diff --git a/packages/playwright-core/src/server/dispatchers/dispatcher.ts b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
index cc3820e21f..1b52ab5658 100644
--- a/packages/playwright-core/src/server/dispatchers/dispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
@@ -26,6 +26,7 @@ import { rewriteErrorMessage } from '../../utils/stackTrace';
 import type { PlaywrightDispatcher } from './playwrightDispatcher';
 import { eventsHelper } from '../..//utils/eventsHelper';
 import type { RegisteredListener } from '../..//utils/eventsHelper';
+import type * as trace from '@trace/trace';
 
 export const dispatcherSymbol = Symbol('dispatcher');
 const metadataValidator = createMetadataValidator();
@@ -186,20 +187,15 @@ export class DispatcherConnection {
 
   private _sendMessageToClient(guid: string, type: string, method: string, params: any, sdkObject?: SdkObject) {
     if (sdkObject) {
-      const eventMetadata: CallMetadata = {
-        id: `event@${++lastEventId}`,
-        objectId: sdkObject?.guid,
-        pageId: sdkObject?.attribution?.page?.guid,
-        frameId: sdkObject?.attribution?.frame?.guid,
-        startTime: monotonicTime(),
-        endTime: 0,
-        type,
+      const event: trace.EventTraceEvent = {
+        type: 'event',
+        class: type,
         method,
         params: params || {},
-        log: [],
-        snapshots: []
+        time: monotonicTime(),
+        pageId: sdkObject?.attribution?.page?.guid,
       };
-      sdkObject.instrumentation?.onEvent(sdkObject, eventMetadata);
+      sdkObject.instrumentation?.onEvent(sdkObject, event);
     }
     this.onmessage({ guid, method, params });
   }
@@ -330,5 +326,3 @@ function formatLogRecording(log: string[]): string {
   const rightLength = headerLength - header.length - leftLength;
   return `\n${'='.repeat(leftLength)}${header}${'='.repeat(rightLength)}\n${log.join('\n')}\n${'='.repeat(headerLength)}`;
 }
-
-let lastEventId = 0;
diff --git a/packages/playwright-core/src/server/instrumentation.ts b/packages/playwright-core/src/server/instrumentation.ts
index f8d22390ae..8f06a7afcd 100644
--- a/packages/playwright-core/src/server/instrumentation.ts
+++ b/packages/playwright-core/src/server/instrumentation.ts
@@ -35,6 +35,7 @@ export type Attribution = {
 
 import type { CallMetadata } from '@protocol/callMetadata';
 export type { CallMetadata } from '@protocol/callMetadata';
+import type * as trace from '@trace/trace';
 
 export const kTestSdkObjects = new WeakSet<SdkObject>();
 
@@ -61,7 +62,7 @@ export interface Instrumentation {
   onBeforeInputAction(sdkObject: SdkObject, metadata: CallMetadata, element: ElementHandle): Promise<void>;
   onCallLog(sdkObject: SdkObject, metadata: CallMetadata, logName: string, message: string): void;
   onAfterCall(sdkObject: SdkObject, metadata: CallMetadata): Promise<void>;
-  onEvent(sdkObject: SdkObject, metadata: CallMetadata): void;
+  onEvent(sdkObject: SdkObject, event: trace.EventTraceEvent): void;
   onPageOpen(page: Page): void;
   onPageClose(page: Page): void;
   onBrowserOpen(browser: Browser): void;
@@ -73,7 +74,7 @@ export interface InstrumentationListener {
   onBeforeInputAction?(sdkObject: SdkObject, metadata: CallMetadata, element: ElementHandle): Promise<void>;
   onCallLog?(sdkObject: SdkObject, metadata: CallMetadata, logName: string, message: string): void;
   onAfterCall?(sdkObject: SdkObject, metadata: CallMetadata): Promise<void>;
-  onEvent?(sdkObject: SdkObject, metadata: CallMetadata): void;
+  onEvent?(sdkObject: SdkObject, event: trace.EventTraceEvent): void;
   onPageOpen?(page: Page): void;
   onPageClose?(page: Page): void;
   onBrowserOpen?(browser: Browser): void;
diff --git a/packages/playwright-core/src/server/trace/recorder/tracing.ts b/packages/playwright-core/src/server/trace/recorder/tracing.ts
index 730e45ef0f..5d7195bb24 100644
--- a/packages/playwright-core/src/server/trace/recorder/tracing.ts
+++ b/packages/playwright-core/src/server/trace/recorder/tracing.ts
@@ -43,7 +43,7 @@ import type { SnapshotterBlob, SnapshotterDelegate } from './snapshotter';
 import { Snapshotter } from './snapshotter';
 import { yazl } from '../../../zipBundle';
 
-const version: VERSION = 3;
+const version: VERSION = 4;
 
 export type TracerOptions = {
   name?: string;
@@ -341,15 +341,25 @@ export class Tracing extends SdkObject implements InstrumentationListener, Snaps
     }
     pendingCall.afterSnapshot = this._captureSnapshot('after', sdkObject, metadata);
     await pendingCall.afterSnapshot;
-    const event: trace.ActionTraceEvent = { type: 'action', metadata };
-    this._appendTraceEvent(event);
+    const event = createActionTraceEvent(metadata);
+    if (event)
+      this._appendTraceEvent(event);
     this._pendingCalls.delete(metadata.id);
   }
 
-  onEvent(sdkObject: SdkObject, metadata: CallMetadata) {
+  onEvent(sdkObject: SdkObject, event: trace.EventTraceEvent) {
     if (!sdkObject.attribution.context)
       return;
-    const event: trace.ActionTraceEvent = { type: 'event', metadata };
+    if (event.method === '__create__' && event.class === 'ConsoleMessage') {
+      const object: trace.ObjectTraceEvent = {
+        type: 'object',
+        class: event.class,
+        guid: event.params.guid,
+        initializer: event.params.initializer,
+      };
+      this._appendTraceEvent(object);
+      return;
+    }
     this._appendTraceEvent(event);
   }
 
