Merge pull request 'Update frontend to use unprivileged Nginx on port 8080' (#34) from development into main

Reviewed-on: #34

.env.example

@@ -1,29 +1,60 @@
-# App
+# ------------------------------
+# Application
+# ------------------------------
+# Display name used in API docs/UI.
 APP_NAME=NexaPG Monitor
+# Runtime environment: dev | staging | prod | test
 ENVIRONMENT=dev
+# Backend log level: DEBUG | INFO | WARNING | ERROR
 LOG_LEVEL=INFO
 
-# Core DB
+# ------------------------------
+# Core Database (internal metadata DB)
+# ------------------------------
+# Database that stores users, targets, metrics, query stats, and audit logs.
 DB_NAME=nexapg
 DB_USER=nexapg
 DB_PASSWORD=nexapg
+# Host port mapped to the internal PostgreSQL container port 5432.
 DB_PORT=5433
 
-# Backend
+# ------------------------------
+# Backend API
+# ------------------------------
+# Host port mapped to backend container port 8000.
 BACKEND_PORT=8000
+# JWT signing secret. Change this in every non-local environment.
 JWT_SECRET_KEY=change_this_super_secret
 JWT_ALGORITHM=HS256
+# Access token lifetime in minutes.
 JWT_ACCESS_TOKEN_MINUTES=15
+# Refresh token lifetime in minutes (10080 = 7 days).
 JWT_REFRESH_TOKEN_MINUTES=10080
-# Generate with: python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
+# Key used to encrypt monitored target passwords at rest.
+# Generate with:
+# python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
 ENCRYPTION_KEY=REPLACE_WITH_FERNET_KEY
-# Dev: set to * to allow all origins (credentials disabled automatically)
+# Allowed CORS origins for browser clients.
+# Use comma-separated values, e.g.:
+# CORS_ORIGINS=http://localhost:5173,https://nexapg.example.com
+# Dev-only shortcut:
+# CORS_ORIGINS=*
 CORS_ORIGINS=http://localhost:5173,http://localhost:8080
+# Target polling interval in seconds.
 POLL_INTERVAL_SECONDS=30
+# Active Connection Ratio alert is only evaluated when total sessions
+# are at least this number (reduces false positives on low-traffic DBs).
+ALERT_ACTIVE_CONNECTION_RATIO_MIN_TOTAL_CONNECTIONS=5
+# Rollback Ratio tuning to reduce false positives on low traffic.
+ALERT_ROLLBACK_RATIO_WINDOW_MINUTES=15
+ALERT_ROLLBACK_RATIO_MIN_TOTAL_TRANSACTIONS=100
+ALERT_ROLLBACK_RATIO_MIN_ROLLBACKS=10
+# Initial admin bootstrap user (created on first startup if not present).
 INIT_ADMIN_EMAIL=admin@example.com
 INIT_ADMIN_PASSWORD=ChangeMe123!
 
+# ------------------------------
 # Frontend
+# ------------------------------
+# Host port mapped to frontend container port 80.
 FRONTEND_PORT=5173
-# For reverse proxy + SSL prefer relative path to avoid mixed-content.
-VITE_API_URL=/api/v1

.github/workflows/docker-release.yml

@@ -0,0 +1,107 @@
+name: Docker Publish (Release)
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+    inputs:
+      version:
+        description: "Version tag to publish (e.g. 0.1.2 or v0.1.2)"
+        required: false
+        type: string
+
+jobs:
+  publish:
+    name: Build and Push Docker Images
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+      attestations: write
+
+    env:
+      # Optional repo variable. If unset, DOCKERHUB_USERNAME is used.
+      IMAGE_NAMESPACE: ${{ vars.DOCKERHUB_NAMESPACE }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Resolve version/tag
+        id: ver
+        shell: bash
+        run: |
+          RAW_TAG="${{ github.event.release.tag_name }}"
+          if [ -z "$RAW_TAG" ]; then
+            RAW_TAG="${{ inputs.version }}"
+          fi
+          if [ -z "$RAW_TAG" ]; then
+            RAW_TAG="${GITHUB_REF_NAME}"
+          fi
+
+          CLEAN_TAG="${RAW_TAG#v}"
+          echo "raw=$RAW_TAG" >> "$GITHUB_OUTPUT"
+          echo "clean=$CLEAN_TAG" >> "$GITHUB_OUTPUT"
+
+      - name: Set image namespace
+        id: ns
+        shell: bash
+        run: |
+          NS="${IMAGE_NAMESPACE}"
+          if [ -z "$NS" ]; then
+            NS="${{ secrets.DOCKERHUB_USERNAME }}"
+          fi
+          if [ -z "$NS" ]; then
+            echo "Missing Docker Hub namespace. Set repo var DOCKERHUB_NAMESPACE or secret DOCKERHUB_USERNAME."
+            exit 1
+          fi
+          echo "value=$NS" >> "$GITHUB_OUTPUT"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push backend image
+        uses: docker/build-push-action@v6
+        with:
+          context: ./backend
+          file: ./backend/Dockerfile
+          push: true
+          provenance: mode=max
+          sbom: true
+          labels: |
+            org.opencontainers.image.title=NexaPG Backend
+            org.opencontainers.image.vendor=Nesterovic IT-Services e.U.
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
+            org.opencontainers.image.version=${{ steps.ver.outputs.clean }}
+          tags: |
+            ${{ steps.ns.outputs.value }}/nexapg-backend:${{ steps.ver.outputs.clean }}
+            ${{ steps.ns.outputs.value }}/nexapg-backend:latest
+          cache-from: type=registry,ref=${{ steps.ns.outputs.value }}/nexapg-backend:buildcache
+          cache-to: type=registry,ref=${{ steps.ns.outputs.value }}/nexapg-backend:buildcache,mode=max
+
+      - name: Build and push frontend image
+        uses: docker/build-push-action@v6
+        with:
+          context: ./frontend
+          file: ./frontend/Dockerfile
+          push: true
+          provenance: mode=max
+          sbom: true
+          build-args: |
+            VITE_API_URL=/api/v1
+          labels: |
+            org.opencontainers.image.title=NexaPG Frontend
+            org.opencontainers.image.vendor=Nesterovic IT-Services e.U.
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
+            org.opencontainers.image.version=${{ steps.ver.outputs.clean }}
+          tags: |
+            ${{ steps.ns.outputs.value }}/nexapg-frontend:${{ steps.ver.outputs.clean }}
+            ${{ steps.ns.outputs.value }}/nexapg-frontend:latest
+          cache-from: type=registry,ref=${{ steps.ns.outputs.value }}/nexapg-frontend:buildcache
+          cache-to: type=registry,ref=${{ steps.ns.outputs.value }}/nexapg-frontend:buildcache,mode=max

.github/workflows/migration-safety.yml

@@ -0,0 +1,86 @@
+name: Migration Safety
+
+on:
+  push:
+    branches: ["main", "master"]
+  pull_request:
+
+jobs:
+  migration-safety:
+    name: Alembic upgrade/downgrade safety
+    runs-on: ubuntu-latest
+
+    services:
+      postgres:
+        image: postgres:16
+        env:
+          POSTGRES_DB: nexapg
+          POSTGRES_USER: nexapg
+          POSTGRES_PASSWORD: nexapg
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd "pg_isready -U nexapg -d nexapg"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 30
+
+    env:
+      DB_HOST: postgres
+      DB_PORT: 5432
+      DB_NAME: nexapg
+      DB_USER: nexapg
+      DB_PASSWORD: nexapg
+      JWT_SECRET_KEY: ci-jwt-secret-key
+      ENCRYPTION_KEY: MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDA=
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install backend dependencies
+        run: pip install -r backend/requirements.txt
+
+      - name: Install PostgreSQL client tools
+        run: sudo apt-get update && sudo apt-get install -y postgresql-client
+
+      - name: Wait for PostgreSQL
+        env:
+          PGPASSWORD: nexapg
+        run: |
+          for i in $(seq 1 60); do
+            if pg_isready -h postgres -p 5432 -U nexapg -d nexapg; then
+              exit 0
+            fi
+            sleep 2
+          done
+          echo "PostgreSQL did not become ready in time."
+          exit 1
+
+      - name: Alembic upgrade -> downgrade -1 -> upgrade
+        working-directory: backend
+        run: |
+          alembic upgrade head
+          alembic downgrade -1
+          alembic upgrade head
+
+      - name: Validate schema consistency after roundtrip
+        env:
+          PGPASSWORD: nexapg
+        run: |
+          cd backend
+          alembic upgrade head
+          pg_dump -h postgres -p 5432 -U nexapg -d nexapg --schema-only --no-owner --no-privileges \
+            | sed '/^\\restrict /d; /^\\unrestrict /d' > /tmp/schema_head_before.sql
+
+          alembic downgrade -1
+          alembic upgrade head
+          pg_dump -h postgres -p 5432 -U nexapg -d nexapg --schema-only --no-owner --no-privileges \
+            | sed '/^\\restrict /d; /^\\unrestrict /d' > /tmp/schema_head_after.sql
+
+          diff -u /tmp/schema_head_before.sql /tmp/schema_head_after.sql

.github/workflows/pg-compat-matrix.yml

@@ -0,0 +1,69 @@
+name: PostgreSQL Compatibility Matrix
+
+on:
+  push:
+    branches: ["main", "master", "development"]
+  pull_request:
+
+jobs:
+  pg-compat:
+    name: PG${{ matrix.pg_version }} smoke
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        pg_version: ["14", "15", "16", "17", "18"]
+
+    services:
+      postgres:
+        image: postgres:${{ matrix.pg_version }}
+        env:
+          POSTGRES_DB: compatdb
+          POSTGRES_USER: postgres
+          POSTGRES_PASSWORD: postgres
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd "pg_isready -U postgres -d compatdb"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 20
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install backend dependencies
+        run: pip install -r backend/requirements.txt
+
+      - name: Enable pg_stat_statements in service container
+        run: |
+          PG_CID="$(docker ps --filter "ancestor=postgres:${{ matrix.pg_version }}" --format "{{.ID}}" | head -n1)"
+          if [ -z "$PG_CID" ]; then
+            echo "Could not find postgres service container for version ${{ matrix.pg_version }}"
+            docker ps -a
+            exit 1
+          fi
+
+          echo "Using postgres container: $PG_CID"
+          docker exec "$PG_CID" psql -U postgres -d compatdb -c "ALTER SYSTEM SET shared_preload_libraries = 'pg_stat_statements';"
+          docker restart "$PG_CID"
+
+          for i in $(seq 1 40); do
+            if docker exec "$PG_CID" pg_isready -U postgres -d compatdb; then
+              break
+            fi
+            sleep 2
+          done
+
+          docker exec "$PG_CID" psql -U postgres -d compatdb -c "CREATE EXTENSION IF NOT EXISTS pg_stat_statements;"
+
+      - name: Run PostgreSQL compatibility smoke checks
+        env:
+          PG_DSN_CANDIDATES: postgresql://postgres:postgres@postgres:5432/compatdb?sslmode=disable,postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable
+        run: python backend/scripts/pg_compat_smoke.py

Makefile

@@ -1,7 +1,8 @@
 .PHONY: up down logs migrate
 
 up:
-	docker compose up -d --build
+	docker compose pull
+	docker compose up -d
 
 down:
 	docker compose down

README.md

@@ -1,113 +1,423 @@
-# NexaPG - PostgreSQL Monitoring Stack
+# NexaPG
 
-Docker-basierte Monitoring-Loesung fuer mehrere PostgreSQL-Targets mit FastAPI + React.
+<p align="center">
+  <img src="frontend/public/nexapg-logo.svg" alt="NexaPG Logo" width="180" />
+</p>
 
-## Features
+NexaPG is a full-stack PostgreSQL monitoring platform for multiple remote targets.
+It combines FastAPI, React, and PostgreSQL in a Docker Compose stack with RBAC, polling collectors, query insights, alerting, and target-owner email notifications.
 
-- Multi-target PostgreSQL Monitoring (remote)
-- Polling Collector fuer:
-  - `pg_stat_database`
-  - `pg_stat_activity`
-  - `pg_stat_bgwriter`
-  - `pg_locks`
-  - `pg_stat_statements` (falls auf Target aktiviert)
-- Core-DB fuer:
-  - User/Auth/RBAC (`admin`, `operator`, `viewer`)
-  - Targets (Credentials verschluesselt via Fernet)
-  - Metrics / Query Stats
-  - Audit Logs
-- Auth mit JWT Access/Refresh Tokens
-- FastAPI + SQLAlchemy async + Alembic
-- React (Vite) Frontend mit:
-  - Login/Logout
-  - Dashboard
-  - Target Detail mit Charts
-  - Query Insights
-  - Admin User Management
-- Health Endpoints:
-  - `/api/v1/healthz`
-  - `/api/v1/readyz`
+## Table of Contents
 
-## Struktur
+- [Quick Deploy (Prebuilt Images)](#quick-deploy-prebuilt-images)
+- [Prerequisites](#prerequisites)
+- [Make Commands](#make-commands)
+- [Configuration Reference (`.env`)](#configuration-reference-env)
+- [Core Functional Areas](#core-functional-areas)
+- [Service Information](#service-information)
+- [Target Owner Notifications](#target-owner-notifications)
+- [API Overview](#api-overview)
+- [API Error Format](#api-error-format)
+- [`pg_stat_statements` Requirement](#pg_stat_statements-requirement)
+- [Reverse Proxy / SSL Guidance](#reverse-proxy--ssl-guidance)
+- [PostgreSQL Compatibility Smoke Test](#postgresql-compatibility-smoke-test)
+- [Troubleshooting](#troubleshooting)
+- [Security Notes](#security-notes)
 
-- `backend/` FastAPI App
-- `frontend/` React (Vite) App
-- `ops/` Scripts
-- `docker-compose.yml` Stack
-- `.env.example` Konfigurationsvorlage
+## Highlights
 
-## Schnellstart
+- Multi-target monitoring for remote PostgreSQL instances
+- Optional one-click target onboarding for "all databases" discovery on an instance
+- PostgreSQL compatibility support: `14`, `15`, `16`, `17`, `18`
+- JWT auth (`access` + `refresh`) and RBAC (`admin`, `operator`, `viewer`)
+- Polling collector for metrics, locks, activity, and optional `pg_stat_statements`
+- Target detail overview (instance, storage, replication, core performance metrics)
+- Alerts system:
+  - standard built-in alerts
+  - custom SQL alerts (admin/operator)
+  - warning + alert severities
+  - real-time UI updates + toast notifications
+- Target owners: alert emails are sent only to responsible users assigned to a target
+- SMTP settings in admin UI (send-only) with test mail support
+- Structured backend logs + audit logs
 
-1. Env-Datei erstellen:
+## UI Preview
+
+### Dashboard
+
+![Dashboard Overview](docs/screenshots/dashboard-overview.png)
+
+### Targets Management
+
+![Targets Management](docs/screenshots/targets-management.png)
+
+### Query Insights
+
+![Query Insights](docs/screenshots/query-insights.png)
+
+### Alerts
+
+![Alerts](docs/screenshots/alerts.png)
+
+### Admin Settings
+
+![Admin Settings](docs/screenshots/admin-settings.png)
+
+### Target Detail (DBA Mode)
+
+![Target Detail DBA](docs/screenshots/target-detail-dba.png)
+
+### Target Detail (Easy Mode)
+
+![Target Detail Easy](docs/screenshots/target-detail-easy.png)
+
+## Repository Layout
+
+- `backend/` FastAPI app, SQLAlchemy async models, Alembic migrations, collector services
+- `frontend/` React + Vite UI
+- `ops/` helper files/scripts
+- `docker-compose.yml` full local stack
+- `.env.example` complete environment template
+- `Makefile` common commands
+
+## Prerequisites
+
+- Docker Engine `24+`
+- Docker Compose `v2+`
+- GNU Make (optional but recommended)
+- Open host ports (or custom values in `.env`):
+  - `FRONTEND_PORT` (default `5173`)
+  - `BACKEND_PORT` (default `8000`)
+  - `DB_PORT` (default `5433`)
+
+Optional:
+
+- `psql` for manual DB checks
+
+## Quick Deploy (Prebuilt Images)
+
+If you only want to run NexaPG from published Docker Hub images, use the bootstrap script:
 
 ```bash
+mkdir -p /opt/NexaPG
+cd /opt/NexaPG
+wget -O bootstrap-compose.sh https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main/ops/scripts/bootstrap-compose.sh
+chmod +x bootstrap-compose.sh
+./bootstrap-compose.sh
+```
+
+This downloads:
+
+- `docker-compose.yml`
+- `.env.example`
+- `Makefile`
+
+Then:
+
+```bash
+# generate JWT secret
+python -c "import secrets; print(secrets.token_urlsafe(64))"
+# generate Fernet encryption key
+python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
+# put both values into .env (JWT_SECRET_KEY / ENCRYPTION_KEY)
+# note: .env is auto-created by bootstrap if it does not exist
+make up
+```
+
+Manual download alternative:
+
+```bash
+mkdir -p /opt/NexaPG
+cd /opt/NexaPG
+wget https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main/docker-compose.yml
+wget https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main/.env.example
+wget https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main/Makefile
 cp .env.example .env
 ```
 
-2. Fernet Key setzen:
+`make up` pulls `nesterovicit/nexapg-backend:latest` and `nesterovicit/nexapg-frontend:latest`, then starts the stack.
+
+Open the application:
+
+- Frontend: `http://<SERVER_IP>:<FRONTEND_PORT>`
+- API base: `http://<SERVER_IP>:<BACKEND_PORT>/api/v1`
+- OpenAPI: `http://<SERVER_IP>:<BACKEND_PORT>/docs`
+
+Initial admin bootstrap user (created from `.env` if missing):
+
+- Email: value from `INIT_ADMIN_EMAIL`
+- Password: value from `INIT_ADMIN_PASSWORD`
+
+## Make Commands
 
 ```bash
-python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
+make up        # pull latest images and start all services
+make down      # stop all services
+make logs      # follow compose logs
+make migrate   # optional/manual: run alembic upgrade head in backend container
 ```
 
-Wert in `.env` bei `ENCRYPTION_KEY` eintragen.
+Note: Migrations run automatically when the backend container starts (`entrypoint.sh`).
 
-3. Stack starten:
+## Configuration Reference (`.env`)
 
-```bash
-make up
-```
+### Application
 
-4. URLs:
+| Variable | Description |
+|---|---|
+| `APP_NAME` | Application display name |
+| `ENVIRONMENT` | Runtime environment (`dev`, `staging`, `prod`, `test`) |
+| `LOG_LEVEL` | Backend log level (`DEBUG`, `INFO`, `WARNING`, `ERROR`) |
 
-- Frontend: `http://localhost:5173`
-- Backend API: `http://localhost:8000/api/v1`
-- OpenAPI: `http://localhost:8000/docs`
+### Core Database
 
-Default Admin (aus `.env`):
-- Email: `admin@example.com`
-- Passwort: `ChangeMe123!`
+| Variable | Description |
+|---|---|
+| `DB_NAME` | Core metadata database name |
+| `DB_USER` | Core database user |
+| `DB_PASSWORD` | Core database password |
+| `DB_PORT` | Host port mapped to internal PostgreSQL `5432` |
 
-## Commands
+### Backend / Security
 
-```bash
-make up
-make down
-make logs
-make migrate
-```
+| Variable | Description |
+|---|---|
+| `BACKEND_PORT` | Host port mapped to backend container port `8000` |
+| `JWT_SECRET_KEY` | JWT signing secret |
+| `JWT_ALGORITHM` | JWT algorithm (default `HS256`) |
+| `JWT_ACCESS_TOKEN_MINUTES` | Access token lifetime in minutes |
+| `JWT_REFRESH_TOKEN_MINUTES` | Refresh token lifetime in minutes |
+| `ENCRYPTION_KEY` | Fernet key for target credentials and SMTP password encryption |
+| `CORS_ORIGINS` | Allowed CORS origins (comma-separated or `*` for dev only) |
+| `POLL_INTERVAL_SECONDS` | Collector polling interval |
+| `INIT_ADMIN_EMAIL` | Bootstrap admin email |
+| `INIT_ADMIN_PASSWORD` | Bootstrap admin password |
 
-## API (Minimum)
+### Alert Noise Tuning
+
+| Variable | Description |
+|---|---|
+| `ALERT_ACTIVE_CONNECTION_RATIO_MIN_TOTAL_CONNECTIONS` | Minimum total sessions required before evaluating active-connection ratio |
+| `ALERT_ROLLBACK_RATIO_WINDOW_MINUTES` | Time window for rollback ratio evaluation |
+| `ALERT_ROLLBACK_RATIO_MIN_TOTAL_TRANSACTIONS` | Minimum transaction volume before rollback ratio is evaluated |
+| `ALERT_ROLLBACK_RATIO_MIN_ROLLBACKS` | Minimum rollback count before rollback ratio is evaluated |
+
+### Frontend
+
+| Variable | Description |
+|---|---|
+| `FRONTEND_PORT` | Host port mapped to frontend container port `80` |
+
+## Core Functional Areas
+
+### Targets
+
+- Create, list, edit, delete targets
+- Test target connection before save
+- Optional "discover all databases" mode (creates one monitored target per discovered DB)
+- Configure SSL mode per target
+- Toggle `pg_stat_statements` usage per target
+- Assign responsible users (target owners)
+
+### Target Details
+
+- Database Overview section with instance, role, uptime, size, replication, and core metrics
+- Metric charts with range selection and live mode
+- Locks and activity tables
+
+### Query Insights
+
+- Uses collected `pg_stat_statements` data
+- Ranking and categorization views
+- Search and pagination
+- Disabled automatically for targets where query insights flag is off
+
+### Alerts
+
+- Warning and alert severity split
+- Expandable alert cards with details and recommended actions
+- Custom alert definitions (SQL + thresholds)
+- Real-time refresh and in-app toast notifications
+
+### Admin Settings
+
+- User management (RBAC)
+- SMTP settings for outgoing alert mails:
+  - enable/disable
+  - host/port/auth
+  - STARTTLS / SSL mode
+  - from email + from name
+  - recipient test mail
+
+### Service Information
+
+- Sidebar entry for runtime and system details
+- Displays current version, latest known version, uptime, host, and platform
+- "Check for Updates" against the latest published release in the official upstream repository (`git.nesterovic.cc/nessi/NexaPG`)
+- Version/update source are read-only in UI (maintainer-controlled in code/release flow)
+- Local displayed version is code-defined in `backend/app/core/config.py` (`NEXAPG_VERSION`) and not configurable via `.env`
+
+## Target Owner Notifications
+
+Email alert routing is target-specific:
+
+- only users assigned as owners for a target receive that target's alert emails
+- supports multiple owners per target
+- notification sending is throttled to reduce repeated alert spam
+
+## API Overview
+
+### Health
+
+- `GET /api/v1/healthz`
+- `GET /api/v1/readyz`
+
+### Auth
 
 - `POST /api/v1/auth/login`
 - `POST /api/v1/auth/refresh`
 - `POST /api/v1/auth/logout`
 - `GET /api/v1/me`
-- CRUD: `GET/POST/PUT/DELETE /api/v1/targets`
-- `GET /api/v1/targets/{id}/metrics?from=&to=&metric=`
+
+### Targets
+
+- `GET /api/v1/targets`
+- `POST /api/v1/targets`
+- `POST /api/v1/targets/test-connection`
+- `GET /api/v1/targets/{id}`
+- `PUT /api/v1/targets/{id}`
+- `DELETE /api/v1/targets/{id}`
+- `GET /api/v1/targets/{id}/owners`
+- `PUT /api/v1/targets/{id}/owners`
+- `GET /api/v1/targets/owner-candidates`
+- `GET /api/v1/targets/{id}/metrics`
 - `GET /api/v1/targets/{id}/locks`
 - `GET /api/v1/targets/{id}/activity`
 - `GET /api/v1/targets/{id}/top-queries`
-- Admin-only CRUD users:
-  - `GET /api/v1/admin/users`
-  - `POST /api/v1/admin/users`
-  - `PUT /api/v1/admin/users/{user_id}`
-  - `DELETE /api/v1/admin/users/{user_id}`
+- `GET /api/v1/targets/{id}/overview`
 
-## Security Notes
+### Alerts
 
-- Keine Secrets hardcoded
-- Passwoerter als Argon2 Hash
-- Target-Credentials verschluesselt (Fernet)
-- CORS via Env steuerbar
-- Audit Logs fuer Login / Logout / Target- und User-Aenderungen
-- Rate limiting: Platzhalter (kann spaeter middleware-basiert ergaenzt werden)
+- `GET /api/v1/alerts/status`
+- `GET /api/v1/alerts/definitions`
+- `POST /api/v1/alerts/definitions`
+- `PUT /api/v1/alerts/definitions/{id}`
+- `DELETE /api/v1/alerts/definitions/{id}`
+- `POST /api/v1/alerts/definitions/test`
 
-## Wichtiger Hinweis zu `pg_stat_statements`
+### Admin
 
-Auf jedem monitored Target muss `pg_stat_statements` aktiviert sein, sonst bleiben Query Insights leer.
-Beispiel:
+- `GET /api/v1/admin/users`
+- `POST /api/v1/admin/users`
+- `PUT /api/v1/admin/users/{user_id}`
+- `DELETE /api/v1/admin/users/{user_id}`
+- `GET /api/v1/admin/settings/email`
+- `PUT /api/v1/admin/settings/email`
+- `POST /api/v1/admin/settings/email/test`
+
+### Service Information
+
+- `GET /api/v1/service/info`
+- `POST /api/v1/service/info/check`
+
+## API Error Format
+
+All 4xx/5xx responses use a consistent JSON payload:
+
+```json
+{
+  "code": "validation_error",
+  "message": "Request validation failed",
+  "details": [],
+  "request_id": "c8f0f888-2365-4b86-a5de-b3f0e9df4a4b"
+}
+```
+
+Common fields:
+
+- `code`: stable machine-readable error code
+- `message`: human-readable summary
+- `details`: optional extra context (validation list, debug context, etc.)
+- `request_id`: request correlation ID (also returned in `X-Request-ID` header)
+
+Common error codes:
+
+- `bad_request` (`400`)
+- `unauthorized` (`401`)
+- `forbidden` (`403`)
+- `not_found` (`404`)
+- `conflict` (`409`)
+- `validation_error` (`422`)
+- `target_unreachable` (`503`)
+- `internal_error` (`500`)
+
+## `pg_stat_statements` Requirement
+
+Query Insights requires `pg_stat_statements` on the monitored target:
 
 ```sql
 CREATE EXTENSION IF NOT EXISTS pg_stat_statements;
 ```
+
+If unavailable, disable it per target in target settings.
+
+## Reverse Proxy / SSL Guidance
+
+For production, serve frontend and API under the same public origin via reverse proxy.
+
+- Frontend URL example: `https://monitor.example.com`
+- Proxy API path `/api/` to backend service
+- Route `/api/v1` to the backend service
+
+This prevents mixed-content and CORS issues.
+
+## PostgreSQL Compatibility Smoke Test
+
+Run manually against one DSN:
+
+```bash
+PG_DSN='postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable' \
+python backend/scripts/pg_compat_smoke.py
+```
+
+Run with DSN candidates (CI style):
+
+```bash
+PG_DSN_CANDIDATES='postgresql://postgres:postgres@postgres:5432/compatdb?sslmode=disable,postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable' \
+python backend/scripts/pg_compat_smoke.py
+```
+
+## Troubleshooting
+
+### Backend container keeps restarting during `make migrate`
+
+Most common reason: failed migration. Check logs:
+
+```bash
+docker compose logs --tail=200 backend
+docker compose logs --tail=200 db
+```
+
+### CORS or mixed-content issues behind SSL proxy
+
+- Ensure proxy forwards `/api/` (or `/api/v1`) to backend
+- Set correct frontend origin(s) in `CORS_ORIGINS`
+
+### `rejected SSL upgrade` for a target
+
+Target likely does not support SSL with current settings.
+Set target `sslmode` to `disable` (or correct SSL config on target DB).
+
+### Query Insights empty
+
+- Check target has `Use pg_stat_statements` enabled
+- Verify extension exists on target (`CREATE EXTENSION ...`)
+
+## Security Notes
+
+- No secrets hardcoded in repository
+- Passwords hashed with Argon2
+- Sensitive values encrypted at rest (Fernet)
+- RBAC enforced on protected endpoints
+- Audit logs for critical actions
+- Collector error logging includes throttling to reduce repeated noise

backend/Dockerfile

@@ -1,4 +1,5 @@
-FROM python:3.12-slim AS base
+ARG PYTHON_BASE_IMAGE=python:3.13-alpine
+FROM ${PYTHON_BASE_IMAGE} AS base
 
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
@@ -6,7 +7,17 @@ ENV PIP_NO_CACHE_DIR=1
 
 WORKDIR /app
 
-RUN addgroup --system app && adduser --system --ingroup app app
+RUN if command -v apt-get >/dev/null 2>&1; then \
+      apt-get update && apt-get upgrade -y && rm -rf /var/lib/apt/lists/*; \
+    elif command -v apk >/dev/null 2>&1; then \
+      apk upgrade --no-cache; \
+    fi
+
+RUN if addgroup --help 2>&1 | grep -q -- '--system'; then \
+      addgroup --system app && adduser --system --ingroup app app; \
+    else \
+      addgroup -S app && adduser -S -G app app; \
+    fi
 
 COPY requirements.txt /app/requirements.txt
 RUN pip install --upgrade pip && pip install -r /app/requirements.txt

backend/alembic/versions/0002_alert_definitions.py

@@ -0,0 +1,43 @@
+"""add alert definitions
+
+Revision ID: 0002_alert_definitions
+Revises: 0001_init
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0002_alert_definitions"
+down_revision = "0001_init"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "alert_definitions",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(length=160), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("target_id", sa.Integer(), sa.ForeignKey("targets.id", ondelete="CASCADE"), nullable=True),
+        sa.Column("sql_text", sa.Text(), nullable=False),
+        sa.Column("comparison", sa.String(length=10), nullable=False, server_default="gte"),
+        sa.Column("warning_threshold", sa.Float(), nullable=True),
+        sa.Column("alert_threshold", sa.Float(), nullable=False),
+        sa.Column("enabled", sa.Boolean(), nullable=False, server_default=sa.text("true")),
+        sa.Column("created_by_user_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+    )
+    op.create_index("ix_alert_definitions_target_id", "alert_definitions", ["target_id"])
+    op.create_index("ix_alert_definitions_created_by_user_id", "alert_definitions", ["created_by_user_id"])
+    op.create_index("ix_alert_definitions_created_at", "alert_definitions", ["created_at"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_alert_definitions_created_at", table_name="alert_definitions")
+    op.drop_index("ix_alert_definitions_created_by_user_id", table_name="alert_definitions")
+    op.drop_index("ix_alert_definitions_target_id", table_name="alert_definitions")
+    op.drop_table("alert_definitions")

backend/alembic/versions/0003_target_pg_stat_statements_flag.py

@@ -0,0 +1,26 @@
+"""add target pg_stat_statements flag
+
+Revision ID: 0003_pg_stat_statements_flag
+Revises: 0002_alert_definitions
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0003_pg_stat_statements_flag"
+down_revision = "0002_alert_definitions"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "targets",
+        sa.Column("use_pg_stat_statements", sa.Boolean(), nullable=False, server_default=sa.text("true")),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("targets", "use_pg_stat_statements")

backend/alembic/versions/0004_email_settings.py

@@ -0,0 +1,38 @@
+"""add email notification settings
+
+Revision ID: 0004_email_settings
+Revises: 0003_pg_stat_statements_flag
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0004_email_settings"
+down_revision = "0003_pg_stat_statements_flag"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "email_notification_settings",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("enabled", sa.Boolean(), nullable=False, server_default=sa.text("false")),
+        sa.Column("smtp_host", sa.String(length=255), nullable=True),
+        sa.Column("smtp_port", sa.Integer(), nullable=False, server_default=sa.text("587")),
+        sa.Column("smtp_username", sa.String(length=255), nullable=True),
+        sa.Column("encrypted_smtp_password", sa.Text(), nullable=True),
+        sa.Column("from_email", sa.String(length=255), nullable=True),
+        sa.Column("use_starttls", sa.Boolean(), nullable=False, server_default=sa.text("true")),
+        sa.Column("use_ssl", sa.Boolean(), nullable=False, server_default=sa.text("false")),
+        sa.Column("alert_recipients", sa.JSON(), nullable=False, server_default=sa.text("'[]'::json")),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("email_notification_settings")

backend/alembic/versions/0005_target_owners_notifications.py

@@ -0,0 +1,58 @@
+"""add target owners and alert notification events
+
+Revision ID: 0005_target_owners
+Revises: 0004_email_settings
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0005_target_owners"
+down_revision = "0004_email_settings"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "target_owners",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("target_id", sa.Integer(), nullable=False),
+        sa.Column("user_id", sa.Integer(), nullable=False),
+        sa.Column("assigned_by_user_id", sa.Integer(), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.ForeignKeyConstraint(["assigned_by_user_id"], ["users.id"], ondelete="SET NULL"),
+        sa.ForeignKeyConstraint(["target_id"], ["targets.id"], ondelete="CASCADE"),
+        sa.ForeignKeyConstraint(["user_id"], ["users.id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("target_id", "user_id", name="uq_target_owner_target_user"),
+    )
+    op.create_index(op.f("ix_target_owners_target_id"), "target_owners", ["target_id"], unique=False)
+    op.create_index(op.f("ix_target_owners_user_id"), "target_owners", ["user_id"], unique=False)
+
+    op.create_table(
+        "alert_notification_events",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("alert_key", sa.String(length=200), nullable=False),
+        sa.Column("target_id", sa.Integer(), nullable=False),
+        sa.Column("severity", sa.String(length=16), nullable=False),
+        sa.Column("last_seen_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.Column("last_sent_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.ForeignKeyConstraint(["target_id"], ["targets.id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("alert_key", "target_id", "severity", name="uq_alert_notif_event_key_target_sev"),
+    )
+    op.create_index(op.f("ix_alert_notification_events_alert_key"), "alert_notification_events", ["alert_key"], unique=False)
+    op.create_index(op.f("ix_alert_notification_events_target_id"), "alert_notification_events", ["target_id"], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_alert_notification_events_target_id"), table_name="alert_notification_events")
+    op.drop_index(op.f("ix_alert_notification_events_alert_key"), table_name="alert_notification_events")
+    op.drop_table("alert_notification_events")
+
+    op.drop_index(op.f("ix_target_owners_user_id"), table_name="target_owners")
+    op.drop_index(op.f("ix_target_owners_target_id"), table_name="target_owners")
+    op.drop_table("target_owners")

