chore(vendor): import pi 0.85.1

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/agent/benchmark/session/loaded-footprint-worker.ts

@@ -0,0 +1,34 @@
+import {
+	STORAGE_BENCHMARK_DATASETS,
+	seedStorageBenchmark,
+} from "../../src/harness/session/testing/index.ts";
+import { storageBenchmarkTargets } from "./storage-targets.ts";
+
+function collectGarbage(): void {
+	if (globalThis.gc === undefined) throw new Error("Loaded footprint measurement requires Node.js --expose-gc");
+	for (let index = 0; index < 3; index++) globalThis.gc();
+}
+
+const [targetName, datasetName] = process.argv.slice(2);
+const target = storageBenchmarkTargets.find((candidate) => candidate.name === targetName);
+if (target === undefined) throw new Error(`Unknown storage benchmark target: ${targetName}`);
+const dataset = STORAGE_BENCHMARK_DATASETS.find((candidate) => candidate.name === datasetName);
+if (dataset === undefined) throw new Error(`Unknown storage benchmark dataset: ${datasetName}`);
+
+await using fixture = await target.createFixture();
+collectGarbage();
+const before = process.memoryUsage();
+await seedStorageBenchmark(fixture.storage, dataset);
+collectGarbage();
+const after = process.memoryUsage();
+
+console.log(
+	JSON.stringify({
+		target: target.name,
+		dataset: dataset.name,
+		entryCount: dataset.entryCount,
+		heapUsedBytes: after.heapUsed - before.heapUsed,
+		rssBytes: after.rss - before.rss,
+		externalBytes: after.external - before.external,
+	}),
+);