version 5.2.0

- Add ping_monitor to built-in plugins list
- Update cpu_monitor (uptime) and memory_monitor (ZFS ARC) descriptions
- Replace "aggregated status" bullet with accurate per-check reporting note
- Fix RTT hysteresis default: 0.1 → 0.02
- Fix client YAML config: remove non-existent server:/port: keys, use hb_port:
- Fix nagios_runner commands format: plain strings → {name:, command:} dicts
- Fix Supported Metrics: exit_code → actual <name>_status_code/<name>_status/<name>_output fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -27,6 +27,7 @@ A lightweight daemon that listens for UDP heartbeat messages and acts on them: k
   - Configurable retention and backup management
 - **Plugin system for extensible monitoring** ✅
   - Collect system metrics (CPU, memory, disk, network)
+  - Monitor ZFS pool health, capacity, and I/O via `zpool(8)`
   - Execute existing Nagios monitoring plugins
   - Create custom plugins with simple Python classes
 - **Threshold alerting system** ✅
@@ -34,6 +35,8 @@ A lightweight daemon that listens for UDP heartbeat messages and acts on them: k
   - Hysteresis to prevent alert flapping
   - Automatic notifications on state changes
   - Re-notification for ongoing alerts
+- **Per-host watch flag** — set `watch: false` on any host to silence all notifications for that host without removing its configuration ✅
+- **Role-filtered dashboards** — Live Dashboard and Host Overview show only hosts where the logged-in user is owner or manager (admins see all) ✅
 - Modular codebase suitable for unit testing and CI ✅
 
 ---
@@ -55,21 +58,26 @@ Heartbeat includes a comprehensive plugin architecture that extends monitoring b
 ### Built-in Plugins
 
 - `os_info`: Collects OS, kernel, distribution, and architecture information
-- `cpu_monitor`: Monitors CPU usage, load average, frequency, and process counts
+- `cpu_monitor`: Monitors CPU usage, load average, frequency, process counts, and uptime
-- `memory_monitor`: Monitors RAM and swap usage, available memory
+- `memory_monitor`: Monitors RAM and swap usage, available memory (ZFS ARC-aware)
 - `disk_monitor`: Monitors disk usage, I/O statistics, and filesystem metrics
 - `network_monitor`: Monitors network interface statistics, bandwidth, and connections
+- `ping_monitor`: Measures round-trip latency to configured hosts
 - `filesystem_info`: Collects mounted filesystem information (physical filesystems only by default)
 - `nagios_runner`: Executes Nagios monitoring plugins (check_disk, check_load, check_http, etc.)
+- `zfs_monitor`: Monitors ZFS pool health, capacity, fragmentation, dedup ratio, and cumulative I/O via `zpool(8)`
 
 ### Nagios Integration
 
 The `nagios_runner` plugin provides seamless integration with the vast Nagios plugin ecosystem. You can run any Nagios-compatible plugin and have the results automatically parsed and stored:
 
-- Executes plugins via subprocess with timeout protection
+- Executes plugins asynchronously (non-blocking) with timeout protection
+- Captures both stdout and stderr; if stdout is empty, stderr is used as the status message
+- Handles signal-killed processes (negative exit code → UNKNOWN status)
+- Validates absolute command paths at startup and warns on missing or non-executable files
 - Parses exit codes (OK/WARNING/CRITICAL/UNKNOWN)
 - Extracts performance data with thresholds
-- Reports aggregated status across all configured checks
+- Reports per-check status, exit code, and output; no aggregate rollup field
 
 See [docs/NAGIOS_INTEGRATION.md](docs/NAGIOS_INTEGRATION.md) for complete integration guide including configuration examples and custom plugin development.
 
@@ -147,9 +155,11 @@ Heartbeat includes a sophisticated threshold alerting system that monitors plugi
 - **Multi-level alerts**: WARNING and CRITICAL severity levels
 - **Flexible operators**: Support for >, >=, <, <=, ==, != comparisons
 - **Hysteresis**: Prevents alert flapping with configurable recovery thresholds
-- **Smart notifications**: Alerts only on state changes, not every check
+- **Smart notifications**: Alerts only on state changes, not every check; de-escalations (e.g. CRITICAL → WARNING) do not generate a notification
 - **Re-notifications**: Periodic reminders for ongoing alerts
+- **Short-duration suppression**: Recovery notifications are suppressed for down events under 4 seconds (avoids noise from transient blips)
 - **Journal integration**: All threshold events logged for audit trail
+- **`ping_monitor` thresholds**: Latency and packet-loss thresholds use the same format as all other plugin metrics
 
 ### Configuration
 
@@ -172,7 +182,8 @@ thresholds:
       warning: 80.0      # Warn when CPU > 80%
       critical: 90.0     # Critical when CPU > 90%
       operator: ">"
-      hysteresis: 0.1    # 10% hysteresis to prevent flapping
+      hysteresis: 0.02   # 2% hysteresis to prevent flapping
+      display: "(threshold: {op_symbol} {threshold_value}%)"  # optional
   
   memory_monitor:
     percent:
@@ -214,7 +225,7 @@ thresholds:
     <hostname>:
       warning: <milliseconds>   # Warn when RTT > this value
       critical: <milliseconds>  # Critical when RTT > this value
-      hysteresis: 0.1           # Optional: 10% hysteresis (default)
+      hysteresis: 0.02          # Optional: 2% hysteresis (default)
 ```
 
 **Example alerts:**
@@ -265,7 +276,94 @@ All plugin metrics can be thresholded:
 - **Memory**: percent, available_mb, swap_percent
 - **Disk**: Per-partition percent, free_gb, free_mb
 - **Network**: errors_total, dropped packets, connection counts
-- **Nagios**: exit_code mapping (0=OK, 1=WARNING, 2=CRITICAL)
+- **Nagios**: Any field emitted by `nagios_runner` (`<name>_status_code`, `<name>_status`, `<name>_output`, performance data fields)
+
+### Display Format Templates
+
+Each threshold entry accepts an optional `display` field — a Python format string shown in notifications and on the Alerts dashboard:
+
+```yaml
+nagios_runner:
+  status_code:
+    warning: 1
+    critical: 2
+    operator: ">="
+    display: "{check_name}: exit {value} (expected < {threshold_value})"
+```
+
+Available variables:
+
+| Variable | Description |
+|---|---|
+| `{value}` | Current metric value |
+| `{threshold_value}` | Threshold that was crossed |
+| `{op_symbol}` | Comparison operator (`>`, `<`, `>=`, …); `"nagios"` for the nagios operator |
+| `{check_name}` | Prefix stripped by generic matching (see below) |
+| `{metric_name}` | Full field name within the plugin data |
+| `{output}` | For `nagios_runner` generic matches: the matched check's status text (alias for `{check_name}_output`) |
+| `{status}` | For `nagios_runner` generic matches: the matched check's status name — OK/WARNING/CRITICAL/UNKNOWN (alias for `{check_name}_status`) |
+| any plugin field | Any other field present in the plugin's data |
+
+### Generic Threshold Matching
+
+When a metric name has no exact threshold entry, the server progressively strips leading underscore-separated segments and re-tries the lookup. This lets a single generic entry cover an entire family of metrics.
+
+The classic use case is `nagios_runner`, which names each metric after the command that produced it:
+
+```
+nagios_runner.check_disk_root_status_code    → no exact match
+nagios_runner.disk_root_status_code          → no match
+nagios_runner.root_status_code               → no match
+nagios_runner.status_code                    → matched ✓
+```
+
+Configure the generic threshold once using the `nagios` operator, which maps exit codes directly to alert severity without requiring numeric warning/critical values:
+
+```yaml
+nagios_runner:
+  status_code:
+    operator: "nagios"   # 0=OK  1=WARNING  2=CRITICAL  3=UNKNOWN
+    display: "{check_name}: {output}"
+```
+
+The stripped prefix (`check_disk_root` in the example above) is available as `{check_name}` in the display template, so you can identify which check triggered the alert without writing a separate threshold entry per command.
+
+Exact matches always take priority. A generic entry only applies when no specific one is defined.
+
+### Per-Host Threshold Profiles
+
+Named threshold configurations let different hosts use different limits. A host's `threshold_config` can be a single name or a **list** — lists are applied left-to-right so profiles compose without duplication:
+
+```yaml
+threshold_configs:
+  default:
+    thresholds:
+      cpu_monitor:
+        cpu_percent: {warning: 80, critical: 90}
+      memory_monitor:
+        memory_percent: {warning: 85, critical: 95}
+
+  tight_cpu:           # override CPU limits only
+    thresholds:
+      cpu_monitor:
+        cpu_percent: {warning: 60, critical: 75}
+
+  db_disk:             # add a database partition check
+    thresholds:
+      disk_monitor:
+        partitions:
+          /var/lib/postgresql:
+            percent: {warning: 75, critical: 88}
+
+hosts:
+  web-01:
+    threshold_config: default          # single profile
+
+  db-01:
+    threshold_config: [tight_cpu, db_disk]   # layered: CPU override + extra disk check
+```
+
+Each named config's overrides are applied in order on top of the defaults. Metrics not mentioned in a profile are inherited unchanged.
 
 See [docs/THRESHOLD_ALERTING.md](docs/THRESHOLD_ALERTING.md) for comprehensive documentation including best practices, troubleshooting, and advanced configuration.
 
@@ -328,9 +426,10 @@ Heartbeat includes a built-in HTTP/WebSocket server that provides both a REST AP
 ### Web Dashboards
 
 - **Login** (`/login`): Browser login form (shown automatically when auth is configured)
-- **Live View** (`/live`): Real-time host connectivity, latency, and messages
+- **Live View** (`/live`): Real-time host connectivity, latency, and messages; hostnames link directly to the Host Overview page
-- **Plugin Metrics** (`/plugins`): Browse and visualize metrics from all plugins
+- **Host Overview** (`/plugins/<host>`): Per-host plugin metrics with ZFS pool visualization; filtered to hosts where the logged-in user is owner or manager (admins see all)
-- **Alerts Dashboard** (`/alerts`): Monitor active alerts with severity filtering
+- **Alerts Dashboard** (`/alerts`): Monitor active alerts with severity filtering; alert count pie chart shown in the navigation bar
+- **Settings** (`/settings`): Server configuration, user management, and threshold configuration viewer
 
 ### API Endpoints
 
@@ -416,12 +515,11 @@ You can also run it via the module entrypoint:
 python -m hbd.client.main your-server.example.com
 ```
 
-Client configuration can also be specified in YAML:
+Client configuration can also be specified in YAML (`~/.hbc.yaml`):
 
 ```yaml
-server: hbd.example.com
+hb_port: 50003        # Server port (default: 50003)
-port: 50003
+interval: 30          # Heartbeat interval in seconds
-interval: 30
 plugins:
   cpu_monitor:
     interval: 300      # Check every 5 minutes (default)
@@ -435,12 +533,20 @@ plugins:
   nagios_runner:
     interval: 300      # Check every 5 minutes (default)
     commands:
-      - /usr/lib/nagios/plugins/check_load -w 5,4,3 -c 10,8,6
+      - name: check_load
-      - /usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /
+        command: /usr/lib/nagios/plugins/check_load -w 5,4,3 -c 10,8,6
+      - name: check_disk
+        command: /usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /
 ```
 
+The server hostname is always passed as a positional command-line argument; there is no `server:` config key.
+
 All monitoring plugins default to 5-minute (300 second) intervals, but can be customized as needed.
 
