Fix crashes due to large content time jumps in updateDurationStats in media tracking

Add a MAX_CONTENT_TIME_STEP (3600s) gap guard to the playedSeconds fill loop
in updateDurationStats. When contentTime jumps beyond this threshold (e.g.
live stream epoch offsets or large VOD seeks), the per-second loop is skipped
and only the current second is recorded, preventing RangeError crashes from
unbounded Set growth or billions of iterations.

Author: matus-tomlein

common/changes/@snowplow/browser-plugin-media/release-4.6.9_2026-03-16-08-58.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@snowplow/browser-plugin-media",
+      "comment": "Fix crashes due to large content time jumps in updateDurationStats in media tracking",
+      "type": "none"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-media"
+}

plugins/browser-plugin-media/src/sessionStats.ts

@@ -17,6 +17,12 @@ type Log = {
   linearAd: boolean;
 };
 
+/** Maximum content-time gap (seconds) for which intermediate seconds are filled into playedSeconds.
+ *  Beyond this threshold only the current second is recorded, preventing unbounded iteration
+ *  for live streams or large VOD seeks where currentTime can be a huge offset.
+ */
+const MAX_CONTENT_TIME_STEP = 3600;
+
 const adStartTypes = [MediaEventType.AdStart, MediaEventType.AdResume];
 const adProgressTypes = [
   MediaEventType.AdClick,
@@ -134,9 +140,13 @@ export class MediaSessionTrackingStats {
         }
 
         if (!log.paused) {
-          for (let i = Math.floor(this.lastLog.contentTime); i < log.contentTime; i++) {
-            this.playedSeconds.add(i);
+          const gap = log.contentTime - this.lastLog.contentTime;
+          if (gap <= MAX_CONTENT_TIME_STEP) {
+            for (let i = Math.floor(this.lastLog.contentTime); i < log.contentTime; i++) {
+              this.playedSeconds.add(i);
+            }
           }
+          // gap > MAX_CONTENT_TIME_STEP: skip loop, only current second is recorded below
         }
       }
     }

plugins/browser-plugin-media/test/sessionStats.test.ts

@@ -188,6 +188,46 @@ describe('MediaSessionTrackingStats', () => {
     expect(entity.timePlayedMuted).toBe(30);
   });
 
+  it('does not crash when content time jump exceeds MAX_CONTENT_TIME_STEP', () => {
+    let session = new MediaSessionTrackingStats();
+
+    session.update(MediaEventType.Play, { ...mediaPlayerDefaults, currentTime: 0 });
+
+    jest.advanceTimersByTime(1000);
+    session.update(MediaEventType.SeekEnd, { ...mediaPlayerDefaults, currentTime: 7200 });
+
+    expect(() => session.toSessionContextEntity()).not.toThrow();
+    let entity = session.toSessionContextEntity();
+    // Loop is skipped; only the start second (0) and the landed second (7200) are recorded
+    expect(entity.contentWatched).toBeLessThanOrEqual(3);
+  });
+
+  it('does not crash when livestream currentTime is a large Unix-epoch offset', () => {
+    let session = new MediaSessionTrackingStats();
+
+    const epochBase = 1_700_000_000;
+
+    session.update(MediaEventType.Play, { ...mediaPlayerDefaults, livestream: true, currentTime: epochBase });
+
+    jest.advanceTimersByTime(1000);
+    // Jump larger than MAX_CONTENT_TIME_STEP — simulates stream discontinuity
+    session.update(MediaEventType.Ping, { ...mediaPlayerDefaults, livestream: true, currentTime: epochBase + 7200 });
+
+    expect(() => session.toSessionContextEntity()).not.toThrow();
+  });
+
+  it('still fills intermediate seconds for gaps within MAX_CONTENT_TIME_STEP', () => {
+    let session = new MediaSessionTrackingStats();
+
+    session.update(MediaEventType.Play, { ...mediaPlayerDefaults, currentTime: 0 });
+
+    jest.advanceTimersByTime(30 * 1000);
+    session.update(MediaEventType.End, { ...mediaPlayerDefaults, currentTime: 30 });
+
+    let entity = session.toSessionContextEntity();
+    expect(entity.contentWatched).toBe(31);
+  });
+
   it('calculates buffering time', () => {
     let session = new MediaSessionTrackingStats();