Pensyve MCP Server

Pensyve

Universal memory runtime for AI agents. Framework-agnostic, protocol-native, offline-first.

Without memory

User: "I prefer dark mode and use vim keybindings"
Agent: "Got it!"

[next session]

User: "Update my editor settings"
Agent: "What settings would you like to change?"
User: "I ALREADY TOLD YOU"

With Pensyve

# Session 1 — agent stores the preference
p.remember(entity=user, fact="Prefers dark mode and vim keybindings", confidence=0.95)

# Session 2 — agent recalls it automatically
memories = p.recall("editor settings", entity=user)
# → [Memory: "Prefers dark mode and vim keybindings" (score: 0.94)]

Your agent stops being amnesiac. Decisions, patterns, and outcomes persist across sessions — and the right context surfaces when it's needed.

Why Pensyve

What you need	How Pensyve solves it
Agent forgets everything between sessions	Three memory types — episodic (what happened), semantic (what is known), procedural (what works)
Agent can't find the right memory	8-signal fusion retrieval — vector similarity + BM25 + graph + intent + recency + frequency + confidence + type boost
Agent repeats failed approaches	Procedural memory — Bayesian tracking on action→outcome pairs surfaces what actually works
Memory store grows unbounded	FSRS forgetting curve — memories you use get stronger, unused ones fade naturally. Consolidation promotes repeated facts.
Need cloud signup to get started	Offline-first — SQLite + ONNX embeddings. Works on your laptop right now. No API keys needed.
Need to scale to production	Postgres backend — feature-gated pgvector for multi-node deployments. Managed service at pensyve.com.
Only works with one framework	Framework-agnostic — Python, TypeScript, Go, MCP, REST, CLI. Drop-in adapters for LangChain, CrewAI, AutoGen.

Install

pip install pensyve          # Python (PyPI)
npm install @pensyve/sdk     # TypeScript (npm)
go get github.com/major7apps/pensyve/pensyve-go/v3@latest  # Go

Or use the MCP server directly with Codex, Claude Code, Cursor, or any MCP client — see MCP Setup.

Quick Start

pip install pensyve

Episode: your agent remembers a conversation

import pensyve

p = pensyve.Pensyve()
user = p.entity("user", kind="user")

# Record a conversation — Pensyve captures it as episodic memory
with p.episode(user) as ep:
    ep.message("user", "I prefer dark mode and use vim keybindings")
    ep.message("agent", "Got it — I'll remember your editor preferences")
    ep.outcome("success")

# Later (even in a new session), the agent recalls what happened
results = p.recall("editor preferences", entity=user)
for r in results:
    print(f"[{r.score:.2f}] {r.content}")

Recall grouped: feed an LLM reader without rebuilding session blocks

When the consumer of recalled memories is another LLM (the dominant "memory for an AI agent" pattern), recall_grouped() returns memories already clustered by source session and ordered chronologically — ready to format as session blocks in a reader prompt.

import pensyve

p = pensyve.Pensyve()
groups = p.recall_grouped("How many projects have I led this year?", limit=50)

# Each group is one conversation session — feed it to a reader directly.
for i, g in enumerate(groups, start=1):
    print(f"### Session {i} ({g.session_time}):")
    for m in g.memories:
        print(f"  {m.content}")

No more manual OrderedDict clustering, no more reordering by date string, no more boilerplate every consumer has to reinvent.

Remember: store an explicit fact

p.remember(entity=user, fact="Prefers Python over JavaScript", confidence=0.9)

Procedural: the agent learns what works

# After a debugging session that succeeded:
ep.outcome("success")

# Pensyve tracks action→outcome reliability with Bayesian updates.
# Next time a similar issue comes up, recall surfaces the approach that worked.

Consolidate: memories stay clean

p.consolidate()
# Promotes repeated episodic facts to semantic knowledge
# Decays memories you never access via FSRS forgetting curve

Building from source

<details> <summary>Prerequisites and build steps</summary>

• Rust 1.88+, Python 3.10+ with uv
• Optional: Bun (TypeScript SDK), Go 1.21+ (Go SDK)

git clone https://github.com/major7apps/pensyve.git && cd pensyve
uv sync --extra dev
uv run maturin develop --release -m pensyve-python/Cargo.toml
uv run python -c "import pensyve; print(pensyve.__version__)"

</details>

Interfaces

Pensyve exposes its core engine through multiple interfaces — use whichever fits your stack.

