diff --git a/.github/workflows/label-alpha-release.yml b/.github/workflows/label-alpha-release.yml
index b3d34682d..ab149f050 100644
--- a/.github/workflows/label-alpha-release.yml
+++ b/.github/workflows/label-alpha-release.yml
@@ -48,6 +48,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: '18'
+          registry-url: https://registry.npmjs.org
           cache: 'pnpm'
       - run: pnpm install
 
diff --git a/src/__tests__/extensions/exception-autocapture/exception-observer.test.ts b/src/__tests__/extensions/exception-autocapture/exception-observer.test.ts
index cffc71572..2070a2c41 100644
--- a/src/__tests__/extensions/exception-autocapture/exception-observer.test.ts
+++ b/src/__tests__/extensions/exception-autocapture/exception-observer.test.ts
@@ -42,7 +42,7 @@ describe('Exception Observer', () => {
         // assignableWindow.onerror = jest.fn()
         // assignableWindow.onerror__POSTHOG_INSTRUMENTED__ = true
 
-        assignableWindow.posthogErrorHandlers = posthogErrorWrappingFunctions
+        assignableWindow.__PosthogExtensions__.errorWrappingFunctions = posthogErrorWrappingFunctions
     }
 
     beforeEach(async () => {
diff --git a/src/__tests__/extensions/replay/sessionrecording.test.ts b/src/__tests__/extensions/replay/sessionrecording.test.ts
index f300af56d..fd26a40c6 100644
--- a/src/__tests__/extensions/replay/sessionrecording.test.ts
+++ b/src/__tests__/extensions/replay/sessionrecording.test.ts
@@ -134,19 +134,21 @@ describe('SessionRecording', () => {
     let addCaptureHookMock: Mock
 
     const addRRwebToWindow = () => {
-        assignableWindow.rrweb = {
+        assignableWindow.__PosthogExtensions__.rrweb = {
             record: jest.fn(({ emit }) => {
                 _emit = emit
                 return () => {}
             }),
+            version: 'fake',
+            rrwebVersion: 'fake',
         }
-        assignableWindow.rrweb.record.takeFullSnapshot = jest.fn(() => {
+        assignableWindow.__PosthogExtensions__.rrweb.record.takeFullSnapshot = jest.fn(() => {
             // we pretend to be rrweb and call emit
             _emit(createFullSnapshot())
         })
-        assignableWindow.rrweb.record.addCustomEvent = _addCustomEvent
+        assignableWindow.__PosthogExtensions__.rrweb.record.addCustomEvent = _addCustomEvent
 
-        assignableWindow.rrwebConsoleRecord = {
+        assignableWindow.__PosthogExtensions__.rrwebPlugins = {
             getRecordConsolePlugin: jest.fn(),
         }
     }
@@ -165,8 +167,13 @@ describe('SessionRecording', () => {
             persistence: 'memory',
         } as unknown as PostHogConfig
 
-        assignableWindow.rrweb = undefined
-        assignableWindow.rrwebConsoleRecord = undefined
+        assignableWindow.__PosthogExtensions__ = {
+            rrweb: undefined,
+            rrwebPlugins: {
+                getRecordConsolePlugin: undefined,
+                getRecordNetworkPlugin: undefined,
+            },
+        }
 
         sessionIdGeneratorMock = jest.fn().mockImplementation(() => sessionId)
         windowIdGeneratorMock = jest.fn().mockImplementation(() => 'windowId')
@@ -636,7 +643,7 @@ describe('SessionRecording', () => {
                 sessionRecording.startIfEnabledOrStop()
 
                 sessionRecording['_onScriptLoaded']()
-                expect(assignableWindow.rrweb.record).toHaveBeenCalledWith(
+                expect(assignableWindow.__PosthogExtensions__.rrweb.record).toHaveBeenCalledWith(
                     expect.objectContaining({
                         recordCanvas: true,
                         sampling: { canvas: 6 },
@@ -659,7 +666,7 @@ describe('SessionRecording', () => {
 
                 sessionRecording['_onScriptLoaded']()
 
