Local RAG

Semantic search over local files using all-MiniLM-L6-v2 embeddings and ms-marco-MiniLM-L-6-v2 cross-encoder reranking with ChromaDB and parent-child chunking. Optimized for low-RAM ARM devices (Raspberry Pi). Use when the user asks questions about their documents, wants to find information in their files without specifying exact paths, or needs to search across PDFs, DOCX, TXT, MD, TEX files. Triggers on "cerca nei miei file", "find in my files", "search documents", "trova nel computer", "what does my thesis say about", "search notes". NOT for exact file path requests, web search, or sending files.

Semantic search over indexed local files with parent-child chunking for precise retrieval with full context.

Architecture

Component	Model	Size
Embeddings	sentence-transformers/all-MiniLM-L6-v2	~80MB
Reranker	cross-encoder/ms-marco-MiniLM-L-6-v2	~80MB
Vector DB	ChromaDB (persistent, cosine similarity, HNSW)	varies
Chunking	Parent-child	—

Memory strategy: Embedding model loaded first → freed with gc.collect() → reranker loaded → freed after scoring. This keeps peak RAM ~400MB on ARM.

Chunking Strategy

• Child chunks: 128 words, 24 overlap → embedded for semantic search
• Parent chunks: 768 words → stored as full context, returned to user
• When a child matches → its parent is returned, giving surrounding context

Running

All scripts must use the venv Python:

bash

VENV=~/.local/share/local-rag/venv/bin/python

Indexing

bash

# Incremental index (default — skips unchanged files via SHA-256 hash)
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/index.py

# Re-index from scratch
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/index.py --reindex

# Custom paths
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/index.py --paths ~/Documenti ~/Progetti

# Batch indexing (per-subfolder with git checkpoints, for low-RAM systems)
bash ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/index-batch.sh

Querying

bash

# Basic query
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/query.py "what are the termination clauses?"

# More results
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/query.py "Falcon LLM" --top-k 30 --top-n 5

# JSON output for programmatic use
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/query.py "transformer architecture" --json

# With timeout
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/query.py "deep learning" --timeout 60

Options:

• --top-k N — Child candidates from vector search (default: 20)
• --top-n N — Final parent results after reranking (default: 3)
• --json — JSON output
• --timeout N — Max seconds per query (default: 120)

Monitoring

bash

$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/monitor.py              # Status
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/monitor.py --watch      # Auto-refresh
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/monitor.py --log        # Logs
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/monitor.py --errors     # Errors only
$VENV ~/.openclaw/workspace/skills/lookupmark-local-rag/scripts/monitor.py --git        # Git checkpoints

Supported Formats

Documents only (no code files):

• Text: .txt, .md, .csv, .json, .yaml, .yml, .toml, .tex, .bib
• Documents: .pdf (pdfminer.six), .docx (python-docx), .pptx

Excluded: .py, .js, .sh, .ipynb, .html, .css and all code files.

Limits (for 4GB ARM)

• PDF max size: 5MB (larger PDFs cause OOM with pdfminer)
• Max file size: 30MB
• Embedding batch size: 1 (conservative)
• Excluded dirs: .git, .venv, node_modules, __pycache__, labs, exercises, src, scripts, ablation, test*, fixtures

Storage

Path	Purpose
~/.local/share/local-rag/chromadb/	ChromaDB data (git repo for rollback)
~/.local/share/local-rag/venv/	Python venv with dependencies
~/.local/share/local-rag/index.lock	Prevents concurrent indexing
~/.local/share/local-rag/index-batch.log	Batch indexing log
~/.local/share/local-rag/queries.log	Query history log

Security

• ALLOWED_ROOTS: Only ~/Documenti/github/thesis, ~/Documenti/github/polito, ~/Documenti, ~/Scaricati
• BLOCKED_PATTERNS: .ssh, .gnupg, .env, credentials, tokens, .config/openclaw
• Credentials directory is blacklisted — never indexed

Workflow

1. Run index.py — builds/rebuilds the index (incremental via SHA-256 hash check)
2. Run periodically to pick up new/changed files (daily cron recommended)
3. Use query.py to search with natural language
4. Results include: file path, relevance score, matched snippet, full parent context
5. Check monitor.py for stats and queries.log for query history