diff --git a/docs/observer-runtime.md b/docs/observer-runtime.md
index fd65653..ab57a79 100644
--- a/docs/observer-runtime.md
+++ b/docs/observer-runtime.md
@@ -52,6 +52,42 @@ A single global checkpoint (`last_processed_file`) was replaced with this per-no
 - `node_online`, `node_offline` — update node status in nodes.json
 - `disk_pressure_*` — set `disk_pressure` field on the node record
 
+## Node Liveness (TTL)
+
+Node `status` is derived from **freshness**, not from the last status event.
+Every reconcile cycle (`_prune_stale_world`, runs even with no new events) the
+observer computes `now - last_seen` per node and classifies it:
+
+| tier | age (always-on) | age (remote / LTE) | status written | panel health |
+|---|---|---|---|---|
+| fresh | ≤ 180 s | ≤ 900 s | `online` | nominal |
+| stale | 180–600 s | 900–3600 s | `stale` | degraded |
+| dead | > 600 s | > 3600 s | `offline` | error |
+| unknown | `last_seen` missing | — | (unchanged) | (unchanged) |
+
+Thresholds (tied to the 60 s node-agent heartbeat: fresh = 3× interval) live in
+**one place**: `services/control-plane/src/liveness.py`, imported by the observer
+and both operator UIs (`compute_liveness` / `ttls_for` / `node_health`). Remote
+nodes (topology role `remote`, or `chelsty-*`) use the wider TTLs above.
+Override via env: `LIVENESS_TTL_FRESH`, `LIVENESS_TTL_DEAD`,
+`LIVENESS_REMOTE_TTL_FRESH`, `LIVENESS_REMOTE_TTL_DEAD`.
+
+This fixes the "dead node shown NOMINAL" silent outage: previously `status`
+stayed `online` forever because the only thing that flipped it to offline was a
+`node_offline` event, which a crashed/partitioned node can never emit.
+
+**Transitions** are not silent. On crossing a boundary the observer writes an
+event (`node_stale`, `node_offline`, or `node_online` on recovery) tagged
+`source: "observer"` with the affected node in both `node` and
+`payload.affected_node`. These are **skipped on re-ingest** (so they never reset
+`last_seen`) and routed by the supervisor to `alert_only` actions (Telegram).
+
+**Read-time safety net:** both operator UIs recompute liveness from `last_seen`
+at request time using the same helper, so even a *stalled observer* (frozen
+`nodes.json`) still surfaces a dead node. Services inherit their node's liveness
+(a service on a dead/stale node is never shown nominal) — computed read-time,
+`services.json` is not mutated.
+
 ## Incident Lifecycle
 
 1.  **Detection**: A `service_unhealthy` or `healthcheck_failed` event creates or increments an active incident.
diff --git a/scripts/observer/observer.py b/scripts/observer/observer.py
index dd6ee84..0ecfaa1 100644
--- a/scripts/observer/observer.py
+++ b/scripts/observer/observer.py
@@ -1,4 +1,5 @@
 import os
+import sys
 import json
 import time
 import glob
@@ -7,6 +8,23 @@ import yaml
 from datetime import datetime, timezone
 from pathlib import Path
 
+# Shared liveness logic (thresholds + fresh/stale/dead state machine) lives in
+# the control-plane src so the observer and both operator UIs agree on what
+# "dead" means.  Added to sys.path relative to this file (works both in the
+# container, where the repo is mounted at /repo, and in the test tree).
+_CP_SRC = Path(__file__).resolve().parent.parent.parent / "services" / "control-plane" / "src"
+if str(_CP_SRC) not in sys.path:
+    sys.path.insert(0, str(_CP_SRC))
+from liveness import (  # noqa: E402
+    compute_liveness,
+    ttls_for,
+    liveness_to_status,
+    FRESH,
+    STALE,
+    DEAD,
+    UNKNOWN,
+)
+
 
 def _atomic_write_json(path: Path, data) -> None:
     """Write JSON atomically: write to a sibling .tmp, fsync, then os.replace."""
@@ -44,9 +62,6 @@ WORLD_DIR = Path(RUNTIME_PATH) / "world"
 OBSERVER_STATE_FILE = STATE_DIR / "observer_checkpoint.json"
 FAILED_EVENTS_DIR = STATE_DIR / "observer_failed_events"
 
-# node_health events arrive every 60 s; 5 missed beats → declare offline
-NODE_OFFLINE_TTL_SECS = int(os.getenv("NODE_OFFLINE_TTL_SECS", "300"))
-
 REPO_ROOT = Path(__file__).parent.parent.parent
 INVENTORY_TOPOLOGY = REPO_ROOT / "inventory" / "topology.yaml"
 
@@ -181,6 +196,63 @@ class Observer:
         except Exception as e:
             logger.error(f"Failed to save checkpoint: {e}")
 
+    def _emit_node_transition(self, node_name, prev, new, node_info, now):
+        """Write an event when a node crosses a liveness boundary.
+
+        Makes liveness transitions visible (panel event feed) and actionable
+        (the supervisor routes node_offline/node_stale to an alert).  Without
+        this the outage would be silent — exactly the failure mode being fixed.
+
+        Recovery (stale/dead → fresh) emits node_online so a node coming back is
+        as visible as it going down.
+
+        The affected node is the top-level ``node`` (so the supervisor can route
+        on it) AND ``payload.affected_node`` — note events.py::emit_event would
+        tag node=gethostname() (the observer host, vps), so the observer writes
+        the event directly instead of using that helper.
+
+        ``source: "observer"`` marks the event so run_once skips re-ingesting it
+        (re-ingestion would reset the node's last_seen and resurrect it).
+        """
+        if new == DEAD:
+            etype, severity = "node_offline", "high"
+        elif new == STALE:
+            etype, severity = "node_stale", "warning"
+        elif new == FRESH and prev in (STALE, DEAD):
+            etype, severity = "node_online", "info"
+        else:
+            return  # not a transition we alert on
+
+        ts = int(now)
+        event_id = f"evt-{node_name}-{ts}-{etype}-node"
+        age = int(now - _parse_ts(node_info.get("last_seen")))
+        event = {
+            "id": event_id,
+            "timestamp": ts,
+            "date": datetime.now(timezone.utc).isoformat(),
+            "type": etype,
+            "severity": severity,
+            "node": node_name,
+            "service": None,
+            "source": "observer",
+            "message": f"Node {node_name} liveness {prev} -> {new} (last_seen {age}s ago)",
+            "payload": {
+                "affected_node": node_name,
+                "from": prev,
+                "to": new,
+                "last_seen": node_info.get("last_seen"),
+                "age_secs": age,
+            },
+        }
+        try:
+            node_dir = EVENTS_DIR / node_name
+            node_dir.mkdir(parents=True, exist_ok=True)
+            _atomic_write_json(node_dir / f"{event_id}.json", event)
+            logger.warning("Node %s transition %s -> %s (emitted %s)",
+                           node_name, prev, new, etype)
+        except Exception as exc:
+            logger.error("Failed to emit node transition for %s: %s", node_name, exc)
+
     def _prune_stale_world(self):
         """Remove world-state entries for nodes absent from the topology inventory.
 
