diff --git a/eslint.config.js b/eslint.config.js
index cf5b0f1..38a7191 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -75,7 +75,7 @@ export default defineConfig([
 			'react-dom/no-missing-button-type': 'off',
 			'react-x/no-nested-component-definitions': 'off',
 			'@typescript-eslint/prefer-optional-chain': 'off',
-			'@typescript-eslint/use-unknown-in-catch-callback-variable': 'warn',
+			'@typescript-eslint/use-unknown-in-catch-callback-variable': 'off',
 			'@typescript-eslint/no-unnecessary-type-parameters': 'off',
 
 			// 'require-await': 'off',
diff --git a/packages/extension/src/entrypoints/background.ts b/packages/extension/src/entrypoints/background.ts
index d6a47ca..4a667c4 100644
--- a/packages/extension/src/entrypoints/background.ts
+++ b/packages/extension/src/entrypoints/background.ts
@@ -65,6 +65,7 @@ async function handleRPCCall(msg: RPCCallMessage): Promise<void> {
 
 	// Create message for content script
 	const csMessage: CSRPCMessage = {
+		isPageAgentMessage: true,
 		type: 'cs:rpc',
 		id,
 		method,
@@ -77,6 +78,7 @@ async function handleRPCCall(msg: RPCCallMessage): Promise<void> {
 
 		// Forward response back to sidepanel
 		const response: RPCResponseMessage = {
+			isPageAgentMessage: true,
 			type: 'rpc:response',
 			id,
 			success: true,
@@ -86,6 +88,7 @@ async function handleRPCCall(msg: RPCCallMessage): Promise<void> {
 	} catch (error) {
 		// Forward error back to sidepanel
 		const response: RPCResponseMessage = {
+			isPageAgentMessage: true,
 			type: 'rpc:response',
 			id,
 			success: false,
@@ -117,6 +120,7 @@ async function handleCSQuery(
 		// Forward response back to content script
 		if (sender.tab?.id) {
 			const queryResponse: QueryResponseMessage = {
+				isPageAgentMessage: true,
 				type: 'query:response',
 				id,
 				result: response,
@@ -127,6 +131,7 @@ async function handleCSQuery(
 		// Sidepanel not open or no response, return default
 		if (sender.tab?.id) {
 			const queryResponse: QueryResponseMessage = {
+				isPageAgentMessage: true,
 				type: 'query:response',
 				id,
 				result: queryType === 'shouldShowMask' ? false : null,
@@ -145,6 +150,7 @@ async function handleCSQuery(
  */
 chrome.tabs.onRemoved.addListener((tabId) => {
 	const message: TabEventMessage = {
+		isPageAgentMessage: true,
 		type: 'tab:event',
 		id: generateMessageId(),
 		eventType: 'removed',
@@ -163,6 +169,7 @@ chrome.tabs.onUpdated.addListener((tabId, changeInfo) => {
 	if (!changeInfo.status) return
 
 	const message: TabEventMessage = {
+		isPageAgentMessage: true,
 		type: 'tab:event',
 		id: generateMessageId(),
 		eventType: 'updated',
@@ -182,6 +189,7 @@ chrome.tabs.onUpdated.addListener((tabId, changeInfo) => {
  */
 chrome.tabs.onActivated.addListener((activeInfo) => {
 	const message: TabEventMessage = {
+		isPageAgentMessage: true,
 		type: 'tab:event',
 		id: generateMessageId(),
 		eventType: 'activated',
@@ -202,6 +210,7 @@ chrome.windows.onFocusChanged.addListener((windowId) => {
 	// windowId is chrome.windows.WINDOW_ID_NONE (-1) when all windows lose focus
 	const focused = windowId !== chrome.windows.WINDOW_ID_NONE
 	const message: TabEventMessage = {
+		isPageAgentMessage: true,
 		type: 'tab:event',
 		id: generateMessageId(),
 		eventType: 'windowFocusChanged',
diff --git a/packages/extension/src/entrypoints/content.ts b/packages/extension/src/entrypoints/content.ts
index 06314cb..baae6fc 100644
--- a/packages/extension/src/entrypoints/content.ts
+++ b/packages/extension/src/entrypoints/content.ts
@@ -11,12 +11,7 @@
  */
 import { PageController } from '@page-agent/page-controller'
 
