feat: make each plugin an npm workspace built by a termix-plugin CLI

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

@@ -0,0 +1,80 @@
+import type { Client, ConnectConfig } from "ssh2";
+import { statsLogger } from "../../../../src/backend/utils/logger.js";
+
+export interface MetricsSession {
+  client: Client;
+  isConnected: boolean;
+  lastActive: number;
+  timeout?: NodeJS.Timeout;
+  activeOperations: number;
+  hostId: number;
+  userId: string;
+}
+
+export interface PendingTOTPSession {
+  client: Client;
+  finish: (responses: string[]) => void;
+  config: ConnectConfig;
+  createdAt: number;
+  sessionId: string;
+  hostId: number;
+  userId: string;
+  prompts?: Array<{ prompt: string; echo: boolean }>;
+  totpPromptIndex?: number;
+  resolvedPassword?: string;
+  totpAttempts: number;
+}
+
+export interface MetricsViewer {
+  sessionId: string;
+  userId: string;
+  hostId: number;
+  lastHeartbeat: number;
+}
+
+export const metricsSessions: Record<string, MetricsSession> = {};
+export const pendingTOTPSessions: Record<string, PendingTOTPSession> = {};
+
+export function cleanupMetricsSession(sessionId: string): void {
+  const session = metricsSessions[sessionId];
+  if (session) {
+    if (session.activeOperations > 0) {
+      statsLogger.warn(
+        `Deferring metrics session cleanup - ${session.activeOperations} active operations`,
+        {
+          operation: "cleanup_deferred",
+          sessionId,
+          activeOperations: session.activeOperations,
+        },
+      );
+      scheduleMetricsSessionCleanup(sessionId);
+      return;
+    }
+
+    try {
+      session.client.end();
+    } catch {
+      // expected
+    }
+    clearTimeout(session.timeout);
+    delete metricsSessions[sessionId];
+  }
+}
+
+export function scheduleMetricsSessionCleanup(sessionId: string): void {
+  const session = metricsSessions[sessionId];
+  if (session) {
+    if (session.timeout) clearTimeout(session.timeout);
+
+    session.timeout = setTimeout(
+      () => {
+        cleanupMetricsSession(sessionId);
+      },
+      30 * 60 * 1000,
+    );
+  }
+}
+
+export function getSessionKey(hostId: number, userId: string): string {
+  return `${userId}:${hostId}`;
+}