@@ -227,21 +299,31 @@ class Observer:
 
         now = time.time()
 
-        # Mark nodes offline when last_seen exceeds NODE_OFFLINE_TTL_SECS.
-        # Handles crash/network-partition cases where node_offline is never emitted.
+        # --- Authoritative node liveness (fresh / stale / dead) -------------
+        # Status is derived from how long ago the node last reported, NOT from
+        # the last status event.  This runs every cycle (including cycles with
+        # no new events — see run_once), so a node that silently stops sending
+        # heartbeats transitions on its own without any node_offline event ever
+        # being emitted.  This is the fix for the "dead node shown NOMINAL"
+        # class of silent outage.
         for node_name, node_info in self.world_state["nodes"].items():
-            if node_info.get("status") != "online":
+            roles = (node_info.get("roles")
+                     or self.inventory["nodes"].get(node_name, {}).get("roles", []))
+            liveness = compute_liveness(
+                node_info.get("last_seen"), now=now, ttls=ttls_for(node_name, roles)
+            )
+            if liveness == UNKNOWN:
+                # No last_seen yet — don't guess a node dead. Leave status as-is.
                 continue
-            last_seen = _parse_ts(node_info.get("last_seen"))
-            if last_seen == 0.0:
-                continue  # Never reported — keep status unknown, don't flip
-            age = now - last_seen
-            if age > NODE_OFFLINE_TTL_SECS:
-                logger.warning(
-                    "Node %s last seen %ds ago (> TTL %ds) — marking offline",
-                    node_name, int(age), NODE_OFFLINE_TTL_SECS,
-                )
-                node_info["status"] = "offline"
+            prev = node_info.get("liveness")
+            node_info["liveness"] = liveness
+            new_status = liveness_to_status(liveness)
+            if new_status:
+                node_info["status"] = new_status
+            # Emit on a real transition only.  prev is None on the very first
+            # classification after (re)start — that is a baseline, not an event.
+            if prev is not None and prev != liveness:
+                self._emit_node_transition(node_name, prev, liveness, node_info, now)
 
         try:
             # Collect incident_ids currently referenced by any service entry.
@@ -535,7 +617,16 @@ class Observer:
             try:
                 with open(file_path, "r") as f:
                     event = json.load(f)
-                    self.process_event(event)
+                # Skip events the observer emitted itself (node liveness
+                # transitions).  Re-ingesting them would call process_event,
+                # which sets last_seen = event timestamp and would resurrect a
+                # node we just declared dead.  They are still consumed by the
+                # supervisor (alerting) and the panel event feed.
+                if event.get("source") == "observer":
+                    if file_path > self.node_checkpoints.get(node_dir, ""):
+                        self.node_checkpoints[node_dir] = file_path
+                    continue
+                self.process_event(event)
                 # Advance per-node checkpoint (only forward — no regression).
                 if file_path > self.node_checkpoints.get(node_dir, ""):
                     self.node_checkpoints[node_dir] = file_path
diff --git a/services/agent-system/docker-compose.yml b/services/agent-system/docker-compose.yml
index f8ef1c0..dcb0e77 100644
--- a/services/agent-system/docker-compose.yml
+++ b/services/agent-system/docker-compose.yml
@@ -13,6 +13,10 @@ services:
       - "18180:8080"
     volumes:
       - /opt/homelab:/opt/homelab
+      # Shared liveness logic — single source of truth, bind-mounted read-only
+      # so this image does not carry a second copy of the thresholds/tier logic.
+      # web.py imports it defensively; absence degrades to observer status only.
+      - ../control-plane/src/liveness.py:/app/liveness.py:ro
     depends_on:
       - redis
     restart: unless-stopped
diff --git a/services/agent-system/webui/web.py b/services/agent-system/webui/web.py
index 6833da5..a380f6f 100644
--- a/services/agent-system/webui/web.py
+++ b/services/agent-system/webui/web.py
@@ -5,6 +5,18 @@ from datetime import datetime, timezone
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from pathlib import Path
 
+# Shared liveness logic — the SAME module the observer and operator_ui use, so
+# all three agree on what "dead" means.  This image only copies web.py +
+# index.html, so liveness.py is bind-mounted in at /app/liveness.py (see this
+# service's docker-compose.yml).  Imported defensively: if the mount is missing
+# we fall back to trusting the observer-written status rather than crashing the
+# whole panel — the observer remains authoritative either way.
+try:
+    from liveness import compute_liveness, ttls_for, node_health as _liveness_health, degrade_for_node
+    _LIVENESS_OK = True
+except Exception:  # pragma: no cover - only when liveness.py mount is absent
+    _LIVENESS_OK = False
+
 
 STATE_DIR = Path(os.getenv("HOMELAB_STATE_ROOT", "/opt/homelab/state"))
 EVENTS_DIR = Path(os.getenv("HOMELAB_EVENTS_ROOT", "/opt/homelab/events"))
@@ -47,12 +59,78 @@ def save_config(config):
     (STATE_DIR / "operator-config.json").write_text(json.dumps(config, indent=2))
 
 
+def _node_liveness_map():
+    """Return {node_name: liveness_tier} from nodes.json (empty if unavailable)."""
+    if not _LIVENESS_OK:
+        return {}
+    raw = read_json_file(WORLD_DIR / "nodes.json", default={})
+    if not isinstance(raw, dict):
+        return {}
+    return {
+        name: compute_liveness(info.get("last_seen"),
+                               ttls=ttls_for(name, info.get("roles", [])))
+        for name, info in raw.items()
+    }
+
+
 def current_nodes():
-    return read_json_file(WORLD_DIR / "nodes.json")
+    """Nodes shaped as a list with a freshness-aware health field.
+
+    nodes.json is a dict keyed by name; index.html does nodes.map() and reads
+    node.health, so we shape to a list and compute health here.  The health is
+    the read-time safety net (worse of persisted status and last_seen
+    freshness) so a stalled observer cannot make a dead node look nominal.
+    """
+    raw = read_json_file(WORLD_DIR / "nodes.json", default={})
+    if isinstance(raw, list):
+        return raw
+    result = []
+    for name, info in raw.items():
+        health = _liveness_health(info, name=name) if _LIVENESS_OK else (
+            "error" if info.get("status") == "offline"
+            else "nominal" if info.get("status") == "online" else info.get("status", "unknown")
+        )
+        result.append({
+            "id":             name,
+            "hostname":       name,
+            "health":         health,
+            "status":         info.get("status", "unknown"),
+            "capabilities":   info.get("roles", []),
+            "connectivity":   "tailscale",
+            "incidents":      0,
+            "last_seen":      info.get("last_seen"),
+            "disk_usage_pct": info.get("disk_usage_pct"),
+            "mem_usage_pct":  info.get("mem_usage_pct"),
+            "cpu_usage_pct":  info.get("cpu_usage_pct"),
+            "disk_pressure":  info.get("disk_pressure"),
+        })
+    return result
 