-                const mockParams = assignableWindow.rrweb.record.mock.calls[0][0]
+                const mockParams = assignableWindow.__PosthogExtensions__.rrweb.record.mock.calls[0][0]
                 expect(mockParams).not.toHaveProperty('recordCanvas')
                 expect(mockParams).not.toHaveProperty('canvasFps')
                 expect(mockParams).not.toHaveProperty('canvasQuality')
@@ -672,7 +679,7 @@ describe('SessionRecording', () => {
             sessionRecording.startIfEnabledOrStop()
             // maskAllInputs should change from default
             // someUnregisteredProp should not be present
-            expect(assignableWindow.rrweb.record).toHaveBeenCalledWith({
+            expect(assignableWindow.__PosthogExtensions__.rrweb.record).toHaveBeenCalledWith({
                 emit: expect.anything(),
                 maskAllInputs: false,
                 blockClass: 'ph-no-capture',
@@ -700,7 +707,7 @@ describe('SessionRecording', () => {
             ])('%s', (_name: string, session_recording: SessionRecordingOptions, expected: boolean) => {
                 posthog.config.session_recording = session_recording
                 sessionRecording.startIfEnabledOrStop()
-                expect(assignableWindow.rrweb.record).toHaveBeenCalledWith(
+                expect(assignableWindow.__PosthogExtensions__.rrweb.record).toHaveBeenCalledWith(
                     expect.objectContaining({
                         maskInputOptions: expect.objectContaining({ password: expected }),
                     })
@@ -999,7 +1006,9 @@ describe('SessionRecording', () => {
 
                 sessionRecording.startIfEnabledOrStop()
 
-                expect(assignableWindow.rrwebConsoleRecord.getRecordConsolePlugin).not.toHaveBeenCalled()
+                expect(
+                    assignableWindow.__PosthogExtensions__.rrwebPlugins.getRecordConsolePlugin
+                ).not.toHaveBeenCalled()
             })
 
             it('if enabled, plugin is used', () => {
@@ -1007,7 +1016,7 @@ describe('SessionRecording', () => {
 
                 sessionRecording.startIfEnabledOrStop()
 
-                expect(assignableWindow.rrwebConsoleRecord.getRecordConsolePlugin).toHaveBeenCalled()
+                expect(assignableWindow.__PosthogExtensions__.rrwebPlugins.getRecordConsolePlugin).toHaveBeenCalled()
             })
         })
 
@@ -1246,7 +1255,7 @@ describe('SessionRecording', () => {
             startingTimestamp = sessionRecording['_lastActivityTimestamp']
             expect(startingTimestamp).toBeGreaterThan(0)
 
-            expect(assignableWindow.rrweb.record.takeFullSnapshot).toHaveBeenCalledTimes(0)
+            expect(assignableWindow.__PosthogExtensions__.rrweb.record.takeFullSnapshot).toHaveBeenCalledTimes(0)
 
             // the buffer starts out empty
             expect(sessionRecording['buffer']).toEqual({
diff --git a/src/__tests__/surveys.test.ts b/src/__tests__/surveys.test.ts
index aed07e393..0074a3bf0 100644
--- a/src/__tests__/surveys.test.ts
+++ b/src/__tests__/surveys.test.ts
@@ -129,7 +129,7 @@ describe('surveys', () => {
 
         loadScriptMock.mockImplementation((_path, callback) => {
             assignableWindow.__PosthogExtensions__ = assignableWindow.__Posthog__ || {}
-            assignableWindow.extendPostHogWithSurveys = generateSurveys
+            assignableWindow.__PosthogExtensions__.generateSurveys = generateSurveys
             assignableWindow.__PosthogExtensions__.canActivateRepeatedly = canActivateRepeatedly
 
             callback()
diff --git a/src/entrypoints/exception-autocapture.ts b/src/entrypoints/exception-autocapture.ts
index f1411b62d..07dd05bad 100644
--- a/src/entrypoints/exception-autocapture.ts
+++ b/src/entrypoints/exception-autocapture.ts
@@ -1,5 +1,5 @@
 import { errorToProperties, unhandledRejectionToProperties } from '../extensions/exception-autocapture/error-conversion'
-import { window } from '../utils/globals'
+import { assignableWindow, window } from '../utils/globals'
 import { ErrorEventArgs, Properties } from '../types'
 import { logger } from '../utils/logger'
 
