Mnemosure

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An AI memory layer that says "I don't know" when it doesn't, and cites its source when it does.

Across many sessions of AI-assisted work, two failures compound: the assistant forgets decisions that were made, and it hallucinates ones that were not. Mnemosure is a source-grounded memory layer that attacks both.

Its core claim: it does not invent what it cannot remember, and it does not drop what it remembers.

One API key (OpenRouter) drives the whole pipeline — pick any chat, embedding, and rerank model you like (Claude, GPT, Qwen, …), or compute embeddings locally with no key at all.

What it does

• Stores durable facts from a conversation — decisions, changes, failures, established facts — and throws away the chatter.

• Links memories over time: when a new decision overrides an old one, the old one is marked superseded; the reason for a change is linked back to the failure that caused it (because).

• Recalls with a confidence level and citations. When the evidence overrides an old memory, the answer corrects the old fact instead of repeating it. When there is no evidence, it answers "not in the record" instead of guessing.

Every answer comes back as one of three confidence levels — certain / vague / unknown — with the source of each cited memory.

Related MCP server: Enzan

Architecture

flowchart TB
    MCP["MCP server · stdio<br/>recall · remember · list_memories"]
    WEB["Demo web · FastAPI<br/>/ask · /memories · /results"]

    subgraph Ingest["Ingest (remember)"]
        direction TB
        S["Session text"] --> EX["Extract · flash chat model<br/>decision / change / failure / fact"]
        EX --> EMB1["Embed · bge-m3 · 1024d"]
        EMB1 --> LINK["Link associations<br/>supersedes: cosine ≥ 0.35 → flash verdict<br/>because: failure, cosine ≥ 0.15 → flash is_cause"]
        LINK --> STORE[("memories.json<br/>(JSON warehouse)")]
    end

    subgraph Recall["Recall (recall)"]
        direction TB
        Q["Query"] --> EMB2["Embed query"]
        EMB2 --> COS["Cosine top-6<br/>superseded included"]
        COS --> RR["Rerank (optional)<br/>top score under floor → 'unknown'"]
        RR --> EXP["Associative expand<br/>supersedes / because · 2 hops"]
        EXP --> ANS["Answer · brain chat model · temp 0<br/>confidence + answer + citations"]
    end

    MCP --> S
    MCP --> Q
    WEB --> Q
    STORE -. retrieve .-> COS
    STORE -. expand .-> EXP

Ingest (mnemosure/memory/store.py): a session is passed to the flash chat model, which extracts only what will matter later. Each memory is embedded, then two kinds of association are drawn — a lexical prefilter (cosine similarity) proposes candidates and the flash model makes the final call, so nothing is linked on surface similarity alone. Failures are never superseded (lessons are kept forever).

Recall (mnemosure/memory/recall.py): the query is embedded and the top candidates are pulled — including superseded ones, because correcting a stale belief requires finding it first. The rerank model re-orders by relevance; if even the best hit is too weak, the answer is unknown rather than a guess. The surviving seeds are expanded two hops along their supersedes/because links, and the brain model composes the final answer grounded only in that evidence (temperature 0). Broad "summarize everything" questions bypass top-K and ground on all active memories so nothing is dropped.

Models (via OpenRouter — swap freely)

All model calls go through one OpenAI-compatible gateway (default: OpenRouter). Defaults:

Point any of them at any OpenRouter model id (anthropic/claude-sonnet-5, openai/gpt-…, …). Two more switches:

• MNEMOSURE_RERANK=off — skip the rerank call entirely; ranking and the honesty gate then use the first-pass cosine scores. Cheaper, slightly less precise.

• MNEMOSURE_BASE_URL — use a different OpenAI-compatible gateway instead of OpenRouter (then set MNEMOSURE_API_KEY).

The honesty-gate thresholds (MNEMOSURE_RERANK_FLOOR, MNEMOSURE_COSINE_FLOOR) default to values calibrated for the default models above — if you swap the rerank or embedding model, re-check them on your own data.

The API key is read only from the environment (or .env) and is never hard-coded. Defaults live in mnemosure/config.py (the single source of truth).

Install

pip install mnemosure          # the core product: memory library + MCP server

Then provide your OpenRouter key and run the MCP server:

export OPENROUTER_API_KEY=sk-or-...
mnemosure-mcp                  # stdio MCP server

• Where memories are stored: an installed copy starts with an empty warehouse at ~/.mnemosure/memories.json. Override the directory with MNEMOSURE_DATA_DIR.

• The pip package ships only the product (config, llm, mcp_server, reembed, memory/). The web demo and evaluation harness live in this repository (clone it to run them).

Local embeddings (no key for the index)

pip install "mnemosure[local]"
export MNEMOSURE_EMBED_PROVIDER=local

Embeddings are then computed on your machine with fastembed (default model: intfloat/multilingual-e5-large, 1024-dim). The model weights are not bundled — they are downloaded once from Hugging Face on first use and cached (works offline afterwards; on a restricted network, pre-place the model in the fastembed cache dir). Chat and rerank still use the API key.