backend/alembic/versions/0006_email_from_name.py

@@ -0,0 +1,23 @@
+"""add from_name to email settings
+
+Revision ID: 0006_email_from_name
+Revises: 0005_target_owners
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0006_email_from_name"
+down_revision = "0005_target_owners"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("email_notification_settings", sa.Column("from_name", sa.String(length=255), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("email_notification_settings", "from_name")

backend/alembic/versions/0007_email_templates.py

@@ -0,0 +1,31 @@
+"""email templates and drop recipients list
+
+Revision ID: 0007_email_templates
+Revises: 0006_email_from_name
+Create Date: 2026-02-12
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0007_email_templates"
+down_revision = "0006_email_from_name"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("email_notification_settings", sa.Column("warning_subject_template", sa.Text(), nullable=True))
+    op.add_column("email_notification_settings", sa.Column("alert_subject_template", sa.Text(), nullable=True))
+    op.add_column("email_notification_settings", sa.Column("warning_body_template", sa.Text(), nullable=True))
+    op.add_column("email_notification_settings", sa.Column("alert_body_template", sa.Text(), nullable=True))
+    op.drop_column("email_notification_settings", "alert_recipients")
+
+
+def downgrade() -> None:
+    op.add_column("email_notification_settings", sa.Column("alert_recipients", sa.JSON(), nullable=False, server_default="[]"))
+    op.drop_column("email_notification_settings", "alert_body_template")
+    op.drop_column("email_notification_settings", "warning_body_template")
+    op.drop_column("email_notification_settings", "alert_subject_template")
+    op.drop_column("email_notification_settings", "warning_subject_template")

backend/alembic/versions/0008_service_settings.py

@@ -0,0 +1,34 @@
+"""add service info settings
+
+Revision ID: 0008_service_settings
+Revises: 0007_email_templates
+Create Date: 2026-02-13
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0008_service_settings"
+down_revision = "0007_email_templates"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "service_info_settings",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("current_version", sa.String(length=64), nullable=False, server_default="0.1.0"),
+        sa.Column("release_check_url", sa.String(length=500), nullable=True),
+        sa.Column("latest_version", sa.String(length=64), nullable=True),
+        sa.Column("update_available", sa.Boolean(), nullable=False, server_default=sa.false()),
+        sa.Column("last_checked_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("last_check_error", sa.Text(), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.text("now()")),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.text("now()")),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("service_info_settings")

backend/alembic/versions/0009_user_profile_fields.py

@@ -0,0 +1,26 @@
+"""add user first and last name fields
+
+Revision ID: 0009_user_profile_fields
+Revises: 0008_service_settings
+Create Date: 2026-02-13
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0009_user_profile_fields"
+down_revision = "0008_service_settings"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("users", sa.Column("first_name", sa.String(length=120), nullable=True))
+    op.add_column("users", sa.Column("last_name", sa.String(length=120), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("users", "last_name")
+    op.drop_column("users", "first_name")
+

backend/app/api/router.py

@@ -1,9 +1,12 @@
 from fastapi import APIRouter
-from app.api.routes import admin_users, auth, health, me, targets
+from app.api.routes import admin_settings, admin_users, alerts, auth, health, me, service_info, targets
 
 api_router = APIRouter()
 api_router.include_router(health.router, tags=["health"])
 api_router.include_router(auth.router, prefix="/auth", tags=["auth"])
 api_router.include_router(me.router, tags=["auth"])
 api_router.include_router(targets.router, prefix="/targets", tags=["targets"])
+api_router.include_router(alerts.router, prefix="/alerts", tags=["alerts"])
+api_router.include_router(service_info.router, prefix="/service", tags=["service"])
 api_router.include_router(admin_users.router, prefix="/admin/users", tags=["admin"])
+api_router.include_router(admin_settings.router, prefix="/admin/settings", tags=["admin"])

backend/app/api/routes/admin_settings.py

@@ -0,0 +1,136 @@
+from email.message import EmailMessage
+from email.utils import formataddr
+import smtplib
+import ssl
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.core.deps import require_roles
+from app.core.errors import api_error
+from app.models.models import EmailNotificationSettings, User
+from app.schemas.admin_settings import EmailSettingsOut, EmailSettingsTestRequest, EmailSettingsUpdate
+from app.services.audit import write_audit_log
+from app.services.crypto import decrypt_secret, encrypt_secret
+
+router = APIRouter()
+
+
+async def _get_or_create_settings(db: AsyncSession) -> EmailNotificationSettings:
+    settings = await db.scalar(select(EmailNotificationSettings).limit(1))
+    if settings:
+        return settings
+    settings = EmailNotificationSettings()
+    db.add(settings)
+    await db.commit()
+    await db.refresh(settings)
+    return settings
+
+
+def _to_out(settings: EmailNotificationSettings) -> EmailSettingsOut:
+    return EmailSettingsOut(
+        enabled=settings.enabled,
+        smtp_host=settings.smtp_host,
+        smtp_port=settings.smtp_port,
+        smtp_username=settings.smtp_username,
+        from_name=settings.from_name,
+        from_email=settings.from_email,
+        use_starttls=settings.use_starttls,
+        use_ssl=settings.use_ssl,
+        warning_subject_template=settings.warning_subject_template,
+        alert_subject_template=settings.alert_subject_template,
+        warning_body_template=settings.warning_body_template,
+        alert_body_template=settings.alert_body_template,
+        has_password=bool(settings.encrypted_smtp_password),
+        updated_at=settings.updated_at,
+    )
+
+
+@router.get("/email", response_model=EmailSettingsOut)
+async def get_email_settings(
+    admin: User = Depends(require_roles("admin")),
+    db: AsyncSession = Depends(get_db),
+) -> EmailSettingsOut:
+    _ = admin
+    settings = await _get_or_create_settings(db)
+    return _to_out(settings)
+
+
+@router.put("/email", response_model=EmailSettingsOut)
+async def update_email_settings(
+    payload: EmailSettingsUpdate,
+    admin: User = Depends(require_roles("admin")),
+    db: AsyncSession = Depends(get_db),
+) -> EmailSettingsOut:
+    settings = await _get_or_create_settings(db)
+    settings.enabled = payload.enabled
+    settings.smtp_host = payload.smtp_host.strip() if payload.smtp_host else None
+    settings.smtp_port = payload.smtp_port
+    settings.smtp_username = payload.smtp_username.strip() if payload.smtp_username else None
+    settings.from_name = payload.from_name.strip() if payload.from_name else None
+    settings.from_email = str(payload.from_email) if payload.from_email else None
+    settings.use_starttls = payload.use_starttls
+    settings.use_ssl = payload.use_ssl
+    settings.warning_subject_template = payload.warning_subject_template.strip() if payload.warning_subject_template else None
+    settings.alert_subject_template = payload.alert_subject_template.strip() if payload.alert_subject_template else None
+    settings.warning_body_template = payload.warning_body_template.strip() if payload.warning_body_template else None
+    settings.alert_body_template = payload.alert_body_template.strip() if payload.alert_body_template else None
+
+    if payload.clear_smtp_password:
+        settings.encrypted_smtp_password = None
+    elif payload.smtp_password:
+        settings.encrypted_smtp_password = encrypt_secret(payload.smtp_password)
+
+    await db.commit()
+    await db.refresh(settings)
+    await write_audit_log(db, "admin.email_settings.update", admin.id, {"enabled": settings.enabled})
+    return _to_out(settings)
+
+
+@router.post("/email/test")
+async def test_email_settings(
+    payload: EmailSettingsTestRequest,
+    admin: User = Depends(require_roles("admin")),
+    db: AsyncSession = Depends(get_db),
+) -> dict:
+    settings = await _get_or_create_settings(db)
+    if not settings.smtp_host:
+        raise HTTPException(status_code=400, detail=api_error("smtp_host_missing", "SMTP host is not configured"))
+    if not settings.from_email:
+        raise HTTPException(status_code=400, detail=api_error("smtp_from_email_missing", "From email is not configured"))
+
+    password = decrypt_secret(settings.encrypted_smtp_password) if settings.encrypted_smtp_password else None
+    message = EmailMessage()
+    message["From"] = formataddr((settings.from_name, settings.from_email)) if settings.from_name else settings.from_email
+    message["To"] = str(payload.recipient)
+    message["Subject"] = payload.subject
+    message.set_content(payload.message)
+
+    try:
+        if settings.use_ssl:
+            with smtplib.SMTP_SSL(
+                settings.smtp_host,
+                settings.smtp_port,
+                timeout=10,
+                context=ssl.create_default_context(),
+            ) as smtp:
+                if settings.smtp_username:
+                    smtp.login(settings.smtp_username, password or "")
+                smtp.send_message(message)
+        else:
+            with smtplib.SMTP(settings.smtp_host, settings.smtp_port, timeout=10) as smtp:
+                if settings.use_starttls:
+                    smtp.starttls(context=ssl.create_default_context())
+                if settings.smtp_username:
+                    smtp.login(settings.smtp_username, password or "")
+                smtp.send_message(message)
+    except Exception as exc:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("smtp_test_failed", "SMTP test failed", {"error": str(exc)}),
+        ) from exc
+
+    await write_audit_log(db, "admin.email_settings.test", admin.id, {"recipient": str(payload.recipient)})
+    return {"status": "sent", "recipient": str(payload.recipient)}

backend/app/api/routes/admin_users.py

@@ -3,6 +3,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.core.db import get_db
 from app.core.deps import require_roles
+from app.core.errors import api_error
 from app.core.security import hash_password
 from app.models.models import User
 from app.schemas.user import UserCreate, UserOut, UserUpdate
@@ -22,8 +23,14 @@ async def list_users(admin: User = Depends(require_roles("admin")), db: AsyncSes
 async def create_user(payload: UserCreate, admin: User = Depends(require_roles("admin")), db: AsyncSession = Depends(get_db)) -> UserOut:
     exists = await db.scalar(select(User).where(User.email == payload.email))
     if exists:
-        raise HTTPException(status_code=409, detail="Email already exists")
-    user = User(email=payload.email, password_hash=hash_password(payload.password), role=payload.role)
+        raise HTTPException(status_code=409, detail=api_error("email_exists", "Email already exists"))
+    user = User(
+        email=payload.email,
+        first_name=payload.first_name,
+        last_name=payload.last_name,
+        password_hash=hash_password(payload.password),
+        role=payload.role,
+    )
     db.add(user)
     await db.commit()
     await db.refresh(user)
@@ -40,10 +47,17 @@ async def update_user(
 ) -> UserOut:
     user = await db.scalar(select(User).where(User.id == user_id))
     if not user:
-        raise HTTPException(status_code=404, detail="User not found")
+        raise HTTPException(status_code=404, detail=api_error("user_not_found", "User not found"))
     update_data = payload.model_dump(exclude_unset=True)
-    if "password" in update_data and update_data["password"]:
-        user.password_hash = hash_password(update_data.pop("password"))
+    next_email = update_data.get("email")
+    if next_email and next_email != user.email:
+        existing = await db.scalar(select(User).where(User.email == next_email))
+        if existing and existing.id != user.id:
+            raise HTTPException(status_code=409, detail=api_error("email_exists", "Email already exists"))
+    if "password" in update_data:
+        raw_password = update_data.pop("password")
+        if raw_password:
+            user.password_hash = hash_password(raw_password)
     for key, value in update_data.items():
         setattr(user, key, value)
     await db.commit()
@@ -55,10 +69,10 @@ async def update_user(
 @router.delete("/{user_id}")
 async def delete_user(user_id: int, admin: User = Depends(require_roles("admin")), db: AsyncSession = Depends(get_db)) -> dict:
     if user_id == admin.id:
-        raise HTTPException(status_code=400, detail="Cannot delete yourself")
+        raise HTTPException(status_code=400, detail=api_error("cannot_delete_self", "Cannot delete yourself"))
     user = await db.scalar(select(User).where(User.id == user_id))
     if not user:
-        raise HTTPException(status_code=404, detail="User not found")
+        raise HTTPException(status_code=404, detail=api_error("user_not_found", "User not found"))
     await db.delete(user)
     await db.commit()
     await write_audit_log(db, "admin.user.delete", admin.id, {"deleted_user_id": user_id})

backend/app/api/routes/alerts.py

@@ -0,0 +1,157 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.core.deps import get_current_user, require_roles
+from app.core.errors import api_error
+from app.models.models import AlertDefinition, Target, User
+from app.schemas.alert import (
+    AlertDefinitionCreate,
+    AlertDefinitionOut,
+    AlertDefinitionTestRequest,
+    AlertDefinitionTestResponse,
+    AlertDefinitionUpdate,
+    AlertStatusResponse,
+    StandardAlertReferenceItem,
+)
+from app.services.alerts import (
+    get_standard_alert_reference,
+    get_alert_status,
+    invalidate_alert_cache,
+    run_scalar_sql_for_target,
+    validate_alert_sql,
+    validate_alert_thresholds,
+)
+from app.services.alert_notifications import process_target_owner_notifications
+from app.services.audit import write_audit_log
+
+router = APIRouter()
+
+
+async def _validate_target_exists(db: AsyncSession, target_id: int | None) -> None:
+    if target_id is None:
+        return
+    target_exists = await db.scalar(select(Target.id).where(Target.id == target_id))
+    if target_exists is None:
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+
+
+@router.get("/status", response_model=AlertStatusResponse)
+async def list_alert_status(
+    user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)
+) -> AlertStatusResponse:
+    _ = user
+    payload = await get_alert_status(db, use_cache=True)
+    await process_target_owner_notifications(db, payload)
+    return payload
+
+
+@router.get("/standard-reference", response_model=list[StandardAlertReferenceItem])
+async def list_standard_alert_reference(
+    user: User = Depends(get_current_user),
+) -> list[StandardAlertReferenceItem]:
+    _ = user
+    return [StandardAlertReferenceItem(**item) for item in get_standard_alert_reference()]
+
+
+@router.get("/definitions", response_model=list[AlertDefinitionOut])
+async def list_alert_definitions(
+    user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)
+) -> list[AlertDefinitionOut]:
+    _ = user
+    defs = (await db.scalars(select(AlertDefinition).order_by(AlertDefinition.id.desc()))).all()
+    return [AlertDefinitionOut.model_validate(item) for item in defs]
+
+
+@router.post("/definitions", response_model=AlertDefinitionOut, status_code=status.HTTP_201_CREATED)
+async def create_alert_definition(
+    payload: AlertDefinitionCreate,
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> AlertDefinitionOut:
+    await _validate_target_exists(db, payload.target_id)
+    sql_text = validate_alert_sql(payload.sql_text)
+    validate_alert_thresholds(payload.comparison, payload.warning_threshold, payload.alert_threshold)
+
+    definition = AlertDefinition(
+        name=payload.name,
+        description=payload.description,
+        target_id=payload.target_id,
+        sql_text=sql_text,
+        comparison=payload.comparison,
+        warning_threshold=payload.warning_threshold,
+        alert_threshold=payload.alert_threshold,
+        enabled=payload.enabled,
+        created_by_user_id=user.id,
+    )
+    db.add(definition)
+    await db.commit()
+    await db.refresh(definition)
+    invalidate_alert_cache()
+    await write_audit_log(db, "alert.definition.create", user.id, {"alert_definition_id": definition.id, "name": definition.name})
+    return AlertDefinitionOut.model_validate(definition)
+
+
+@router.put("/definitions/{definition_id}", response_model=AlertDefinitionOut)
+async def update_alert_definition(
+    definition_id: int,
+    payload: AlertDefinitionUpdate,
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> AlertDefinitionOut:
+    definition = await db.scalar(select(AlertDefinition).where(AlertDefinition.id == definition_id))
+    if definition is None:
+        raise HTTPException(status_code=404, detail=api_error("alert_definition_not_found", "Alert definition not found"))
+
+    updates = payload.model_dump(exclude_unset=True)
+    if "target_id" in updates:
+        await _validate_target_exists(db, updates["target_id"])
+    if "sql_text" in updates and updates["sql_text"] is not None:
+        updates["sql_text"] = validate_alert_sql(updates["sql_text"])
+
+    comparison = updates.get("comparison", definition.comparison)
+    warning_threshold = updates.get("warning_threshold", definition.warning_threshold)
+    alert_threshold = updates.get("alert_threshold", definition.alert_threshold)
+    validate_alert_thresholds(comparison, warning_threshold, alert_threshold)
+
+    for key, value in updates.items():
+        setattr(definition, key, value)
+    await db.commit()
+    await db.refresh(definition)
+    invalidate_alert_cache()
+    await write_audit_log(db, "alert.definition.update", user.id, {"alert_definition_id": definition.id})
+    return AlertDefinitionOut.model_validate(definition)
+
+
+@router.delete("/definitions/{definition_id}")
+async def delete_alert_definition(
+    definition_id: int,
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> dict:
+    definition = await db.scalar(select(AlertDefinition).where(AlertDefinition.id == definition_id))
+    if definition is None:
+        raise HTTPException(status_code=404, detail=api_error("alert_definition_not_found", "Alert definition not found"))
+    await db.delete(definition)
+    await db.commit()
+    invalidate_alert_cache()
+    await write_audit_log(db, "alert.definition.delete", user.id, {"alert_definition_id": definition_id})
+    return {"status": "deleted"}
+
+
+@router.post("/definitions/test", response_model=AlertDefinitionTestResponse)
+async def test_alert_definition(
+    payload: AlertDefinitionTestRequest,
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> AlertDefinitionTestResponse:
+    _ = user
+    target = await db.scalar(select(Target).where(Target.id == payload.target_id))
+    if target is None:
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    try:
+        value = await run_scalar_sql_for_target(target, payload.sql_text)
+        return AlertDefinitionTestResponse(ok=True, value=value)
+    except Exception as exc:
+        return AlertDefinitionTestResponse(ok=False, error=str(exc))

backend/app/api/routes/auth.py

@@ -1,10 +1,11 @@
 from fastapi import APIRouter, Depends, HTTPException, status
-from jose import JWTError, jwt
+import jwt
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.core.config import get_settings
 from app.core.db import get_db
 from app.core.deps import get_current_user
+from app.core.errors import api_error
 from app.core.security import create_access_token, create_refresh_token, verify_password
 from app.models.models import User
 from app.schemas.auth import LoginRequest, RefreshRequest, TokenResponse
@@ -19,7 +20,10 @@ settings = get_settings()
 async def login(payload: LoginRequest, db: AsyncSession = Depends(get_db)) -> TokenResponse:
     user = await db.scalar(select(User).where(User.email == payload.email))
     if not user or not verify_password(payload.password, user.password_hash):
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid credentials")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("invalid_credentials", "Invalid credentials"),
+        )
 
     await write_audit_log(db, action="auth.login", user_id=user.id, payload={"email": user.email})
     return TokenResponse(access_token=create_access_token(str(user.id)), refresh_token=create_refresh_token(str(user.id)))
@@ -29,15 +33,24 @@ async def login(payload: LoginRequest, db: AsyncSession = Depends(get_db)) -> To
 async def refresh(payload: RefreshRequest, db: AsyncSession = Depends(get_db)) -> TokenResponse:
     try:
         token_payload = jwt.decode(payload.refresh_token, settings.jwt_secret_key, algorithms=[settings.jwt_algorithm])
-    except JWTError as exc:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid refresh token") from exc
+    except jwt.InvalidTokenError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("invalid_refresh_token", "Invalid refresh token"),
+        ) from exc
 
     if token_payload.get("type") != "refresh":
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid refresh token type")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("invalid_refresh_token_type", "Invalid refresh token type"),
+        )
     user_id = token_payload.get("sub")
     user = await db.scalar(select(User).where(User.id == int(user_id)))
     if not user:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("user_not_found", "User not found"),
+        )
 
     await write_audit_log(db, action="auth.refresh", user_id=user.id, payload={})
     return TokenResponse(access_token=create_access_token(str(user.id)), refresh_token=create_refresh_token(str(user.id)))

backend/app/api/routes/me.py

@@ -1,7 +1,12 @@
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.ext.asyncio import AsyncSession
+from app.core.db import get_db
 from app.core.deps import get_current_user
+from app.core.errors import api_error
+from app.core.security import hash_password, verify_password
 from app.models.models import User
-from app.schemas.user import UserOut
+from app.schemas.user import UserOut, UserPasswordChange
+from app.services.audit import write_audit_log
 
 router = APIRouter()
 
@@ -9,3 +14,27 @@ router = APIRouter()
 @router.get("/me", response_model=UserOut)
 async def me(user: User = Depends(get_current_user)) -> UserOut:
     return UserOut.model_validate(user)
+
+
+@router.post("/me/password")
+async def change_password(
+    payload: UserPasswordChange,
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+) -> dict:
+    if not verify_password(payload.current_password, user.password_hash):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=api_error("invalid_current_password", "Current password is incorrect"),
+        )
+
+    if verify_password(payload.new_password, user.password_hash):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=api_error("password_reuse_not_allowed", "New password must be different"),
+        )
+
+    user.password_hash = hash_password(payload.new_password)
+    await db.commit()
+    await write_audit_log(db, action="auth.password_change", user_id=user.id, payload={})
+    return {"status": "ok"}

backend/app/api/routes/service_info.py

@@ -0,0 +1,94 @@
+import os
+import platform
+from datetime import datetime, timezone
+
+from fastapi import APIRouter, Depends
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import get_settings
+from app.core.db import get_db
+from app.core.deps import get_current_user
+from app.models.models import ServiceInfoSettings, User
+from app.schemas.service_info import ServiceInfoCheckResult, ServiceInfoOut
+from app.services.service_info import (
+    UPSTREAM_REPO_WEB,
+    fetch_latest_from_upstream,
+    is_update_available,
+    utcnow,
+)
+
+router = APIRouter()
+settings = get_settings()
+service_started_at = datetime.now(timezone.utc)
+
+
+async def _get_or_create_service_settings(db: AsyncSession) -> ServiceInfoSettings:
+    row = await db.scalar(select(ServiceInfoSettings).limit(1))
+    if row:
+        return row
+    row = ServiceInfoSettings(current_version=settings.app_version)
+    db.add(row)
+    await db.commit()
+    await db.refresh(row)
+    return row
+
+
+def _to_out(row: ServiceInfoSettings) -> ServiceInfoOut:
+    uptime_seconds = int((utcnow() - service_started_at).total_seconds())
+    return ServiceInfoOut(
+        app_name=settings.app_name,
+        environment=settings.environment,
+        api_prefix=settings.api_v1_prefix,
+        app_version=settings.app_version,
+        hostname=platform.node() or os.getenv("HOSTNAME", "unknown"),
+        python_version=platform.python_version(),
+        platform=platform.platform(),
+        service_started_at=service_started_at,
+        uptime_seconds=max(uptime_seconds, 0),
+        update_source=UPSTREAM_REPO_WEB,
+        latest_version=row.latest_version,
+        latest_ref=(row.release_check_url or None),
+        update_available=row.update_available,
+        last_checked_at=row.last_checked_at,
+        last_check_error=row.last_check_error,
+    )
+
+
+@router.get("/info", response_model=ServiceInfoOut)
+async def get_service_info(
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+) -> ServiceInfoOut:
+    _ = user
+    row = await _get_or_create_service_settings(db)
+    return _to_out(row)
+
+
+@router.post("/info/check", response_model=ServiceInfoCheckResult)
+async def check_service_version(
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+) -> ServiceInfoCheckResult:
+    _ = user
+    row = await _get_or_create_service_settings(db)
+    check_time = utcnow()
+    latest, latest_ref, error = await fetch_latest_from_upstream()
+
+    row.last_checked_at = check_time
+    row.last_check_error = error
+    if latest:
+        row.latest_version = latest
+        row.release_check_url = latest_ref
+        row.update_available = is_update_available(settings.app_version, latest)
+    else:
+        row.update_available = False
+    await db.commit()
+    await db.refresh(row)
+    return ServiceInfoCheckResult(
+        latest_version=row.latest_version,
+        latest_ref=(row.release_check_url or None),
+        update_available=row.update_available,
+        last_checked_at=row.last_checked_at or check_time,
+        last_check_error=row.last_check_error,
+    )

backend/app/api/routes/targets.py

@@ -1,14 +1,25 @@
 from datetime import datetime
+from uuid import uuid4
+
 import asyncpg
 from fastapi import APIRouter, Depends, HTTPException, Query, status
-from sqlalchemy import and_, desc, select
+from sqlalchemy import and_, delete, desc, select
 from sqlalchemy.ext.asyncio import AsyncSession
+
 from app.core.db import get_db
 from app.core.deps import get_current_user, require_roles
-from app.models.models import Metric, QueryStat, Target, User
+from app.core.errors import api_error
+from app.models.models import Metric, QueryStat, Target, TargetOwner, User
 from app.schemas.metric import MetricOut, QueryStatOut
 from app.schemas.overview import DatabaseOverviewOut
-from app.schemas.target import TargetCreate, TargetOut, TargetUpdate
+from app.schemas.target import (
+    TargetConnectionTestRequest,
+    TargetCreate,
+    TargetOut,
+    TargetOwnerOut,
+    TargetOwnersUpdate,
+    TargetUpdate,
+)
 from app.services.audit import write_audit_log
 from app.services.collector import build_target_dsn
 from app.services.crypto import encrypt_secret
@@ -17,10 +28,120 @@ from app.services.overview_service import get_target_overview
 router = APIRouter()
 
 
+async def _owners_by_target_ids(db: AsyncSession, target_ids: list[int]) -> dict[int, list[int]]:
+    if not target_ids:
+        return {}
+    rows = (
+        await db.execute(select(TargetOwner.target_id, TargetOwner.user_id).where(TargetOwner.target_id.in_(target_ids)))
+    ).all()
+    mapping: dict[int, list[int]] = {target_id: [] for target_id in target_ids}
+    for target_id, user_id in rows:
+        mapping.setdefault(target_id, []).append(user_id)
+    return mapping
+
+
+def _target_out_with_owners(target: Target, owner_user_ids: list[int]) -> TargetOut:
+    return TargetOut(
+        id=target.id,
+        name=target.name,
+        host=target.host,
+        port=target.port,
+        dbname=target.dbname,
+        username=target.username,
+        sslmode=target.sslmode,
+        use_pg_stat_statements=target.use_pg_stat_statements,
+        owner_user_ids=owner_user_ids,
+        tags=target.tags or {},
+        created_at=target.created_at,
+    )
+
+
+async def _set_target_owners(db: AsyncSession, target_id: int, user_ids: list[int], assigned_by_user_id: int | None) -> None:
+    await db.execute(delete(TargetOwner).where(TargetOwner.target_id == target_id))
+    for user_id in sorted(set(user_ids)):
+        db.add(TargetOwner(target_id=target_id, user_id=user_id, assigned_by_user_id=assigned_by_user_id))
+
+
+async def _discover_databases(payload: TargetCreate) -> list[str]:
+    ssl = False if payload.sslmode == "disable" else True
+    conn = None
+    try:
+        conn = await asyncpg.connect(
+            host=payload.host,
+            port=payload.port,
+            database=payload.dbname,
+            user=payload.username,
+            password=payload.password,
+            ssl=ssl,
+            timeout=8,
+        )
+        rows = await conn.fetch(
+            """
+            SELECT datname
+            FROM pg_database
+            WHERE datallowconn
+              AND NOT datistemplate
+            ORDER BY datname
+            """
+        )
+        return [row["datname"] for row in rows if row["datname"]]
+    except Exception as exc:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("database_discovery_failed", "Database discovery failed", {"error": str(exc)}),
+        )
+    finally:
+        if conn:
+            await conn.close()
+
+
+async def _next_unique_target_name(db: AsyncSession, base_name: str) -> str:
+    candidate = base_name.strip()
+    suffix = 2
+    while True:
+        exists = await db.scalar(select(Target.id).where(Target.name == candidate))
+        if exists is None:
+            return candidate
+        candidate = f"{base_name} ({suffix})"
+        suffix += 1
+
+
 @router.get("", response_model=list[TargetOut])
 async def list_targets(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)) -> list[TargetOut]:
+    _ = user
     targets = (await db.scalars(select(Target).order_by(Target.id.desc()))).all()
-    return [TargetOut.model_validate(item) for item in targets]
+    owner_map = await _owners_by_target_ids(db, [item.id for item in targets])
+    return [_target_out_with_owners(item, owner_map.get(item.id, [])) for item in targets]
+
+
+@router.post("/test-connection")
+async def test_target_connection(
+    payload: TargetConnectionTestRequest,
+    user: User = Depends(require_roles("admin", "operator")),
+) -> dict:
+    _ = user
+    ssl = False if payload.sslmode == "disable" else True
+    conn = None
+    try:
+        conn = await asyncpg.connect(
+            host=payload.host,
+            port=payload.port,
+            database=payload.dbname,
+            user=payload.username,
+            password=payload.password,
+            ssl=ssl,
+            timeout=8,
+        )
+        version = await conn.fetchval("SHOW server_version")
+        return {"ok": True, "message": "Connection successful", "server_version": version}
+    except Exception as exc:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("connection_test_failed", "Connection test failed", {"error": str(exc)}),
+        )
+    finally:
+        if conn:
+            await conn.close()
 
 
 @router.post("", response_model=TargetOut, status_code=status.HTTP_201_CREATED)
@@ -29,29 +150,122 @@ async def create_target(
     user: User = Depends(require_roles("admin", "operator")),
     db: AsyncSession = Depends(get_db),
 ) -> TargetOut:
+    owner_ids = sorted(set(payload.owner_user_ids or []))
+    if owner_ids:
+        owners_exist = (await db.scalars(select(User.id).where(User.id.in_(owner_ids)))).all()
+        if len(set(owners_exist)) != len(owner_ids):
+            raise HTTPException(
+                status_code=400,
+                detail=api_error("owner_users_not_found", "One or more owner users were not found"),
+            )
+
+    encrypted_password = encrypt_secret(payload.password)
+    created_targets: list[Target] = []
+
+    if payload.discover_all_databases:
+        databases = await _discover_databases(payload)
+        if not databases:
+            raise HTTPException(
+                status_code=400,
+                detail=api_error("no_databases_discovered", "No databases discovered on target"),
+            )
+        group_id = str(uuid4())
+        base_tags = payload.tags or {}
+        for dbname in databases:
+            duplicate = await db.scalar(
+                select(Target.id).where(
+                    Target.host == payload.host,
+                    Target.port == payload.port,
+                    Target.dbname == dbname,
+                    Target.username == payload.username,
+                )
+            )
+            if duplicate is not None:
+                continue
+            target_name = await _next_unique_target_name(db, f"{payload.name} / {dbname}")
+            tags = {
+                **base_tags,
+                "monitor_mode": "all_databases",
+                "monitor_group_id": group_id,
+                "monitor_group_name": payload.name,
+            }
             target = Target(
-        name=payload.name,
+                name=target_name,
+                host=payload.host,
+                port=payload.port,
+                dbname=dbname,
+                username=payload.username,
+                encrypted_password=encrypted_password,
+                sslmode=payload.sslmode,
+                use_pg_stat_statements=payload.use_pg_stat_statements,
+                tags=tags,
+            )
+            db.add(target)
+            await db.flush()
+            created_targets.append(target)
+            if owner_ids:
+                await _set_target_owners(db, target.id, owner_ids, user.id)
+
+        if not created_targets:
+            raise HTTPException(
+                status_code=400,
+                detail=api_error("all_discovered_databases_exist", "All discovered databases already exist as targets"),
+            )
+        await db.commit()
+        for item in created_targets:
+            await db.refresh(item)
+        await write_audit_log(
+            db,
+            "target.create.all_databases",
+            user.id,
+            {"base_name": payload.name, "created_count": len(created_targets), "host": payload.host, "port": payload.port},
+        )
+        owner_map = await _owners_by_target_ids(db, [created_targets[0].id])
+        return _target_out_with_owners(created_targets[0], owner_map.get(created_targets[0].id, []))
+
+    target_name = await _next_unique_target_name(db, payload.name)
+    target = Target(
+        name=target_name,
         host=payload.host,
         port=payload.port,
         dbname=payload.dbname,
         username=payload.username,
-        encrypted_password=encrypt_secret(payload.password),
+        encrypted_password=encrypted_password,
         sslmode=payload.sslmode,
+        use_pg_stat_statements=payload.use_pg_stat_statements,
         tags=payload.tags,
     )
     db.add(target)
     await db.commit()
     await db.refresh(target)
+
+    if owner_ids:
+        await _set_target_owners(db, target.id, owner_ids, user.id)
+        await db.commit()
+
     await write_audit_log(db, "target.create", user.id, {"target_id": target.id, "name": target.name})
-    return TargetOut.model_validate(target)
+    owner_map = await _owners_by_target_ids(db, [target.id])
+    return _target_out_with_owners(target, owner_map.get(target.id, []))
+
+
+@router.get("/owner-candidates", response_model=list[TargetOwnerOut])
+async def list_owner_candidates(
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> list[TargetOwnerOut]:
+    _ = user
+    users = (await db.scalars(select(User).order_by(User.email.asc()))).all()
+    return [TargetOwnerOut(user_id=item.id, email=item.email, role=item.role) for item in users]
 
 
 @router.get("/{target_id}", response_model=TargetOut)
 async def get_target(target_id: int, user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)) -> TargetOut:
+    _ = user
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
-    return TargetOut.model_validate(target)
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    owner_map = await _owners_by_target_ids(db, [target.id])
+    return _target_out_with_owners(target, owner_map.get(target.id, []))
 
 
 @router.put("/{target_id}", response_model=TargetOut)
@@ -63,17 +277,82 @@ async def update_target(
 ) -> TargetOut:
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
 
     updates = payload.model_dump(exclude_unset=True)
+    owner_user_ids = updates.pop("owner_user_ids", None)
     if "password" in updates:
         target.encrypted_password = encrypt_secret(updates.pop("password"))
     for key, value in updates.items():
         setattr(target, key, value)
+
+    if owner_user_ids is not None:
+        owners_exist = (await db.scalars(select(User.id).where(User.id.in_(owner_user_ids)))).all()
+        if len(set(owners_exist)) != len(set(owner_user_ids)):
+            raise HTTPException(
+                status_code=400,
+                detail=api_error("owner_users_not_found", "One or more owner users were not found"),
+            )
+        await _set_target_owners(db, target.id, owner_user_ids, user.id)
+
     await db.commit()
     await db.refresh(target)
     await write_audit_log(db, "target.update", user.id, {"target_id": target.id})
-    return TargetOut.model_validate(target)
+    owner_map = await _owners_by_target_ids(db, [target.id])
+    return _target_out_with_owners(target, owner_map.get(target.id, []))
+
+
+@router.put("/{target_id}/owners", response_model=list[TargetOwnerOut])
+async def set_target_owners(
+    target_id: int,
+    payload: TargetOwnersUpdate,
+    user: User = Depends(require_roles("admin", "operator")),
+    db: AsyncSession = Depends(get_db),
+) -> list[TargetOwnerOut]:
+    target = await db.scalar(select(Target).where(Target.id == target_id))
+    if not target:
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    owner_user_ids = sorted(set(payload.user_ids))
+    if owner_user_ids:
+        owners_exist = (await db.scalars(select(User.id).where(User.id.in_(owner_user_ids)))).all()
+        if len(set(owners_exist)) != len(set(owner_user_ids)):
+            raise HTTPException(
+                status_code=400,
+                detail=api_error("owner_users_not_found", "One or more owner users were not found"),
+            )
+    await _set_target_owners(db, target_id, owner_user_ids, user.id)
+    await db.commit()
+    await write_audit_log(db, "target.owners.update", user.id, {"target_id": target_id, "owner_user_ids": owner_user_ids})
+    rows = (
+        await db.execute(
+            select(User.id, User.email, User.role)
+            .join(TargetOwner, TargetOwner.user_id == User.id)
+            .where(TargetOwner.target_id == target_id)
+            .order_by(User.email.asc())
+        )
+    ).all()
+    return [TargetOwnerOut(user_id=row.id, email=row.email, role=row.role) for row in rows]
+
+
+@router.get("/{target_id}/owners", response_model=list[TargetOwnerOut])
+async def get_target_owners(
+    target_id: int,
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+) -> list[TargetOwnerOut]:
+    _ = user
+    target = await db.scalar(select(Target).where(Target.id == target_id))
+    if not target:
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    rows = (
+        await db.execute(
+            select(User.id, User.email, User.role)
+            .join(TargetOwner, TargetOwner.user_id == User.id)
+            .where(TargetOwner.target_id == target_id)
+            .order_by(User.email.asc())
+        )
+    ).all()
+    return [TargetOwnerOut(user_id=row.id, email=row.email, role=row.role) for row in rows]
 
 
 @router.delete("/{target_id}")
@@ -84,7 +363,7 @@ async def delete_target(
 ) -> dict:
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
     await db.delete(target)
     await db.commit()
     await write_audit_log(db, "target.delete", user.id, {"target_id": target_id})
@@ -112,7 +391,22 @@ async def get_metrics(
 
 
 async def _live_conn(target: Target) -> asyncpg.Connection:
+    try:
         return await asyncpg.connect(dsn=build_target_dsn(target))
+    except (OSError, asyncpg.PostgresError) as exc:
+        raise HTTPException(
+            status_code=503,
+            detail=api_error(
+                "target_unreachable",
+                "Target database is not reachable",
+                {
+                    "target_id": target.id,
+                    "host": target.host,
+                    "port": target.port,
+                    "error": str(exc),
+                },
+            ),
+        ) from exc
 
 
 @router.get("/{target_id}/locks")
@@ -120,7 +414,7 @@ async def get_locks(target_id: int, user: User = Depends(get_current_user), db:
     _ = user
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
     conn = await _live_conn(target)
     try:
         rows = await conn.fetch(
@@ -141,7 +435,7 @@ async def get_activity(target_id: int, user: User = Depends(get_current_user), d
     _ = user
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
     conn = await _live_conn(target)
     try:
         rows = await conn.fetch(
@@ -161,6 +455,11 @@ async def get_activity(target_id: int, user: User = Depends(get_current_user), d
 @router.get("/{target_id}/top-queries", response_model=list[QueryStatOut])
 async def get_top_queries(target_id: int, user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)) -> list[QueryStatOut]:
     _ = user
+    target = await db.scalar(select(Target).where(Target.id == target_id))
+    if not target:
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    if not target.use_pg_stat_statements:
+        return []
     rows = (
         await db.scalars(
             select(QueryStat)
@@ -188,5 +487,20 @@ async def get_overview(target_id: int, user: User = Depends(get_current_user), d
     _ = user
     target = await db.scalar(select(Target).where(Target.id == target_id))
     if not target:
-        raise HTTPException(status_code=404, detail="Target not found")
+        raise HTTPException(status_code=404, detail=api_error("target_not_found", "Target not found"))
+    try:
         return await get_target_overview(target)
+    except (OSError, asyncpg.PostgresError) as exc:
+        raise HTTPException(
+            status_code=503,
+            detail=api_error(
+                "target_unreachable",
+                "Target database is not reachable",
+                {
+                    "target_id": target.id,
+                    "host": target.host,
+                    "port": target.port,
+                    "error": str(exc),
+                },
+            ),
+        ) from exc

backend/app/core/config.py

@@ -2,6 +2,8 @@ from functools import lru_cache
 from pydantic import field_validator
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
+NEXAPG_VERSION = "0.2.2"
+
 
 class Settings(BaseSettings):
     model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
@@ -25,9 +27,17 @@ class Settings(BaseSettings):
     encryption_key: str
     cors_origins: str = "http://localhost:5173"
     poll_interval_seconds: int = 30
+    alert_active_connection_ratio_min_total_connections: int = 5
+    alert_rollback_ratio_window_minutes: int = 15
+    alert_rollback_ratio_min_total_transactions: int = 100
+    alert_rollback_ratio_min_rollbacks: int = 10
     init_admin_email: str = "admin@example.com"
     init_admin_password: str = "ChangeMe123!"
 