 
 def current_services():
-    return read_json_file(WORLD_DIR / "services.json")
+    """Services shaped as a list, with the node-liveness cascade (variant B)."""
+    raw = read_json_file(WORLD_DIR / "services.json", default={})
+    if isinstance(raw, list):
+        return raw
+    node_liveness = _node_liveness_map()
+    result = []
+    for key, info in raw.items():
+        svc_status = info.get("status", "unknown")
+        health = ("nominal" if svc_status == "healthy"
+                  else ("error" if svc_status == "unhealthy" else svc_status))
+        node_name = info.get("node", "")
+        if _LIVENESS_OK and node_name in node_liveness:
+            health = degrade_for_node(health, node_liveness[node_name])
+        result.append({
+            "id":           key,
+            "name":         info.get("service", key),
+            "node":         node_name,
+            "health":       health,
+            "actual_state": svc_status,
+            "last_check":   info.get("last_check"),
+            "incident_id":  info.get("incident_id"),
+        })
+    return result
 
 
 def current_deployments():
diff --git a/services/control-plane/src/liveness.py b/services/control-plane/src/liveness.py
new file mode 100644
index 0000000..212604a
--- /dev/null
+++ b/services/control-plane/src/liveness.py
@@ -0,0 +1,151 @@
+"""Shared node-liveness logic — single source of truth for freshness.
+
+This module owns the fresh/stale/dead state machine and its TTL thresholds.
+It is imported by every component that has to decide whether a node is alive:
+
+  - scripts/observer/observer.py          authoritative writer of world/nodes.json
+  - services/control-plane/src/operator_ui.py    read-time safety net (panel)
+  - services/agent-system/webui/web.py           read-time safety net (panel);
+        this file is bind-mounted into the webui image at /app/liveness.py —
+        see services/agent-system/docker-compose.yml.
+
+Why a single module: the previous bug ("dead node shown NOMINAL") was a missing
+TTL.  Thresholds and the tier logic must live in exactly one place so the
+observer and both panels can never disagree about what "dead" means.
+
+Heartbeat interval is 60 s on every node (node-agent CHECK_INTERVAL=60), so the
+fresh ceiling is 3× the interval.  If the interval ever changes, raise the
+thresholds here proportionally and nothing else needs to move.
+"""
+from __future__ import annotations
+
+import os
+import time
+from datetime import datetime
+
+# --- Liveness tiers ---------------------------------------------------------
+FRESH = "fresh"
+STALE = "stale"
+DEAD = "dead"
+UNKNOWN = "unknown"
+
+# --- TTL thresholds (seconds) ----------------------------------------------
+# Always-on nodes (vps/piha/solaria/lustro): heartbeat every 60 s.
+#   fresh ≤ 180 s  → 3 missed beats tolerated (+ observer cycle + rsync latency)
+#   dead  > 600 s  → 10 missed beats == really gone
+DEFAULT_TTLS = {
+    "fresh": int(os.getenv("LIVENESS_TTL_FRESH", "180")),
+    "dead": int(os.getenv("LIVENESS_TTL_DEAD", "600")),
+}
+# Remote / LTE nodes (chelsty-*): intermittent uplink, events buffer locally
+# and ship on reconnect.  Wider so a typical multi-minute LTE blip reads as
+# stale (degraded), but a genuine outage still escalates to dead within an hour.
+REMOTE_TTLS = {
+    "fresh": int(os.getenv("LIVENESS_REMOTE_TTL_FRESH", "900")),   # 15 min
+    "dead": int(os.getenv("LIVENESS_REMOTE_TTL_DEAD", "3600")),    # 1 h
+}
+# A node uses REMOTE_TTLS if its topology role is in REMOTE_ROLES, or its name
+# is in REMOTE_NODES (fallback when roles are absent from the node record).
+REMOTE_ROLES = {"remote"}
+REMOTE_NODES = {"chelsty-infra", "chelsty-ha"}
+
+# --- Mappings ---------------------------------------------------------------
+# Persisted node.status string written by the observer for each tier.
+# UNKNOWN intentionally has no mapping: never overwrite status when we have no
+# timing data (last_seen missing) — we don't guess a node dead.
+_LIVENESS_TO_STATUS = {FRESH: "online", STALE: "stale", DEAD: "offline"}
+# UI health bucket per liveness tier and per persisted status.
+_LIVENESS_HEALTH = {FRESH: "nominal", STALE: "degraded", DEAD: "error", UNKNOWN: "unknown"}
+_STATUS_HEALTH = {"online": "nominal", "stale": "degraded", "offline": "error"}
+# Severity ordering for "take the worse of two health buckets".
+_HEALTH_RANK = {"nominal": 0, "unknown": 1, "degraded": 2, "error": 3}
+
+
+def parse_ts(ts):
+    """Epoch float from int/float or ISO-8601 string; 0.0 on None/garbage.
+
+    node-agent emits int(time.time()); events.py / stability-agent emit ISO
+    strings.  Both land in last_seen, so all arithmetic goes through here.
+    """
+    if ts is None:
+        return 0.0
+    if isinstance(ts, (int, float)):
+        return float(ts)
+    try:
+        return datetime.fromisoformat(str(ts).replace("Z", "+00:00")).timestamp()
+    except Exception:
+        return 0.0
+
+
+def ttls_for(node_name=None, roles=None):
+    """Pick the TTL set for a node by its name or topology roles."""
+    roles = set(roles or ())
+    if (node_name in REMOTE_NODES) or (roles & REMOTE_ROLES):
+        return REMOTE_TTLS
+    return DEFAULT_TTLS
+
+
+def compute_liveness(last_seen, now=None, ttls=None):
+    """Classify a node from age = now - last_seen.
+
+    Returns FRESH / STALE / DEAD, or UNKNOWN when last_seen is missing or
+    unparseable (no data → no opinion; callers must not flip status on UNKNOWN).
+    """
+    ttls = ttls or DEFAULT_TTLS
+    ts = parse_ts(last_seen)
+    if ts <= 0:
+        return UNKNOWN
+    age = (now if now is not None else time.time()) - ts
+    if age <= ttls["fresh"]:
+        return FRESH
+    if age <= ttls["dead"]:
+        return STALE
+    return DEAD
+
+
+def liveness_to_status(liveness):
+    """Persisted node.status for a tier, or None for UNKNOWN (leave as-is)."""
+    return _LIVENESS_TO_STATUS.get(liveness)
+
+
+def _worse(a, b):
+    """Return the more severe of two UI health buckets."""
+    return a if _HEALTH_RANK.get(a, 1) >= _HEALTH_RANK.get(b, 1) else b
+
+
+def node_health(info, name=None, now=None):
+    """UI health bucket for a node record, applying the read-time freshness net.
+
+    Takes the WORSE of (a) the observer-persisted status and (b) the freshness
+    derived from last_seen.  Rationale:
+      - if the observer is alive it already wrote the right status; freshness
+        agrees and this is a no-op.
+      - if the observer itself is dead, nodes.json freezes with stale "online"
+        statuses — but last_seen keeps ageing, so freshness still surfaces the
+        outage.  This is the whole point of duplicating the check at read time.
+    UNKNOWN freshness (no last_seen) never downgrades a node.
+    """
+    stored_health = _STATUS_HEALTH.get(info.get("status", "unknown"), "unknown")
+    liveness = compute_liveness(
+        info.get("last_seen"), now=now, ttls=ttls_for(name, info.get("roles", []))
+    )
+    if liveness == UNKNOWN:
+        health = stored_health
+    else:
+        health = _worse(stored_health, _LIVENESS_HEALTH[liveness])
+    if health == "nominal" and info.get("disk_pressure") == "high":
+        return "degraded"
+    return health
+
+
+def degrade_for_node(service_health, node_liveness):
+    """Cascade node liveness onto a service's health (read-time, panel side).
+
+    A service cannot be healthier than the node it runs on: a service on a dead
+    node is error, on a stale node at least degraded.
+    """
+    if node_liveness == DEAD:
+        return "error"
+    if node_liveness == STALE:
+        return _worse(service_health, "degraded")
+    return service_health
diff --git a/services/control-plane/src/operator_ui.py b/services/control-plane/src/operator_ui.py
index bad983f..49ab73e 100644
--- a/services/control-plane/src/operator_ui.py
+++ b/services/control-plane/src/operator_ui.py
@@ -7,6 +7,10 @@ from datetime import datetime
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from pathlib import Path
 