@@ -49,9 +49,16 @@ const posthogErrorWrappingFunctions = {
     wrapUnhandledRejection,
 }
 
-if (window) {
-    ;(window as any).posthogErrorWrappingFunctions = posthogErrorWrappingFunctions
-    ;(window as any).parseErrorAsProperties = errorToProperties
-}
+assignableWindow.__PosthogExtensions__ = assignableWindow.__PosthogExtensions__ || {}
+assignableWindow.__PosthogExtensions__.errorWrappingFunctions = posthogErrorWrappingFunctions
+assignableWindow.__PosthogExtensions__.parseErrorAsProperties = errorToProperties
+
+// we used to put these on window, and now we put them on __PosthogExtensions__
+// but that means that old clients which lazily load this extension are looking in the wrong place
+// yuck,
+// so we also put them directly on the window
+// when 1.161.1 is the oldest version seen in production we can remove this
+assignableWindow.posthogErrorWrappingFunctions = posthogErrorWrappingFunctions
+assignableWindow.parseErrorAsProperties = errorToProperties
 
 export default posthogErrorWrappingFunctions
diff --git a/src/entrypoints/recorder.ts b/src/entrypoints/recorder.ts
index a2f41db5c..fe0f4a9af 100644
--- a/src/entrypoints/recorder.ts
+++ b/src/entrypoints/recorder.ts
@@ -30,7 +30,7 @@ import {
     isUndefined,
 } from '../utils/type-utils'
 import { logger } from '../utils/logger'
-import { window } from '../utils/globals'
+import { assignableWindow } from '../utils/globals'
 import { defaultNetworkOptions } from '../extensions/replay/config'
 import { formDataToQuery } from '../utils/request-utils'
 import { patch } from '../extensions/replay/rrweb-plugins/patch'
@@ -674,10 +674,17 @@ export const getRecordNetworkPlugin: (options?: NetworkRecordOptions) => RecordP
 
 // rrweb/networ@1 ends
 
-if (window) {
-    ;(window as any).rrweb = { record: rrwebRecord, version: 'v2', rrwebVersion: version }
-    ;(window as any).rrwebConsoleRecord = { getRecordConsolePlugin }
-    ;(window as any).getRecordNetworkPlugin = getRecordNetworkPlugin
-}
+assignableWindow.__PosthogExtensions__ = assignableWindow.__PosthogExtensions__ || {}
+assignableWindow.__PosthogExtensions__.rrwebPlugins = { getRecordConsolePlugin, getRecordNetworkPlugin }
+assignableWindow.__PosthogExtensions__.rrweb = { record: rrwebRecord, version: 'v2', rrwebVersion: version }
+
+// we used to put all of these items directly on window, and now we put it on __PosthogExtensions__
+// but that means that old clients which lazily load this extension are looking in the wrong place
+// yuck,
+// so we also put them directly on the window
+// when 1.161.1 is the oldest version seen in production we can remove this
+assignableWindow.rrweb = { record: rrwebRecord, version: 'v2', rrwebVersion: version }
+assignableWindow.rrwebConsoleRecord = { getRecordConsolePlugin }
+assignableWindow.getRecordNetworkPlugin = getRecordNetworkPlugin
 
 export default rrwebRecord
diff --git a/src/entrypoints/surveys.ts b/src/entrypoints/surveys.ts
index 12606dffb..4baba2ca7 100644
--- a/src/entrypoints/surveys.ts
+++ b/src/entrypoints/surveys.ts
@@ -1,12 +1,14 @@
 import { generateSurveys } from '../extensions/surveys'
 
-import { window } from '../utils/globals'
+import { assignableWindow } from '../utils/globals'
 import { canActivateRepeatedly } from '../extensions/surveys/surveys-utils'
 