Python SDK

Direct in-process access via PyO3. Zero network overhead.

import pensyve

p = pensyve.Pensyve(namespace="my-agent")
entity = p.entity("user", kind="user")

# Remember a fact
p.remember(entity=entity, fact="User prefers Python", confidence=0.95)

# Recall memories (flat list)
results = p.recall("programming language", entity=entity)

# Recall memories clustered by source session — the canonical entry point
# for "memory as input to an LLM reader" workflows.
groups = p.recall_grouped("programming language", limit=50)

# Record an episode
with p.episode(entity) as ep:
    ep.message("user", "Can you fix the login bug?")
    ep.message("agent", "Fixed — the session token was expiring early")
    ep.outcome("success")

# Consolidate (promote repeated facts, decay unused memories)
p.consolidate()

MCP Server

Works with Claude Code, Cursor, and any MCP-compatible client.

cargo build --release --bin pensyve-mcp

{
  "mcpServers": {
    "pensyve": {
      "command": "./target/release/pensyve-mcp",
      "env": { "PENSYVE_PATH": "~/.pensyve/default" }
    }
  }
}

Tools exposed: recall, remember, episode_start, episode_end, forget, inspect, status, account

Claude Code Plugin

Full cognitive memory layer for Claude Code with 7 commands, 4 skills, 2 agents, and 6 lifecycle hooks.

Install from the marketplace:

/plugin marketplace add major7apps/pensyve
/plugin install pensyve@major7apps-pensyve
/reload-plugins

The plugin does not bundle an MCP server config — auth method and backend are user choices. Add an mcpServers.pensyve entry to your ~/.claude/settings.json (user-level) or .claude/settings.json (project-level). Pick one:

Pensyve Cloud — API key (recommended):

export PENSYVE_API_KEY="psy_your_key_here"

{
  "mcpServers": {
    "pensyve": {
      "type": "http",
      "url": "https://mcp.pensyve.com/mcp",
      "headers": {
        "Authorization": "Bearer ${PENSYVE_API_KEY}"
      }
    }
  }
}

Pensyve Cloud — OAuth (browser sign-in):

{
  "mcpServers": {
    "pensyve": {
      "type": "http",
      "url": "https://mcp.pensyve.com/mcp"
    }
  }
}

Pensyve Local (self-hosted, no API key):

Build the MCP binary first (see Install), then:

{
  "mcpServers": {
    "pensyve": {
      "command": "pensyve-mcp",
      "args": ["--stdio"]
    }
  }
}

Note: Use headers with Authorization: Bearer for remote MCP (HTTP transport). Use the top-level env block (Claude Code MCP schema) for local stdio servers that read environment variables at startup.

Plugin contents:
├── 7 slash commands   /remember, /recall, /forget, /inspect, /consolidate, /memory-status, /using-pensyve
├── 4 skills           session-memory, memory-informed-refactor, context-loader, memory-review
├── 2 agents           memory-curator (background), context-researcher (on-demand)
└── 6 hooks            SessionStart, Stop, PreCompact, UserPromptSubmit, PostToolUse (Write/Edit, Bash)

See integrations/claude-code/README.md for full documentation.

Codex Plugin

First-class working memory for OpenAI Codex with a plugin manifest, bundled MCP server config, hooks, skills, /pensyve, and $pensyve skill invocation.

Add this repo as a Codex plugin marketplace, then install Pensyve:

codex plugin marketplace add major7apps/pensyve
codex plugin add pensyve@pensyve-codex

For local development from a checkout, use codex plugin marketplace add /path/to/pensyve/integrations/codex-plugin instead.

Set your API key for the bundled MCP server:

export PENSYVE_API_KEY="psy_your_key_here"

The plugin bundles integrations/codex-plugin/.mcp.json, so Codex can load the Pensyve MCP server without copying a project config file. Use /skills, $pensyve, or /pensyve for explicit memory work, or let the bundled hooks and instructions prompt Codex to recall before substantive project decisions. @pensyve is documented as a text-level compatibility convention; true native Codex @-mention dispatch still needs platform support.

See integrations/codex-plugin/README.md for the manual fallback and local-stdio setup.

REST API

Rust/Axum gateway serving REST + MCP with auth, rate limiting, and usage metering.

cargo build --release --bin pensyve-mcp-gateway
./target/release/pensyve-mcp-gateway  # listens on 0.0.0.0:3000

# Remember
curl -X POST http://localhost:3000/v1/remember \
  -H "Content-Type: application/json" \
  -d '{"entity": "seth", "fact": "Seth prefers Python", "confidence": 0.95}'

# Recall
curl -X POST http://localhost:3000/v1/recall \
  -H "Content-Type: application/json" \
  -d '{"query": "programming language", "entity": "seth"}'

# Recall, clustered by source session (canonical for LLM-reader workflows)
curl -X POST http://localhost:3000/v1/recall_grouped \
  -H "Content-Type: application/json" \
  -d '{"query": "How many books did I buy?", "limit": 50, "order": "chronological"}'