+**Connection retry:** If a server is temporarily unreachable, `hbc` retries `open()` indefinitely on every heartbeat interval. IPv6 connections that never succeeded during early startup are dropped after 3 consecutive failures (to handle hosts without IPv6 routing), while IPv4 connections always retry.
+
+**Daemon logging:** When running with `-d`, `hbc` routes all log output to syslog (`LOG_DAEMON` facility) after daemonizing. Without `-d`, logs go to stderr as usual.
+
 ### hbc_mini — single-file client (no external dependencies)
 
 `scripts/hbc_mini.py` is a self-contained version of the heartbeat client that requires only Python 3.8+ and no external packages. Copy it to any host and run it directly — no virtualenv, no `pip install`.
@@ -496,8 +602,10 @@ python3 hbc_mini.py -m "maintenance starting" your-server.example.com
 
 - No YAML config (use JSON instead)
 - No `filesystem_info` plugin
+- No `zfs_monitor` plugin (requires `zpool(8)` and the full plugin loader)
 - `cpu_monitor` does not report per-core usage or CPU frequency (no psutil)
 - Plugins cannot be loaded from external `.py` files — all plugins are compiled in
+- No IPv6 early-fail protection — connections that fail to open at startup are silently skipped rather than retried
 
 Everything else — heartbeat protocol, ACK/CMD/UPD handling, `hb_install.sh`-based self-update, daemonize, syslog — is identical to the full client.
 

docs/NAGIOS_INTEGRATION.md

@@ -104,11 +104,6 @@ The `nagios_runner` plugin collects:
 - `{name}_{metric}_min` - Minimum value (if present)
 - `{name}_{metric}_max` - Maximum value (if present)
 
-**Overall:**
-- `overall_status` - Worst status from all commands
-- `overall_status_code` - Worst status code
-- `plugin_count` - Number of Nagios plugins executed
-
 ## Configuration Options
 
 ```yaml

docs/THRESHOLD_ALERTING.md

@@ -814,34 +814,32 @@ Planned features:
 
 ## Multi-Threshold Configuration
 
-**New in version 2.0**: Support for multiple named threshold configurations with per-host mapping.
+Support for multiple named threshold configurations with per-host mapping and composable layering.
 
 ### Overview
 
 The multi-threshold feature allows you to:
-- Define multiple sets of threshold configurations
+- Define multiple named threshold configurations
-- Map different hosts to different threshold sets
+- Assign one or more configurations to each host
+- Compose configurations by layering — each named config's overrides are applied in order on top of the defaults
 - Use different sensitivity levels for different environments
-- Maintain a default configuration for unmapped hosts
 
 ### Configuration Structure
 
+Named configurations are defined under `threshold_configs`. Each host selects which ones to use via `threshold_config` in the `hosts` section (a string for a single config, or a list to layer multiple):
+
 ```yaml
-# Optional: Set the default configuration name (defaults to "default")
+# Optional: set the default configuration name (defaults to "default")
 default_threshold_config: "default"
 
-# Define multiple named threshold configurations
 threshold_configs:
-  # Configuration name 1
   default:
     thresholds:
-      # Standard threshold definitions
       cpu_monitor:
         cpu_percent:
           warning: 80.0
           critical: 90.0
 
-  # Configuration name 2
   high_sensitivity:
     thresholds:
       cpu_monitor:
@@ -849,7 +847,6 @@ threshold_configs:
           warning: 60.0
           critical: 75.0
 
-  # Configuration name 3
   low_sensitivity:
     thresholds:
       cpu_monitor:
@@ -857,14 +854,77 @@ threshold_configs:
           warning: 90.0
           critical: 95.0
 
-# Map specific hosts to specific configurations
+hosts:
-host_threshold_mapping:
+  prod-web-01:
-  prod-web-01: high_sensitivity
+    threshold_config: high_sensitivity   # single config
-  prod-web-02: high_sensitivity
+
-  dev-server-01: low_sensitivity
+  dev-server-01:
-  # Unmapped hosts use default_threshold_config
+    threshold_config: low_sensitivity
+
+  # Hosts with no threshold_config use default_threshold_config
 ```
 
+### Composable Configurations (list form)
+
+`threshold_config` can be a list. Configs are applied **left to right**: the defaults are the base, then each named config's overrides are layered on top. Later entries in the list win on any metric they define.
+
+```yaml
+threshold_configs:
+  default:
+    thresholds:
+      cpu_monitor:
+        cpu_percent: {warning: 80, critical: 90}
+      memory_monitor:
+        memory_percent: {warning: 85, critical: 95}
+      disk_monitor:
+        partitions:
+          /:
+            percent: {warning: 80, critical: 90}
+
+  # Tighter CPU limits for busy servers
+  high_cpu_load:
+    thresholds:
+      cpu_monitor:
+        cpu_percent: {warning: 60, critical: 75}
+
+  # Tighter disk limits for data-heavy servers
+  busy_disk:
+    thresholds:
+      disk_monitor:
+        partitions:
+          /:
+            percent: {warning: 70, critical: 85}
+
+hosts:
+  # Gets default thresholds only
+  web-01:
+    threshold_config: default
+
+  # Gets tighter CPU limits, default memory and disk
+  build-server:
+    threshold_config: high_cpu_load
+
+  # Layers both: tighter CPU AND tighter disk, default memory
+  db-01:
+    threshold_config: [high_cpu_load, busy_disk]
+
+  # Three layers: busy_disk overrides high_cpu_load if they conflict
+  storage-01:
+    threshold_config: [default, high_cpu_load, busy_disk]
+```
+
+**How layering works:**
+
+Starting from the `default` thresholds:
+
+| Layer | Applied config | Effect |
+|-------|---------------|--------|
+| Base  | `default` | all default thresholds |
+| +1    | `high_cpu_load` | cpu_percent overridden to 60/75 |
+| +2    | `busy_disk` | disk percent overridden to 70/85; cpu_percent stays at 60/75 |
+
+Each named config only overrides the metrics it explicitly defines. Metrics not mentioned in a config inherit from the layers beneath.
+
 ### Use Cases
 
 #### 1. Environment-Based Thresholds
@@ -887,11 +947,15 @@ threshold_configs:
           warning: 90.0   # More relaxed for dev
           critical: 98.0
 
-host_threshold_mapping:
+hosts:
-  prod-web-01: production
+  prod-web-01:
-  prod-web-02: production
+    threshold_config: production
-  dev-web-01: development
+  prod-web-02:
-  dev-web-02: development
+    threshold_config: production
+  dev-web-01:
+    threshold_config: development
+  dev-web-02:
+    threshold_config: development
 ```
 
 #### 2. Server Role-Based Thresholds
@@ -914,7 +978,7 @@ threshold_configs:
           warning: 70.0
           critical: 85.0
       memory_monitor:
-        percent:
+        memory_percent:
           warning: 90.0   # Databases can use high memory
           critical: 97.0
       disk_monitor:
@@ -927,17 +991,23 @@ threshold_configs:
   cache:
     thresholds:
       memory_monitor:
-        percent:
+        memory_percent:
           warning: 95.0   # Redis/Memcached can use very high memory
           critical: 99.0
 
-host_threshold_mapping:
+hosts:
-  web-01: webserver
+  web-01:
-  web-02: webserver
+    threshold_config: webserver
-  db-01: database
+  web-02:
-  db-02: database
+    threshold_config: webserver
-  redis-01: cache
+  db-01:
-  memcached-01: cache
+    threshold_config: database
+  db-02:
+    threshold_config: database
+  redis-01:
+    threshold_config: cache
+  memcached-01:
+    threshold_config: cache
 ```
 
 #### 3. Sensitivity Levels
@@ -952,7 +1022,7 @@ threshold_configs:
         partitions:
           /:
             percent:
-              warning: 70.0    # Very sensitive
+              warning: 70.0
               critical: 80.0
               hysteresis: 0.15
 
@@ -976,52 +1046,91 @@ threshold_configs:
               critical: 98.0
               hysteresis: 0.05
 
-host_threshold_mapping:
+hosts:
-  payment-gateway: critical
+  payment-gateway:
-  auth-server: critical
+    threshold_config: critical
-  web-01: standard
+  auth-server:
-  web-02: standard
+    threshold_config: critical
-  test-server: relaxed
+  web-01:
+    threshold_config: standard
+  web-02:
+    threshold_config: standard
+  test-server:
+    threshold_config: relaxed
 ```
 
