Use deterministic duplicate matching

Context

Staff need scores they can reproduce and reasons they can inspect.

Decision

Equality keys select comparisons and a versioned scoring table determines their strength; detection, review and merging make no model calls.

Alternatives Considered

Use a model for matching. The recorded choice requires repeatable matching and explanations derived from evidence.

Use fuzzy database searches. The documented database setup and row policies do not support the proposed extension.

Consequences

All callers declare an empty inference list. Reversing a comparison preserves its calculated result. Calibration still needs synthetic examples and accumulated review decisions.