Sylin.Koan.Data.SearchEngine

Koan.Data.SearchEngine

Shared support for the search-engine vector connectors — Koan.Data.Connector.ElasticSearch and Koan.Data.Connector.OpenSearch. Both engines are built on Apache Lucene and speak the same query DSL, so the metadata-filter translation lives here once instead of being duplicated per adapter. The package is named for the engine category (the same convention as Koan.Data.Relational), so the dependency reads clearly without Lucene-internals knowledge.

• SearchEngineFilterTranslator — the single source of truth for translating the unified Filter AST into the Elasticsearch/OpenSearch query DSL, plus the one VectorFilterCapabilities constant both adapters expose.

Capabilities

• Translate the unified Filter AST → the search-engine query DSL (term/terms/range/wildcard/ bool/exists).
• One operator-aware VectorFilterCapabilities value shared by both adapters.
• Null-inclusive negation (Ne/Nin/HasNone) via Lucene bool/must_not.

Usage

Each connector calls the shared translator, passing its own engine label so a not-supported error names the right adapter:

var query = SearchEngineFilterTranslator.TranslateWhereClause(
    options.Filter, metadataField, engine: "Elasticsearch");

Notes:

• The engine label only personalizes not-supported exception messages; the translation is identical.
• The repositories stay separate (their REST/transport wiring differs); only the translation and the capability constant are shared.

References

• Vector pathway + filter model: ~/decisions/DATA-0097-vector-pathway-parity.md
• Embedding↔vector seam (§10.4, the ES/OS shared base): ~/decisions/AI-0036-embedding-vector-seam.md