diff --git a/src/mcp/bridge.ts b/src/mcp/bridge.ts
index a716a7b..cd34889 100644
--- a/src/mcp/bridge.ts
+++ b/src/mcp/bridge.ts
@@ -124,31 +124,48 @@ export async function resolveLocalInputs(
   return args;
 }
 
-/** The hosted device tools, connected lazily and remade when auth changes. */
+/**
+ * The hosted device tools, over one connection made on first use and shared
+ * by every call.
+ *
+ * Auth goes on each request, not on the connection. Remaking the connection
+ * when a session is renewed would close it under calls still running (a `run`
+ * can take minutes), and they would fail with "Connection closed" while the
+ * flow carried on. The hosted /mcp is stateless, so nothing ties the
+ * connection to the auth it started with.
+ */
 class RemoteDevices {
-  private client: Client | null = null;
-  private auth: AuthContext | null = null;
+  private connecting: Promise<Client> | null = null;
   private tools: Tool[] | null = null;
 
-  async connect(): Promise<{ client: Client; ctx: { apiUrl: string; auth: AuthContext } }> {
-    const ctx = await getContext();
-    if (this.client && this.auth === ctx.auth) return { client: this.client, ctx };
+  /** Calls that arrive together share one connect. A failed one is retried by the next call. */
+  connect(): Promise<Client> {
+    this.connecting ??= this.open().catch((error: unknown) => {
+      this.connecting = null;
+      throw error;
+    });
+    return this.connecting;
+  }
 
-    await this.client?.close().catch(() => {});
+  private async open(): Promise<Client> {
+    const { apiUrl } = await getContext();
     const client = new Client({ name: 'dcd-mcp-bridge', version: getCliVersion() });
     await client.connect(
-      new StreamableHTTPClientTransport(new URL(`${ctx.apiUrl}/mcp`), {
-        requestInit: { headers: { ...ctx.auth.headers } },
+      new StreamableHTTPClientTransport(new URL(`${apiUrl}/mcp`), {
+        fetch: async (url, init) => {
+          const { auth } = await getContext();
+          const headers = new Headers(init?.headers);
+          for (const [key, value] of Object.entries(auth.headers)) headers.set(key, value);
+          return fetch(url, { ...init, headers });
+        },
       }),
     );
-    this.client = client;
-    this.auth = ctx.auth;
-    return { client, ctx };
+    return client;
   }
 
   async list(): Promise<Tool[]> {
     if (this.tools) return this.tools;
-    const { client } = await this.connect();
+    const client = await this.connect();
     const { tools } = await client.listTools();
     this.tools = tools;
     return tools;
@@ -224,8 +241,8 @@ export async function createBridgeServer(
       if (readOnly && !remote.isReadOnly(name)) {
         return errorResult(`${name} is not available in read-only mode.`);
       }
-      const { client, ctx } = await remote.connect();
-      const remoteArgs = await resolveLocalInputs(name, args, ctx);
+      const client = await remote.connect();
+      const remoteArgs = await resolveLocalInputs(name, args, await getContext());
       return (await client.callTool({ name, arguments: remoteArgs }, undefined, options)) as CallToolResult;
     });
   });
diff --git a/src/utils/browser.ts b/src/utils/browser.ts
index e196034..627cae9 100644
--- a/src/utils/browser.ts
+++ b/src/utils/browser.ts
@@ -1,13 +1,30 @@
 import { spawn } from 'node:child_process';
 
