fix: stabilize cloud computer use mcp

electron/computerAgent.js

@@ -3,6 +3,7 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 
 const IPC_PREFIX = '@@CUAGENT@@';
+const TARGET_STATUS_TIMEOUT_MS = 5000;
 
 function getDesktopPath() {
   const currentPath = process.env.PATH || '';
@@ -35,6 +36,38 @@ function toAgentWsUrl(httpUrl) {
   }
 }
 
+async function isComputerUseEnabledTarget(httpUrl, apiKey) {
+  let statusUrl;
+  try {
+    statusUrl = new URL('/api/computer-use/status', httpUrl).toString();
+  } catch {
+    return false;
+  }
+
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), TARGET_STATUS_TIMEOUT_MS);
+  try {
+    const response = await fetch(statusUrl, {
+      signal: controller.signal,
+      headers: apiKey ? { 'X-API-Key': apiKey } : undefined,
+    });
+    const body = await response.json().catch(() => null);
+    return response.ok && body?.success !== false && body?.data?.enabled === true;
+  } catch {
+    return false;
+  } finally {
+    clearTimeout(timeout);
+  }
+}
+
+async function filterEnabledComputerUseTargets(targets, apiKey) {
+  const checks = await Promise.all(targets.map(async (target) => ({
+    target,
+    enabled: await isComputerUseEnabledTarget(target, apiKey),
+  })));
+  return checks.filter((item) => item.enabled).map((item) => item.target);
+}
+
 /**
  * Keeps a Computer Use desktop agent connected to running cloud environments
  * while desktop access is enabled.
@@ -102,7 +135,8 @@ export class ComputerAgentController {
 
   async sync() {
     const targets = this.settings.enabled ? (this.getRunningEnvironmentUrls?.() || []) : [];
-    const wsTargets = targets.map(toAgentWsUrl).filter(Boolean);
+    const enabledTargets = this.settings.enabled ? await filterEnabledComputerUseTargets(targets, this.getApiKey?.() || '') : [];
+    const wsTargets = enabledTargets.map(toAgentWsUrl).filter(Boolean);
 
     const sameTargets =
       wsTargets.length === this.currentTargets.length &&
@@ -209,6 +243,12 @@ export class ComputerAgentController {
         this.connectedUrls.delete(payload.url);
         this.lastEvent = 'disconnected';
         this.onChange?.();
+        if (payload.reason && /computer use.*disabled/i.test(payload.reason)) {
+          void this.sync().catch((error) => {
+            this.lastError = error instanceof Error ? error.message : 'Failed to sync Computer Use targets.';
+            this.onChange?.();
+          });
+        }
         break;
       case 'starting':
         this.lastEvent = 'starting';

server/computer-use-agent.ts

@@ -245,8 +245,12 @@ function connect(url: string): void {
       }
     });
 
-    const scheduleReconnect = () => {
-      emitToParent({ type: 'disconnected', url });
+    const scheduleReconnect = (code?: number, reason?: Buffer) => {
+      const reasonText = reason?.toString() || '';
+      emitToParent({ type: 'disconnected', url, code, reason: reasonText });
+      if (code === 1008 && /computer use.*disabled/i.test(reasonText)) {
+        return;
+      }
       setTimeout(open, reconnectMs);
       reconnectMs = Math.min(reconnectMs * 2, RECONNECT_MAX_MS);
     };

server/computer-use-mcp.ts

@@ -470,19 +470,25 @@ async function handleMessage(message: JsonRpcRequest) {
   throw new Error(`Unsupported method: ${message.method}`);
 }
 
-function writeMessage(message: Record<string, unknown>) {
+type MessageFraming = 'content-length' | 'line';
+
+function writeMessage(message: Record<string, unknown>, framing: MessageFraming) {
   const payload = JSON.stringify(message);
+  if (framing === 'line') {
+    process.stdout.write(`${payload}\n`);
+    return;
+  }
   process.stdout.write(`Content-Length: ${Buffer.byteLength(payload, 'utf8')}\r\n\r\n${payload}`);
 }
 
-function sendResult(id: string | number | null | undefined, result: unknown) {
+function sendResult(id: string | number | null | undefined, result: unknown, framing: MessageFraming) {
   if (id === undefined) {
     return;
   }
-  writeMessage({ jsonrpc: '2.0', id, result });
+  writeMessage({ jsonrpc: '2.0', id, result }, framing);
 }
 