+# Shared liveness logic (same module the observer uses).  This file lives next
+# to operator_ui.py in the control-plane image, so a plain import works.
+from liveness import compute_liveness, ttls_for, node_health as _liveness_health, degrade_for_node
+
 
 STATE_DIR = Path(os.getenv("HOMELAB_STATE_ROOT", "/opt/homelab/state"))
 EVENTS_DIR = Path(os.getenv("HOMELAB_EVENTS_ROOT", "/opt/homelab/events"))
@@ -55,15 +59,15 @@ EVENTS_MAX_AGE_HOURS = int(os.getenv("EVENTS_MAX_AGE_HOURS", "24"))
 EVENTS_MAX_COUNT = int(os.getenv("EVENTS_MAX_COUNT", "200"))
 
 
-def _node_health(info):
-    status = info.get("status", "unknown")
-    if status == "offline":
-        return "error"
-    if info.get("disk_pressure") == "high":
-        return "degraded"
-    if status == "online":
-        return "nominal"
-    return status
+def _node_health(info, name=None):
+    """UI health bucket for a node, with the read-time freshness safety net.
+
+    Delegates to the shared liveness helper: takes the worse of the observer's
+    persisted status and the freshness derived from last_seen, so a stalled
+    observer (frozen nodes.json) still surfaces a dead node as error instead of
+    nominal.  Thresholds live in liveness.py — never here.
+    """
+    return _liveness_health(info, name=name)
 
 
 def current_nodes():
@@ -81,7 +85,7 @@ def current_nodes():
         result.append({
             "id":            name,
             "hostname":      name,
-            "health":        _node_health(info),
+            "health":        _node_health(info, name),
             "status":        info.get("status", "unknown"),
             "capabilities":  info.get("roles", []),
             "connectivity":  "tailscale",
@@ -104,16 +108,34 @@ def current_services():
     raw = read_json_file(WORLD_DIR / "services.json", default={})
     if isinstance(raw, list):
         return raw
+
+    # Read-time cascade (variant B): a service cannot be healthier than the node
+    # it runs on.  Compute each node's liveness from nodes.json (NOT mutating
+    # it) and degrade the service health accordingly.  Without this, a service
+    # on a dead node would still read "nominal" from its last health check.
+    nodes_raw = read_json_file(WORLD_DIR / "nodes.json", default={})
+    node_liveness = {}
+    if isinstance(nodes_raw, dict):
+        for n_name, n_info in nodes_raw.items():
+            node_liveness[n_name] = compute_liveness(
+                n_info.get("last_seen"),
+                ttls=ttls_for(n_name, n_info.get("roles", [])),
+            )
+
     result = []
     for key, info in raw.items():
         svc_status = info.get("status", "unknown")
+        health = ("nominal" if svc_status == "healthy"
+                  else ("error" if svc_status == "unhealthy"
+                        else svc_status))
+        node_name = info.get("node", "")
+        if node_name in node_liveness:
+            health = degrade_for_node(health, node_liveness[node_name])
         result.append({
             "id":               key,
             "name":             info.get("service", key),
-            "node":             info.get("node", ""),
-            "health":           ("nominal" if svc_status == "healthy"
-                                 else ("error" if svc_status == "unhealthy"
-                                       else svc_status)),
+            "node":             node_name,
+            "health":           health,
             "desired_state":    "running",
             "actual_state":     svc_status,
             "deployment_state": "deployed",
diff --git a/services/control-plane/src/supervisor.py b/services/control-plane/src/supervisor.py
index a7db0b4..a9a4d05 100644
--- a/services/control-plane/src/supervisor.py
+++ b/services/control-plane/src/supervisor.py
@@ -85,6 +85,15 @@ HA_ALERT_COOLDOWN = 3600
 # within this window — HA is in a planned restart/update and alerts would be noise.
 HA_TRANSITION_WINDOW = 300  # 5 minutes
 
+# ---------------------------------------------------------------------------
+# Node liveness event routing (observer-emitted node_offline/node_stale/node_online)
+# ---------------------------------------------------------------------------
+# A node we cannot reach cannot be auto-remediated (you can't docker-restart a
+# host that is offline), so these are alert-only — they exist to make a silent
+# outage loud.  node_online is the recovery notice.
+NODE_ALERT_EVENTS = {"node_offline", "node_stale", "node_online"}
+NODE_ALERT_COOLDOWN = 3600  # 1-hour cooldown to avoid repeated Telegram noise
+
 # When True, events that would generate container_restart are downgraded to alert_only
 # with a "[SHADOW MODE]" note. Safe default for initial deployment; set
 # HA_DIAG_SHADOW_MODE=false on the control-plane node when ready for live actions.
@@ -539,7 +548,11 @@ class Supervisor:
             except Exception as e:
                 logger.debug(f"Could not read event {event_file}: {e}")
                 continue
-            if not event.get("type", "").startswith("ha_"):
+            etype = event.get("type", "")
+            if etype in NODE_ALERT_EVENTS:
+                self._route_node_event(event)
+                continue
+            if not etype.startswith("ha_"):
                 continue
             self._route_ha_event(event)
 
