-- Proposed optional phase. NOT applied by the ordinary migration runner.
-- Requires an approved pgvector installation in the SAME InvestMoz database,
-- a benchmarked embedding model and a reviewed backup/rollback plan.
-- BGE-M3 candidate dimension: 1024. Changing the model requires a new embedding
-- version and reindexing, not mixing incomparable vectors.
CREATE TABLE ai_embeddings (
    chunk_id uuid NOT NULL REFERENCES ai_chunks(id) ON DELETE RESTRICT,
    model_id text NOT NULL,
    model_revision text NOT NULL,
    content_checksum char(64) NOT NULL,
    embedding vector(1024) NOT NULL,
    created_at timestamptz NOT NULL DEFAULT now(),
    PRIMARY KEY (chunk_id, model_id, model_revision)
);
-- Start with exact filtered search, then benchmark HNSW with real ACL filters.
-- Eligible sources must be filtered using the same rules as EvidenceRepository;
-- matching model/revision/checksum is mandatory BEFORE fusion and reranking.
-- Do not run CREATE EXTENSION against an unverified PostgreSQL installation.