backup status
         let overall_status = self.calculate_backup_status(&backup_status);
         metrics.push(Metric {