-if (window) {
-    ;(window as any).__PosthogExtensions__ = (window as any).__PosthogExtensions__ || {}
-    ;(window as any).__PosthogExtensions__.canActivateRepeatedly = canActivateRepeatedly
-    ;(window as any).extendPostHogWithSurveys = generateSurveys
-}
+assignableWindow.__PosthogExtensions__ = assignableWindow.__PosthogExtensions__ || {}
+assignableWindow.__PosthogExtensions__.canActivateRepeatedly = canActivateRepeatedly
+assignableWindow.__PosthogExtensions__.generateSurveys = generateSurveys
+
+// this used to be directly on window, but we moved it to __PosthogExtensions__
+// it is still on window for backwards compatibility
+assignableWindow.extendPostHogWithSurveys = generateSurveys
 
 export default generateSurveys
diff --git a/src/entrypoints/tracing-headers.ts b/src/entrypoints/tracing-headers.ts
index 2d76e52f1..06abc4e01 100644
--- a/src/entrypoints/tracing-headers.ts
+++ b/src/entrypoints/tracing-headers.ts
@@ -56,9 +56,18 @@ const patchXHR = (sessionManager: SessionIdManager): (() => void) => {
     )
 }
 
-if (assignableWindow) {
-    assignableWindow.postHogTracingHeadersPatchFns = {
-        _patchFetch: patchFetch,
-        _patchXHR: patchXHR,
-    }
+assignableWindow.__PosthogExtensions__ = assignableWindow.__PosthogExtensions__ || {}
+const patchFns = {
+    _patchFetch: patchFetch,
+    _patchXHR: patchXHR,
 }
+assignableWindow.__PosthogExtensions__.tracingHeadersPatchFns = patchFns
+
+// we used to put tracingHeadersPatchFns on window, and now we put it on __PosthogExtensions__
+// but that means that old clients which lazily load this extension are looking in the wrong place
+// yuck,
+// so we also put it directly on the window
+// when 1.161.1 is the oldest version seen in production we can remove this
+assignableWindow.postHogTracingHeadersPatchFns = patchFns
+
+export default patchFns
diff --git a/src/extensions/exception-autocapture/index.ts b/src/extensions/exception-autocapture/index.ts
index d820812b5..be1996015 100644
--- a/src/extensions/exception-autocapture/index.ts
+++ b/src/extensions/exception-autocapture/index.ts
@@ -1,4 +1,4 @@
-import { window } from '../../utils/globals'
+import { assignableWindow, window } from '../../utils/globals'
 import { PostHog } from '../../posthog-core'
 import { DecideResponse, Properties } from '../../types'
 
@@ -60,8 +60,9 @@ export class ExceptionObserver {
             return
         }
 
-        const wrapOnError = (window as any).posthogErrorWrappingFunctions.wrapOnError
-        const wrapUnhandledRejection = (window as any).posthogErrorWrappingFunctions.wrapUnhandledRejection
+        const wrapOnError = assignableWindow.__PosthogExtensions__?.errorWrappingFunctions?.wrapOnError
+        const wrapUnhandledRejection =
+            assignableWindow.__PosthogExtensions__?.errorWrappingFunctions?.wrapUnhandledRejection
 
         if (!wrapOnError || !wrapUnhandledRejection) {
             logger.error(LOGGER_PREFIX + ' failed to load error wrapping functions - cannot start')
diff --git a/src/extensions/replay/sessionrecording.ts b/src/extensions/replay/sessionrecording.ts
index c4b592556..aaa94d439 100644
--- a/src/extensions/replay/sessionrecording.ts
+++ b/src/extensions/replay/sessionrecording.ts
@@ -118,7 +118,7 @@ export class SessionRecording {
     _forceAllowLocalhostNetworkCapture = false
 
     private get rrwebRecord(): rrwebRecord | undefined {
-        return assignableWindow?.rrweb?.record
+        return assignableWindow?.__PosthogExtensions__?.rrweb?.record
     }
 
     public get started(): boolean {
@@ -735,18 +735,18 @@ export class SessionRecording {
     private _gatherRRWebPlugins() {
         const plugins: RecordPlugin<unknown>[] = []
 