+    @property
+    def app_version(self) -> str:
+        return NEXAPG_VERSION
+
     @property
     def database_url(self) -> str:
         return (

backend/app/core/deps.py

@@ -1,10 +1,11 @@
 from fastapi import Depends, HTTPException, status
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
-from jose import JWTError, jwt
+import jwt
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.core.config import get_settings
 from app.core.db import get_db
+from app.core.errors import api_error
 from app.models.models import User
 
 settings = get_settings()
@@ -16,27 +17,42 @@ async def get_current_user(
     db: AsyncSession = Depends(get_db),
 ) -> User:
     if not credentials:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Missing token")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("missing_token", "Missing token"),
+        )
     token = credentials.credentials
     try:
         payload = jwt.decode(token, settings.jwt_secret_key, algorithms=[settings.jwt_algorithm])
-    except JWTError as exc:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token") from exc
+    except jwt.InvalidTokenError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("invalid_token", "Invalid token"),
+        ) from exc
 
     if payload.get("type") != "access":
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token type")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("invalid_token_type", "Invalid token type"),
+        )
 
     user_id = payload.get("sub")
     user = await db.scalar(select(User).where(User.id == int(user_id)))
     if not user:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail=api_error("user_not_found", "User not found"),
+        )
     return user
 
 
 def require_roles(*roles: str):
     async def role_dependency(user: User = Depends(get_current_user)) -> User:
         if user.role not in roles:
-            raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Forbidden")
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail=api_error("forbidden", "Forbidden"),
+            )
         return user
 
     return role_dependency

backend/app/core/errors.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+from typing import Any
+
+
+def error_payload(code: str, message: str, details: Any, request_id: str) -> dict[str, Any]:
+    return {
+        "code": code,
+        "message": message,
+        "details": details,
+        "request_id": request_id,
+    }
+
+
+def api_error(code: str, message: str, details: Any = None) -> dict[str, Any]:
+    return {
+        "code": code,
+        "message": message,
+        "details": details,
+    }
+
+
+def http_status_to_code(status_code: int) -> str:
+    mapping = {
+        400: "bad_request",
+        401: "unauthorized",
+        403: "forbidden",
+        404: "not_found",
+        405: "method_not_allowed",
+        409: "conflict",
+        422: "validation_error",
+        429: "rate_limited",
+        500: "internal_error",
+        502: "bad_gateway",
+        503: "service_unavailable",
+        504: "gateway_timeout",
+    }
+    return mapping.get(status_code, f"http_{status_code}")

backend/app/core/security.py

@@ -1,5 +1,5 @@
 from datetime import datetime, timedelta, timezone
-from jose import jwt
+import jwt
 from passlib.context import CryptContext
 from app.core.config import get_settings
 

backend/app/main.py

@@ -1,12 +1,17 @@
 import asyncio
 import logging
+from uuid import uuid4
 from contextlib import asynccontextmanager
-from fastapi import FastAPI
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import JSONResponse
+from starlette.exceptions import HTTPException as StarletteHTTPException
 from sqlalchemy import select
 from app.api.router import api_router
 from app.core.config import get_settings
 from app.core.db import SessionLocal
+from app.core.errors import error_payload, http_status_to_code
 from app.core.logging import configure_logging
 from app.core.security import hash_password
 from app.models.models import User
@@ -57,4 +62,67 @@ app.add_middleware(
     allow_methods=["*"],
     allow_headers=["*"],
 )
+
+
+@app.middleware("http")
+async def request_id_middleware(request: Request, call_next):
+    request_id = request.headers.get("x-request-id") or str(uuid4())
+    request.state.request_id = request_id
+    response = await call_next(request)
+    response.headers["X-Request-ID"] = request_id
+    return response
+
+
+@app.exception_handler(HTTPException)
+@app.exception_handler(StarletteHTTPException)
+async def http_exception_handler(request: Request, exc: HTTPException | StarletteHTTPException):
+    request_id = getattr(request.state, "request_id", str(uuid4()))
+    code = http_status_to_code(exc.status_code)
+    message = "Request failed"
+    details = None
+
+    if isinstance(exc.detail, str):
+        message = exc.detail
+    elif isinstance(exc.detail, dict):
+        code = str(exc.detail.get("code", code))
+        message = str(exc.detail.get("message", message))
+        details = exc.detail.get("details")
+    elif isinstance(exc.detail, list):
+        message = "Request validation failed"
+        details = exc.detail
+
+    return JSONResponse(
+        status_code=exc.status_code,
+        content=error_payload(code=code, message=message, details=details, request_id=request_id),
+    )
+
+
+@app.exception_handler(RequestValidationError)
+async def request_validation_exception_handler(request: Request, exc: RequestValidationError):
+    request_id = getattr(request.state, "request_id", str(uuid4()))
+    return JSONResponse(
+        status_code=422,
+        content=error_payload(
+            code="validation_error",
+            message="Request validation failed",
+            details=exc.errors(),
+            request_id=request_id,
+        ),
+    )
+
+
+@app.exception_handler(Exception)
+async def unhandled_exception_handler(request: Request, exc: Exception):
+    request_id = getattr(request.state, "request_id", str(uuid4()))
+    logger.exception("unhandled_exception request_id=%s", request_id, exc_info=exc)
+    return JSONResponse(
+        status_code=500,
+        content=error_payload(
+            code="internal_error",
+            message="Internal server error",
+            details=None,
+            request_id=request_id,
+        ),
+    )
+
 app.include_router(api_router, prefix=settings.api_v1_prefix)

backend/app/models/__init__.py

@@ -1,3 +1,25 @@
-from app.models.models import AuditLog, Metric, QueryStat, Target, User
+from app.models.models import (
+    AlertDefinition,
+    AlertNotificationEvent,
+    AuditLog,
+    EmailNotificationSettings,
+    Metric,
+    QueryStat,
+    ServiceInfoSettings,
+    Target,
+    TargetOwner,
+    User,
+)
 
-__all__ = ["User", "Target", "Metric", "QueryStat", "AuditLog"]
+__all__ = [
+    "User",
+    "Target",
+    "Metric",
+    "QueryStat",
+    "ServiceInfoSettings",
+    "AuditLog",
+    "AlertDefinition",
+    "EmailNotificationSettings",
+    "TargetOwner",
+    "AlertNotificationEvent",
+]

backend/app/models/models.py

@@ -1,5 +1,5 @@
 from datetime import datetime
-from sqlalchemy import JSON, DateTime, Float, ForeignKey, Integer, String, Text, func
+from sqlalchemy import JSON, Boolean, DateTime, Float, ForeignKey, Integer, String, Text, UniqueConstraint, func
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 from app.core.db import Base
 
@@ -9,11 +9,18 @@ class User(Base):
 
     id: Mapped[int] = mapped_column(Integer, primary_key=True)
     email: Mapped[str] = mapped_column(String(255), unique=True, index=True, nullable=False)
+    first_name: Mapped[str | None] = mapped_column(String(120), nullable=True)
+    last_name: Mapped[str | None] = mapped_column(String(120), nullable=True)
     password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
     role: Mapped[str] = mapped_column(String(20), nullable=False, default="viewer")
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
 
     audit_logs: Mapped[list["AuditLog"]] = relationship(back_populates="user")
+    owned_targets: Mapped[list["TargetOwner"]] = relationship(
+        back_populates="user",
+        cascade="all, delete-orphan",
+        foreign_keys="TargetOwner.user_id",
+    )
 
 
 class Target(Base):
@@ -27,11 +34,28 @@ class Target(Base):
     username: Mapped[str] = mapped_column(String(120), nullable=False)
     encrypted_password: Mapped[str] = mapped_column(Text, nullable=False)
     sslmode: Mapped[str] = mapped_column(String(20), nullable=False, default="prefer")
+    use_pg_stat_statements: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
     tags: Mapped[dict] = mapped_column(JSON, nullable=False, default=dict)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
 
     metrics: Mapped[list["Metric"]] = relationship(back_populates="target", cascade="all, delete-orphan")
     query_stats: Mapped[list["QueryStat"]] = relationship(back_populates="target", cascade="all, delete-orphan")
+    alert_definitions: Mapped[list["AlertDefinition"]] = relationship(back_populates="target", cascade="all, delete-orphan")
+    owners: Mapped[list["TargetOwner"]] = relationship(back_populates="target", cascade="all, delete-orphan")
+
+
+class TargetOwner(Base):
+    __tablename__ = "target_owners"
+    __table_args__ = (UniqueConstraint("target_id", "user_id", name="uq_target_owner_target_user"),)
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    target_id: Mapped[int] = mapped_column(ForeignKey("targets.id", ondelete="CASCADE"), nullable=False, index=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    assigned_by_user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+
+    target: Mapped[Target] = relationship(back_populates="owners")
+    user: Mapped[User] = relationship(foreign_keys=[user_id], back_populates="owned_targets")
 
 
 class Metric(Base):
@@ -73,3 +97,84 @@ class AuditLog(Base):
     payload: Mapped[dict] = mapped_column(JSON, nullable=False, default=dict)
 
     user: Mapped[User | None] = relationship(back_populates="audit_logs")
+
+
+class AlertDefinition(Base):
+    __tablename__ = "alert_definitions"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    name: Mapped[str] = mapped_column(String(160), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    target_id: Mapped[int | None] = mapped_column(ForeignKey("targets.id", ondelete="CASCADE"), nullable=True, index=True)
+    sql_text: Mapped[str] = mapped_column(Text, nullable=False)
+    comparison: Mapped[str] = mapped_column(String(10), nullable=False, default="gte")
+    warning_threshold: Mapped[float | None] = mapped_column(Float, nullable=True)
+    alert_threshold: Mapped[float] = mapped_column(Float, nullable=False)
+    enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    created_by_user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True, index=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now(), index=True)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        server_default=func.now(),
+        onupdate=func.now(),
+    )
+
+    target: Mapped[Target | None] = relationship(back_populates="alert_definitions")
+
+
+class EmailNotificationSettings(Base):
+    __tablename__ = "email_notification_settings"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    smtp_host: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    smtp_port: Mapped[int] = mapped_column(Integer, nullable=False, default=587)
+    smtp_username: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    encrypted_smtp_password: Mapped[str | None] = mapped_column(Text, nullable=True)
+    from_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    from_email: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    use_starttls: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    use_ssl: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    warning_subject_template: Mapped[str | None] = mapped_column(Text, nullable=True)
+    alert_subject_template: Mapped[str | None] = mapped_column(Text, nullable=True)
+    warning_body_template: Mapped[str | None] = mapped_column(Text, nullable=True)
+    alert_body_template: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        server_default=func.now(),
+        onupdate=func.now(),
+    )
+
+
+class ServiceInfoSettings(Base):
+    __tablename__ = "service_info_settings"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    current_version: Mapped[str] = mapped_column(String(64), nullable=False, default="0.1.0")
+    release_check_url: Mapped[str | None] = mapped_column(String(500), nullable=True)
+    latest_version: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    update_available: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    last_checked_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    last_check_error: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        server_default=func.now(),
+        onupdate=func.now(),
+    )
+
+
+class AlertNotificationEvent(Base):
+    __tablename__ = "alert_notification_events"
+    __table_args__ = (UniqueConstraint("alert_key", "target_id", "severity", name="uq_alert_notif_event_key_target_sev"),)
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    alert_key: Mapped[str] = mapped_column(String(200), nullable=False, index=True)
+    target_id: Mapped[int] = mapped_column(ForeignKey("targets.id", ondelete="CASCADE"), nullable=False, index=True)
+    severity: Mapped[str] = mapped_column(String(16), nullable=False)
+    last_seen_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    last_sent_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())

backend/app/schemas/admin_settings.py

@@ -0,0 +1,56 @@
+from datetime import datetime
+
+from pydantic import BaseModel, EmailStr, field_validator, model_validator
+
+
+class EmailSettingsOut(BaseModel):
+    enabled: bool
+    smtp_host: str | None
+    smtp_port: int
+    smtp_username: str | None
+    from_name: str | None
+    from_email: EmailStr | None
+    use_starttls: bool
+    use_ssl: bool
+    warning_subject_template: str | None
+    alert_subject_template: str | None
+    warning_body_template: str | None
+    alert_body_template: str | None
+    has_password: bool
+    updated_at: datetime | None
+
+
+class EmailSettingsUpdate(BaseModel):
+    enabled: bool = False
+    smtp_host: str | None = None
+    smtp_port: int = 587
+    smtp_username: str | None = None
+    smtp_password: str | None = None
+    clear_smtp_password: bool = False
+    from_name: str | None = None
+    from_email: EmailStr | None = None
+    use_starttls: bool = True
+    use_ssl: bool = False
+    warning_subject_template: str | None = None
+    alert_subject_template: str | None = None
+    warning_body_template: str | None = None
+    alert_body_template: str | None = None
+
+    @field_validator("smtp_port")
+    @classmethod
+    def validate_port(cls, value: int) -> int:
+        if value < 1 or value > 65535:
+            raise ValueError("smtp_port must be between 1 and 65535")
+        return value
+
+    @model_validator(mode="after")
+    def validate_tls_combo(self):
+        if self.use_starttls and self.use_ssl:
+            raise ValueError("use_starttls and use_ssl cannot both be true")
+        return self
+
+
+class EmailSettingsTestRequest(BaseModel):
+    recipient: EmailStr
+    subject: str = "NexaPG test notification"
+    message: str = "This is a test alert notification from NexaPG."

backend/app/schemas/alert.py

@@ -0,0 +1,83 @@
+from datetime import datetime
+from pydantic import BaseModel, Field
+
+
+class AlertDefinitionBase(BaseModel):
+    name: str = Field(min_length=2, max_length=160)
+    description: str | None = None
+    target_id: int | None = None
+    sql_text: str = Field(min_length=8, max_length=4000)
+    comparison: str = "gte"
+    warning_threshold: float | None = None
+    alert_threshold: float
+    enabled: bool = True
+
+
+class AlertDefinitionCreate(AlertDefinitionBase):
+    pass
+
+
+class AlertDefinitionUpdate(BaseModel):
+    name: str | None = Field(default=None, min_length=2, max_length=160)
+    description: str | None = None
+    target_id: int | None = None
+    sql_text: str | None = Field(default=None, min_length=8, max_length=4000)
+    comparison: str | None = None
+    warning_threshold: float | None = None
+    alert_threshold: float | None = None
+    enabled: bool | None = None
+
+
+class AlertDefinitionOut(AlertDefinitionBase):
+    id: int
+    created_by_user_id: int | None = None
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = {"from_attributes": True}
+
+
+class AlertDefinitionTestRequest(BaseModel):
+    target_id: int
+    sql_text: str = Field(min_length=8, max_length=4000)
+
+
+class AlertDefinitionTestResponse(BaseModel):
+    ok: bool
+    value: float | None = None
+    error: str | None = None
+
+
+class AlertStatusItem(BaseModel):
+    alert_key: str
+    source: str
+    severity: str
+    category: str
+    name: str
+    description: str
+    target_id: int
+    target_name: str
+    value: float | None = None
+    warning_threshold: float | None = None
+    alert_threshold: float | None = None
+    comparison: str = "gte"
+    message: str
+    checked_at: datetime
+    sql_text: str | None = None
+
+
+class AlertStatusResponse(BaseModel):
+    generated_at: datetime
+    warnings: list[AlertStatusItem]
+    alerts: list[AlertStatusItem]
+    warning_count: int
+    alert_count: int
+
+
+class StandardAlertReferenceItem(BaseModel):
+    key: str
+    name: str
+    checks: str
+    comparison: str
+    warning: str
+    alert: str

backend/app/schemas/service_info.py

@@ -0,0 +1,29 @@
+from datetime import datetime
+
+from pydantic import BaseModel
+
+
+class ServiceInfoOut(BaseModel):
+    app_name: str
+    environment: str
+    api_prefix: str
+    app_version: str
+    hostname: str
+    python_version: str
+    platform: str
+    service_started_at: datetime
+    uptime_seconds: int
+    update_source: str
+    latest_version: str | None
+    latest_ref: str | None
+    update_available: bool
+    last_checked_at: datetime | None
+    last_check_error: str | None
+
+
+class ServiceInfoCheckResult(BaseModel):
+    latest_version: str | None
+    latest_ref: str | None
+    update_available: bool
+    last_checked_at: datetime
+    last_check_error: str | None

backend/app/schemas/target.py

@@ -9,11 +9,23 @@ class TargetBase(BaseModel):
     dbname: str
     username: str
     sslmode: str = "prefer"
+    use_pg_stat_statements: bool = True
+    owner_user_ids: list[int] = Field(default_factory=list)
     tags: dict = Field(default_factory=dict)
 
 
 class TargetCreate(TargetBase):
     password: str
+    discover_all_databases: bool = False
+
+
+class TargetConnectionTestRequest(BaseModel):
+    host: str
+    port: int = 5432
+    dbname: str
+    username: str
+    password: str
+    sslmode: str = "prefer"
 
 
 class TargetUpdate(BaseModel):
@@ -24,6 +36,8 @@ class TargetUpdate(BaseModel):
     username: str | None = None
     password: str | None = None
     sslmode: str | None = None
+    use_pg_stat_statements: bool | None = None
+    owner_user_ids: list[int] | None = None
     tags: dict | None = None
 
 
@@ -32,3 +46,13 @@ class TargetOut(TargetBase):
     created_at: datetime
 
     model_config = {"from_attributes": True}
+
+
+class TargetOwnerOut(BaseModel):
+    user_id: int
+    email: str
+    role: str
+
+
+class TargetOwnersUpdate(BaseModel):
+    user_ids: list[int] = Field(default_factory=list)

backend/app/schemas/user.py

@@ -1,10 +1,12 @@
 from datetime import datetime
-from pydantic import BaseModel, EmailStr
+from pydantic import BaseModel, EmailStr, field_validator
 
 
 class UserOut(BaseModel):
     id: int
     email: EmailStr
+    first_name: str | None = None
+    last_name: str | None = None
     role: str
     created_at: datetime
 
@@ -13,11 +15,27 @@ class UserOut(BaseModel):
 
 class UserCreate(BaseModel):
     email: EmailStr
+    first_name: str | None = None
+    last_name: str | None = None
     password: str
     role: str = "viewer"
 
 
 class UserUpdate(BaseModel):
     email: EmailStr | None = None
+    first_name: str | None = None
+    last_name: str | None = None
     password: str | None = None
     role: str | None = None
+
+
+class UserPasswordChange(BaseModel):
+    current_password: str
+    new_password: str
+
+    @field_validator("new_password")
+    @classmethod
+    def validate_new_password(cls, value: str) -> str:
+        if len(value) < 8:
+            raise ValueError("new_password must be at least 8 characters")
+        return value

backend/app/services/alert_notifications.py

@@ -0,0 +1,196 @@
+from __future__ import annotations
+
+import asyncio
+from datetime import datetime, timedelta, timezone
+from email.message import EmailMessage
+from email.utils import formataddr
+import smtplib
+import ssl
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.models import AlertNotificationEvent, EmailNotificationSettings, TargetOwner, User
+from app.schemas.alert import AlertStatusResponse
+from app.services.crypto import decrypt_secret
+
+_NOTIFICATION_COOLDOWN = timedelta(minutes=30)
+
+
+async def _smtp_send(
+    host: str,
+    port: int,
+    username: str | None,
+    password: str | None,
+    from_name: str | None,
+    from_email: str,
+    recipient: str,
+    subject: str,
+    body: str,
+    use_starttls: bool,
+    use_ssl: bool,
+) -> None:
+    def _send() -> None:
+        message = EmailMessage()
+        message["From"] = formataddr((from_name, from_email)) if from_name else from_email
+        message["To"] = recipient
+        message["Subject"] = subject
+        message.set_content(body)
+
+        if use_ssl:
+            with smtplib.SMTP_SSL(host, port, timeout=10, context=ssl.create_default_context()) as smtp:
+                if username:
+                    smtp.login(username, password or "")
+                smtp.send_message(message)
+            return
+        with smtplib.SMTP(host, port, timeout=10) as smtp:
+            if use_starttls:
+                smtp.starttls(context=ssl.create_default_context())
+            if username:
+                smtp.login(username, password or "")
+            smtp.send_message(message)
+
+    await asyncio.to_thread(_send)
+
+
+def _render_subject(item) -> str:
+    sev = item.severity.upper()
+    return f"[NexaPG][{sev}] {item.target_name} - {item.name}"
+
+
+def _render_body(item) -> str:
+    lines = [
+        f"Severity: {item.severity}",
+        f"Target: {item.target_name} (id={item.target_id})",
+        f"Alert: {item.name}",
+        f"Category: {item.category}",
+        f"Checked At: {item.checked_at.isoformat()}",
+        "",
+        f"Description: {item.description}",
+        f"Message: {item.message}",
+    ]
+    if item.value is not None:
+        lines.append(f"Current Value: {item.value}")
+    if item.warning_threshold is not None:
+        lines.append(f"Warning Threshold: {item.warning_threshold}")
+    if item.alert_threshold is not None:
+        lines.append(f"Alert Threshold: {item.alert_threshold}")
+    lines.append("")
+    lines.append(f"Alert Key: {item.alert_key}")
+    lines.append("Sent by NexaPG notification service.")
+    return "\n".join(lines)
+
+
+def _template_context(item) -> dict[str, str]:
+    return {
+        "severity": str(item.severity),
+        "target_name": str(item.target_name),
+        "target_id": str(item.target_id),
+        "alert_name": str(item.name),
+        "category": str(item.category),
+        "description": str(item.description),
+        "message": str(item.message),
+        "value": "" if item.value is None else str(item.value),
+        "warning_threshold": "" if item.warning_threshold is None else str(item.warning_threshold),
+        "alert_threshold": "" if item.alert_threshold is None else str(item.alert_threshold),
+        "checked_at": item.checked_at.isoformat() if item.checked_at else "",
+        "alert_key": str(item.alert_key),
+    }
+
+
+def _safe_format(template: str | None, context: dict[str, str], fallback: str) -> str:
+    if not template:
+        return fallback
+    rendered = template
+    for key, value in context.items():
+        rendered = rendered.replace("{" + key + "}", value)
+    return rendered
+
+
+async def process_target_owner_notifications(db: AsyncSession, status: AlertStatusResponse) -> None:
+    settings = await db.scalar(select(EmailNotificationSettings).limit(1))
+    if not settings or not settings.enabled:
+        return
+    if not settings.smtp_host or not settings.from_email:
+        return
+
+    password = decrypt_secret(settings.encrypted_smtp_password) if settings.encrypted_smtp_password else None
+    now = datetime.now(timezone.utc)
+    active_items = status.alerts + status.warnings
+    if not active_items:
+        return
+
+    target_ids = sorted({item.target_id for item in active_items})
+    owner_rows = (
+        await db.execute(
+            select(TargetOwner.target_id, User.email)
+            .join(User, User.id == TargetOwner.user_id)
+            .where(TargetOwner.target_id.in_(target_ids))
+        )
+    ).all()
+    owners_map: dict[int, set[str]] = {}
+    for target_id, email in owner_rows:
+        owners_map.setdefault(target_id, set()).add(email)
+
+    existing_rows = (
+        await db.scalars(
+            select(AlertNotificationEvent).where(
+                AlertNotificationEvent.target_id.in_(target_ids)
+            )
+        )
+    ).all()
+    event_map = {(row.alert_key, row.target_id, row.severity): row for row in existing_rows}
+
+    for item in active_items:
+        recipients = sorted(owners_map.get(item.target_id, set()))
+        if not recipients:
+            continue
+
+        key = (item.alert_key, item.target_id, item.severity)
+        existing = event_map.get(key)
+        should_send = existing is None or (now - existing.last_sent_at) >= _NOTIFICATION_COOLDOWN
+
+        if should_send:
+            fallback_subject = _render_subject(item)
+            fallback_body = _render_body(item)
+            context = _template_context(item)
+            if item.severity == "alert":
+                subject = _safe_format(settings.alert_subject_template, context, fallback_subject)
+                body = _safe_format(settings.alert_body_template, context, fallback_body)
+            else:
+                subject = _safe_format(settings.warning_subject_template, context, fallback_subject)
+                body = _safe_format(settings.warning_body_template, context, fallback_body)
+            for recipient in recipients:
+                try:
+                    await _smtp_send(
+                        host=settings.smtp_host,
+                        port=settings.smtp_port,
+                        username=settings.smtp_username,
+                        password=password,
+                        from_name=settings.from_name,
+                        from_email=settings.from_email,
+                        recipient=recipient,
+                        subject=subject,
+                        body=body,
+                        use_starttls=settings.use_starttls,
+                        use_ssl=settings.use_ssl,
+                    )
+                except Exception:
+                    continue
+
+        if existing:
+            existing.last_seen_at = now
+            if should_send:
+                existing.last_sent_at = now
+        else:
+            db.add(
+                AlertNotificationEvent(
+                    alert_key=item.alert_key,
+                    target_id=item.target_id,
+                    severity=item.severity,
+                    last_seen_at=now,
+                    last_sent_at=now if should_send else now,
+                )
+            )
+
+    await db.commit()

