diff --git a/source/cydo/web/transport.d b/source/cydo/web/transport.d
index e1c6ddb8..cca84b02 100644
--- a/source/cydo/web/transport.d
+++ b/source/cydo/web/transport.d
@@ -2,7 +2,7 @@ module cydo.web.transport;
 
 import std.conv : ConvException, to;
 import std.file : exists, isFile, remove;
-import std.logger : infof, warningf;
+import std.logger : fatalf, infof, warningf;
 import std.path : buildPath;
 
 import ae.net.asockets : DisconnectType, onNextTick, socketManager;
@@ -78,6 +78,10 @@ class TransportAdapter
 	private string webDistDir_;
 	private string authUser_;
 	private string authPass_;
+	// session cookie token, regenerated whenever auth credentials are set; old
+	// iOS Safari never sends the Authorization header on WebSocket upgrades, so
+	// /ws authenticates via this cookie instead
+	private string authCookieToken_;
 	private WebSocketCallbacks websocketCallbacks_;
 	private RawSourceLookupResult delegate(int tid, size_t seq) rawSourceLookup_;
 	private McpCallbacks mcpCallbacks_;
@@ -99,6 +103,16 @@ class TransportAdapter
 	{
 		authUser_ = user;
 		authPass_ = pass;
+		if (authEnabled)
+		{
+			import std.file : read;
+			import std.format : format;
+
+			auto entropy = cast(ubyte[]) read("/dev/urandom", 32);
+			if (entropy.length != 32)
+				fatalf("Short read from /dev/urandom (%d bytes)", entropy.length);
+			authCookieToken_ = format("%(%02x%)", entropy);
+		}
 	}
 
 	void startHttpServer(string sslCert, string sslKey)
@@ -208,13 +222,27 @@ class TransportAdapter
 			"object-src 'none'; " ~
 			"base-uri 'self'; " ~
 			"frame-ancestors 'none'";
+		// hand a session cookie to clients that authenticated via basic auth; it
+		// rides along on WebSocket upgrades where old Safari omits the
+		// Authorization header
+		if (authCookieToken_.length > 0 && !hasValidAuthCookie(request))
+			response.headers["Set-Cookie"] =
+				"cydo_auth=" ~ authCookieToken_ ~ "; Path=/; HttpOnly; SameSite=Strict";
 		conn.sendResponse(response);
 	}
 
+	private bool hasValidAuthCookie(HttpRequest request)
+	{
+		return authCookieToken_.length > 0
+			&& request.getCookies().get("cydo_auth", null) == authCookieToken_;
+	}
+
 	private bool checkAuth(HttpRequest request, HttpServerConnection conn)
 	{
 		if (!authEnabled)
 			return true;
+		if (hasValidAuthCookie(request))
+			return true;
 		auto response = new HttpResponseEx();
 		if (!response.authorize(request, (reqUser, reqPass) => reqUser == authUser_ && reqPass == authPass_))
 		{
diff --git a/tests/e2e/websocket-cookie-auth.spec.ts b/tests/e2e/websocket-cookie-auth.spec.ts
new file mode 100644
index 00000000..c4f7f52d
--- /dev/null
+++ b/tests/e2e/websocket-cookie-auth.spec.ts
@@ -0,0 +1,67 @@
+import { request as httpRequest } from "http";
+import { test, expect } from "./fixtures";
+
+test.use({
+  backendEnv: {
+    CYDO_AUTH_USER: "user",
+    CYDO_AUTH_PASS: "test-pass",
+  },
+  httpCredentials: {
+    username: "user",
+    password: "test-pass",
+  },
+});
+
+/** Attempt a bare WebSocket upgrade handshake with exactly the given extra
+ *  headers, resolving with the HTTP status the server answered. */
+function upgradeStatus(headers: Record<string, string>): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const req = httpRequest({
+      host: "localhost",
+      port: 3940,
+      path: "/ws",
+      headers: {
+        Connection: "Upgrade",
+        Upgrade: "websocket",
+        "Sec-WebSocket-Version": "13",
+        "Sec-WebSocket-Key": "AAAAAAAAAAAAAAAAAAAAAA==",
+        ...headers,
+      },
+    });
+    req.on("upgrade", (res, socket) => {
+      socket.destroy();
+      resolve(res.statusCode ?? 0);
+    });
+    req.on("response", (res) => {
+      res.destroy();
+      resolve(res.statusCode ?? 0);
+    });
+    req.on("error", reject);
+    req.end();
+  });
+}
+
+test(
+  "websocket upgrade authenticates via the session cookie alone",
+  { tag: "@claude-only" },
+  async ({ page }) => {
+    await page.goto("/");
+    await expect(page.locator('button[title="New task"]').first()).toBeVisible({
+      timeout: 15_000,
+    });
+
+    const cookies = await page.context().cookies();
+    const auth = cookies.find((cookie) => cookie.name === "cydo_auth");
+    expect(auth).toBeTruthy();
+
+    // WebKit on old iOS Safari omits the Authorization header on upgrade
+    // requests, so the cookie must carry the handshake entirely on its own.
+    expect(await upgradeStatus({ Cookie: `cydo_auth=${auth!.value}` })).toBe(
+      101,
+    );
+
+    // And the cookie is load-bearing: an upgrade with no credentials at all
+    // stays rejected.
+    expect(await upgradeStatus({})).toBe(401);
+  },
+);