fix(examples/client-multi-server): try/finally cleanup, assertive route lookups, exitCode pattern

Address two Claude bot review concerns posted after the prior approval
(2026-04-09 17:21:58):

1. Cleanup pattern: main() body had no try/finally, so the cleanup loop
   never ran when an error propagated to the .catch() handler that called
   process.exit(1) synchronously. Wrapped main() body in try/finally;
   moved cleanup loop into finally; replaced process.exit(1) with
   process.exitCode = 1 so the finally block actually runs on error.

2. Silent routing failures: hardcoded prefixed keys with if-guards meant
   a missing key (renamed server, renamed tool) printed only the routing
   demo header then "All servers disconnected." with zero indication that
   no routing was demonstrated. Replaced silent if-guards with assertive
   lookups that throw a clear error identifying the missing key.

Renamed result/text variables to alertsResult/alertsText/weatherResult/
weatherText since de-indenting the call blocks would put two const result
declarations in the same scope. No semantic change to the demo output.

Local typecheck:all, lint:all, and build:all all pass.

Co-Authored-By: Tadao <tadao@travisfixes.com>

Author: travisbreaks

examples/client-multi-server/src/index.ts

@@ -36,77 +36,81 @@ const toolRouter = new Map<
 async function main() {
   const clients: Client[] = [];
 
-  // 1. Connect to each server and discover tools
-  for (const { name, script } of servers) {
-    const transport = new StdioClientTransport({
-      command: process.execPath,
-      args: ['--import', 'tsx', script],
-    });
-    const client = new Client({ name: `router-${name}`, version: '1.0.0' });
-    await client.connect(transport);
-    clients.push(client);
-
-    const { tools } = await client.listTools();
-    for (const tool of tools) {
-      const prefixed = `${name}__${tool.name}`;
-      toolRouter.set(prefixed, {
-        client,
-        originalName: tool.name,
-        serverName: name,
+  try {
+    // 1. Connect to each server and discover tools
+    for (const { name, script } of servers) {
+      const transport = new StdioClientTransport({
+        command: process.execPath,
+        args: ['--import', 'tsx', script],
       });
-    }
+      const client = new Client({ name: `router-${name}`, version: '1.0.0' });
+      await client.connect(transport);
+      clients.push(client);
 
-    console.log(`[${name}] connected, tools: ${tools.map((t) => t.name).join(', ')}`);
-  }
+      const { tools } = await client.listTools();
+      for (const tool of tools) {
+        const prefixed = `${name}__${tool.name}`;
+        toolRouter.set(prefixed, {
+          client,
+          originalName: tool.name,
+          serverName: name,
+        });
+      }
 
-  console.log(`\nRouting table (${toolRouter.size} tools):`);
-  for (const [prefixed, { serverName, originalName }] of toolRouter) {
-    console.log(`  ${prefixed} -> ${serverName} (${originalName})`);
-  }
+      console.log(`[${name}] connected, tools: ${tools.map((t) => t.name).join(', ')}`);
+    }
+
+    console.log(`\nRouting table (${toolRouter.size} tools):`);
+    for (const [prefixed, { serverName, originalName }] of toolRouter) {
+      console.log(`  ${prefixed} -> ${serverName} (${originalName})`);
+    }
 
-  // 2. Demonstrate routing: call one tool from each server
-  console.log('\n--- Routing demo ---\n');
+    // 2. Demonstrate routing: call one tool from each server
+    console.log('\n--- Routing demo ---\n');
 
-  // Call get-alerts from weather-nws (server-quickstart)
-  const alertsKey = 'weather-nws__get-alerts';
-  const alertsRoute = toolRouter.get(alertsKey);
-  if (alertsRoute) {
+    // Call get-alerts from weather-nws (server-quickstart)
+    const alertsKey = 'weather-nws__get-alerts';
+    const alertsRoute = toolRouter.get(alertsKey);
+    if (!alertsRoute) {
+      throw new Error(`Routing demo: no route for ${alertsKey}. Did a server name or tool name change?`);
+    }
     console.log(`Calling ${alertsKey} ...`);
-    const result = await alertsRoute.client.callTool({
+    const alertsResult = await alertsRoute.client.callTool({
       name: alertsRoute.originalName,
       arguments: { state: 'CA' },
     });
-    const text = result.content
+    const alertsText = alertsResult.content
       .filter((c) => c.type === 'text')
       .map((c) => c.text)
       .join('\n');
-    console.log(`Result: ${text.slice(0, 200)}...\n`);
-  }
+    console.log(`Result: ${alertsText.slice(0, 200)}...\n`);
 
-  // Call get_weather from weather-structured (mcpServerOutputSchema)
-  const weatherKey = 'weather-structured__get_weather';
-  const weatherRoute = toolRouter.get(weatherKey);
-  if (weatherRoute) {
+    // Call get_weather from weather-structured (mcpServerOutputSchema)
+    const weatherKey = 'weather-structured__get_weather';
+    const weatherRoute = toolRouter.get(weatherKey);
+    if (!weatherRoute) {
+      throw new Error(`Routing demo: no route for ${weatherKey}. Did a server name or tool name change?`);
+    }
     console.log(`Calling ${weatherKey} ...`);
-    const result = await weatherRoute.client.callTool({
+    const weatherResult = await weatherRoute.client.callTool({
       name: weatherRoute.originalName,
       arguments: { city: 'Seattle', country: 'US' },
     });
-    const text = result.content
+    const weatherText = weatherResult.content
       .filter((c) => c.type === 'text')
       .map((c) => c.text)
       .join('\n');
-    console.log(`Result: ${text.slice(0, 200)}...\n`);
-  }
-
-  // 3. Cleanup
-  for (const client of clients) {
-    await client.close();
+    console.log(`Result: ${weatherText.slice(0, 200)}...\n`);
+  } finally {
+    // 3. Cleanup runs on success and error
+    for (const client of clients) {
+      await client.close();
+    }
+    console.log('All servers disconnected.');
   }
-  console.log('All servers disconnected.');
 }
 
 main().catch((err) => {
   console.error('Fatal error:', err);
-  process.exit(1);
+  process.exitCode = 1;
 });