-/** Open `url` in the default browser. False if no opener could be started. */
+/**
+ * Open `url` in the default browser. False if it isn't an http(s) URL or no
+ * opener could be started.
+ *
+ * Only http(s) is opened, so a URL can't name a local file or start with `-`
+ * and be read as an option. No opener goes through a shell: Windows uses
+ * rundll32, because `cmd /c start` parses the URL again and treats its `&`
+ * as a command separator.
+ */
 export function openBrowser(url: string): boolean {
+  let href: string;
+  try {
+    const parsed = new URL(url);
+    if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') return false;
+    href = parsed.href;
+  } catch {
+    return false;
+  }
+
   const cmd =
     process.platform === 'darwin'
-      ? { bin: 'open', args: [url] }
+      ? { bin: 'open', args: [href] }
       : process.platform === 'win32'
-        ? { bin: 'cmd', args: ['/c', 'start', '""', url] }
-        : { bin: 'xdg-open', args: [url] };
+        ? { bin: 'rundll32', args: ['url.dll,FileProtocolHandler', href] }
+        : { bin: 'xdg-open', args: [href] };
   try {
     const child = spawn(cmd.bin, cmd.args, { detached: true, stdio: 'ignore' });
     child.unref();
diff --git a/test/unit/browser.test.ts b/test/unit/browser.test.ts
new file mode 100644
index 0000000..0934735
--- /dev/null
+++ b/test/unit/browser.test.ts
@@ -0,0 +1,11 @@
+import { expect } from 'chai';
+
+import { openBrowser } from '../../src/utils/browser.js';
+
+describe('openBrowser', () => {
+  it('opens nothing that is not an http(s) URL', () => {
+    expect(openBrowser('file:///etc/passwd')).to.equal(false);
+    expect(openBrowser('--help')).to.equal(false);
+    expect(openBrowser('not a url')).to.equal(false);
+  });
+});
diff --git a/test/unit/mcp-bridge.test.ts b/test/unit/mcp-bridge.test.ts
index 32e2d2a..622cdbd 100644
--- a/test/unit/mcp-bridge.test.ts
+++ b/test/unit/mcp-bridge.test.ts
@@ -18,8 +18,14 @@ import { clearContextCache } from '../../src/mcp/context.js';
  * A stand-in for the hosted /mcp: stateless Streamable HTTP, one server per
  * POST, as the API runs it. Records each call and the auth header it saw.
  */
-function startHosted(): Promise<{ calls: { args: unknown; auth?: string; name: string }[]; http: HttpServer; url: string }> {
+function startHosted(): Promise<{
+  calls: { args: unknown; auth?: string; name: string }[];
+  http: HttpServer;
+  inits: number;
+  url: string;
+}> {
   const calls: { args: unknown; auth?: string; name: string }[] = [];
+  const hosted = { calls, inits: 0 };
   const http = createHttpServer(async (req, res) => {
     // Stateless, as the API: no GET stream, no session to delete.
     if (req.method !== 'POST') {
@@ -30,6 +36,7 @@ function startHosted(): Promise<{ calls: { args: unknown; auth?: string; name: s
     const chunks: Buffer[] = [];
     for await (const c of req) chunks.push(c as Buffer);
     const body = JSON.parse(Buffer.concat(chunks).toString() || '{}');
+    if (body.method === 'initialize') hosted.inits++;
     const auth = req.headers['x-app-api-key'] as string | undefined;
     const server = new McpServer({ name: 'hosted', version: '1' });
     const record = (name: string) => async (args: unknown) => {
@@ -69,7 +76,7 @@ function startHosted(): Promise<{ calls: { args: unknown; auth?: string; name: s
   return new Promise((resolve) => {
     http.listen(0, '127.0.0.1', () => {
       const { port } = http.address() as AddressInfo;
-      resolve({ calls, http, url: `http://127.0.0.1:${port}` });
+      resolve(Object.assign(hosted, { http, url: `http://127.0.0.1:${port}` }));
     });
   });
 }
@@ -127,6 +134,30 @@ describe('dcd mcp bridge', () => {
     await client.close();
   });
 
+  it('keeps a running call when the session is renewed, and sends the new auth', async () => {
+    const client = await connect();
+    await client.listTools();
+    const slow = client.callTool({ name: 'get_logs', arguments: { ms: 300 } });
+    await new Promise((r) => setTimeout(r, 50));
+    // As if a `dcd login` session were renewed: getContext resolves new auth.
+    process.env.DEVICE_CLOUD_API_KEY = 'renewed-key';
+    clearContextCache();
+    await client.callTool({ name: 'inspect_screen', arguments: {} });
+    const result = await slow;
+    expect(result.isError).to.not.equal(true);
+    expect(JSON.stringify(result.content)).to.include('late');
+    expect(hosted.calls).to.deep.equal([{ name: 'inspect_screen', args: {}, auth: 'renewed-key' }]);
+    expect(hosted.inits).to.equal(1);
+    await client.close();
+  });
+
+  it('shares one connection between calls that arrive together', async () => {
+    const client = await connect();
+    await Promise.all([client.listTools(), client.listTools(), client.callTool({ name: 'inspect_screen', arguments: {} })]);
+    expect(hosted.inits).to.equal(1);
+    await client.close();
+  });
+
   it("applies the bridge's call timeout, not the SDK's 60s default", async () => {
     // The agent's own client allows long calls; only the bridge's limit applies.
     const client = await connect(300);