Peon Mem MCP Server

🧠 Peon — a memory brain for your AI coding agents

Local-first, hierarchical, self-improving memory for Claude Code, Codex, and any MCP client.

Your AI forgets everything between sessions. Peon doesn't. It records your sessions, uses an LLM to consolidate them into typed beliefs, and injects the relevant ones back into every prompt. It runs as a daemon on your machine, and nothing leaves it.

        PEON GLOBAL BRAIN            ← user-level facts & preferences, inherited everywhere
       /        |         \
  project A  project B  project C    ← rooted child brains (.peon/ in each project)

Why Peon

• Hierarchical brains. One global parent brain holds who you are, your rules, and your tools. Each project gets an isolated child brain. Every injection carries both.
• Two memory layers, honestly measured. Consolidated beliefs (decisions, preferences, facts, artifacts) give you the gist. An episodic verbatim layer recovers the exact details that lossy summaries drop. On LongMemEval, raw-episodic recall scored 61% where belief-only scored 17%.
• Automatic capture and injection. Claude Code hooks record messages and events, then inject a query-ranked memory block (with an ⚠ MOST RELEVANT headline) into every prompt. You never have to remember to save anything.
• Cost-gated consolidation. An LLM distills sessions into beliefs only once enough new memory accumulates. It can supersede, merge, and flag conflicts. Nothing is destructively deleted.
• Hybrid retrieval. Lexical and semantic RRF fusion, MMR diversity, reinforcement, and recency. Query embeddings are cached to disk, so repeat prompts cost nothing.
• The Neural Universe. A live monitor at localhost:3737/monitor renders every belief as a star. Projects are galaxies, search makes matches flare, and autonomous curation pulses.
• A daily self-audit (STL). Peon checks itself every day: what it recorded, what it injected, what failed, what consolidation did. Then it files a report with a verdict.
• Eval-gated development. A committed results ledger (git SHA, qrels, and brain fingerprint per row) means retrieval changes are proven, not asserted. Negative results stay documented.
• Local-first and locked down. Plain JSONL you can read, a loopback-only daemon with DNS-rebinding protection, secret redaction at the injection boundary, and path-traversal guards.

The live monitor: 18k real beliefs rendered as stars. Type to make matching beliefs flare; click one to inspect it.

Ask the field: typing "wulver cluster" makes 400+ matching beliefs flare while the rest dim, and the camera flies to them.

Why "Peon"?

The name comes from Indian offices. Every office had a peon, the person who walked desk to desk all day: collect a file from this table, note who needs what, carry it to the next table, remember where everything is. He wasn't the boss or the star, but the whole office quietly ran on him. Nothing moved without him, and he never forgot where anything was.

That's this framework, with AI. Peon walks between your sessions and your projects. It collects what happened at one desk (a session), files it in the right cabinet (a project brain), carries the relevant papers to the next desk before you ask (injection), and keeps the master ledger upstairs (the global brain). Quiet clerk. Perfect memory. The office runs on him.

How Peon differs from existing memory tools

The short version: mem0 and Zep are memory platforms for products you build. Peon is memory for the coding agents you already use. It plugs into Claude Code or Codex in about five minutes, and you can watch it think and audit every number it claims.

Quickstart

Requirements: Node 20+, macOS or Linux. An OpenRouter API key is recommended (consolidation + semantic embeddings); without one Peon still works lexical-only.

One line:

npm install -g peon-mem && peon-mem install

(no Node? curl -fsSL https://raw.githubusercontent.com/VineetV2/peon-mem/main/install.sh | bash)

The guided setup asks four things:

1. Where your global brain lives (default: ~/Library/Application Support/Peon)
2. Which LLM: OpenRouter (one key, any model) · OpenAI · Anthropic · Ollama (100% local & free) · or skip
3. Installs the daemon as an auto-start service (launchd on macOS, systemd user unit on Linux)
4. Detects your AI apps and wires the MCP server (plus hooks for Claude Code) into the ones you pick. Auto-configured: Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, Windsurf, VS Code (Copilot MCP), Zed, LM Studio. Detected with in-app instructions: ChatGPT Desktop, Perplexity Desktop. Every touched config gets a .peon-backup.

