feat: ship host metrics as a first-party in-process plugin

plugins/host-metrics/frontend/cards/gpu-history.ts

@@ -0,0 +1,31 @@
+import type { GpuDevice } from "@/types/stats-widgets";
+
+export interface GpuHistory {
+  utilization: number[];
+  memory: number[];
+}
+
+/** Live sparkline series keyed by GPU index. */
+export type GpuHistories = Record<number, GpuHistory>;
+
+/**
+ * Appends one poll's readings to each GPU's series. GPUs missing from the poll
+ * lose their series so a re-enumerated device never inherits stale samples.
+ */
+export function appendGpuHistories(
+  prev: GpuHistories,
+  gpus: GpuDevice[] | undefined,
+  maxLength: number,
+): GpuHistories {
+  const add = (arr: number[] | undefined, v: number | null) =>
+    [...(arr ?? []), v ?? 0].slice(-maxLength);
+
+  const next: GpuHistories = {};
+  for (const gpu of gpus ?? []) {
+    next[gpu.index] = {
+      utilization: add(prev[gpu.index]?.utilization, gpu.utilizationPercent),
+      memory: add(prev[gpu.index]?.memory, gpu.memoryPercent),
+    };
+  }
+  return next;
+}