-        if (assignableWindow.rrwebConsoleRecord && this.isConsoleLogCaptureEnabled) {
-            plugins.push(assignableWindow.rrwebConsoleRecord.getRecordConsolePlugin())
+        const recordConsolePlugin = assignableWindow.__PosthogExtensions__?.rrwebPlugins?.getRecordConsolePlugin
+        if (recordConsolePlugin && this.isConsoleLogCaptureEnabled) {
+            plugins.push(recordConsolePlugin())
         }
 
-        if (this.networkPayloadCapture && isFunction(assignableWindow.getRecordNetworkPlugin)) {
+        const networkPlugin = assignableWindow.__PosthogExtensions__?.rrwebPlugins?.getRecordNetworkPlugin
+        if (this.networkPayloadCapture && isFunction(networkPlugin)) {
             const canRecordNetwork = !isLocalhost() || this._forceAllowLocalhostNetworkCapture
 
             if (canRecordNetwork) {
                 plugins.push(
-                    assignableWindow.getRecordNetworkPlugin(
-                        buildNetworkRequestOptions(this.instance.config, this.networkPayloadCapture)
-                    )
+                    networkPlugin(buildNetworkRequestOptions(this.instance.config, this.networkPayloadCapture))
                 )
             } else {
                 logger.info(LOGGER_PREFIX + ' NetworkCapture not started because we are on localhost.')
diff --git a/src/extensions/tracing-headers.ts b/src/extensions/tracing-headers.ts
index 02c9a05fd..6ed536049 100644
--- a/src/extensions/tracing-headers.ts
+++ b/src/extensions/tracing-headers.ts
@@ -13,7 +13,7 @@ export class TracingHeaders {
     constructor(private readonly instance: PostHog) {}
 
     private _loadScript(cb: () => void): void {
-        if (assignableWindow.postHogTracingHeadersPatchFns) {
+        if (assignableWindow.__PosthogExtensions__?.tracingHeadersPatchFns) {
             // already loaded
             cb()
         }
@@ -40,10 +40,10 @@ export class TracingHeaders {
     private _startCapturing = () => {
         // NB: we can assert sessionManager is present only because we've checked previously
         if (isUndefined(this._restoreXHRPatch)) {
-            assignableWindow.postHogTracingHeadersPatchFns._patchXHR(this.instance.sessionManager!)
+            assignableWindow.__PosthogExtensions__?.tracingHeadersPatchFns?._patchXHR(this.instance.sessionManager!)
         }
         if (isUndefined(this._restoreFetchPatch)) {
-            assignableWindow.postHogTracingHeadersPatchFns._patchFetch(this.instance.sessionManager!)
+            assignableWindow.__PosthogExtensions__?.tracingHeadersPatchFns?._patchFetch(this.instance.sessionManager!)
         }
     }
 }
diff --git a/src/extensions/web-vitals/index.ts b/src/extensions/web-vitals/index.ts
index 622fde5e0..ea5987e38 100644
--- a/src/extensions/web-vitals/index.ts
+++ b/src/extensions/web-vitals/index.ts
@@ -197,7 +197,7 @@ export class WebVitalsAutocapture {
         let onINP: WebVitalsMetricCallback | undefined
 
         const posthogExtensions = assignableWindow.__PosthogExtensions__
-        if (!isUndefined(posthogExtensions)) {
+        if (!isUndefined(posthogExtensions) && !isUndefined(posthogExtensions.postHogWebVitalsCallbacks)) {
             ;({ onLCP, onCLS, onFCP, onINP } = posthogExtensions.postHogWebVitalsCallbacks)
         }
 
diff --git a/src/posthog-core.ts b/src/posthog-core.ts
index aa9dbba86..3dee01b08 100644
--- a/src/posthog-core.ts
+++ b/src/posthog-core.ts
@@ -1822,8 +1822,14 @@ export class PostHog {
 