That builds the package, starts the daemon as a service, wires your Claude Code hooks + MCP server (with a backup of your settings), and writes a config template. Then add your key to ~/Library/Application Support/Peon/.env and open the monitor. peon-mem install --dry-run shows every action first; peon-mem uninstall reverses it (memory data is never touched).

Or manually:

git clone https://github.com/VineetV2/peon-mem && cd peon-mem
npm install && npm run build
node bin/peon-mem.mjs install --dry-run   # inspect, then run without --dry-run

Create .env in the repo root:

OPENROUTER_API_KEY=sk-or-...
PEON_PROCESSING_MODEL=google/gemini-2.5-flash-lite   # cheap + good enough (measured)
PEON_EMBEDDING_MODEL=openai/text-embedding-3-small

Start the daemon (the installer prints a launchd/systemd recipe, or just):

node dist/daemon-cli.js              # serves 127.0.0.1:3737

Then wire your agent (the installer prints these filled in for your paths):

• Claude Code: add the hook to ~/.claude/settings.json (SessionStart / UserPromptSubmit / SessionEnd → scripts/claude-peon-hook.mjs) and the MCP server (dist/index.js).
• Codex / any MCP client: register dist/index.js as a stdio MCP server; 16 tools (start_session, get_context, search_memory, record_message, process_memory, …).

Open http://127.0.0.1:3737/monitor and watch your brain grow.

How it works

1. Record. Hooks stream messages, events, and tool calls into <project>/.peon/raw/ (append-only).
2. Consolidate. Past a size gate, an LLM turns the session delta into typed belief records in .peon/brain/memories.jsonl (importance/confidence scores, entities, provenance pointers), reconciling against existing beliefs: supersede, merge, conflict-flag. Recoverable, never deleted.
3. Retrieve + inject. On every prompt, beliefs are ranked (RRF lexical+semantic, MMR, reinforcement) and injected alongside episodic verbatim matches and inherited global beliefs.
4. Self-curate. A background brain pass reinforces recalled beliefs, compresses stale clusters, and resolves duplicates. Every action is logged and undoable.
5. Self-audit (STL). A daily job reports what was recorded, what was injected, what went wrong, and whether consolidation behaved, with serve-latency telemetry and a health verdict.

Full install (copy-paste)

1. Daemon (always-on, macOS launchd)

node scripts/install-peon.mjs           # prints everything below filled in for YOUR paths

Or manually — ~/Library/LaunchAgents/com.peon.daemon.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0"><dict>
  <key>Label</key><string>com.peon.daemon</string>
  <key>ProgramArguments</key><array>
    <string>/opt/homebrew/bin/node</string>
    <string>/ABSOLUTE/PATH/TO/peon/dist/daemon-cli.js</string>
  </array>
  <key>RunAtLoad</key><true/>
  <key>KeepAlive</key><true/>
</dict></plist>

launchctl load ~/Library/LaunchAgents/com.peon.daemon.plist
curl http://127.0.0.1:3737/health        # → {"ok":true}

Linux: the installer writes ~/.config/systemd/user/peon-mem.service and enables it. Manual equivalent: systemctl --user enable --now peon-mem.service, plus loginctl enable-linger $USER so it survives logout. (Linux support is young — issue #1 tracks real-machine reports.)

2. Claude Code — hooks (auto capture + injection)

Merge into ~/.claude/settings.json (replace the path):

{
  "hooks": {
    "SessionStart": [{ "hooks": [{ "type": "command",
      "command": "node /ABSOLUTE/PATH/TO/peon/scripts/claude-peon-hook.mjs" }] }],
    "UserPromptSubmit": [{ "hooks": [{ "type": "command",
      "command": "node /ABSOLUTE/PATH/TO/peon/scripts/claude-peon-hook.mjs" }] }],
    "SessionEnd": [{ "hooks": [{ "type": "command",
      "command": "node /ABSOLUTE/PATH/TO/peon/scripts/claude-peon-hook.mjs" }] }]
  }
}