Switching embedding models (migration)

Vectors from different embedding models don't mix — the warehouse records which model built it, and Mnemosure refuses to run on a mismatch instead of failing silently. To switch models (including api↔local), re-embed once:

python -m mnemosure.reembed                      # default warehouse
python -m mnemosure.reembed path/to/memories.json

Quick start (from source)

# 1) create and activate a project virtual environment
python3 -m venv .venv
source .venv/bin/activate

# 2) install dependencies
pip install -r requirements.txt

# 3) provide your OpenRouter key
cp .env.example .env        # then edit .env and set OPENROUTER_API_KEY

# 4) verify all four model roles are reachable
python scripts/check_models.py

Run the demo

The repository ships with precomputed demo snapshots (under data/scenarios/<key>/), so the demo works right after cloning:

python scripts/run_demo.py      # → http://127.0.0.1:8000

It includes two scenarios — a pre-market trading bot and a SaaS subscription-pricing revamp — that you can switch between. Each scenario also lets you expand its source conversations, so you can confirm the memories were extracted from real multi-session chats, not hardcoded. The memory warehouse and the before/after evaluation panels render straight from the snapshot — no API key needed to browse them. Only /ask (live grounded recall) calls the models and therefore needs a key. To regenerate a scenario's snapshot from scratch (consumes credits):

python scripts/gen_demo_data.py            # all scenarios (only missing ones)
python scripts/gen_demo_data.py pricing    # a specific scenario

Use it as an MCP server

Mnemosure exposes the memory layer over the Model Context Protocol, so any MCP-capable agent (Claude Desktop, Claude Code, Codex, …) can call it as a tool.

mnemosure-mcp                       # if installed via pip
python -m mnemosure.mcp_server      # equivalent, from a source checkout

Register it in your agent's .mcp.json (or equivalent). After pip install mnemosure, the console command is enough:

{
  "mcpServers": {
    "mnemosure": {
      "command": "mnemosure-mcp",
      "env": { "OPENROUTER_API_KEY": "sk-or-..." }
    }
  }
}

The .mcp.json above works with any MCP client. Claude Code users can skip the hand-editing and register it in one line:

claude mcp add mnemosure --env OPENROUTER_API_KEY=sk-or-... -- mnemosure-mcp

Zero-install with uv — run it straight from PyPI without pip install (the console script mnemosure-mcp differs from the package name mnemosure, so pass --from):

{
  "mcpServers": {
    "mnemosure": {
      "command": "uvx",
      "args": ["--from", "mnemosure", "mnemosure-mcp"],
      "env": { "OPENROUTER_API_KEY": "sk-or-..." }
    }
  }
}

Running from a source checkout instead of an install? Use "command": "/abs/path/.venv/bin/python", "args": ["-m", "mnemosure.mcp_server"], and add "PYTHONPATH": "/abs/path/to/repo" so the package is importable regardless of the launcher's working directory.

Tools:

Note: the server itself calls the configured models for classification, recall, and grounding — it is agent-agnostic but assumes an API key is present (via env or .env).

Evaluation approach

Quality is measured by labeling each answer's behavior — accurate / omission / hallucination / noise / honest — alongside our three-way confidence (certain / vague / unknown), rather than a single opaque score. The whole pipeline (extraction, supersession judgment, scoring) runs at temperature 0 for reproducibility. The demo serves a fixed snapshot so results are stable across viewings.

See mnemosure/evaluation/ (harness.py, judge.py, label.py, baseline.py, answer_key.py).

Project structure

mnemosure/
  config.py           # gateway, models, key loading — single source of truth
  llm.py              # the only gateway to models (chat / embed / rerank, local embeddings)
  mcp_server.py       # MCP tools: recall · remember · list_memories (stdio)
  reembed.py          # one-shot warehouse re-embedding (embedding-model migration)
  memory/
    store.py          # ingest: extract → embed → link supersedes/because → save
    recall.py         # recall: embed → rerank → associative expand → grounded answer
    forget.py         # forgetting / relevance handling
    storage.py        # JSON-file memory warehouse (records its embedding model)
    models.py         # Memory / Association / Source dataclasses
  evaluation/         # harness · judge · label · baseline · answer_key
  demo/
    server.py         # FastAPI: /ask · /memories · /results · /sessions · /scenarios
    index.html        # single-page demo UI (scenario switcher + source-transcript viewer)
    scenarios.py      # scenario registry (sessions + answer keys + snapshot paths)
    sample_sessions.py# fictional scenarios (trading bot, subscription pricing) for demo & eval
scripts/              # check_models · gen_demo_data · run_demo · demo_* helpers
data/scenarios/<key>/ # per-scenario memories.json + results.json (demo snapshots, committed)

Deployment

The demo ships with a Dockerfile (single container, source + precomputed snapshots; the API key is injected at run time, never baked in). It runs on any Docker host. Quick local run:

docker build -t mnemosure-demo .
docker run -p 8000:8000 -e OPENROUTER_API_KEY=sk-or-... mnemosure-demo
# → http://127.0.0.1:8000  (health: /health)

Upgrading from 0.2.x (breaking changes)

0.3.0 replaces the Qwen Cloud (DashScope) integration with a single OpenAI-compatible gateway (default: OpenRouter):

• Key: DASHSCOPE_API_KEY is no longer read — set OPENROUTER_API_KEY (or MNEMOSURE_BASE_URL + MNEMOSURE_API_KEY for another gateway).

• Confidence tokens in recall responses are now English: certain / vague / unknown (were 확실/어렴풋/모름).

• Warehouses built with 0.2.x (text-embedding-v4 vectors) must be re-embedded once: python -m mnemosure.reembed.

License

MIT.