@@ -467,3 +477,25 @@ function visitTraceEvent(object: any, sha1s: Set<string>): any {
 export function shouldCaptureSnapshot(metadata: CallMetadata): boolean {
   return commandsWithTracingSnapshots.has(metadata.type + '.' + metadata.method);
 }
+
+function createActionTraceEvent(metadata: CallMetadata): trace.ActionTraceEvent | null {
+  if (metadata.internal || metadata.method.startsWith('tracing'))
+    return null;
+  return {
+    type: 'action',
+    callId: metadata.id,
+    startTime: metadata.startTime,
+    endTime: metadata.endTime,
+    apiName: metadata.apiName || metadata.type + '.' + metadata.method,
+    class: metadata.type,
+    method: metadata.method,
+    params: metadata.params,
+    wallTime: metadata.wallTime || Date.now(),
+    log: metadata.log,
+    snapshots: metadata.snapshots,
+    error: metadata.error?.error,
+    result: metadata.result,
+    point: metadata.point,
+    pageId: metadata.pageId,
+  };
+}
diff --git a/packages/trace-viewer/src/entries.ts b/packages/trace-viewer/src/entries.ts
index 2b9670d306..c55b4171b7 100644
--- a/packages/trace-viewer/src/entries.ts
+++ b/packages/trace-viewer/src/entries.ts
@@ -32,8 +32,8 @@ export type ContextEntry = {
   pages: PageEntry[];
   resources: ResourceSnapshot[];
   actions: trace.ActionTraceEvent[];
-  events: trace.ActionTraceEvent[];
-  objects: { [key: string]: any };
+  events: trace.EventTraceEvent[];
+  initializers: { [key: string]: any };
   hasSource: boolean;
 };
 
@@ -60,7 +60,7 @@ export function createEmptyContext(): ContextEntry {
     resources: [],
     actions: [],
     events: [],
-    objects: {},
+    initializers: {},
     hasSource: false
   };
 }
diff --git a/packages/trace-viewer/src/traceModel.ts b/packages/trace-viewer/src/traceModel.ts
index 7995450202..baef807ef1 100644
--- a/packages/trace-viewer/src/traceModel.ts
+++ b/packages/trace-viewer/src/traceModel.ts
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-import type { CallMetadata } from '@protocol/callMetadata';
 import type * as trace from '@trace/trace';
+import type * as traceV3 from './versions/traceV3';
 import { parseClientSideCallMetadata } from '@trace/traceUtils';
 import type zip from '@zip.js/zip.js';
 // @ts-ignore
@@ -87,7 +87,7 @@ export class TraceModel {
       await stacksEntry.getData!(writer);
       const metadataMap = parseClientSideCallMetadata(JSON.parse(await writer.getData()));
       for (const action of this.contextEntry.actions)
-        action.metadata.stack = action.metadata.stack || metadataMap.get(action.metadata.id);
+        action.stack = action.stack || metadataMap.get(action.callId);
     }
 
     this._build();
@@ -117,7 +117,7 @@ export class TraceModel {
   }
 
   private _build() {
-    this.contextEntry!.actions.sort((a1, a2) => a1.metadata.startTime - a2.metadata.startTime);
+    this.contextEntry!.actions.sort((a1, a2) => a1.startTime - a2.startTime);
     this.contextEntry!.resources = this._snapshotStorage!.resources();
   }
 
@@ -137,6 +137,8 @@ export class TraceModel {
     if (!line)
       return;
     const event = this._modernize(JSON.parse(line));
+    if (!event)
+      return;
     switch (event.type) {
       case 'context-options': {
         this.contextEntry.browserName = event.browserName;
@@ -153,22 +155,15 @@ export class TraceModel {
         break;
       }
       case 'action': {
-        const include = !isTracing(event.metadata) && (!event.metadata.internal || event.metadata.apiName);
-        if (include) {
-          if (!event.metadata.apiName)
-            event.metadata.apiName = event.metadata.type + '.' + event.metadata.method;
-          this.contextEntry!.actions.push(event);
-        }
+        this.contextEntry!.actions.push(event);
         break;
       }
       case 'event': {
-        const metadata = event.metadata;
-        if (metadata.pageId) {
-          if (metadata.method === '__create__')
-            this.contextEntry!.objects[metadata.params.guid] = metadata.params.initializer;
-          else
-            this.contextEntry!.events.push(event);
-        }
+        this.contextEntry!.events.push(event);
+        break;
+      }
+      case 'object': {
+        this.contextEntry!.initializers[event.guid] = event.initializer;
         break;
       }
       case 'resource-snapshot':
@@ -178,9 +173,13 @@ export class TraceModel {
         this._snapshotStorage!.addFrameSnapshot(event.snapshot);
         break;
     }
-    if (event.type === 'action' || event.type === 'event') {
-      this.contextEntry!.startTime = Math.min(this.contextEntry!.startTime, event.metadata.startTime);
-      this.contextEntry!.endTime = Math.max(this.contextEntry!.endTime, event.metadata.endTime);
+    if (event.type === 'action') {
+      this.contextEntry!.startTime = Math.min(this.contextEntry!.startTime, event.startTime);
+      this.contextEntry!.endTime = Math.max(this.contextEntry!.endTime, event.endTime);
+    }
+    if (event.type === 'event') {
+      this.contextEntry!.startTime = Math.min(this.contextEntry!.startTime, event.time);
+      this.contextEntry!.endTime = Math.max(this.contextEntry!.endTime, event.time);
     }
     if (event.type === 'screencast-frame') {
       this.contextEntry!.startTime = Math.min(this.contextEntry!.startTime, event.timestamp);
@@ -237,6 +236,54 @@ export class TraceModel {
     }
     return event;
   }
+
+  _modernize_3_to_4(event: traceV3.TraceEvent): trace.TraceEvent | null {
+    if (event.type !== 'action') {
+      return event as traceV3.ContextCreatedTraceEvent |
+        traceV3.ScreencastFrameTraceEvent |
+        traceV3.ResourceSnapshotTraceEvent |
+        traceV3.FrameSnapshotTraceEvent;
+    }
+
+    const metadata = event.metadata;
+    if (metadata.internal || metadata.method.startsWith('tracing'))
+      return null;
+    if (metadata.id.startsWith('event@')) {
+      if (metadata.method === '__create__' && metadata.type === 'ConsoleMessage') {
+        return {
+          type: 'object',
+          class: metadata.type,
+          guid: metadata.params.guid,
+          initializer: metadata.params.initializer,
+        };
+      }
+      return {
+        type: 'event',
+        time: metadata.startTime,
+        class: metadata.type,
+        method: metadata.method,
+        params: metadata.params,
+        pageId: metadata.pageId,
+      };
+    }
+    return {
+      type: 'action',
+      callId: metadata.id,
+      startTime: metadata.startTime,
+      endTime: metadata.endTime,
+      apiName: metadata.apiName || metadata.type + '.' + metadata.method,
+      class: metadata.type,
+      method: metadata.method,
+      params: metadata.params,
+      wallTime: metadata.wallTime || Date.now(),
+      log: metadata.log,
+      snapshots: metadata.snapshots,
+      error: metadata.error?.error,
+      result: metadata.result,
+      point: metadata.point,
+      pageId: metadata.pageId,
+    };
+  }
 }
 