-### Backward Compatibility
+#### 4. Composable Profiles
 
-The legacy single threshold configuration is fully supported:
+Build host-specific thresholds by combining small, focused configs:
 
 ```yaml
-# Old format - still works
-thresholds:
-  cpu_monitor:
-    cpu_percent:
-      warning: 80.0
-      critical: 90.0
-```
-
-This is equivalent to:
-
-```yaml
-# New format
 threshold_configs:
+  # Baseline — everything at default levels
   default:
     thresholds:
       cpu_monitor:
-        cpu_percent:
+        cpu_percent: {warning: 80, critical: 90}
-          warning: 80.0
+      memory_monitor:
-          critical: 90.0
+        memory_percent: {warning: 85, critical: 95}
-```
 
+  # Overlay: tighter CPU only
+  tight_cpu:
+    thresholds:
+      cpu_monitor:
+        cpu_percent: {warning: 60, critical: 75}
+
+  # Overlay: tighter memory only
+  tight_memory:
+    thresholds:
+      memory_monitor:
+        memory_percent: {warning: 70, critical: 85}
+
+  # Overlay: extra disk partition for database servers
+  db_disk:
+    thresholds:
+      disk_monitor:
+        partitions:
+          /var/lib/postgresql:
+            percent: {warning: 75, critical: 88}
+
+hosts:
+  # Plain web server
+  web-01:
+    threshold_config: default
+
+  # Build server: tight CPU, default memory and disk
+  build-01:
+    threshold_config: tight_cpu
+
+  # Database: tight CPU + tight memory + extra disk partition
+  db-01:
+    threshold_config: [tight_cpu, tight_memory, db_disk]
+
+  # Replica database: tight memory + extra disk, normal CPU
+  db-02:
+    threshold_config: [tight_memory, db_disk]
+```
 ### Configuration Priority
 
-1. **Host-specific mapping**: If host is in `host_threshold_mapping`, use that config
+1. **Host `threshold_config` (list)**: Layer each named config's overrides left-to-right on top of the defaults
-2. **Default config**: Use `default_threshold_config` 
+2. **Host `threshold_config` (string)**: Use that single named config directly
-3. **First alphabetically**: If default not found, use first config alphabetically
+3. **`host_threshold_mapping`** (legacy): Same as above, string only
-4. **Legacy fallback**: If `threshold_configs` not present, use `thresholds`
+4. **`default_threshold_config`**: Used for hosts with no mapping
+5. **First alphabetically**: If the default config is not found, use the first config alphabetically
+6. **Legacy `thresholds` section**: Used when `threshold_configs` is absent entirely
 
-### Example: Complete Multi-Threshold Setup
+### Backward Compatibility
 
-See `hbd/config_multi_threshold_example.yaml` for a complete example with:
+The legacy `host_threshold_mapping` top-level key and the flat `thresholds` section are still fully supported:
-- 4 named configurations (default, high_sensitivity, low_sensitivity, database)
+
-- Host-to-config mappings for production, development, and test systems
+```yaml
-- Specialized database server thresholds
+# Still works — equivalent to hosts: {prod-web-01: {threshold_config: high_sensitivity}}
-- Custom display messages with plugin data
+host_threshold_mapping:
+  prod-web-01: high_sensitivity
+
+# Still works — equivalent to threshold_configs: {default: {thresholds: ...}}
+thresholds:
+  cpu_monitor:
+    cpu_percent: {warning: 80, critical: 90}
+```
 

hbd/__init__.py

@@ -14,4 +14,4 @@ Install options:
 """
 
 __all__ = ["__version__"]
-__version__ = "5.1.12"
+__version__ = "5.2.0"

hbd/client/main.py

@@ -56,6 +56,8 @@ class AsyncConnection:
         self.transport: Optional[asyncio.DatagramTransport] = None
         self.protocol: Optional[asyncio.DatagramProtocol] = None
         self._dead = False
+        self._ever_opened = False
+        self._open_fail_count = 0   # consecutive failures before first success
 
         self.logger = logging.getLogger(f"hbc.conn.{addr}")
 
@@ -73,6 +75,7 @@ class AsyncConnection:
                 lambda: HeartbeatProtocol(self),
                 family=self.af
             )
+            self._ever_opened = True
             self.logger.debug(f"Opened connection to {self.addr}:{self.port}")
             return True
         except Exception as e:
@@ -262,15 +265,51 @@ async def handle_update(conn: AsyncConnection, _msg: dict):  # pyright: ignore[r
 
 
 async def heartbeat_sender(conn: AsyncConnection, interval: int):
-    """Send periodic heartbeats.
+    """Send periodic heartbeats, retrying the connection if it is not open.
+
+    IPv6 connections that fail to open before their first successful send are
+    dropped after IPV6_EARLY_FAIL_LIMIT attempts so that a network without IPv6
+    does not keep a dead sender alive.  IPv4 connections are retried indefinitely.
 
     Args:
         conn: Connection to send on
         interval: Heartbeat interval in seconds
     """
     logger = logging.getLogger("hbc.heartbeat")
+    IPV6_EARLY_FAIL_LIMIT = 3
+
+    while running and not conn._dead:
+        # Ensure transport is open before attempting to send.
+        if not conn.transport:
+            opened = await conn.open()
+            if opened:
+                conn._open_fail_count = 0
+            else:
+                conn._open_fail_count += 1
+                # Drop an IPv6 connection that has never come up within the
+                # first few attempts — it is likely unavailable on this network.
+                if (not conn._ever_opened
+                        and conn.af == socket.AF_INET6
+                        and conn._open_fail_count >= IPV6_EARLY_FAIL_LIMIT):
+                    logger.warning(
+                        f"IPv6 connection to {conn.addr} unreachable after "
+                        f"{conn._open_fail_count} attempts, disabling"
+                    )
+                    conn._dead = True
+                    break
+                # Retry after the normal interval; IPv4 retries forever.
+                try:
+                    if shutdown_event:
+                        await asyncio.wait_for(shutdown_event.wait(), timeout=interval)
+                        break
+                    else:
+                        await asyncio.sleep(interval)
+                except asyncio.TimeoutError:
+                    pass
+                except asyncio.CancelledError:
+                    raise
+                continue
 
-    while running:
         try:
             msg = {
                 "acks": conn.ackcount,
@@ -279,19 +318,16 @@ async def heartbeat_sender(conn: AsyncConnection, interval: int):
             }
             await conn.sendto(msg, "HTB")
 
-        except Exception as e:
-            logger.error(f"Error sending heartbeat: {e}", exc_info=True)
         except asyncio.CancelledError:
             logger.debug("Heartbeat sender cancelled")
             raise
+        except Exception as e:
+            logger.error(f"Error sending heartbeat: {e}", exc_info=True)
 
         # Wait for next interval or shutdown event
         try:
             if shutdown_event:
-                await asyncio.wait_for(
+                await asyncio.wait_for(shutdown_event.wait(), timeout=interval)
-                    shutdown_event.wait(), 
-                    timeout=interval
-                )
                 break
             else:
                 await asyncio.sleep(interval)
@@ -427,16 +463,13 @@ async def cleanup(connections: List[AsyncConnection]):
     logger = logging.getLogger("hbc.cleanup")
     logger.info("Cleaning up connections")
     
-    for conn in connections:
+    target = next((c for c in connections if c.transport), connections[0] if connections else None)
+    if target:
         try:
-            msg = {
+            await target.sendto({"shutdown": 1, "acks": target.ackcount})
-                "shutdown": 1,
-                "acks": conn.ackcount
-            }
-            await conn.sendto(msg)
         except Exception as e:
             logger.error(f"Error sending shutdown: {e}")
-        
+    for conn in connections:
         conn.close()
     
     # Give messages time to send
@@ -481,12 +514,13 @@ async def async_main(args, config):
             addr = addr_info[4][0]
 
             conn = AsyncConnection(conn_id, addr, hb_port, af, iam)
-            if await conn.open():
+            if not await conn.open():
+                logger.warning(f"Initial open to {addr} failed, heartbeat sender will retry")
             connections.append(conn)
             conn_id += 1
 
     if not connections:
-        logger.error("No connections established")
+        logger.error("No connections established (DNS resolution failed for all hosts)")
         return 1
     
     logger.info(f"Created {len(connections)} connections")
@@ -501,8 +535,8 @@ async def async_main(args, config):
             boot_msg["msg"] = args.message
         
         boot_msg["acks"] = 0
-        for conn in connections:
+        target = next((c for c in connections if c.transport), connections[0])
-            await conn.sendto(boot_msg)
+        await target.sendto(boot_msg)
         
         if args.message and not args.daemon:
             # Message-only mode
@@ -525,6 +559,13 @@ async def async_main(args, config):
     for sig in (signal.SIGTERM, signal.SIGINT):
         loop.add_signal_handler(sig, stop)
 
+    def _sighup():
+        global dorestart
+        dorestart = True
+        stop()
+
+    loop.add_signal_handler(signal.SIGHUP, _sighup)
+    
     # Start async tasks
     # Heartbeat senders (one per connection)
     for conn in connections:
@@ -695,7 +736,7 @@ def main(argv=None):
     
     # Daemonize if requested
     if args.daemon:
-        print("Daemonizing...")
+        logging.info("Daemonizing...")
         daemonize()
         _reconfigure_logging_for_daemon(log_level)
         logging.info(f"hbc starting, sending heartbeat to {', '.join(args.hosts)}")

hbd/client/plugins/cpu_monitor.py

@@ -119,6 +119,13 @@ class CPUMonitorPlugin(MonitorPlugin):
             except Exception as e:
                 self.logger.debug(f"Could not get CPU times: {e}")
 
+            # Uptime in seconds
+            try:
+                import time
+                data["uptime_seconds"] = int(time.time() - self.psutil.boot_time())
+            except Exception as e:
+                self.logger.debug(f"Could not get uptime: {e}")
+            
             self.logger.debug(
                 f"Collected CPU metrics: {data.get('cpu_percent', 'N/A')}% usage"
             )

hbd/client/plugins/memory_monitor.py

@@ -14,6 +14,24 @@ except ImportError:
 
 from hbd.client.plugin import MonitorPlugin
 
+
+def _zfs_arc_bytes() -> int:
+    """Return current ZFS ARC size in bytes, or 0 if ZFS is not present.
+
+    ZFS ARC is reclaimable but is not included in MemAvailable by the Linux
+    kernel (it is not in SReclaimable), so it would otherwise be counted as
+    used memory.
+    """
+    try:
+        with open("/proc/spl/kstat/zfs/arcstats") as fh:
+            for line in fh:
+                parts = line.split()
+                if len(parts) >= 3 and parts[0] == "size":
+                    return int(parts[2])
+    except (OSError, ValueError):
+        pass
+    return 0
+
 logger = logging.getLogger(__name__)
 
 
@@ -101,11 +119,21 @@ class MemoryMonitorPlugin(MonitorPlugin):
         
         # Virtual (physical) memory statistics
         vmem = psutil.virtual_memory()
+
+        # psutil's available already excludes page cache / file buffers
+        # (uses MemAvailable on Linux). Add ZFS ARC on top because the kernel
+        # does not include it in SReclaimable / MemAvailable even though it is
+        # reclaimable.
+        arc_bytes = _zfs_arc_bytes()
+        available = min(vmem.available + arc_bytes, vmem.total)
+        used = vmem.total - available
+        percent = round(used / vmem.total * 100, 1) if vmem.total else 0.0
+
         metrics['memory_total'] = vmem.total
-        metrics['memory_available'] = vmem.available
+        metrics['memory_available'] = available
-        metrics['memory_used'] = vmem.used
+        metrics['memory_used'] = used
         metrics['memory_free'] = vmem.free
-        metrics['memory_percent'] = vmem.percent
+        metrics['memory_percent'] = percent
         
         # Platform-specific memory details
         if hasattr(vmem, 'active'):

hbd/client/plugins/nagios_runner.py

@@ -31,16 +31,13 @@ from hbd.client.plugin import MonitorPlugin
 
 
 # Nagios exit codes
-NAGIOS_OK = 0
-NAGIOS_WARNING = 1
-NAGIOS_CRITICAL = 2
 NAGIOS_UNKNOWN = 3
 
 STATUS_NAMES = {
-    NAGIOS_OK: "OK",
+    0: "OK",
-    NAGIOS_WARNING: "WARNING",
+    1: "WARNING",
-    NAGIOS_CRITICAL: "CRITICAL",
+    2: "CRITICAL",
-    NAGIOS_UNKNOWN: "UNKNOWN"
+    3: "UNKNOWN",
 }
 
 
@@ -129,9 +126,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
         """
         results = {}
 
-        # Track overall status (worst status wins)
-        worst_status = NAGIOS_OK
-        
         for cmd_config in self.commands:
             name = cmd_config.get("name")
             command = cmd_config.get("command")
@@ -149,10 +143,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
                 results[f"{name}_status_code"] = status_code
                 results[f"{name}_output"] = output
 
-                # Track worst status
-                if status_code > worst_status:
-                    worst_status = status_code
-                
                 # Parse and add performance data
                 if perfdata:
                     for metric_name, metric_value in perfdata.items():
@@ -167,12 +157,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
                 results[f"{name}_status"] = "ERROR"
                 results[f"{name}_status_code"] = NAGIOS_UNKNOWN
                 results[f"{name}_output"] = str(e)
-                worst_status = NAGIOS_UNKNOWN
-        
-        # Add overall status
-        results["overall_status"] = STATUS_NAMES.get(worst_status, "UNKNOWN")
-        results["overall_status_code"] = worst_status
-        results["plugin_count"] = len(self.commands)
 
         return results
     

hbd/client/plugins/zfs_monitor.py

@@ -0,0 +1,130 @@
+"""
+ZFS pool monitoring plugin for Heartbeat.
+
+Collects per-pool health, capacity, and cumulative I/O statistics via zpool(8).
+"""
+
+import asyncio
+import logging
+import shutil
+from typing import Any, Dict, List, Optional
+
+from hbd.client.plugin import MonitorPlugin
+
+logger = logging.getLogger(__name__)
+
+
+def _int(s: str) -> Optional[int]:
+    try:
+        return int(s.strip().rstrip("KMGTkBkmgt%x"))
+    except (ValueError, AttributeError):
+        return None
+
+
+def _float(s: str) -> Optional[float]:
+    try:
+        return float(s.strip().rstrip("%x"))
+    except (ValueError, AttributeError):
+        return None
+
+
+class ZFSMonitorPlugin(MonitorPlugin):
+    """Monitor ZFS pool health, capacity, and I/O statistics.
+
+    Collects per pool:
+    - health: ONLINE, DEGRADED, FAULTED, etc.
+    - size / alloc / free: total, allocated and free bytes
+    - capacity: percentage used (0-100)
+    - frag: fragmentation percentage
+    - dedup: deduplication ratio
+    - read_ops / write_ops: cumulative I/O operations since last boot/clear
+    - read_bw / write_bw: cumulative bytes transferred since last boot/clear
+
+    Configuration:
+        interval: collection interval in seconds (default: 300)
+        pools: list of pool names to monitor (default: all)
+    """
+
+    name = "zfs_monitor"
