Update docs and screenshots

backend/app/telemetry/__init__.py

@@ -0,0 +1,2 @@
+"""Telemetry services."""
+

backend/app/telemetry/service.py

@@ -0,0 +1,78 @@
+from __future__ import annotations
+
+from collections import deque
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from time import monotonic
+
+import psutil
+
+from app.dmx.backends import BackendStatus
+
+
+@dataclass(slots=True)
+class TelemetryEvent:
+    created_at: datetime
+    category: str
+    level: str
+    message: str
+
+
+class TelemetryService:
+    def __init__(self) -> None:
+        self.started_at = monotonic()
+        self.events: deque[TelemetryEvent] = deque(maxlen=1000)
+        self.last_sent_at: datetime | None = None
+        self.last_error: str | None = None
+        self.reconnect_count = 0
+        self.frames_sent = 0
+        self.send_errors = 0
+
+    def record_send_success(self, status: BackendStatus) -> None:
+        self.last_sent_at = datetime.now(UTC)
+        self.last_error = None
+        self.reconnect_count = status.reconnect_count
+        self.frames_sent = status.frames_sent
+        self.send_errors = status.send_errors
+
+    def record_send_failure(self, error: str, status: BackendStatus) -> None:
+        self.last_error = error
+        self.reconnect_count = status.reconnect_count
+        self.frames_sent = status.frames_sent
+        self.send_errors = status.send_errors
+        self.events.append(
+            TelemetryEvent(datetime.now(UTC), "DMX", "ERROR", error)
+        )
+
+    def snapshot(self, queue_depth: int = 0) -> dict[str, object]:
+        temperature = None
+        try:
+            readings = psutil.sensors_temperatures()
+            if readings:
+                first = next(iter(readings.values()))
+                if first:
+                    temperature = float(first[0].current)
+        except Exception:
+            temperature = None
+
+        return {
+            "uptime_seconds": round(monotonic() - self.started_at, 2),
+            "cpu_percent": psutil.cpu_percent(interval=None),
+            "ram_percent": psutil.virtual_memory().percent,
+            "temperature_c": temperature,
+            "queue_depth": queue_depth,
+            "reconnect_count": self.reconnect_count,
+            "last_error": self.last_error,
+            "last_sent_at": self.last_sent_at,
+            "frames_sent": self.frames_sent,
+            "send_errors": self.send_errors,
+            "events": [
+                {
+                    "created_at": event.created_at.isoformat(),
+                    "category": event.category,
+                    "level": event.level,
+                    "message": event.message,
+                }
+                for event in list(self.events)[-50:]
+            ],
+        }