homelab-codex-ws/scripts/observer/observer.py

import os
import sys
import json
import time
import glob
import logging
import urllib.request
import urllib.parse
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."""
    tmp = path.with_suffix(".tmp")
    with open(tmp, "w") as f:
        json.dump(data, f, indent=2)
        f.flush()
        os.fsync(f.fileno())
    os.replace(tmp, path)


def _parse_ts(ts) -> float:
    """Return a Unix timestamp float from ts, which may be int/float or an ISO-8601 string.

    Events from node-agent use int(time.time()); events from stability-agent / events.py
    use ISO format ('2026-06-03T10:30:00Z').  Both appear in incident fields such as
    last_occurrence and resolved_at, so any arithmetic on them must go through here.
    Returns 0.0 on None or unparseable input so callers can use plain comparisons.
    """
    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

# Constants and Paths
RUNTIME_PATH = os.getenv("RUNTIME_PATH", "/opt/homelab")
EVENTS_DIR = Path(RUNTIME_PATH) / "events"
STATE_DIR = Path(RUNTIME_PATH) / "state"
LOGS_DIR = Path(RUNTIME_PATH) / "logs"
WORLD_DIR = Path(RUNTIME_PATH) / "world"
OBSERVER_STATE_FILE = STATE_DIR / "observer_checkpoint.json"
FAILED_EVENTS_DIR = STATE_DIR / "observer_failed_events"

REPO_ROOT = Path(__file__).parent.parent.parent
INVENTORY_TOPOLOGY = REPO_ROOT / "inventory" / "topology.yaml"

# --- SHADOW-READ: Prometheus up{} liveness (cutover etap 1) ----------------
# Optional parallel-run source.  When PROM_SHADOW_URL is set, the observer ALSO
# queries Prometheus `up{}` each cycle and LOGS any disagreement with its own
# event-driven liveness — but NEVER acts on it.  The authoritative liveness stays
# 100% event-driven (compute_liveness in _prune_stale_world).  Empty/unset →
# shadow disabled, observer behaves exactly as before (graceful, fail-open).
# Target value (do NOT hardcode — set via env/host override): http://100.95.58.48:9090
PROM_SHADOW_URL = os.environ.get("PROM_SHADOW_URL", "").strip()
PROM_SHADOW_TIMEOUT = int(os.getenv("PROM_SHADOW_TIMEOUT", "5"))

# Logging setup
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
logger = logging.getLogger("observer")

class Observer:
    def __init__(self):
        # Per-node-directory checkpoint: {"vps": "last/file/path", "piha": "last/file/path"}
        # Replaces the old single last_processed_file which silently skipped event dirs
        # that sort alphabetically before the checkpoint (e.g. piha/ < vps/).
        self.node_checkpoints: dict = {}
        self.world_state = {
            "nodes": {},
            "services": {},
            "deployments": {},
            "incidents": {},
            "summary": {
                "last_update": datetime.now(timezone.utc).isoformat(),
                "status": "initializing",
                "active_incidents_count": 0
            }
        }
        self.inventory = self._load_inventory()
        self._ensure_dirs()
        self._load_checkpoint()

    def _ensure_dirs(self):
        WORLD_DIR.mkdir(parents=True, exist_ok=True)
        STATE_DIR.mkdir(parents=True, exist_ok=True)
        EVENTS_DIR.mkdir(parents=True, exist_ok=True)
        LOGS_DIR.mkdir(parents=True, exist_ok=True)
        FAILED_EVENTS_DIR.mkdir(parents=True, exist_ok=True)

    def _quarantine_event_file(self, file_path: str, node_dir: str, exc: Exception) -> None:
        """Move an unreadable/unprocessable event out of the hot path."""
        src = Path(file_path)
        dest_dir = FAILED_EVENTS_DIR / node_dir
        dest_dir.mkdir(parents=True, exist_ok=True)
        dest = dest_dir / src.name
        if dest.exists():
            dest = dest_dir / f"{src.stem}-{int(time.time())}{src.suffix}"
        try:
            os.replace(src, dest)
            logger.error(
                "Quarantined bad event for node_dir=%s: %s -> %s (%s: %s)",
                node_dir, src, dest, type(exc).__name__, exc,
            )
        except Exception as move_exc:
            logger.error(
                "Failed to quarantine bad event for node_dir=%s: %s (%s: %s); move error=%s: %s",
                node_dir, src, type(exc).__name__, exc, type(move_exc).__name__, move_exc,
            )

    def _load_inventory(self):
        inventory = {"nodes": {}, "services": {}}
        try:
            if INVENTORY_TOPOLOGY.exists():
                with open(INVENTORY_TOPOLOGY, "r") as f:
                    topo = yaml.safe_load(f)
                    for node_name, node_info in topo.get("nodes", {}).items():
                        inventory["nodes"][node_name] = {
                            "roles": node_info.get("roles", []),
                            "connectivity": node_info.get("connectivity", {})
                        }
            