@@ -726,6 +739,49 @@ class Supervisor:
         }
         self._write_pending_action(action)
 
+    def _route_node_event(self, event: dict):
+        """Route an observer-emitted node liveness event to an alert_only action.
+
+        node_offline / node_stale make a silent outage loud; node_online is the
+        recovery notice.  No auto-remediation — an unreachable node can't be
+        restarted from here.  Dedup via stable action_id + cooldown, mirroring
+        the HA alert path.
+        """
+        event_type = event.get("type", "")
+        node = event.get("node") or event.get("payload", {}).get("affected_node")
+        if not node:
+            return
+
+        action_id = f"alert-{event_type.replace('_', '-')}-{node}"
+
+        for state in ("pending", "approved", "running"):
+            if (ACTIONS_DIR / state / f"{action_id}.json").exists():
+                logger.debug(f"Skipping {action_id}: already in state '{state}'")
+                return
+
+        if self._ha_action_recently_completed(action_id, NODE_ALERT_COOLDOWN):
+            logger.debug(f"Skipping {action_id}: within {NODE_ALERT_COOLDOWN}s cooldown")
+            return
+
+        payload = dict(event.get("payload", {}))
+        payload["reason"] = event_type
+
+        action = {
+            "action_id": action_id,
+            "timestamp": time.time(),
+            "type": "alert_only",
+            "node": node,
+            "service": None,
+            "risk_level": "info",
+            "confidence": 1.0,
+            "description": event.get(
+                "message", f"Node liveness alert: {event_type} on {node}"
+            ),
+            "status": "pending",
+            "payload": payload,
+        }
+        self._write_pending_action(action)
+
     def _cancel_ha_container_restart(self, node: str):
         """Move a pending ha_websocket_dead container_restart to cancelled on recovery."""
         action_id = f"container-restart-{node}-homeassistant"
diff --git a/services/control-plane/tests/test_incident_lifecycle.py b/services/control-plane/tests/test_incident_lifecycle.py
index 4960519..198f215 100644
--- a/services/control-plane/tests/test_incident_lifecycle.py
+++ b/services/control-plane/tests/test_incident_lifecycle.py
@@ -380,90 +380,193 @@ def test_run_once_quarantines_bad_event_and_processes_next_for_same_node(tmp_pat
 
 
 # ---------------------------------------------------------------------------
-# 7. Node offline TTL — liveness detection via last_seen age
+# 7. Node liveness — 3-state (fresh/stale/dead) authoritative classification
 # ---------------------------------------------------------------------------
+# Default TTLs (liveness.py): fresh <=180s, dead >600s.  "vps" is in the test
+# topology so it survives stale-node pruning.
 
-def test_prune_marks_online_node_offline_after_ttl(tmp_path):
-    """Node online with last_seen > NODE_OFFLINE_TTL_SECS must be flipped to offline."""
+def _node_events(obs_mod, node="vps"):
+    """List event files the observer emitted into <node>/ during a prune."""
+    d = obs_mod.EVENTS_DIR / node
+    return sorted(d.glob("*.json")) if d.exists() else []
+
+
+def test_prune_keeps_fresh_node_online(tmp_path):
     obs = _make_observer_simple(tmp_path)
-    import observer.observer as obs_mod
-
-    # Use "vps" — present in the test topology so it won't be pruned as stale.
     obs.world_state["nodes"]["vps"] = {
-        "status": "online",
-        "last_seen": time.time() - (obs_mod.NODE_OFFLINE_TTL_SECS + 60),  # over TTL
-        "roles": [],
+        "status": "online", "last_seen": time.time() - 60, "roles": [],
     }
-
     obs._prune_stale_world()
-
-    assert obs.world_state["nodes"]["vps"]["status"] == "offline"
-
-
-def test_prune_does_not_mark_node_offline_within_ttl(tmp_path):
-    """Node online with recent last_seen must stay online."""
-    obs = _make_observer_simple(tmp_path)
-    import observer.observer as obs_mod
-
-    obs.world_state["nodes"]["vps"] = {
-        "status": "online",
-        "last_seen": time.time() - (obs_mod.NODE_OFFLINE_TTL_SECS - 60),  # within TTL
-        "roles": [],
-    }
-
-    obs._prune_stale_world()
-
     assert obs.world_state["nodes"]["vps"]["status"] == "online"
+    assert obs.world_state["nodes"]["vps"]["liveness"] == "fresh"
 
 
-def test_prune_does_not_flip_already_offline_node(tmp_path):
-    """Node already offline must not be changed by TTL logic."""
+def test_prune_marks_node_stale_between_ttls(tmp_path):
+    """180s < age <= 600s → stale/degraded, not yet dead."""
     obs = _make_observer_simple(tmp_path)
-
     obs.world_state["nodes"]["vps"] = {
-        "status": "offline",
-        "last_seen": time.time() - 9999,
-        "roles": [],
+        "status": "online", "last_seen": time.time() - 300, "roles": [],
     }
-
     obs._prune_stale_world()
+    assert obs.world_state["nodes"]["vps"]["status"] == "stale"
+    assert obs.world_state["nodes"]["vps"]["liveness"] == "stale"
 
+
+def test_prune_marks_node_dead_after_down_ttl(tmp_path):
+    """age > 600s → dead/offline."""
+    obs = _make_observer_simple(tmp_path)
+    obs.world_state["nodes"]["vps"] = {
+        "status": "online", "last_seen": time.time() - 700, "roles": [],
+    }
+    obs._prune_stale_world()
     assert obs.world_state["nodes"]["vps"]["status"] == "offline"
+    assert obs.world_state["nodes"]["vps"]["liveness"] == "dead"
 
 
-def test_prune_does_not_flip_never_seen_node(tmp_path):
-    """Node with last_seen=None must stay in its original status."""
-    obs = _make_observer_simple(tmp_path)
-
-    obs.world_state["nodes"]["vps"] = {
-        "status": "online",
-        "last_seen": None,
-        "roles": [],
-    }
-
-    obs._prune_stale_world()
-
-    # last_seen=None means we have no data — don't flip to offline
-    assert obs.world_state["nodes"]["vps"]["status"] == "online"
-
-
-def test_prune_marks_node_offline_with_iso_last_seen(tmp_path):
-    """TTL check must work when last_seen is an ISO-8601 string."""
+def test_prune_unknown_when_no_last_seen(tmp_path):
+    """last_seen=None → UNKNOWN: status untouched, no liveness flip, no event."""
     obs = _make_observer_simple(tmp_path)
     import observer.observer as obs_mod
+    obs.world_state["nodes"]["vps"] = {
+        "status": "online", "last_seen": None, "roles": [],
+    }
+    obs._prune_stale_world()
+    assert obs.world_state["nodes"]["vps"]["status"] == "online"
+    assert "liveness" not in obs.world_state["nodes"]["vps"]
+    assert _node_events(obs_mod) == []
 