backend/app/services/alerts.py

@@ -0,0 +1,625 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import datetime, timedelta, timezone
+import re
+import time
+
+import asyncpg
+from fastapi import HTTPException
+from sqlalchemy import desc, func, select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import get_settings
+from app.core.errors import api_error
+from app.models.models import AlertDefinition, Metric, QueryStat, Target
+from app.schemas.alert import AlertStatusItem, AlertStatusResponse
+from app.services.collector import build_target_dsn
+
+settings = get_settings()
+_ALLOWED_COMPARISONS = {"gte", "gt", "lte", "lt"}
+_FORBIDDEN_SQL_WORDS = re.compile(
+    r"\b(insert|update|delete|alter|drop|truncate|create|grant|revoke|vacuum|analyze|copy|call|do)\b",
+    re.IGNORECASE,
+)
+_STATUS_CACHE_TTL_SECONDS = 15
+_status_cache: dict = {"expires": 0.0, "data": None}
+
+
+@dataclass
+class _RuleInput:
+    key: str
+    name: str
+    description: str
+    category: str
+    value: float | None
+    warning_threshold: float | None
+    alert_threshold: float | None
+    comparison: str = "gte"
+
+
+def invalidate_alert_cache() -> None:
+    _status_cache["expires"] = 0.0
+    _status_cache["data"] = None
+
+
+def get_standard_alert_reference() -> list[dict[str, str]]:
+    return [
+        {
+            "key": "target_reachability",
+            "name": "Target Reachability",
+            "checks": "Connection to target database can be established.",
+            "comparison": "-",
+            "warning": "-",
+            "alert": "On connection failure",
+        },
+        {
+            "key": "connectivity_rtt_ms",
+            "name": "Connectivity Latency",
+            "checks": "Connection handshake duration (milliseconds).",
+            "comparison": "gte",
+            "warning": "1000 ms",
+            "alert": "2500 ms",
+        },
+        {
+            "key": "collector_freshness_seconds",
+            "name": "Collector Freshness",
+            "checks": "Age of newest metric sample.",
+            "comparison": "gte",
+            "warning": f"{settings.poll_interval_seconds * 2} s (poll interval x2)",
+            "alert": f"{settings.poll_interval_seconds * 4} s (poll interval x4)",
+        },
+        {
+            "key": "active_connections_ratio",
+            "name": "Active Connection Ratio",
+            "checks": (
+                "active_connections / total_connections "
+                f"(evaluated only when total sessions >= {settings.alert_active_connection_ratio_min_total_connections})."
+            ),
+            "comparison": "gte",
+            "warning": "0.70",
+            "alert": "0.90",
+        },
+        {
+            "key": "cache_hit_ratio_low",
+            "name": "Cache Hit Ratio",
+            "checks": "Buffer cache efficiency (lower is worse).",
+            "comparison": "lte",
+            "warning": "0.95",
+            "alert": "0.90",
+        },
+        {
+            "key": "locks_total",
+            "name": "Lock Pressure",
+            "checks": "Current total lock count.",
+            "comparison": "gte",
+            "warning": "50",
+            "alert": "100",
+        },
+        {
+            "key": "checkpoints_req_15m",
+            "name": "Checkpoint Pressure (15m)",
+            "checks": "Increase of requested checkpoints in last 15 minutes.",
+            "comparison": "gte",
+            "warning": "5",
+            "alert": "15",
+        },
+        {
+            "key": "rollback_ratio",
+            "name": "Rollback Ratio",
+            "checks": (
+                f"rollback / (commit + rollback) in last {settings.alert_rollback_ratio_window_minutes} minutes "
+                f"(evaluated only when >= {settings.alert_rollback_ratio_min_total_transactions} transactions "
+                f"and >= {settings.alert_rollback_ratio_min_rollbacks} rollbacks)."
+            ),
+            "comparison": "gte",
+            "warning": "0.10",
+            "alert": "0.25",
+        },
+        {
+            "key": "deadlocks_60m",
+            "name": "Deadlocks (60m)",
+            "checks": "Increase in deadlocks during last 60 minutes.",
+            "comparison": "gte",
+            "warning": "1",
+            "alert": "5",
+        },
+        {
+            "key": "slowest_query_mean_ms",
+            "name": "Slowest Query Mean Time",
+            "checks": "Highest query mean execution time in latest snapshot.",
+            "comparison": "gte",
+            "warning": "300 ms",
+            "alert": "1000 ms",
+        },
+        {
+            "key": "slowest_query_total_ms",
+            "name": "Slowest Query Total Time",
+            "checks": "Highest query total execution time in latest snapshot.",
+            "comparison": "gte",
+            "warning": "3000 ms",
+            "alert": "10000 ms",
+        },
+    ]
+
+
+def validate_alert_thresholds(comparison: str, warning_threshold: float | None, alert_threshold: float) -> None:
+    if comparison not in _ALLOWED_COMPARISONS:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error(
+                "invalid_comparison",
+                f"Invalid comparison. Use one of {sorted(_ALLOWED_COMPARISONS)}",
+            ),
+        )
+    if warning_threshold is None:
+        return
+
+    if comparison in {"gte", "gt"} and warning_threshold > alert_threshold:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("invalid_thresholds", "For gte/gt, warning_threshold must be <= alert_threshold"),
+        )
+    if comparison in {"lte", "lt"} and warning_threshold < alert_threshold:
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("invalid_thresholds", "For lte/lt, warning_threshold must be >= alert_threshold"),
+        )
+
+
+def validate_alert_sql(sql_text: str) -> str:
+    sql = sql_text.strip().rstrip(";")
+    lowered = sql.lower().strip()
+    if not lowered.startswith("select"):
+        raise HTTPException(status_code=400, detail=api_error("invalid_alert_sql", "Alert SQL must start with SELECT"))
+    if _FORBIDDEN_SQL_WORDS.search(lowered):
+        raise HTTPException(
+            status_code=400,
+            detail=api_error("invalid_alert_sql", "Only read-only SELECT statements are allowed"),
+        )
+    if ";" in sql:
+        raise HTTPException(status_code=400, detail=api_error("invalid_alert_sql", "Only a single SQL statement is allowed"))
+    return sql
+
+
+async def _connect_target(target: Target, timeout_seconds: int = 5) -> asyncpg.Connection:
+    return await asyncpg.connect(dsn=build_target_dsn(target), timeout=timeout_seconds)
+
+
+async def run_scalar_sql_for_target(target: Target, sql_text: str) -> float:
+    sql = validate_alert_sql(sql_text)
+    conn: asyncpg.Connection | None = None
+    try:
+        conn = await _connect_target(target, timeout_seconds=6)
+        row = await conn.fetchrow(sql)
+        if not row:
+            raise ValueError("Query returned no rows")
+        value = row[0]
+        return float(value)
+    finally:
+        if conn:
+            await conn.close()
+
+
+def _compare(value: float, threshold: float, comparison: str) -> bool:
+    if comparison == "gte":
+        return value >= threshold
+    if comparison == "gt":
+        return value > threshold
+    if comparison == "lte":
+        return value <= threshold
+    if comparison == "lt":
+        return value < threshold
+    return False
+
+
+def _severity_from_thresholds(
+    value: float | None, comparison: str, warning_threshold: float | None, alert_threshold: float | None
+) -> str:
+    if value is None or alert_threshold is None:
+        return "unknown"
+    if _compare(value, alert_threshold, comparison):
+        return "alert"
+    if warning_threshold is not None and _compare(value, warning_threshold, comparison):
+        return "warning"
+    return "ok"
+
+
+def _status_message(value: float | None, comparison: str, warning_threshold: float | None, alert_threshold: float | None) -> str:
+    if value is None:
+        return "No numeric value available"
+    if alert_threshold is None:
+        return f"Current value: {value:.2f}"
+    if warning_threshold is None:
+        return f"Current value: {value:.2f} (alert when value {comparison} {alert_threshold:.2f})"
+    return (
+        f"Current value: {value:.2f} "
+        f"(warning when value {comparison} {warning_threshold:.2f}, alert when value {comparison} {alert_threshold:.2f})"
+    )
+
+
+async def _latest_metric_value(db: AsyncSession, target_id: int, metric_name: str) -> float | None:
+    row = await db.scalar(
+        select(Metric.value)
+        .where(Metric.target_id == target_id, Metric.metric_name == metric_name)
+        .order_by(desc(Metric.ts))
+        .limit(1)
+    )
+    return float(row) if row is not None else None
+
+
+async def _metric_delta(db: AsyncSession, target_id: int, metric_name: str, minutes: int) -> float | None:
+    cutoff = datetime.now(timezone.utc) - timedelta(minutes=minutes)
+    latest = await db.scalar(
+        select(Metric.value)
+        .where(Metric.target_id == target_id, Metric.metric_name == metric_name)
+        .order_by(desc(Metric.ts))
+        .limit(1)
+    )
+    oldest = await db.scalar(
+        select(Metric.value)
+        .where(Metric.target_id == target_id, Metric.metric_name == metric_name, Metric.ts >= cutoff)
+        .order_by(Metric.ts.asc())
+        .limit(1)
+    )
+    if latest is None or oldest is None:
+        return None
+    return max(0.0, float(latest) - float(oldest))
+
+
+async def _rollback_ratio_recent(
+    db: AsyncSession, target_id: int, minutes: int, min_total_transactions: int, min_rollbacks: int
+) -> tuple[float | None, float, float]:
+    commit_delta = await _metric_delta(db, target_id, "xact_commit", minutes=minutes)
+    rollback_delta = await _metric_delta(db, target_id, "xact_rollback", minutes=minutes)
+    if commit_delta is None or rollback_delta is None:
+        return None, 0.0, 0.0
+    tx_total = commit_delta + rollback_delta
+    if tx_total < float(min_total_transactions):
+        # Too little traffic in window, ratio would be noisy and misleading.
+        return None, tx_total, rollback_delta
+    if rollback_delta < float(min_rollbacks):
+        # Ignore tiny rollback counts even if ratio appears high on low absolute numbers.
+        return None, tx_total, rollback_delta
+    return (rollback_delta / tx_total) if tx_total > 0 else None, tx_total, rollback_delta
+
+
+async def _latest_query_snapshot_max(db: AsyncSession, target_id: int, column_name: str) -> float | None:
+    latest_ts = await db.scalar(select(func.max(QueryStat.ts)).where(QueryStat.target_id == target_id))
+    if latest_ts is None:
+        return None
+    column = QueryStat.mean_time if column_name == "mean_time" else QueryStat.total_time
+    value = await db.scalar(
+        select(func.max(column)).where(QueryStat.target_id == target_id, QueryStat.ts == latest_ts)
+    )
+    return float(value) if value is not None else None
+
+
+async def _build_standard_rules(db: AsyncSession, target: Target) -> tuple[list[_RuleInput], list[AlertStatusItem]]:
+    rules: list[_RuleInput] = []
+    forced_items: list[AlertStatusItem] = []
+    checked_at = datetime.now(timezone.utc)
+
+    # 1) Connectivity with RTT threshold.
+    start = time.perf_counter()
+    conn: asyncpg.Connection | None = None
+    try:
+        conn = await _connect_target(target, timeout_seconds=4)
+        await conn.fetchval("SELECT 1")
+        connect_ms = (time.perf_counter() - start) * 1000
+        rules.append(
+            _RuleInput(
+                key="connectivity_rtt_ms",
+                name="Connectivity Latency",
+                description="Checks whether the target is reachable and how long the connection handshake takes.",
+                category="availability",
+                value=connect_ms,
+                warning_threshold=1000,
+                alert_threshold=2500,
+                comparison="gte",
+            )
+        )
+    except Exception as exc:
+        forced_items.append(
+            AlertStatusItem(
+                alert_key=f"std-connectivity-down-{target.id}",
+                source="standard",
+                severity="alert",
+                category="availability",
+                name="Target Reachability",
+                description="Verifies that the monitored database can be reached by the collector.",
+                target_id=target.id,
+                target_name=target.name,
+                value=None,
+                warning_threshold=None,
+                alert_threshold=None,
+                comparison="gte",
+                message=f"Connection failed: {exc}",
+                checked_at=checked_at,
+            )
+        )
+    finally:
+        if conn:
+            await conn.close()
+
+    # 2) Collector freshness based on latest stored metric.
+    latest_ts = await db.scalar(select(func.max(Metric.ts)).where(Metric.target_id == target.id))
+    if latest_ts is None:
+        forced_items.append(
+            AlertStatusItem(
+                alert_key=f"std-metric-freshness-{target.id}",
+                source="standard",
+                severity="warning",
+                category="availability",
+                name="Collector Freshness",
+                description="Ensures fresh metrics are arriving for the target.",
+                target_id=target.id,
+                target_name=target.name,
+                value=None,
+                warning_threshold=None,
+                alert_threshold=None,
+                comparison="gte",
+                message="No metrics collected yet for this target.",
+                checked_at=checked_at,
+            )
+        )
+    else:
+        age_seconds = max(0.0, (checked_at - latest_ts).total_seconds())
+        rules.append(
+            _RuleInput(
+                key="collector_freshness_seconds",
+                name="Collector Freshness",
+                description="Age of the most recent metric sample.",
+                category="availability",
+                value=age_seconds,
+                warning_threshold=float(settings.poll_interval_seconds * 2),
+                alert_threshold=float(settings.poll_interval_seconds * 4),
+            )
+        )
+
+    active_connections = await _latest_metric_value(db, target.id, "connections_active")
+    total_connections = await _latest_metric_value(db, target.id, "connections_total")
+    cache_hit_ratio = await _latest_metric_value(db, target.id, "cache_hit_ratio")
+    lock_count = await _latest_metric_value(db, target.id, "locks_total")
+    checkpoints_req_delta = await _metric_delta(db, target.id, "checkpoints_req", minutes=15)
+    deadlocks_delta = await _metric_delta(db, target.id, "deadlocks", minutes=60)
+    slowest_query_mean = await _latest_query_snapshot_max(db, target.id, "mean_time")
+    slowest_query_total = await _latest_query_snapshot_max(db, target.id, "total_time")
+
+    active_ratio = None
+    if (
+        active_connections is not None
+        and total_connections is not None
+        and total_connections >= settings.alert_active_connection_ratio_min_total_connections
+    ):
+        active_ratio = active_connections / total_connections
+
+    rollback_ratio_window = settings.alert_rollback_ratio_window_minutes
+    rollback_ratio_val, tx_total_window, rollback_count_window = await _rollback_ratio_recent(
+        db,
+        target.id,
+        minutes=rollback_ratio_window,
+        min_total_transactions=settings.alert_rollback_ratio_min_total_transactions,
+        min_rollbacks=settings.alert_rollback_ratio_min_rollbacks,
+    )
+
+    rules.extend(
+        [
+            _RuleInput(
+                key="active_connections_ratio",
+                name="Active Connection Ratio",
+                description=(
+                    "Share of active sessions over total sessions. "
+                    f"Only evaluated when total sessions >= {settings.alert_active_connection_ratio_min_total_connections}."
+                ),
+                category="capacity",
+                value=active_ratio,
+                warning_threshold=0.70,
+                alert_threshold=0.90,
+            ),
+            _RuleInput(
+                key="cache_hit_ratio_low",
+                name="Cache Hit Ratio",
+                description="Low cache hit ratio means increased disk reads and slower queries.",
+                category="performance",
+                value=cache_hit_ratio,
+                warning_threshold=0.95,
+                alert_threshold=0.90,
+                comparison="lte",
+            ),
+            _RuleInput(
+                key="locks_total",
+                name="Lock Pressure",
+                description="Number of locks currently held on the target.",
+                category="contention",
+                value=lock_count,
+                warning_threshold=50,
+                alert_threshold=100,
+            ),
+            _RuleInput(
+                key="checkpoints_req_15m",
+                name="Checkpoint Pressure (15m)",
+                description="Increase of requested checkpoints in the last 15 minutes.",
+                category="io",
+                value=checkpoints_req_delta,
+                warning_threshold=5,
+                alert_threshold=15,
+            ),
+            _RuleInput(
+                key="rollback_ratio",
+                name="Rollback Ratio",
+                description=(
+                    f"Fraction of rolled back transactions in the last {rollback_ratio_window} minutes "
+                    f"(evaluated only when at least {settings.alert_rollback_ratio_min_total_transactions} "
+                    f"transactions and {settings.alert_rollback_ratio_min_rollbacks} rollbacks occurred)."
+                ),
+                category="transactions",
+                value=rollback_ratio_val,
+                warning_threshold=0.10,
+                alert_threshold=0.25,
+            ),
+            _RuleInput(
+                key="deadlocks_60m",
+                name="Deadlocks (60m)",
+                description="Increase in deadlocks during the last hour.",
+                category="contention",
+                value=deadlocks_delta,
+                warning_threshold=1,
+                alert_threshold=5,
+            ),
+            _RuleInput(
+                key="slowest_query_mean_ms",
+                name="Slowest Query Mean Time",
+                description="Highest mean execution time in the latest query snapshot.",
+                category="query",
+                value=slowest_query_mean,
+                warning_threshold=300,
+                alert_threshold=1000,
+            ),
+            _RuleInput(
+                key="slowest_query_total_ms",
+                name="Slowest Query Total Time",
+                description="Highest total execution time in the latest query snapshot.",
+                category="query",
+                value=slowest_query_total,
+                warning_threshold=3000,
+                alert_threshold=10000,
+            ),
+        ]
+    )
+    # Expose transaction volume as contextual metric for UI/debugging.
+    rules.append(
+        _RuleInput(
+            key="rollback_tx_volume_15m",
+            name="Rollback Ratio Evaluation Volume",
+            description=f"Total transactions in the last {rollback_ratio_window} minutes used for rollback-ratio evaluation.",
+            category="transactions",
+            value=tx_total_window,
+            warning_threshold=None,
+            alert_threshold=None,
+        )
+    )
+    rules.append(
+        _RuleInput(
+            key="rollback_count_window",
+            name="Rollback Count (Window)",
+            description=f"Rollback count in the last {rollback_ratio_window} minutes used for rollback-ratio evaluation.",
+            category="transactions",
+            value=rollback_count_window,
+            warning_threshold=None,
+            alert_threshold=None,
+        )
+    )
+    return rules, forced_items
+
+
+async def _evaluate_standard_alerts(db: AsyncSession, targets: list[Target]) -> list[AlertStatusItem]:
+    checked_at = datetime.now(timezone.utc)
+    items: list[AlertStatusItem] = []
+
+    for target in targets:
+        rules, forced_items = await _build_standard_rules(db, target)
+        items.extend(forced_items)
+        for rule in rules:
+            severity = _severity_from_thresholds(rule.value, rule.comparison, rule.warning_threshold, rule.alert_threshold)
+            if severity not in {"warning", "alert"}:
+                continue
+            items.append(
+                AlertStatusItem(
+                    alert_key=f"std-{rule.key}-{target.id}",
+                    source="standard",
+                    severity=severity,
+                    category=rule.category,
+                    name=rule.name,
+                    description=rule.description,
+                    target_id=target.id,
+                    target_name=target.name,
+                    value=rule.value,
+                    warning_threshold=rule.warning_threshold,
+                    alert_threshold=rule.alert_threshold,
+                    comparison=rule.comparison,
+                    message=_status_message(rule.value, rule.comparison, rule.warning_threshold, rule.alert_threshold),
+                    checked_at=checked_at,
+                )
+            )
+    return items
+
+
+async def _evaluate_custom_alerts(db: AsyncSession, targets: list[Target]) -> list[AlertStatusItem]:
+    checked_at = datetime.now(timezone.utc)
+    defs = (
+        await db.scalars(select(AlertDefinition).where(AlertDefinition.enabled.is_(True)).order_by(desc(AlertDefinition.id)))
+    ).all()
+    target_by_id = {t.id: t for t in targets}
+    items: list[AlertStatusItem] = []
+
+    for definition in defs:
+        target_candidates = targets if definition.target_id is None else [target_by_id.get(definition.target_id)]
+        for target in [t for t in target_candidates if t is not None]:
+            value: float | None = None
+            severity = "unknown"
+            message = "No data"
+            try:
+                value = await run_scalar_sql_for_target(target, definition.sql_text)
+                severity = _severity_from_thresholds(
+                    value=value,
+                    comparison=definition.comparison,
+                    warning_threshold=definition.warning_threshold,
+                    alert_threshold=definition.alert_threshold,
+                )
+                message = _status_message(value, definition.comparison, definition.warning_threshold, definition.alert_threshold)
+            except Exception as exc:
+                severity = "alert"
+                message = f"Execution failed: {exc}"
+
+            if severity not in {"warning", "alert"}:
+                continue
+            items.append(
+                AlertStatusItem(
+                    alert_key=f"custom-{definition.id}-{target.id}",
+                    source="custom",
+                    severity=severity,
+                    category="custom",
+                    name=definition.name,
+                    description=definition.description or "Custom SQL alert",
+                    target_id=target.id,
+                    target_name=target.name,
+                    value=value,
+                    warning_threshold=definition.warning_threshold,
+                    alert_threshold=definition.alert_threshold,
+                    comparison=definition.comparison,
+                    message=message,
+                    checked_at=checked_at,
+                    sql_text=definition.sql_text,
+                )
+            )
+    return items
+
+
+async def get_alert_status(db: AsyncSession, use_cache: bool = True) -> AlertStatusResponse:
+    now_seconds = time.time()
+    cached = _status_cache.get("data")
+    expires = float(_status_cache.get("expires", 0.0))
+    if use_cache and cached and expires > now_seconds:
+        return cached
+
+    targets = (await db.scalars(select(Target).order_by(Target.name.asc()))).all()
+    standard_items = await _evaluate_standard_alerts(db, targets)
+    custom_items = await _evaluate_custom_alerts(db, targets)
+    all_items = standard_items + custom_items
+
+    warnings = [item for item in all_items if item.severity == "warning"]
+    alerts = [item for item in all_items if item.severity == "alert"]
+    warnings.sort(key=lambda i: (i.target_name.lower(), i.name.lower()))
+    alerts.sort(key=lambda i: (i.target_name.lower(), i.name.lower()))
+
+    payload = AlertStatusResponse(
+        generated_at=datetime.now(timezone.utc),
+        warnings=warnings,
+        alerts=alerts,
+        warning_count=len(warnings),
+        alert_count=len(alerts),
+    )
+    _status_cache["data"] = payload
+    _status_cache["expires"] = now_seconds + _STATUS_CACHE_TTL_SECONDS
+    return payload

backend/app/services/collector.py

@@ -1,6 +1,7 @@
 import asyncio
 import logging
 from datetime import datetime, timezone
+from random import uniform
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.exc import SQLAlchemyError
@@ -13,6 +14,11 @@ import asyncpg
 
 logger = logging.getLogger(__name__)
 settings = get_settings()
+_failure_state: dict[int, dict[str, object]] = {}
+_failure_log_interval_seconds = 300
+_backoff_base_seconds = max(3, int(settings.poll_interval_seconds))
+_backoff_max_seconds = 300
+_backoff_jitter_factor = 0.15
 
 
 def build_target_dsn(target: Target) -> str:
@@ -41,7 +47,19 @@ async def collect_target(target: Target) -> None:
     try:
         stat_db = await conn.fetchrow(
             """
-            SELECT numbackends, xact_commit, xact_rollback, blks_hit, blks_read, tup_returned, tup_fetched
+            SELECT
+              numbackends,
+              xact_commit,
+              xact_rollback,
+              deadlocks,
+              temp_files,
+              temp_bytes,
+              blk_read_time,
+              blk_write_time,
+              blks_hit,
+              blks_read,
+              tup_returned,
+              tup_fetched
             FROM pg_stat_database
             WHERE datname = current_database()
             """
@@ -55,18 +73,44 @@ async def collect_target(target: Target) -> None:
             WHERE datname = current_database()
             """
         )
+        checkpointer_view_exists = await conn.fetchval("SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL")
+        bgwriter = None
+        if checkpointer_view_exists:
+            try:
+                bgwriter = await conn.fetchrow(
+                    """
+                    SELECT
+                      num_timed AS checkpoints_timed,
+                      num_requested AS checkpoints_req,
+                      0::bigint AS buffers_checkpoint,
+                      0::bigint AS buffers_clean,
+                      0::bigint AS maxwritten_clean
+                    FROM pg_stat_checkpointer
+                    """
+                )
+            except Exception:
+                bgwriter = None
+        if bgwriter is None:
+            try:
                 bgwriter = await conn.fetchrow(
                     """
                     SELECT checkpoints_timed, checkpoints_req, buffers_checkpoint, buffers_clean, maxwritten_clean
                     FROM pg_stat_bgwriter
                     """
                 )
+            except Exception:
+                bgwriter = None
 
         if stat_db is None:
             stat_db = {
                 "numbackends": 0,
                 "xact_commit": 0,
                 "xact_rollback": 0,
+                "deadlocks": 0,
+                "temp_files": 0,
+                "temp_bytes": 0,
+                "blk_read_time": 0,
+                "blk_write_time": 0,
                 "blks_hit": 0,
                 "blks_read": 0,
                 "tup_returned": 0,
@@ -89,6 +133,7 @@ async def collect_target(target: Target) -> None:
             cache_hit_ratio = stat_db["blks_hit"] / (stat_db["blks_hit"] + stat_db["blks_read"])
 
         query_rows = []
+        if target.use_pg_stat_statements:
             try:
                 query_rows = await conn.fetch(
                     """
@@ -106,6 +151,13 @@ async def collect_target(target: Target) -> None:
             await _store_metric(db, target.id, "connections_total", activity["total_connections"], {})
             await _store_metric(db, target.id, "connections_active", activity["active_connections"], {})
             await _store_metric(db, target.id, "xacts_total", stat_db["xact_commit"] + stat_db["xact_rollback"], {})
+            await _store_metric(db, target.id, "xact_commit", stat_db["xact_commit"], {})
+            await _store_metric(db, target.id, "xact_rollback", stat_db["xact_rollback"], {})
+            await _store_metric(db, target.id, "deadlocks", stat_db["deadlocks"], {})
+            await _store_metric(db, target.id, "temp_files", stat_db["temp_files"], {})
+            await _store_metric(db, target.id, "temp_bytes", stat_db["temp_bytes"], {})
+            await _store_metric(db, target.id, "blk_read_time", stat_db["blk_read_time"], {})
+            await _store_metric(db, target.id, "blk_write_time", stat_db["blk_write_time"], {})
             await _store_metric(db, target.id, "cache_hit_ratio", cache_hit_ratio, {})
             await _store_metric(db, target.id, "locks_total", lock_count, {})
             await _store_metric(db, target.id, "checkpoints_timed", bgwriter["checkpoints_timed"], {})
@@ -133,17 +185,97 @@ async def collect_once() -> None:
     async with SessionLocal() as db:
         targets = (await db.scalars(select(Target))).all()
 
+    active_target_ids = {target.id for target in targets}
+    stale_target_ids = [target_id for target_id in _failure_state.keys() if target_id not in active_target_ids]
+    for stale_target_id in stale_target_ids:
+        _failure_state.pop(stale_target_id, None)
+
     for target in targets:
+        now = datetime.now(timezone.utc)
+        state = _failure_state.get(target.id)
+        if state:
+            next_attempt_at = state.get("next_attempt_at")
+            if isinstance(next_attempt_at, datetime) and now < next_attempt_at:
+                continue
+
         try:
             await collect_target(target)
+            prev = _failure_state.pop(target.id, None)
+            if prev:
+                first_failure_at = prev.get("first_failure_at")
+                downtime_seconds = None
+                if isinstance(first_failure_at, datetime):
+                    downtime_seconds = max(0, int((now - first_failure_at).total_seconds()))
+                logger.info(
+                    "collector_target_recovered target=%s after_failures=%s downtime_seconds=%s last_error=%s",
+                    target.id,
+                    prev.get("count", 0),
+                    downtime_seconds,
+                    prev.get("error"),
+                )
         except (OSError, SQLAlchemyError, asyncpg.PostgresError, Exception) as exc:
-            logger.exception("collector_error target=%s err=%s", target.id, exc)
+            current_error = str(exc)
+            error_class = exc.__class__.__name__
+            state = _failure_state.get(target.id)
+            if state is None:
+                next_delay = min(_backoff_max_seconds, _backoff_base_seconds)
+                jitter = next_delay * _backoff_jitter_factor
+                next_delay = max(1, int(next_delay + uniform(-jitter, jitter)))
+                next_attempt_at = now.timestamp() + next_delay
+                _failure_state[target.id] = {
+                    "count": 1,
+                    "first_failure_at": now,
+                    "last_log_at": now,
+                    "error": current_error,
+                    "next_attempt_at": datetime.fromtimestamp(next_attempt_at, tz=timezone.utc),
+                }
+                logger.warning(
+                    "collector_target_unreachable target=%s error_class=%s err=%s consecutive_failures=%s retry_in_seconds=%s",
+                    target.id,
+                    error_class,
+                    current_error,
+                    1,
+                    next_delay,
+                )
+                continue
+
+            count = int(state.get("count", 0)) + 1
+            raw_backoff = min(_backoff_max_seconds, _backoff_base_seconds * (2 ** min(count - 1, 10)))
+            jitter = raw_backoff * _backoff_jitter_factor
+            next_delay = max(1, int(raw_backoff + uniform(-jitter, jitter)))
+            state["next_attempt_at"] = datetime.fromtimestamp(now.timestamp() + next_delay, tz=timezone.utc)
+
+            last_log_at = state.get("last_log_at")
+            last_logged_error = str(state.get("error", ""))
+            should_log = False
+            if current_error != last_logged_error:
+                should_log = True
+            elif isinstance(last_log_at, datetime):
+                should_log = (now - last_log_at).total_seconds() >= _failure_log_interval_seconds
+            else:
+                should_log = True
+
+            state["count"] = count
+            if should_log:
+                state["last_log_at"] = now
+                state["error"] = current_error
+                logger.warning(
+                    "collector_target_unreachable target=%s error_class=%s err=%s consecutive_failures=%s retry_in_seconds=%s",
+                    target.id,
+                    error_class,
+                    current_error,
+                    count,
+                    next_delay,
+                )
 
 
 async def collector_loop(stop_event: asyncio.Event) -> None:
     while not stop_event.is_set():
+        cycle_started = asyncio.get_running_loop().time()
         await collect_once()
+        elapsed = asyncio.get_running_loop().time() - cycle_started
+        sleep_for = max(0.0, settings.poll_interval_seconds - elapsed)
         try:
-            await asyncio.wait_for(stop_event.wait(), timeout=settings.poll_interval_seconds)
+            await asyncio.wait_for(stop_event.wait(), timeout=sleep_for)
         except asyncio.TimeoutError:
             pass

backend/app/services/infra_probe.py

@@ -17,10 +17,10 @@ class DiskSpaceProvider:
 class NullDiskSpaceProvider(DiskSpaceProvider):
     async def get_free_bytes(self, target_host: str) -> DiskSpaceProbeResult:
         return DiskSpaceProbeResult(
-            source="none",
+            source="agentless",
             status="unavailable",
             free_bytes=None,
-            message=f"No infra probe configured for host {target_host}. Add SSH/Agent provider later.",
+            message=f"Agentless mode: host-level free disk is not available for {target_host}.",
         )
 
 

backend/app/services/overview_collector.py

@@ -106,6 +106,25 @@ async def collect_overview(
         errors,
         "pg_stat_database_perf",
     )
+    checkpointer_view_exists = await _safe_fetchval(
+        conn,
+        "SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL",
+        errors,
+        "checkpointer_view_exists",
+    )
+    if checkpointer_view_exists:
+        bgwriter = await _safe_fetchrow(
+            conn,
+            """
+            SELECT
+              num_timed AS checkpoints_timed,
+              num_requested AS checkpoints_req
+            FROM pg_stat_checkpointer
+            """,
+            errors,
+            "pg_stat_checkpointer",
+        )
+    else:
         bgwriter = await _safe_fetchrow(
             conn,
             "SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter",

backend/app/services/service_info.py

@@ -0,0 +1,91 @@
+import asyncio
+import json
+import re
+from datetime import datetime, timezone
+from urllib.error import URLError
+from urllib.request import Request, urlopen
+
+UPSTREAM_REPO_WEB = "https://git.nesterovic.cc/nessi/NexaPG"
+UPSTREAM_REPO_API = "https://git.nesterovic.cc/api/v1/repos/nessi/NexaPG"
+
+
+def _extract_version(payload: str) -> str | None:
+    txt = payload.strip()
+    if not txt:
+        return None
+
+    try:
+        data = json.loads(txt)
+        if isinstance(data, dict):
+            for key in ("latest_version", "version", "tag_name", "name"):
+                value = data.get(key)
+                if isinstance(value, str) and value.strip():
+                    return value.strip()
+        if isinstance(data, list) and data and isinstance(data[0], dict):
+            for key in ("latest_version", "version", "tag_name", "name"):
+                value = data[0].get(key)
+                if isinstance(value, str) and value.strip():
+                    return value.strip()
+    except json.JSONDecodeError:
+        pass
+
+    first_line = txt.splitlines()[0].strip()
+    if first_line:
+        return first_line[:64]
+    return None
+
+
+def _parse_semver(value: str) -> tuple[int, ...] | None:
+    normalized = value.strip().lower()
+    if normalized.startswith("v"):
+        normalized = normalized[1:]
+    parts = re.findall(r"\d+", normalized)
+    if not parts:
+        return None
+    return tuple(int(p) for p in parts[:4])
+
+
+def is_update_available(current_version: str, latest_version: str) -> bool:
+    current = _parse_semver(current_version)
+    latest = _parse_semver(latest_version)
+    if current and latest:
+        max_len = max(len(current), len(latest))
+        current = current + (0,) * (max_len - len(current))
+        latest = latest + (0,) * (max_len - len(latest))
+        return latest > current
+    return latest_version.strip() != current_version.strip()
+
+
+def _get_json(url: str):
+    req = Request(url, headers={"User-Agent": "NexaPG/1.0"})
+    with urlopen(req, timeout=8) as response:
+        raw = response.read(64_000).decode("utf-8", errors="replace")
+    return json.loads(raw)
+
+
+def _fetch_latest_from_upstream_sync() -> tuple[str, str]:
+    latest_release_url = f"{UPSTREAM_REPO_API}/releases/latest"
+
+    try:
+        release = _get_json(latest_release_url)
+        if isinstance(release, dict):
+            tag = (release.get("tag_name") or release.get("name") or "").strip()
+            if tag:
+                return tag[:64], "release"
+    except Exception as exc:
+        raise ValueError(f"Could not fetch latest release from upstream repository: {exc}") from exc
+    raise ValueError("No published release found in upstream repository")
+
+
+async def fetch_latest_from_upstream() -> tuple[str | None, str | None, str | None]:
+    try:
+        latest, ref = await asyncio.to_thread(_fetch_latest_from_upstream_sync)
+        return latest, ref, None
+    except URLError as exc:
+        return None, None, f"Version check failed: {exc.reason}"
+    except Exception as exc:  # noqa: BLE001
+        return None, None, f"Version check failed: {exc}"
+
+
+def utcnow() -> datetime:
+    return datetime.now(timezone.utc)

backend/requirements.txt

@@ -1,4 +1,5 @@
-fastapi==0.116.1
+fastapi==0.129.0
+starlette==0.52.1
 uvicorn[standard]==0.35.0
 gunicorn==23.0.0
 sqlalchemy[asyncio]==2.0.44
@@ -7,7 +8,7 @@ alembic==1.16.5
 pydantic==2.11.7
 pydantic-settings==2.11.0
 email-validator==2.2.0
-python-jose[cryptography]==3.5.0
+PyJWT==2.11.0
 passlib[argon2]==1.7.4
-cryptography==45.0.7
-python-multipart==0.0.20
+cryptography==46.0.5
+python-multipart==0.0.22