            # Load service assignments from hosts files
            hosts_dir = REPO_ROOT / "hosts"
            for host_dir in hosts_dir.iterdir():
                if host_dir.is_dir():
                    svc_file = host_dir / "services.yaml"
                    if svc_file.exists():
                        with open(svc_file, "r") as f:
                            svc_data = yaml.safe_load(f)
                            host_name = svc_data.get("host")
                            for svc_name, svc_info in svc_data.get("services", {}).items():
                                if host_name not in inventory["services"]:
                                    inventory["services"][host_name] = {}
                                inventory["services"][host_name][svc_name] = {
                                    "role": svc_info.get("role"),
                                    "exposure": svc_info.get("exposure")
                                }
        except Exception as e:
            logger.error(f"Failed to load inventory: {e}")
        return inventory

    def _load_checkpoint(self):
        if OBSERVER_STATE_FILE.exists():
            try:
                with open(OBSERVER_STATE_FILE, "r") as f:
                    checkpoint = json.load(f)

                if "node_checkpoints" in checkpoint:
                    # New format: per-directory checkpoints.
                    self.node_checkpoints = checkpoint["node_checkpoints"]
                elif "last_processed_file" in checkpoint:
                    # Migrate old single-file checkpoint: extract node dir from path.
                    old = checkpoint["last_processed_file"]
                    if old:
                        try:
                            node_dir = Path(old).relative_to(EVENTS_DIR).parts[0]
                            self.node_checkpoints = {node_dir: old}
                            logger.info(f"Migrated old checkpoint → node_checkpoints: {self.node_checkpoints}")
                        except Exception:
                            pass  # Bad path — start fresh

                self._load_world_from_disk()
            except Exception as e:
                logger.error(f"Failed to load checkpoint: {e}")

    def _load_world_from_disk(self):
        # Optional: Load existing state to resume faster
        files = {
            "nodes": WORLD_DIR / "nodes.json",
            "services": WORLD_DIR / "services.json",
            "deployments": WORLD_DIR / "deployments.json",
            "incidents": WORLD_DIR / "incidents.json",
            "summary": WORLD_DIR / "runtime-summary.json"
        }
        for key, path in files.items():
            if path.exists():
                try:
                    with open(path, "r") as f:
                        self.world_state[key] = json.load(f)
                except Exception as e:
                    logger.error(f"Failed to load {key} state: {e}")

    def _save_checkpoint(self):
        try:
            _atomic_write_json(OBSERVER_STATE_FILE, {"node_checkpoints": self.node_checkpoints})
        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 _query_prometheus_liveness(self):
        """SHADOW-READ (cutover etap 1): Prometheus up{} → {node_name: up_bool}.

        Parallel-run only: the result is compared against — and logged next to —
        the authoritative event-driven liveness, but NEVER changes it.  See
        PROM_SHADOW_URL.  Returns {} when shadow is disabled OR on ANY error, so
        the observer can never crash or change behaviour because of this call:
        every failure is fail-open (info/warning, never error, never raised).