-import type {
-	CSQueryMessage,
-	CSRPCMessage,
-	QueryResponseMessage,
-	RPCMethod,
-} from '../messaging/protocol'
+import type { CSQueryMessage, CSRPCMessage, QueryResponseMessage } from '../messaging/protocol'
 import { generateMessageId, isExtensionMessage } from '../messaging/protocol'
 
 const DEBUG_PREFIX = '[ContentScript]'
@@ -86,6 +81,7 @@ async function queryShouldShowMask(getController: () => PageController): Promise
 
 	const queryId = generateMessageId()
 	const queryMessage: CSQueryMessage = {
+		isPageAgentMessage: true,
 		type: 'cs:query',
 		id: queryId,
 		queryType: 'shouldShowMask',
@@ -198,7 +194,7 @@ function registerRPCHandler(
  * Handle an RPC call
  */
 async function handleRPCCall(
-	method: RPCMethod,
+	method: string,
 	args: unknown[],
 	getController: () => PageController,
 	getControllerIfExists: () => PageController | null,
diff --git a/packages/extension/src/messaging/protocol.ts b/packages/extension/src/messaging/protocol.ts
index b08af0a..18a13de 100644
--- a/packages/extension/src/messaging/protocol.ts
+++ b/packages/extension/src/messaging/protocol.ts
@@ -61,6 +61,7 @@ type MessageType =
 
 /** Base message structure */
 interface BaseMessage {
+	isPageAgentMessage: true
 	type: MessageType
 	id: string // Unique message ID for request-response matching
 }
@@ -69,28 +70,11 @@ interface BaseMessage {
 // RPC Messages (SidePanel ↔ SW ↔ ContentScript)
 // ============================================================================
 
-/** RPC method names matching PageController interface */
-export type RPCMethod =
-	| 'getCurrentUrl'
-	| 'getLastUpdateTime'
-	| 'getBrowserState'
-	| 'updateTree'
-	| 'cleanUpHighlights'
-	| 'clickElement'
-	| 'inputText'
-	| 'selectOption'
-	| 'scroll'
-	| 'scrollHorizontally'
-	| 'executeJavascript'
-	| 'showMask'
-	| 'hideMask'
-	| 'dispose'
-
 /** SidePanel → SW: Request to call PageController method */
 export interface RPCCallMessage extends BaseMessage {
 	type: 'rpc:call'
 	tabId: number
-	method: RPCMethod
+	method: string
 	args: unknown[]
 }
 
@@ -105,7 +89,7 @@ export interface RPCResponseMessage extends BaseMessage {
 /** SW → ContentScript: Forwarded RPC call */
 export interface CSRPCMessage extends BaseMessage {
 	type: 'cs:rpc'
-	method: RPCMethod
+	method: string
 	args: unknown[]
 }
 
@@ -179,9 +163,7 @@ export function isExtensionMessage(msg: unknown): msg is ExtensionMessage {
 	return (
 		typeof msg === 'object' &&
 		msg !== null &&
-		'type' in msg &&
-		'id' in msg &&
-		typeof (msg as ExtensionMessage).type === 'string' &&
-		typeof (msg as ExtensionMessage).id === 'string'
+		'isPageAgentMessage' in msg &&
+		(msg as any).isPageAgentMessage === true
 	)
 }
diff --git a/packages/extension/src/messaging/rpc.ts b/packages/extension/src/messaging/rpc.ts
index 2412dd9..fa82b19 100644
--- a/packages/extension/src/messaging/rpc.ts
+++ b/packages/extension/src/messaging/rpc.ts
@@ -10,7 +10,6 @@ import {
 	type ActionResult,
 	type BrowserState,
 	type RPCCallMessage,
-	type RPCMethod,
 	type RPCResponseMessage,
 	type ScrollHorizontallyOptions,
 	type ScrollOptions,
@@ -107,11 +106,12 @@ export class RPCError extends Error {
 /**
  * Make a single RPC call (no retry)
  */
-async function callOnce(tabId: number, method: RPCMethod, args: unknown[]): Promise<unknown> {
+async function callOnce(tabId: number, method: string, args: unknown[]): Promise<unknown> {
 	ensureResponseListener()
 
 	const id = generateMessageId()
 	const message: RPCCallMessage = {
+		isPageAgentMessage: true,
 		type: 'rpc:call',
 		id,
 		tabId,
@@ -138,7 +138,7 @@ async function callOnce(tabId: number, method: RPCMethod, args: unknown[]): Prom
 /**
  * Make an RPC call with retry logic
  */
-async function call(tabId: number, method: RPCMethod, args: unknown[]): Promise<unknown> {
+async function call(tabId: number, method: string, args: unknown[]): Promise<unknown> {
 	let lastError: Error | null = null
 
 	for (let attempt = 0; attempt < RPC_CONFIG.maxRetries; attempt++) {