Implement candidate deduplication logic before creating ATS records

Steps

1. Before creating a new candidate, query the ATS candidates search endpoint (e.g., Greenhouse Harvest GET /v1/candidates?email={email}) to check for existing records with the same email address
2. If no exact email match is found, perform a fuzzy name-plus-phone search using available ATS search parameters to catch cases where the candidate used a different email
3. Define a deduplication policy: exact email match always merges; name-only match prompts human review; no match creates a new record
4. If the ATS supports a merge API (e.g., Greenhouse Harvest PUT /v1/candidates/{id}/merge), call it to consolidate duplicate records, designating one as the primary
5. Log all merge decisions with the source data, matched fields, and outcome for audit and rollback purposes