Commercial Extension Points

The free interoperability rails compute the consequences of declarations; commercial products supply, and verification tools audit, the declarations themselves. This is the crawlable catalogue of where a paid surface plugs in — and the declaration contract it must publish — with no product, price, or pitch.

The conversion tools in this knowledge base are free, unauthenticated, and unbranded, and they stay that way. They compute the consequences of a declaration — the cells a polygon becomes, the overreach a cover introduces, the weights a crosswalk implies. What they never do is supply the declaration itself: they do not own a population surface, a similarity definition, or a measured positional error. Those are commercial extension points, and this page is the public catalogue of where they attach.

It exists so a refusal has somewhere to point. When a request is out of scope for the free tools, the honest answer is not a silent decline — it is a citation to this page and the declaration contract the plug-in must publish. The describe_extension_points MCP tool returns exactly this catalogue and this URL.

The design rule

Consequences are free; declarations are supplied and audited

The free rails compute the consequences of declarations. Commercial tools supply declarations (a population surface, a place-embedding space); verification tools audit them (a signed positional error, a model fingerprint). Every socket is filled by one wire shape — a registry row: supplier, version, declared grain, validity window. The rails record the row and compute its consequence; they never invent what the row asserts.

The sockets

population_surface (supply): The temporal denominator: hour-of-week population per cell. Must declare data source, spatial-mapping method, temporal methodology, vintage, unit. See the worked example → Population surface declaration.
place_representation (supply): Place-resemblance backed by a registered embedding space. Must declare the similarity definition, data sources, granularity, and the named embedding space — the rails never define 'similar'.
model_verification (verify): A non-cooperative check of a vector sample against a claimed model registry entry. Must declare model name, version, supplier, declared geometric fingerprint, valid_from / valid_to. Geometry-only; no model access.
error_assignment (audit): A signal's declared positional error — the input the free point→cell tools consume. Must declare per-vendor / per-venue measured error, signer identity, method, valid_from / valid_to. For IP geolocation, this is the containment calibration: measured coverage of the declared-confidence disk against a ground-truth sample, per country or region.
location_crosswalk (supply): A probabilistic location source expressed as the weighted cell crosswalk it actually is: network block → {cell, p} rows at a declared resolution, confidence-convention normalized, with the database release as the vintage. Must declare supplier, db vintage with validity window, confidence convention, kernel or empirical basis, and a containment calibration attestation. The free rails compute single-lookup consequences (see IP lookup to H3); the supplied crosswalk is the precomputed, attested bulk form.
experiment_design (supply): Market matching, power, and lift readout atop the free conversions. Must declare the design (matched-market vs stratified-random), power assumptions, readout methodology, version.

The registry row

Every socket, whatever it supplies, publishes the same shape — the same shape the weighted crosswalk records for a declared mass surface and a boundary crosswalk records as regionProvenance:

supplier: Who stands behind the declaration.
version: The edition of the supplied surface / model / method.
grain: The declared spatial and temporal grain the row is valid at.
valid_from / valid_to: The applicability window — a declaration is only as current as its vintage.

Naming the sockets is not selling them. This page documents where a conformant supplier declaration attaches and what it must contain; it carries no product, no price, and no partner pitch. A supplier is conformant when it publishes this row and the rails can compute its consequence — nothing more is asserted here.