 export class PersistentSnapshotStorage extends BaseSnapshotStorage {
@@ -254,7 +301,3 @@ export class PersistentSnapshotStorage extends BaseSnapshotStorage {
     return writer.getData();
   }
 }
-
-function isTracing(metadata: CallMetadata): boolean {
-  return metadata.method.startsWith('tracing');
-}
diff --git a/packages/trace-viewer/src/ui/actionList.tsx b/packages/trace-viewer/src/ui/actionList.tsx
index 94989648e5..4fb935f062 100644
--- a/packages/trace-viewer/src/ui/actionList.tsx
+++ b/packages/trace-viewer/src/ui/actionList.tsx
@@ -45,8 +45,8 @@ export const ActionList: React.FC<ActionListProps> = ({
     selectedItem={selectedAction}
     onSelected={(action: ActionTraceEvent) => onSelected(action)}
     onHighlighted={(action: ActionTraceEvent) => onHighlighted(action)}
-    itemKey={(action: ActionTraceEvent) => action.metadata.id}
-    itemType={(action: ActionTraceEvent) => action.metadata.error?.error?.message ? 'error' : undefined}
+    itemKey={(action: ActionTraceEvent) => action.callId}
+    itemType={(action: ActionTraceEvent) => action.error?.message ? 'error' : undefined}
     itemRender={(action: ActionTraceEvent) => renderAction(action, sdkLanguage, setSelectedTab)}
     showNoItemsMessage={true}
   ></ListView>;
@@ -57,17 +57,16 @@ const renderAction = (
   sdkLanguage: Language | undefined,
   setSelectedTab: (tab: string) => void
 ) => {
-  const { metadata } = action;
   const { errors, warnings } = modelUtil.stats(action);
-  const locator = metadata.params.selector ? asLocator(sdkLanguage || 'javascript', metadata.params.selector) : undefined;
+  const locator = action.params.selector ? asLocator(sdkLanguage || 'javascript', action.params.selector) : undefined;
 
   return <>
     <div className='action-title'>
-      <span>{metadata.apiName}</span>
+      <span>{action.apiName}</span>
       {locator && <div className='action-selector' title={locator}>{locator}</div>}
-      {metadata.method === 'goto' && metadata.params.url && <div className='action-url' title={metadata.params.url}>{metadata.params.url}</div>}
+      {action.method === 'goto' && action.params.url && <div className='action-url' title={action.params.url}>{action.params.url}</div>}
     </div>
-    <div className='action-duration' style={{ flex: 'none' }}>{metadata.endTime ? msToString(metadata.endTime - metadata.startTime) : 'Timed Out'}</div>
+    <div className='action-duration' style={{ flex: 'none' }}>{action.endTime ? msToString(action.endTime - action.startTime) : 'Timed Out'}</div>
     <div className='action-icons' onClick={() => setSelectedTab('console')}>
       {!!errors && <div className='action-icon'><span className={'codicon codicon-error'}></span><span className="action-icon-value">{errors}</span></div>}
       {!!warnings && <div className='action-icon'><span className={'codicon codicon-warning'}></span><span className="action-icon-value">{warnings}</span></div>}
diff --git a/packages/trace-viewer/src/ui/callTab.tsx b/packages/trace-viewer/src/ui/callTab.tsx
index 58874f8bab..8593d48779 100644
--- a/packages/trace-viewer/src/ui/callTab.tsx
+++ b/packages/trace-viewer/src/ui/callTab.tsx
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-import type { CallMetadata } from '@protocol/callMetadata';
 import type { SerializedValue } from '@protocol/channels';
 import type { ActionTraceEvent } from '@trace/trace';
 import { msToString } from '@web/uiUtils';
@@ -30,20 +29,20 @@ export const CallTab: React.FunctionComponent<{
 }> = ({ action, sdkLanguage }) => {
   if (!action)
     return null;
-  const logs = action.metadata.log;
-  const error = action.metadata.error?.error?.message;
-  const params = { ...action.metadata.params };
+  const logs = action.log;
+  const error = action.error?.message;
+  const params = { ...action.params };
   // Strip down the waitForEventInfo data, we never need it.
   delete params.info;
   const paramKeys = Object.keys(params);
-  const wallTime = action.metadata.wallTime ? new Date(action.metadata.wallTime).toLocaleString() : null;
-  const duration = action.metadata.endTime ? msToString(action.metadata.endTime - action.metadata.startTime) : 'Timed Out';
+  const wallTime = action.wallTime ? new Date(action.wallTime).toLocaleString() : null;
+  const duration = action.endTime ? msToString(action.endTime - action.startTime) : 'Timed Out';
   return <div className='call-tab'>
     <div className='call-error' key='error' hidden={!error}>
       <div className='codicon codicon-issues'/>
       {error}
     </div>
-    <div className='call-line'>{action.metadata.apiName}</div>
+    <div className='call-line'>{action.apiName}</div>
     {<>
       <div className='call-section'>Time</div>
       {wallTime && <div className='call-line'>wall time:<span className='call-value datetime' title={wallTime}>{wallTime}</span></div>}
@@ -51,12 +50,12 @@ export const CallTab: React.FunctionComponent<{
     </>}
     { !!paramKeys.length && <div className='call-section'>Parameters</div> }
     {
-      !!paramKeys.length && paramKeys.map((name, index) => renderProperty(propertyToString(action.metadata, name, params[name], sdkLanguage), 'param-' + index))
+      !!paramKeys.length && paramKeys.map((name, index) => renderProperty(propertyToString(action, name, params[name], sdkLanguage), 'param-' + index))
     }
-    { !!action.metadata.result && <div className='call-section'>Return value</div> }
+    { !!action.result && <div className='call-section'>Return value</div> }
     {
-      !!action.metadata.result && Object.keys(action.metadata.result).map((name, index) =>
-        renderProperty(propertyToString(action.metadata, name, action.metadata.result[name], sdkLanguage), 'result-' + index)
+      !!action.result && Object.keys(action.result).map((name, index) =>
+        renderProperty(propertyToString(action, name, action.result[name], sdkLanguage), 'result-' + index)
       )
     }
     <div className='call-section'>Log</div>
@@ -90,14 +89,14 @@ function renderProperty(property: Property, key: string) {
   );
 }
 