+
+def test_prune_marks_node_dead_with_iso_last_seen(tmp_path):
+    """3-state classification works when last_seen is an ISO-8601 string."""
+    obs = _make_observer_simple(tmp_path)
     from datetime import datetime, timezone
     stale_ts = datetime.fromtimestamp(
-        time.time() - (obs_mod.NODE_OFFLINE_TTL_SECS + 120),
-        tz=timezone.utc,
+        time.time() - 700, tz=timezone.utc
     ).isoformat()
-
     obs.world_state["nodes"]["vps"] = {
-        "status": "online",
-        "last_seen": stale_ts,
-        "roles": [],
+        "status": "online", "last_seen": stale_ts, "roles": [],
     }
+    obs._prune_stale_world()
+    assert obs.world_state["nodes"]["vps"]["status"] == "offline"
 
+
+# --- Transition emission --------------------------------------------------
+
+def test_transition_emits_node_offline_event(tmp_path):
+    """fresh -> dead emits a node_offline event tagged source=observer."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+    obs.world_state["nodes"]["vps"] = {
+        "status": "online", "liveness": "fresh",
+        "last_seen": time.time() - 700, "roles": [],
+    }
     obs._prune_stale_world()
 
+    events = _node_events(obs_mod)
+    assert len(events) == 1
+    ev = json.loads(events[0].read_text())
+    assert ev["type"] == "node_offline"
+    assert ev["node"] == "vps"
+    assert ev["source"] == "observer"
+    assert ev["payload"]["affected_node"] == "vps"
+    assert ev["payload"]["to"] == "dead"
+
+
+def test_transition_emits_recovery_on_dead_to_fresh(tmp_path):
+    """dead -> fresh emits node_online (recovery is as visible as the fall)."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+    obs.world_state["nodes"]["vps"] = {
+        "status": "offline", "liveness": "dead",
+        "last_seen": time.time() - 10, "roles": [],
+    }
+    obs._prune_stale_world()
+
+    assert obs.world_state["nodes"]["vps"]["status"] == "online"
+    events = _node_events(obs_mod)
+    assert len(events) == 1
+    ev = json.loads(events[0].read_text())
+    assert ev["type"] == "node_online"
+    assert ev["payload"]["from"] == "dead"
+    assert ev["payload"]["to"] == "fresh"
+
+
+def test_no_emission_on_baseline_classification(tmp_path):
+    """First classification (prev liveness=None) is a baseline, not a transition."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+    obs.world_state["nodes"]["vps"] = {
+        "status": "online", "last_seen": time.time() - 700, "roles": [],
+    }
+    obs._prune_stale_world()
+    assert obs.world_state["nodes"]["vps"]["status"] == "offline"  # still classified
+    assert _node_events(obs_mod) == []                              # but no event
+
+
+def test_no_emission_when_liveness_unchanged(tmp_path):
+    """Still-dead node must not re-emit on every cycle."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+    obs.world_state["nodes"]["vps"] = {
+        "status": "offline", "liveness": "dead",
+        "last_seen": time.time() - 5000, "roles": [],
+    }
+    obs._prune_stale_world()
+    assert _node_events(obs_mod) == []
+
+
+def test_remote_node_uses_wider_ttls(tmp_path):
+    """A remote-role node at age 700s is still only stale (remote dead TTL=3600)."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+    # Add chelsty-infra to topology so it survives stale-node pruning.
+    obs_mod.INVENTORY_TOPOLOGY.write_text(
+        "nodes:\n"
+        "  vps:\n    roles: [control-plane]\n    connectivity: {}\n"
+        "  chelsty-infra:\n    roles: [remote, infra]\n    connectivity: {}\n"
+    )
+    obs.inventory = obs._load_inventory()
+    obs.world_state["nodes"]["chelsty-infra"] = {
+        "status": "online", "last_seen": time.time() - 1200,
+        "roles": ["remote", "infra"],
+    }
+    obs._prune_stale_world()
+    # 1200s > default dead (600) but < remote dead (3600) → stale, not dead.
+    assert obs.world_state["nodes"]["chelsty-infra"]["liveness"] == "stale"
+
+
+# --- Observer skips re-ingesting its own transition events ----------------
+
+def test_run_once_skips_observer_emitted_events(tmp_path):
+    """An observer-source event must NOT be re-ingested (would reset last_seen)."""
+    obs = _make_observer_simple(tmp_path)
+    import observer.observer as obs_mod
+
+    vps_dir = obs_mod.EVENTS_DIR / "vps"
+    vps_dir.mkdir(parents=True, exist_ok=True)
+    # Seed world with a dead vps so we can detect an unwanted resurrection.
+    obs.world_state["nodes"]["vps"] = {
+        "status": "offline", "liveness": "dead",
+        "last_seen": time.time() - 5000, "roles": [],
+    }
+    # An observer-emitted node_online event with a fresh timestamp — if it were
+    # ingested, process_event would set last_seen=now and flip vps back online.
+    ev_path = vps_dir / "evt-vps-9999999999-node_online-node.json"
+    ev_path.write_text(json.dumps({
+        "id": "evt-vps-9999999999-node_online-node",
+        "timestamp": int(time.time()),
+        "type": "node_online",
+        "severity": "info",
+        "node": "vps",
+        "service": None,
+        "source": "observer",
+        "message": "synthetic",
+        "payload": {"affected_node": "vps"},
+    }))
+
+    obs.run_once()
+
+    # Not ingested: last_seen stays old → vps stays dead/offline.
     assert obs.world_state["nodes"]["vps"]["status"] == "offline"
+    # Checkpoint still advanced over the skipped file.
+    assert obs.node_checkpoints.get("vps") == str(ev_path)
diff --git a/services/control-plane/tests/test_liveness.py b/services/control-plane/tests/test_liveness.py
new file mode 100644
index 0000000..183050a
--- /dev/null
+++ b/services/control-plane/tests/test_liveness.py
@@ -0,0 +1,137 @@
+"""Unit tests for the shared liveness helper (thresholds + tier state machine)."""
+from __future__ import annotations
+
+import sys
+import time
+from datetime import datetime, timezone
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+import liveness
+from liveness import (
+    compute_liveness,
+    ttls_for,
+    liveness_to_status,
+    node_health,
+    degrade_for_node,
+    parse_ts,
+    FRESH,
+    STALE,
+    DEAD,
+    UNKNOWN,
+)
+
+
+# --- parse_ts ---------------------------------------------------------------
+
+def test_parse_ts_int_float_iso_none():
+    assert abs(parse_ts(1000) - 1000.0) < 0.001
+    assert abs(parse_ts(1000.5) - 1000.5) < 0.001
+    iso = "2026-06-01T00:00:00Z"
+    assert abs(parse_ts(iso) - datetime(2026, 6, 1, tzinfo=timezone.utc).timestamp()) < 1
+    assert parse_ts(None) == 0.0
+    assert parse_ts("garbage") == 0.0
+
+
+# --- compute_liveness (default TTLs: fresh<=180, dead>600) ------------------
+
+def test_compute_liveness_fresh():
+    assert compute_liveness(time.time() - 60) == FRESH
+
+
+def test_compute_liveness_stale():
+    assert compute_liveness(time.time() - 300) == STALE
+
+
+def test_compute_liveness_dead():
+    assert compute_liveness(time.time() - 700) == DEAD
+
+
+def test_compute_liveness_boundaries():
+    now = 1_000_000
+    assert compute_liveness(now - 180, now=now) == FRESH   # exactly fresh ceiling