backend/scripts/pg_compat_smoke.py

@@ -0,0 +1,367 @@
+import asyncio
+import os
+import sys
+from typing import Any
+
+import asyncpg
+
+
+def _required_env(name: str) -> str:
+    value = os.getenv(name, "").strip()
+    if not value:
+        raise RuntimeError(f"Missing required env var: {name}")
+    return value
+
+
+async def _connect_with_retry(dsn: str, attempts: int = 40, delay_seconds: float = 1.5) -> asyncpg.Connection:
+    last_exc: Exception | None = None
+    for _ in range(attempts):
+        try:
+            return await asyncpg.connect(dsn=dsn, timeout=5)
+        except Exception as exc:  # pragma: no cover - smoke utility
+            last_exc = exc
+            await asyncio.sleep(delay_seconds)
+    raise RuntimeError(f"Could not connect to PostgreSQL after retries: {last_exc}")
+
+
+async def _fetchrow_required(conn: asyncpg.Connection, query: str, label: str) -> dict[str, Any]:
+    row = await conn.fetchrow(query)
+    if row is None:
+        raise RuntimeError(f"{label} returned no rows")
+    return dict(row)
+
+
+async def _run_required_fetchrow(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await _fetchrow_required(conn, query, label)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_required_fetch(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await conn.fetch(query)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_required_fetchval(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await conn.fetchval(query)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_optional(conn: asyncpg.Connection, label: str, query: str) -> None:
+    try:
+        await conn.fetch(query)
+        print(f"[compat] PASS optional: {label}")
+    except Exception as exc:
+        print(f"[compat] SKIP optional: {label} ({exc})")
+
+
+async def _run_expect_failure(
+    conn: asyncpg.Connection,
+    label: str,
+    query: str,
+    accepted_sqlstates: set[str],
+) -> None:
+    try:
+        await conn.fetch(query)
+    except asyncpg.PostgresError as exc:
+        if exc.sqlstate in accepted_sqlstates:
+            print(f"[compat] PASS expected-failure: {label} (sqlstate={exc.sqlstate})")
+            return
+        raise RuntimeError(f"{label} failed with unexpected sqlstate={exc.sqlstate}: {exc}") from exc
+    except Exception as exc:
+        raise RuntimeError(f"{label} failed with unexpected non-Postgres error: {exc}") from exc
+    raise RuntimeError(f"{label} unexpectedly succeeded, but failure was expected")
+
+
+def _section(title: str) -> None:
+    print(f"[compat] --- {title} ---")
+
+
+def _dsn_candidates() -> list[str]:
+    # Preferred: explicit candidate list for CI portability (Gitea/GitHub runners).
+    raw_candidates = os.getenv("PG_DSN_CANDIDATES", "").strip()
+    if raw_candidates:
+        values = [item.strip() for item in raw_candidates.split(",") if item.strip()]
+        if values:
+            return values
+    # Backward compatible single DSN.
+    raw_single = os.getenv("PG_DSN", "").strip()
+    if raw_single:
+        return [raw_single]
+    raise RuntimeError("Missing PG_DSN or PG_DSN_CANDIDATES")
+
+
+async def run() -> None:
+    candidates = _dsn_candidates()
+    last_error: Exception | None = None
+    conn: asyncpg.Connection | None = None
+    used_dsn = ""
+    for dsn in candidates:
+        try:
+            conn = await _connect_with_retry(dsn)
+            used_dsn = dsn
+            break
+        except Exception as exc:
+            last_error = exc
+    if conn is None:
+        raise RuntimeError(f"Could not connect to PostgreSQL using candidates: {last_error}")
+
+    try:
+        version = await conn.fetchval("SHOW server_version")
+        current_db = await conn.fetchval("SELECT current_database()")
+        print(f"[compat] Connected: version={version} db={current_db} dsn={used_dsn}")
+
+        _section("connectivity")
+        await _run_required_fetchval(conn, "target_connection.select_1", "SELECT 1")
+        await _run_required_fetchval(conn, "connectivity.server_encoding", "SHOW server_encoding")
+        await _run_required_fetchval(conn, "connectivity.timezone", "SHOW TimeZone")
+
+        _section("collector")
+        # Core collector queries used in app/services/collector.py
+        await _run_required_fetchrow(
+            conn,
+            "collector.pg_stat_database",
+            """
+            SELECT
+              numbackends,
+              xact_commit,
+              xact_rollback,
+              deadlocks,
+              temp_files,
+              temp_bytes,
+              blk_read_time,
+              blk_write_time,
+              blks_hit,
+              blks_read,
+              tup_returned,
+              tup_fetched
+            FROM pg_stat_database
+            WHERE datname = current_database()
+            """,
+        )
+
+        await _run_required_fetchrow(
+            conn,
+            "collector.pg_stat_activity",
+            """
+            SELECT
+              count(*) FILTER (WHERE state = 'active') AS active_connections,
+              count(*) AS total_connections
+            FROM pg_stat_activity
+            WHERE datname = current_database()
+            """,
+        )
+
+        await _run_required_fetchval(conn, "collector.pg_locks_count", "SELECT count(*) FROM pg_locks")
+
+        # Checkpoint stats fallback (PG14/15 vs newer changes)
+        has_checkpointer = await conn.fetchval("SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL")
+        if has_checkpointer:
+            await _run_required_fetchrow(
+                conn,
+                "collector.checkpointer_view",
+                """
+                SELECT
+                  num_timed AS checkpoints_timed,
+                  num_requested AS checkpoints_req,
+                  0::bigint AS buffers_checkpoint,
+                  0::bigint AS buffers_clean,
+                  0::bigint AS maxwritten_clean
+                FROM pg_stat_checkpointer
+                """,
+            )
+            print("[compat] Using pg_stat_checkpointer")
+        else:
+            await _run_required_fetchrow(
+                conn,
+                "collector.bgwriter_view",
+                "SELECT checkpoints_timed, checkpoints_req, buffers_checkpoint, buffers_clean, maxwritten_clean FROM pg_stat_bgwriter",
+            )
+            print("[compat] Using pg_stat_bgwriter")
+
+        _section("target endpoints")
+        # Target endpoint queries used in app/api/routes/targets.py
+        await _run_required_fetch(
+            conn,
+            "target_endpoint.locks_table",
+            """
+            SELECT locktype, mode, granted, relation::regclass::text AS relation, pid
+            FROM pg_locks
+            ORDER BY granted ASC, mode
+            LIMIT 500
+            """,
+        )
+        await _run_required_fetch(
+            conn,
+            "target_endpoint.activity_table",
+            """
+            SELECT pid, usename, application_name, client_addr::text, state, wait_event_type, wait_event, now() - query_start AS running_for, left(query, 300) AS query
+            FROM pg_stat_activity
+            WHERE datname = current_database()
+            ORDER BY query_start NULLS LAST
+            LIMIT 200
+            """,
+        )
+        await _run_required_fetch(
+            conn,
+            "target_endpoint.discover_databases",
+            """
+            SELECT datname
+            FROM pg_database
+            WHERE datallowconn
+              AND NOT datistemplate
+            ORDER BY datname
+            """,
+        )
+
+        _section("overview")
+        # Overview queries used in app/services/overview_collector.py
+        await _run_required_fetchval(conn, "overview.show_server_version", "SHOW server_version")
+        await _run_required_fetchval(conn, "overview.pg_is_in_recovery", "SELECT pg_is_in_recovery()")
+        await _run_required_fetchval(conn, "overview.pg_postmaster_start_time", "SELECT pg_postmaster_start_time()")
+        await _run_required_fetchval(conn, "overview.current_database", "SELECT current_database()")
+        await _run_required_fetchval(conn, "overview.inet_server_port", "SELECT inet_server_port()")
+        await _run_required_fetchval(conn, "overview.pg_database_size_current", "SELECT pg_database_size(current_database())")
+        await _run_required_fetch(
+            conn,
+            "overview.pg_database_size_all",
+            "SELECT datname, pg_database_size(datname) AS size_bytes FROM pg_database ORDER BY size_bytes DESC",
+        )
+        await _run_required_fetch(
+            conn,
+            "overview.largest_tables",
+            """
+            SELECT schemaname, relname, pg_total_relation_size(schemaname || '.' || relname) AS size_bytes
+            FROM pg_stat_user_tables
+            ORDER BY size_bytes DESC
+            LIMIT 5
+            """,
+        )
+        await _run_required_fetchval(conn, "overview.pg_ls_waldir", "SELECT COALESCE(sum(size), 0) FROM pg_ls_waldir()")
+        await _run_required_fetchrow(
+            conn,
+            "overview.performance_pg_stat_database",
+            """
+            SELECT xact_commit, xact_rollback, deadlocks, temp_files, temp_bytes, blk_read_time, blk_write_time
+            FROM pg_stat_database
+            WHERE datname = current_database()
+            """,
+        )
+        await _run_required_fetchval(
+            conn,
+            "overview.autovacuum_activity",
+            """
+            SELECT count(*)
+            FROM pg_stat_activity
+            WHERE query ILIKE 'autovacuum:%'
+            """,
+        )
+        await _run_required_fetchval(
+            conn,
+            "overview.checkpointer_view_exists",
+            "SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL",
+        )
+        if has_checkpointer:
+            await _run_required_fetchrow(
+                conn,
+                "overview.pg_stat_checkpointer",
+                "SELECT num_timed AS checkpoints_timed, num_requested AS checkpoints_req FROM pg_stat_checkpointer",
+            )
+        else:
+            await _run_required_fetchrow(
+                conn,
+                "overview.pg_stat_bgwriter",
+                "SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter",
+            )
+
+        _section("optional paths")
+        # Optional paths that may depend on role/extension config.
+        await _run_optional(conn, "overview.replication_slots", "SELECT count(*) FROM pg_replication_slots")
+        await _run_optional(
+            conn,
+            "overview.pg_stat_replication",
+            """
+            SELECT application_name, client_addr::text, state, sync_state,
+                   EXTRACT(EPOCH FROM write_lag) AS write_lag_seconds,
+                   EXTRACT(EPOCH FROM flush_lag) AS flush_lag_seconds,
+                   EXTRACT(EPOCH FROM replay_lag) AS replay_lag_seconds,
+                   pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn) AS replay_lag_bytes
+            FROM pg_stat_replication
+            """,
+        )
+        await _run_optional(
+            conn,
+            "overview.standby_replay_lag",
+            "SELECT EXTRACT(EPOCH FROM (now() - pg_last_xact_replay_timestamp()))",
+        )
+        await _run_optional(
+            conn,
+            "collector.pg_stat_statements",
+            """
+            SELECT queryid::text, calls, total_exec_time, mean_exec_time, rows, left(query, 2000) AS query_text
+            FROM pg_stat_statements
+            ORDER BY total_exec_time DESC
+            LIMIT 20
+            """,
+        )
+        _section("pg_stat_statements modes")
+        # Validate both runtime modes NexaPG must support:
+        # 1) extension unavailable/not preloaded -> query fails with known sqlstate
+        # 2) extension available + loaded -> query succeeds
+        await conn.execute("DROP EXTENSION IF EXISTS pg_stat_statements")
+        await _run_expect_failure(
+            conn,
+            "pg_stat_statements.absent_or_not_loaded",
+            """
+            SELECT queryid::text, calls, total_exec_time, mean_exec_time, rows, left(query, 2000) AS query_text
+            FROM pg_stat_statements
+            ORDER BY total_exec_time DESC
+            LIMIT 20
+            """,
+            accepted_sqlstates={"42P01", "55000"},
+        )
+
+        available = await conn.fetchval(
+            """
+            SELECT EXISTS(
+              SELECT 1
+              FROM pg_available_extensions
+              WHERE name = 'pg_stat_statements'
+            )
+            """
+        )
+        if available:
+            try:
+                await conn.execute("CREATE EXTENSION IF NOT EXISTS pg_stat_statements")
+            except Exception as exc:
+                print(f"[compat] SKIP optional: pg_stat_statements.create_extension ({exc})")
+            else:
+                try:
+                    await conn.fetch(
+                        """
+                        SELECT queryid::text, calls, total_exec_time, mean_exec_time, rows, left(query, 2000) AS query_text
+                        FROM pg_stat_statements
+                        ORDER BY total_exec_time DESC
+                        LIMIT 20
+                        """
+                    )
+                    print("[compat] PASS optional: pg_stat_statements.enabled_query")
+                except asyncpg.PostgresError as exc:
+                    # Typical when shared_preload_libraries does not include pg_stat_statements.
+                    if exc.sqlstate == "55000":
+                        print(f"[compat] SKIP optional: pg_stat_statements.enabled_query ({exc})")
+                    else:
+                        raise RuntimeError(f"pg_stat_statements.enabled_query unexpected sqlstate={exc.sqlstate}: {exc}") from exc
+        else:
+            print("[compat] SKIP optional: pg_stat_statements.extension_unavailable")
+
+        print("[compat] Smoke checks passed")
+    finally:
+        await conn.close()
+
+
+if __name__ == "__main__":
+    try:
+        asyncio.run(run())
+    except Exception as exc:  # pragma: no cover - smoke utility
+        print(f"[compat] FAILED: {exc}", file=sys.stderr)
+        raise

docker-compose.yml

@@ -18,8 +18,8 @@ services:
       retries: 10
 
   backend:
-    build:
-      context: ./backend
+    image: nesterovicit/nexapg-backend:latest
+    pull_policy: always
     container_name: nexapg-backend
     restart: unless-stopped
     environment:
@@ -47,16 +47,14 @@ services:
       - "${BACKEND_PORT}:8000"
 
   frontend:
-    build:
-      context: ./frontend
-      args:
-        VITE_API_URL: ${VITE_API_URL}
+    image: nesterovicit/nexapg-frontend:latest
+    pull_policy: always
     container_name: nexapg-frontend
     restart: unless-stopped
     depends_on:
       - backend
     ports:
-      - "${FRONTEND_PORT}:80"
+      - "${FRONTEND_PORT}:8080"
 
 volumes:
   pg_data:

frontend/Dockerfile

@@ -7,8 +7,9 @@ ARG VITE_API_URL=/api/v1
 ENV VITE_API_URL=${VITE_API_URL}
 RUN npm run build
 
-FROM nginx:1.29-alpine
+FROM nginxinc/nginx-unprivileged:stable-alpine
 COPY nginx.conf /etc/nginx/conf.d/default.conf
 COPY --from=build /app/dist /usr/share/nginx/html
-EXPOSE 80
-HEALTHCHECK --interval=30s --timeout=3s --retries=5 CMD wget -qO- http://127.0.0.1/ || exit 1
+USER 101
+EXPOSE 8080
+HEALTHCHECK --interval=30s --timeout=3s --retries=5 CMD nginx -t || exit 1

frontend/index.html

@@ -3,6 +3,7 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <title>NexaPG Monitor</title>
   </head>
   <body>

frontend/nginx.conf

@@ -1,5 +1,5 @@
 server {
-  listen 80;
+  listen 8080;
   server_name _;
 
   root /usr/share/nginx/html;

frontend/src/App.jsx

@@ -1,12 +1,15 @@
 import React from "react";
-import { NavLink, Navigate, Route, Routes, useLocation } from "react-router-dom";
+import { NavLink, Navigate, Route, Routes, useLocation, useNavigate } from "react-router-dom";
 import { useAuth } from "./state";
 import { LoginPage } from "./pages/LoginPage";
 import { DashboardPage } from "./pages/DashboardPage";
 import { TargetsPage } from "./pages/TargetsPage";
 import { TargetDetailPage } from "./pages/TargetDetailPage";
 import { QueryInsightsPage } from "./pages/QueryInsightsPage";
+import { AlertsPage } from "./pages/AlertsPage";
 import { AdminUsersPage } from "./pages/AdminUsersPage";
+import { ServiceInfoPage } from "./pages/ServiceInfoPage";
+import { UserSettingsPage } from "./pages/UserSettingsPage";
 
 function Protected({ children }) {
   const { tokens } = useAuth();
@@ -16,40 +19,136 @@ function Protected({ children }) {
 }
 
 function Layout({ children }) {
-  const { me, logout } = useAuth();
+  const { me, logout, uiMode, setUiMode, alertToasts, dismissAlertToast, serviceUpdateAvailable } = useAuth();
+  const navigate = useNavigate();
   const navClass = ({ isActive }) => `nav-btn${isActive ? " active" : ""}`;
+  const fullName = [me?.first_name, me?.last_name].filter(Boolean).join(" ").trim();
 
   return (
     <div className="shell">
       <aside className="sidebar">
+        <div className="brand">
+          <img src="/nexapg-logo.svg" alt="NexaPG" className="brand-logo" />
           <h1>NexaPG</h1>
+        </div>
         <nav className="sidebar-nav">
           <NavLink to="/" end className={navClass}>
-            <span className="nav-icon">DB</span>
+            <span className="nav-icon" aria-hidden="true">
+              <svg viewBox="0 0 24 24">
+                <path d="M4 6c0-1.7 3.6-3 8-3s8 1.3 8 3-3.6 3-8 3-8-1.3-8-3zm0 6c0 1.7 3.6 3 8 3s8-1.3 8-3M4 18c0 1.7 3.6 3 8 3s8-1.3 8-3" />
+              </svg>
+            </span>
             <span className="nav-label">Dashboard</span>
           </NavLink>
           <NavLink to="/targets" className={navClass}>
-            <span className="nav-icon">TG</span>
+            <span className="nav-icon" aria-hidden="true">
+              <svg viewBox="0 0 24 24">
+                <path d="M12 3l8 4.5v9L12 21l-8-4.5v-9L12 3zM12 12l8-4.5M12 12L4 7.5M12 12v9" />
+              </svg>
+            </span>
             <span className="nav-label">Targets</span>
           </NavLink>
           <NavLink to="/query-insights" className={navClass}>
-            <span className="nav-icon">QI</span>
+            <span className="nav-icon" aria-hidden="true">
+              <svg viewBox="0 0 24 24">
+                <path d="M4 19h16M7 15l3-3 3 2 4-5M18 8h.01" />
+              </svg>
+            </span>
             <span className="nav-label">Query Insights</span>
           </NavLink>
+          <NavLink to="/alerts" className={navClass}>
+            <span className="nav-icon" aria-hidden="true">
+              <svg viewBox="0 0 24 24">
+                <path d="M15 17h5l-1.4-1.4A2 2 0 0 1 18 14.2V10a6 6 0 0 0-12 0v4.2a2 2 0 0 1-.6 1.4L4 17h5m6 0a3 3 0 0 1-6 0" />
+              </svg>
+            </span>
+            <span className="nav-label">Alerts</span>
+          </NavLink>
+          <NavLink
+            to="/service-info"
+            className={({ isActive }) => `nav-btn${isActive ? " active" : ""}${serviceUpdateAvailable ? " update-available" : ""}`}
+          >
+            <span className="nav-icon" aria-hidden="true">
+              <svg viewBox="0 0 24 24">
+                <path d="M12 22a10 10 0 1 0 0-20 10 10 0 0 0 0 20zm0-11v6m0-10h.01" />
+              </svg>
+            </span>
+            <span className="nav-label">Service Information</span>
+          </NavLink>
           {me?.role === "admin" && (
-            <NavLink to="/admin/users" className={navClass}>
-              <span className="nav-icon">AD</span>
+            <>
+              <div className="sidebar-nav-spacer" aria-hidden="true" />
+              <NavLink to="/admin/users" className={({ isActive }) => `nav-btn admin-nav${isActive ? " active" : ""}`}>
+                <span className="nav-icon" aria-hidden="true">
+                  <svg viewBox="0 0 24 24">
+                    <path d="M12 12a4 4 0 1 0 0-8 4 4 0 0 0 0 8zm-7 8a7 7 0 0 1 14 0" />
+                  </svg>
+                </span>
                 <span className="nav-label">Admin</span>
               </NavLink>
+            </>
           )}
         </nav>
         <div className="profile">
-          <div>{me?.email}</div>
-          <div className="role">{me?.role}</div>
+          <div className="mode-switch-block">
+            <div className="mode-switch-label">View Mode</div>
+            <button
+              className={`mode-toggle ${uiMode === "easy" ? "easy" : "dba"}`}
+              onClick={() => setUiMode(uiMode === "easy" ? "dba" : "easy")}
+              type="button"
+            >
+              <span className="mode-pill">Easy</span>
+              <span className="mode-pill">DBA</span>
+            </button>
+            <small>{uiMode === "easy" ? "Simple health guidance" : "Advanced DBA metrics"}</small>
+          </div>
+          <div className="profile-name">{fullName || me?.email}</div>
+          {fullName && <div className="profile-email">{me?.email}</div>}
+          <div className="role profile-role">{me?.role}</div>
+          <NavLink to="/user-settings" className={({ isActive }) => `profile-btn${isActive ? " active" : ""}`}>
+            User Settings
+          </NavLink>
           <button className="logout-btn" onClick={logout}>Logout</button>
         </div>
       </aside>
-      <main className="main">{children}</main>
+      <main className="main">
+        {children}
+        <div className="toast-stack" aria-live="polite" aria-atomic="true">
+          {alertToasts.map((toast) => (
+            <div key={toast.id} className={`alert-toast ${toast.severity || "warning"}${toast.closing ? " closing" : ""}`}>
+              <div className="alert-toast-head">
+                <strong>{toast.severity === "alert" ? "New Alert" : "New Warning"}</strong>
+                <div className="toast-actions">
+                  <button
+                    type="button"
+                    className="toast-view"
+                    title="Open in Alerts"
+                    onClick={() => {
+                      navigate(`/alerts?open=${encodeURIComponent(toast.alertKey || "")}`);
+                      dismissAlertToast(toast.id);
+                    }}
+                  >
+                    <span aria-hidden="true">
+                      <svg viewBox="0 0 24 24" width="13" height="13">
+                        <path
+                          d="M2 12s3.5-6 10-6 10 6 10 6-3.5 6-10 6-10-6-10-6zm10 3a3 3 0 1 0 0-6 3 3 0 0 0 0 6z"
+                          fill="currentColor"
+                        />
+                      </svg>
+                    </span>
+                  </button>
+                  <button type="button" className="toast-close" onClick={() => dismissAlertToast(toast.id)}>
+                    x
+                  </button>
+                </div>
+              </div>
+              <div className="alert-toast-title">{toast.title}</div>
+              <div className="alert-toast-target">{toast.target}</div>
+              <div className="alert-toast-message">{toast.message}</div>
+            </div>
+          ))}
+        </div>
+      </main>
     </div>
   );
 }
@@ -68,6 +167,9 @@ export function App() {
                 <Route path="/targets" element={<TargetsPage />} />
                 <Route path="/targets/:id" element={<TargetDetailPage />} />
                 <Route path="/query-insights" element={<QueryInsightsPage />} />
+                <Route path="/alerts" element={<AlertsPage />} />
+                <Route path="/service-info" element={<ServiceInfoPage />} />
+                <Route path="/user-settings" element={<UserSettingsPage />} />
                 <Route path="/admin/users" element={<AdminUsersPage />} />
               </Routes>
             </Layout>

frontend/src/api.js

@@ -35,8 +35,21 @@ export async function apiFetch(path, options = {}, tokens, onUnauthorized) {
     }
   }
   if (!res.ok) {
-    const txt = await res.text();
-    throw new Error(txt || `HTTP ${res.status}`);
+    const raw = await res.text();
+    let parsed = null;
+    try {
+      parsed = raw ? JSON.parse(raw) : null;
+    } catch {
+      parsed = null;
+    }
+
+    const message = parsed?.message || raw || `HTTP ${res.status}`;
+    const err = new Error(message);
+    err.status = res.status;
+    err.code = parsed?.code || null;
+    err.details = parsed?.details || null;
+    err.requestId = parsed?.request_id || res.headers.get("x-request-id") || null;
+    throw err;
   }
   if (res.status === 204) return null;
   return res.json();

frontend/src/pages/AdminUsersPage.jsx

@@ -2,27 +2,87 @@ import React, { useEffect, useState } from "react";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
 
+const TEMPLATE_VARIABLES = [
+  "target_name",
+  "target_id",
+  "alert_name",
+  "severity",
+  "category",
+  "description",
+  "message",
+  "value",
+  "warning_threshold",
+  "alert_threshold",
+  "checked_at",
+  "alert_key",
+];
+
 export function AdminUsersPage() {
   const { tokens, refresh, me } = useAuth();
+  const emptyCreateForm = { email: "", first_name: "", last_name: "", password: "", role: "viewer" };
   const [users, setUsers] = useState([]);
-  const [form, setForm] = useState({ email: "", password: "", role: "viewer" });
+  const [form, setForm] = useState(emptyCreateForm);
+  const [editingUserId, setEditingUserId] = useState(null);
+  const [editForm, setEditForm] = useState({ email: "", first_name: "", last_name: "", password: "", role: "viewer" });
+  const [emailSettings, setEmailSettings] = useState({
+    enabled: false,
+    smtp_host: "",
+    smtp_port: 587,
+    smtp_username: "",
+    smtp_password: "",
+    clear_smtp_password: false,
+    from_name: "",
+    from_email: "",
+    use_starttls: true,
+    use_ssl: false,
+    warning_subject_template: "",
+    alert_subject_template: "",
+    warning_body_template: "",
+    alert_body_template: "",
+  });
+  const [smtpState, setSmtpState] = useState({ has_password: false, updated_at: null });
+  const [testRecipient, setTestRecipient] = useState("");
+  const [smtpInfo, setSmtpInfo] = useState("");
   const [error, setError] = useState("");
 
   const load = async () => {
-    setUsers(await apiFetch("/admin/users", {}, tokens, refresh));
+    const [userRows, smtp] = await Promise.all([
+      apiFetch("/admin/users", {}, tokens, refresh),
+      apiFetch("/admin/settings/email", {}, tokens, refresh),
+    ]);
+    setUsers(userRows);
+    setEmailSettings((prev) => ({
+      ...prev,
+      enabled: !!smtp.enabled,
+      smtp_host: smtp.smtp_host || "",
+      smtp_port: smtp.smtp_port || 587,
+      smtp_username: smtp.smtp_username || "",
+      smtp_password: "",
+      clear_smtp_password: false,
+      from_name: smtp.from_name || "",
+      from_email: smtp.from_email || "",
+      use_starttls: !!smtp.use_starttls,
+      use_ssl: !!smtp.use_ssl,
+      warning_subject_template: smtp.warning_subject_template || "",
+      alert_subject_template: smtp.alert_subject_template || "",
+      warning_body_template: smtp.warning_body_template || "",
+      alert_body_template: smtp.alert_body_template || "",
+    }));
+    setSmtpState({ has_password: !!smtp.has_password, updated_at: smtp.updated_at });
+    setTestRecipient(smtp.from_email || "");
   };
 
   useEffect(() => {
     if (me?.role === "admin") load().catch((e) => setError(String(e.message || e)));
   }, [me]);
 
-  if (me?.role !== "admin") return <div className="card">Nur fuer Admin.</div>;
+  if (me?.role !== "admin") return <div className="card">Admins only.</div>;
 
   const create = async (e) => {
     e.preventDefault();
     try {
       await apiFetch("/admin/users", { method: "POST", body: JSON.stringify(form) }, tokens, refresh);
-      setForm({ email: "", password: "", role: "viewer" });
+      setForm(emptyCreateForm);
       await load();
     } catch (e) {
       setError(String(e.message || e));
@@ -38,30 +98,158 @@ export function AdminUsersPage() {
     }
   };
 
+  const startEdit = (user) => {
+    setEditingUserId(user.id);
+    setEditForm({
+      email: user.email || "",
+      first_name: user.first_name || "",
+      last_name: user.last_name || "",
+      password: "",
+      role: user.role || "viewer",
+    });
+  };
+
+  const cancelEdit = () => {
+    setEditingUserId(null);
+    setEditForm({ email: "", first_name: "", last_name: "", password: "", role: "viewer" });
+  };
+
+  const saveEdit = async (userId) => {
+    try {
+      const payload = {
+        email: editForm.email,
+        first_name: editForm.first_name.trim() || null,
+        last_name: editForm.last_name.trim() || null,
+        role: editForm.role,
+      };
+      if (editForm.password.trim()) payload.password = editForm.password;
+      await apiFetch(`/admin/users/${userId}`, { method: "PUT", body: JSON.stringify(payload) }, tokens, refresh);
+      cancelEdit();
+      await load();
+    } catch (e) {
+      setError(String(e.message || e));
+    }
+  };
+
+  const saveSmtp = async (e) => {
+    e.preventDefault();
+    setError("");
+    setSmtpInfo("");
+    try {
+      const payload = {
+        ...emailSettings,
+        smtp_host: emailSettings.smtp_host.trim() || null,
+        smtp_username: emailSettings.smtp_username.trim() || null,
+        from_name: emailSettings.from_name.trim() || null,
+        from_email: emailSettings.from_email.trim() || null,
+        smtp_password: emailSettings.smtp_password || null,
+        warning_subject_template: emailSettings.warning_subject_template.trim() || null,
+        alert_subject_template: emailSettings.alert_subject_template.trim() || null,
+        warning_body_template: emailSettings.warning_body_template.trim() || null,
+        alert_body_template: emailSettings.alert_body_template.trim() || null,
+      };
+      await apiFetch("/admin/settings/email", { method: "PUT", body: JSON.stringify(payload) }, tokens, refresh);
+      setSmtpInfo("SMTP settings saved.");
+      await load();
+    } catch (e) {
+      setError(String(e.message || e));
+    }
+  };
+
+  const sendTestMail = async () => {
+    setError("");
+    setSmtpInfo("");
+    try {
+      const recipient = testRecipient.trim();
+      if (!recipient) {
+        throw new Error("Please enter a test recipient email.");
+      }
+      await apiFetch(
+        "/admin/settings/email/test",
+        { method: "POST", body: JSON.stringify({ recipient }) },
+        tokens,
+        refresh
+      );
+      setSmtpInfo(`Test email sent to ${recipient}.`);
+    } catch (e) {
+      setError(String(e.message || e));
+    }
+  };
+
+  const protocolMode = emailSettings.use_ssl ? "ssl" : emailSettings.use_starttls ? "starttls" : "plain";
+  const setProtocolMode = (mode) => {
+    if (mode === "ssl") {
+      setEmailSettings({ ...emailSettings, use_ssl: true, use_starttls: false });
+      return;
+    }
+    if (mode === "starttls") {
+      setEmailSettings({ ...emailSettings, use_ssl: false, use_starttls: true });
+      return;
+    }
+    setEmailSettings({ ...emailSettings, use_ssl: false, use_starttls: false });
+  };
+
   return (
-    <div>
-      <h2>Admin Users</h2>
+    <div className="admin-settings-page">
+      <h2>Admin Settings</h2>
+      <p className="muted admin-page-subtitle">Manage users and outgoing notifications for this NexaPG instance.</p>
       {error && <div className="card error">{error}</div>}
-      <form className="card grid three" onSubmit={create}>
-        <input value={form.email} placeholder="email" onChange={(e) => setForm({ ...form, email: e.target.value })} />
+
+      <div className="card">
+        <div className="admin-section-head">
+          <h3>User Management</h3>
+          <p className="muted">Create accounts and manage access roles.</p>
+        </div>
+        <form className="grid three admin-user-form" onSubmit={create}>
+          <div className="admin-field">
+            <label>First Name</label>
+            <input
+              value={form.first_name}
+              placeholder="Jane"
+              onChange={(e) => setForm({ ...form, first_name: e.target.value })}
+            />
+          </div>
+          <div className="admin-field">
+            <label>Last Name</label>
+            <input
+              value={form.last_name}
+              placeholder="Doe"
+              onChange={(e) => setForm({ ...form, last_name: e.target.value })}
+            />
+          </div>
+          <div className="admin-field">
+            <label>Email</label>
+            <input value={form.email} placeholder="user@example.com" onChange={(e) => setForm({ ...form, email: e.target.value })} />
+          </div>
+          <div className="admin-field">
+            <label>Password</label>
             <input
               type="password"
               value={form.password}
-          placeholder="passwort"
+              placeholder="Set initial password"
               onChange={(e) => setForm({ ...form, password: e.target.value })}
             />
+          </div>
+          <div className="admin-field">
+            <label>Role</label>
             <select value={form.role} onChange={(e) => setForm({ ...form, role: e.target.value })}>
               <option value="viewer">viewer</option>
               <option value="operator">operator</option>
               <option value="admin">admin</option>
             </select>
-        <button>User anlegen</button>
+          </div>
+          <div className="form-actions field-full">
+            <button className="primary-btn" type="submit">Create User</button>
+          </div>
         </form>
-      <div className="card">
+      </div>
+
+      <div className="card admin-users-table-wrap">
         <table>
           <thead>
             <tr>
               <th>ID</th>
+              <th>Name</th>
               <th>Email</th>
               <th>Role</th>
               <th>Action</th>
@@ -69,16 +257,273 @@ export function AdminUsersPage() {
           </thead>
           <tbody>
             {users.map((u) => (
-              <tr key={u.id}>
-                <td>{u.id}</td>
-                <td>{u.email}</td>
-                <td>{u.role}</td>
-                <td>{u.id !== me.id && <button onClick={() => remove(u.id)}>Delete</button>}</td>
+              <tr key={u.id} className="admin-user-row">
+                <td className="user-col-id">{u.id}</td>
+                <td className="user-col-name">
+                  {editingUserId === u.id ? (
+                    <div className="admin-inline-grid two">
+                      <input
+                        value={editForm.first_name}
+                        placeholder="First name"
+                        onChange={(e) => setEditForm({ ...editForm, first_name: e.target.value })}
+                      />
+                      <input
+                        value={editForm.last_name}
+                        placeholder="Last name"
+                        onChange={(e) => setEditForm({ ...editForm, last_name: e.target.value })}
+                      />
+                    </div>
+                  ) : (
+                    <span className="user-col-name-value">{[u.first_name, u.last_name].filter(Boolean).join(" ") || "-"}</span>
+                  )}
+                </td>
+                <td className="user-col-email">
+                  {editingUserId === u.id ? (
+                    <input
+                      value={editForm.email}
+                      placeholder="user@example.com"
+                      onChange={(e) => setEditForm({ ...editForm, email: e.target.value })}
+                    />
+                  ) : (
+                    u.email
+                  )}
+                </td>
+                <td>
+                  {editingUserId === u.id ? (
+                    <select value={editForm.role} onChange={(e) => setEditForm({ ...editForm, role: e.target.value })}>
+                      <option value="viewer">viewer</option>
+                      <option value="operator">operator</option>
+                      <option value="admin">admin</option>
+                    </select>
+                  ) : (
+                    <span className={`pill role-pill role-${u.role}`}>{u.role}</span>
+                  )}
+                </td>
+                <td className="admin-user-actions">
+                  {editingUserId === u.id && (
+                    <input
+                      type="password"
+                      className="admin-inline-password"
+                      value={editForm.password}
+                      placeholder="New password (optional)"
+                      onChange={(e) => setEditForm({ ...editForm, password: e.target.value })}
+                    />
+                  )}
+                  {editingUserId === u.id ? (
+                    <>
+                      <button className="table-action-btn primary small-btn" onClick={() => saveEdit(u.id)}>
+                        Save
+                      </button>
+                      <button className="table-action-btn small-btn" onClick={cancelEdit}>
+                        Cancel
+                      </button>
+                    </>
+                  ) : (
+                    <button className="table-action-btn edit small-btn" onClick={() => startEdit(u)}>
+                      Edit
+                    </button>
+                  )}
+                  {u.id !== me.id && (
+                    <button className="table-action-btn delete small-btn" onClick={() => remove(u.id)}>
+                      <span aria-hidden="true">
+                        <svg viewBox="0 0 24 24" width="12" height="12">
+                          <path
+                            d="M9 3h6l1 2h4v2H4V5h4l1-2zm1 6h2v8h-2V9zm4 0h2v8h-2V9zM7 9h2v8H7V9z"
+                            fill="currentColor"
+                          />
+                        </svg>
+                      </span>
+                      <span>Delete</span>
+                    </button>
+                  )}
+                </td>
               </tr>
             ))}
           </tbody>
         </table>
       </div>
+
+      <div className="card">
+        <div className="admin-section-head">
+          <h3>Alert Email Notifications (SMTP)</h3>
+          <p className="muted">Configure send-only SMTP for warning and alert notifications.</p>
+        </div>
+        {smtpInfo && <div className="test-connection-result ok">{smtpInfo}</div>}
+        <form className="grid two admin-smtp-form" onSubmit={saveSmtp}>
+          <div className="admin-subcard field-full">
+            <h4>SMTP Settings</h4>
+            <div className="grid two">
+              <label className="toggle-check field-full">
+                <input
+                  type="checkbox"
+                  checked={emailSettings.enabled}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, enabled: e.target.checked })}
+                />
+                <span className="toggle-ui" />
+                <span>
+                  <strong>Enable alert emails</strong>
+                </span>
+              </label>
+
+              <div className="admin-field">
+                <label>SMTP host</label>
+                <input
+                  value={emailSettings.smtp_host}
+                  placeholder="smtp.example.com"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, smtp_host: e.target.value })}
+                />
+              </div>
+              <div className="admin-field">
+                <label>SMTP port</label>
+                <input
+                  type="number"
+                  value={emailSettings.smtp_port}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, smtp_port: Number(e.target.value || 587) })}
+                />
+              </div>
+
+              <div className="admin-field">
+                <label>SMTP username</label>
+                <input
+                  value={emailSettings.smtp_username}
+                  placeholder="alerts@example.com"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, smtp_username: e.target.value })}
+                />
+              </div>
+              <div className="admin-field">
+                <label>SMTP password</label>
+                <input
+                  type="password"
+                  value={emailSettings.smtp_password}
+                  placeholder={smtpState.has_password ? "Stored (enter to replace)" : "Set password"}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, smtp_password: e.target.value, clear_smtp_password: false })}
+                />
+              </div>
+
+              <div className="admin-field">
+                <label>From name</label>
+                <input
+                  value={emailSettings.from_name}
+                  placeholder="NexaPG Alerts"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, from_name: e.target.value })}
+                />
+              </div>
+              <div className="admin-field">
+                <label>From email</label>
+                <input
+                  value={emailSettings.from_email}
+                  placeholder="noreply@example.com"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, from_email: e.target.value })}
+                />
+              </div>
+
+              <div className="admin-field field-full">
+                <label>Transport mode</label>
+                <div className="smtp-mode-picker" role="radiogroup" aria-label="SMTP transport mode">
+                  <button
+                    type="button"
+                    className={`smtp-mode-btn ${protocolMode === "starttls" ? "active" : ""}`}
+                    aria-pressed={protocolMode === "starttls"}
+                    onClick={() => setProtocolMode("starttls")}
+                  >
+                    STARTTLS
+                  </button>
+                  <button
+                    type="button"
+                    className={`smtp-mode-btn ${protocolMode === "ssl" ? "active" : ""}`}
+                    aria-pressed={protocolMode === "ssl"}
+                    onClick={() => setProtocolMode("ssl")}
+                  >
+                    SSL/TLS (SMTPS)
+                  </button>
+                  <button
+                    type="button"
+                    className={`smtp-mode-btn ${protocolMode === "plain" ? "active" : ""}`}
+                    aria-pressed={protocolMode === "plain"}
+                    onClick={() => setProtocolMode("plain")}
+                  >
+                    No TLS
+                  </button>
+                </div>
+                <small className="muted">Select exactly one mode to avoid STARTTLS/SSL conflicts.</small>
+              </div>
+
+              <label className="toggle-check field-full">
+                <input
+                  type="checkbox"
+                  checked={emailSettings.clear_smtp_password}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, clear_smtp_password: e.target.checked, smtp_password: e.target.checked ? "" : emailSettings.smtp_password })}
+                />
+                <span className="toggle-ui" />
+                <span>Clear stored SMTP password</span>
+              </label>
+            </div>
+          </div>
+
+          <div className="admin-subcard field-full">
+            <h4>Template Settings</h4>
+            <p className="muted template-help-text">
+              If a template field is left empty, NexaPG automatically uses the built-in default template.
+            </p>
+            <div className="template-vars-grid">
+              {TEMPLATE_VARIABLES.map((item) => (
+                <code key={item} className="template-var-pill">
+                  {"{" + item + "}"}
+                </code>
+              ))}
+            </div>
+
+            <div className="grid two">
+              <div className="admin-field field-full">
+                <label>Warning subject template</label>
+                <input
+                  value={emailSettings.warning_subject_template}
+                  placeholder="[NexaPG][WARNING] {target_name} - {alert_name}"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, warning_subject_template: e.target.value })}
+                />
+              </div>
+              <div className="admin-field field-full">
+                <label>Alert subject template</label>
+                <input
+                  value={emailSettings.alert_subject_template}
+                  placeholder="[NexaPG][ALERT] {target_name} - {alert_name}"
+                  onChange={(e) => setEmailSettings({ ...emailSettings, alert_subject_template: e.target.value })}
+                />
+              </div>
+              <div className="admin-field field-full">
+                <label>Warning body template</label>
+                <textarea
+                  value={emailSettings.warning_body_template}
+                  placeholder={"Severity: {severity}\nTarget: {target_name} (id={target_id})\nAlert: {alert_name}\nMessage: {message}\nChecked At: {checked_at}"}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, warning_body_template: e.target.value })}
+                />
+              </div>
+              <div className="admin-field field-full">
+                <label>Alert body template</label>
+                <textarea
+                  value={emailSettings.alert_body_template}
+                  placeholder={"Severity: {severity}\nTarget: {target_name} (id={target_id})\nAlert: {alert_name}\nMessage: {message}\nCurrent Value: {value}\nWarning Threshold: {warning_threshold}\nAlert Threshold: {alert_threshold}\nChecked At: {checked_at}\nAlert Key: {alert_key}"}
+                  onChange={(e) => setEmailSettings({ ...emailSettings, alert_body_template: e.target.value })}
+                />
+              </div>
+            </div>
+          </div>
+
+          <div className="form-actions field-full">
+            <input
+              className="admin-test-recipient"
+              value={testRecipient}
+              placeholder="test recipient email"
+              onChange={(e) => setTestRecipient(e.target.value)}
+            />
+            <button className="secondary-btn" type="button" onClick={sendTestMail}>Send Test Mail</button>
+            <button className="primary-btn" type="submit">Save SMTP Settings</button>
+          </div>
+          <small className="muted field-full">
+            Last updated: {smtpState.updated_at ? new Date(smtpState.updated_at).toLocaleString() : "not configured yet"}
+          </small>
+        </form>
+      </div>
     </div>
   );
 }

