✨ [RUM-6563] Attribute ressource URL to LCP

packages/rum-core/src/browser/performanceObservable.ts

@@ -91,6 +91,7 @@ export interface RumLargestContentfulPaintTiming {
   startTime: RelativeTime
   size: number
   element?: Element
+  url?: string
   toJSON(): Omit<RumLargestContentfulPaintTiming, 'toJSON'>
 }
 

packages/rum-core/src/domain/view/trackViews.spec.ts

@@ -531,7 +531,7 @@ describe('view metrics', () => {
           jasmine.objectContaining({
             firstContentfulPaint: 123 as Duration,
             navigationTimings: jasmine.any(Object),
-            largestContentfulPaint: { value: 789 as Duration, targetSelector: undefined },
+            largestContentfulPaint: { value: 789 as Duration, targetSelector: undefined, resourceUrl: undefined },
           })
         )
       })

packages/rum-core/src/domain/view/viewCollection.spec.ts

@@ -202,6 +202,7 @@ describe('viewCollection', () => {
           lcp: {
             timestamp: (10 * 1e6) as ServerDuration,
             target_selector: undefined,
+            resource_url: undefined,
           },
         },
         resource: {

packages/rum-core/src/domain/view/viewCollection.ts

@@ -183,6 +183,7 @@ function computeViewPerformanceData(
     lcp: largestContentfulPaint && {
       timestamp: toServerDuration(largestContentfulPaint.value),
       target_selector: largestContentfulPaint.targetSelector,
+      resource_url: largestContentfulPaint.resourceUrl,
     },
   }
 }

packages/rum-core/src/domain/view/viewMetrics/trackLargestContentfulPaint.spec.ts

@@ -45,7 +45,11 @@ describe('trackLargestContentfulPaint', () => {
     startLCPTracking()
     notifyPerformanceEntries([createPerformanceEntry(RumPerformanceEntryType.LARGEST_CONTENTFUL_PAINT)])
 
-    expect(lcpCallback).toHaveBeenCalledOnceWith({ value: 789 as RelativeTime, targetSelector: undefined })
+    expect(lcpCallback).toHaveBeenCalledOnceWith({
+      value: 789 as RelativeTime,
+      targetSelector: undefined,
+      resourceUrl: undefined,
+    })
   })
 
   it('should provide the largest contentful paint target selector', () => {
@@ -56,7 +60,26 @@ describe('trackLargestContentfulPaint', () => {
       }),
     ])
 
-    expect(lcpCallback).toHaveBeenCalledOnceWith({ value: 789 as RelativeTime, targetSelector: '#lcp-target-element' })
+    expect(lcpCallback).toHaveBeenCalledOnceWith({
+      value: 789 as RelativeTime,
+      targetSelector: '#lcp-target-element',
+      resourceUrl: undefined,
+    })
+  })
+
+  it('should provide the largest contentful paint target url', () => {
+    startLCPTracking()
+    notifyPerformanceEntries([
+      createPerformanceEntry(RumPerformanceEntryType.LARGEST_CONTENTFUL_PAINT, {
+        url: 'https://example.com/lcp-resource',
+      }),
+    ])
+
+    expect(lcpCallback).toHaveBeenCalledOnceWith({
+      value: 789 as RelativeTime,
+      targetSelector: undefined,
+      resourceUrl: 'https://example.com/lcp-resource',
+    })
   })
 
   it('should be discarded if it is reported after a user interaction', () => {

packages/rum-core/src/domain/view/viewMetrics/trackLargestContentfulPaint.ts

@@ -13,6 +13,7 @@ export const LCP_MAXIMUM_DELAY = 10 * ONE_MINUTE
 export interface LargestContentfulPaint {
   value: RelativeTime
   targetSelector?: string
+  resourceUrl?: string
 }
 
 /**
@@ -57,7 +58,6 @@ export function trackLargestContentfulPaint(
         // https://bugs.chromium.org/p/chromium/issues/detail?id=1516655
         entry.size > biggestLcpSize
     )
-
     if (lcpEntry) {
       let lcpTargetSelector
       if (lcpEntry.element) {
@@ -67,6 +67,7 @@ export function trackLargestContentfulPaint(
       callback({
         value: lcpEntry.startTime,
         targetSelector: lcpTargetSelector,
+        resourceUrl: lcpEntry.url,
       })
       biggestLcpSize = lcpEntry.size
     }

packages/rum-core/src/rawRumEvent.types.ts

@@ -175,6 +175,7 @@ export interface ViewPerformanceData {
   lcp?: {
     timestamp: ServerDuration
     target_selector?: string
+    resource_url?: string
   }
 }
 

packages/rum-core/src/rumEvent.types.ts

@@ -1712,6 +1712,10 @@ export interface ViewPerformanceData {
      * CSS selector path of the largest contentful paint element
      */
     readonly target_selector?: string
+    /**
+     * URL of the largest contentful paint element
+     */
+    readonly resource_url?: string
     [k: string]: unknown
   }
   [k: string]: unknown