-function propertyToString(metadata: CallMetadata, name: string, value: any, sdkLanguage: Language | undefined): Property {
-  const isEval = metadata.method.includes('eval') || metadata.method === 'waitForFunction';
+function propertyToString(event: ActionTraceEvent, name: string, value: any, sdkLanguage: Language | undefined): Property {
+  const isEval = event.method.includes('eval') || event.method === 'waitForFunction';
   if (name === 'eventInit' || name === 'expectedValue' || (name === 'arg' && isEval))
     value = parseSerializedValue(value.value, new Array(10).fill({ handle: '<handle>' }));
-  if ((name === 'value' && isEval) || (name === 'received' && metadata.method === 'expect'))
+  if ((name === 'value' && isEval) || (name === 'received' && event.method === 'expect'))
     value = parseSerializedValue(value, new Array(10).fill({ handle: '<handle>' }));
   if (name === 'selector')
-    return { text: asLocator(sdkLanguage || 'javascript', metadata.params.selector), type: 'locator', name: 'locator' };
+    return { text: asLocator(sdkLanguage || 'javascript', event.params.selector), type: 'locator', name: 'locator' };
   const type = typeof value;
   if (type !== 'object' || value === null)
     return { text: String(value), type, name };
diff --git a/packages/trace-viewer/src/ui/consoleTab.tsx b/packages/trace-viewer/src/ui/consoleTab.tsx
index 5f7c0210f2..cb9470e63f 100644
--- a/packages/trace-viewer/src/ui/consoleTab.tsx
+++ b/packages/trace-viewer/src/ui/consoleTab.tsx
@@ -29,14 +29,14 @@ export const ConsoleTab: React.FunctionComponent<{
     const entries: { message?: channels.ConsoleMessageInitializer, error?: channels.SerializedError }[] = [];
     const context = modelUtil.context(action);
     for (const event of modelUtil.eventsForAction(action)) {
-      if (event.metadata.method !== 'console' && event.metadata.method !== 'pageError')
+      if (event.method !== 'console' && event.method !== 'pageError')
         continue;
-      if (event.metadata.method === 'console') {
-        const { guid } = event.metadata.params.message;
-        entries.push({ message: context.objects[guid] });
+      if (event.method === 'console') {
+        const { guid } = event.params.message;
+        entries.push({ message: context.initializers[guid] });
       }
-      if (event.metadata.method === 'pageError')
-        entries.push({ error: event.metadata.params.error });
+      if (event.method === 'pageError')
+        entries.push({ error: event.params.error });
     }
     return entries;
   }, [action]);
diff --git a/packages/trace-viewer/src/ui/modelUtil.ts b/packages/trace-viewer/src/ui/modelUtil.ts
index 71848a3024..b87b72aa3c 100644
--- a/packages/trace-viewer/src/ui/modelUtil.ts
+++ b/packages/trace-viewer/src/ui/modelUtil.ts
@@ -17,7 +17,7 @@
 import type { Language } from '@isomorphic/locatorGenerators';
 import type { ResourceSnapshot } from '@trace/snapshot';
 import type * as trace from '@trace/trace';
-import type { ActionTraceEvent } from '@trace/trace';
+import type { ActionTraceEvent, EventTraceEvent } from '@trace/trace';
 import type { ContextEntry, PageEntry } from '../entries';
 
 const contextSymbol = Symbol('context');
@@ -35,7 +35,7 @@ export class MultiTraceModel {
   readonly options: trace.BrowserContextEventOptions;
   readonly pages: PageEntry[];
   readonly actions: trace.ActionTraceEvent[];
-  readonly events: trace.ActionTraceEvent[];
+  readonly events: trace.EventTraceEvent[];
   readonly hasSource: boolean;
   readonly sdkLanguage: Language | undefined;
   readonly testIdAttributeName: string | undefined;
@@ -54,11 +54,11 @@ export class MultiTraceModel {
     this.endTime = contexts.map(c => c.endTime).reduce((prev, cur) => Math.max(prev, cur), Number.MIN_VALUE);
     this.pages = ([] as PageEntry[]).concat(...contexts.map(c => c.pages));
     this.actions = ([] as ActionTraceEvent[]).concat(...contexts.map(c => c.actions));
-    this.events = ([] as ActionTraceEvent[]).concat(...contexts.map(c => c.events));
+    this.events = ([] as EventTraceEvent[]).concat(...contexts.map(c => c.events));
     this.hasSource = contexts.some(c => c.hasSource);
 
-    this.actions.sort((a1, a2) => a1.metadata.startTime - a2.metadata.startTime);
-    this.events.sort((a1, a2) => a1.metadata.startTime - a2.metadata.startTime);
+    this.actions.sort((a1, a2) => a1.startTime - a2.startTime);
+    this.events.sort((a1, a2) => a1.time - a2.time);
   }
 }
 
@@ -87,28 +87,28 @@ export function stats(action: ActionTraceEvent): { errors: number, warnings: num
   let warnings = 0;
   const c = context(action);
   for (const event of eventsForAction(action)) {
-    if (event.metadata.method === 'console') {
-      const { guid } = event.metadata.params.message;
-      const type = c.objects[guid]?.type;
+    if (event.method === 'console') {
+      const { guid } = event.params.message;
+      const type = c.initializers[guid]?.type;
       if (type === 'warning')
         ++warnings;
       else if (type === 'error')
         ++errors;
     }
-    if (event.metadata.method === 'pageError')
+    if (event.method === 'pageError')
       ++errors;
   }
   return { errors, warnings };
 }
 