frontend/src/pages/AlertsPage.jsx

@@ -0,0 +1,524 @@
+import React, { useEffect, useMemo, useState } from "react";
+import { useLocation } from "react-router-dom";
+import { apiFetch } from "../api";
+import { useAuth } from "../state";
+
+const initialForm = {
+  name: "",
+  description: "",
+  target_id: "",
+  sql_text: "SELECT count(*)::float FROM pg_stat_activity WHERE state = 'active'",
+  comparison: "gte",
+  warning_threshold: "",
+  alert_threshold: "",
+  enabled: true,
+};
+
+function formatAlertValue(value) {
+  if (value === null || value === undefined) return "-";
+  if (Number.isInteger(value)) return String(value);
+  return Number(value).toFixed(2);
+}
+
+function formatTs(ts) {
+  if (!ts) return "-";
+  return new Date(ts).toLocaleString();
+}
+
+function buildAlertSuggestions(item) {
+  const name = (item?.name || "").toLowerCase();
+  const category = (item?.category || "").toLowerCase();
+  const source = (item?.source || "").toLowerCase();
+  const value = Number(item?.value || 0);
+  const suggestions = [];
+
+  if (name.includes("reachability") || name.includes("connectivity") || category === "availability") {
+    suggestions.push("Verify host, port, firewall rules, and network routing between backend container and DB target.");
+    suggestions.push("Check PostgreSQL `listen_addresses` and `pg_hba.conf` on the monitored instance.");
+  }
+  if (name.includes("freshness") || item?.message?.toLowerCase().includes("no metrics")) {
+    suggestions.push("Check collector logs and polling interval. Confirm the target credentials are still valid.");
+    suggestions.push("Run a manual connection test in Targets Management and verify SSL mode.");
+  }
+  if (name.includes("cache hit") || category === "performance") {
+    suggestions.push("Inspect slow queries and add/adjust indexes for frequent WHERE/JOIN columns.");
+    suggestions.push("Review shared buffers and query patterns that cause high disk reads.");
+  }
+  if (name.includes("lock") || category === "contention") {
+    suggestions.push("Inspect blocking sessions in `pg_stat_activity` and long transactions.");
+    suggestions.push("Reduce transaction scope/duration and add missing indexes to avoid lock escalation.");
+  }
+  if (name.includes("deadlock")) {
+    suggestions.push("Enforce a consistent table access order in transactions to prevent deadlocks.");
+    suggestions.push("Retry deadlocked transactions in the application with backoff.");
+  }
+  if (name.includes("checkpoint") || category === "io") {
+    suggestions.push("Review `max_wal_size`, `checkpoint_timeout`, and write burst patterns.");
+    suggestions.push("Check disk throughput and WAL pressure during peak load.");
+  }
+  if (name.includes("rollback")) {
+    suggestions.push("Investigate application errors causing transaction rollbacks.");
+    suggestions.push("Validate constraints/input earlier to reduce failed writes.");
+  }
+  if (name.includes("query") || category === "query" || source === "custom") {
+    suggestions.push("Run `EXPLAIN (ANALYZE, BUFFERS)` for the affected query and optimize highest-cost nodes.");
+    suggestions.push("Prioritize fixes for high total-time queries first, then high mean-time queries.");
+  }
+  if (value > 0 && item?.comparison && item?.alert_threshold !== null && item?.alert_threshold !== undefined) {
+    suggestions.push(`Current value is ${value.toFixed(2)} with threshold rule ${item.comparison} ${Number(item.alert_threshold).toFixed(2)}.`);
+  }
+  if (!suggestions.length) {
+    suggestions.push("Start with target activity, locks, and query insights to isolate the root cause.");
+    suggestions.push("Compare current values to the last stable period and tune threshold sensitivity if needed.");
+  }
+
+  return suggestions.slice(0, 4);
+}
+
+export function AlertsPage() {
+  const location = useLocation();
+  const { tokens, refresh, me, alertStatus } = useAuth();
+  const [targets, setTargets] = useState([]);
+  const [definitions, setDefinitions] = useState([]);
+  const [form, setForm] = useState(initialForm);
+  const [expandedKey, setExpandedKey] = useState("");
+  const [error, setError] = useState("");
+  const [loading, setLoading] = useState(true);
+  const [standardReference, setStandardReference] = useState([]);
+  const [testing, setTesting] = useState(false);
+  const [testResult, setTestResult] = useState("");
+  const [saving, setSaving] = useState(false);
+
+  const canManageAlerts = me?.role === "admin" || me?.role === "operator";
+
+  const loadAll = async () => {
+    try {
+      setError("");
+      const [targetRows, referenceRows] = await Promise.all([
+        apiFetch("/targets", {}, tokens, refresh),
+        apiFetch("/alerts/standard-reference", {}, tokens, refresh),
+      ]);
+      setTargets(targetRows);
+      setStandardReference(Array.isArray(referenceRows) ? referenceRows : []);
+
+      if (canManageAlerts) {
+        const defs = await apiFetch("/alerts/definitions", {}, tokens, refresh);
+        setDefinitions(defs);
+      }
+    } catch (e) {
+      setError(String(e.message || e));
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  useEffect(() => {
+    loadAll();
+  }, [canManageAlerts]);
+
+  const targetOptions = useMemo(
+    () => [{ id: "", name: "All targets" }, ...targets.map((t) => ({ id: String(t.id), name: `${t.name} (${t.host}:${t.port})` }))],
+    [targets]
+  );
+
+  const createDefinition = async (e) => {
+    e.preventDefault();
+    setSaving(true);
+    setTestResult("");
+    try {
+      await apiFetch(
+        "/alerts/definitions",
+        {
+          method: "POST",
+          body: JSON.stringify({
+            name: form.name,
+            description: form.description || null,
+            target_id: form.target_id ? Number(form.target_id) : null,
+            sql_text: form.sql_text,
+            comparison: form.comparison,
+            warning_threshold: form.warning_threshold === "" ? null : Number(form.warning_threshold),
+            alert_threshold: Number(form.alert_threshold),
+            enabled: !!form.enabled,
+          }),
+        },
+        tokens,
+        refresh
+      );
+      setForm(initialForm);
+      await loadAll();
+    } catch (e) {
+      setError(String(e.message || e));
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  const testDefinition = async () => {
+    if (!form.target_id) {
+      setTestResult("Select a specific target to test this SQL query.");
+      return;
+    }
+    setTesting(true);
+    setTestResult("");
+    try {
+      const res = await apiFetch(
+        "/alerts/definitions/test",
+        {
+          method: "POST",
+          body: JSON.stringify({
+            target_id: Number(form.target_id),
+            sql_text: form.sql_text,
+          }),
+        },
+        tokens,
+        refresh
+      );
+      if (res.ok) {
+        setTestResult(`Query test succeeded. Returned value: ${formatAlertValue(res.value)}`);
+      } else {
+        setTestResult(`Query test failed: ${res.error}`);
+      }
+    } catch (e) {
+      setTestResult(String(e.message || e));
+    } finally {
+      setTesting(false);
+    }
+  };
+
+  const removeDefinition = async (definitionId) => {
+    if (!confirm("Delete this custom alert definition?")) return;
+    try {
+      await apiFetch(`/alerts/definitions/${definitionId}`, { method: "DELETE" }, tokens, refresh);
+      await loadAll();
+    } catch (e) {
+      setError(String(e.message || e));
+    }
+  };
+
+  const toggleDefinition = async (definition) => {
+    try {
+      await apiFetch(
+        `/alerts/definitions/${definition.id}`,
+        { method: "PUT", body: JSON.stringify({ enabled: !definition.enabled }) },
+        tokens,
+        refresh
+      );
+      await loadAll();
+    } catch (e) {
+      setError(String(e.message || e));
+    }
+  };
+
+  const toggleExpanded = (key) => {
+    setExpandedKey((prev) => (prev === key ? "" : key));
+  };
+
+  useEffect(() => {
+    const params = new URLSearchParams(location.search);
+    const openKey = params.get("open");
+    if (!openKey) return;
+    setExpandedKey(openKey);
+    const id = `alert-item-${openKey.replace(/[^a-zA-Z0-9_-]/g, "-")}`;
+    setTimeout(() => {
+      const el = document.getElementById(id);
+      if (el) el.scrollIntoView({ behavior: "smooth", block: "center" });
+    }, 120);
+  }, [location.search]);
+
+  if (loading) return <div className="card">Loading alerts...</div>;
+
+  return (
+    <div className="alerts-page">
+      <h2>Alerts</h2>
+      <p className="alerts-subtitle">Warnings are early signals. Alerts are critical thresholds reached or exceeded.</p>
+      {error && <div className="card error">{error}</div>}
+
+      <div className="grid two alerts-kpis">
+        <div className="card alerts-kpi warning">
+          <strong>{alertStatus.warning_count || 0}</strong>
+          <span>Warnings</span>
+        </div>
+        <div className="card alerts-kpi alert">
+          <strong>{alertStatus.alert_count || 0}</strong>
+          <span>Alerts</span>
+        </div>
+      </div>
+
+      <div className="grid two">
+        <section className="card">
+          <h3>Warnings</h3>
+          {alertStatus.warnings?.length ? (
+            <div className="alerts-list">
+              {alertStatus.warnings.map((item) => {
+                const isOpen = expandedKey === item.alert_key;
+                const suggestions = buildAlertSuggestions(item);
+                return (
+                  <article
+                    className={`alert-item warning ${isOpen ? "is-open" : ""}`}
+                    key={item.alert_key}
+                    id={`alert-item-${item.alert_key.replace(/[^a-zA-Z0-9_-]/g, "-")}`}
+                    onClick={() => toggleExpanded(item.alert_key)}
+                    role="button"
+                    tabIndex={0}
+                  >
+                    <div className="alert-item-head">
+                      <span className="alert-badge warning">Warning</span>
+                      <strong>{item.name}</strong>
+                      <small>{item.target_name}</small>
+                    </div>
+                    <p>{item.description}</p>
+                    <p className="alert-message">{item.message}</p>
+                    {isOpen && (
+                      <div className="alert-details-grid">
+                        <div><span>Source</span><strong>{item.source}</strong></div>
+                        <div><span>Category</span><strong>{item.category}</strong></div>
+                        <div><span>Current Value</span><strong>{formatAlertValue(item.value)}</strong></div>
+                        <div><span>Comparison</span><strong>{item.comparison}</strong></div>
+                        <div><span>Warning Threshold</span><strong>{formatAlertValue(item.warning_threshold)}</strong></div>
+                        <div><span>Alert Threshold</span><strong>{formatAlertValue(item.alert_threshold)}</strong></div>
+                        <div><span>Checked At</span><strong>{formatTs(item.checked_at)}</strong></div>
+                        <div><span>Target ID</span><strong>{item.target_id}</strong></div>
+                        {item.sql_text && <div className="alert-sql"><code>{item.sql_text}</code></div>}
+                        <div className="alert-suggestions">
+                          <h4>Recommended actions</h4>
+                          <ul>
+                            {suggestions.map((tip, idx) => <li key={idx}>{tip}</li>)}
+                          </ul>
+                        </div>
+                      </div>
+                    )}
+                  </article>
+                );
+              })}
+            </div>
+          ) : (
+            <p className="muted">No warning-level alerts right now.</p>
+          )}
+        </section>
+
+        <section className="card">
+          <h3>Alerts</h3>
+          {alertStatus.alerts?.length ? (
+            <div className="alerts-list">
+              {alertStatus.alerts.map((item) => {
+                const isOpen = expandedKey === item.alert_key;
+                const suggestions = buildAlertSuggestions(item);
+                return (
+                  <article
+                    className={`alert-item alert ${isOpen ? "is-open" : ""}`}
+                    key={item.alert_key}
+                    id={`alert-item-${item.alert_key.replace(/[^a-zA-Z0-9_-]/g, "-")}`}
+                    onClick={() => toggleExpanded(item.alert_key)}
+                    role="button"
+                    tabIndex={0}
+                  >
+                    <div className="alert-item-head">
+                      <span className="alert-badge alert">Alert</span>
+                      <strong>{item.name}</strong>
+                      <small>{item.target_name}</small>
+                    </div>
+                    <p>{item.description}</p>
+                    <p className="alert-message">{item.message}</p>
+                    {isOpen && (
+                      <div className="alert-details-grid">
+                        <div><span>Source</span><strong>{item.source}</strong></div>
+                        <div><span>Category</span><strong>{item.category}</strong></div>
+                        <div><span>Current Value</span><strong>{formatAlertValue(item.value)}</strong></div>
+                        <div><span>Comparison</span><strong>{item.comparison}</strong></div>
+                        <div><span>Warning Threshold</span><strong>{formatAlertValue(item.warning_threshold)}</strong></div>
+                        <div><span>Alert Threshold</span><strong>{formatAlertValue(item.alert_threshold)}</strong></div>
+                        <div><span>Checked At</span><strong>{formatTs(item.checked_at)}</strong></div>
+                        <div><span>Target ID</span><strong>{item.target_id}</strong></div>
+                        {item.sql_text && <div className="alert-sql"><code>{item.sql_text}</code></div>}
+                        <div className="alert-suggestions">
+                          <h4>Recommended actions</h4>
+                          <ul>
+                            {suggestions.map((tip, idx) => <li key={idx}>{tip}</li>)}
+                          </ul>
+                        </div>
+                      </div>
+                    )}
+                  </article>
+                );
+              })}
+            </div>
+          ) : (
+            <p className="muted">No critical alerts right now.</p>
+          )}
+        </section>
+      </div>
+
+      <details className="card collapsible">
+        <summary className="collapse-head">
+          <div>
+            <h3>Standard Alert Reference</h3>
+            <p>What each built-in alert checks and which default thresholds are used.</p>
+          </div>
+          <span className="collapse-chevron" aria-hidden="true">v</span>
+        </summary>
+        <div className="standard-alerts-note">
+          Some rules include traffic guards to reduce noise (for example rollback ratio needs enough transactions).
+        </div>
+        <div className="standard-alerts-table-wrap">
+          <table className="standard-alerts-table">
+            <thead>
+              <tr>
+                <th>Alert</th>
+                <th>Checks</th>
+                <th>Comparison</th>
+                <th>Warning</th>
+                <th>Alert</th>
+              </tr>
+            </thead>
+            <tbody>
+              {standardReference.length > 0 ? (
+                standardReference.map((row) => (
+                  <tr key={row.key || row.name}>
+                    <td>{row.name}</td>
+                    <td>{row.checks}</td>
+                    <td><code>{row.comparison}</code></td>
+                    <td>{row.warning}</td>
+                    <td>{row.alert}</td>
+                  </tr>
+                ))
+              ) : (
+                <tr>
+                  <td colSpan={5} className="muted">No standard alert metadata available.</td>
+                </tr>
+              )}
+            </tbody>
+          </table>
+        </div>
+      </details>
+
+      {canManageAlerts && (
+        <>
+          <details className="card collapsible">
+            <summary className="collapse-head">
+              <div>
+                <h3>Create Custom Alert</h3>
+                <p>Admins and operators can add SQL-based checks with warning and alert thresholds.</p>
+              </div>
+              <span className="collapse-chevron" aria-hidden="true">v</span>
+            </summary>
+            <form className="alert-form grid two" onSubmit={createDefinition}>
+              <div className="field">
+                <label>Name</label>
+                <input value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} placeholder="e.g. High Active Sessions" required />
+              </div>
+              <div className="field">
+                <label>Target Scope</label>
+                <select value={form.target_id} onChange={(e) => setForm({ ...form, target_id: e.target.value })}>
+                  {targetOptions.map((opt) => (
+                    <option key={opt.id || "all"} value={opt.id}>
+                      {opt.name}
+                    </option>
+                  ))}
+                </select>
+              </div>
+              <div className="field">
+                <label>Comparison</label>
+                <select value={form.comparison} onChange={(e) => setForm({ ...form, comparison: e.target.value })}>
+                  <option value="gte">greater than or equal (&gt;=)</option>
+                  <option value="gt">greater than (&gt;)</option>
+                  <option value="lte">less than or equal (&lt;=)</option>
+                  <option value="lt">less than (&lt;)</option>
+                </select>
+              </div>
+              <div className="field">
+                <label>Description</label>
+                <input value={form.description} onChange={(e) => setForm({ ...form, description: e.target.value })} placeholder="What does this check validate?" />
+              </div>
+              <div className="field">
+                <label>Warning Threshold (optional)</label>
+                <input type="number" step="any" value={form.warning_threshold} onChange={(e) => setForm({ ...form, warning_threshold: e.target.value })} placeholder="e.g. 20" />
+              </div>
+              <div className="field">
+                <label>Alert Threshold</label>
+                <input type="number" step="any" value={form.alert_threshold} onChange={(e) => setForm({ ...form, alert_threshold: e.target.value })} placeholder="e.g. 50" required />
+              </div>
+              <div className="field field-full">
+                <label>SQL Query (must return one numeric value)</label>
+                <textarea
+                  rows={4}
+                  value={form.sql_text}
+                  onChange={(e) => setForm({ ...form, sql_text: e.target.value })}
+                  placeholder="SELECT count(*)::float FROM pg_stat_activity WHERE state = 'active'"
+                  required
+                />
+              </div>
+              <div className="alert-form-actions field-full">
+                <button type="button" className="secondary-btn" onClick={testDefinition} disabled={testing}>
+                  {testing ? "Testing..." : "Test query output"}
+                </button>
+                <button className="primary-btn" disabled={saving}>
+                  {saving ? "Creating..." : "Create custom alert"}
+                </button>
+              </div>
+              {testResult && <div className="test-connection-result">{testResult}</div>}
+            </form>
+          </details>
+
+          <details className="card collapsible">
+            <summary className="collapse-head">
+              <div>
+                <h3>Custom Alert Definitions</h3>
+                <p>All saved SQL-based alert rules.</p>
+              </div>
+              <span className="collapse-chevron" aria-hidden="true">v</span>
+            </summary>
+            {definitions.length ? (
+              <table>
+                <thead>
+                  <tr>
+                    <th>Name</th>
+                    <th>Scope</th>
+                    <th>Comparison</th>
+                    <th>Warn</th>
+                    <th>Alert</th>
+                    <th>Status</th>
+                    <th>Actions</th>
+                  </tr>
+                </thead>
+                <tbody>
+                  {definitions.map((d) => (
+                    <tr key={d.id}>
+                      <td>{d.name}</td>
+                      <td>{d.target_id ? targets.find((t) => t.id === d.target_id)?.name || `Target #${d.target_id}` : "All targets"}</td>
+                      <td>{d.comparison}</td>
+                      <td>{d.warning_threshold ?? "-"}</td>
+                      <td>{d.alert_threshold}</td>
+                      <td>{d.enabled ? "Enabled" : "Disabled"}</td>
+                      <td>
+                        <div className="row-actions">
+                          <button type="button" className={`table-action-btn toggle ${d.enabled ? "enabled" : "disabled"}`} onClick={() => toggleDefinition(d)}>
+                            <span aria-hidden="true">
+                              <svg viewBox="0 0 24 24" width="13" height="13">
+                                <path d="M7 12h10M12 7v10" stroke="currentColor" strokeWidth="2" fill="none" strokeLinecap="round" />
+                              </svg>
+                            </span>
+                            {d.enabled ? "Disable" : "Enable"}
+                          </button>
+                          <button type="button" className="table-action-btn delete" onClick={() => removeDefinition(d.id)}>
+                            <span aria-hidden="true">
+                              <svg viewBox="0 0 24 24" width="13" height="13">
+                                <path d="M6 7h12l-1 13H7L6 7zm3-3h6l1 2H8l1-2z" fill="currentColor" />
+                              </svg>
+                            </span>
+                            Delete
+                          </button>
+                        </div>
+                      </td>
+                    </tr>
+                  ))}
+                </tbody>
+              </table>
+            ) : (
+              <p className="muted">No custom alerts created yet.</p>
+            )}
+          </details>
+        </>
+      )}
+    </div>
+  );
+}

frontend/src/pages/DashboardPage.jsx

@@ -3,9 +3,20 @@ import { Link } from "react-router-dom";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
 
+function getTargetGroupMeta(target) {
+  const tags = target?.tags || {};
+  if (tags.monitor_mode !== "all_databases" || !tags.monitor_group_id) return null;
+  return {
+    id: tags.monitor_group_id,
+    name: tags.monitor_group_name || target.name || "All databases",
+  };
+}
+
 export function DashboardPage() {
-  const { tokens, refresh } = useAuth();
+  const { tokens, refresh, alertStatus } = useAuth();
   const [targets, setTargets] = useState([]);
+  const [search, setSearch] = useState("");
+  const [openGroups, setOpenGroups] = useState({});
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState("");
 
@@ -13,8 +24,10 @@ export function DashboardPage() {
     let active = true;
     (async () => {
       try {
-        const data = await apiFetch("/targets", {}, tokens, refresh);
-        if (active) setTargets(data);
+        const targetRows = await apiFetch("/targets", {}, tokens, refresh);
+        if (active) {
+          setTargets(targetRows);
+        }
       } catch (e) {
         if (active) setError(String(e.message || e));
       } finally {
@@ -26,48 +39,172 @@ export function DashboardPage() {
     };
   }, [tokens, refresh]);
 
-  if (loading) return <div className="card">Lade Dashboard...</div>;
+  if (loading) return <div className="card">Loading dashboard...</div>;
   if (error) return <div className="card error">{error}</div>;
 
+  const targetSeverities = new Map();
+  for (const item of alertStatus.warnings || []) {
+    if (!targetSeverities.has(item.target_id)) targetSeverities.set(item.target_id, "warning");
+  }
+  for (const item of alertStatus.alerts || []) {
+    targetSeverities.set(item.target_id, "alert");
+  }
+
+  const affectedTargetCount = targetSeverities.size;
+  const okCount = Math.max(0, targets.length - affectedTargetCount);
+  const filteredTargets = targets.filter((t) => {
+    const q = search.trim().toLowerCase();
+    if (!q) return true;
     return (
-    <div>
+      (t.name || "").toLowerCase().includes(q) ||
+      (t.host || "").toLowerCase().includes(q) ||
+      (t.dbname || "").toLowerCase().includes(q)
+    );
+  });
+  const groupedRows = [];
+  const groupedMap = new Map();
+  for (const t of filteredTargets) {
+    const meta = getTargetGroupMeta(t);
+    if (!meta) {
+      groupedRows.push({ type: "single", target: t });
+      continue;
+    }
+    if (!groupedMap.has(meta.id)) {
+      const groupRow = { type: "group", groupId: meta.id, groupName: meta.name, targets: [] };
+      groupedMap.set(meta.id, groupRow);
+      groupedRows.push(groupRow);
+    }
+    groupedMap.get(meta.id).targets.push(t);
+  }
+
+  return (
+    <div className="dashboard-page">
       <h2>Dashboard Overview</h2>
-      <div className="grid three">
-        <div className="card stat">
+      <p className="dashboard-subtitle">Real-time snapshot of monitored PostgreSQL targets.</p>
+      <div className="dashboard-kpis-grid">
+        <div className="card stat kpi-card">
+          <div className="kpi-orb blue" />
           <strong>{targets.length}</strong>
-          <span>Targets</span>
+          <span className="kpi-label">Total Targets</span>
         </div>
-        <div className="card stat">
-          <strong>{targets.length}</strong>
-          <span>Status OK (placeholder)</span>
+        <div className="card stat kpi-card ok">
+          <div className="kpi-orb green" />
+          <strong>{okCount}</strong>
+          <span className="kpi-label">Status OK</span>
         </div>
-        <div className="card stat">
-          <strong>0</strong>
-          <span>Alerts (placeholder)</span>
+        <div className="card stat kpi-card warning">
+          <div className="kpi-orb amber" />
+          <strong>{alertStatus.warning_count || 0}</strong>
+          <span className="kpi-label">Warnings</span>
+        </div>
+        <div className="card stat kpi-card alert">
+          <div className="kpi-orb red" />
+          <strong>{alertStatus.alert_count || 0}</strong>
+          <span className="kpi-label">Alerts</span>
         </div>
       </div>
-      <div className="card">
+
+      <div className="card dashboard-targets-card">
+        <div className="dashboard-targets-head">
+          <div>
             <h3>Targets</h3>
-        <table>
-          <thead>
-            <tr>
-              <th>Name</th>
-              <th>Host</th>
-              <th>DB</th>
-              <th>Aktion</th>
-            </tr>
-          </thead>
-          <tbody>
-            {targets.map((t) => (
-              <tr key={t.id}>
-                <td>{t.name}</td>
-                <td>{t.host}:{t.port}</td>
-                <td>{t.dbname}</td>
-                <td><Link to={`/targets/${t.id}`}>Details</Link></td>
-              </tr>
-            ))}
-          </tbody>
-        </table>
+            <span>{filteredTargets.length} shown of {targets.length} registered</span>
+          </div>
+          <div className="dashboard-target-search">
+            <input
+              value={search}
+              onChange={(e) => setSearch(e.target.value)}
+              placeholder="Search by name, host, or database..."
+            />
+          </div>
+        </div>
+
+        <div className="dashboard-target-list">
+          {groupedRows.map((row) => {
+            if (row.type === "single") {
+              const t = row.target;
+              const severity = targetSeverities.get(t.id) || "ok";
+              return (
+                <article className="dashboard-target-card" key={`single-${t.id}`}>
+                  <div className="target-main">
+                    <div className="target-title-row">
+                      <h4>{t.name}</h4>
+                      <span className={`status-chip ${severity}`}>
+                        {severity === "alert" ? "Alert" : severity === "warning" ? "Warning" : "OK"}
+                      </span>
+                    </div>
+                    <p><strong>Host:</strong> {t.host}:{t.port}</p>
+                    <p><strong>DB:</strong> {t.dbname}</p>
+                  </div>
+                  <div className="target-actions">
+                    <Link className="table-action-btn details" to={`/targets/${t.id}`}>
+                      <span aria-hidden="true">
+                        <svg viewBox="0 0 24 24" width="13" height="13">
+                          <path d="M2 12s3.5-6 10-6 10 6 10 6-3.5 6-10 6-10-6-10-6zm10 3a3 3 0 1 0 0-6 3 3 0 0 0 0 6z" fill="currentColor" />
+                        </svg>
+                      </span>
+                      Details
+                    </Link>
+                  </div>
+                </article>
+              );
+            }
+
+            const highestSeverity = row.targets.some((t) => targetSeverities.get(t.id) === "alert")
+              ? "alert"
+              : row.targets.some((t) => targetSeverities.get(t.id) === "warning")
+                ? "warning"
+                : "ok";
+            const first = row.targets[0];
+            const isOpen = !!openGroups[row.groupId];
+            return (
+              <article className="dashboard-target-card dashboard-target-group" key={`group-${row.groupId}`}>
+                <div className="target-main">
+                  <div className="target-title-row">
+                    <h4>{row.groupName}</h4>
+                    <span className={`status-chip ${highestSeverity}`}>
+                      {highestSeverity === "alert" ? "Alert" : highestSeverity === "warning" ? "Warning" : "OK"}
+                    </span>
+                  </div>
+                  <p><strong>Host:</strong> {first.host}:{first.port}</p>
+                  <p><strong>DB:</strong> All databases ({row.targets.length})</p>
+                </div>
+                <div className="target-actions">
+                  <button
+                    type="button"
+                    className="table-action-btn edit"
+                    onClick={() => setOpenGroups((prev) => ({ ...prev, [row.groupId]: !prev[row.groupId] }))}
+                  >
+                    {isOpen ? "Hide DBs" : "Show DBs"}
+                  </button>
+                </div>
+                {isOpen && (
+                  <div className="dashboard-group-list">
+                    {row.targets.map((t) => {
+                      const severity = targetSeverities.get(t.id) || "ok";
+                      return (
+                        <div key={`child-${t.id}`} className="dashboard-group-item">
+                          <div>
+                            <strong>{t.dbname}</strong>
+                            <span className={`status-chip ${severity}`}>
+                              {severity === "alert" ? "Alert" : severity === "warning" ? "Warning" : "OK"}
+                            </span>
+                          </div>
+                          <Link className="table-action-btn details small-btn" to={`/targets/${t.id}`}>
+                            Details
+                          </Link>
+                        </div>
+                      );
+                    })}
+                  </div>
+                )}
+              </article>
+            );
+          })}
+          {filteredTargets.length === 0 && (
+            <div className="dashboard-empty">No targets match your search.</div>
+          )}
+        </div>
       </div>
     </div>
   );

frontend/src/pages/LoginPage.jsx

@@ -18,7 +18,7 @@ export function LoginPage() {
       await login(email, password);
       navigate("/");
     } catch {
-      setError("Login fehlgeschlagen");
+      setError("Login failed");
     } finally {
       setLoading(false);
     }
@@ -27,13 +27,16 @@ export function LoginPage() {
   return (
     <div className="login-wrap">
       <form className="card login-card" onSubmit={submit}>
+        <div className="login-logo-wrap" aria-hidden="true">
+          <img src="/nexapg-logo.svg" alt="NexaPG" className="login-logo" />
+        </div>
         <div className="login-eyebrow">NexaPG Monitor</div>
-        <h2>Willkommen zurück</h2>
-        <p className="login-subtitle">Melde dich an, um Monitoring und Query Insights zu öffnen.</p>
+        <h2>Welcome back</h2>
+        <p className="login-subtitle">Sign in to access monitoring and query insights.</p>
         <div className="input-shell">
           <input
             type="email"
-            placeholder="E-Mail"
+            placeholder="Email"
             value={email}
             onChange={(e) => setEmail(e.target.value)}
             autoComplete="username"
@@ -49,7 +52,7 @@ export function LoginPage() {
           />
         </div>
         {error && <p className="error">{error}</p>}
-        <button className="login-cta" disabled={loading}>{loading ? "Bitte warten..." : "Einloggen"}</button>
+        <button className="login-cta" disabled={loading}>{loading ? "Please wait..." : "Sign in"}</button>
       </form>
     </div>
   );

frontend/src/pages/QueryInsightsPage.jsx

@@ -1,46 +1,165 @@
-import React, { useEffect, useState } from "react";
+import React, { useEffect, useRef, useState } from "react";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
 