+    description = "ZFS pool health, capacity, and I/O statistics"
+    interval = 300
+
+    def __init__(self, config: Optional[Dict[str, Any]] = None):
+        super().__init__(config)
+        self.interval = self.config.get("interval", 300)
+        self._pools_filter: Optional[List[str]] = self.config.get("pools", None)
+
+    async def initialize(self) -> bool:
+        if not shutil.which("zpool"):
+            self.skip_reason = "zpool not found"
+            return False
+        logger.info("ZFS monitor initialized (interval: %ds)", self.interval)
+        return True
+
+    async def _run(self, *args: str) -> List[str]:
+        """Run a command and return its stdout lines, or [] on error."""
+        try:
+            proc = await asyncio.create_subprocess_exec(
+                *args,
+                stdout=asyncio.subprocess.PIPE,
+                stderr=asyncio.subprocess.DEVNULL,
+            )
+            stdout, _ = await asyncio.wait_for(proc.communicate(), timeout=15)
+            return stdout.decode(errors="replace").splitlines()
+        except (FileNotFoundError, asyncio.TimeoutError) as exc:
+            logger.warning("zfs_monitor: %s: %s", args[0], exc)
+            return []
+
+    async def _zpool_list(self) -> Dict[str, Dict]:
+        """Return per-pool health and capacity from `zpool list`."""
+        lines = await self._run(
+            "zpool", "list", "-H", "-p",
+            "-o", "name,health,size,alloc,free,cap,frag,dedup",
+        )
+        pools: Dict[str, Dict] = {}
+        for line in lines:
+            parts = line.split("\t")
+            if len(parts) < 8:
+                continue
+            name = parts[0].strip()
+            if self._pools_filter and name not in self._pools_filter:
+                continue
+            pools[name] = {
+                "health":   parts[1].strip(),
+                "size":     _int(parts[2]),
+                "alloc":    _int(parts[3]),
+                "free":     _int(parts[4]),
+                "capacity": _float(parts[5]),
+                "frag":     _float(parts[6]),
+                "dedup":    _float(parts[7]),
+            }
+        return pools
+
+    async def _zpool_iostat(self) -> Dict[str, Dict]:
+        """Return per-pool cumulative I/O counters from `zpool iostat`."""
+        lines = await self._run("zpool", "iostat", "-H", "-p")
+        io: Dict[str, Dict] = {}
+        for line in lines:
+            parts = line.split("\t")
+            if len(parts) < 7:
+                continue
+            name = parts[0].strip()
+            if not name or name.startswith(" "):
+                continue
+            io[name] = {
+                "read_ops": _int(parts[3]),
+                "write_ops": _int(parts[4]),
+                "read_bw":  _int(parts[5]),
+                "write_bw": _int(parts[6]),
+            }
+        return io
+
+    async def _collect_metrics(self) -> Dict[str, Any]:
+        pools, io = await asyncio.gather(self._zpool_list(), self._zpool_iostat())
+        for name, stats in io.items():
+            if name in pools:
+                pools[name].update(stats)
+        return {"pools": pools}
+
+
+plugin = ZFSMonitorPlugin

hbd/server/config.py

@@ -95,6 +95,12 @@ THRESHOLD_DEFAULTS = {
                 'warning': 200,
                 'critical': 250.0,
                 'count': 3  # Optional: number of consecutive breaches before alerting
+            },
+            'nagios_runner': {
+                'status_code': {
+                    'display': '{check_name} {output}',
+                    'operator': "nagios"
+                }   
             }
         }
     }
@@ -225,7 +231,7 @@ def get_watchhosts(config):
     hosts_config = config.get("hosts", {})
     if isinstance(hosts_config, dict):
         for host_name, host_attrs in hosts_config.items():
-            if isinstance(host_attrs, dict) and host_attrs.get("watch", False):
+            if isinstance(host_attrs, dict) and host_attrs.get("watch", True):
                 watchhosts.append(host_name)
     return watchhosts
 

hbd/server/hbdclass.py

@@ -95,7 +95,7 @@ class Connection:
         if not Null:
             d["addr"] = self.addr
             if self.rtts[-1]:
-                d["rtt"] = "%0.1f" % self.rtts[-1]
+                d["rtt"] = "%d" % round(self.rtts[-1])
             elif self.state == Connection.UNKNOWN:
                 d["rtt"] = ""
             else:
@@ -286,7 +286,7 @@ class Host:
             Host.hosts[name] = self
         self.num = num
         self.dyn = False
-        self.watched = False
+        self.watched = True
         self.upcount = 0
         self.interval = 0
         self.doesack = -1
@@ -304,6 +304,7 @@ class Host:
 
     def statedict(self):
         d = {}
+        d["raw_name"] = self.name
         d["name"] = self.name
         if self.dyn:
             d["name"] += "*"

hbd/server/http.py

@@ -154,6 +154,25 @@ async def start(
         lst = [h.jsons() for h in hosts]
         return web.json_response(json.loads("[" + ",".join(lst) + "]"))
 
+    async def api_alert_summary(request):
+        """GET /api/0/alert_summary — counts of ok/warning/critical hosts visible to caller."""
+        user, err = _require_auth(request)
+        if err:
+            return err
+        from .threshold import AlertLevel
+        critical = warning = ok = 0
+        for host in hbdclass.Host.hosts.values():
+            if not _can_operate_host(user, host):
+                continue
+            levels = {s.level for s in host.alert_states.values()}
+            if AlertLevel.CRITICAL in levels:
+                critical += 1
+            elif AlertLevel.WARNING in levels:
+                warning += 1
+            else:
+                ok += 1
+        return web.json_response({"critical": critical, "warning": warning, "ok": ok})
+
     async def api_messages(request):
         lst = data.msgs[-30:]
         return web.json_response(lst)
@@ -258,7 +277,9 @@ async def start(
             extra_scripts=extra_scripts,
             hbd_version=hbd_version,
             hosts=[
-                hbdclass.Host.hosts[h].stateinfo() for h in sorted(hbdclass.Host.hosts)
+                hbdclass.Host.hosts[h].stateinfo()
+                for h in sorted(hbdclass.Host.hosts)
+                if _can_operate_host(current_user, hbdclass.Host.hosts[h])
             ],
             messages=data.msgs[-30:],
             current_user=current_user.to_dict() if current_user else None,
@@ -510,12 +531,13 @@ async def start(
         hosts_with_plugins = []
         for hostname in sorted(hbdclass.Host.hosts.keys()):
             host = hbdclass.Host.hosts[hostname]
-            if not _can_view_host(current_user, host):
+            if not _can_operate_host(current_user, host):
                 continue
             if host.plugin_data:
                 hosts_with_plugins.append({
                     "name": hostname,
                     "plugins": list(host.plugin_data.keys()),
+                    "is_owner": _can_own_host(current_user, host),
                 })
 
         tmpl = env.get_template("plugins.html")
@@ -868,7 +890,7 @@ async def start(
         tmpl = env.get_template("settings.html")
         body = tmpl.render(
             title="Settings - Heartbeat",
-            sections=settings_mod.get_settings_sections(config),
+            sections=settings_mod.get_settings_sections(config, threshold_checker=threshold_checker),
             current_user=current_user.to_dict() if current_user else None,
             active_page="settings",
         )
@@ -891,6 +913,7 @@ async def start(
             web.get("/api/0/users/{username}/avatar", api_user_avatar),
             # Hosts
             web.get("/api/0/hosts", api_hosts),
+            web.get("/api/0/alert_summary", api_alert_summary),
             web.get("/api/0/messages", api_messages),
             web.get("/api/0/hosts/{hostname}/plugins", api_host_plugins),
             web.get("/api/0/hosts/{hostname}/plugins/{plugin_name}", api_host_plugin_detail),

hbd/server/main.py

@@ -101,9 +101,10 @@ async def reload_configuration(config_obj, config_path, components):
             access = config_mod.get_host_access(new_config, hostname)
             host.apply_access(access["owner"], access["managers"], access["monitors"])
 
-        # Reload threshold checker
+        # Reload threshold checker and prune alerts orphaned by the new config
         if 'threshold_checker' in components:
             components['threshold_checker'].reload(new_config)
+            components['threshold_checker'].purge_stale_alerts(hbdclass)
         
         # Note: Changes to the following require restart:
         # - hb_port, hbd_port, ws_port (already bound)
@@ -241,6 +242,10 @@ async def _run_async(config, config_path=None):
     )
     udp.restore_connection_timers(hbdclass, restore_ctx)
 
+    # Drop alert states that no longer have a matching threshold (stale after
+    # upgrade or config change between runs).
+    threshold_checker.purge_stale_alerts(hbdclass)
+
     # HTTP server (asyncio-based via aiohttp)
     try:
         http_task = asyncio.create_task(
@@ -250,6 +255,7 @@ async def _run_async(config, config_path=None):
                 config=config,
                 hbdclass=hbdclass,
                 tcss=None,
+                threshold_checker=threshold_checker,
                 verbose=config.get("verbose", False),
                 get_now=lambda: time.time(),
                 VER="",

hbd/server/settings.py

@@ -24,7 +24,7 @@ sensitive   bool  True when the raw value must never be shown
 # Credential field names that should always be masked.
 _SECRET_KEYS = frozenset({
     "password", "token", "user_key", "api_key", "secret",
-    "smtp_password", "smtp_user",
+    "smtp_password", "smtp_user", "api_password", "access_token",
 })
 
 _CHANNEL_TYPE_LABELS = {
@@ -88,7 +88,7 @@ def _sanitize_channel(name, cfg):
 # Public API
 # ---------------------------------------------------------------------------
 
-def get_settings_sections(config: dict) -> list:
+def get_settings_sections(config: dict, threshold_checker=None) -> list:
     """Return ordered list of setting sections for the settings page.
 
     Each section:
@@ -181,6 +181,41 @@ def get_settings_sections(config: dict) -> list:
             "notification_channels": attrs.get("notification_channels", []),
         })
 
+    # ---- Threshold configurations -----------------------------------------
+    def _tc_to_row(tc):
+        return {
+            "metric": tc.metric_path,
+            "operator": tc.operator.value,
+            "warning": tc.warning,
+            "critical": tc.critical,
+            "hysteresis": tc.hysteresis,
+            "count": tc.count,
+            "enabled": tc.enabled,
+        }
+
+    threshold_config_list = []
+    if threshold_checker is not None:
+        if threshold_checker.threshold_configs:
+            for cfg_name, cfg_metrics in sorted(threshold_checker.threshold_configs.items()):
+                # For the default config use the merged effective set;
+                # for named overrides use only the explicitly defined metrics
+                # (threshold_raw_configs) so inherited defaults are not repeated.
+                if cfg_name == "default":
+                    display_metrics = cfg_metrics
+                else:
+                    display_metrics = threshold_checker.threshold_raw_configs.get(cfg_name, cfg_metrics)
+                metrics = sorted(
+                    [_tc_to_row(tc) for tc in display_metrics.values()],
+                    key=lambda m: m["metric"],
+                )
+                threshold_config_list.append({"name": cfg_name, "metrics": metrics})
+        elif threshold_checker.thresholds:
+            metrics = sorted(
+                [_tc_to_row(tc) for tc in threshold_checker.thresholds.values()],
+                key=lambda m: m["metric"],
+            )
+            threshold_config_list.append({"name": "default", "metrics": metrics})
+
     # ---- Hosts summary ----------------------------------------------------
     hosts_list = []
     for hname, hcfg in (config.get("hosts") or {}).items():
@@ -188,7 +223,7 @@ def get_settings_sections(config: dict) -> list:
             continue
         hosts_list.append({
             "name": hname,
-            "watch": bool(hcfg.get("watch", False)),
+            "watch": bool(hcfg.get("watch", True)),
             "dyndns": bool(hcfg.get("dyndns", False)),
             "owner": hcfg.get("owner", ""),
             "managers": hcfg.get("managers", []),
@@ -312,6 +347,16 @@ def get_settings_sections(config: dict) -> list:
             "hosts": hosts_list,
             "fields": [],
         },
+        {
+            "id": "thresholds",
+            "title": "Threshold Configurations",
+            "description": "Named alert threshold sets. Each defines warning/critical levels per metric.",
+            "threshold_configs": threshold_config_list,
+            "fields": [
+                field("default_threshold_config", "Default config", "text",
+                      "Threshold config used for hosts with no explicit mapping."),
+            ],
+        },
         {
             "id": "runtime",
             "title": "Runtime",

hbd/server/templates/alerts.html

@@ -4,6 +4,11 @@
 
   <style>
 
+    html, body {
+      height: auto;
+      overflow-y: auto;
+    }
+
     .container {
       max-width: 1400px;
       margin: 0 auto;
@@ -170,8 +175,12 @@
 
     .alert-hostname {
       font-weight: bold;
-      color: #333;
+      color: #0066cc;
       font-size: 1.1em;
+      text-decoration: none;
+    }
+    .alert-hostname:hover {
+      text-decoration: underline;
     }
 
     .alert-metric {
@@ -400,6 +409,10 @@
         } else if (alert.threshold_value !== undefined && alert.threshold_value !== null && alert.operator) {
           valueText += ` <span class="threshold-info">(threshold: ${alert.operator} ${formatValue(alert.threshold_value)})</span>`;
         }
+        if (alert.recovery_threshold !== undefined && alert.recovery_threshold !== null) {
+          const recOp = (alert.operator === '>' || alert.operator === '>=') ? '<' : '>';
+          valueText += ` <span class="threshold-info" style="color:#888">(recovers ${recOp} ${formatValue(alert.recovery_threshold)})</span>`;
+        }
         
         // Build actions section
         let actionsHtml = '';
@@ -424,7 +437,7 @@
             <div class="alert-main">
               <div class="alert-header">
                 <span class="alert-level ${level}">${alert.level}</span>
-                <span class="alert-hostname">${alert.hostname}</span>
+                <a class="alert-hostname" href="/plugins#${alert.hostname}">${alert.hostname}</a>
               </div>
               <div class="alert-metric">${alert.metric_path}</div>
               <div class="alert-details">

hbd/server/templates/head.html

@@ -126,11 +126,17 @@
       }
 
       /* Swiss railway clock — nav */
-      .nav-clock {
+      .nav-pie {
         flex-shrink: 0;
         line-height: 0;
         margin-left: auto;
         padding: 4px 4px 4px 0;
+      }
+      #alert-pie { display: block; cursor: default; }
+      .nav-clock {
+        flex-shrink: 0;
+        line-height: 0;
+        padding: 4px 4px 4px 0;
         cursor: pointer;
       }
       #swiss-clock { display: block; }

hbd/server/templates/live.html

@@ -236,6 +236,8 @@