Endpoints: GET /v1/health, POST /v1/recall, POST /v1/recall_grouped, POST /v1/remember, POST /v1/entities, DELETE /v1/entities/{name}, POST /v1/inspect, GET /v1/stats, PATCH /v1/memories/{id}, DELETE /v1/memories/{id}

TypeScript SDK

HTTP client with timeout, retry, and structured errors.

import { Pensyve } from "@pensyve/sdk";

const p = new Pensyve({
  baseUrl: "http://localhost:3000",
  timeoutMs: 10000,
  retries: 2,
});
await p.remember({ entity: "seth", fact: "Likes TypeScript", confidence: 0.9 });
const memories = await p.recall("programming", { entity: "seth" });

// Session-grouped recall — feed an LLM reader without rebuilding session blocks.
const { groups } = await p.recallGrouped("how many projects did I lead?", {
  limit: 50,
  order: "chronological",
});
for (const g of groups) {
  console.log(`### Session ${g.sessionId} (${g.sessionTime})`);
  for (const m of g.memories) console.log(`  ${m.content}`);
}

Go SDK

Context-aware HTTP client with structured errors.

import pensyve "github.com/major7apps/pensyve/pensyve-go/v3"

client := pensyve.NewClient(pensyve.Config{BaseURL: "http://localhost:3000"})
ctx := context.Background()
client.Remember(ctx, "seth", "Likes Go", 0.9)
memories, _ := client.Recall(ctx, "programming", nil)

CLI

cargo build --bin pensyve-cli

# Recall memories (default output is JSON; use --format text for human-readable)
./target/debug/pensyve-cli recall "editor preferences" --entity user

# Show namespace status with memory counts
./target/debug/pensyve-cli status

# Show stats
./target/debug/pensyve-cli stats

# Inspect an entity
./target/debug/pensyve-cli inspect --entity user

Environment Variables

Pensyve uses the following environment variables across its components:

Core

Variable	Default	Description
PENSYVE_PATH	~/.pensyve/<namespace>	SQLite database directory
PENSYVE_NAMESPACE	default	Memory namespace name
RUST_LOG	pensyve=info	Tracing filter (e.g. debug, pensyve=debug,hyper=warn)
PENSYVE_ALLOW_MOCK_EMBEDDER	false	Fall back to mock embedder if real models unavailable (eager startup only, i.e. with PENSYVE_EAGER_EMBEDDER=1)
PENSYVE_EAGER_EMBEDDER	false	Load the ONNX model at startup instead of on first use

Gateway / REST API

Variable	Default	Description
PENSYVE_API_KEYS	(empty)	Comma-separated valid API keys (standalone mode)
PENSYVE_VALIDATION_URL	(none)	Remote endpoint for API key validation
PENSYVE_RATE_LIMIT	300	Max requests per minute per API key
HOST	0.0.0.0	Server bind address
PORT	3000	Server bind port

Cloud / Managed Service

Variable	Default	Description
PENSYVE_API_KEY	(none)	Cloud API key for remote mode
PENSYVE_REMOTE_URL	http://localhost:8000	Remote server URL
DATABASE_URL	(none)	Postgres connection string
REDIS_URL	(none)	Redis for caching, rate limiting, daily quotas

Quotas (managed service)

Variable	Default	Description
PENSYVE_MAX_NAMESPACES	unlimited	Max namespaces per account
PENSYVE_MAX_MEMORIES	unlimited	Max total memories per account
PENSYVE_MAX_RECALLS_PER_MONTH	unlimited	Max recall operations per month
PENSYVE_MAX_STORAGE_BYTES	unlimited	Max storage bytes per account

Optional Features

Variable	Default	Description
PENSYVE_TIER2_ENABLED	false	Enable Tier 2 LLM extraction
PENSYVE_TIER2_MODEL_PATH	(none)	Path to GGUF model file
PENSYVE_OTEL_ENDPOINT	(none)	OpenTelemetry collector URL

Architecture

Data Model

Namespace (isolation boundary)
  └── Entity (agent | user | team | tool)
        ├── Episodes (bounded interaction sequences)
        │     └── Messages (role + content)
        └── Memories
              ├── Episodic  — what happened (timestamped, multimodal content type)
              ├── Semantic  — what is known (SPO triples with temporal validity)
              └── Procedural — what works (action→outcome with Bayesian reliability)

Retrieval Pipeline

1. Embed query via ONNX (Alibaba-NLP/gte-base-en-v1.5, 768 dims)
2. Classify intent — Question/Action/Recall/General (keyword heuristics)
3. Vector search — cosine similarity against stored embeddings
4. BM25 search — FTS5 lexical matching
5. Graph traversal — petgraph BFS from query entity
6. Fusion scoring — weighted sum of 8 signals (vector, BM25, graph, intent, recency, access, confidence, type boost)
7. Cross-encoder reranking — BGE reranker on top-20 candidates
8. FSRS reinforcement — retrieved memories get stability boost

