Adds semantic search with vector recall + reranking + provenance walking:
Changes to crates/mem-cli/src/main.rs:
- Add Query command variant with flags: --project, --levels, --k, --format, --explain
- Add cmd_query handler: embed → recall → rerank → format output
- Support both text and JSON output formats
Changes to crates/mem-cli/src/query_worker.rs:
- Implement reranking in QueryWorker::query()
- Recall 10×k candidates (capped at 50), rerank to top-k
- Fall back to vector similarity if reranker fails
- Handle reranker index mapping correctly (bare array format)
Changes to crates/mem-store/src/pgvector.rs:
- Add pool() method for test access to connection pool
New file: tests/it_query.rs
- 8 integration tests (6 ignored, require live DB + gateway):
a1_known_answer: query returns correct L1 node first
a2_provenance_resolves: every hit's parents exist in DB
a3_default_excludes_l0: default output has no L0
a4_levels_flag: --levels L0 returns evidence
a5_rerank_reorders: pre/post rerank order differs
a6_project_isolation: no cross-project hits
a7_no_project_errors: bad project returns empty
a8_l2_two_hop_provenance: L2→L1→L0 chain resolves
- Seeded test DB fixture with L0/L1/L2 nodes
Pipeline:
embed question → HNSW recall (10×k, cap 50) → rerank → top-k → render
Blocked on: M3.2 (✅ done), M2.1 (✅ done), M2.4 (✅ done)