        Each `up` series is keyed by its `node` label (Prometheus fleet-node
        targets carry node:vps/piha/solaria/lustro).  Series without a node label
        (e.g. the prometheus self-scrape up{job="prometheus"}) are ignored.
        """
        url = PROM_SHADOW_URL
        if not url:
            return {}  # shadow disabled — graceful no-op, observer unchanged
        query_url = url.rstrip("/") + "/api/v1/query?" + urllib.parse.urlencode({"query": "up"})
        try:
            with urllib.request.urlopen(query_url, timeout=PROM_SHADOW_TIMEOUT) as resp:
                payload = json.loads(resp.read().decode("utf-8"))
        except Exception as exc:
            # Fail-open: Prometheus down / timeout / bad JSON → no shadow data.
            # Deliberately NOT logger.error — shadow-read must never look like a
            # critical observer failure.
            logger.warning(
                "shadow-read: Prometheus query failed (%s: %s) — fail-open, "
                "event liveness unaffected", type(exc).__name__, exc,
            )
            return {}
        result: dict = {}
        try:
            for series in payload.get("data", {}).get("result", []):
                node = series.get("metric", {}).get("node")
                if not node:
                    continue  # e.g. up{job="prometheus"} — no node label to map
                value = series.get("value", [None, None])[1]
                result[node] = (value == "1")
        except Exception as exc:
            logger.warning(
                "shadow-read: could not parse Prometheus response (%s: %s) — "
                "fail-open", type(exc).__name__, exc,
            )
            return {}
        return result

    def _shadow_compare_liveness(self, node_name, event_liveness, node_info, prom_map, now):
        """SHADOW-READ comparison (cutover etap 1): log event-vs-Prometheus
        liveness disagreement WITHOUT changing anything.

        Maps both sources onto a shared up/down axis:
          - event DEAD           ≈ prom down
          - event FRESH or STALE ≈ prom up   (STALE = "seen recently, just
            ageing" — still counts as up for this comparison; documented
            assumption of etap 1)

        A node Prometheus doesn't know (no series, e.g. chelsty-infra — not
        scraped) is NOT a mismatch: missing data is not disagreement (debug only).
        This method is read-only w.r.t. liveness/status and must never raise.
        """
        if node_name not in prom_map:
            logger.debug("shadow-read: no prom data for node=%s", node_name)
            return
        prom_up = prom_map[node_name]
        event_up = event_liveness in (FRESH, STALE)
        age = now - _parse_ts(node_info.get("last_seen"))
        if event_up != prom_up:
            logger.info(
                "SHADOW_LIVENESS_MISMATCH node=%s event=%s prom=%s last_seen_age=%.0fs",
                node_name, event_liveness, "up" if prom_up else "down", age,
            )
        else:
            logger.debug(
                "shadow-read agree node=%s event=%s prom=%s last_seen_age=%.0fs",
                node_name, event_liveness, "up" if prom_up else "down", age,
            )

    def _prune_stale_world(self):
        """Remove world-state entries for nodes absent from the topology inventory.

        Root cause this guards against: when NODE_NAME env var is unset, node_agent.py
        falls back to socket.gethostname(), which inside a Docker container returns the
        12-char hex container ID (e.g. 'be17cb6eb0f6') instead of the canonical host name
        ('vps').  The observer ingests those events and creates ghost entries that never
        expire on their own.

        Also ages out resolved incidents older than 7 days to keep world state lean.
        """
        known_nodes = set(self.inventory["nodes"].keys())
        if not known_nodes:
            # Inventory failed to load — don't prune to avoid wiping valid state.
            return

        stale_nodes = [n for n in list(self.world_state["nodes"].keys())
                       if n not in known_nodes]
        for n in stale_nodes:
            logger.info(f"Pruning stale node from world state: {n}")
            del self.world_state["nodes"][n]

        stale_svcs = [k for k in list(self.world_state["services"].keys())
                      if k.split("/")[0] in stale_nodes]
        for k in stale_svcs:
            logger.info(f"Pruning stale service from world state: {k}")
            del self.world_state["services"][k]

        # Prune ghost service keys whose service-name portion is a hash-prefixed
        # Docker stale-state artifact (e.g. "9e36297651e7_control-plane-observer").
        # These are created when node-agent incorrectly uses c.name instead of the
        # compose label, and accumulate on every container rebuild.
        # Pattern: <node>/<12hexchars>_<real-name>
        ghost_svcs = [
            k for k in list(self.world_state["services"].keys())
            if len(k.split("/", 1)) == 2
            and len(k.split("/", 1)[1]) > 13
            and k.split("/", 1)[1][12] == "_"
            and all(ch in "0123456789abcdef" for ch in k.split("/", 1)[1][:12])
        ]
        for k in ghost_svcs:
            logger.info(f"Pruning ghost (hash-prefixed) service key from world state: {k}")
            del self.world_state["services"][k]

        now = time.time()

