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hippocampus-mcp

Personal memory infrastructure for people who use AI agents every day.

hippocampus-mcp ingests your conversation logs from multiple platforms (Claude Code, ChatGPT, claude.ai, Codex CLI) into a PostgreSQL + pgvector database that you run, and exposes them as MCP search tools to any agent session. Your past reasoning, decisions, and debugging sessions stop evaporating when the window closes.

The differentiator is the ghost layer: a separate, opt-in vault where the agent's own accumulated rules and feedback ("last time this failed because...") are synced nightly and become searchable from every project — cross-project agent memory, not just human conversation recall.

The name: the hippocampus is the brain structure that consolidates short-term experience into long-term memory during sleep. This system imitates that loop — daytime sessions accumulate as JSONL, a nightly ingest embeds and persists them, and the next session can recall them.

INGEST                          STORE                      RETRIEVE (MCP)
Claude Code sessions  ─┐
ChatGPT export ZIP    ─┤  parse → scrub → embed   personal.*  ──┐  search_personal_memory
claude.ai export ZIP  ─┼─────────────────────────▶ (your        ├─ search_conversations
Codex CLI history     ─┘                           PostgreSQL)  ├─ list_recent_conversations
                                                                ┘  get_conversation ...
agent memory files    ───  nightly dub (opt-in) ─▶ agent.*    ──── search_ghost_memory

Quick start

Prerequisites: Python 3.11+, a psql client on PATH (Debian/Ubuntu: apt-get install postgresql-client), and either Docker or an existing PostgreSQL with the pgvector extension.

Everything runs on your machine by default — the database is a bundled docker-compose postgres, and hippocampus init sets it up for you.

git clone <this-repo> hippocampus-mcp && cd hippocampus-mcp

# 1. Install the package
pip install .

# 2. First-run setup. Pick "local" for the database (the default), pick an
#    embed backend, optionally provision the ghost layer. init generates
#    the DB password, writes .env (mode 0600), starts the compose postgres,
#    runs migrations, and prints the MCP registration snippet.
hippocampus init

# 3. Semantic search via the bundled local BGE-M3 server (recommended):
#    choose "bge-http" + http://localhost:8086 in init, then bring it up —
#    compose reads the token init wrote into .env (~6 GB model on first start)
docker compose --profile bge up -d

# 4. Verify, then ingest your Claude Code sessions
hippocampus doctor
hippocampus ingest claude-code

Non-interactive minimal install (no embed model — semantic tools stay hidden, and ingest refuses to run, until a backend is configured; vectors are written together with the text, never backfilled silently):

hippocampus init --yes --embed none

If host port 5432 is taken (a host postgres, or a Windows-side listener under WSL2), pass --pg-port <free-port> — compose and the generated PG_URL follow it via .env.

Running the database on a separate server instead? Choose existing at the database prompt (or --db existing) and paste your PostgreSQL URL — see INSTALL.md Path B, and PRIVACY.md for what a remote database implies (your conversation text transits the network; keep it on a private network or behind TLS). Local is the recommended default.

Register the MCP server

Add to ~/.claude/settings.json (or your client's MCP config). The snippet contains no secrets — the server reads .env from its working directory:

{
  "mcpServers": {
    "hippocampus": {
      "command": "/path/to/your/venv/bin/hippocampus-mcp"
    }
  }
}

If your MCP client does not launch servers from the project directory, use the one-line cd && exec wrapper that hippocampus init prints at the end of its run.

Then, from a fresh agent session:

search_personal_memory("that postgres deadlock we debugged")
list_recent_conversations(days=2)
get_conversation("claude_code:<conv-id>")
search_ghost_memory(current_project="my-repo")   # ghost layer, if enabled

Related MCP server: brain-mcp

Ingest sources

Four sources are built in (hippocampus ingest --list):

Every source runs the same pipeline: parse → credential scrub → embed → upsert → verify (the run fails loudly if any ingested message ended up without a vector). Conversations are deduplicated, so re-running an ingest is safe.

After ingest, hippocampus summarize builds per-conversation rollup summaries and segment summaries for long conversations (substrate for summary-level search). It requires an Anthropic API key (ANTHROPIC_API_KEY) and a working embed backend — see PRIVACY.md for exactly what text it sends where.

Semantic search backends

Semantic (vector) search is off until you explicitly choose a backend — there is no silent model download. Three choices at hippocampus init (changeable later in .env):

Details and a decision table: INSTALL.md.

Ghost layer (cross-project agent memory)

Project-local agent memory files can be promoted — via an explicit dual-signal opt-in (frontmatter scope: shared and a line in a human-edited allowlist file) — into a shared vault that any project's session can search through search_ghost_memory. Promotion is default-deny; a content scanner is a third wall behind the two signals.

hippocampus init --ghost provisions the read-only database role it needs. Full user guide: docs/GHOST_LAYER_USER.md.

Privacy

Short version: your full conversation text and its vectors live in your PostgreSQL. Nothing leaves your machine unless you explicitly enable a feature that needs it (Anthropic-backed scoring/summaries, a remote embed endpoint). Credential scrubbing at ingest is best-effort, not a guarantee. Read PRIVACY.md before ingesting anything sensitive.

Support model

This is published as useful infrastructure, not a supported product. It is the actual daily-driver memory system of its author, extracted into an installable shape. Issues and PRs are welcome and handled best-effort; there is no SLA, no roadmap commitments, and APIs may change between minor versions. If it breaks, hippocampus doctor output (which is designed to be safe to paste — no secrets ever appear in it) is the most useful thing to include in a report.

Documentation

• docs/ARCHITECTURE.md — how the pieces fit together (code-grounded overview)

• INSTALL.md — detailed setup: compose vs existing PG, embed backends, migrations, troubleshooting, automation

• PRIVACY.md — what is stored, what leaves the box and when, scrub limits, prompt-injection posture

• docs/GHOST_LAYER_USER.md — ghost layer user guide

• docs/EMBED_CONTRACT.md — the L2-norm / 1024-dim embedding invariant

• docs/SECRETS_HARDENED.md — optional sops-encrypted secrets setup (default is a plain .env, mode 0600)

The operator's own helper scripts (scripts/) and internal design-history notes are kept in the author's private development repo and are not bundled in this release; docs that mention them do so illustratively.