-function sendError(id: string | number | null | undefined, error: unknown) {
+function sendError(id: string | number | null | undefined, error: unknown, framing: MessageFraming) {
   if (id === undefined) {
     return;
   }
@@ -493,28 +499,69 @@ function sendError(id: string | number | null | undefined, error: unknown) {
       code: -32000,
       message: error instanceof Error ? error.message : String(error),
     },
-  });
+  }, framing);
 }
 
 let buffer = Buffer.alloc(0);
 
+function handleRawMessage(rawMessage: string, framing: MessageFraming) {
+  void (async () => {
+    let request: JsonRpcRequest | null = null;
+    try {
+      request = JSON.parse(rawMessage) as JsonRpcRequest;
+      const result = await handleMessage(request);
+      sendResult(request.id, result, framing);
+    } catch (error) {
+      sendError(request?.id ?? null, error, framing);
+    }
+  })();
+}
+
+function findHeaderEnd(input: Buffer): { index: number; length: number } | null {
+  const crlf = input.indexOf('\r\n\r\n');
+  if (crlf !== -1) {
+    return { index: crlf, length: 4 };
+  }
+  const lf = input.indexOf('\n\n');
+  if (lf !== -1) {
+    return { index: lf, length: 2 };
+  }
+  return null;
+}
+
 process.stdin.on('data', (chunk) => {
   buffer = Buffer.concat([buffer, chunk]);
   while (true) {
-    const headerEnd = buffer.indexOf('\r\n\r\n');
-    if (headerEnd === -1) {
-      return;
+    const headerEnd = findHeaderEnd(buffer);
+    if (!headerEnd) {
+      if (/^Content-Length:/i.test(buffer.toString('utf8', 0, Math.min(buffer.length, 32)))) {
+        return;
+      }
+
+      const newline = buffer.indexOf('\n');
+      if (newline === -1) {
+        return;
+      }
+
+      const rawLine = buffer.slice(0, newline).toString('utf8').trim();
+      buffer = buffer.slice(newline + 1);
+      if (!rawLine) {
+        continue;
+      }
+
+      handleRawMessage(rawLine, 'line');
+      continue;
     }
 
-    const header = buffer.slice(0, headerEnd).toString('utf8');
+    const header = buffer.slice(0, headerEnd.index).toString('utf8');
     const lengthMatch = /Content-Length:\s*(\d+)/i.exec(header);
     if (!lengthMatch) {
-      buffer = buffer.slice(headerEnd + 4);
+      buffer = buffer.slice(headerEnd.index + headerEnd.length);
       continue;
     }
 
     const length = Number.parseInt(lengthMatch[1], 10);
-    const messageStart = headerEnd + 4;
+    const messageStart = headerEnd.index + headerEnd.length;
     const messageEnd = messageStart + length;
     if (buffer.length < messageEnd) {
       return;
@@ -522,16 +569,6 @@ process.stdin.on('data', (chunk) => {
 
     const rawMessage = buffer.slice(messageStart, messageEnd).toString('utf8');
     buffer = buffer.slice(messageEnd);
-
-    void (async () => {
-      let request: JsonRpcRequest | null = null;
-      try {
-        request = JSON.parse(rawMessage) as JsonRpcRequest;
-        const result = await handleMessage(request);
-        sendResult(request.id, result);
-      } catch (error) {
-        sendError(request?.id ?? null, error);
-      }
-    })();
+    handleRawMessage(rawMessage, 'content-length');
   }
 });

server/load-env.js

@@ -22,7 +22,7 @@ try {
     }
   });
 } catch (e) {
-  console.log('No .env file found or error reading it:', e.message);
+  console.error('No .env file found or error reading it:', e.message);
 }
 
 // Keep the default database in a stable user-level location so rebuilding dist-server

server/modules/computer-use/computer-use.service.ts

@@ -465,6 +465,7 @@ export const computerUseService = {
       await this.registerAgentMcp();
     } else {
       await this.unregisterAgentMcp();
+      desktopAgentRelay.disconnectAll('Computer Use was disabled in this environment.');
       stopSessions('settings:disabled', 'Computer Use was disabled in settings.');
     }
     return next;
@@ -909,6 +910,7 @@ export const computerUseService = {
 
