Why: plan U6 vector slice (KTD11 correctness step) - same-dimension vectors from different models must never mix, and PG tiers should run filtered exact top-k in the database instead of scanning every row in-process.
Evidence: full suite green on SQLite and real PostgreSQL 18.6 with pgvector (35 packages each tier) - pgvector_test covers model-identity and dimension isolation, update/delete atomicity (BLOB and vec_pg swap together), shared top-5 with score monotonicity, Recall@10 = exact-scan parity, deny-all predicate leakage; storage-migrate tests green after excluding the derived vec_pg column.
Impact: v25 migration adds model/content_hash columns and (PG, best-effort DO block) the pgvector extension plus vec_pg column - absence degrades to in-process scan; UpsertKnowledgeVectorExt dual-writes BLOB (cross-tier authority) and vec_pg; SearchKnowledgeVectorsModel/SharedModel filter by model identity and use SQL exact top-k (ORDER BY vec_pg <=> q) with automatic degradation; embedders expose Model() and the rag pipeline threads it through indexing and both retrieve paths; storage-migrate excludes vec_pg as a derived column.
Refs: proposals/2026-10-11-collaboration-storage-and-distribution.md U6 slice 3, KTD11; R9.
Why: Downstream products must extend the base through a public package and host API instead of editing internal code.
Evidence: go test ./... passed, including plugin v2 assets, sidecar startup, migration v13, pending confirms, HITL timeout, hash embedder, command pairs, and the extension surface snapshot.
Impact: apiVersion 2.0-experimental rejects empty network allowlists for declarative HTTP. Hash embeddings stay opt-in via models.embedding.provider=hash. Plugin secrets resolve per owner at execution time.
Refs: docs/proposals/2026-10-01-plugin-contract-v2.md
Co-authored-by: Cursor <cursoragent@cursor.com>
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