diff --git a/deno.json b/deno.json
index 4ee8f16..f792084 100644
--- a/deno.json
+++ b/deno.json
@@ -1,6 +1,6 @@
 {
   "name": "@serve.zone/nupst",
-  "version": "4.0.3",
+  "version": "4.0.4",
   "exports": "./mod.ts",
   "tasks": {
     "dev": "deno run --allow-all mod.ts",
diff --git a/install.sh b/install.sh
index a84f30b..f60b790 100644
--- a/install.sh
+++ b/install.sh
@@ -98,7 +98,11 @@ if [ ! -t 0 ] || [ ! -t 1 ]; then
     echo "Script detected it's running in a non-interactive environment without -y flag."
     echo "Attempting to find a controlling terminal for interactive prompts..."
     # Try to use a controlling terminal for user input
-    exec < /dev/tty 2>/dev/null || INTERACTIVE=0
+    if exec < /dev/tty 2>/dev/null && [ -t 0 ]; then
+      INTERACTIVE=1
+    else
+      INTERACTIVE=0
+    fi
 
     if [ $INTERACTIVE -eq 0 ]; then
       echo "ERROR: No controlling terminal available for interactive prompts."
diff --git a/test/manualdocker/00-test-fresh-v4-install.sh b/test/manualdocker/00-test-fresh-v4-install.sh
new file mode 100755
index 0000000..517caff
--- /dev/null
+++ b/test/manualdocker/00-test-fresh-v4-install.sh
@@ -0,0 +1,168 @@
+#!/bin/bash
+#
+# Test fresh v4 installation from scratch
+# Tests the most common user scenario: clean install using curl | bash
+#
+
+set -e
+
+CONTAINER_NAME="nupst-test-fresh-v4"
+
+echo "================================================"
+echo "  NUPST Fresh v4 Installation Test"
+echo "================================================"
+echo ""
+
+# Check if container already exists
+if docker ps -a --format '{{.Names}}' | grep -q "^${CONTAINER_NAME}$"; then
+  echo "⚠️  Container ${CONTAINER_NAME} already exists"
+  read -p "Remove and recreate? (y/N): " -n 1 -r
+  echo
+  if [[ $REPLY =~ ^[Yy]$ ]]; then
+    echo "→ Stopping and removing existing container..."
+    docker stop ${CONTAINER_NAME} 2>/dev/null || true
+    docker rm ${CONTAINER_NAME} 2>/dev/null || true
+  else
+    echo "Exiting. Remove manually with: docker rm -f ${CONTAINER_NAME}"
+    exit 1
+  fi
+fi
+
+echo "→ Creating Docker container with systemd..."
+docker run -d \
+  --name ${CONTAINER_NAME} \
+  --privileged \
+  --cgroupns=host \
+  -v /sys/fs/cgroup:/sys/fs/cgroup:rw \
+  ubuntu:22.04 \
+  /bin/bash -c "apt-get update && apt-get install -y systemd systemd-sysv && exec /sbin/init"
+
+echo "→ Waiting for systemd to initialize..."
+sleep 10
+
+echo "→ Waiting for dpkg lock to be released..."
+docker exec ${CONTAINER_NAME} bash -c "
+  while fuser /var/lib/dpkg/lock-frontend >/dev/null 2>&1; do
+    echo '  Waiting for dpkg lock...'
+    sleep 2
+  done
+  echo '  dpkg lock released'
+"
+
+echo "→ Installing prerequisites (curl)..."
+docker exec ${CONTAINER_NAME} bash -c "
+  apt-get update -qq
+  apt-get install -y -qq curl
+"
+
+echo ""
+echo "→ Installing NUPST v4 using curl | bash..."