+const PAGE_SIZE = 10;
+
+function scoreQuery(row) {
+  const mean = Number(row.mean_time || 0);
+  const calls = Number(row.calls || 0);
+  const total = Number(row.total_time || 0);
+  const rows = Number(row.rows || 0);
+  return mean * 1.4 + total * 0.9 + calls * 0.2 + Math.min(rows / 50, 25);
+}
+
+function classifyQuery(row) {
+  if ((row.mean_time || 0) > 100) return { label: "Very Slow", kind: "danger" };
+  if ((row.total_time || 0) > 250) return { label: "Heavy", kind: "warn" };
+  if ((row.calls || 0) > 500) return { label: "Frequent", kind: "info" };
+  return { label: "Normal", kind: "ok" };
+}
+
+function compactSql(sql) {
+  if (!sql) return "-";
+  return sql.replace(/\s+/g, " ").trim();
+}
+
+function buildQueryTips(row) {
+  if (!row) return [];
+  const tips = [];
+  const sql = (row.query_text || "").toLowerCase();
+
+  if ((row.mean_time || 0) > 100) {
+    tips.push("High latency per call: inspect execution plan with EXPLAIN (ANALYZE, BUFFERS).");
+  }
+  if ((row.total_time || 0) > 500) {
+    tips.push("High cumulative runtime: optimize this query first for fastest overall impact.");
+  }
+  if ((row.calls || 0) > 500) {
+    tips.push("Very frequent query: consider caching or reducing call frequency in application code.");
+  }
+  if ((row.rows || 0) > 100000) {
+    tips.push("Large row output: return fewer columns/rows or add pagination at query/API layer.");
+  }
+  if (/select\s+\*/.test(sql)) {
+    tips.push("Avoid SELECT *: request only required columns to reduce IO and transfer cost.");
+  }
+  if (/order\s+by/.test(sql) && !/limit\s+\d+/.test(sql)) {
+    tips.push("ORDER BY without LIMIT can be expensive: add LIMIT where possible.");
+  }
+  if (/where/.test(sql) && / from /.test(sql)) {
+    tips.push("Filter query detected: verify indexes exist on WHERE / JOIN columns.");
+  }
+  if (/like\s+'%/.test(sql)) {
+    tips.push("Leading wildcard LIKE can bypass indexes: consider trigram index (pg_trgm).");
+  }
+  if (tips.length === 0) {
+    tips.push("No obvious anti-pattern detected. Validate with EXPLAIN and index usage statistics.");
+  }
+
+  return tips.slice(0, 5);
+}
+
 export function QueryInsightsPage() {
   const { tokens, refresh } = useAuth();
+  const refreshRef = useRef(refresh);
   const [targets, setTargets] = useState([]);
   const [targetId, setTargetId] = useState("");
   const [rows, setRows] = useState([]);
+  const [selectedQuery, setSelectedQuery] = useState(null);
+  const [search, setSearch] = useState("");
+  const [page, setPage] = useState(1);
   const [error, setError] = useState("");
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    refreshRef.current = refresh;
+  }, [refresh]);
 
   useEffect(() => {
     (async () => {
       try {
         const t = await apiFetch("/targets", {}, tokens, refresh);
-        setTargets(t);
-        if (t.length > 0) setTargetId(String(t[0].id));
+        const supported = t.filter((item) => item.use_pg_stat_statements !== false);
+        setTargets(supported);
+        if (supported.length > 0) setTargetId(String(supported[0].id));
+        else setTargetId("");
       } catch (e) {
         setError(String(e.message || e));
+      } finally {
+        setLoading(false);
       }
     })();
   }, []);
 
   useEffect(() => {
     if (!targetId) return;
+    let active = true;
     (async () => {
       try {
-        const data = await apiFetch(`/targets/${targetId}/top-queries`, {}, tokens, refresh);
+        const data = await apiFetch(`/targets/${targetId}/top-queries`, {}, tokens, refreshRef.current);
+        if (!active) return;
         setRows(data);
+        setSelectedQuery((prev) => {
+          if (!prev) return data[0] || null;
+          const keep = data.find((row) => row.queryid === prev.queryid);
+          return keep || data[0] || null;
+        });
+        setPage((prev) => (prev === 1 ? prev : 1));
       } catch (e) {
-        setError(String(e.message || e));
+        if (active) setError(String(e.message || e));
       }
     })();
-  }, [targetId, tokens, refresh]);
+    return () => {
+      active = false;
+    };
+  }, [targetId, tokens?.accessToken, tokens?.refreshToken]);
+
+  const dedupedByQueryId = [...rows].reduce((acc, row) => {
+    if (!row?.queryid) return acc;
+    if (!acc[row.queryid]) acc[row.queryid] = row;
+    return acc;
+  }, {});
+  const uniqueRows = Object.values(dedupedByQueryId);
+
+  const sorted = [...uniqueRows].sort((a, b) => (b.total_time || 0) - (a.total_time || 0));
+  const byMean = [...uniqueRows].sort((a, b) => (b.mean_time || 0) - (a.mean_time || 0));
+  const byCalls = [...uniqueRows].sort((a, b) => (b.calls || 0) - (a.calls || 0));
+  const byRows = [...uniqueRows].sort((a, b) => (b.rows || 0) - (a.rows || 0));
+  const byPriority = [...uniqueRows].sort((a, b) => scoreQuery(b) - scoreQuery(a));
+
+  const filtered = byPriority.filter((r) => {
+    if (!search.trim()) return true;
+    return compactSql(r.query_text).toLowerCase().includes(search.toLowerCase());
+  });
+  const totalPages = Math.max(1, Math.ceil(filtered.length / PAGE_SIZE));
+  const safePage = Math.min(page, totalPages);
+  const paged = filtered.slice((safePage - 1) * PAGE_SIZE, safePage * PAGE_SIZE);
+  const selectedTips = buildQueryTips(selectedQuery);
+
+  const categories = [
+    { key: "priority", title: "Optimization Priority", row: byPriority[0], subtitle: "Best first candidate to optimize" },
+    { key: "total", title: "Longest Total Time", row: sorted[0], subtitle: "Biggest cumulative runtime impact" },
+    { key: "mean", title: "Highest Mean Time", row: byMean[0], subtitle: "Slowest single-call latency" },
+    { key: "calls", title: "Most Frequent", row: byCalls[0], subtitle: "Executed very often" },
+    { key: "rows", title: "Most Rows Returned", row: byRows[0], subtitle: "Potentially heavy scans" },
+  ];
 
   return (
-    <div>
+    <div className="query-insights-page">
       <h2>Query Insights</h2>
-      <p>Hinweis: Benötigt aktivierte Extension <code>pg_stat_statements</code> auf dem Zielsystem.</p>
-      {error && <div className="card error">{error}</div>}
+      <p>Note: This section requires the <code>pg_stat_statements</code> extension on the monitored target.</p>
+      {targets.length === 0 && !loading && (
         <div className="card">
-        <label>Target </label>
-        <select value={targetId} onChange={(e) => setTargetId(e.target.value)}>
+          No targets with enabled <code>pg_stat_statements</code> are available.
+          Enable it in <strong>Targets Management</strong> for a target to use Query Insights.
+        </div>
+      )}
+      {error && <div className="card error">{error}</div>}
+      <div className="card query-toolbar">
+        <div className="field">
+          <label>Target</label>
+          <select value={targetId} onChange={(e) => setTargetId(e.target.value)} disabled={!targets.length}>
             {targets.map((t) => (
               <option key={t.id} value={t.id}>
                 {t.name}
@@ -48,32 +167,141 @@ export function QueryInsightsPage() {
             ))}
           </select>
         </div>
-      <div className="card">
+        <div className="field">
+          <label>Search Query Text</label>
+          <input
+            value={search}
+            onChange={(e) => {
+              setSearch(e.target.value);
+              setPage(1);
+            }}
+            placeholder="e.g. select * from users"
+          />
+        </div>
+      </div>
+
+      {loading ? (
+        <div className="card">Loading query insights...</div>
+      ) : (
+        <>
+          <div className="grid three">
+            {categories.map((item) => {
+              const r = item.row;
+              const state = r ? classifyQuery(r) : null;
+              return (
+                <div
+                  className="card query-category"
+                  key={item.key}
+                  onClick={() => r && setSelectedQuery(r)}
+                  role="button"
+                  tabIndex={0}
+                >
+                  <h4>{item.title}</h4>
+                  <small>{item.subtitle}</small>
+                  {r ? (
+                    <>
+                      <div className={`query-state ${state.kind}`}>{state.label}</div>
+                      <div className="query-kpi">
+                        <span>Total</span>
+                        <strong>{Number(r.total_time || 0).toFixed(2)} ms</strong>
+                      </div>
+                      <div className="query-kpi">
+                        <span>Mean</span>
+                        <strong>{Number(r.mean_time || 0).toFixed(2)} ms</strong>
+                      </div>
+                      <div className="query-kpi">
+                        <span>Calls</span>
+                        <strong>{r.calls}</strong>
+                      </div>
+                    </>
+                  ) : (
+                    <p>No data</p>
+                  )}
+                </div>
+              );
+            })}
+          </div>
+
+          <div className="grid two">
+            <div className="card query-list">
+              <h3>Ranked Queries</h3>
               <table>
                 <thead>
                   <tr>
-              <th>Time</th>
+                    <th>Priority</th>
                     <th>Calls</th>
                     <th>Total ms</th>
                     <th>Mean ms</th>
                     <th>Rows</th>
-              <th>Query</th>
+                    <th>Query Preview</th>
                   </tr>
                 </thead>
                 <tbody>
-            {rows.map((r, i) => (
-              <tr key={i}>
-                <td>{new Date(r.ts).toLocaleString()}</td>
+                  {paged.map((r, i) => {
+                    const state = classifyQuery(r);
+                    return (
+                      <tr key={`${r.queryid}-${i}-${safePage}`} className={selectedQuery?.queryid === r.queryid ? "active-row" : ""}>
+                        <td><span className={`query-state ${state.kind}`}>{state.label}</span></td>
                         <td>{r.calls}</td>
-                <td>{r.total_time.toFixed(2)}</td>
-                <td>{r.mean_time.toFixed(2)}</td>
+                        <td>{Number(r.total_time || 0).toFixed(2)}</td>
+                        <td>{Number(r.mean_time || 0).toFixed(2)}</td>
                         <td>{r.rows}</td>
-                <td className="query">{r.query_text || "-"}</td>
+                        <td className="query">
+                          <button className="table-link" onClick={() => setSelectedQuery(r)}>
+                            {compactSql(r.query_text)}
+                          </button>
+                        </td>
                       </tr>
-            ))}
+                    );
+                  })}
                 </tbody>
               </table>
+              <div className="pagination">
+                <span className="pagination-info">
+                  Showing {paged.length} of {filtered.length} queries
+                </span>
+                <div className="pagination-actions">
+                  <button type="button" disabled={safePage <= 1} onClick={() => setPage((p) => Math.max(1, p - 1))}>
+                    Prev
+                  </button>
+                  <span>Page {safePage} / {totalPages}</span>
+                  <button type="button" disabled={safePage >= totalPages} onClick={() => setPage((p) => Math.min(totalPages, p + 1))}>
+                    Next
+                  </button>
                 </div>
               </div>
+            </div>
+
+            <div className="card query-detail">
+              <h3>Selected Query</h3>
+              {selectedQuery ? (
+                <>
+                  <div className="overview-metrics">
+                    <div><span>Calls</span><strong>{selectedQuery.calls}</strong></div>
+                    <div><span>Total Time</span><strong>{Number(selectedQuery.total_time || 0).toFixed(2)} ms</strong></div>
+                    <div><span>Mean Time</span><strong>{Number(selectedQuery.mean_time || 0).toFixed(2)} ms</strong></div>
+                    <div><span>Rows</span><strong>{selectedQuery.rows}</strong></div>
+                  </div>
+                  <div className="sql-block">
+                    <code>{selectedQuery.query_text || "-- no query text available --"}</code>
+                  </div>
+                  <div className="query-tips">
+                    <h4>Optimization Suggestions</h4>
+                    <ul>
+                      {selectedTips.map((tip, idx) => <li key={idx}>{tip}</li>)}
+                    </ul>
+                  </div>
+                  <p className="query-hint">
+                    Tip: focus first on queries with high <strong>Total Time</strong> (overall impact) and high <strong>Mean Time</strong> (latency hotspots).
+                  </p>
+                </>
+              ) : (
+                <p>No query selected.</p>
+              )}
+            </div>
+          </div>
+        </>
+      )}
+    </div>
   );
 }

frontend/src/pages/ServiceInfoPage.jsx

@@ -0,0 +1,146 @@
+import React, { useEffect, useState } from "react";
+import { apiFetch } from "../api";
+import { useAuth } from "../state";
+
+function formatUptime(seconds) {
+  const total = Math.max(0, Number(seconds || 0));
+  const d = Math.floor(total / 86400);
+  const h = Math.floor((total % 86400) / 3600);
+  const m = Math.floor((total % 3600) / 60);
+  const s = total % 60;
+  if (d > 0) return `${d}d ${h}h ${m}m`;
+  if (h > 0) return `${h}h ${m}m ${s}s`;
+  return `${m}m ${s}s`;
+}
+
+export function ServiceInfoPage() {
+  const { tokens, refresh, serviceInfo } = useAuth();
+  const [info, setInfo] = useState(null);
+  const [message, setMessage] = useState("");
+  const [error, setError] = useState("");
+  const [busy, setBusy] = useState(false);
+
+  const load = async () => {
+    setError("");
+    const data = await apiFetch("/service/info", {}, tokens, refresh);
+    setInfo(data);
+  };
+
+  useEffect(() => {
+    load().catch((e) => setError(String(e.message || e)));
+  }, []);
+
+  useEffect(() => {
+    if (serviceInfo) setInfo(serviceInfo);
+  }, [serviceInfo]);
+
+  const checkNow = async () => {
+    try {
+      setBusy(true);
+      setError("");
+      setMessage("");
+      const result = await apiFetch("/service/info/check", { method: "POST" }, tokens, refresh);
+      await load();
+      if (result.last_check_error) {
+        setMessage(`Version check finished with warning: ${result.last_check_error}`);
+      } else if (result.update_available) {
+        setMessage(`Update available: ${result.latest_version}`);
+      } else {
+        setMessage("Version check completed. No update detected.");
+      }
+    } catch (e) {
+      setError(String(e.message || e));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  if (!info) {
+    return <div className="card">Loading service information...</div>;
+  }
+
+  return (
+    <div className="service-page">
+      <h2>Service Information</h2>
+      <p className="muted">Runtime details, installed version, and update check status for this NexaPG instance.</p>
+      {error && <div className="card error">{error}</div>}
+      {message && <div className="test-connection-result ok service-msg">{message}</div>}
+
+      <div className={`card service-hero ${info.update_available ? "update" : "ok"}`}>
+        <div>
+          <strong className="service-hero-title">
+            {info.update_available ? `Update available: ${info.latest_version}` : "Service is up to date"}
+          </strong>
+          <p className="muted service-hero-sub">
+            Automatic release checks run every 30 seconds. Source: official NexaPG upstream releases.
+          </p>
+        </div>
+        <button type="button" className="secondary-btn" disabled={busy} onClick={checkNow}>
+          Check Now
+        </button>
+      </div>
+
+      <div className="grid three">
+        <div className="card service-card">
+          <h3>Application</h3>
+          <div className="overview-kv">
+            <span>App Name</span>
+            <strong>{info.app_name}</strong>
+            <span>Environment</span>
+            <strong>{info.environment}</strong>
+            <span>API Prefix</span>
+            <strong>{info.api_prefix}</strong>
+          </div>
+        </div>
+        <div className="card service-card">
+          <h3>Runtime</h3>
+          <div className="overview-kv">
+            <span>Host</span>
+            <strong>{info.hostname}</strong>
+            <span>Python</span>
+            <strong>{info.python_version}</strong>
+            <span>Uptime</span>
+            <strong>{formatUptime(info.uptime_seconds)}</strong>
+          </div>
+        </div>
+        <div className="card service-card">
+          <h3>Version Status</h3>
+          <div className="overview-kv">
+            <span>Current NexaPG Version</span>
+            <strong>{info.app_version}</strong>
+            <span>Latest Known Version</span>
+            <strong>{info.latest_version || "-"}</strong>
+            <span>Update Status</span>
+            <strong className={info.update_available ? "service-status-update" : "service-status-ok"}>
+              {info.update_available ? "Update available" : "Up to date"}
+            </strong>
+            <span>Last Check</span>
+            <strong>{info.last_checked_at ? new Date(info.last_checked_at).toLocaleString() : "never"}</strong>
+          </div>
+        </div>
+      </div>
+
+      <div className="card service-card">
+        <h3>Release Source</h3>
+        <p className="muted">
+          Update checks run against the official NexaPG repository. This source is fixed in code and cannot be changed
+          via UI.
+        </p>
+        <div className="overview-kv">
+          <span>Source Repository</span>
+          <strong>{info.update_source}</strong>
+          <span>Latest Reference Type</span>
+          <strong>{info.latest_ref || "-"}</strong>
+        </div>
+      </div>
+
+      <div className="card service-card">
+        <h3>Version Control Policy</h3>
+        <p className="muted">
+          Version and update-source settings are not editable in the app. Only code maintainers of the official NexaPG
+          repository can change that behavior.
+        </p>
+      </div>
+    </div>
+  );
+}

frontend/src/pages/TargetDetailPage.jsx

@@ -1,5 +1,5 @@
-import React, { useEffect, useMemo, useState } from "react";
-import { useParams } from "react-router-dom";
+import React, { useEffect, useMemo, useRef, useState } from "react";
+import { useNavigate, useParams } from "react-router-dom";
 import { Line, LineChart, ResponsiveContainer, Tooltip, XAxis, YAxis } from "recharts";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
@@ -41,6 +41,19 @@ function formatNumber(value, digits = 2) {
   return Number(value).toFixed(digits);
 }
 
+function formatHostMetricUnavailable() {
+  return "N/A (agentless)";
+}
+
+function formatDiskSpaceAgentless(diskSpace) {
+  if (!diskSpace) return formatHostMetricUnavailable();
+  if (diskSpace.free_bytes !== null && diskSpace.free_bytes !== undefined) {
+    return formatBytes(diskSpace.free_bytes);
+  }
+  if (diskSpace.status === "unavailable") return formatHostMetricUnavailable();
+  return "-";
+}
+
 function MetricsTooltip({ active, payload, label }) {
   if (!active || !payload || payload.length === 0) return null;
   const row = payload[0]?.payload || {};
@@ -54,6 +67,19 @@ function MetricsTooltip({ active, payload, label }) {
   );
 }
 
+function didMetricSeriesChange(prev = [], next = []) {
+  if (!Array.isArray(prev) || !Array.isArray(next)) return true;
+  if (prev.length !== next.length) return true;
+  if (prev.length === 0 && next.length === 0) return false;
+  const prevLast = prev[prev.length - 1];
+  const nextLast = next[next.length - 1];
+  return prevLast?.ts !== nextLast?.ts || Number(prevLast?.value) !== Number(nextLast?.value);
+}
+
+function isTargetUnreachableError(err) {
+  return err?.code === "target_unreachable" || err?.status === 503;
+}
+
 async function loadMetric(targetId, metric, range, tokens, refresh) {
   const { from, to } = toQueryRange(range);
   return apiFetch(
@@ -66,47 +92,125 @@ async function loadMetric(targetId, metric, range, tokens, refresh) {
 
 export function TargetDetailPage() {
   const { id } = useParams();
-  const { tokens, refresh } = useAuth();
+  const navigate = useNavigate();
+  const { tokens, refresh, uiMode } = useAuth();
   const [range, setRange] = useState("1h");
+  const [liveMode, setLiveMode] = useState(false);
   const [series, setSeries] = useState({});
   const [locks, setLocks] = useState([]);
   const [activity, setActivity] = useState([]);
   const [overview, setOverview] = useState(null);
   const [targetMeta, setTargetMeta] = useState(null);
+  const [owners, setOwners] = useState([]);
+  const [groupTargets, setGroupTargets] = useState([]);
+  const [offlineState, setOfflineState] = useState(null);
   const [error, setError] = useState("");
   const [loading, setLoading] = useState(true);
+  const refreshRef = useRef(refresh);
+
+  useEffect(() => {
+    refreshRef.current = refresh;
+  }, [refresh]);
 
   useEffect(() => {
     let active = true;
-    (async () => {
+    const loadAll = async () => {
+      if (!series.connections?.length) {
         setLoading(true);
+      }
       try {
-        const [connections, xacts, cache, locksTable, activityTable, overviewData, targetInfo] = await Promise.all([
-          loadMetric(id, "connections_total", range, tokens, refresh),
-          loadMetric(id, "xacts_total", range, tokens, refresh),
-          loadMetric(id, "cache_hit_ratio", range, tokens, refresh),
-          apiFetch(`/targets/${id}/locks`, {}, tokens, refresh),
-          apiFetch(`/targets/${id}/activity`, {}, tokens, refresh),
-          apiFetch(`/targets/${id}/overview`, {}, tokens, refresh),
-          apiFetch(`/targets/${id}`, {}, tokens, refresh),
+        const [connections, xacts, cache, targetInfo, ownerRows, allTargets] = await Promise.all([
+          loadMetric(id, "connections_total", range, tokens, refreshRef.current),
+          loadMetric(id, "xacts_total", range, tokens, refreshRef.current),
+          loadMetric(id, "cache_hit_ratio", range, tokens, refreshRef.current),
+          apiFetch(`/targets/${id}`, {}, tokens, refreshRef.current),
+          apiFetch(`/targets/${id}/owners`, {}, tokens, refreshRef.current),
+          apiFetch("/targets", {}, tokens, refreshRef.current),
         ]);
         if (!active) return;
         setSeries({ connections, xacts, cache });
+        setTargetMeta(targetInfo);
+        setOwners(ownerRows);
+        const groupId = targetInfo?.tags?.monitor_group_id;
+        if (groupId) {
+          const sameGroup = allTargets
+            .filter((item) => item?.tags?.monitor_group_id === groupId)
+            .sort((a, b) => (a.dbname || "").localeCompare(b.dbname || ""));
+          setGroupTargets(sameGroup);
+        } else {
+          setGroupTargets([]);
+        }
+        try {
+          const [locksTable, activityTable, overviewData] = await Promise.all([
+            apiFetch(`/targets/${id}/locks`, {}, tokens, refreshRef.current),
+            apiFetch(`/targets/${id}/activity`, {}, tokens, refreshRef.current),
+            apiFetch(`/targets/${id}/overview`, {}, tokens, refreshRef.current),
+          ]);
+          if (!active) return;
           setLocks(locksTable);
           setActivity(activityTable);
           setOverview(overviewData);
-        setTargetMeta(targetInfo);
+          setOfflineState(null);
+        } catch (liveErr) {
+          if (!active) return;
+          if (isTargetUnreachableError(liveErr)) {
+            setLocks([]);
+            setActivity([]);
+            setOverview(null);
+            setOfflineState({
+              message:
+                "Target is currently unreachable. Check host/port, network route, SSL mode, and database availability.",
+              host: liveErr?.details?.host || targetInfo?.host || "-",
+              port: liveErr?.details?.port || targetInfo?.port || "-",
+              requestId: liveErr?.requestId || null,
+            });
+          } else {
+            throw liveErr;
+          }
+        }
         setError("");
       } catch (e) {
         if (active) setError(String(e.message || e));
       } finally {
         if (active) setLoading(false);
       }
-    })();
+    };
+
+    loadAll();
     return () => {
       active = false;
     };
-  }, [id, range, tokens, refresh]);
+  }, [id, range, tokens?.accessToken, tokens?.refreshToken]);
+
+  useEffect(() => {
+    if (!liveMode) return;
+    let active = true;
+    const intervalId = setInterval(async () => {
+      try {
+        const [connections, xacts, cache] = await Promise.all([
+          loadMetric(id, "connections_total", "15m", tokens, refreshRef.current),
+          loadMetric(id, "xacts_total", "15m", tokens, refreshRef.current),
+          loadMetric(id, "cache_hit_ratio", "15m", tokens, refreshRef.current),
+        ]);
+        if (!active) return;
+        const nextSeries = { connections, xacts, cache };
+        setSeries((prev) => {
+          const changed =
+            didMetricSeriesChange(prev.connections, nextSeries.connections) ||
+            didMetricSeriesChange(prev.xacts, nextSeries.xacts) ||
+            didMetricSeriesChange(prev.cache, nextSeries.cache);
+          return changed ? nextSeries : prev;
+        });
+      } catch {
+        // Keep previous chart values if a live tick fails.
+      }
+    }, 3000);
+
+    return () => {
+      active = false;
+      clearInterval(intervalId);
+    };
+  }, [liveMode, id, tokens?.accessToken, tokens?.refreshToken]);
 
   const chartData = useMemo(
     () => {
@@ -135,7 +239,39 @@ export function TargetDetailPage() {
     [series]
   );
 
-  if (loading) return <div className="card">Lade Target Detail...</div>;
+  const easySummary = useMemo(() => {
+    if (!overview) return null;
+    const latest = chartData[chartData.length - 1];
+    const issues = [];
+    const warnings = [];
+
+    if (overview.partial_failures?.length > 0) warnings.push("Some advanced metrics are currently unavailable.");
+    if ((overview.performance?.deadlocks || 0) > 0) issues.push("Deadlocks were detected.");
+    if ((overview.replication?.mode === "standby") && (overview.replication?.replay_lag_seconds || 0) > 5) {
+      issues.push("Replication lag is above 5 seconds.");
+    }
+    if ((latest?.cache || 0) > 0 && latest.cache < 90) warnings.push("Cache hit ratio is below 90%.");
+    if ((latest?.connections || 0) > 120) warnings.push("Connection count is relatively high.");
+    if ((locks?.length || 0) > 150) warnings.push("High number of active locks.");
+
+    const health = issues.length > 0 ? "problem" : warnings.length > 0 ? "warning" : "ok";
+    const message =
+      health === "ok"
+        ? "Everything looks healthy. No major risks detected right now."
+        : health === "warning"
+          ? "System is operational, but there are signals you should watch."
+          : "Attention required. Critical signals need investigation.";
+
+    return {
+      health,
+      message,
+      issues,
+      warnings,
+      latest,
+    };
+  }, [overview, chartData, locks]);
+
+  if (loading) return <div className="card">Loading target detail...</div>;
   if (error) return <div className="card error">{error}</div>;
 
   const role = overview?.instance?.role || "-";
@@ -148,16 +284,129 @@ export function TargetDetailPage() {
         Target Detail {targetMeta?.name || `#${id}`}
         {targetMeta?.dbname ? ` (${targetMeta.dbname})` : ""}
       </h2>
-      {overview && (
+      {groupTargets.length > 1 && (
+        <div className="field target-db-switcher">
+          <label>Database in this target group</label>
+          <select
+            value={String(id)}
+            onChange={(e) => {
+              const targetId = e.target.value;
+              if (targetId && String(targetId) !== String(id)) {
+                navigate(`/targets/${targetId}`);
+              }
+            }}
+          >
+            {groupTargets.map((item) => (
+              <option key={item.id} value={item.id}>
+                {item.dbname} ({item.name})
+              </option>
+            ))}
+          </select>
+        </div>
+      )}
+      <div className="owner-row">
+        <span className="muted">Responsible users:</span>
+        {owners.length > 0 ? owners.map((item) => <span key={item.user_id} className="owner-pill">{item.email}</span>) : <span className="muted">none assigned</span>}
+      </div>
+      {offlineState && (
+        <div className="card target-offline-card">
+          <h3>Target Offline</h3>
+          <p>{offlineState.message}</p>
+          <div className="target-offline-meta">
+            <span><strong>Host:</strong> {offlineState.host}</span>
+            <span><strong>Port:</strong> {offlineState.port}</span>
+            {offlineState.requestId ? <span><strong>Request ID:</strong> {offlineState.requestId}</span> : null}
+          </div>
+        </div>
+      )}
+      {uiMode === "easy" && overview && easySummary && (
+        <>
+          <div className={`card easy-status ${easySummary.health}`}>
+            <h3>System Health</h3>
+            <p>{easySummary.message}</p>
+            <div className="easy-badge-row">
+              <span className={`easy-badge ${easySummary.health}`}>
+                {easySummary.health === "ok" ? "OK" : easySummary.health === "warning" ? "Warning" : "Problem"}
+              </span>
+            </div>
+          </div>
+
+          <div className="grid three">
+            <div className="card stat">
+              <strong>{formatNumber(easySummary.latest?.connections, 0)}</strong>
+              <span>Current Connections</span>
+            </div>
+            <div className="card stat">
+              <strong>{formatNumber(easySummary.latest?.tps, 2)}</strong>
+              <span>Transactions/sec (approx)</span>
+            </div>
+            <div className="card stat">
+              <strong>{formatNumber(easySummary.latest?.cache, 2)}%</strong>
+              <span>Cache Hit Ratio</span>
+            </div>
+          </div>
+
+          <div className="card">
+            <h3>Quick Explanation</h3>
+            {easySummary.issues.length === 0 && easySummary.warnings.length === 0 && (
+              <p>No immediate problems were detected. Keep monitoring over time.</p>
+            )}
+            {easySummary.issues.length > 0 && (
+              <>
+                <strong>Problems</strong>
+                <ul className="easy-list">
+                  {easySummary.issues.map((item, idx) => <li key={`i-${idx}`}>{item}</li>)}
+                </ul>
+              </>
+            )}
+            {easySummary.warnings.length > 0 && (
+              <>
+                <strong>Things to watch</strong>
+                <ul className="easy-list">
+                  {easySummary.warnings.map((item, idx) => <li key={`w-${idx}`}>{item}</li>)}
+                </ul>
+              </>
+            )}
+          </div>
+
+          <div className="grid two">
+            <div className="card">
+              <h3>Instance Summary</h3>
+              <div className="overview-metrics">
+                <div><span>Role</span><strong>{overview.instance.role}</strong></div>
+                <div><span>Uptime</span><strong>{formatSeconds(overview.instance.uptime_seconds)}</strong></div>
+                <div><span>Target Port</span><strong>{targetMeta?.port ?? "-"}</strong></div>
+                <div><span>Current DB Size</span><strong>{formatBytes(overview.storage.current_database_size_bytes)}</strong></div>
+                <div><span>Replication Clients</span><strong>{overview.replication.active_replication_clients ?? "-"}</strong></div>
+                <div><span>Autovacuum Workers</span><strong>{overview.performance.autovacuum_workers ?? "-"}</strong></div>
+              </div>
+            </div>
+            <div className="card">
+              <h3>Activity Snapshot</h3>
+              <div className="overview-metrics">
+                <div><span>Running Sessions</span><strong>{activity.filter((a) => a.state === "active").length}</strong></div>
+                <div><span>Total Sessions</span><strong>{activity.length}</strong></div>
+                <div><span>Current Locks</span><strong>{locks.length}</strong></div>
+                <div><span>Deadlocks</span><strong>{overview.performance.deadlocks ?? 0}</strong></div>
+              </div>
+            </div>
+          </div>
+        </>
+      )}
+
+      {uiMode === "dba" && overview && (
         <div className="card">
           <h3>Database Overview</h3>
+          <p className="muted" style={{ marginTop: 2 }}>
+            Agentless mode: host-level CPU, RAM, and free-disk metrics are not available.
+          </p>
           <div className="grid three overview-kv">
             <div><span>PostgreSQL Version</span><strong>{overview.instance.server_version || "-"}</strong></div>
             <div>
               <span>Role</span>
               <strong className={isPrimary ? "pill primary" : isStandby ? "pill standby" : "pill"}>{role}</strong>
             </div>
-            <div title="Zeit seit Start des Postgres-Prozesses">
+            <div title="Time since PostgreSQL postmaster start">
               <span>Uptime</span><strong>{formatSeconds(overview.instance.uptime_seconds)}</strong>
             </div>
             <div><span>Database</span><strong>{overview.instance.current_database || "-"}</strong></div>
@@ -165,16 +414,16 @@ export function TargetDetailPage() {
               <span>Target Port</span>
               <strong>{targetMeta?.port ?? "-"}</strong>
             </div>
-            <div title="Groesse der aktuell verbundenen Datenbank">
+            <div title="Current database total size">
               <span>Current DB Size</span><strong>{formatBytes(overview.storage.current_database_size_bytes)}</strong>
             </div>
-            <div title="Gesamtgroesse der WAL-Dateien (falls verfuegbar)">
+            <div title="Total WAL directory size (when available)">
               <span>WAL Size</span><strong>{formatBytes(overview.storage.wal_directory_size_bytes)}</strong>
             </div>
-            <div title="Optional ueber Agent/SSH ermittelbar">
-              <span>Free Disk</span><strong>{formatBytes(overview.storage.disk_space.free_bytes)}</strong>
+            <div title={overview.storage.disk_space?.message || "Agentless mode: host-level free disk is unavailable."}>
+              <span>Free Disk</span><strong>{formatDiskSpaceAgentless(overview.storage.disk_space)}</strong>
             </div>
-            <div title="Zeitliche Replikationsverzoegerung auf Standby">
+            <div title="Replication replay delay on standby">
               <span>Replay Lag</span>
               <strong className={overview.replication.replay_lag_seconds > 5 ? "lag-bad" : ""}>
                 {formatSeconds(overview.replication.replay_lag_seconds)}
@@ -183,6 +432,12 @@ export function TargetDetailPage() {
             <div><span>Replication Slots</span><strong>{overview.replication.replication_slots_count ?? "-"}</strong></div>
             <div><span>Repl Clients</span><strong>{overview.replication.active_replication_clients ?? "-"}</strong></div>
             <div><span>Autovacuum Workers</span><strong>{overview.performance.autovacuum_workers ?? "-"}</strong></div>
+            <div title="Host CPU requires OS-level telemetry">
+              <span>Host CPU</span><strong>{formatHostMetricUnavailable()}</strong>
+            </div>
+            <div title="Host RAM requires OS-level telemetry">
+              <span>Host RAM</span><strong>{formatHostMetricUnavailable()}</strong>
+            </div>
           </div>
 