3. Claude Code — MCP server (search/inspect tools)

claude mcp add peon -- node /ABSOLUTE/PATH/TO/peon/dist/index.js

4. Codex / any MCP client

~/.codex/config.toml:

[mcp_servers.peon]
command = "node"
args = ["/ABSOLUTE/PATH/TO/peon/dist/index.js"]
[mcp_servers.peon.env]
PEON_DAEMON_URL = "http://127.0.0.1:3737"

Codex has no hooks, so add usage rules to ~/.codex/AGENTS.md telling it to call start_session + get_context at session start and record_message for durable facts (example block in docs/).

5. Verify

curl "http://127.0.0.1:3737/context?projectPath=$PWD&query=test"   # JSON context
open http://127.0.0.1:3737/monitor                                  # the Neural Universe

Start a Claude Code session in any project, say something decision-shaped, and end the session. Within a minute the monitor shows the belief. The next session injects it.

MCP tools exposed

start_session · record_message · record_event · end_session · get_context · search_memory · inspect_brain · build_injection · query_projects (cross-project search) · quality_report · remember_global · search_global_memory · import_global_memory · evaluate_project · process_memory · maybe_process_memory

Uninstall

launchctl unload ~/Library/LaunchAgents/com.peon.daemon.plist
# remove the hook entries + MCP server from your agent config
# your memory stays in <project>/.peon/ and ~/Library/Application\ Support/Peon/ — plain files, delete when ready

Troubleshooting / FAQ

• No injection appearing? curl http://127.0.0.1:3737/health; check the hook is registered (run any prompt in claude, then look at the monitor's Systems page for the request).
• 431 errors on huge prompts? Handled. The hook caps the retrieval query at 2k chars.
• No OpenRouter key? Everything still runs; retrieval is lexical + episodic only (semantic ranking and consolidation need a model). PEON_EMBEDDING_MODE=ollama works too.
• Cost? Consolidation is gated (default: fires per ~6k new chars, around cents/day with flash-lite). Query embeddings are cached to disk, so repeats are free.
• Multiple machines? Brains are plain files in your repos. Commit .peon/ if you want memory to travel (redact first: the raw layer contains session text).
• Is my data sent anywhere? Only consolidation/embedding calls to your configured model provider. No telemetry, no cloud store. The daemon rejects non-loopback callers.

Configuration (env)

Project brains

• A brain lives in <project>/.peon/ as human-readable JSONL and markdown. Commit it or ignore it; your choice (.gitignore ships ignoring it).
• .peon/root marks a brain boundary. New brains are born rooted, so a parent directory can never swallow a project's memory.
• The global brain lives in ~/Library/Application Support/Peon/global/ (macOS).

Using Peon with NO AI at all

Some people want a memory system that never calls a model: no API keys, no local LLM, no embeddings. Peon supports that. Pick skip in the install wizard, or set two env vars in <memory-home>/.env:

PEON_AI_MODE=off
PEON_EMBEDDING_MODE=off

The pipeline looks like this without a model. Hooks still capture everything you do into <project>/.peon/raw/ as plain JSONL. As each event arrives, rule-based extraction files it into readable brain files: a line that starts with "we decided" or "always use" lands in decisions.md, preferences land in preferences.md, file paths land in artifacts.md. No model reads it; it's pattern matching, and you can open the files to see exactly what it caught. At your next session start, the hook asks the daemon for context, the daemon ranks those records by keyword match, recency, and importance, and injects the best ones into your prompt. The only step that disappears entirely is consolidation, the nightly LLM pass that compresses raw history into deduplicated beliefs. Without it your memory is a well-indexed journal instead of a distilled one. Search still finds things; nothing summarizes them.

