[Feature] Add retry limit and backoff to InteractionTracker event submission

[numbers-official]

Summary

The InteractionTracker.createEvent() method in src/modal/interaction-tracker.ts retries indefinitely when the authentication token has not yet been fetched, creating a potential resource leak and degraded user experience on slow or failing networks.

Affected File

src/modal/interaction-tracker.ts — Lines 44–56

Details

When this.token is null (token fetch still in progress), the createEvent method recursively schedules itself via setTimeout every 1 second with no retry limit:

private createEvent(name, datetime, nid, subid): void {
  const token = this.token;
  if (token === null) {
    setTimeout(() => {
      this.createEvent(name, datetime, nid, subid);
    }, 1000);
    return;
  }
  // ...
}

If the token fetch takes a long time or the CDN is unreachable, every tracked interaction queues an unbounded retry chain. On a page with multiple capture-eye elements, this compounds:

• N elements x M interactions x unlimited retries = significant accumulated setTimeout callbacks
• Each retry closure retains references to its arguments, preventing garbage collection
• On mobile devices with limited resources, this degrades performance

Proposed Approach

1. Add a max retry count (e.g., 5 retries) with exponential backoff (1s, 2s, 4s, 8s, 16s):

private createEvent(name, datetime, nid, subid, retryCount = 0): void {
  const MAX_RETRIES = 5;
  const token = this.token;
  if (token === null) {
    if (retryCount >= MAX_RETRIES) {
      console.warn('Event tracking abandoned after max retries:', name);
      return;
    }
    const delay = Math.min(1000 * Math.pow(2, retryCount), 16000);
    setTimeout(() => {
      this.createEvent(name, datetime, nid, subid, retryCount + 1);
    }, delay);
    return;
  }
  // ...
}

2. Optional: Queue events instead of retrying each individually. Buffer events in an array and flush the queue once the token becomes available, avoiding per-event retry chains entirely.

Expected Impact

• Prevents unbounded retry loops on slow/unreachable networks
• Reduces memory pressure from accumulated closures on pages with many capture-eye instances
• Graceful degradation: analytics are best-effort, not blocking
• No breaking changes to public API
• Estimated effort: 1-2 hours