Project Structure

pensyve/
├── pensyve-core/       Rust engine (rlib) — storage, embedding, retrieval, graph, decay, mesh, observability
├── pensyve-python/     Python SDK via PyO3 (cdylib)
├── pensyve-mcp/        MCP server binary (stdio, rmcp)
├── pensyve-cli/        CLI binary (clap)
├── pensyve-ts/         TypeScript SDK (bun) — timeout, retry, PensyveError
├── pensyve-go/         Go SDK — context-aware HTTP client
├── pensyve-wasm/       WASM build — standalone minimal in-memory Pensyve
├── pensyve_server/       Shared Python utilities — billing, extraction
├── integrations/       All integrations — IDE plugins, framework adapters, code harnesses
│   ├── claude-code/    Claude Code plugin (commands, skills, agents, hooks)
│   ├── vscode/         VS Code sidebar extension
│   ├── openclaw-plugin/ OpenClaw native memory plugin (TypeScript)
│   ├── opencode-plugin/ OpenCode native memory plugin (TypeScript)
│   ├── cursor/         Cursor MCP setup guide
│   ├── cline/          Cline MCP setup guide
│   ├── windsurf/       Windsurf MCP setup guide
│   ├── continue/       Continue MCP setup guide
│   ├── vscode-copilot/ VS Code Copilot Chat MCP setup guide
│   ├── langchain/      LangChain/LangGraph Python (PensyveStore + legacy PensyveMemory)
│   ├── langchain-ts/   LangChain.js/LangGraph.js TypeScript (PensyveStore)
│   ├── crewai/         CrewAI (PensyveStorage + standalone PensyveCrewMemory)
│   └── autogen/        Microsoft AutoGen multi-agent memory
├── tests/python/       Python integration tests
├── benchmarks/         LongMemEval_S evaluation + weight tuning
├── website/            Astro + Tailwind static site for pensyve.com
└── docs/               Architecture, roadmap, design specs, implementation plans

Development

First-Time Setup

# Install dependencies (creates .venv automatically)
uv sync --extra dev

# Build the native Python module (required before running any Python code)
uv run maturin develop --release -m pensyve-python/Cargo.toml

# Verify the module loads
uv run python -c "import pensyve; print(pensyve.__version__)"

Note: The pensyve Python package is a native Rust extension built with PyO3. You must run uv run maturin develop before pytest or any Python import of pensyve, otherwise you will get ModuleNotFoundError: No module named 'pensyve'.

Build & Test

make build      # Compile Rust + build PyO3 module
make test       # Run all tests (Rust + Python)
make lint       # clippy + ruff + pyright
make format     # cargo fmt + ruff format
make check      # lint + test (CI gate)

To run test suites individually:

cargo test --workspace                                       # Rust tests
uv run maturin develop --release -m pensyve-python/Cargo.toml  # Build PyO3 module first
uv run pytest tests/python/ -v                               # Python tests
cd pensyve-ts && bun test                                    # TypeScript tests
cd pensyve-go && go test ./...                               # Go tests

Additional SDKs

cd pensyve-ts && bun test          # TypeScript (38 tests)
cd pensyve-go && go test ./...     # Go (17 tests)
cd pensyve-wasm && cargo check     # WASM (standalone)

Benchmarks

# Synthetic recall smoke test (planted facts, no external dataset required)
python benchmarks/synthetic/run.py --generate --evaluate --verbose

Competitive Landscape

What you need	Pensyve	Mem0	Zep	Honcho
Works offline, no cloud required	Yes — SQLite, runs on your laptop	No — cloud API	No — requires server	No — cloud API
Agent learns from outcomes	Yes — procedural memory tracks what works	No	No	No
Finds memories by meaning	8-signal fusion (vector + BM25 + graph + intent + 4 more)	Vector only	Vector + temporal	Vector only
Memories fade naturally	FSRS forgetting curve with reinforcement	No — manual cleanup	Basic TTL	No
Multi-turn conversation capture	Episodes with outcome tracking	Basic	Yes	Yes
Framework agnostic	Python, TypeScript, Go, MCP, REST, CLI	Python SDK	Python/JS	Python
Claude Code / Cursor / VS Code	Native plugins + MCP	No	No	No
Production-ready at scale	Postgres + pgvector (feature-gated)	Yes	Yes	Yes
Open source	Apache 2.0	Yes	Partial	Yes

License

Apache 2.0