What still works (all of it deterministic code, no model anywhere):

• Capture. Hooks record every prompt, tool call, and session event to plain JSONL in <project>/.peon/raw/.
• Real-time brain files. Decisions, preferences, open questions, and artifacts are written live to readable .md files by rule-based extraction as events arrive.
• Injection. Session-start context comes from those real-time files, query-focused and budgeted, same as always.
• Search. Lexical retrieval (RRF over keyword rank, recency, importance, and type priors). No embeddings needed. This is the same degrade path the semantic stack falls back to, so it gets exercised constantly.
• Episodic recall. Verbatim what-was-said lookup is lexical by design, so it is unaffected.
• Monitor UI, token tracking, cross-project search, backups. All model-free.

What you give up: consolidation (raw events are never distilled into deduplicated beliefs, so memory grows as an append-only journal), semantic search (paraphrased queries need shared keywords), automatic entity extraction, and stale-shadow demotion (it compares embeddings).

Two escape hatches if you want curation without external AI:

1. process_memory accepts a pre-built aiResult. The coding agent you already run (Claude Code, Codex) can do the distillation itself in-session and hand Peon the structured result. Memory stays curated, and Peon itself never spends a token.
2. Everything is plain JSONL/Markdown on disk. You can edit beliefs by hand or through the monitor's memory endpoints, and Peon backs up before every mutation.

Measured: does memory actually save tokens?

A/B test with real claude -p sessions: one question per session, same repo, same model. ON means Peon hooks active (memory injected at session start). OFF means PEON_DISABLED=1, so the agent falls back to reading files. 20 questions across procedures, past results, decisions, and current-state facts; 15 clean ON/OFF pairs survived tooling issues. Token counts come from Claude Code's own session transcripts.

Answer quality, graded against repo ground truth: 8 ties, 1 clear Peon win, 5 baseline wins, 1 where both were weak. The Peon win is the interesting one. A rule that was only ever stated in a conversation (a professor's citation policy, from an email) got "no such rule found" from the baseline; Peon recited it exactly. Conversation-borne knowledge has no file to grep.

Honest caveats: the test repo has unusually good docs (a maintained research log), which makes the baseline strong, and most repos aren't like that. n=15 is small. Questions were picked to have known answers, not sampled from real usage. The test also exposed two real bugs in Peon itself: a stale superseded belief outranking the newer truth, and token rows getting lost when consolidation outlived the hook timeout. Both are fixed (stale-shadow demotion at retrieval; usage logged before consolidation).

Honesty section

Peon's development is eval-gated and keeps its negative results. An associative entity graph was built, measured (−2.9% Recall@10), and turned OFF by default. Consolidation is lossy by design; that's why the episodic layer exists and is regression-tested. The eval harness and committed ledger (npm run eval) let you verify retrieval changes on your own brain.

Security

• The daemon binds 127.0.0.1 only and rejects non-loopback Host/Origin headers (DNS-rebinding defense).
• Secrets (API keys, tokens, JWTs) are redacted at the injection boundary.
• Path traversal is guarded. Writes use per-project locks and atomic tmp+rename, with automatic backups before anything destructive-adjacent. Nothing is hard-deleted.

License

MIT © Vineet Vora

Contributing — I'd love your help

Peon is built and maintained by one person, and I'm open to help making it better. Issues, PRs, ideas, criticism of the architecture, or just telling me where it broke on your machine: all of it is useful.

Where help would matter most right now:

• Windows & Linux support. The daemon install is macOS launchd today. The systemd and Task Scheduler equivalents need real users to test them.
• More agent integrations. The wizard covers 11 apps, but hooks-level capture (like the Claude Code integration) for Codex, Cursor, and others would make memory richer everywhere.
• Retrieval quality. The eval harness (npm run eval) makes experiments cheap: better consolidation prompts, smarter staleness handling, local embedding models worth defaulting to.
• Benchmarks. Run the token A/B on your repo and share the numbers, especially where Peon loses. Negative results are first-class here.
• Docs and onboarding. If the README or the wizard confused you, that confusion is a bug report.

Open an issue at github.com/VineetV2/peon-mem/issues or send a PR directly.

Rules of the house: every retrieval/quality change ships with a test and an eval-ledger run (npm run eval); negative results get documented, not deleted; nothing may hard-delete user memory. npm test must stay green.