 // Drive cloud MCP exposure + session teardown off desktop-agent connectivity.
 desktopAgentRelay.setHooks({
+  canAcceptConnection: () => getRuntime() === 'cloud' && readSettings().enabled,
   onFirstConnect: () => computerUseService.onDesktopAgentConnected(),
   onLastDisconnect: () => computerUseService.onDesktopAgentDisconnected(),
 });

server/modules/computer-use/desktop-agent-relay.service.ts

@@ -18,6 +18,7 @@ type ConnectedAgent = {
 };
 
 type RelayLifecycleHooks = {
+  canAcceptConnection?: () => boolean;
   onFirstConnect?: () => void | Promise<void>;
   onLastDisconnect?: () => void | Promise<void>;
 };
@@ -54,15 +55,25 @@ export const desktopAgentRelay = {
     hooks = next;
   },
 
-  register(ws: WebSocket, label = 'desktop-agent'): void {
+  register(ws: WebSocket, label = 'desktop-agent'): boolean {
+    if (hooks.canAcceptConnection && !hooks.canAcceptConnection()) {
+      console.log(`[DesktopAgent] Rejected (${label}); Computer Use is disabled.`);
+      try {
+        ws.close(1008, 'Computer Use is disabled in this environment.');
+      } catch {
+        // ignore close failures
+      }
+      return false;
+    }
+
     const wasEmpty = pickAgent() === undefined;
     agents.set(ws, { ws, label, registeredAt: new Date().toISOString() });
     console.log(`[DesktopAgent] Registered (${label}); ${agents.size} connected.`);
 
     ws.on('close', () => {
-      agents.delete(ws);
+      const wasRegistered = agents.delete(ws);
       console.log(`[DesktopAgent] Disconnected (${label}); ${agents.size} remain.`);
-      if (pickAgent() === undefined) {
+      if (wasRegistered && pickAgent() === undefined) {
         rejectAllPending('Desktop agent disconnected.');
         void hooks.onLastDisconnect?.();
       }
@@ -71,6 +82,24 @@ export const desktopAgentRelay = {
     if (wasEmpty) {
       void hooks.onFirstConnect?.();
     }
+    return true;
+  },
+
+  disconnectAll(reason = 'Desktop agent disconnected.'): void {
+    const hadAgent = pickAgent() !== undefined;
+    const sockets = [...agents.keys()];
+    agents.clear();
+    for (const ws of sockets) {
+      try {
+        ws.close(1008, reason);
+      } catch {
+        // ignore close failures
+      }
+    }
+    rejectAllPending(reason);
+    if (hadAgent) {
+      void hooks.onLastDisconnect?.();
+    }
   },
 
   /** Resolves a pending relay call with the desktop agent's reply. */

src/components/settings/view/tabs/computer-use-settings/ComputerUseSettingsTab.tsx

@@ -102,6 +102,7 @@ export default function ComputerUseSettingsTab() {
 
   const isCloud = status?.runtime === 'cloud';
   const effectiveEnabled = isCloud ? status?.enabled === true : settings.enabled;
+  const showCloudDesktopAccess = Boolean(isCloud && effectiveEnabled);
   const needsRuntime = Boolean(effectiveEnabled && !isCloud && status && (!status.nutInstalled || !status.screenshotInstalled));
   const desktopAgentCount = status?.desktopAgentCount ?? (status?.desktopAgentConnected ? 1 : 0);
   const modeDescription = isCloud
@@ -144,7 +145,7 @@ export default function ComputerUseSettingsTab() {
             />
           </SettingsRow>
 
-          {isCloud && (
+          {showCloudDesktopAccess && (
             <SettingsRow
               label="Cloud desktop access"
               description={status?.desktopAgentConnected
@@ -176,9 +177,9 @@ export default function ComputerUseSettingsTab() {
             </SettingsRow>
           )}
 
-          {(needsRuntime || isCloud || error) && (
+          {(needsRuntime || showCloudDesktopAccess || error) && (
             <div className="space-y-4 px-4 py-4">
-              {isCloud && !status?.desktopAgentConnected && (
+              {showCloudDesktopAccess && !status?.desktopAgentConnected && (
                 <div className="rounded-md border border-border bg-muted/40 px-3 py-3 text-sm text-muted-foreground">
                   <div className="font-medium text-foreground">To link this computer</div>
                   <ol className="mt-2 list-decimal space-y-1 pl-5">
@@ -190,7 +191,7 @@ export default function ComputerUseSettingsTab() {
                 </div>
               )}
 
-              {isCloud && status?.desktopAgentConnected && (
+              {showCloudDesktopAccess && status?.desktopAgentConnected && (
                 <div className="rounded-md border border-border bg-muted/40 px-3 py-2 text-sm text-muted-foreground">
                   {desktopAgentCount > 1
                     ? `${desktopAgentCount} desktops are linked. Agents will use one available desktop; stop Computer Use on any desktop you do not want agents to control.`