        # --- 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.
        #
        # SHADOW-READ (cutover etap 1): fetch Prometheus up{} ONCE per cycle
        # (before the node loop, not per-node) for comparison-only logging.  {}
        # when disabled/unreachable — fail-open, event liveness is authoritative.
        prom_liveness_map = self._query_prometheus_liveness()
        for node_name, node_info in self.world_state["nodes"].items():
            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
            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)
            # SHADOW-READ (cutover etap 1): compare (log-only) the event-derived
            # `liveness` computed above against Prometheus up{}.  Purely additive —
            # does NOT read back or mutate node_info["liveness"]/["status"], and
            # the authoritative decision above is already committed.
            self._shadow_compare_liveness(node_name, liveness, node_info, prom_liveness_map, now)

        try:
            # Collect incident_ids currently referenced by any service entry.
            linked_ids: set = {
                svc.get("incident_id")
                for svc in self.world_state["services"].values()
                if svc.get("incident_id")
            }

            # Case 1 — service is healthy but still points at an active incident.
            # process_event already calls _resolve_incident on service_healthy events,
            # but if the observer restarted with on-disk state where the link was
            # intact (inconsistency from a pre-atomic-write crash), it may not get
            # resolved until the next service_healthy event is processed.  Resolve
            # immediately — a healthy service cannot have an ongoing incident.
            for svc_key, svc in self.world_state["services"].items():
                if svc.get("status") != "healthy":
                    continue
                inc_id = svc.get("incident_id")
                if not inc_id:
                    continue
                inc = self.world_state["incidents"].get(inc_id, {})
                if inc.get("status") == "active":
                    logger.info(
                        f"Auto-resolving incident {inc_id} for {svc_key}: "
                        f"service is healthy"
                    )
                    inc["status"] = "resolved"
                    inc["resolved_at"] = now
                    svc["incident_id"] = None
                    linked_ids.discard(inc_id)

            # Case 2 — orphaned active incident: no service entry links to it and
            # last_occurrence is older than 5 minutes (guard against creation races).
            # These are the stale records left behind when on-disk state was
            # inconsistent: the service entry had incident_id cleared but incidents.json
            # still had the record as "active".
            for inc_id, inc in self.world_state["incidents"].items():
                if inc.get("status") != "active":
                    continue
                if inc_id in linked_ids:
                    continue
                age = now - _parse_ts(inc.get("last_occurrence"))
                if age > 300:  # 5-minute guard
                    logger.info(
                        f"Auto-resolving orphaned incident {inc_id} "
                        f"(service={inc.get('service')}, node={inc.get('node')}): "
                        f"no service references it, age={int(age)}s"
                    )
                    inc["status"] = "resolved"
                    inc["resolved_at"] = now

        except Exception as exc:
            logger.error(f"Error during incident auto-resolve in _prune_stale_world: {exc}")

        # Remove resolved incidents older than 7 days.
        # Use _parse_ts so ISO-string resolved_at values are handled correctly.
        stale_incidents = [
            k for k, v in self.world_state["incidents"].items()
            if v.get("status") == "resolved"
            and now - _parse_ts(v.get("resolved_at")) > 7 * 86400
        ]
        for k in stale_incidents:
            del self.world_state["incidents"][k]

    def _save_world(self):
        self.world_state["summary"]["last_update"] = datetime.now(timezone.utc).isoformat()
        active_incidents = [
            k for k, v in self.world_state["incidents"].items() if v.get("status") == "active"
        ]
        self.world_state["summary"]["active_incidents_count"] = len(active_incidents)
        self.world_state["summary"]["node_count"] = len(self.world_state["nodes"])
        self.world_state["summary"]["service_count"] = len(self.world_state["services"])

        if active_incidents:
            self.world_state["summary"]["status"] = "degraded"
        else:
            self.world_state["summary"]["status"] = "nominal"

        files = {
            "nodes.json": self.world_state["nodes"],
            "services.json": self.world_state["services"],
            "deployments.json": self.world_state["deployments"],
            "incidents.json": self.world_state["incidents"],
            "recommendations.json": [],
            "runtime-summary.json": self.world_state["summary"]
        }
        for filename, data in files.items():
            try:
                _atomic_write_json(WORLD_DIR / filename, data)
            except Exception as e:
                logger.error(f"Failed to save {filename}: {e}")

    def process_event(self, event):
        etype = event.get("type")
        node = event.get("node")
        service = event.get("service")
        severity = event.get("severity")
        timestamp = event.get("timestamp")
        cid = event.get("correlation_id")
        payload = event.get("payload", {})