+    assert compute_liveness(now - 181, now=now) == STALE
+    assert compute_liveness(now - 600, now=now) == STALE   # exactly dead floor
+    assert compute_liveness(now - 601, now=now) == DEAD
+
+
+def test_compute_liveness_unknown_on_missing():
+    assert compute_liveness(None) == UNKNOWN
+    assert compute_liveness("garbage") == UNKNOWN
+    assert compute_liveness(0) == UNKNOWN
+
+
+def test_compute_liveness_iso_string():
+    iso = datetime.fromtimestamp(time.time() - 700, tz=timezone.utc).isoformat()
+    assert compute_liveness(iso) == DEAD
+
+
+# --- ttls_for ---------------------------------------------------------------
+
+def test_ttls_for_default_vs_remote():
+    assert ttls_for("vps", ["control-plane"]) == liveness.DEFAULT_TTLS
+    assert ttls_for("chelsty-infra", []) == liveness.REMOTE_TTLS       # by name
+    assert ttls_for("anything", ["remote"]) == liveness.REMOTE_TTLS    # by role
+
+
+def test_remote_node_stale_where_default_would_be_dead():
+    now = 1_000_000
+    ts = now - 1200  # > default dead (600) and > remote fresh (900), < remote dead (3600)
+    assert compute_liveness(ts, now=now, ttls=ttls_for("chelsty-infra")) == STALE
+    assert compute_liveness(ts, now=now, ttls=ttls_for("vps")) == DEAD
+
+
+# --- liveness_to_status -----------------------------------------------------
+
+def test_liveness_to_status():
+    assert liveness_to_status(FRESH) == "online"
+    assert liveness_to_status(STALE) == "stale"
+    assert liveness_to_status(DEAD) == "offline"
+    assert liveness_to_status(UNKNOWN) is None
+
+
+# --- node_health (read-time safety net) -------------------------------------
+
+def test_node_health_fresh_online_is_nominal():
+    info = {"status": "online", "last_seen": time.time() - 30, "roles": []}
+    assert node_health(info, "vps") == "nominal"
+
+
+def test_node_health_frozen_online_but_dead_is_error():
+    """Observer dead → status frozen 'online' but last_seen old → error (the net)."""
+    info = {"status": "online", "last_seen": time.time() - 700, "roles": []}
+    assert node_health(info, "vps") == "error"
+
+
+def test_node_health_stale_is_degraded():
+    info = {"status": "online", "last_seen": time.time() - 300, "roles": []}
+    assert node_health(info, "vps") == "degraded"
+
+
+def test_node_health_unknown_freshness_does_not_downgrade():
+    info = {"status": "online", "last_seen": None, "roles": []}
+    assert node_health(info, "vps") == "nominal"
+
+
+def test_node_health_disk_pressure_degrades_fresh_node():
+    info = {"status": "online", "last_seen": time.time() - 30,
+            "roles": [], "disk_pressure": "high"}
+    assert node_health(info, "vps") == "degraded"
+
+
+def test_node_health_takes_worse_of_status_and_freshness():
+    # status already offline, freshness fresh → still error (worse wins)
+    info = {"status": "offline", "last_seen": time.time() - 5, "roles": []}
+    assert node_health(info, "vps") == "error"
+
+
+# --- degrade_for_node (service cascade) -------------------------------------
+
+def test_degrade_for_node():
+    assert degrade_for_node("nominal", DEAD) == "error"
+    assert degrade_for_node("nominal", STALE) == "degraded"
+    assert degrade_for_node("nominal", FRESH) == "nominal"
+    # never upgrades a service that is already worse
+    assert degrade_for_node("error", STALE) == "error"
+    assert degrade_for_node("error", FRESH) == "error"
diff --git a/services/control-plane/tests/test_operator_ui_liveness.py b/services/control-plane/tests/test_operator_ui_liveness.py
new file mode 100644
index 0000000..0b95fbc
--- /dev/null
+++ b/services/control-plane/tests/test_operator_ui_liveness.py
@@ -0,0 +1,77 @@
+"""Read-time liveness safety net + service cascade in the operator UI backend."""
+from __future__ import annotations
+
+import json
+import sys
+import time
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+import operator_ui
+
+
+def _setup_world(tmp_path, monkeypatch, nodes, services):
+    world = tmp_path / "world"
+    world.mkdir(parents=True, exist_ok=True)
+    (world / "nodes.json").write_text(json.dumps(nodes))
+    (world / "services.json").write_text(json.dumps(services))
+    monkeypatch.setattr(operator_ui, "WORLD_DIR", world)
+
+
+def test_current_nodes_fresh_is_nominal(tmp_path, monkeypatch):
+    _setup_world(tmp_path, monkeypatch,
+                 {"vps": {"status": "online", "last_seen": time.time() - 30, "roles": []}},
+                 {})
+    nodes = operator_ui.current_nodes()
+    assert nodes[0]["health"] == "nominal"
+
+
+def test_current_nodes_frozen_online_but_dead_is_error(tmp_path, monkeypatch):
+    """The bug: observer wrote 'online' but last_seen is ancient → must be error."""
+    _setup_world(tmp_path, monkeypatch,
+                 {"chelsty-infra": {"status": "online",
+                                    "last_seen": time.time() - 16 * 86400,
+                                    "roles": ["remote"]}},
+                 {})
+    nodes = operator_ui.current_nodes()
+    assert nodes[0]["health"] == "error"
+
+
+def test_current_nodes_stale_is_degraded(tmp_path, monkeypatch):
+    _setup_world(tmp_path, monkeypatch,
+                 {"piha": {"status": "online", "last_seen": time.time() - 300, "roles": []}},
+                 {})
+    nodes = operator_ui.current_nodes()
+    assert nodes[0]["health"] == "degraded"
+
+
+def test_service_cascade_dead_node_makes_service_error(tmp_path, monkeypatch):
+    """A 'healthy' service on a dead node must read error (cascade, read-time)."""
+    _setup_world(
+        tmp_path, monkeypatch,
+        {"piha": {"status": "online", "last_seen": time.time() - 700, "roles": []}},
+        {"piha/vikunja": {"node": "piha", "service": "vikunja", "status": "healthy"}},
+    )
+    svcs = operator_ui.current_services()
+    assert svcs[0]["health"] == "error"
+
+
+def test_service_cascade_stale_node_makes_service_degraded(tmp_path, monkeypatch):
+    _setup_world(
+        tmp_path, monkeypatch,
+        {"piha": {"status": "online", "last_seen": time.time() - 300, "roles": []}},
+        {"piha/vikunja": {"node": "piha", "service": "vikunja", "status": "healthy"}},
+    )
+    svcs = operator_ui.current_services()
+    assert svcs[0]["health"] == "degraded"
+
+
+def test_service_on_fresh_node_stays_nominal(tmp_path, monkeypatch):
+    _setup_world(
+        tmp_path, monkeypatch,
+        {"vps": {"status": "online", "last_seen": time.time() - 30, "roles": []}},
+        {"vps/outline": {"node": "vps", "service": "outline", "status": "healthy"}},
+    )
+    svcs = operator_ui.current_services()
+    assert svcs[0]["health"] == "nominal"
diff --git a/services/control-plane/tests/test_supervisor_ha.py b/services/control-plane/tests/test_supervisor_ha.py
index 78d7b12..a0c98b0 100644
--- a/services/control-plane/tests/test_supervisor_ha.py
+++ b/services/control-plane/tests/test_supervisor_ha.py
@@ -384,7 +384,9 @@ def test_non_ha_events_not_routed(tmp_path, monkeypatch):
     sup = _setup_supervisor(tmp_path, monkeypatch)
     events_dir = tmp_path / "events"
 
