feat: capture page views and surface as page_events in selectPlacements

[alexs-mparticle]

Summary

Captures page-view events as they are logged, persists them in the kit's own localStorage (separate from mParticle persistence and cookie sync), and surfaces them as a stringified page_events array on the next selectPlacements call as targeting context.

What's included

• Capture (process → capturePageView): page views (EventDataType === 3) are appended to a kit-owned mpPageViews list in localStorage. Each record stores pageUrl (from window.location.href, query string stripped), sourceMessageId, timestamp, and activeTimeOnSite. Capture runs independently of setLocalSessionAttribute availability, since the kit controls its own storage.
• Fixed count cap: the list is capped at 25 records, evicting the oldest first. A simple, predictable limit — no storage-backend sniffing.
• timeOnPage (buildPageEvents): each entry carries a derived timeOnPage — the active time a page was viewed before the next page view was logged (diff of consecutive activeTimeOnSite). Emitted only when it's a genuine non-negative number; omitted for the still-open last entry, negative diffs, and non-numeric values. Derived at read time — nothing extra persisted.
• Feeding selectPlacements: the stored page views are read back, flattened via buildPageEvents, and sent as a stringified page_events array alongside the other placement attributes.

Storage & error handling

The kit owns its localStorage directly rather than writing through mParticle's local-session-attribute store, so page-view capture no longer touches mParticle persistence or cookie sync.

• Read (readPageViewsStorage): guarded — returns an empty array when nothing is stored, the value can't be parsed, or localStorage is unavailable (Safari private mode, storage disabled).
• Write (writePageViewsStorage): a failure (quota exceeded, storage disabled) is caught in capturePageView and surfaced as a PAGE_VIEW_CAPTURE_FAILED WARNING, bounded by the reporting service's per-severity rate limiter, without ever throwing out of the forwarder.

Testing

Navigate through pages on an MPA, then inspect the kit-owned store in the dev console:

JSON.parse(window.localStorage.getItem('mpPageViews'))

Expected result:

[
    {
        "pageUrl": "https://www.domain.com/",
        "sourceMessageId": "80588459-ea2c-491a-9f41-2acc15b8cfb8",
        "timestamp": 1785526522349,
        "activeTimeOnSite": 328892
    },
    {
        "pageUrl": "https://www.domain.com/page_1",
        "sourceMessageId": "88a1ef32-83fd-41a8-03d8-04c4c67c879d",
        "timestamp": 1785526728989,
        "activeTimeOnSite": 364827
    }
]

Verify the expected payload when making a selectPlacements call:

{
  "active_time_on_site_ms": "427361",
  "page_events": "[ /* stringified array of events, each with a derived timeOnPage */ ]",
  // other placement attributes
}

[jamesnrokt]

Requesting changes as we definitely need the cleansing of the URL in before go live

[jamesnrokt]

Final remaining comment I know you're already addressing is clearing out storage on session

[rmi22186]

I noticed that Event.EventAttributes were removed between commits at some point. If that is the intent, then this LGTM

[jamesnrokt]

Thanks for your efforts on this - apologies for the many questions

[mparticle-automation]

🎉 This PR is included in version 1.30.0 🎉

The release is available on:

• v1.30.0
• GitHub release

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