feat: add combineSeries for GPU combination aggregation

tests/metrics-poller.test.ts

@@ -2,7 +2,7 @@ import assert from "node:assert/strict";
 import { readFileSync } from "node:fs";
 import { test } from "node:test";
 import { type LlamaSwapConfig } from "../src/lib/util";
-import { MetricsPoller } from "../src/lib/metrics-poller";
+import { combineSeries, MetricsPoller } from "../src/lib/metrics-poller";
 
 
 const FIXTURE = readFileSync(new URL("./fixtures/metrics.txt", import.meta.url), "utf8");
@@ -61,3 +61,31 @@ test("poller reports offline after a fetch failure and recovers", async () => {
   assert.equal(poller.isOffline(), false);
   assert.ok(poller.getValue("0", "util_percent") !== undefined);
 });
+
+test("combineSeries averages util and sums power", () => {
+  const util = combineSeries(
+    [
+      [10, 20, 30],
+      [20, 40, 60],
+    ],
+    "util_percent",
+  );
+  assert.deepEqual(util, { value: 45, history: [15, 30, 45] });
+
+  const power = combineSeries(
+    [
+      [100, 200],
+      [150, 250],
+    ],
+    "power",
+  );
+  assert.deepEqual(power, { value: 450, history: [250, 450] });
+});
+
+test("combineSeries takes the max temperature and skips gaps", () => {
+  const temp = combineSeries([[50, 70], [60]], "temperature");
+  assert.deepEqual(temp, { value: 70, history: [60, 70] });
+
+  const empty = combineSeries([[], []], "temperature");
+  assert.deepEqual(empty, { value: undefined, history: [] });
+});