NIP-XX: NIP-99 Marketplace Listing Extension

[pats2sats]

Summary

Adds a generic marketplace extension for NIP-99 classified listings. The proposal defines shared listing tags and profile conventions that can be reused across marketplace verticals such as accommodation, vehicles, goods, rentals, and services.

What this defines

• Marketplace profile tags using t values.
• Generic listing tags for auto-acceptance, negotiability, rent-or-buy mode, duration limits, quantity, security deposit, minimum payment, maximum dispute period, and cancellation policy.
• Promoted tag conventions for relay-filterable fields.
• Guidance for profile-specific location encodings and client behavior.

Scope

This provides the generic listing layer. Profile-specific tags, such as accommodation features or other vertical-specific promoted tags, belong in separate profile specifications.

[ericfj2140]

Since this extension introduces rentOrBuy, minDuration, bookable quantity, and cancellation rules relative to an order start, could it explicitly define the boundary between generic rental terms and dated availability?

I do not think the generic listing layer needs to depend directly on NIP-52 or define an accommodation calendar. It would be useful, however, to state that these tags describe duration, capacity, and commercial policy only; they do not define which dates are available or how overlapping reservations consume inventory. Marketplace profiles or the order/availability layer would define those semantics, potentially reusing NIP-52 for calendar intervals.

That scope statement would prevent clients from interpreting quantity as either undated global stock or per-date capacity without knowing which model applies, and it would give accommodation and other rental profiles a clean place to standardize availability separately.