---
category: reference
tags: [tasks, semantic-search, faiss, multi-tenant]
last_updated: 2026-03-20
confidence: high
---

# Semantic Search Multi-Tenant — IMPLEMENTED

## Solution (2026-03-20)

All multi-tenant issues resolved. FAISS backend with `BackendRegistry` provides per-wiki isolation.

### Implementation
- **BackendRegistry** manages per-wiki FAISS backends with lazy initialization
- **Per-wiki FAISS indexes** at `/srv/data/faiss/{slug}/` — natural isolation, no slug-prefix hacking
- **Lifecycle hooks** (`page_saved`/`page_deleted`/`page_renamed`) via `HookListener` replace the single-tenant sync thread
- **`reindex_all` is per-wiki scoped** — reindexing one wiki does not affect others
- **Auto-index on first access** — existing pages are back-filled when a wiki is first accessed
- **ONNX MiniLM-L6-v2 embeddings** (ChromaDB bundled) — no model download issues
- ChromaDB deprecated and disabled

### Original problems (all resolved)

1. **One shared ChromaDB collection** — Replaced by per-wiki FAISS directories.
2. **One sync thread** tied to default wiki — Replaced by per-request lifecycle hooks.
3. **`reindex_all` wipes everything** — Now per-wiki scoped.
4. **No auto-index for new wikis** — Auto-reindex on first wiki access.
5. **Embedding model download** — ONNX model bundled, no download needed.

## Related
- [[Tasks/Semantic_Search_Architecture]] — overall architecture
- [[Dev/Proxmox_CPU_Type]] — numpy X86_V2 issue (workaround in place)
- [[Design/Async_Embedding_Pipeline]] — original FAISS + MiniLM design (AWS, archived)