-    for etype in ("service_unhealthy", "containers_not_running", "node_online", "deployment_failed"):
+    # node_online/node_offline/node_stale are now routed (node-liveness alerts),
+    # so use only events that are neither ha_* nor node-liveness events here.
+    for etype in ("service_unhealthy", "containers_not_running", "node_health", "deployment_failed"):
         e = _make_event(etype, service="mosquitto")
         e["type"] = etype
         _write_event(events_dir, e)
diff --git a/services/control-plane/tests/test_supervisor_node_events.py b/services/control-plane/tests/test_supervisor_node_events.py
new file mode 100644
index 0000000..659147a
--- /dev/null
+++ b/services/control-plane/tests/test_supervisor_node_events.py
@@ -0,0 +1,122 @@
+"""Supervisor routing of observer-emitted node liveness events → alert_only."""
+from __future__ import annotations
+
+import json
+import sys
+import time
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+import supervisor as supervisor_module
+from supervisor import Supervisor
+
+
+def _setup_supervisor(tmp_path, monkeypatch):
+    actions = tmp_path / "actions"
+    events = tmp_path / "events"
+    world = tmp_path / "world"
+    repo = tmp_path / "repo"
+    state = tmp_path / "state"
+    for d in (actions, events, world, repo / "hosts", state):
+        d.mkdir(parents=True, exist_ok=True)
+    monkeypatch.setattr(supervisor_module, "ACTIONS_DIR", actions)
+    monkeypatch.setattr(supervisor_module, "EVENTS_DIR", events)
+    monkeypatch.setattr(supervisor_module, "WORLD_DIR", world)
+    monkeypatch.setattr(supervisor_module, "REPO_ROOT", repo)
+    sup = Supervisor()
+    sup.desired_state = {"services": {}}
+    sup.actual_state = {"services": {}, "nodes": {}, "incidents": {}}
+    return sup
+
+
+def _node_event(node, etype):
+    return {
+        "id": f"evt-{node}-{int(time.time())}-{etype}-node",
+        "type": etype,
+        "node": node,
+        "service": None,
+        "severity": "high",
+        "timestamp": int(time.time()),
+        "source": "observer",
+        "message": f"Node {node} {etype}",
+        "payload": {"affected_node": node, "from": "fresh", "to": "dead"},
+    }
+
+
+def _write(events_dir, event):
+    p = events_dir / f"{event['id']}.json"
+    p.write_text(json.dumps(event))
+    return p
+
+
+def _pending(tmp_path, action_id):
+    return tmp_path / "actions" / "pending" / f"{action_id}.json"
+
+
+def test_node_offline_generates_alert_only(tmp_path, monkeypatch):
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    _write(tmp_path / "events", _node_event("chelsty-infra", "node_offline"))
+
+    sup._process_ha_events()
+
+    action_id = "alert-node-offline-chelsty-infra"
+    assert _pending(tmp_path, action_id).exists()
+    action = json.loads(_pending(tmp_path, action_id).read_text())
+    assert action["type"] == "alert_only"
+    assert action["node"] == "chelsty-infra"
+    assert action["payload"]["reason"] == "node_offline"
+
+
+def test_node_stale_generates_alert_only(tmp_path, monkeypatch):
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    _write(tmp_path / "events", _node_event("piha", "node_stale"))
+
+    sup._process_ha_events()
+
+    assert _pending(tmp_path, "alert-node-stale-piha").exists()
+
+
+def test_node_online_recovery_generates_alert_only(tmp_path, monkeypatch):
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    _write(tmp_path / "events", _node_event("piha", "node_online"))
+
+    sup._process_ha_events()
+
+    assert _pending(tmp_path, "alert-node-online-piha").exists()
+
+
+def test_node_alert_deduped_within_cooldown(tmp_path, monkeypatch):
+    """A second identical event must not create a second pending action."""
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    _write(tmp_path / "events", _node_event("chelsty-infra", "node_offline"))
+    sup._process_ha_events()
+
+    # Reset the in-memory processed-id set so the file is re-read, but the
+    # action already exists in pending → must be skipped.
+    sup._ha_processed_event_ids.clear()
+    sup._process_ha_events()
+
+    pending = list((tmp_path / "actions" / "pending").glob("*.json"))
+    assert len(pending) == 1
+
+
+def test_node_alert_uses_affected_node_when_top_level_missing(tmp_path, monkeypatch):
+    """If node is absent at top level, fall back to payload.affected_node."""
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    ev = _node_event("solaria", "node_offline")
+    ev["node"] = None
+    _write(tmp_path / "events", ev)
+
+    sup._process_ha_events()
+
+    assert _pending(tmp_path, "alert-node-offline-solaria").exists()
+
+
+def test_non_node_non_ha_event_not_routed(tmp_path, monkeypatch):
+    sup = _setup_supervisor(tmp_path, monkeypatch)
+    ev = _node_event("vps", "node_health")  # not in NODE_ALERT_EVENTS
+    _write(tmp_path / "events", ev)
+
+    sup._process_ha_events()
+
+    assert list((tmp_path / "actions" / "pending").glob("*.json")) == []