       color: #ff9800;
       font-weight: 700;
     }
+    #ntable a.host-link { color: inherit; text-decoration: none; }
+    #ntable a.host-link:hover { text-decoration: underline; }
   </style>
   <script type="text/javascript">
     var cnt = 0;
@@ -245,11 +247,13 @@
     var HBD_VERSION = "{{ hbd_version }}";
 
     function hostNameHtml(data) {
+      var rawName = data.raw_name || data.name.replace(/<[^>]+>/g, '').replace('*', '').trim();
       var nameHtml = data.name;
       if (!data.hbc_version || data.hbc_version !== HBD_VERSION) {
         nameHtml += ' 🥀';
       }
-      return data.dyn ? '<b>' + nameHtml + '</b>' : nameHtml;
+      var display = data.dyn ? '<b>' + nameHtml + '</b>' : nameHtml;
+      return '<a class="host-link" href="/plugins#' + encodeURIComponent(rawName) + '">' + display + '</a>';
     }
 
     function setup() {
@@ -404,7 +408,7 @@
         );
         if (data.connections[i].state == "up") {
           state = '<span class="state-up">up</span>';
-          latency = Number.parseFloat(data.connections[i].rtts[0]).toFixed(2);
+          latency = String(Math.round(Number.parseFloat(data.connections[i].rtts[0])));
         } else {
           if (data.connections[i].state == "unknown") {
             state = "";
@@ -511,7 +515,7 @@
           <tbody id="ntablebody">
             {% for host in hosts %}
             <tr class="{% if host.alert_critical_unacked > 0 or host.alert_critical_acked > 0 %}row-critical{% elif host.alert_warning_unacked > 0 or host.alert_warning_acked > 0 %}row-warning{% endif %}">
-              <td data-name="{{ host.name }}">{{ host.name }}{% if not host.hbc_version or host.hbc_version != hbd_version %} 🥀{% endif %}</td>
+              <td data-name="{{ host.name }}"><a class="host-link" href="/plugins#{{ host.raw_name | urlencode }}">{{ host.name }}{% if not host.hbc_version or host.hbc_version != hbd_version %} 🥀{% endif %}</a></td>
               <td style="text-align: center; color: #ff9800; font-weight: bold;">
                 {%- set warning_unacked = host.alert_warning_unacked -%}
                 {%- set warning_acked = host.alert_warning_acked -%}

hbd/server/templates/nav.html

@@ -11,6 +11,9 @@
     {% endif %}
     <a href="/about"{% if active_page == "about" %} class="active"{% endif %}>About</a>
   </div>
+  <div class="nav-pie" title="Host alert status">
+    <canvas id="alert-pie" width="44" height="44"></canvas>
+  </div>
   <div class="nav-clock" title="Click for full-screen clock">
     <canvas id="swiss-clock" width="44" height="44"></canvas>
   </div>
@@ -42,4 +45,52 @@
       });
     }
   })();
+
+  function drawAlertPie(critical, warning, ok) {
+    var canvas = document.getElementById('alert-pie');
+    if (!canvas) return;
+    var ctx = canvas.getContext('2d');
+    var SIZE = canvas.width;
+    var R = SIZE / 2;
+    ctx.clearRect(0, 0, SIZE, SIZE);
+    var total = critical + warning + ok;
+    if (total === 0) {
+      ctx.beginPath();
+      ctx.arc(R, R, R - 1, 0, Math.PI * 2);
+      ctx.fillStyle = '#ccc';
+      ctx.fill();
+      return;
+    }
+    var slices = [
+      { value: critical, color: '#e53935' },
+      { value: warning,  color: '#ffb300' },
+      { value: ok,       color: '#43a047' }
+    ];
+    var start = -Math.PI / 2;
+    slices.forEach(function(s) {
+      if (s.value === 0) return;
+      var sweep = (s.value / total) * Math.PI * 2;
+      ctx.beginPath();
+      ctx.moveTo(R, R);
+      ctx.arc(R, R, R - 1, start, start + sweep);
+      ctx.closePath();
+      ctx.fillStyle = s.color;
+      ctx.fill();
+      start += sweep;
+    });
+  }
+
+  function updateAlertPie() {
+    fetch('/api/0/alert_summary').then(function(r) {
+      if (!r.ok) return;
+      return r.json();
+    }).then(function(d) {
+      if (d) drawAlertPie(d.critical || 0, d.warning || 0, d.ok || 0);
+    }).catch(function() {});
+  }
+
+  document.addEventListener('DOMContentLoaded', function() {
+    updateAlertPie();
+    setInterval(updateAlertPie, 30000);
+  });
 </script>

hbd/server/templates/plugins.html

@@ -131,6 +131,52 @@
       text-overflow: ellipsis;
     }
 
+    .host-action-btn {
+      font-size: 0.75em;
+      font-weight: bold;
+      padding: 3px 10px;
+      border-radius: 4px;
+      border: none;
+      cursor: pointer;
+      text-decoration: none;
+      white-space: nowrap;
+    }
+    .host-action-btn.update-btn {
+      background: #e3f2fd;
+      color: #1565c0;
+    }
+    .host-action-btn.update-btn:hover { background: #bbdefb; }
+    .host-action-btn.delete-btn {
+      background: #ffebee;
+      color: #c62828;
+    }
+    .host-action-btn.delete-btn:hover { background: #ffcdd2; }
+
+    /* ── Action result toast ───────────────────────────────────── */
+    #action-toast {
+      position: fixed;
+      bottom: 24px;
+      left: 50%;
+      transform: translateX(-50%) translateY(20px);
+      background: #323232;
+      color: #fff;
+      padding: 12px 22px;
+      border-radius: 6px;
+      font-size: 0.9em;
+      max-width: 480px;
+      text-align: center;
+      opacity: 0;
+      pointer-events: none;
+      transition: opacity 0.25s, transform 0.25s;
+      z-index: 9000;
+      white-space: pre-wrap;
+    }
+    #action-toast.show {
+      opacity: 1;
+      transform: translateX(-50%) translateY(0);
+    }
+    #action-toast.error { background: #c62828; }
+
     /* ── Host body ──────────────────────────────────────────────── */
 
     .host-body {
@@ -379,11 +425,17 @@
               <span class="nagios-badge" id="nagios-badge-{{ host.name }}">—</span>
               {% endif %}
               <span class="os-label" id="os-label-{{ host.name }}"></span>
+              {% if host.is_owner %}
+              <button class="host-action-btn update-btn"
+                      onclick="event.stopPropagation(); hostAction(this, '/u?h={{ host.name }}')">Update</button>
+              <button class="host-action-btn delete-btn"
+                      onclick="event.stopPropagation(); hostDelete(this, '{{ host.name }}')">Delete</button>
+              {% endif %}
             </div>
           </div>
 
           <div class="host-body">
-            {% set plugin_order = ['os_info','cpu_monitor','memory_monitor','disk_monitor','network_monitor','nagios_runner','filesystem_info'] %}
+            {% set plugin_order = ['os_info','cpu_monitor','memory_monitor','disk_monitor','network_monitor','zfs_monitor','nagios_runner','filesystem_info'] %}
             {% for plugin in plugin_order if plugin in host.plugins %}
             <div class="plugin-accordion collapsed"
                  data-hostname="{{ host.name }}"
@@ -447,6 +499,17 @@
         return pluginCache[hostname]?.[pluginName] ?? null;
       }
 
+      // Return worst nagios exit code (0-3) found in a nagios_runner data object.
+      function nagiosWorstStatus(data) {
+        let worst = 0;
+        for (const [k, v] of Object.entries(data || {})) {
+          if (k.endsWith('_status_code') && typeof v === 'number' && v > worst) {
+            worst = v;
+          }
+        }
+        return worst;
+      }
+
       // ── Fetch helpers ───────────────────────────────────────────────────────
 
       async function fetchPlugin(hostname, pluginName) {
@@ -548,13 +611,13 @@
           ? chips.join('')
           : '<span class="glance-loading">—</span>';
 
-        // Nagios badge
+        // Nagios badge — derive worst status from individual check codes
         const nagios = getCache(hostname, 'nagios_runner');
         if (nagosBadge && nagios) {
-          const status = (nagios.data.overall_status || '—').toUpperCase();
+          const worst = nagiosWorstStatus(nagios.data);
-          const cls = status === 'OK' ? 'ok'
+          const names = {0:'OK', 1:'WARNING', 2:'CRITICAL', 3:'UNKNOWN'};
-            : status === 'WARNING' ? 'warning'
+          const status = names[worst] || '—';
-            : status === 'CRITICAL' ? 'critical' : '';
+          const cls = worst === 0 ? 'ok' : worst === 1 ? 'warning' : worst >= 2 ? 'critical' : '';
           nagosBadge.className = `nagios-badge ${cls}`;
           nagosBadge.textContent = status;
         }
@@ -663,9 +726,10 @@
             break;
           }
           case 'nagios_runner': {
-            const status = (d.overall_status || '?').toUpperCase();
+            const worst = nagiosWorstStatus(d);
-            const count = d.plugin_count;
+            const names = {0:'OK', 1:'WARNING', 2:'CRITICAL', 3:'UNKNOWN'};
-            text = status + (count != null ? ` — ${count} checks` : '');
+            const codes = Object.keys(d).filter(k => k.endsWith('_status_code'));
+            text = (names[worst] || '?') + (codes.length ? ` — ${codes.length} checks` : '');
             break;
           }
           case 'filesystem_info': {
@@ -673,6 +737,19 @@
             text = `${count} filesystem${count !== 1 ? 's' : ''}`;
             break;
           }
+          case 'zfs_monitor': {
+            const pools = d.pools || {};
+            const names = Object.keys(pools);
+            if (names.length === 0) { text = 'No pools'; break; }
+            const degraded = names.filter(n => pools[n].health && pools[n].health !== 'ONLINE');
+            text = names.map(n => {
+              const p = pools[n];
+              const cap = p.capacity != null ? ` ${p.capacity.toFixed(0)}%` : '';
+              return `${n}${cap}`;
+            }).join(' · ');
+            if (degraded.length) text += ` ⚠ ${degraded.map(n => pools[n].health).join(',')}`;
+            break;
+          }
           default:
             text = 'Loaded';
         }
@@ -694,6 +771,7 @@
           case 'memory_monitor': html = renderMemoryTable(cached.data); break;
           case 'disk_monitor':   html = renderDiskTables(cached.data); break;
           case 'network_monitor':html = renderNetworkTables(cached.data); break;
+          case 'zfs_monitor':    html = renderZfsTables(cached.data); break;
           case 'nagios_runner':  html = renderNagiosTable(cached.data); break;
           case 'filesystem_info':html = renderFilesystemTable(cached.data); break;
           default:               html = renderGenericTable(cached.data); break;
@@ -1024,6 +1102,66 @@
         return html;
       }
 
+      function renderZfsTables(d) {
+        const pools = d.pools || {};
+        const names = Object.keys(pools);
+        if (names.length === 0) return '<div class="no-data">No ZFS pools found</div>';
+
+        const healthCls = h => {
+          if (!h || h === 'ONLINE') return 'pct-ok';
+          if (h === 'DEGRADED') return 'pct-warn';
+          return 'pct-crit';
+        };
+
+        let pt = '<table class="data-table"><thead><tr>'
+          + '<th>Pool</th><th>Health</th>'
+          + '<th class="num">Size</th><th class="num">Used</th>'
+          + '<th class="num">Free</th><th class="num">Cap %</th>'
+          + '<th class="num">Frag %</th><th class="num">Dedup</th>'
+          + '</tr></thead><tbody>';
+        for (const name of names) {
+          const p = pools[name];
+          const cap = p.capacity != null ? p.capacity : 0;
+          const capCls = cap > 90 ? 'pct-crit' : cap > 75 ? 'pct-warn' : 'pct-ok';
+          pt += `<tr>
+            <td class="iface-name">${escHtml(name)}</td>
+            <td class="${healthCls(p.health)}">${escHtml(p.health || '—')}</td>
+            <td class="num">${formatBytes(p.size || 0)}</td>
+            <td class="num">${formatBytes(p.alloc || 0)}</td>
+            <td class="num">${formatBytes(p.free || 0)}</td>
+            <td class="num ${capCls}">${cap.toFixed(1)}%</td>
+            <td class="num">${p.frag != null ? p.frag.toFixed(1) + '%' : '—'}</td>
+            <td class="num">${p.dedup != null ? p.dedup.toFixed(2) + 'x' : '—'}</td>
+          </tr>`;
+        }
+        pt += '</tbody></table>';
+
+        const hasIo = names.some(n => pools[n].read_ops != null);
+        if (!hasIo) return pt;
+
+        let iot = '<table class="data-table"><thead><tr>'
+          + '<th>Pool</th>'
+          + '<th class="num">Read ops</th><th class="num">Write ops</th>'
+          + '<th class="num">Read BW</th><th class="num">Write BW</th>'
+          + '</tr></thead><tbody>';
+        for (const name of names) {
+          const p = pools[name];
+          iot += `<tr>
+            <td class="iface-name">${escHtml(name)}</td>
+            <td class="num">${p.read_ops != null ? p.read_ops.toLocaleString() : '—'}</td>
+            <td class="num">${p.write_ops != null ? p.write_ops.toLocaleString() : '—'}</td>
+            <td class="num">${p.read_bw != null ? formatBytes(p.read_bw) : '—'}</td>
+            <td class="num">${p.write_bw != null ? formatBytes(p.write_bw) : '—'}</td>
+          </tr>`;
+        }
+        iot += '</tbody></table>';
+
+        return `<div class="flex-tables">
+          <div><div class="table-section-label">Pools</div>${pt}</div>
+          <div><div class="table-section-label">I/O (cumulative)</div>${iot}</div>
+        </div>`;
+      }
+
       function renderGenericTable(d) {
         let html = '<table class="data-table"><thead><tr><th>Field</th><th>Value</th></tr></thead><tbody>';
         for (const [k, v] of Object.entries(d)) {
@@ -1082,12 +1220,68 @@
       // ── Init ────────────────────────────────────────────────────────────────
 
       document.addEventListener('DOMContentLoaded', () => {
+        // If a host fragment is in the URL, expand and scroll to that host;
+        // otherwise expand the first host as before.
+        const hash = window.location.hash;
+        if (hash) {
+          const hostname = decodeURIComponent(hash.slice(1));
+          const card = document.querySelector(`.host-card[data-hostname="${hostname}"]`);
+          if (card) {
+            card.classList.remove('collapsed');
+            fetchHostGlance(hostname);
+            setTimeout(() => card.scrollIntoView({ behavior: 'smooth', block: 'start' }), 150);
+            return;
+          }
+        }
         const first = document.querySelector('.host-card');
         if (first) {
           first.classList.remove('collapsed');
           fetchHostGlance(first.dataset.hostname);
         }
       });
+      // ── Host action helpers ──────────────────────────────────────
+
+      let _toastTimer = null;
+      function showToast(msg, isError) {
+        const t = document.getElementById('action-toast');
+        t.textContent = msg;
+        t.classList.toggle('error', !!isError);
+        t.classList.add('show');
+        clearTimeout(_toastTimer);
+        _toastTimer = setTimeout(() => t.classList.remove('show'), 4000);
+      }
+
+      async function hostAction(btn, url) {
+        btn.disabled = true;
+        try {
+          const res = await fetch(url);
+          const text = await res.text();
+          showToast(text, !res.ok);
+        } catch (e) {
+          showToast('Request failed: ' + e.message, true);
+        } finally {
+          btn.disabled = false;
+        }
+      }
+
+      async function hostDelete(btn, hostname) {
+        if (!confirm('Delete host ' + hostname + '?')) return;
+        btn.disabled = true;
+        try {
+          const res = await fetch('/d?h=' + encodeURIComponent(hostname));
+          const text = await res.text();
+          showToast(text, !res.ok);
+          if (res.ok) {
+            const card = document.querySelector(`.host-card[data-hostname="${hostname}"]`);