-export function eventsForAction(action: ActionTraceEvent): ActionTraceEvent[] {
-  let result: ActionTraceEvent[] = (action as any)[eventsSymbol];
+export function eventsForAction(action: ActionTraceEvent): EventTraceEvent[] {
+  let result: EventTraceEvent[] = (action as any)[eventsSymbol];
   if (result)
     return result;
 
   const nextAction = next(action);
   result = context(action).events.filter(event => {
-    return event.metadata.startTime >= action.metadata.startTime && (!nextAction || event.metadata.startTime < nextAction.metadata.startTime);
+    return event.time >= action.startTime && (!nextAction || event.time < nextAction.startTime);
   });
   (action as any)[eventsSymbol] = result;
   return result;
@@ -121,7 +121,7 @@ export function resourcesForAction(action: ActionTraceEvent): ResourceSnapshot[]
 
   const nextAction = next(action);
   result = context(action).resources.filter(resource => {
-    return typeof resource._monotonicTime === 'number' && resource._monotonicTime > action.metadata.startTime && (!nextAction || resource._monotonicTime < nextAction.metadata.startTime);
+    return typeof resource._monotonicTime === 'number' && resource._monotonicTime > action.startTime && (!nextAction || resource._monotonicTime < nextAction.startTime);
   });
   (action as any)[resourcesSymbol] = result;
   return result;
diff --git a/packages/trace-viewer/src/ui/snapshotTab.tsx b/packages/trace-viewer/src/ui/snapshotTab.tsx
index fba0c01a65..9aaa4d50ad 100644
--- a/packages/trace-viewer/src/ui/snapshotTab.tsx
+++ b/packages/trace-viewer/src/ui/snapshotTab.tsx
@@ -42,7 +42,7 @@ export const SnapshotTab: React.FunctionComponent<{
   const [pickerVisible, setPickerVisible] = React.useState(false);
 
   const snapshotMap = new Map<string, { title: string, snapshotName: string }>();
-  for (const snapshot of action?.metadata.snapshots || [])
+  for (const snapshot of action?.snapshots || [])
     snapshotMap.set(snapshot.title, snapshot);
   const actionSnapshot = snapshotMap.get('action') || snapshotMap.get('after');
   const snapshots = [actionSnapshot ? { ...actionSnapshot, title: 'action' } : undefined, snapshotMap.get('before'), snapshotMap.get('after')].filter(Boolean) as { title: string, snapshotName: string }[];
@@ -58,11 +58,11 @@ export const SnapshotTab: React.FunctionComponent<{
       const params = new URLSearchParams();
       params.set('trace', context(action).traceUrl);
       params.set('name', snapshot.snapshotName);
-      snapshotUrl = new URL(`snapshot/${action.metadata.pageId}?${params.toString()}`, window.location.href).toString();
-      snapshotInfoUrl = new URL(`snapshotInfo/${action.metadata.pageId}?${params.toString()}`, window.location.href).toString();
+      snapshotUrl = new URL(`snapshot/${action.pageId}?${params.toString()}`, window.location.href).toString();
+      snapshotInfoUrl = new URL(`snapshotInfo/${action.pageId}?${params.toString()}`, window.location.href).toString();
       if (snapshot.snapshotName.includes('action')) {
-        pointX = action.metadata.point?.x;
-        pointY = action.metadata.point?.y;
+        pointX = action.point?.x;
+        pointY = action.point?.y;
       }
       const popoutParams = new URLSearchParams();
       popoutParams.set('r', snapshotUrl);
diff --git a/packages/trace-viewer/src/ui/sourceTab.tsx b/packages/trace-viewer/src/ui/sourceTab.tsx
index e33018f219..901a59a2c8 100644
--- a/packages/trace-viewer/src/ui/sourceTab.tsx
+++ b/packages/trace-viewer/src/ui/sourceTab.tsx
@@ -44,10 +44,7 @@ export const SourceTab: React.FunctionComponent<{
   const stackInfo = React.useMemo<StackInfo>(() => {
     if (!action)
       return '';
-    const { metadata } = action;
-    if (!metadata.stack)
-      return '';
-    const frames = metadata.stack;
+    const frames = action.stack || [];
     return {
       frames,
       fileContent: new Map(),
diff --git a/packages/trace-viewer/src/ui/stackTrace.tsx b/packages/trace-viewer/src/ui/stackTrace.tsx
index fbf175b505..ffcc97bcd6 100644
--- a/packages/trace-viewer/src/ui/stackTrace.tsx
+++ b/packages/trace-viewer/src/ui/stackTrace.tsx
@@ -24,7 +24,7 @@ export const StackTraceView: React.FunctionComponent<{
   selectedFrame: number,
   setSelectedFrame: (index: number) => void
 }> = ({ action, setSelectedFrame, selectedFrame }) => {
-  const frames = action?.metadata.stack || [];
+  const frames = action?.stack || [];
   return <ListView
     dataTestId='stack-trace'
     items={frames}
diff --git a/packages/trace-viewer/src/ui/timeline.tsx b/packages/trace-viewer/src/ui/timeline.tsx
index 6505bd7885..90a40e6657 100644
--- a/packages/trace-viewer/src/ui/timeline.tsx
+++ b/packages/trace-viewer/src/ui/timeline.tsx
@@ -15,7 +15,7 @@
   limitations under the License.
 */
 
