ADR 0003: Provider and fetcher model

Context

Website-shaped facades couple public APIs to unstable source routes.

Decision

Providers advertise capabilities; typed fetchers separate query normalization, extraction, and pure transformation.

Alternatives

One large provider class and dynamically shaped dictionary calls were considered.

Consequences

Source changes remain within adapters and capability discovery is explicit.

Rejected shortcuts

Fallback-by-exception and implicit endpoint selection are rejected.

Operational implications

New capabilities require catalog evidence, models, transforms, fixtures, and tests.