     /** Capture a caught exception manually */
     captureException(error: Error, additionalProperties?: Properties): void {
-        const properties: Properties = isFunction(assignableWindow.parseErrorAsProperties)
-            ? assignableWindow.parseErrorAsProperties([error.message, undefined, undefined, undefined, error])
+        const properties: Properties = isFunction(assignableWindow.__PosthogExtensions__?.parseErrorAsProperties)
+            ? assignableWindow.__PosthogExtensions__.parseErrorAsProperties([
+                  error.message,
+                  undefined,
+                  undefined,
+                  undefined,
+                  error,
+              ])
             : {
                   $exception_type: error.name,
                   $exception_message: error.message,
diff --git a/src/posthog-surveys.ts b/src/posthog-surveys.ts
index 331d76643..d7a9f0320 100644
--- a/src/posthog-surveys.ts
+++ b/src/posthog-surveys.ts
@@ -74,7 +74,7 @@ export class PostHogSurveys {
     }
 
     loadIfEnabled() {
-        const surveysGenerator = assignableWindow?.extendPostHogWithSurveys
+        const surveysGenerator = assignableWindow?.__PosthogExtensions__?.generateSurveys
 
         if (!this.instance.config.disable_surveys && this._decideServerResponse && !surveysGenerator) {
             if (this._surveyEventReceiver == null) {
@@ -85,7 +85,7 @@ export class PostHogSurveys {
                     return logger.error(LOGGER_PREFIX, 'Could not load surveys script', err)
                 }
 
-                this._surveyManager = assignableWindow.extendPostHogWithSurveys(this.instance)
+                this._surveyManager = assignableWindow.__PosthogExtensions__?.generateSurveys?.(this.instance)
             })
         }
     }
diff --git a/src/utils/globals.ts b/src/utils/globals.ts
index 48472df92..294866c1a 100644
--- a/src/utils/globals.ts
+++ b/src/utils/globals.ts
@@ -1,3 +1,7 @@
+import { SessionIdManager } from '../sessionid'
+import { ErrorEventArgs, ErrorProperties, Properties } from '../types'
+import { PostHog } from '../posthog-core'
+
 /*
  * Global helpers to protect access to browser globals in a way that is safer for different targets
  * like DOM, SSR, Web workers etc.
@@ -11,6 +15,32 @@
 // eslint-disable-next-line no-restricted-globals
 const win: (Window & typeof globalThis) | undefined = typeof window !== 'undefined' ? window : undefined
 
+/**
+ * This is our contract between (potentially) lazily loaded extensions and the SDK
+ * changes to this interface can be breaking changes for users of the SDK
+ */
+interface PosthogExtensions {
+    parseErrorAsProperties?: ([event, source, lineno, colno, error]: ErrorEventArgs) => ErrorProperties
+    errorWrappingFunctions?: {
+        wrapOnError: (captureFn: (props: Properties) => void) => () => void
+        wrapUnhandledRejection: (captureFn: (props: Properties) => void) => () => void
+    }
+    rrweb?: { record: any; version: string; rrwebVersion: string }
+    rrwebPlugins?: { getRecordConsolePlugin: any; getRecordNetworkPlugin?: any }
+    canActivateRepeatedly?: (survey: any) => boolean
+    generateSurveys?: (posthog: PostHog) => any | undefined
+    postHogWebVitalsCallbacks?: {
+        onLCP: (metric: any) => void
+        onCLS: (metric: any) => void
+        onFCP: (metric: any) => void
+        onINP: (metric: any) => void
+    }
+    tracingHeadersPatchFns?: {
+        _patchFetch: (sessionManager: SessionIdManager) => () => void
+        _patchXHR: (sessionManager: any) => () => void
+    }
+}
+
 const global: typeof globalThis | undefined = typeof globalThis !== 'undefined' ? globalThis : win
 
 export const ArrayProto = Array.prototype
@@ -25,6 +55,10 @@ export const XMLHttpRequest =
     global?.XMLHttpRequest && 'withCredentials' in new global.XMLHttpRequest() ? global.XMLHttpRequest : undefined
 export const AbortController = global?.AbortController
 export const userAgent = navigator?.userAgent
-export const assignableWindow: Window & typeof globalThis & Record<string, any> = win ?? ({} as any)
+export const assignableWindow: Window &
+    typeof globalThis &
+    Record<string, any> & {
+        __PosthogExtensions__?: PosthogExtensions
+    } = win ?? ({} as any)
 
 export { win as window }