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

plugins/host-metrics/src/backend/managers/route-helpers.ts

@@ -0,0 +1,62 @@
+import { getErrorMessage } from "../../../../../src/backend/utils/error-message.js";
+import type { Request, Response } from "express";
+import type { Client } from "ssh2";
+import type { AuthenticatedRequest } from "../../../../../src/types/index.js";
+import { statsLogger } from "../../../../../src/backend/utils/logger.js";
+import { ElevationError } from "../../../../../src/backend/hosts/metrics-shared/exec-elevated.js";
+import type { ManagerHost, RunOnHost } from "./types.js";
+import type { HostAction } from "../../../../../src/backend/utils/permission-manager.js";
+
+export class AccessDeniedError extends Error {
+  constructor(message = "No access to this host") {
+    super(message);
+    this.name = "AccessDeniedError";
+  }
+}
+
+export class ManagerInputError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "ManagerInputError";
+  }
+}
+
+/**
+ * Wrap a manager handler: parses hostId, runs `fn` on a pooled connection at the
+ * given access level, and maps known errors to clean HTTP responses.
+ */
+export function managerHandler(
+  runOnHost: RunOnHost,
+  level: HostAction,
+  operation: string,
+  fn: (client: Client, host: ManagerHost, req: Request) => Promise<unknown>,
+) {
+  return async (req: Request, res: Response) => {
+    const userId = (req as AuthenticatedRequest).userId;
+    const hostId = parseInt(String(req.params.id), 10);
+    try {
+      const result = await runOnHost(hostId, userId, level, (client, host) =>
+        fn(client, host, req),
+      );
+      return res.json(result);
+    } catch (error) {
+      if (error instanceof ManagerInputError) {
+        return res.status(400).json({ error: error.message });
+      }
+      if (error instanceof AccessDeniedError) {
+        return res.status(403).json({ error: error.message });
+      }
+      if (error instanceof ElevationError) {
+        return res.status(403).json({ error: error.message, code: error.code });
+      }
+      statsLogger.error(`Manager operation failed: ${operation}`, {
+        operation,
+        hostId,
+        error: error instanceof Error ? error.message : String(error),
+      });
+      return res.status(500).json({
+        error: getErrorMessage(error, "Operation failed"),
+      });
+    }
+  };
+}