For the final shortlist, I’d create a one-page summary per apartment: confirmed location, current status, area explanation, price trail, contact history and unresolved points.
The promotion rule could be simple: suitable broad location, plausible price, acceptable basic details and either confirmed availability or a meaningful response.
That may eliminate potentially suitable apartments too early. A separate “location pending” queue keeps them visible without granting full-shortlist status.
For privacy and simplicity, keep only information needed for the property search. The useful record is about listings and responses, not unnecessary personal details.
What would make Idealista the primary shortlist rather than just discovery? For me, it would require clearer freshness, stronger duplicate handling and consistent area fields—the exact gaps Jin identified.
Price history and sold-record links would improve context, but they are secondary to knowing that the listed apartment exists, fits the area and is still available.