+            if (card) card.remove();
+          }
+        } catch (e) {
+          showToast('Request failed: ' + e.message, true);
+          btn.disabled = false;
+        }
+      }
     </script>
+
+    <div id="action-toast"></div>
   </body>
 </html>

hbd/server/templates/settings.html

@@ -254,6 +254,17 @@
     .host-bool { text-align: center; }
     .dot-yes { color: #2e7d32; font-size: 1.1em; }
     .dot-no  { color: #ddd;    font-size: 1.1em; }
+
+    /* ---- Threshold configurations ---- */
+    .thresh-config { margin: 12px 20px 20px; }
+    .thresh-config-name {
+      font-weight: 600; font-size: 0.9em; color: #1a237e;
+      margin-bottom: 6px;
+    }
+    .mini-table .warn  { color: #e65100; font-weight: 600; }
+    .mini-table .crit  { color: #b71c1c; font-weight: 600; }
+    .mini-table .dim   { color: #aaa; }
+    .mini-table .metric-path { font-family: monospace; font-size: 0.88em; }
   </style>
 
   <body>
@@ -394,6 +405,49 @@
             {% endif %}
             {% endif %}
 
+            {# ---- Threshold configurations section ---- #}
+            {% if section.id == "thresholds" %}
+            {% if section.threshold_configs %}
+            {% for tc in section.threshold_configs %}
+            <div class="thresh-config">
+              <div class="thresh-config-name">{{ tc.name }}</div>
+              {% if tc.metrics %}
+              <div style="overflow-x: auto;">
+                <table class="mini-table">
+                  <thead>
+                    <tr>
+                      <th>Metric</th>
+                      <th>Op</th>
+                      <th>Warning</th>
+                      <th>Critical</th>
+                      <th>Hysteresis</th>
+                      <th>Count</th>
+                    </tr>
+                  </thead>
+                  <tbody>
+                    {% for m in tc.metrics %}
+                    <tr {% if not m.enabled %} style="opacity:0.45"{% endif %}>
+                      <td class="metric-path">{{ m.metric }}</td>
+                      <td>{{ m.operator or '>' }}</td>
+                      <td class="warn">{{ m.warning if m.warning is not none else '—' }}</td>
+                      <td class="crit">{{ m.critical if m.critical is not none else '—' }}</td>
+                      <td class="dim">{{ '%.0f%%' % (m.hysteresis * 100) if m.hysteresis else '—' }}</td>
+                      <td class="dim">{{ m.count }}</td>
+                    </tr>
+                    {% endfor %}
+                  </tbody>
+                </table>
+              </div>
+              {% else %}
+              <span class="val-empty">No thresholds defined.</span>
+              {% endif %}
+            </div>
+            {% endfor %}
+            {% else %}
+            <div class="field-row"><span class="val-empty">No threshold configurations defined.</span></div>
+            {% endif %}
+            {% endif %}
+
             {# ---- Hosts section ---- #}
             {% if section.id == "hosts" %}
             {% if section.hosts %}

hbd/server/threshold.py

@@ -9,10 +9,11 @@ This module provides a flexible threshold checking system that:
 - Supports multiple comparison operators
 """
 
+import asyncio
 import logging
 import time
 from enum import Enum
-from typing import Dict, Any, Optional, Tuple, Callable
+from typing import Dict, List, Any, Optional, Tuple, Callable
 from . import notify as notify_mod
 from .config import THRESHOLD_DEFAULTS
 
@@ -35,6 +36,7 @@ class ComparisonOperator(Enum):
     LTE = "<="      # Less than or equal
     EQ = "=="       # Equal to
     NEQ = "!="      # Not equal to
+    NAGIOS = "nagios"  # Nagios exit-code semantics: 0=OK 1=WARNING 2=CRITICAL 3=UNKNOWN
 
 
 class AlertState:
@@ -56,6 +58,7 @@ class AlertState:
         self.last_notification = None
         self.threshold_value = None  # The threshold value that triggered alert
         self.operator = None  # The comparison operator (>, <, >=, etc.)
+        self.hysteresis: Optional[float] = None  # Hysteresis fraction used for recovery
         self.formatted_message = None  # Formatted display message for UI
         self.acknowledged = False  # Whether alert has been acknowledged
         self.acknowledged_at = None  # Timestamp when acknowledged
@@ -151,6 +154,15 @@ class AlertState:
         if self.formatted_message is not None:
             result["formatted_message"] = self.formatted_message
 
+        # Compute and expose the recovery threshold so the UI can display it
+        if (self.hysteresis and self.threshold_value is not None
+                and self.operator is not None):
+            ha = abs(self.threshold_value * self.hysteresis)
+            if self.operator in ('>', '>='):
+                result["recovery_threshold"] = round(self.threshold_value - ha, 4)
+            elif self.operator in ('<', '<='):
+                result["recovery_threshold"] = round(self.threshold_value + ha, 4)
+
         return result
     
     def __setstate__(self, state):
@@ -158,6 +170,8 @@ class AlertState:
         self.__dict__.update(state)
         if not hasattr(self, 'consecutive_count'):
             self.consecutive_count = 0
+        if not hasattr(self, 'hysteresis'):
+            self.hysteresis = None
 
     def acknowledge(self):
         """Acknowledge this alert to stop reminder notifications."""
@@ -226,6 +240,16 @@ class ThresholdConfig:
         if not self.enabled:
             return AlertLevel.OK
 
+        # Nagios exit-code semantics: value IS the severity
+        if self.operator == ComparisonOperator.NAGIOS:
+            try:
+                code = int(value)
+            except (TypeError, ValueError):
+                return AlertLevel.UNKNOWN
+            return {0: AlertLevel.OK, 1: AlertLevel.WARNING, 2: AlertLevel.CRITICAL}.get(
+                code, AlertLevel.UNKNOWN
+            )
+
         try:
             # Convert value to float for comparison
             value = float(value)
@@ -262,6 +286,10 @@ class ThresholdConfig:
         """
         new_level = self.evaluate(value)
 
+        # Nagios exit codes are discrete integers — hysteresis doesn't apply
+        if self.operator == ComparisonOperator.NAGIOS:
+            return new_level
+
         # If no hysteresis, return new level
         if self.hysteresis == 0.0:
             return new_level
@@ -328,14 +356,17 @@ class ThresholdChecker:
             renotify_interval: Seconds between repeat notifications (default: 1 hour)
             journal: Optional MessageJournal instance for logging threshold events
         """
-        # Named threshold configurations: {config_name: {metric_path: ThresholdConfig}}
+        # Named threshold configurations (pre-merged: defaults + overrides): {config_name: {metric_path: ThresholdConfig}}
         self.threshold_configs = {}
 
+        # Raw overrides only for each named config (no defaults baked in): {config_name: {metric_path: ThresholdConfig}}
+        self.threshold_raw_configs: Dict[str, Dict[str, ThresholdConfig]] = {}
+
         # Single threshold set for backward compatibility: {metric_path: ThresholdConfig}
         self.thresholds = {}
 
-        # Host to config name mapping: {host_name: config_name}
+        # Host to ordered list of config names: {host_name: [config_name, ...]}
-        self.host_config_mapping = {}
+        self.host_config_mapping: Dict[str, List[str]] = {}
 
         # Default config name to use when no mapping exists
         self.default_config = "default"
@@ -372,6 +403,7 @@ class ThresholdChecker:
         
         # Clear old configuration
         self.threshold_configs.clear()
+        self.threshold_raw_configs.clear()
         self.thresholds.clear()
         self.host_config_mapping.clear()
         self.grace_seconds = float(config.get("grace", 2))
@@ -391,10 +423,24 @@ class ThresholdChecker:
         Supports two formats:
         1. Legacy format with direct 'thresholds' section
         2. New format with 'threshold_configs' and 'host_threshold_mapping'
+
+        In all cases, THRESHOLD_DEFAULTS are seeded into threshold_configs["default"]
+        so the Settings page always shows the built-in defaults.
+        _parse_multi_config() overwrites this with the fully-merged effective defaults.
         """
+        # Always expose built-in defaults through threshold_configs["default"] so
+        # the Settings page has something to display even in legacy/no-config mode.
+        seed: Dict[str, ThresholdConfig] = {}
+        for plugin_name, plugin_thresholds in THRESHOLD_DEFAULTS.get("thresholds", {}).items():
+            if isinstance(plugin_thresholds, dict):
+                self._parse_plugin_thresholds(plugin_name, plugin_thresholds, target_dict=seed)
+        if seed:
+            self.threshold_configs["default"] = seed
+            self.threshold_raw_configs["default"] = {}
+
         # Check for new multi-config format
         if "threshold_configs" in config:
-            self._parse_multi_config(config)
+            self._parse_multi_config(config)  # overwrites threshold_configs["default"]
         elif "thresholds" in config:
             # Legacy single threshold configuration
             self._parse_legacy_config(config)
@@ -424,9 +470,10 @@ class ThresholdChecker:
                         self._parse_plugin_thresholds(plugin_name, plugin_thresholds, target_dict=effective_defaults)
 
         self.threshold_configs["default"] = dict(effective_defaults)
+        self.threshold_raw_configs["default"] = {}
         logger.info("Registered 'default' threshold config with %d metrics", len(effective_defaults))
 
-        # Parse each named configuration, seeding it with effective_defaults first
+        # Parse each named configuration
         for config_name, config_data in threshold_configs.items():
             if config_name == "default":
                 continue  # already handled above
@@ -440,33 +487,41 @@ class ThresholdChecker:
                 continue
 
             logger.info("Parsing threshold configuration: %s", config_name)
-            self.threshold_configs[config_name] = dict(effective_defaults)
 
+            # Raw overrides only (used for multi-config layering)
+            raw_overrides: Dict[str, ThresholdConfig] = {}
             thresholds_config = config_data["thresholds"]
             for plugin_name, plugin_thresholds in thresholds_config.items():
-                if not isinstance(plugin_thresholds, dict):
+                if isinstance(plugin_thresholds, dict):
-                    continue
+                    self._parse_plugin_thresholds(plugin_name, plugin_thresholds, target_dict=raw_overrides)
+            self.threshold_raw_configs[config_name] = raw_overrides
 
-                self._parse_plugin_thresholds(
+            # Pre-merged version (defaults + overrides) for single-config fast path
-                    plugin_name,
+            self.threshold_configs[config_name] = dict(effective_defaults)
-                    plugin_thresholds,
+            self.threshold_configs[config_name].update(raw_overrides)
-                    target_dict=self.threshold_configs[config_name]
-                )
 
-        # Parse host to config mapping from two possible sources
+        # Parse host → config list mapping from two possible sources
-        # 1. New format: hosts section with threshold_config attribute
+
+        def _normalise(value) -> List[str]:
+            """Accept a string or list; always return a list."""
+            if isinstance(value, list):
+                return [str(v) for v in value]
+            return [str(value)]
+
+        # 1. hosts section with threshold_config attribute (string or list)
         if "hosts" in config:
             hosts_config = config["hosts"]
             if isinstance(hosts_config, dict):
                 for host_name, host_attrs in hosts_config.items():
                     if isinstance(host_attrs, dict) and "threshold_config" in host_attrs:
-                        self.host_config_mapping[host_name] = host_attrs["threshold_config"]
+                        self.host_config_mapping[host_name] = _normalise(host_attrs["threshold_config"])
 
-        # 2. Legacy format: host_threshold_mapping section (for backward compatibility)
+        # 2. Legacy host_threshold_mapping section (string values only)
         if "host_threshold_mapping" in config:
             legacy_mapping = config.get("host_threshold_mapping", {})
             if isinstance(legacy_mapping, dict):
-                self.host_config_mapping.update(legacy_mapping)
+                for host_name, value in legacy_mapping.items():
+                    self.host_config_mapping[host_name] = _normalise(value)
         
         # Set default config (first one alphabetically or explicitly set)
         self.default_config = config.get("default_threshold_config", "default")
@@ -531,11 +586,14 @@ class ThresholdChecker:
             warning = threshold_config.get("warning")
             critical = threshold_config.get("critical")
             operator = threshold_config.get("operator", ">")
-            display = threshold_config.get("display", "(threshold: {op_symbol} {threshold_value})")
+            # Nagios operator maps exit codes directly; no numeric thresholds needed
-            hysteresis = threshold_config.get("hysteresis", 0.1)  # 10% default
+            is_nagios_op = (operator == "nagios")
+            default_display = "{check_name}: {output}" if is_nagios_op else "(threshold: {op_symbol} {threshold_value})"
+            display = threshold_config.get("display", default_display)
+            hysteresis = threshold_config.get("hysteresis", 0.0 if is_nagios_op else 0.02)
             enabled = threshold_config.get("enabled", True)
 
-            if warning is None and critical is None:
+            if warning is None and critical is None and not is_nagios_op:
                 logger.warning("No thresholds defined for %s, skipping", metric_path)
                 continue
             
@@ -635,7 +693,7 @@ class ThresholdChecker:
         warning = rtt_thresholds.get("warning")
         critical = rtt_thresholds.get("critical")
         operator = rtt_thresholds.get("operator", ">")
-        hysteresis = rtt_thresholds.get("hysteresis", 0.1)  # 10% default
+        hysteresis = rtt_thresholds.get("hysteresis", 0.02)  # 2% default
         enabled = rtt_thresholds.get("enabled", True)
         display = rtt_thresholds.get("display")
         count = rtt_thresholds.get("count", 1)
@@ -664,7 +722,10 @@ class ThresholdChecker:
         )
     
     def get_thresholds_for_host(self, host_name: str) -> Dict[str, ThresholdConfig]:
-        """Get the appropriate threshold configuration for a host.
+        """Get the effective threshold configuration for a host.
+
+        When threshold_config is a list, configs are applied left-to-right on top
+        of the default thresholds so earlier entries can be overridden by later ones.
 
         Args:
             host_name: Name of the host
@@ -676,23 +737,40 @@ class ThresholdChecker:
         if self.thresholds and not self.threshold_configs:
             return self.thresholds
 
-        # Multi-config mode: look up host-specific configuration
+        if not self.threshold_configs:
-        if self.threshold_configs:
+            return {}
-            config_name = self.host_config_mapping.get(host_name, self.default_config)
 
-            if config_name in self.threshold_configs:
+        config_names = self.host_config_mapping.get(host_name)
-                return self.threshold_configs[config_name]
+
-            else:
+        # No host-specific mapping → return pre-merged default
+        if not config_names:
+            return self.threshold_configs.get(self.default_config, {})
+
+        # Single config → fast path using pre-merged copy
+        if len(config_names) == 1:
+            name = config_names[0]
+            if name in self.threshold_configs:
+                return self.threshold_configs[name]
             logger.warning(
                 "Threshold config '%s' not found for host '%s', using default '%s'",
-                    config_name,
+                name, host_name, self.default_config,
-                    host_name,
-                    self.default_config
             )
             return self.threshold_configs.get(self.default_config, {})
 
-        # No thresholds configured
+        # Multiple configs → start from defaults, layer raw overrides in order
-        return {}
+        result = dict(self.threshold_configs.get(self.default_config, {}))
+        for name in config_names:
+            if name == self.default_config:
+                continue  # defaults already the base
+            raw = self.threshold_raw_configs.get(name)
+            if raw is None:
+                logger.warning(
+                    "Threshold config '%s' not found for host '%s', skipping",
+                    name, host_name,
+                )
+            else:
+                result.update(raw)
+        return result
     
     def check_value(
         self,
@@ -760,6 +838,12 @@ class ThresholdChecker:
         elif new_level == AlertLevel.WARNING and threshold.warning is not None:
             threshold_value = threshold.warning
 
+        # Keep hysteresis on the state so the UI can show the recovery threshold
+        if new_level != AlertLevel.OK:
+            alert_state.hysteresis = threshold.hysteresis
+        else:
+            alert_state.hysteresis = None
+
         # Update state and check for changes
         old_level = alert_state.level
         if alert_state.update(new_level, value, threshold_value, threshold.operator.value):
@@ -769,6 +853,36 @@ class ThresholdChecker:
             self._check_pending_or_renotify(host_name, alert_state, metric_path, value, threshold, None)
 
         return None
+    def _find_threshold(
+        self, thresholds: Dict[str, "ThresholdConfig"], metric_path: str
+    ) -> Tuple[Optional["ThresholdConfig"], Optional[str]]:
+        """Return (threshold, check_name) for *metric_path*, falling back to suffix matches.
+
+        Allows generic thresholds like ``nagios_runner.status_code`` to match
+        fully-qualified paths like ``nagios_runner.check_disk_root_status_code``.
+        The exact match is always tried first; then successive leading
+        underscore-delimited segments are stripped from the field name until
+        a match is found or no segments remain.
+
+        Returns:
+            (ThresholdConfig, None) for an exact match.
+            (ThresholdConfig, "check_disk_root") for a suffix match — the second
+            element is the stripped prefix, available as ``{check_name}`` in
+            display format templates.
+            (None, None) when no threshold is found.
+        """
+        if metric_path in thresholds:
+            return thresholds[metric_path], None
+        plugin, sep, field = metric_path.partition(".")
+        if not sep:
+            return None, None
+        parts = field.split("_")
+        for i in range(1, len(parts)):
+            candidate = plugin + "." + "_".join(parts[i:])
+            if candidate in thresholds:
+                return thresholds[candidate], "_".join(parts[:i])
+        return None, None
+
     def check_plugin_data(
         self,
         host_name: str,
@@ -797,11 +911,10 @@ class ThresholdChecker:
         for metric_name, value in data.items():
             metric_path = f"{plugin_name}.{metric_name}"
 
-            if metric_path not in thresholds:
+            threshold, check_name = self._find_threshold(thresholds, metric_path)
+            if threshold is None:
                 continue
 
-            threshold = thresholds[metric_path]
-            
             # Get or create alert state
             if metric_path not in alert_states:
                 alert_states[metric_path] = AlertState(metric_path)
@@ -821,13 +934,15 @@ class ThresholdChecker:
             elif new_level == AlertLevel.WARNING and threshold.warning is not None:
                 threshold_value = threshold.warning
 
+            alert_state.hysteresis = threshold.hysteresis if new_level != AlertLevel.OK else None
+
             # Update state and check for changes
             old_level = alert_state.level
             if alert_state.update(new_level, value, threshold_value, threshold.operator.value):
                 state_changes.append((metric_path, old_level, new_level, value))
-                self._apply_grace(host_name, alert_state, metric_path, old_level, new_level, value, threshold, data)
+                self._apply_grace(host_name, alert_state, metric_path, old_level, new_level, value, threshold, data, check_name=check_name, metric_name=metric_name)
             elif new_level != AlertLevel.OK:
-                self._check_pending_or_renotify(host_name, alert_state, metric_path, value, threshold, data)
+                self._check_pending_or_renotify(host_name, alert_state, metric_path, value, threshold, data, check_name=check_name, metric_name=metric_name)
 
         # Check nested metrics (e.g., partition data in disk_monitor)
         self._check_nested_metrics(
@@ -887,6 +1002,8 @@ class ThresholdChecker:
                     elif new_level == AlertLevel.WARNING and threshold.warning is not None:
                         threshold_value = threshold.warning
 
+                    alert_state.hysteresis = threshold.hysteresis if new_level != AlertLevel.OK else None
+
                     old_level = alert_state.level
                     if alert_state.update(new_level, value, threshold_value, threshold.operator.value):
                         state_changes.append((metric_path, old_level, new_level, value))
@@ -903,6 +1020,8 @@ class ThresholdChecker:
         value: Any,
         threshold: ThresholdConfig,
         plugin_data: Optional[Dict[str, Any]] = None,
+        check_name: Optional[str] = None,
+        metric_name: Optional[str] = None,
     ):
         """Trigger a notification for an alert state change.
         
@@ -929,50 +1048,45 @@ class ThresholdChecker:
         import math
         display_value = "overdue" if isinstance(value, float) and math.isinf(value) else value
 
-        # Format message
+        # Format message — for the nagios operator there is no numeric threshold_value;
+        # render the display template whenever one is available.
+        has_display = threshold_value is not None or threshold.operator == ComparisonOperator.NAGIOS
+
+        def _fmt():
+            return self._format_display(
+                threshold.display,
+                value=display_value,
+                threshold_value=threshold_value,
+                op_symbol=op_symbol,
+                plugin_data=plugin_data,
+                check_name=check_name,
+                metric_name=metric_name,
+            )
+
         if new_level == AlertLevel.OK:
             lvl = "RECOVER"
             message = f"{metric_path} = {display_value} ({old_level.name} -> OK)"
         elif new_level == AlertLevel.WARNING:
             lvl = "WARNING"
-            if threshold_value is not None:
+            if has_display:
-                threshold_info = self._format_display(
+                message = f"{metric_path} = {display_value} {_fmt()}"
-                    threshold.display,
-                    value=display_value,
-                    threshold_value=threshold_value,
-                    op_symbol=op_symbol,
-                    plugin_data=plugin_data
-                )
-                message = f"{metric_path} = {display_value} {threshold_info}"
             else:
                 message = f"{metric_path} = {display_value}"
         elif new_level == AlertLevel.CRITICAL:
             lvl = "CRITICAL"
-            if threshold_value is not None:
+            if has_display:
-                threshold_info = self._format_display(
+                message = f"{metric_path} = {display_value} {_fmt()}"
-                    threshold.display,
-                    value=display_value,
-                    threshold_value=threshold_value,
-                    op_symbol=op_symbol,
-                    plugin_data=plugin_data
-                )
-                message = f"{metric_path} = {display_value} {threshold_info}"
             else:
                 message = f"{metric_path} = {display_value}"
         else:
             lvl = "UNKNOWN"
+            if has_display:
+                message = f"{metric_path} = {display_value} {_fmt()}"
+            else:
                 message = f"{metric_path} = {display_value}"
 
-        # Return the formatted threshold info for storing in AlertState
+        # Formatted threshold info stored on AlertState for the UI
-        formatted_threshold_msg = None
+        formatted_threshold_msg = _fmt() if has_display and new_level != AlertLevel.OK else None
-        if threshold_value is not None and new_level != AlertLevel.OK:
-            formatted_threshold_msg = self._format_display(
-                threshold.display,
-                value=display_value,
-                threshold_value=threshold_value,
-                op_symbol=op_symbol,
-                plugin_data=plugin_data
-            )
 
         return lvl, message, formatted_threshold_msg
     
@@ -987,6 +1101,11 @@ class ThresholdChecker:
         value: Any,
     ):
         """Send notification and log to journal/eventlog."""
+        from . import hbdclass
+        host = hbdclass.Host.hosts.get(host_name)
+        if host is not None and not host.watched:
+            eventlog(host_name, lvl, message, service="threshold")
+            return
         asyncio.get_event_loop().create_task(notify_mod.send_notification(
             host_name,
             notify_mod.Notification(
@@ -999,7 +1118,6 @@ class ThresholdChecker:
         # Log to journal
         if self.journal is not None:
             try:
-                import asyncio
                 loop = asyncio.get_event_loop()
                 loop.create_task(self.journal.log_threshold_event(
                     host_name=host_name,
@@ -1017,18 +1135,24 @@ class ThresholdChecker:
         self,
         display_format: str,
         value: Any,
-        threshold_value: float,
+        threshold_value: Optional[float],
         op_symbol: str,
         plugin_data: Optional[Dict[str, Any]] = None,
+        check_name: Optional[str] = None,
+        metric_name: Optional[str] = None,
     ) -> str:
         """Format the display string using available data.
 
-        Args:
+        Available template variables:
-            display_format: Format string from threshold config
+            {value}           - current metric value
-            value: Current metric value
+            {threshold_value} - threshold that was exceeded
-            threshold_value: Threshold value that was exceeded
+            {op_symbol}       - comparison operator (>, <, >=, <=, ==, !=)
-            op_symbol: Comparison operator symbol
+            {check_name}      - prefix stripped for generic threshold match
-            plugin_data: Optional dictionary of plugin data fields
+                                (e.g. "check_disk_root" when metric
+                                "check_disk_root_status_code" matched generic
+                                threshold "status_code")
+            {metric_name}     - field name within the plugin data dict
+            Any key from plugin_data is also available.
 
         Returns:
             Formatted display string
@@ -1036,14 +1160,34 @@ class ThresholdChecker:
         # Build format context with standard variables
         format_context = {
             'value': value,
-            'threshold_value': threshold_value,
             'op_symbol': op_symbol,
         }
+        if threshold_value is not None:
+            format_context['threshold_value'] = threshold_value
+
+        # Add generic-match context variables when available
+        if check_name is not None:
+            format_context['check_name'] = check_name
+        if metric_name is not None:
+            format_context['metric_name'] = metric_name
 
         # Add all plugin data fields if available
         if plugin_data:
             format_context.update(plugin_data)
 
+        # For nagios_runner generic matches, expose the matched check's output
+        # and status as short aliases {output} and {status} so display templates
+        # don't need to use the full {check_disk_root_output} form.
+        if check_name and plugin_data:
+            if 'output' not in format_context:
+                output = plugin_data.get(f"{check_name}_output")
+                if output is not None:
+                    format_context['output'] = output
+            if 'status' not in format_context:
+                status = plugin_data.get(f"{check_name}_status")
+                if status is not None:
+                    format_context['status'] = status
+        
         try:
             # Format the display string
             return display_format.format(**format_context)
@@ -1073,17 +1217,22 @@ class ThresholdChecker:
         value: Any,
         threshold: ThresholdConfig,
         plugin_data: Optional[Dict[str, Any]],
+        check_name: Optional[str] = None,
+        metric_name: Optional[str] = None,
     ) -> None:
         """Handle a state-change transition with grace-period logic.
 
-        Transitioning INTO alert: defers the notification for grace_seconds.
+        Transitioning INTO alert (worsening): defers the notification for grace_seconds.
+        De-escalation within alert states (e.g. CRITICAL→WARNING): no new notification;
+          the metric is still alerting so no RECOVER was sent.
         Transitioning TO OK:
           - Still in grace window (pending_since set): suppresses both the alert
             and the recovery — the spike never warranted a page.
           - Past grace: fires the RECOVER notification normally.
         """
         lvl, message, formatted_msg = self._trigger_notification(
-            host_name, metric_path, old_level, new_level, value, threshold, plugin_data
+            host_name, metric_path, old_level, new_level, value, threshold, plugin_data,
+            check_name=check_name, metric_name=metric_name,
         )
         alert_state.formatted_message = formatted_msg
 
@@ -1096,12 +1245,20 @@ class ThresholdChecker:
                 alert_state.pending_since = None
             else:
                 self._send_notification(host_name, lvl, message, metric_path, old_level, new_level, value)
-        else:
+        elif new_level.value > old_level.value:
+            # Worsening (OK→WARNING, OK→CRITICAL, WARNING→CRITICAL): schedule notification.
             alert_state.pending_since = time.time()
             logger.debug(
                 "Alert deferred (%.0fs grace): %s on %s = %s",
                 self.grace_seconds, metric_path, host_name, value,
