Canonicalize provider-equivalent identifiers before deduplication

When an external provider accepts several literal identifiers for the same business object, creation and duplicate checks must not key only on the submitted string. Preserve the original identifier for audit, but also derive and store a canonical provider identity, then use organization plus canonical identity plus assignment identity for duplicate detection. Otherwise a compound identifier and its base identifier can create separate local records even though both provider lookups resolve to the same object. This does not authorize merging records when suffixes carry independent business meaning; the normalization contract must come from the provider adapter and be covered by collision tests.

Applies when: intake accepts aliases, compound IDs, or dispatch-qualified identifiers that normalize to one provider object. Keywords: external identifier canonicalization deduplication aliases compound load id provider identity