+echo "   Command: curl -sSL https://code.foss.global/serve.zone/nupst/raw/branch/main/install.sh | bash -s -- -y"
+echo ""
+
+docker exec ${CONTAINER_NAME} bash -c "
+  curl -sSL https://code.foss.global/serve.zone/nupst/raw/branch/main/install.sh | bash -s -- -y
+"
+
+echo ""
+echo "================================================"
+echo "  Verifying Installation"
+echo "================================================"
+echo ""
+
+echo "→ Checking binary location..."
+docker exec ${CONTAINER_NAME} bash -c "
+  if [ -f /opt/nupst/nupst ]; then
+    echo '  ✓ Binary exists at /opt/nupst/nupst'
+    ls -lh /opt/nupst/nupst
+  else
+    echo '  ✗ Binary not found at /opt/nupst/nupst'
+    exit 1
+  fi
+"
+
+echo ""
+echo "→ Checking symlink..."
+docker exec ${CONTAINER_NAME} bash -c "
+  if [ -L /usr/local/bin/nupst ]; then
+    echo '  ✓ Symlink exists at /usr/local/bin/nupst'
+    ls -lh /usr/local/bin/nupst
+  elif [ -L /usr/bin/nupst ]; then
+    echo '  ✓ Symlink exists at /usr/bin/nupst'
+    ls -lh /usr/bin/nupst
+  else
+    echo '  ✗ Symlink not found in /usr/local/bin or /usr/bin'
+    exit 1
+  fi
+"
+
+echo ""
+echo "→ Checking PATH integration..."
+docker exec ${CONTAINER_NAME} bash -c "
+  NUPST_PATH=\$(which nupst 2>/dev/null)
+  if [ -n \"\$NUPST_PATH\" ]; then
+    echo '  ✓ nupst found in PATH at: '\$NUPST_PATH
+  else
+    echo '  ✗ nupst not found in PATH'
+    echo '  PATH contents:'
+    echo \$PATH
+    exit 1
+  fi
+"
+
+echo ""
+echo "→ Testing nupst command execution..."
+docker exec ${CONTAINER_NAME} nupst --version
+
+echo ""
+echo "→ Creating minimal config for service test..."
+docker exec ${CONTAINER_NAME} bash -c "
+  mkdir -p /etc/nupst
+  cat > /etc/nupst/config.json << 'EOF'
+{
+  \"version\": \"4.0\",
+  \"upsDevices\": [],
+  \"groups\": [],
+  \"checkInterval\": 30000
+}
+EOF
+  echo '  ✓ Minimal config created'
+"
+
+echo ""
+echo "→ Testing service creation..."
+docker exec ${CONTAINER_NAME} bash -c "
+  echo '  Running: nupst service enable'
+  nupst service enable
+
+  if [ -f /etc/systemd/system/nupst.service ]; then
+    echo '  ✓ Service file created successfully'
+  else
+    echo '  ✗ Service file creation failed'
+    exit 1
+  fi
+"
+
+echo ""
+echo "→ Checking if service is enabled..."
