ADR-006: Ingest–Query Routing Contract

Status: Accepted

Decision

• Ingest writes documents.extra.collections_used and knowledge_bases.collections_used on success only (G30).
• Query scope-aware union forces specialized collection plans when scope KBs/documents/tags catalog includes them (G21/G23/G29).
• Tags resolve via resolve_tags_to_document_ids(plugin_namespace, tags) then document catalog union.