diff --git a/ext/src/background/ReceiverSelector.ts b/ext/src/background/ReceiverSelector.ts
index 5ac8f2a..773774b 100644
--- a/ext/src/background/ReceiverSelector.ts
+++ b/ext/src/background/ReceiverSelector.ts
@@ -67,7 +67,8 @@ export default class ReceiverSelector extends TypedEventTarget<ReceiverSelectorE
     private wasReceiverSelected = false;
 
     private appId?: string;
-    private pageInfo?: ReceiverSelectorPageInfo;
+
+    pageInfo?: ReceiverSelectorPageInfo;
 
     constructor() {
         super();
diff --git a/ext/src/background/castManager.ts b/ext/src/background/castManager.ts
index a93705a..d1c79d2 100644
--- a/ext/src/background/castManager.ts
+++ b/ext/src/background/castManager.ts
@@ -93,7 +93,7 @@ export default new (class {
 
         instance.contentPort.postMessage({
             subject: "cast:initialized",
-            data: await bridge.getInfo()
+            data: { isAvailable: (await bridge.getInfo()).isVersionCompatible }
         });
 
         return instance;
@@ -197,12 +197,26 @@ export default new (class {
     ) {
         // Intercept messages to store relevant info
         switch (message.subject) {
-            case "cast:sessionCreated":
+            case "cast:sessionCreated": {
+                // Close after session is created
+                const selector = ReceiverSelector.sharedInstance;
+                if (
+                    selector.isOpen &&
+                    // If selector context is the same as the instance context
+                    selector.pageInfo?.tabId === instance.contentTabId &&
+                    selector.pageInfo?.frameId === instance.contentFrameId &&
+                    // If selector is supposed to close
+                    (await options.get("receiverSelectorWaitForConnection"))
+                ) {
+                    selector.close();
+                }
+
                 instance.session = {
                     deviceId: message.data.receiverId,
                     sessionId: message.data.sessionId
                 };
                 break;
+            }
         }
 
         instance.contentPort.postMessage(message);
@@ -296,23 +310,6 @@ export default new (class {
 
                 break;
             }
-
-            /**
-             * TODO: If we're closing a selector, make sure it's the
-             * same one that caused the session creation.
-             */
-            case "main:closeReceiverSelector": {
-                const selector = ReceiverSelector.sharedInstance;
-                const shouldClose = await options.get(
-                    "receiverSelectorWaitForConnection"
-                );
-
-                if (selector.isOpen && shouldClose) {
-                    selector.close();
-                }
-
-                break;
-            }
         }
     }
 
diff --git a/ext/src/cast/export.ts b/ext/src/cast/export.ts
index ea67298..dcf6057 100644
--- a/ext/src/cast/export.ts
+++ b/ext/src/cast/export.ts
@@ -97,9 +97,7 @@ export function ensureInit(): Promise<TypedMessagePort<Message>> {
         function handleIncomingMessageToCast(message: Message) {
             switch (message.subject) {
                 case "cast:initialized": {
-                    initializedBridgeInfo = message.data;
-
-                    if (initializedBridgeInfo.isVersionCompatible) {
+                    if (message.data.isAvailable) {
                         resolve(initializedBackgroundPort);
                     } else {
                         reject();
diff --git a/ext/src/cast/index.ts b/ext/src/cast/index.ts
index 1de6adc..4ad377f 100644
--- a/ext/src/cast/index.ts
+++ b/ext/src/cast/index.ts
@@ -49,7 +49,7 @@ eventMessaging.page.addListener(async message => {
             // Call page script/framework API script's init function
             const initFn = _window.__onGCastApiAvailable;
             if (initFn && typeof initFn === "function") {
-                initFn(message.data.isVersionCompatible);
+                initFn(message.data.isAvailable);
             }
 
             break;
diff --git a/ext/src/cast/sdk/index.ts b/ext/src/cast/sdk/index.ts
index cadc5f0..f4f7e9f 100644
--- a/ext/src/cast/sdk/index.ts
+++ b/ext/src/cast/sdk/index.ts
@@ -143,11 +143,6 @@ export default class {
              * and data needed to create cast API objects is sent.
              */
             case "cast:sessionCreated": {
-                // Notify background to close UI
-                eventMessaging.page.sendMessage({
-                    subject: "main:closeReceiverSelector"
-                });
-
                 const status = message.data;
                 const receiverDevice = this.#receiverDevices.get(
                     status.receiverId
diff --git a/ext/src/messaging.ts b/ext/src/messaging.ts
index efec414..f998f5c 100644
--- a/ext/src/messaging.ts
+++ b/ext/src/messaging.ts
@@ -1,7 +1,6 @@
 "use strict";
 
 import type { TypedPort } from "./lib/TypedPort";
-import type { BridgeInfo } from "./lib/bridge";
 
 import type {
     ReceiverSelection,
@@ -39,6 +38,7 @@ import type { ReceiverDevice, ReceiverSelectorMediaType } from "./types";
  * components.
  */
 type ExtMessageDefinitions = {
+    /** Initial data to send to selector popup. */
     "popup:init": {
         appId?: string;
         pageInfo?: {
@@ -47,30 +47,49 @@ type ExtMessageDefinitions = {
             frameId: number;
         };
     };
+    /** Updates selector popup with new data. */
     "popup:update": {
         receiverDevices: ReceiverDevice[];
         defaultMediaType?: ReceiverSelectorMediaType;
         availableMediaTypes?: ReceiverSelectorMediaType;
     };
-    "popup:close": undefined;
 
+    /**
+     * Sent from the selector popup when a receiver has been
+     * selected.
+     */
     "main:receiverSelected": ReceiverSelection;
+    /**
+     * Sent from the selector popup when a receiver has been
+     * stopped. Used to provide cast API receiver action updates.
+     */
     "main:receiverStopped": { deviceId: string };
+    /** Allows the selector popup to send cast NS_RECEIVER messages. */
     "main:sendReceiverMessage": ReceiverSelectorReceiverMessage;
+    /** Allows the selector popup to send cast NS_MEDIA messages. */
     "main:sendMediaMessage": ReceiverSelectorMediaMessage;
 
+    /**
+     * Sent from the cast API to trigger receiver selection on session
+     * request.
+     */
     "main:selectReceiver": {
         sessionRequest: SessionRequest;
     };
+    /** Return message to the cast API when a receiver is selected. */
     "cast:selectReceiver/selected": ReceiverSelection;
+    /** Return message to the cast API when a selection is cancelled. */
     "cast:selectReceiver/cancelled": undefined;
 
+    /** Sent to the cast API when a receiver app is stopped. */
     "cast:receiverStoppedAction": { deviceId: string };
 
-    "main:closeReceiverSelector": undefined;
-
+    /**
+     * Tells the cast manager to provide the cast API instance with
+     * receiver data.
+     */
     "main:initializeCast": { appId: string };
-    "cast:initialized": BridgeInfo;
+    "cast:initialized": { isAvailable: boolean };
 
     "cast:receiverDeviceUp": { receiverDevice: ReceiverDevice };
     "cast:receiverDeviceDown": { receiverDeviceId: string };
diff --git a/ext/src/ui/popup/Popup.svelte b/ext/src/ui/popup/Popup.svelte
index 337531f..1beb63a 100644
--- a/ext/src/ui/popup/Popup.svelte
+++ b/ext/src/ui/popup/Popup.svelte
@@ -152,10 +152,6 @@
                 pageInfo = message.data.pageInfo;
                 break;
 
-            case "popup:close":
-                window.close();
-                break;
-
             case "popup:update": {
                 if (
                     message.data.availableMediaTypes !== undefined &&