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0CompactMem

Persistent memory MCP server with OS-style demand paging, kswapd-style eviction, and mlock pinning. Multi-agent shared SQLite store with BM25 + FTS5 retrieval, importance scoring, and capacity-aware reclaim. 5 tools: `memory_lookup`, `pin_memory`, `unpin_memory`, `memory_stats`,…

knowledge-memorysqlitegithubaiagent
By soolaugust
0Updated 2 weeks agoPython

Installation

uvx --from git+https://github.com/soolaugust/0CompactMem memory-os

Configuration

{
  "mcpServers": {
    "0CompactMem": {
      "command": "npx",
      "args": ["-y", "0CompactMem"]
    }
  }
}

How to use

  1. Run the installation command above (if needed)
  2. Open your Claude Code settings file (~/.claude/settings.json)
  3. Add the configuration to the mcpServers section
  4. Restart Claude Code to apply changes
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0CompactMem

Zero compaction. Infinite memory. For Claude Code and every LLM agent.

Your AI never forgets — no more "context compacted" interruptions.

Python SQLite Tests License Discussions

English · 中文

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One-line install via Claude Code:

/install-plugin github:soolaugust/0CompactMem

The problem: context compaction kills your flow

If you use Claude Code, you know this pain:

⚠️ Auto-compact: conversation is approaching context limit...

Every time this happens, your AI loses track of decisions, constraints, and hard-won context. You re-explain. It re-learns. Hours of accumulated understanding — gone in one compaction event.

And if you run multiple agents? They can't share what they've learned. Each one starts from zero.

This isn't a model limitation. It's a missing infrastructure layer.


The solution: persistent memory that survives compaction

0CompactMem gives your AI agents persistent, retrievable memory that lives outside the context window. When compaction happens, nothing is lost — because the important stuff was never only in the context window to begin with.

The result: zero effective compaction. Your AI retains every decision, constraint, and lesson across sessions, across compactions, across agents.

How it works

You speak
  → 0CompactMem retrieves relevant memories → injects into context
  → AI responds with full context
  → Session ends → decisions and insights auto-extracted → persisted
  → Compaction happens? No problem — memories survive outside the window
  → Next session starts → working set restored automatically

The whole pipeline runs inside Claude Code hooks. There is no manual memory management.


Why "0CompactMem"?

What others seeWhat actually happens
"Context compacted"Critical knowledge already persisted to memory store
New session startsWorking set auto-restored in <100ms
Multiple agents runningAll share the same memory — no re-explanation
Constraint decided 3 weeks agoPinned in memory, guaranteed never evicted

Zero compaction impact. Zero context loss. Zero re-explanation.


Under the hood: OS memory management for AI

The secret sauce? We didn't invent new algorithms. We borrowed what the Linux kernel has been doing for 40 years:

OS concept0CompactMem equivalent
RAM (working space)Context window — what the AI sees right now
Disk (persistent storage)Knowledge base — facts that survive across sessions
Demand pagingOn-demand retrieval — fetch relevant memories at the right moment
mlockHard / soft pinning — guarantee a constraint is never evicted
kswapd watermarksCapacity-aware eviction under pressure
CRIU checkpoint / restoreSession snapshots — pause and resume seamlessly
Process schedulingMulti-agent coordination — many agents, one knowledge base
kworker thread poolAsync extraction — I/O off the critical path

How is this different from mem0 / Letta / Zep?

0CompactMemmem0Letta (MemGPT)Zep
Design metaphorOS memory subsystemVector storeAgent runtimeTemporal graph
Zero-compact guarantee✅ pinned memories survive
Multi-agent shared✅ native, single store⚠️ via API
MCP-native✅ first-class
Single-file deploy✅ SQLite, no service❌ needs server❌ needs server❌ needs server
Demand-paging retrieval✅ explicitimplicitimplicitimplicit
Eviction policy✅ kswapd + DAMONTTL onlyrecencyrecency + decay
Pin / mlock semantics

TL;DR. If you're tired of context compaction wiping your AI's memory, and you want a solution that's pip install, runs as a sidecar on a laptop, shares between several Claude Code / Cursor / custom agents, and never loses a pinned constraint — 0CompactMem is built for that.


Performance at a glance

MetricValue
Retrieval latency (P50, hot path)~0.1 ms (540x faster than the 54 ms subprocess baseline)
Recall@3 vs baseline+147%
Cross-session recall94.2%
Token cost per call~44 tokens injected, +256 tokens net ROI (avoided re-explanation)
Test suite3,500+ tests across retrieval, eviction, MCP, privacy filter

Quick start

One-line install (recommended).

/install-plugin github:soolaugust/0CompactMem

Manual install.

git clone https://github.com/soolaugust/0CompactMem
cd 0CompactMem
pip install -e .
mkdir -p ~/.claude/memory-os

Detailed Claude Code hook configuration, daemon management, and troubleshooting live in docs/SETUP.md.


Architecture

Three layers:

  1. Hooks — sit at the Claude Code syscall boundary (SessionStart, UserPromptSubmit, Stop, PostToolUse) and call into the store.
  2. Store — single SQLite file (WAL mode) with FTS5 full-text index, behind a unified VFS interface (store.py / store_vfs.py / store_criu.py).
  3. Daemons & IPC — persistent retriever daemon (Unix socket), async extractor pool (kworker-style), cross-agent notify bus.

For the full layered diagram, on-disk schema, and the rationale behind each subsystem, see docs/ARCHITECTURE.md. For the comprehensive OS-and-cognitive-science primitive mapping, see docs/DESIGN_PHILOSOPHY.md.


Roadmap

  • Distributed 0CompactMem — cgroup-style multi-agent quotas, network-replicated stores
  • Adaptive watermarks — eviction tuning that follows observed agent behavior
  • arXiv preprint — formal evaluation against mem0 / Letta / Zep
  • Per-chunk embedding routing — different models for code vs prose

What landed already (1,051+ tuning iterations, eight major capability rounds) is summarized in CHANGELOG.md. Pain points it has resolved along the way are in docs/PROBLEMS_SOLVED.md.


Testing

# stable test subset
python3 -m pytest tests/test_agent_team.py tests/test_chaos.py -q

Coverage: per-session DB isolation, concurrent-write safety, cross-agent IPC delivery, extractor-pool queue semantics, CRIU checkpoint validation, goals-progress idempotency.


Dependencies

No GPU. No external API. Everything runs locally.

DependencyPurpose
Python 3.12+Core runtime
SQLite (built-in)Store + FTS5 full-text index
nc, flockDaemon socket + single-instance startup

Paper

📄 Beyond Eviction: Full OS Memory Semantics for LLM Agent Persistence (PDF, 8 pages)

Technical paper describing the complete OS→agent-memory mapping: demand paging, kswapd, DAMON, mlock, CRIU, kworker, and shared memory.

Citation

@software{su2026compactmem,
  title = {0CompactMem: Full OS Memory Semantics for LLM Agent Persistence},
  author = {Su, Zhidao},
  year = {2026},
  url = {https://github.com/soolaugust/0CompactMem}
}

Contributing

Each subsystem hides behind a clean VFS interface, so components are testable in isolation. Issues, design proposals, and pull requests are welcome — see the Discussions tab for design questions, and please run the test subset above before submitting a PR.


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Context compaction is the #1 productivity killer in Claude Code. 0CompactMem makes it a non-event.

English · 中文

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View source on GitHub