-import type { ActionTraceEvent } from '@trace/trace';
+import type { ActionTraceEvent, EventTraceEvent } from '@trace/trace';
 import { msToString } from '@web/uiUtils';
 import * as React from 'react';
 import type { Boundaries } from '../geometry';
@@ -26,7 +26,7 @@ import './timeline.css';
 
 type TimelineBar = {
   action?: ActionTraceEvent;
-  event?: ActionTraceEvent;
+  event?: EventTraceEvent;
   leftPosition: number;
   rightPosition: number;
   leftTime: number;
@@ -56,34 +56,34 @@ export const Timeline: React.FunctionComponent<{
   const bars = React.useMemo(() => {
     const bars: TimelineBar[] = [];
     for (const entry of context.actions) {
-      let detail = trimRight(entry.metadata.params.selector || '', 50);
-      if (entry.metadata.method === 'goto')
-        detail = trimRight(entry.metadata.params.url || '', 50);
+      let detail = trimRight(entry.params.selector || '', 50);
+      if (entry.method === 'goto')
+        detail = trimRight(entry.params.url || '', 50);
       bars.push({
         action: entry,
-        leftTime: entry.metadata.startTime,
-        rightTime: entry.metadata.endTime,
-        leftPosition: timeToPosition(measure.width, boundaries, entry.metadata.startTime),
-        rightPosition: timeToPosition(measure.width, boundaries, entry.metadata.endTime),
-        label: entry.metadata.apiName + ' ' + detail,
-        title: entry.metadata.endTime ? msToString(entry.metadata.endTime - entry.metadata.startTime) : 'Timed Out',
-        type: entry.metadata.type + '.' + entry.metadata.method,
-        className: `${entry.metadata.type}_${entry.metadata.method}`.toLowerCase()
+        leftTime: entry.startTime,
+        rightTime: entry.endTime,
+        leftPosition: timeToPosition(measure.width, boundaries, entry.startTime),
+        rightPosition: timeToPosition(measure.width, boundaries, entry.endTime),
+        label: entry.apiName + ' ' + detail,
+        title: entry.endTime ? msToString(entry.endTime - entry.startTime) : 'Timed Out',
+        type: entry.type + '.' + entry.method,
+        className: `${entry.type}_${entry.method}`.toLowerCase()
       });
     }
 
     for (const event of context.events) {
-      const startTime = event.metadata.startTime;
+      const startTime = event.time;
       bars.push({
         event,
         leftTime: startTime,
         rightTime: startTime,
         leftPosition: timeToPosition(measure.width, boundaries, startTime),
         rightPosition: timeToPosition(measure.width, boundaries, startTime),
-        label: event.metadata.method,
-        title: event.metadata.endTime ? msToString(event.metadata.endTime - event.metadata.startTime) : 'Timed Out',
-        type: event.metadata.type + '.' + event.metadata.method,
-        className: `${event.metadata.type}_${event.metadata.method}`.toLowerCase()
+        label: event.method,
+        title: '0',
+        type: event.class + '.' + event.method,
+        className: `${event.class}_${event.method}`.toLowerCase()
       });
     }
     return bars;
@@ -237,5 +237,5 @@ function trimRight(s: string, maxLength: number): string {
 
 const kBarHeight = 11;
 function barTop(bar: TimelineBar): number {
-  return bar.event ? 22 : (bar.action?.metadata.method === 'waitForEventInfo' ? 0 : 11);
+  return bar.event ? 22 : (bar.action?.method === 'waitForEventInfo' ? 0 : 11);
 }
diff --git a/packages/trace-viewer/src/versions/traceV3.ts b/packages/trace-viewer/src/versions/traceV3.ts
new file mode 100644
index 0000000000..87bc658d9e
--- /dev/null
+++ b/packages/trace-viewer/src/versions/traceV3.ts
@@ -0,0 +1,162 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import type { Entry as ResourceSnapshot } from '../../../trace/src/har';
+
+type SerializedValue = {
+  n?: number,
+  b?: boolean,
+  s?: string,
+  v?: 'null' | 'undefined' | 'NaN' | 'Infinity' | '-Infinity' | '-0',
+  d?: string,
+  u?: string,
+  r?: {
+    p: string,
+    f: string,
+  },
+  a?: SerializedValue[],
+  o?: {
+    k: string,
+    v: SerializedValue,
+  }[],
+  h?: number,
+  id?: number,
+  ref?: number,
+};
+
+type Point = {
+  x: number,
+  y: number,
+};
+
+type StackFrame = {
+  file: string,
+  line: number,
+  column: number,
+  function?: string,
+};
+
+type SerializedError = {
+  error?: {
+    message: string,
+    name: string,
+    stack?: string,
+  },
+  value?: SerializedValue,
+};
+
+type CallMetadata = {
+  id: string;
+  startTime: number;
+  endTime: number;
+  pauseStartTime?: number;
+  pauseEndTime?: number;
+  type: string;
+  method: string;
+  params: any;
+  apiName?: string;
+  internal?: boolean;
+  isServerSide?: boolean;
+  wallTime?: number;
+  location?: { file: string, line?: number, column?: number };
+  log: string[];
+  afterSnapshot?: string;
+  snapshots: { title: string, snapshotName: string }[];
+  error?: SerializedError;
+  result?: any;
+  point?: Point;
+  objectId?: string;
+  pageId?: string;
+  frameId?: string;
+};
+
+export type NodeSnapshot =
+  string |
+  [ [number, number] ] |
+  [ string ] |
+  [ string, { [attr: string]: string }, ...any ];
+
+
+export type ResourceOverride = {
+  url: string,
+  sha1?: string,
+  ref?: number
+};
+
+export type FrameSnapshot = {
+  snapshotName?: string,
+  pageId: string,
+  frameId: string,
+  frameUrl: string,
+  timestamp: number,
+  collectionTime: number,
+  doctype?: string,
+  html: NodeSnapshot,
+  resourceOverrides: ResourceOverride[],
+  viewport: { width: number, height: number },
+  isMainFrame: boolean,
+};
+
+
+export type BrowserContextEventOptions = {
+  viewport?: { width: number, height: number },
+  deviceScaleFactor?: number,
+  isMobile?: boolean,
+  userAgent?: string,
+};
+
+export type ContextCreatedTraceEvent = {
+  version: number,
+  type: 'context-options',
+  browserName: string,
+  platform: string,
+  wallTime: number,
+  title?: string,
+  options: BrowserContextEventOptions,
+  sdkLanguage?: 'javascript' | 'python' | 'java' | 'csharp',
+  testIdAttributeName?: string,
+};
+
+export type ScreencastFrameTraceEvent = {
+  type: 'screencast-frame',
+  pageId: string,
+  sha1: string,
+  width: number,
+  height: number,
+  timestamp: number,
+};
+
+export type ActionTraceEvent = {
+  type: 'action' | 'event',
+  metadata: CallMetadata & { stack?: StackFrame[] },
+};
+
+export type ResourceSnapshotTraceEvent = {
+  type: 'resource-snapshot',
+  snapshot: ResourceSnapshot,
+};
+
+export type FrameSnapshotTraceEvent = {
+  type: 'frame-snapshot',
+  snapshot: FrameSnapshot,
+};
+
+export type TraceEvent =
+    ContextCreatedTraceEvent |
+    ScreencastFrameTraceEvent |
+    ActionTraceEvent |
+    ResourceSnapshotTraceEvent |
+    FrameSnapshotTraceEvent;
diff --git a/packages/trace/src/trace.ts b/packages/trace/src/trace.ts
index e1e5dcb253..6940e25633 100644
--- a/packages/trace/src/trace.ts
+++ b/packages/trace/src/trace.ts
@@ -14,15 +14,14 @@
  * limitations under the License.
  */
 
