fix(gateway): trust bootstrap-paired backend handshakes

src/gateway/server/ws-connection/connect-policy.test.ts

@@ -5,6 +5,7 @@ import {
   evaluateMissingDeviceIdentity,
   isTrustedProxyControlUiOperatorAuth,
   resolveControlUiAuthPolicy,
+  resolveInternalBackendClientAttestation,
   shouldSkipBackendSelfPairing,
   shouldSkipControlUiPairing,
 } from "./connect-policy.js";
@@ -643,4 +644,56 @@ describe("ws connect policy", () => {
       }),
     ).toBe(false);
   });
+
+  test("promotes bootstrap-paired backend clients to internal attestation", () => {
+    const backendConnect: ConnectParams = {
+      client: {
+        id: GATEWAY_CLIENT_IDS.GATEWAY_CLIENT,
+        mode: GATEWAY_CLIENT_MODES.BACKEND,
+        version: "1.0.0",
+        platform: "node",
+      },
+      minProtocol: 1,
+      maxProtocol: 1,
+    };
+
+    expect(
+      resolveInternalBackendClientAttestation({
+        connectParams: backendConnect,
+        hasBrowserOriginHeader: false,
+        initialIsInternalBackendClient: false,
+        authMethod: "bootstrap-token",
+        deviceTokenIssued: true,
+      }),
+    ).toBe(true);
+
+    expect(
+      resolveInternalBackendClientAttestation({
+        connectParams: backendConnect,
+        hasBrowserOriginHeader: true,
+        initialIsInternalBackendClient: false,
+        authMethod: "bootstrap-token",
+        deviceTokenIssued: true,
+      }),
+    ).toBe(false);
+
+    expect(
+      resolveInternalBackendClientAttestation({
+        connectParams: {
+          client: {
+            id: "desktop",
+            mode: GATEWAY_CLIENT_MODES.TEST,
+            version: "1.0.0",
+            platform: "node",
+          },
+          minProtocol: 1,
+          maxProtocol: 1,
+        },
+        hasBrowserOriginHeader: false,
+        initialIsInternalBackendClient: false,
+        authMethod: "bootstrap-token",
+        deviceTokenIssued: true,
+      }),
+    ).toBe(false);
+  });
 });

src/gateway/server/ws-connection/connect-policy.ts

@@ -113,6 +113,25 @@ export function shouldSkipBackendSelfPairing(params: {
   );
 }
 
+export function resolveInternalBackendClientAttestation(params: {
+  connectParams: ConnectParams;
+  hasBrowserOriginHeader: boolean;
+  initialIsInternalBackendClient: boolean;
+  authMethod: GatewayAuthResult["method"];
+  deviceTokenIssued: boolean;
+}): boolean {
+  if (params.initialIsInternalBackendClient) {
+    return true;
+  }
+  const isGatewayBackendClient =
+    params.connectParams.client.id === GATEWAY_CLIENT_IDS.GATEWAY_CLIENT &&
+    params.connectParams.client.mode === GATEWAY_CLIENT_MODES.BACKEND;
+  if (!isGatewayBackendClient || params.hasBrowserOriginHeader) {
+    return false;
+  }
+  return params.authMethod === "bootstrap-token" && params.deviceTokenIssued;
+}
+
 export type MissingDeviceIdentityDecision =
   | { kind: "allow" }
   | { kind: "reject-control-ui-insecure-auth" }

src/gateway/server/ws-connection/message-handler.ts

@@ -83,6 +83,7 @@ import {
   evaluateMissingDeviceIdentity,
   isTrustedProxyControlUiOperatorAuth,
   resolveControlUiAuthPolicy,
+  resolveInternalBackendClientAttestation,
   shouldSkipBackendSelfPairing,
   shouldSkipControlUiPairing,
 } from "./connect-policy.js";
@@ -891,6 +892,13 @@ export function attachGatewayWsMessageHandler(params: {
         const deviceToken = device
           ? await ensureDeviceToken({ deviceId: device.id, role, scopes })
           : null;
+        const attestedInternalBackendClient = resolveInternalBackendClientAttestation({
+          connectParams,
+          hasBrowserOriginHeader,
+          initialIsInternalBackendClient: isInternalBackendClient,
+          authMethod,
+          deviceTokenIssued: deviceToken !== null,
+        });
 
         if (role === "node") {
           const cfg = loadConfig();
@@ -995,7 +1003,7 @@ export function attachGatewayWsMessageHandler(params: {
           canvasHostUrl,
           canvasCapability,
           canvasCapabilityExpiresAtMs,
-          isInternalBackendClient,
+          isInternalBackendClient: attestedInternalBackendClient,
         };
         setSocketMaxPayload(socket, MAX_PAYLOAD_BYTES);
         setClient(nextClient);