+docker exec ${CONTAINER_NAME} systemctl is-enabled nupst
+
+echo ""
+echo "================================================"
+echo "  ✓ Fresh v4 Installation Test Complete"
+echo "================================================"
+echo ""
+echo "Installation verified successfully:"
+echo "  • Binary installed to /opt/nupst/nupst"
+echo "  • Symlink created for global access"
+echo "  • nupst command available in PATH"
+echo "  • Command executes correctly"
+echo "  • Systemd service file created"
+echo ""
+echo "Useful commands:"
+echo "  docker exec -it ${CONTAINER_NAME} bash"
+echo "  docker exec ${CONTAINER_NAME} nupst --help"
+echo "  docker exec ${CONTAINER_NAME} nupst service status"
+echo "  docker stop ${CONTAINER_NAME}"
+echo "  docker rm -f ${CONTAINER_NAME}"
+echo ""
diff --git a/ts/migrations/migration-v3-to-v4.ts b/ts/migrations/migration-v3-to-v4.ts
index 5e59412..30b3ed5 100644
--- a/ts/migrations/migration-v3-to-v4.ts
+++ b/ts/migrations/migration-v3-to-v4.ts
@@ -4,19 +4,38 @@ import { logger } from '../logger.ts';
 /**
  * Migration from v3 (upsList) to v4 (upsDevices)
  *
- * Detects v3 format:
+ * Transforms v3 format with flat SNMP config:
  * {
- *   upsList: [ ... ],
- *   groups: [ ... ],
- *   checkInterval: 30000
+ *   upsList: [
+ *     {
+ *       id: "ups-1",
+ *       name: "UPS 1",
+ *       host: "192.168.1.1",
+ *       port: 161,
+ *       community: "public",
+ *       version: "1"  // string
+ *     }
+ *   ]
  * }
  *
- * Converts to:
+ * To v4 format with nested SNMP config:
  * {
  *   version: "4.0",
- *   upsDevices: [ ... ],  // renamed from upsList
- *   groups: [ ... ],
- *   checkInterval: 30000
+ *   upsDevices: [
+ *     {
+ *       id: "ups-1",
+ *       name: "UPS 1",
+ *       snmp: {
+ *         host: "192.168.1.1",
+ *         port: 161,
+ *         community: "public",
+ *         version: 1,  // number
+ *         timeout: 5000
+ *       },
+ *       thresholds: { battery: 60, runtime: 20 },
+ *       groups: []
+ *     }
+ *   ]
  * }
  */
 export class MigrationV3ToV4 extends BaseMigration {
@@ -30,16 +49,58 @@ export class MigrationV3ToV4 extends BaseMigration {
   }
 
   async migrate(config: any): Promise<any> {
-    logger.info(`${this.getName()}: Renaming upsList to upsDevices...`);
+    logger.info(`${this.getName()}: Migrating v3 config to v4 format...`);
+    logger.dim(`  - Renaming upsList → upsDevices`);
+    logger.dim(`  - Restructuring UPS devices (flat → nested snmp config)`);
+
+    // Transform each UPS device from v3 flat structure to v4 nested structure
+    const transformedDevices = config.upsList.map((device: any) => {
+      // Build SNMP config object
+      const snmpConfig: any = {
+        host: device.host,
+        port: device.port || 161,
+        version: typeof device.version === 'string' ? parseInt(device.version, 10) : device.version,
+        timeout: device.timeout || 5000,
+      };
+
+      // Add SNMPv1/v2c fields
+      if (device.community) {
+        snmpConfig.community = device.community;
+      }
+
+      // Add SNMPv3 fields
+      if (device.securityLevel) snmpConfig.securityLevel = device.securityLevel;
+      if (device.username) snmpConfig.username = device.username;
+      if (device.authProtocol) snmpConfig.authProtocol = device.authProtocol;
+      if (device.authKey) snmpConfig.authKey = device.authKey;
+      if (device.privProtocol) snmpConfig.privProtocol = device.privProtocol;
+      if (device.privKey) snmpConfig.privKey = device.privKey;
+
+      // Add UPS model if present
+      if (device.upsModel) snmpConfig.upsModel = device.upsModel;
+      if (device.customOIDs) snmpConfig.customOIDs = device.customOIDs;
+
+      // Return v4 format with nested structure
+      return {
+        id: device.id,
+        name: device.name,
+        snmp: snmpConfig,
+        thresholds: device.thresholds || {
+          battery: 60,
+          runtime: 20,
+        },
+        groups: device.groups || [],
+      };
+    });
 
     const migrated = {
       version: this.toVersion,
-      upsDevices: config.upsList,  // Rename upsList → upsDevices
+      upsDevices: transformedDevices,
       groups: config.groups || [],
       checkInterval: config.checkInterval || 30000,
     };
 
-    logger.success(`${this.getName()}: Migration complete`);
+    logger.success(`${this.getName()}: Migration complete (${transformedDevices.length} devices transformed)`);
     return migrated;
   }
 }