-import type { CallMetadata } from '@protocol/callMetadata';
-import type { StackFrame } from '@protocol/channels';
+import type { Point, SerializedError, StackFrame } from '@protocol/channels';
 import type { Language } from '../../playwright-core/src/server/isomorphic/locatorGenerators';
 import type { FrameSnapshot, ResourceSnapshot } from './snapshot';
 
 export type Size = { width: number, height: number };
 
 // Make sure you add _modernize_N_to_N1(event: any) to traceModel.ts.
-export type VERSION = 3;
+export type VERSION = 4;
 
 export type BrowserContextEventOptions = {
   viewport?: Size,
@@ -53,8 +52,38 @@ export type ScreencastFrameTraceEvent = {
 };
 
 export type ActionTraceEvent = {
-  type: 'action' | 'event',
-  metadata: CallMetadata & { stack?: StackFrame[] },
+  type: 'action',
+  callId: string;
+  startTime: number;
+  endTime: number;
+  apiName: string;
+  class: string;
+  method: string;
+  params: any;
+  wallTime: number;
+  log: string[];
+  snapshots: { title: string, snapshotName: string }[];
+  stack?: StackFrame[];
+  error?: SerializedError['error'];
+  result?: any;
+  point?: Point;
+  pageId?: string;
+};
+
+export type EventTraceEvent = {
+  type: 'event',
+  time: number;
+  class: string;
+  method: string;
+  params: any;
+  pageId?: string;
+};
+
+export type ObjectTraceEvent = {
+  type: 'object';
+  class: string;
+  initializer: any;
+  guid: string;
 };
 
 export type ResourceSnapshotTraceEvent = {
@@ -71,5 +100,7 @@ export type TraceEvent =
     ContextCreatedTraceEvent |
     ScreencastFrameTraceEvent |
     ActionTraceEvent |
+    EventTraceEvent |
+    ObjectTraceEvent |
     ResourceSnapshotTraceEvent |
     FrameSnapshotTraceEvent;
diff --git a/tests/config/utils.ts b/tests/config/utils.ts
index 1526dd2dbe..dda5dd8d34 100644
--- a/tests/config/utils.ts
+++ b/tests/config/utils.ts
@@ -18,6 +18,7 @@ import type { Frame, Page } from 'playwright-core';
 import { ZipFile } from '../../packages/playwright-core/lib/utils/zipFile';
 import type { StackFrame } from '@protocol/channels';
 import { parseClientSideCallMetadata } from '../../packages/trace/src/traceUtils';
+import type { ActionTraceEvent } from '../../packages/trace/src/trace';
 
 export async function attachFrame(page: Page, frameId: string, url: string): Promise<Frame> {
   const handle = await page.evaluateHandle(async ({ frameId, url }) => {
@@ -28,20 +29,20 @@ export async function attachFrame(page: Page, frameId: string, url: string): Pro
     await new Promise(x => frame.onload = x);
     return frame;
   }, { frameId, url });
-  return handle.asElement().contentFrame();
+  return handle.asElement().contentFrame() as Promise<Frame>;
 }
 
 export async function detachFrame(page: Page, frameId: string) {
   await page.evaluate(frameId => {
-    document.getElementById(frameId).remove();
+    document.getElementById(frameId)!.remove();
   }, frameId);
 }
 
 export async function verifyViewport(page: Page, width: number, height: number) {
   // `expect` may clash in test runner tests if imported eagerly.
   const { expect } = require('@playwright/test');
-  expect(page.viewportSize().width).toBe(width);
-  expect(page.viewportSize().height).toBe(height);
+  expect(page.viewportSize()!.width).toBe(width);
+  expect(page.viewportSize()!.height).toBe(height);
   expect(await page.evaluate('window.innerWidth')).toBe(width);
   expect(await page.evaluate('window.innerHeight')).toBe(height);
 }
@@ -100,18 +101,18 @@ export async function parseTrace(file: string): Promise<{ events: any[], resourc
     resources.set(entry, await zipFS.read(entry));
   zipFS.close();
 
-  const events = [];
-  for (const line of resources.get('trace.trace').toString().split('\n')) {
+  const events: any[] = [];
+  for (const line of resources.get('trace.trace')!.toString().split('\n')) {
     if (line)
       events.push(JSON.parse(line));
   }
 
-  for (const line of resources.get('trace.network').toString().split('\n')) {
+  for (const line of resources.get('trace.network')!.toString().split('\n')) {
     if (line)
       events.push(JSON.parse(line));
   }
 
-  const stacks = parseClientSideCallMetadata(JSON.parse(resources.get('trace.stacks').toString()));
+  const stacks = parseClientSideCallMetadata(JSON.parse(resources.get('trace.stacks')!.toString()));
   return {
     events,
     resources,
@@ -120,11 +121,11 @@ export async function parseTrace(file: string): Promise<{ events: any[], resourc
   };
 }
 
