recall

A long-running agent piles up memory — decisions, closed experiments, incident notes. Two failure modes follow: it re-litigates settled decisions, and it hallucinates over gaps where the memory simply has no answer.

RE-call is a RAG engine for that memory, built to be honest about what it doesn't know: it retrieves before the agent acts, and flags when the memory probably has no answer instead of returning confident noise.

✨ What it does

• 🕳️ Gap-aware — when the best match is weak, it returns a gap_warning ("probable corpus gap — treat as noise") instead of hallucinating an answer.

• ⏱️ Freshness-aware — every result reports how stale the index is, so a rotting memory warns instead of silently serving old facts.

• 🔁 Anti-re-litigation — meant to be queried before re-proposing an idea, so closed decisions and falsified hypotheses resurface first.

• 🧱 Production-shaped — PostgreSQL + pgvector, hybrid dense + full-text retrieval fused with RRF, cross-encoder reranking, and an MCP server. Integration-tested on a real database.

Related MCP server: yantrikdb-mcp

🧭 How it works

flowchart LR
    Q([query]) --> E[embed]
    E --> D[dense · pgvector cosine]
    Q --> S[sparse · Postgres full-text]
    D --> F[Reciprocal Rank Fusion]
    S --> F
    F --> R[cross-encoder rerank]
    R --> G{honesty guards}
    G --> O([hits + gap_warning + freshness])

Dense semantic search and sparse keyword search each retrieve candidates; Reciprocal Rank Fusion merges them, a cross-encoder reranks, and the honesty guards annotate the result before it ever reaches the agent.

⚡ See it work

$ python -m recall.cli demo
indexed 3 chunks from 3 files

[ok]  query='what did we decide about caching?'
  0.736  corpus/decisions.md   '# Decisions  ## 2026-05-02 — Caching layer We decided to add a read-th…'

[ok]  query='do we inject retrieved context into the prompt?'
  0.809  corpus/hypotheses.md  '# Hypotheses  ## H-014 — Prompt-injected context improves answers (CLO…'

[GAP] query='how do we handle penguins on mars?'
  0.468  corpus/decisions.md   '# Decisions  ## 2026-05-02 — Caching layer We decided to add a read-th…'

The two answerable queries return strong hits (0.74, 0.81). The deliberately-unanswerable one's best match is only 0.468 — below the 0.50 gap threshold — so it's flagged [GAP] instead of handing back that irrelevant chunk as if it were an answer. That single flag is the whole thesis.

📊 Results that matter

A reproducible ablation harness scores every embedder × fusion config on a labelled query set — precision@k, recall@k, MRR, nDCG, and a guard-specific false-confident rate.

Three honest findings — including what didn't work:

• 🎯 The gap threshold doesn't transfer across embedders. The default 0.50 gives a 0.80 false-confident rate on FastEmbed (its cosines cluster high); per-embedder calibration to ~0.70 makes the guard perfect. → Calibrate against a small labelled set; don't hard-code.

• 🔁 Reranking rescues a weak embedder. Hybrid + cross-encoder lifts MRR 0.68 → 1.00 on the offline embedder — but a strong embedder already saturates this corpus, so the gain is real yet situational.

• 🧪 Fine-tuning the embedder pays off only for a vocabulary gap. A controlled study: on a rich corpus the base already saturates (Δ +0.00); on an opaque-jargon corpus it can't decode, fine-tuning lifts held-out MRR 0.31 → 0.55 (+79%) and generalizes to unseen paraphrases. → Measure the base–corpus gap before fine-tuning. Read the study →

Full methodology + per-embedder tables → results/FINDINGS.md.

✅ 46 integration tests run against a real pgvector container (no mock DB), verified in CI, with a dependency audit.

🏭 Where this comes from

RE-call isn't a toy — it's extracted from the memory system I run for a production trading-research agent whose own memory outgrew its context window: ≈660 typed markdown memos (~5 MB), re-indexed daily. Every guard here is a scar from a real failure — re-litigating an already-falsified experiment, trusting weak hits on a question the memory couldn't answer, serving a stale fact.

→ Read the redacted case study — the real structure, the guards in action, and exactly what's public vs private.

🚀 Quickstart (≈2 minutes, no API key)

git clone https://github.com/GiulioDER/RE-call && cd RE-call
docker compose up -d --wait          # Postgres + pgvector (waits until healthy)
python -m venv .venv && . .venv/bin/activate    # Windows: .\.venv\Scripts\activate
pip install -e ".[fastembed,dev]"
python -m recall.cli demo

Default embedder is local FastEmbed (no key); --embedder hashing is a fully-offline fallback.

🔧 Use it

python -m recall.cli index ./path/to/markdown   # index your own docs
python -m recall.cli search "your question"     # -> hits + gap/freshness flags

Point RECALL_DSN at any Postgres to use your own database.

Code, not just prose. The engine is content-agnostic — point it at source and it chunks on def / class boundaries, so natural-language questions land the exact function:

$ python -m recall.cli index ./src --glob "**/*.py"   # your codebase
$ python -m recall.cli code                            # demo: search RE-call's OWN source
indexed 42 code chunks from 16 files

[ok] query='where is reciprocal rank fusion implemented?'
  0.805  recall/retriever.py  'def _rrf(rankings: list[list[str]], k: int = 60) -> dict[str, float]:…'

[ok] query='how are embeddings stored in postgres?'
  0.789  recall/store.py      'class PgVectorStore:     """The single, production-grade vector store:…'

[ok] query='how does cross-encoder reranking reorder hits?'
  0.878  recall/rerank.py     'class CrossEncoderReranker:     """Reorder hits by cross-encoder relev…'

🔌 Use it with Claude (MCP)

Expose memory to Claude Code or Claude Desktop as three tools — recall_search, recall_index, recall_stats — so the agent queries its memory before it acts:

pip install -e ".[fastembed,mcp]"
python -m recall_mcp.server        # stdio server

The self-recall pattern: Claude calls recall_search before proposing an idea; if a closed decision surfaces (and it isn't a gap_warning), it backs off instead of re-litigating.

→ Full guide: config for Claude Code + Desktop, the three tools, and a real redacted loop  ·  example agent: examples/self_recall_agent.py.

🧪 Reproduce the evaluation

pip install -e ".[fastembed,rerank,eval]"
make eval        # -> results/RESULTS.md + the charts above

The Voyage cloud row appears when VOYAGE_API_KEY is set (shell env, or a gitignored .env).

🧱 Tests

docker compose up -d --wait
pytest -v      # integration tests hit the real pgvector container — no mock DB

License

MIT.