           <div className="grid two">
@@ -255,23 +510,43 @@ export function TargetDetailPage() {
         </div>
       )}
       <div className="range-picker">
+        <button
+          type="button"
+          className={`live-btn ${liveMode ? "active" : ""}`}
+          onClick={() => {
+            setLiveMode((prev) => {
+              const next = !prev;
+              if (next) setRange("15m");
+              return next;
+            });
+          }}
+        >
+          LIVE
+        </button>
         {Object.keys(ranges).map((r) => (
-          <button key={r} onClick={() => setRange(r)} className={r === range ? "active" : ""}>
+          <button
+            key={r}
+            onClick={() => {
+              setLiveMode(false);
+              setRange(r);
+            }}
+            className={r === range ? "active" : ""}
+          >
             {r}
           </button>
         ))}
       </div>
       <div className="card" style={{ height: 320 }}>
-        <h3>Connections / TPS approx / Cache hit ratio</h3>
+        <h3>Connections / TPS (approx) / Cache Hit Ratio</h3>
         <ResponsiveContainer width="100%" height="85%">
           <LineChart data={chartData}>
             <XAxis dataKey="ts" hide />
             <YAxis yAxisId="left" />
             <YAxis yAxisId="right" orientation="right" domain={[0, 100]} />
             <Tooltip content={<MetricsTooltip />} />
-            <Line yAxisId="left" type="monotone" dataKey="connections" stroke="#38bdf8" dot={false} strokeWidth={2} />
-            <Line yAxisId="left" type="monotone" dataKey="tps" stroke="#22c55e" dot={false} strokeWidth={2} />
-            <Line yAxisId="right" type="monotone" dataKey="cache" stroke="#f59e0b" dot={false} strokeWidth={2} />
+            <Line yAxisId="left" type="monotone" dataKey="connections" stroke="#38bdf8" dot={false} strokeWidth={2} isAnimationActive={false} />
+            <Line yAxisId="left" type="monotone" dataKey="tps" stroke="#22c55e" dot={false} strokeWidth={2} isAnimationActive={false} />
+            <Line yAxisId="right" type="monotone" dataKey="cache" stroke="#f59e0b" dot={false} strokeWidth={2} isAnimationActive={false} />
           </LineChart>
         </ResponsiveContainer>
       </div>

frontend/src/pages/TargetsPage.jsx

@@ -1,9 +1,24 @@
-import React, { useEffect, useState } from "react";
+import React, { useEffect, useRef, useState } from "react";
 import { Link } from "react-router-dom";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
 
 const emptyForm = {
+  name: "",
+  host: "",
+  port: 5432,
+  dbname: "postgres",
+  username: "",
+  password: "",
+  sslmode: "prefer",
+  use_pg_stat_statements: true,
+  discover_all_databases: false,
+  owner_user_ids: [],
+  tags: {},
+};
+
+const emptyEditForm = {
+  id: null,
   name: "",
   host: "",
   port: 5432,
@@ -11,22 +26,120 @@ const emptyForm = {
   username: "",
   password: "",
   sslmode: "prefer",
-  tags: {},
+  use_pg_stat_statements: true,
+  owner_user_ids: [],
 };
 
+function toggleOwner(ids, userId) {
+  return ids.includes(userId) ? ids.filter((id) => id !== userId) : [...ids, userId];
+}
+
+function OwnerPicker({ candidates, selectedIds, onToggle, query, onQueryChange }) {
+  const pickerRef = useRef(null);
+  const [open, setOpen] = useState(false);
+  const filtered = candidates.filter((item) =>
+    item.email.toLowerCase().includes(query.trim().toLowerCase())
+  );
+  const selected = candidates.filter((item) => selectedIds.includes(item.user_id));
+
+  useEffect(() => {
+    const onPointerDown = (event) => {
+      if (!pickerRef.current?.contains(event.target)) {
+        setOpen(false);
+      }
+    };
+    document.addEventListener("mousedown", onPointerDown);
+    return () => document.removeEventListener("mousedown", onPointerDown);
+  }, []);
+
+  return (
+    <div className="owner-picker" ref={pickerRef}>
+      <div className="owner-selected">
+        {selected.length > 0 ? (
+          selected.map((item) => (
+            <button
+              key={`selected-${item.user_id}`}
+              type="button"
+              className="owner-selected-chip"
+              onClick={() => onToggle(item.user_id)}
+              title="Remove owner"
+            >
+              <span>{item.email}</span>
+              <span aria-hidden="true">x</span>
+            </button>
+          ))
+        ) : (
+          <span className="muted">No owners selected yet.</span>
+        )}
+      </div>
+      <div className={`owner-search-shell ${open ? "open" : ""}`}>
+        <input
+          type="text"
+          className="owner-search-input"
+          value={query}
+          onChange={(e) => onQueryChange(e.target.value)}
+          onFocus={() => setOpen(true)}
+          onClick={() => setOpen(true)}
+          placeholder="Search users by email..."
+        />
+        <button type="button" className="owner-search-toggle" onClick={() => setOpen((prev) => !prev)}>
+          v
+        </button>
+      </div>
+      {open && (
+        <div className="owner-dropdown">
+          <div className="owner-search-results">
+            {filtered.map((item) => {
+              const active = selectedIds.includes(item.user_id);
+              return (
+                <button
+                  key={item.user_id}
+                  type="button"
+                  className={`owner-result ${active ? "active" : ""}`}
+                  onClick={() => onToggle(item.user_id)}
+                >
+                  <span>{item.email}</span>
+                  <small>{item.role}</small>
+                </button>
+              );
+            })}
+            {filtered.length === 0 && <div className="owner-result-empty">No matching users.</div>}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}
+
 export function TargetsPage() {
   const { tokens, refresh, me } = useAuth();
   const [targets, setTargets] = useState([]);
   const [form, setForm] = useState(emptyForm);
+  const [editForm, setEditForm] = useState(emptyEditForm);
+  const [editing, setEditing] = useState(false);
   const [error, setError] = useState("");
   const [loading, setLoading] = useState(true);
+  const [testState, setTestState] = useState({ loading: false, message: "", ok: null });
+  const [saveState, setSaveState] = useState({ loading: false, message: "" });
+  const [ownerCandidates, setOwnerCandidates] = useState([]);
+  const [createOwnerQuery, setCreateOwnerQuery] = useState("");
+  const [editOwnerQuery, setEditOwnerQuery] = useState("");
 
   const canManage = me?.role === "admin" || me?.role === "operator";
 
   const load = async () => {
     setLoading(true);
     try {
+      if (canManage) {
+        const [targetRows, candidates] = await Promise.all([
+          apiFetch("/targets", {}, tokens, refresh),
+          apiFetch("/targets/owner-candidates", {}, tokens, refresh),
+        ]);
+        setTargets(targetRows);
+        setOwnerCandidates(candidates);
+      } else {
         setTargets(await apiFetch("/targets", {}, tokens, refresh));
+      }
       setError("");
     } catch (e) {
       setError(String(e.message || e));
@@ -37,7 +150,7 @@ export function TargetsPage() {
 
   useEffect(() => {
     load();
-  }, []);
+  }, [canManage]);
 
   const createTarget = async (e) => {
     e.preventDefault();
@@ -50,8 +163,33 @@ export function TargetsPage() {
     }
   };
 
+  const testConnection = async () => {
+    setTestState({ loading: true, message: "", ok: null });
+    try {
+      const result = await apiFetch(
+        "/targets/test-connection",
+        {
+          method: "POST",
+          body: JSON.stringify({
+            host: form.host,
+            port: form.port,
+            dbname: form.dbname,
+            username: form.username,
+            password: form.password,
+            sslmode: form.sslmode,
+          }),
+        },
+        tokens,
+        refresh
+      );
+      setTestState({ loading: false, message: `${result.message} (PostgreSQL ${result.server_version})`, ok: true });
+    } catch (e) {
+      setTestState({ loading: false, message: String(e.message || e), ok: false });
+    }
+  };
+
   const deleteTarget = async (id) => {
-    if (!confirm("Target löschen?")) return;
+    if (!confirm("Delete target?")) return;
     try {
       await apiFetch(`/targets/${id}`, { method: "DELETE" }, tokens, refresh);
       await load();
@@ -60,41 +198,105 @@ export function TargetsPage() {
     }
   };
 
+  const startEdit = (target) => {
+    setEditing(true);
+    setSaveState({ loading: false, message: "" });
+    setEditOwnerQuery("");
+    setEditForm({
+      id: target.id,
+      name: target.name,
+      host: target.host,
+      port: target.port,
+      dbname: target.dbname,
+      username: target.username,
+      password: "",
+      sslmode: target.sslmode,
+      use_pg_stat_statements: target.use_pg_stat_statements !== false,
+      owner_user_ids: Array.isArray(target.owner_user_ids) ? target.owner_user_ids : [],
+    });
+  };
+
+  const cancelEdit = () => {
+    setEditing(false);
+    setEditForm(emptyEditForm);
+    setSaveState({ loading: false, message: "" });
+  };
+
+  const saveEdit = async (e) => {
+    e.preventDefault();
+    if (!editForm.id) return;
+    setSaveState({ loading: true, message: "" });
+    try {
+      const payload = {
+        name: editForm.name,
+        host: editForm.host,
+        port: Number(editForm.port),
+        dbname: editForm.dbname,
+        username: editForm.username,
+        sslmode: editForm.sslmode,
+        use_pg_stat_statements: !!editForm.use_pg_stat_statements,
+        owner_user_ids: editForm.owner_user_ids || [],
+      };
+      if (editForm.password.trim()) payload.password = editForm.password;
+
+      await apiFetch(`/targets/${editForm.id}`, { method: "PUT", body: JSON.stringify(payload) }, tokens, refresh);
+      setSaveState({ loading: false, message: "Target updated." });
+      setEditing(false);
+      setEditForm(emptyEditForm);
+      await load();
+    } catch (e) {
+      setSaveState({ loading: false, message: String(e.message || e) });
+    }
+  };
+
   return (
-    <div>
+    <div className="targets-page">
       <h2>Targets Management</h2>
       {error && <div className="card error">{error}</div>}
+
       {canManage && (
-        <form className="card grid two" onSubmit={createTarget}>
+        <details className="card collapsible">
+          <summary className="collapse-head">
+            <div>
+              <h3>New Target</h3>
+            </div>
+            <span className="collapse-chevron" aria-hidden="true">v</span>
+          </summary>
+
+          <form className="target-form grid two" onSubmit={createTarget}>
             <div className="field">
               <label>Name</label>
-            <input placeholder="z.B. Prod-DB" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
-            <small>Eindeutiger Anzeigename im Dashboard.</small>
+              <input placeholder="e.g. Prod-DB" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
             </div>
             <div className="field">
               <label>Host</label>
-            <input placeholder="z.B. 172.16.0.106 oder db.internal" value={form.host} onChange={(e) => setForm({ ...form, host: e.target.value })} required />
-            <small>Wichtig: Muss vom Backend-Container aus erreichbar sein.</small>
+              <input placeholder="e.g. 172.16.0.106 or db.internal" value={form.host} onChange={(e) => setForm({ ...form, host: e.target.value })} required />
             </div>
             <div className="field">
               <label>Port</label>
               <input placeholder="5432" value={form.port} onChange={(e) => setForm({ ...form, port: Number(e.target.value) })} type="number" required />
-            <small>Standard PostgreSQL Port ist 5432 (oder gemappter Host-Port).</small>
             </div>
             <div className="field">
-            <label>DB Name</label>
-            <input placeholder="z.B. postgres oder appdb" value={form.dbname} onChange={(e) => setForm({ ...form, dbname: e.target.value })} required />
-            <small>Name der Datenbank, die überwacht werden soll.</small>
+              <label>{form.discover_all_databases ? "Discovery DB" : "DB Name"}</label>
+              <input
+                placeholder={form.discover_all_databases ? "e.g. postgres" : "e.g. postgres or appdb"}
+                value={form.dbname}
+                onChange={(e) => setForm({ ...form, dbname: e.target.value })}
+                required
+              />
+              <small>
+                {form.discover_all_databases
+                  ? "Connection database used to crawl all available databases on this instance."
+                  : "Single database to monitor for this target."}
+              </small>
             </div>
             <div className="field">
               <label>Username</label>
-            <input placeholder="z.B. postgres" value={form.username} onChange={(e) => setForm({ ...form, username: e.target.value })} required />
-            <small>DB User mit Leserechten auf Stats-Views.</small>
+              <input placeholder="e.g. postgres" value={form.username} onChange={(e) => setForm({ ...form, username: e.target.value })} required />
             </div>
             <div className="field">
               <label>Password</label>
-            <input placeholder="Passwort" type="password" value={form.password} onChange={(e) => setForm({ ...form, password: e.target.value })} required />
-            <small>Wird verschlüsselt in der Core-DB gespeichert.</small>
+              <input placeholder="Password" type="password" value={form.password} onChange={(e) => setForm({ ...form, password: e.target.value })} required />
             </div>
             <div className="field">
               <label>SSL Mode</label>
@@ -104,32 +306,162 @@ export function TargetsPage() {
                 <option value="require">require</option>
               </select>
               <small>
-              Bei Fehler "rejected SSL upgrade" auf <code>disable</code> stellen.
+                If you see "rejected SSL upgrade", switch to <code>disable</code>.
               </small>
             </div>
-          <div className="field">
-            <label>&nbsp;</label>
-            <button>Target anlegen</button>
+            <div className="field toggle-field">
+              <label>Query Insights Source</label>
+              <label className="toggle-check">
+                <input
+                  type="checkbox"
+                  checked={!!form.use_pg_stat_statements}
+                  onChange={(e) => setForm({ ...form, use_pg_stat_statements: e.target.checked })}
+                />
+                <span className="toggle-ui" aria-hidden="true" />
+                <span className="toggle-copy">
+                  <strong>Use pg_stat_statements for this target</strong>
+                  <small>Disable this if the extension is unavailable on the target.</small>
+                </span>
+              </label>
+            </div>
+            <div className="field toggle-field">
+              <label>Scope</label>
+              <label className="toggle-check">
+                <input
+                  type="checkbox"
+                  checked={!!form.discover_all_databases}
+                  onChange={(e) => setForm({ ...form, discover_all_databases: e.target.checked })}
+                />
+                <span className="toggle-ui" aria-hidden="true" />
+                <span className="toggle-copy">
+                  <strong>Discover and add all databases</strong>
+                  <small>Requires credentials with access to list databases (typically a superuser).</small>
+                </span>
+              </label>
+            </div>
+            <div className="field field-full">
+              <label>Responsible Users (Target Owners)</label>
+              <OwnerPicker
+                candidates={ownerCandidates}
+                selectedIds={form.owner_user_ids}
+                query={createOwnerQuery}
+                onQueryChange={setCreateOwnerQuery}
+                onToggle={(userId) => setForm({ ...form, owner_user_ids: toggleOwner(form.owner_user_ids, userId) })}
+              />
+              <small>Only selected users will receive email notifications for this target's alerts.</small>
+            </div>
+            <div className="field submit-field field-full">
+              <div className="form-actions">
+                <button type="button" className="secondary-btn" onClick={testConnection} disabled={testState.loading}>
+                  {testState.loading ? "Testing..." : "Test connection"}
+                </button>
+                <button className="primary-btn">Create target</button>
+              </div>
             </div>
           </form>
+          {testState.message && (
+            <div className={`test-connection-result ${testState.ok ? "ok" : "fail"}`}>{testState.message}</div>
           )}
-      {canManage && (
-        <div className="card tips">
-          <strong>Troubleshooting</strong>
-          <p>
-            <code>Connection refused</code>: Host/Port falsch oder DB nicht erreichbar.
-          </p>
-          <p>
-            <code>rejected SSL upgrade</code>: SSL Mode auf <code>disable</code> setzen.
-          </p>
-          <p>
-            <code>localhost</code> im Target zeigt aus Backend-Container-Sicht auf den Container selbst.
-          </p>
+        </details>
+      )}
+
+      {canManage && editing && (
+        <section className="card">
+          <h3>Edit Target</h3>
+          <form className="target-form grid two" onSubmit={saveEdit}>
+            <div className="field">
+              <label>Name</label>
+              <input value={editForm.name} onChange={(e) => setEditForm({ ...editForm, name: e.target.value })} required />
             </div>
+            <div className="field">
+              <label>Host</label>
+              <input value={editForm.host} onChange={(e) => setEditForm({ ...editForm, host: e.target.value })} required />
+            </div>
+            <div className="field">
+              <label>Port</label>
+              <input type="number" value={editForm.port} onChange={(e) => setEditForm({ ...editForm, port: Number(e.target.value) })} required />
+            </div>
+            <div className="field">
+              <label>DB Name</label>
+              <input value={editForm.dbname} onChange={(e) => setEditForm({ ...editForm, dbname: e.target.value })} required />
+            </div>
+            <div className="field">
+              <label>Username</label>
+              <input value={editForm.username} onChange={(e) => setEditForm({ ...editForm, username: e.target.value })} required />
+            </div>
+            <div className="field">
+              <label>New Password (optional)</label>
+              <input type="password" placeholder="Leave empty to keep current" value={editForm.password} onChange={(e) => setEditForm({ ...editForm, password: e.target.value })} />
+            </div>
+            <div className="field">
+              <label>SSL Mode</label>
+              <select value={editForm.sslmode} onChange={(e) => setEditForm({ ...editForm, sslmode: e.target.value })}>
+                <option value="disable">disable</option>
+                <option value="prefer">prefer</option>
+                <option value="require">require</option>
+              </select>
+            </div>
+            <div className="field toggle-field">
+              <label>Query Insights Source</label>
+              <label className="toggle-check">
+                <input
+                  type="checkbox"
+                  checked={!!editForm.use_pg_stat_statements}
+                  onChange={(e) => setEditForm({ ...editForm, use_pg_stat_statements: e.target.checked })}
+                />
+                <span className="toggle-ui" aria-hidden="true" />
+                <span className="toggle-copy">
+                  <strong>Use pg_stat_statements for this target</strong>
+                  <small>Disable this if the extension is unavailable on the target.</small>
+                </span>
+              </label>
+            </div>
+            <div className="field field-full">
+              <label>Responsible Users (Target Owners)</label>
+              <OwnerPicker
+                candidates={ownerCandidates}
+                selectedIds={editForm.owner_user_ids}
+                query={editOwnerQuery}
+                onQueryChange={setEditOwnerQuery}
+                onToggle={(userId) => setEditForm({ ...editForm, owner_user_ids: toggleOwner(editForm.owner_user_ids, userId) })}
+              />
+              <small>Only selected users will receive email notifications for this target's alerts.</small>
+            </div>
+            <div className="field submit-field field-full">
+              <div className="form-actions">
+                <button type="button" className="secondary-btn" onClick={cancelEdit}>Cancel</button>
+                <button className="primary-btn" disabled={saveState.loading}>{saveState.loading ? "Saving..." : "Save changes"}</button>
+              </div>
+            </div>
+          </form>
+          {saveState.message && <div className="test-connection-result">{saveState.message}</div>}
+        </section>
       )}
-      <div className="card">
+
+      {canManage && (
+        <details className="card collapsible tips">
+          <summary className="collapse-head">
+            <div>
+              <h3>Troubleshooting</h3>
+              <p>Quick checks for the most common connection issues.</p>
+            </div>
+            <span className="collapse-chevron" aria-hidden="true">v</span>
+          </summary>
+          <p>
+            <code>Connection refused</code>: host/port is wrong or database is unreachable.
+          </p>
+          <p>
+            <code>rejected SSL upgrade</code>: set SSL mode to <code>disable</code>.
+          </p>
+          <p>
+            <code>localhost</code> points to the backend container itself, not your host machine.
+          </p>
+        </details>
+      )}
+
+      <div className="card targets-table">
         {loading ? (
-          <p>Lade Targets...</p>
+          <p>Loading targets...</p>
         ) : (
           <table>
             <thead>
@@ -137,7 +469,9 @@ export function TargetsPage() {
                 <th>Name</th>
                 <th>Host</th>
                 <th>DB</th>
-                <th>Aktionen</th>
+                <th>Owners</th>
+                <th>Query Insights</th>
+                <th>Actions</th>
               </tr>
             </thead>
             <tbody>
@@ -146,9 +480,43 @@ export function TargetsPage() {
                   <td>{t.name}</td>
                   <td>{t.host}:{t.port}</td>
                   <td>{t.dbname}</td>
+                  <td>{Array.isArray(t.owner_user_ids) ? t.owner_user_ids.length : 0}</td>
                   <td>
-                    <Link to={`/targets/${t.id}`}>Details</Link>{" "}
-                    {canManage && <button onClick={() => deleteTarget(t.id)}>Delete</button>}
+                    <span className={`status-chip ${t.use_pg_stat_statements ? "ok" : "warning"}`}>
+                      {t.use_pg_stat_statements ? "Enabled" : "Disabled"}
+                    </span>
+                  </td>
+                  <td>
+                    <div className="row-actions">
+                      <Link className="table-action-btn details" to={`/targets/${t.id}`}>
+                        <span aria-hidden="true">
+                          <svg viewBox="0 0 24 24" width="13" height="13">
+                            <path d="M2 12s3.5-6 10-6 10 6 10 6-3.5 6-10 6-10-6-10-6zm10 3a3 3 0 1 0 0-6 3 3 0 0 0 0 6z" fill="currentColor" />
+                          </svg>
+                        </span>
+                        Details
+                      </Link>
+                      {canManage && (
+                        <button className="table-action-btn edit" onClick={() => startEdit(t)}>
+                          <span aria-hidden="true">
+                            <svg viewBox="0 0 24 24" width="13" height="13">
+                              <path d="M3 17.25V21h3.75L19.81 7.94l-3.75-3.75L3 17.25zm2.92 2.33H5v-.92l10.06-10.06.92.92L5.92 19.58zM20.71 6.04a1 1 0 0 0 0-1.41L19.37 3.3a1 1 0 0 0-1.41 0l-1.13 1.12 3.75 3.75 1.13-1.13z" fill="currentColor" />
+                            </svg>
+                          </span>
+                          Edit
+                        </button>
+                      )}
+                      {canManage && (
+                        <button className="table-action-btn delete" onClick={() => deleteTarget(t.id)}>
+                          <span aria-hidden="true">
+                            <svg viewBox="0 0 24 24" width="13" height="13">
+                              <path d="M6 7h12l-1 13H7L6 7zm3-3h6l1 2H8l1-2z" fill="currentColor" />
+                            </svg>
+                          </span>
+                          Delete
+                        </button>
+                      )}
+                    </div>
                   </td>
                 </tr>
               ))}

frontend/src/pages/UserSettingsPage.jsx

@@ -0,0 +1,100 @@
+import React, { useState } from "react";
+import { apiFetch } from "../api";
+import { useAuth } from "../state";
+
+export function UserSettingsPage() {
+  const { tokens, refresh } = useAuth();
+  const [form, setForm] = useState({
+    current_password: "",
+    new_password: "",
+    confirm_password: "",
+  });
+  const [message, setMessage] = useState("");
+  const [error, setError] = useState("");
+  const [busy, setBusy] = useState(false);
+
+  const submit = async (e) => {
+    e.preventDefault();
+    setMessage("");
+    setError("");
+    if (form.new_password.length < 8) {
+      setError("New password must be at least 8 characters.");
+      return;
+    }
+    if (form.new_password !== form.confirm_password) {
+      setError("Password confirmation does not match.");
+      return;
+    }
+
+    try {
+      setBusy(true);
+      await apiFetch(
+        "/me/password",
+        {
+          method: "POST",
+          body: JSON.stringify({
+            current_password: form.current_password,
+            new_password: form.new_password,
+          }),
+        },
+        tokens,
+        refresh
+      );
+      setForm({ current_password: "", new_password: "", confirm_password: "" });
+      setMessage("Password changed successfully.");
+    } catch (e) {
+      setError(String(e.message || e));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <div className="user-settings-page">
+      <h2>User Settings</h2>
+      <p className="muted">Manage your personal account security settings.</p>
+      {error && <div className="card error">{error}</div>}
+      {message && <div className="test-connection-result ok">{message}</div>}
+
+      <div className="card user-settings-card">
+        <h3>Change Password</h3>
+        <form className="grid two" onSubmit={submit}>
+          <div className="admin-field field-full">
+            <label>Current password</label>
+            <input
+              type="password"
+              value={form.current_password}
+              onChange={(e) => setForm({ ...form, current_password: e.target.value })}
+              required
+            />
+          </div>
+          <div className="admin-field">
+            <label>New password</label>
+            <input
+              type="password"
+              value={form.new_password}
+              onChange={(e) => setForm({ ...form, new_password: e.target.value })}
+              minLength={8}
+              required
+            />
+          </div>
+          <div className="admin-field">
+            <label>Confirm new password</label>
+            <input
+              type="password"
+              value={form.confirm_password}
+              onChange={(e) => setForm({ ...form, confirm_password: e.target.value })}
+              minLength={8}
+              required
+            />
+          </div>
+          <div className="form-actions field-full">
+            <button className="primary-btn" type="submit" disabled={busy}>
+              {busy ? "Saving..." : "Update Password"}
+            </button>
+          </div>
+        </form>
+      </div>
+    </div>
+  );
+}

frontend/src/state.jsx

@@ -1,7 +1,8 @@
-import React, { createContext, useContext, useMemo, useState } from "react";
+import React, { createContext, useContext, useEffect, useMemo, useRef, useState } from "react";
 import { API_URL } from "./api";
 
 const AuthCtx = createContext(null);
+const UI_MODE_KEY = "nexapg_ui_mode";
 
 function loadStorage() {
   try {
@@ -11,10 +12,26 @@ function loadStorage() {
   }
 }
 
+function loadUiMode() {
+  try {
+    const value = localStorage.getItem(UI_MODE_KEY);
+    if (value === "easy" || value === "dba") return value;
+  } catch {
+    // ignore storage errors
+  }
+  return "dba";
+}
+
 export function AuthProvider({ children }) {
   const initial = loadStorage();
   const [tokens, setTokens] = useState(initial?.tokens || null);
   const [me, setMe] = useState(initial?.me || null);
+  const [uiMode, setUiModeState] = useState(loadUiMode);
+  const [alertStatus, setAlertStatus] = useState({ warnings: [], alerts: [], warning_count: 0, alert_count: 0 });
+  const [alertToasts, setAlertToasts] = useState([]);
+  const [serviceInfo, setServiceInfo] = useState(null);
+  const knownAlertKeysRef = useRef(new Set());
+  const hasAlertSnapshotRef = useRef(false);
 
   const persist = (nextTokens, nextMe) => {
     if (nextTokens && nextMe) {
@@ -78,7 +95,153 @@ export function AuthProvider({ children }) {
     }
   };
 
-  const value = useMemo(() => ({ tokens, me, login, logout, refresh }), [tokens, me]);
+  const dismissAlertToast = (toastId) => {
+    setAlertToasts((prev) => prev.map((t) => (t.id === toastId ? { ...t, closing: true } : t)));
+    setTimeout(() => {
+      setAlertToasts((prev) => prev.filter((t) => t.id !== toastId));
+    }, 220);
+  };
+
+  useEffect(() => {
+    if (!tokens?.accessToken) {
+      setAlertStatus({ warnings: [], alerts: [], warning_count: 0, alert_count: 0 });
+      setAlertToasts([]);
+      knownAlertKeysRef.current = new Set();
+      hasAlertSnapshotRef.current = false;
+      return;
+    }
+
+    let mounted = true;
+
+    const pushToastsForNewItems = (items) => {
+      if (!items.length) return;
+      const createdAt = Date.now();
+      const nextToasts = items.slice(0, 4).map((item, idx) => ({
+        id: `${createdAt}-${idx}-${item.alert_key}`,
+        alertKey: item.alert_key,
+        severity: item.severity,
+        title: item.name,
+        target: item.target_name,
+        message: item.message,
+        closing: false,
+      }));
+      setAlertToasts((prev) => [...nextToasts, ...prev].slice(0, 6));
+      for (const toast of nextToasts) {
+        setTimeout(() => {
+          if (!mounted) return;
+          dismissAlertToast(toast.id);
+        }, 8000);
+      }
+    };
+
+    const loadAlertStatus = async () => {
+      const request = async (accessToken) =>
+        fetch(`${API_URL}/alerts/status`, {
+          headers: { Authorization: `Bearer ${accessToken}` },
+        });
+
+      let res = await request(tokens.accessToken);
+      if (res.status === 401 && tokens.refreshToken) {
+        const refreshed = await refresh();
+        if (refreshed?.accessToken) {
+          res = await request(refreshed.accessToken);
+        }
+      }
+      if (!res.ok) return;
+
+      const payload = await res.json();
+      if (!mounted) return;
+      setAlertStatus(payload);
+
+      const currentItems = [...(payload.warnings || []), ...(payload.alerts || [])];
+      const currentKeys = new Set(currentItems.map((item) => item.alert_key));
+      if (!hasAlertSnapshotRef.current) {
+        knownAlertKeysRef.current = currentKeys;
+        hasAlertSnapshotRef.current = true;
+        return;
+      }
+      const newItems = currentItems.filter((item) => !knownAlertKeysRef.current.has(item.alert_key));
+      knownAlertKeysRef.current = currentKeys;
+      pushToastsForNewItems(newItems);
+    };
+
+    loadAlertStatus().catch(() => {});
+    const timer = setInterval(() => {
+      loadAlertStatus().catch(() => {});
+    }, 8000);
+
+    return () => {
+      mounted = false;
+      clearInterval(timer);
+    };
+  }, [tokens?.accessToken, tokens?.refreshToken]);
+
+  useEffect(() => {
+    if (!tokens?.accessToken) {
+      setServiceInfo(null);
+      return;
+    }
+
+    let mounted = true;
+
+    const request = async (path, method = "GET") => {
+      const doFetch = async (accessToken) =>
+        fetch(`${API_URL}${path}`, {
+          method,
+          headers: { Authorization: `Bearer ${accessToken}` },
+        });
+
+      let res = await doFetch(tokens.accessToken);
+      if (res.status === 401 && tokens.refreshToken) {
+        const refreshed = await refresh();
+        if (refreshed?.accessToken) {
+          res = await doFetch(refreshed.accessToken);
+        }
+      }
+      if (!res.ok) return null;
+      return res.json();
+    };
+
+    const runServiceCheck = async () => {
+      await request("/service/info/check", "POST");
+      const info = await request("/service/info", "GET");
+      if (mounted && info) setServiceInfo(info);
+    };
+
+    runServiceCheck().catch(() => {});
+    const timer = setInterval(() => {
+      runServiceCheck().catch(() => {});
+    }, 30000);
+
+    return () => {
+      mounted = false;
+      clearInterval(timer);
+    };
+  }, [tokens?.accessToken, tokens?.refreshToken]);
+
+  const setUiMode = (nextMode) => {
+    const mode = nextMode === "easy" ? "easy" : "dba";
+    setUiModeState(mode);
+    localStorage.setItem(UI_MODE_KEY, mode);
+  };
+
+  const value = useMemo(
+    () => ({
+      tokens,
+      me,
+      login,
+      logout,
+      refresh,
+      uiMode,
+      setUiMode,
+      alertStatus,
+      alertToasts,
+      dismissAlertToast,
+      serviceInfo,
+      serviceUpdateAvailable: !!serviceInfo?.update_available,
+    }),
+    [tokens, me, uiMode, alertStatus, alertToasts, serviceInfo]
+  );
   return <AuthCtx.Provider value={value}>{children}</AuthCtx.Provider>;
 }
 

ops/.env.example

@@ -1,27 +1,57 @@
-# App
+# ------------------------------
+# Application
+# ------------------------------
+# Display name used in API docs/UI.
 APP_NAME=NexaPG Monitor
+# Runtime environment: dev | staging | prod | test
 ENVIRONMENT=dev
+# Backend log level: DEBUG | INFO | WARNING | ERROR
 LOG_LEVEL=INFO
 
-# Core DB
+# ------------------------------
+# Core Database (internal metadata DB)
+# ------------------------------
+# Database that stores users, targets, metrics, query stats, and audit logs.
 DB_NAME=nexapg
 DB_USER=nexapg
 DB_PASSWORD=nexapg
+# Host port mapped to the internal PostgreSQL container port 5432.
 DB_PORT=5433
 
-# Backend
+# ------------------------------
+# Backend API
+# ------------------------------
+# Host port mapped to backend container port 8000.
 BACKEND_PORT=8000
+# JWT signing secret. Change this in every non-local environment.
 JWT_SECRET_KEY=change_this_super_secret
 JWT_ALGORITHM=HS256
+# Access token lifetime in minutes.
 JWT_ACCESS_TOKEN_MINUTES=15
+# Refresh token lifetime in minutes (10080 = 7 days).
 JWT_REFRESH_TOKEN_MINUTES=10080
-# Generate with: python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
+# Key used to encrypt monitored target passwords at rest.
+# Generate with:
+# python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
 ENCRYPTION_KEY=REPLACE_WITH_FERNET_KEY
+# Allowed CORS origins for browser clients.
+# Use comma-separated values, e.g.:
+# CORS_ORIGINS=http://localhost:5173,https://nexapg.example.com
+# Dev-only shortcut:
+# CORS_ORIGINS=*
 CORS_ORIGINS=http://localhost:5173,http://localhost:8080
+# Target polling interval in seconds.
 POLL_INTERVAL_SECONDS=30
+# Initial admin bootstrap user (created on first startup if not present).
 INIT_ADMIN_EMAIL=admin@example.com
 INIT_ADMIN_PASSWORD=ChangeMe123!
 
+# ------------------------------
 # Frontend
+# ------------------------------
+# Host port mapped to frontend container port 80.
 FRONTEND_PORT=5173
-VITE_API_URL=http://localhost:8000/api/v1
+# Base API URL used at frontend build time.
+# For reverse proxy + SSL, keep this relative to avoid mixed-content issues.
+# Example direct mode: VITE_API_URL=http://localhost:8000/api/v1
+VITE_API_URL=/api/v1

ops/scripts/bootstrap-compose.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Usage:
+#   bash bootstrap-compose.sh
+#   BASE_URL="https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main" bash bootstrap-compose.sh
+
+BASE_URL="${BASE_URL:-https://git.nesterovic.cc/nessi/NexaPG/raw/branch/main}"
+
+echo "[bootstrap] Using base URL: ${BASE_URL}"
+
+fetch_file() {
+  local path="$1"
+  local out="$2"
+
+  if command -v wget >/dev/null 2>&1; then
+    wget -q -O "${out}" "${BASE_URL}/${path}"
+  elif command -v curl >/dev/null 2>&1; then
+    curl -fsSL "${BASE_URL}/${path}" -o "${out}"
+  else
+    echo "[bootstrap] ERROR: wget or curl is required"
+    exit 1
+  fi
+}
+
+fetch_file "docker-compose.yml" "docker-compose.yml"
+fetch_file ".env.example" ".env.example"
+fetch_file "Makefile" "Makefile"
+
+if [[ ! -f ".env" ]]; then
+  cp .env.example .env
+  echo "[bootstrap] Created .env from .env.example"
+else
+  echo "[bootstrap] .env already exists, keeping it"
+fi
+
+echo
+echo "[bootstrap] Next steps:"
+echo "  1) Edit .env (set JWT_SECRET_KEY and ENCRYPTION_KEY at minimum)"
+echo "  2) Run: make up"
+echo