feat: finish the host-metrics plugin, move host status into core (B16)

plugins/host-metrics/src/backend/collectors.ts

@@ -0,0 +1,48 @@
+import type { Client } from "ssh2";
+import type { PluginServices } from "@termix/plugin-sdk/backend";
+import type { MetricsLogger } from "./log.js";
+
+export const COLLECTORS_SERVICE = "host-metrics.collectors";
+
+/**
+ * The "host-metrics.collectors" service, version 1. Another plugin provides
+ * it under its own provider name (manifest `provides[].names`) to add data
+ * to every sample. It runs on the sample's SSH connection, as the host's
+ * owner, and its result lands in the snapshot under `extra[<name>]`. A
+ * collector that throws is skipped for that sample.
+ */
+export interface MetricsCollectorV1 {
+  collect: (client: Client, hostId: number) => Promise<unknown>;
+}
+
+export class CollectorRegistry {
+  constructor(
+    private readonly services: PluginServices,
+    private readonly log: MetricsLogger,
+  ) {}
+
+  async run(
+    client: Client,
+    hostId: number,
+    ownerUserId: string,
+  ): Promise<Record<string, unknown>> {
+    const results: Record<string, unknown> = {};
+    for (const provider of this.services.providers(COLLECTORS_SERVICE)) {
+      if (!provider) continue;
+      try {
+        const collector = this.services.get<Partial<MetricsCollectorV1>>(
+          COLLECTORS_SERVICE,
+          { provider, userId: ownerUserId },
+        );
+        if (typeof collector.collect !== "function") continue;
+        results[provider] = await collector.collect(client, hostId);
+      } catch (error) {
+        this.log.debug(`Metrics collector ${provider} failed`, {
+          hostId,
+          error: error instanceof Error ? error.message : String(error),
+        });
+      }
+    }
+    return results;
+  }
+}