        # 1. Update Node State
        if node not in self.world_state["nodes"]:
            self.world_state["nodes"][node] = {
                "status": "unknown",
                "last_seen": None,
                "roles": self.inventory["nodes"].get(node, {}).get("roles", [])
            }
        self.world_state["nodes"][node]["last_seen"] = timestamp

        if etype == "node_online":
            self.world_state["nodes"][node]["status"] = "online"
        elif etype == "node_offline":
            self.world_state["nodes"][node]["status"] = "offline"

        elif etype == "node_health":
            # Regular heartbeat from node-agent; updates resource metrics.
            # Clears disk_pressure if disk is now healthy (< warn threshold).
            self.world_state["nodes"][node]["status"] = "online"
            self.world_state["nodes"][node].update({
                "disk_usage_pct": payload.get("disk_pct"),
                "mem_usage_pct":  payload.get("mem_pct"),
                "cpu_usage_pct":  payload.get("cpu_pct"),
            })
            if (payload.get("disk_pct") or 0) < 75:
                self.world_state["nodes"][node].pop("disk_pressure", None)

        elif etype == "disk_pressure":
            # Emitted when disk usage crosses 75 % (medium) or 85 % (high).
            # The supervisor reads disk_pressure to generate disk_cleanup actions.
            self.world_state["nodes"][node]["disk_pressure"] = severity
            self.world_state["nodes"][node]["disk_usage_pct"] = payload.get("usage_pct")

        elif etype == "high_memory":
            # Memory pressure observation; recorded on the node for correlation.
            # No automated action — operator decides if a container restart helps.
            self.world_state["nodes"][node]["memory_pressure"] = severity
            self.world_state["nodes"][node]["mem_usage_pct"] = payload.get("usage_pct")

        elif etype == "high_cpu":
            # CPU pressure observation; recorded for visibility.
            self.world_state["nodes"][node]["cpu_pressure"] = severity
            self.world_state["nodes"][node]["cpu_usage_pct"] = payload.get("usage_pct")

        # 2. Update Service State
        if service and service != "all":
            svc_key = f"{node}/{service}"
            if svc_key not in self.world_state["services"]:
                self.world_state["services"][svc_key] = {
                    "node": node,
                    "service": service,
                    "status": "unknown",
                    "last_check": None,
                    "incident_id": None
                }
            self.world_state["services"][svc_key]["last_check"] = timestamp

            if etype == "service_recovered":
                self.world_state["services"][svc_key]["status"] = "healthy"
                self._resolve_incident(svc_key, timestamp)
            elif etype == "service_healthy":
                # Positive confirmation from node-agent that a managed container
                # is running. This keeps services.json populated so the supervisor
                # can correctly detect drift (absent entry = never reported = unknown,
                # not the same as confirmed missing).
                # Also resolve any active incident — if a service that had been
                # unhealthy/crashing is now confirmed healthy, the incident is over.
                self.world_state["services"][svc_key]["status"] = "healthy"
                self._resolve_incident(svc_key, timestamp)
            elif etype in ["service_unhealthy", "healthcheck_failed"]:
                self.world_state["services"][svc_key]["status"] = "unhealthy"
                self._handle_incident(svc_key, event)

        # 3. Update Deployment State
        if etype.startswith("deployment_") and cid:
            if cid not in self.world_state["deployments"]:
                self.world_state["deployments"][cid] = {
                    "node": node,
                    "service": service,
                    "status": "unknown",
                    "started_at": None,
                    "finished_at": None,
                    "events": []
                }
            self.world_state["deployments"][cid]["events"].append({
                "type": etype,
                "timestamp": timestamp,
                "payload": payload
            })
            if etype == "deployment_started":
                self.world_state["deployments"][cid]["status"] = "in_progress"
                self.world_state["deployments"][cid]["started_at"] = timestamp
            elif etype == "deployment_completed":
                self.world_state["deployments"][cid]["status"] = "completed"
                self.world_state["deployments"][cid]["finished_at"] = timestamp
            elif etype == "deployment_failed":
                self.world_state["deployments"][cid]["status"] = "failed"
                self.world_state["deployments"][cid]["finished_at"] = timestamp
                # Deployment failure often creates an incident
                self._handle_deployment_failure(event)

    def _handle_incident(self, svc_key, event):
        # Correlation: collapse repeated failures for the same service on the same node
        active_incident = self.world_state["services"][svc_key].get("incident_id")
        
        if active_incident and active_incident in self.world_state["incidents"]:
            incident = self.world_state["incidents"][active_incident]
            if incident["status"] == "active":
                incident["last_occurrence"] = event["timestamp"]
                incident["occurrence_count"] = incident.get("occurrence_count", 1) + 1
                incident["events"].append(event["timestamp"])
                return