             )
+        else:
+            # De-escalation within alert states (e.g. CRITICAL→WARNING): metric is still
+            # alerting but did not recover, so no new notification.
+            logger.debug(
+                "De-escalation %s→%s for %s on %s, no notification",
+                old_level.name, new_level.name, metric_path, host_name,
+            )
 
     def _check_pending_or_renotify(
         self,
@@ -1111,6 +1268,8 @@ class ThresholdChecker:
         value: Any,
         threshold: ThresholdConfig,
         plugin_data: Optional[Dict[str, Any]],
+        check_name: Optional[str] = None,
+        metric_name: Optional[str] = None,
     ) -> None:
         """Called when alert level is unchanged and non-OK.
 
@@ -1120,7 +1279,8 @@ class ThresholdChecker:
         if alert_state.pending_since is not None:
             if time.time() - alert_state.pending_since >= self.grace_seconds:
                 lvl, message, formatted_msg = self._trigger_notification(
-                    host_name, metric_path, AlertLevel.OK, alert_state.level, value, threshold, plugin_data
+                    host_name, metric_path, AlertLevel.OK, alert_state.level, value, threshold, plugin_data,
+                    check_name=check_name, metric_name=metric_name,
                 )
                 alert_state.formatted_message = formatted_msg
                 self._send_notification(
@@ -1129,7 +1289,7 @@ class ThresholdChecker:
                 alert_state.pending_since = None
             # else: still within grace window, do nothing
         else:
-            self._check_renotify(host_name, alert_state, metric_path, value, threshold, plugin_data)
+            self._check_renotify(host_name, alert_state, metric_path, value, threshold, plugin_data, check_name=check_name, metric_name=metric_name)
 
     def _check_renotify(
         self,
@@ -1139,6 +1299,8 @@ class ThresholdChecker:
         value: Any,
         threshold: ThresholdConfig,
         plugin_data: Optional[Dict[str, Any]] = None,
+        check_name: Optional[str] = None,
+        metric_name: Optional[str] = None,
     ):
         """Check if we should send a repeat notification.
         
@@ -1185,12 +1347,17 @@ class ThresholdChecker:
                     value=value,
                     threshold_value=threshold_value,
                     op_symbol=op_symbol,
-                    plugin_data=plugin_data
+                    plugin_data=plugin_data,
+                    check_name=check_name,
+                    metric_name=metric_name,
                 )
                 message = f"REMINDER ({alert_state.level.name}): {host_name} - {metric_path} = {value} {threshold_info}, ongoing for {int(now - alert_state.since)}s"
             else:
                 message = f"REMINDER ({alert_state.level.name}): {host_name} - {metric_path} = {value} (ongoing for {int(now - alert_state.since)}s)"
             
+            from . import hbdclass
+            host = hbdclass.Host.hosts.get(host_name)
+            if host is None or host.watched:
                 asyncio.get_event_loop().create_task(notify_mod.send_notification(
                     host_name,
                     notify_mod.Notification(
@@ -1199,9 +1366,29 @@ class ThresholdChecker:
                         level=alert_state.level.name,
                     ),
                 ))
+                logger.info("Re-notification sent: %s", message)
             alert_state.last_notification = now
             alert_state.notification_count += 1
-            logger.info("Re-notification sent: %s", message)
+    
+    def purge_stale_alerts(self, hbdclass) -> None:
+        """Remove alert states that have no matching threshold configuration.
+
+        Called after startup (pickle restore) and after each config reload so
+        that alerts orphaned by configuration changes do not linger forever.
+        Alerts whose metric_path is not present in the current threshold config
+        for that host are silently dropped.
+        """
+        for hostname, host in hbdclass.Host.hosts.items():
+            if not host.alert_states:
+                continue
+            configured = self.get_thresholds_for_host(hostname)
+            stale = [mp for mp in host.alert_states if self._find_threshold(configured, mp)[0] is None]
+            for mp in stale:
+                logger.info(
+                    "Purging stale alert state for %s / %s (no threshold configured)",
+                    hostname, mp,
+                )
+                del host.alert_states[mp]
 
     def get_active_alerts(self, alert_states: Dict[str, AlertState]) -> list:
         """

hbd/server/udp.py

@@ -211,6 +211,7 @@ def _make_timer_callbacks(uname, host, ctx):
         connection.newstate(connection.__class__.OVERDUE, now, cfg.get("grace", 2))
         msg = f"{connection.afam} overdue"
         eventlog(uname, "CRITICAL", msg)
+        if host.watched:
             asyncio.create_task(notify_mod.send_notification(
                 uname,
                 notify_mod.Notification(title=f"[CRITICAL] {uname}", body=msg, level="CRITICAL"),
@@ -407,6 +408,7 @@ def handle_datagram(msg: dict, addr, transport, ctx: dict):
 
     if res:
         eventlog(uname, "WARNING", res)
+        if host.watched:
             asyncio.create_task(notify_mod.send_notification(
                 uname,
                 notify_mod.Notification(title=f"[WARNING] {uname}", body=res, level="WARNING"),
@@ -420,6 +422,7 @@ def handle_datagram(msg: dict, addr, transport, ctx: dict):
 
     if boot:
         eventlog(uname, "INFO", "booted")
+        if host.watched:
             asyncio.create_task(notify_mod.send_notification(
                 uname,
                 notify_mod.Notification(title=f"[INFO] {uname}", body=f"{host.name} booted", level="INFO"),
@@ -437,9 +440,14 @@ def handle_datagram(msg: dict, addr, transport, ctx: dict):
         if not newh:
             if d == 0 or lasts == "unknown":
                 m = "%s is up" % (conn.afam)
+            elif d < 4:
+                # Transient blip (likely client restart) — skip log and notification
+                m = None
             else:
                 m = "%s back after being %s for %s" % (conn.afam, lasts, dur(d))
+            if m:
                 eventlog(uname, "RECOVER", m)
+                if host.watched:
                     asyncio.create_task(notify_mod.send_notification(
                         uname,
                         notify_mod.Notification(title=f"[RECOVER] {uname}", body=m, level="RECOVER"),
@@ -453,6 +461,7 @@ def handle_datagram(msg: dict, addr, transport, ctx: dict):
     if shutdown:
         m = "%s shutdown" % conn.afam
         eventlog(uname, "INFO", m)
+        if host.watched:
             asyncio.create_task(notify_mod.send_notification(
                 uname,
                 notify_mod.Notification(title=f"[INFO] {uname}", body=m, level="INFO"),

hbd/server/ws.py

@@ -13,7 +13,8 @@ from . import data
 
 logger = logging.getLogger(__name__)
 
-_connections: set = set()
+# Map of WebSocket → User object (or None when auth is disabled)
+_connections: dict = {}
 _loop: Optional[asyncio.AbstractEventLoop] = None
 _get_hosts: Optional[Callable[[], Iterable]] = None
 _verbose: bool = False
@@ -34,22 +35,52 @@ def setup(
     _verbose = verbose
 
 
+def _user_can_see_host(user, host_name: str) -> bool:
+    """Return True if *user* may see updates for *host_name* (manager or higher)."""
+    from . import hbdclass, users as users_mod
+    if user is None or not users_mod.users_enabled():
+        return True
+    if user.admin:
+        return True
+    host = hbdclass.Host.hosts.get(host_name)
+    if host is None:
+        return False
+    return host.is_manager(user.username)
+
+
+def _get_token(request) -> str:
+    """Extract session token from request (mirrors logic in http.py)."""
+    auth = request.headers.get("Authorization", "")
+    if auth.startswith("Bearer "):
+        return auth[7:].strip()
+    token = request.headers.get("X-Auth-Token", "")
+    if token:
+        return token
+    return request.cookies.get("hbd_session", "")
+
+
 async def handler(request):
     """aiohttp WebSocket upgrade handler — register as GET /ws."""
     from aiohttp import web
+    from . import users as users_mod
 
     ws = web.WebSocketResponse()
     await ws.prepare(request)
 
-    _connections.add(ws)
+    token = _get_token(request)
+    user = users_mod.get_session_user(token) if token else None
+
+    _connections[ws] = user
     remote = request.remote
     logger.info("WebSocket connected from %s", remote)
 
     try:
-        # Send current host state to the new client
+        # Send current host state, filtered to hosts this user may see
         if _get_hosts:
             try:
                 for h in list(_get_hosts()):
+                    host_name = h.get("raw_name") or h.get("name", "")
+                    if _user_can_see_host(user, host_name):
                         await ws.send_str(json.dumps({"type": "host", "data": h}))
             except Exception as e:
                 logger.error("Error sending initial hosts: %s", e)
@@ -74,7 +105,7 @@ async def handler(request):
     except Exception as e:
         logger.exception("WebSocket handler error from %s: %s", remote, e)
     finally:
-        _connections.discard(ws)
+        _connections.pop(ws, None)
         logger.info("WebSocket disconnected from %s", remote)
 
     return ws
@@ -83,25 +114,37 @@ async def handler(request):
 def broadcast(typ: str, payload) -> bool:
     """Thread-safe broadcast to all connected WebSocket clients.
 
+    For host and plugin updates, only sends to clients whose user has
+    manager-or-higher access to that host.  Other message types are
+    broadcast to all clients.
+
     Can be called from any thread; schedules sends on the event loop.
     Returns False if the loop is not running yet.
     """
     if not _loop:
         return False
+
+    # Determine the host name for access-filtered message types
+    host_name: Optional[str] = None
+    if typ in ("host", "plugin"):
+        host_name = payload.get("raw_name") or payload.get("host") or payload.get("name")
+
     jmsg = json.dumps({"type": typ, "data": payload})
 
     async def _send_all():
         dead = set()
-        for ws in list(_connections):
+        for ws, user in list(_connections.items()):
             try:
-                if not ws.closed:
+                if ws.closed:
-                    await ws.send_str(jmsg)
-                else:
                     dead.add(ws)
+                    continue
+                if host_name is not None and not _user_can_see_host(user, host_name):
+                    continue
+                await ws.send_str(jmsg)
             except Exception:
                 dead.add(ws)
         for ws in dead:
-            _connections.discard(ws)
+            _connections.pop(ws, None)
 
     asyncio.run_coroutine_threadsafe(_send_all(), _loop)
     return True

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "hbd"
-version = "5.1.12"
+version = "5.2.0"
 description = "Heartbeat monitoring system — client (hbc) and server (hbd)"
 readme = "README.md"
 requires-python = ">=3.11"

scripts/hbc_mini.py

@@ -41,7 +41,7 @@ from pathlib import Path
 from typing import Any, Dict, List, Optional, Tuple
 
 # updated by scripts/bumpminor.sh
-__version__ = "5.1.12"
+__version__ = "5.2.0"
 
 # ---------------------------------------------------------------------------
 # Protocol  (mirrors hbd/common/proto.py)
@@ -388,7 +388,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
 
     async def _collect_metrics(self) -> Dict[str, Any]:
         results: Dict[str, Any] = {}
-        worst = 0
         for cmd_cfg in self.commands:
             name = cmd_cfg.get("name")
             command = cmd_cfg.get("command")
@@ -399,10 +398,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
             results[f"{name}_status_code"] = rc
             results[f"{name}_output"] = msg
             results.update({f"{name}_{k}": v for k, v in perf.items()})
-            worst = max(worst, rc)
-        results["overall_status"] = _NAGIOS_STATUS.get(worst, "UNKNOWN")
-        results["overall_status_code"] = worst
-        results["plugin_count"] = len(self.commands)
         return results
 
 
@@ -487,6 +482,12 @@ class CPUMonitorPlugin(MonitorPlugin):
         except Exception:
             pass
 
+        try:
+            with open("/proc/uptime") as fh:
+                data["uptime_seconds"] = int(float(fh.read().split()[0]))
+        except Exception:
+            pass
+
         return data
 
 
@@ -535,6 +536,20 @@ class MemoryMonitorPlugin(MonitorPlugin):
         total = mi.get("MemTotal", 0)
         avail = mi.get("MemAvailable", mi.get("MemFree", 0))
         free = mi.get("MemFree", 0)
+
+        # ZFS ARC is reclaimable but not included in MemAvailable; add it.
+        arc_kb = 0
+        try:
+            with open("/proc/spl/kstat/zfs/arcstats") as _f:
+                for _line in _f:
+                    _p = _line.split()
+                    if len(_p) >= 3 and _p[0] == "size":
+                        arc_kb = int(_p[2]) // 1024
+                        break
+        except (OSError, ValueError):
+            pass
+
+        avail = min(avail + arc_kb, total)
         used = total - avail
         data: Dict[str, Any] = {
             "memory_total": total * 1024,
@@ -1052,8 +1067,8 @@ async def _async_main(args, cfg: Dict[str, Any]) -> int:
         if args.message:
             bmsg["service"] = "service"
             bmsg["msg"] = args.message
-        for c in connections:
+        target = next((c for c in connections if c._transport), connections[0])
-            await c.sendto(bmsg)
+        await target.sendto(bmsg)
         if args.message and not args.daemon:
             await asyncio.sleep(0.3)
             for c in connections:
@@ -1066,6 +1081,13 @@ async def _async_main(args, cfg: Dict[str, Any]) -> int:
     for sig in (signal.SIGTERM, signal.SIGINT):
         loop.add_signal_handler(sig, _stop)
 
+    def _sighup():
+        global _dorestart
+        _dorestart = True
+        _stop()
+
+    loop.add_signal_handler(signal.SIGHUP, _sighup)
+
     for conn in connections:
         _active_tasks.append(asyncio.create_task(_heartbeat_sender(conn, interval)))
 
@@ -1078,11 +1100,13 @@ async def _async_main(args, cfg: Dict[str, Any]) -> int:
         pass
 
     log.info("shutting down")
-    for conn in connections:
+    target = next((c for c in connections if c._transport), connections[0] if connections else None)
+    if target:
         try:
-            await conn.sendto({"shutdown": 1, "acks": conn.ackcount})
+            await target.sendto({"shutdown": 1, "acks": target.ackcount})
         except Exception:
             pass
+    for conn in connections:
         conn.close()
     await asyncio.sleep(0.3)
     for plugin in plugins:

test_nagios.py

@@ -68,8 +68,7 @@ async def test_nagios_runner():
     print(f"   ✓ Collected {len(data)} data points")
     
     print(f"\n4. Results:")
-    print(f"   Overall Status: {data.get('overall_status')} (code: {data.get('overall_status_code')})")
+    print(f"   Data points collected: {len(data)}")
-    print(f"   Plugins Executed: {data.get('plugin_count')}")
     
     # Show individual plugin results
     print(f"\n5. Individual Plugin Results:")