Add MCP servers and custom tools for bots

Two new settings pages, MCPs and Tools. Super admins define them; super
admins and admins attach them to bots, to workspaces (every bot there),
or to every bot. Bots get them in chat replies and tasks.

- Custom tools: a JSON-schema of arguments plus an HTTP request, a script
  on the bot's computer, or a prompt, templated with {{args.x}} and
  {{env.KEY}}, secrets redacted from results.
- MCP servers: remote (URL and headers) or stdio commands run on the host
  with a setup command and an isolated env, in a per-process pool. Tools
  are listed into a cache and connect on first call.
- Add, edit, access and try open in modals.
- Markdown, JSON and command fields use twui's AceEditor (CodeEditor),
  its scripts loaded on demand.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/harness/mcp/open-mcp-server.ts

@@ -0,0 +1,48 @@
+import type { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import type { McpServerRecord } from "@/src/types";
+import fillTemplate from "@/src/utils/fill-template";
+import connectMcpServer from "./connect-mcp-server";
+import grabStdioMcpClient from "./mcp-stdio-pool";
+
+type Params = {
+    server: McpServerRecord;
+    /**
+     * What its templates (`{{env.KEY}}`) read.
+     */
+    envs: { key: string; value: string }[];
+    signal?: AbortSignal;
+};
+
+/**
+ * How one run reaches an MCP server, without connecting yet: `client()`
+ * connects on the first call and is reused after. A remote server gets
+ * its own connection for the run (closed by `close`); a stdio server is
+ * shared through the process's pool and keeps running.
+ */
+export default function openMcpServer({ server, envs, signal }: Params) {
+    let remote: Promise<Client> | undefined;
+
+    const client = () => {
+        if (server.transport == "stdio") return grabStdioMcpClient({ server, envs });
+
+        remote ||= connectMcpServer({
+            url: fillTemplate({ template: server.url, envs }),
+            headers: Object.fromEntries(
+                Object.entries(server.headers).map(([key, value]) => [key, fillTemplate({ template: value, envs })]),
+            ),
+            signal,
+        }).catch((error) => {
+            remote = undefined;
+            throw error;
+        });
+
+        return remote;
+    };
+
+    const close = async () => {
+        if (!remote) return;
+        await (await remote.catch(() => null))?.close().catch(() => {});
+    };
+
+    return { client, close };
+}