        # Create new incident
        incident_id = f"inc-{int(time.time())}-{event.get('node')}-{event.get('service')}"
        self.world_state["incidents"][incident_id] = {
            "id": incident_id,
            "node": event.get("node"),
            "service": event.get("service"),
            "status": "active",
            "severity": event.get("severity"),
            # trigger_type records the event type that opened this incident so that
            # the supervisor can choose the appropriate remediation action
            # (e.g. container_restart for containers_not_running / mqtt_unreachable
            # vs. a full redeploy for other causes).
            "trigger_type": event.get("type"),
            "started_at": event.get("timestamp"),
            "last_occurrence": event.get("timestamp"),
            "occurrence_count": 1,
            "events": [event["timestamp"]],
            "correlation_id": event.get("correlation_id")
        }
        self.world_state["services"][svc_key]["incident_id"] = incident_id

    def _resolve_incident(self, svc_key, timestamp):
        incident_id = self.world_state["services"][svc_key].get("incident_id")
        if incident_id and incident_id in self.world_state["incidents"]:
            if self.world_state["incidents"][incident_id]["status"] == "active":
                self.world_state["incidents"][incident_id]["status"] = "resolved"
                self.world_state["incidents"][incident_id]["resolved_at"] = timestamp
        self.world_state["services"][svc_key]["incident_id"] = None

    def _handle_deployment_failure(self, event):
        # Specific logic for deployment failures
        svc_key = f"{event.get('node')}/{event.get('service')}"
        self._handle_incident(svc_key, event)
        
        # Link diagnostics if available in payload
        incident_id = self.world_state["services"][svc_key].get("incident_id")
        if incident_id and incident_id in self.world_state["incidents"]:
            payload = event.get("payload", {})
            if "diagnostics_file" in payload:
                self.world_state["incidents"][incident_id]["diagnostics_ref"] = payload["diagnostics_file"]
            elif "error" in payload:
                self.world_state["incidents"][incident_id]["last_error"] = payload["error"]

    def run_once(self):
        # Update heartbeat
        heartbeat_file = STATE_DIR / "observer.heartbeat"
        try:
            heartbeat_file.touch()
        except Exception as e:
            logger.error(f"Failed to touch heartbeat file: {e}")

        # Collect all event files grouped by node directory.
        # Per-node checkpoints are compared within each directory independently,
        # so late-arriving events from remote nodes (sorted earlier in the path)
        # are never skipped just because another node's checkpoint is further ahead.
        all_files = sorted(glob.glob(str(EVENTS_DIR / "**" / "*.json"), recursive=True))

        new_files = []
        for file_path in all_files:
            try:
                node_dir = str(Path(file_path).relative_to(EVENTS_DIR).parts[0])
            except (IndexError, ValueError):
                node_dir = "__unknown__"
            last_for_node = self.node_checkpoints.get(node_dir, "")
            if file_path > last_for_node:
                new_files.append((node_dir, file_path))

        if not new_files:
            # Even if no new events, prune stale entries and refresh summary freshness.
            self._prune_stale_world()
            self._save_world()
            return

        logger.info(f"Processing {len(new_files)} new events across "
                    f"{len({n for n, _ in new_files})} node(s)")
        for node_dir, file_path in new_files:
            try:
                with open(file_path, "r") as f:
                    event = json.load(f)
                # 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
            except Exception as e:
                logger.error(
                    "Error processing node_dir=%s file=%s (%s: %s)",
                    node_dir, file_path, type(e).__name__, e,
                )
                self._quarantine_event_file(file_path, node_dir, e)

        self._save_checkpoint()
        self._prune_stale_world()
        self._save_world()

    def loop(self, interval=5):
        logger.info("Starting observer loop")
        while True:
            self.run_once()
            time.sleep(interval)

if __name__ == "__main__":
    import sys
    observer = Observer()
    if "--run-once" in sys.argv:
        observer.run_once()
    else:
        observer.loop()