-function eventsToActions(events: any[]): string[] {
+function eventsToActions(events: ActionTraceEvent[]): string[] {
   // Trace viewer only shows non-internal non-tracing actions.
-  return events.filter(e => e.type === 'action' && !e.metadata.internal && !e.metadata.method.startsWith('tracing'))
-      .sort((a, b) => a.metadata.startTime - b.metadata.startTime)
-      .map(e => e.metadata.apiName);
+  return events.filter(e => e.type === 'action')
+      .sort((a, b) => a.startTime - b.startTime)
+      .map(e => e.apiName);
 }
 
 export async function parseHar(file: string): Promise<Map<string, Buffer>> {
diff --git a/tests/library/tracing.spec.ts b/tests/library/tracing.spec.ts
index 2658f8762b..0593e3ecca 100644
--- a/tests/library/tracing.spec.ts
+++ b/tests/library/tracing.spec.ts
@@ -20,6 +20,7 @@ import path from 'path';
 import { browserTest, contextTest as test, expect } from '../config/browserTest';
 import { parseTrace } from '../config/utils';
 import type { StackFrame } from '@protocol/channels';
+import type { ActionTraceEvent } from '../../packages/trace/src/trace';
 
 test.skip(({ trace }) => trace === 'on');
 
@@ -111,9 +112,9 @@ test('should not include buffers in the trace', async ({ context, page, server,
   await page.screenshot();
   await context.tracing.stop({ path: testInfo.outputPath('trace.zip') });
   const { events } = await parseTrace(testInfo.outputPath('trace.zip'));
-  const screenshotEvent = events.find(e => e.type === 'action' && e.metadata.apiName === 'page.screenshot');
-  expect(screenshotEvent.metadata.snapshots.length).toBe(2);
-  expect(screenshotEvent.metadata.result).toEqual({});
+  const screenshotEvent = events.find(e => e.type === 'action' && e.apiName === 'page.screenshot');
+  expect(screenshotEvent.snapshots.length).toBe(2);
+  expect(screenshotEvent.result).toEqual({});
 });
 
 test('should exclude internal pages', async ({ browserName, context, page, server }, testInfo) => {
@@ -127,7 +128,7 @@ test('should exclude internal pages', async ({ browserName, context, page, serve
   const trace = await parseTrace(testInfo.outputPath('trace.zip'));
   const pageIds = new Set();
   trace.events.forEach(e => {
-    const pageId = e.metadata?.pageId;
+    const pageId = e.pageId;
     if (pageId)
       pageIds.add(pageId);
   });
@@ -139,7 +140,7 @@ test('should include context API requests', async ({ browserName, context, page,
   await page.request.post(server.PREFIX + '/simple.json', { data: { foo: 'bar' } });
   await context.tracing.stop({ path: testInfo.outputPath('trace.zip') });
   const { events } = await parseTrace(testInfo.outputPath('trace.zip'));
-  const postEvent = events.find(e => e.metadata?.apiName === 'apiRequestContext.post');
+  const postEvent = events.find(e => e.apiName === 'apiRequestContext.post');
   expect(postEvent).toBeTruthy();
   const harEntry = events.find(e => e.type === 'resource-snapshot');
   expect(harEntry).toBeTruthy();
@@ -350,9 +351,9 @@ test('should include interrupted actions', async ({ context, page, server }, tes
   await context.close();
 
   const { events } = await parseTrace(testInfo.outputPath('trace.zip'));
-  const clickEvent = events.find(e => e.metadata?.apiName === 'page.click');
+  const clickEvent = events.find(e => e.apiName === 'page.click');
   expect(clickEvent).toBeTruthy();
-  expect(clickEvent.metadata.error.error.message).toBe('Action was interrupted');
+  expect(clickEvent.error.message).toBe('Action was interrupted');
 });
 
 test('should throw when starting with different options', async ({ context }) => {
@@ -395,8 +396,8 @@ test('should work with multiple chunks', async ({ context, page, server }, testI
     'page.click',
     'page.click',
   ]);
-  expect(trace1.events.find(e => e.metadata?.apiName === 'page.click' && !!e.metadata.error)).toBeTruthy();
-  expect(trace1.events.find(e => e.metadata?.apiName === 'page.click' && e.metadata?.error?.error?.message === 'Action was interrupted')).toBeTruthy();
+  expect(trace1.events.find(e => e.apiName === 'page.click' && !!e.error)).toBeTruthy();
+  expect(trace1.events.find(e => e.apiName === 'page.click' && e.error?.message === 'Action was interrupted')).toBeTruthy();
   expect(trace1.events.some(e => e.type === 'frame-snapshot')).toBeTruthy();
   expect(trace1.events.some(e => e.type === 'resource-snapshot' && e.snapshot.request.url.endsWith('style.css'))).toBeTruthy();
 
@@ -472,7 +473,7 @@ test('should hide internal stack frames', async ({ context, page }, testInfo) =>
   await context.tracing.stop({ path: tracePath });
 
   const trace = await parseTrace(tracePath);
-  const actions = trace.events.filter(e => e.type === 'action' && !e.metadata.apiName.startsWith('tracing.'));
+  const actions = trace.events.filter(e => e.type === 'action' && !e.apiName.startsWith('tracing.'));
   expect(actions).toHaveLength(4);
   for (const action of actions)
     expect(relativeStack(action, trace.stacks)).toEqual(['tracing.spec.ts']);
@@ -493,7 +494,7 @@ test('should hide internal stack frames in expect', async ({ context, page }, te
   await context.tracing.stop({ path: tracePath });
 
   const trace = await parseTrace(tracePath);
-  const actions = trace.events.filter(e => e.type === 'action' && !e.metadata.apiName.startsWith('tracing.'));
+  const actions = trace.events.filter(e => e.type === 'action' && !e.apiName.startsWith('tracing.'));
   expect(actions).toHaveLength(5);
   for (const action of actions)
     expect(relativeStack(action, trace.stacks)).toEqual(['tracing.spec.ts']);
@@ -606,7 +607,7 @@ function expectBlue(pixels: Buffer, offset: number) {
   expect(a).toBe(255);
 }
 
-function relativeStack(action: any, stacks: Map<string, StackFrame[]>): string[] {
-  const stack = stacks.get(action.metadata.id) || [];
+function relativeStack(action: ActionTraceEvent, stacks: Map<string, StackFrame[]>): string[] {
+  const stack = stacks.get(action.callId) || [];
   return stack.map(f => f.file.replace(__dirname + path.sep, ''));
 }