dejasearch 0.3.0

Semantic search MCP server for Claude Code sessions

deja

Semantic search over your Claude Code session history. Ask questions about past conversations by meaning, not just keywords.

deja is an MCP server that indexes Claude Code JSONL sessions and provides hybrid search (vector + full-text) directly from Claude Code.

How it works

~/.claude/projects/*/        deja index         index.db
     *.jsonl           ──────────────►    (SQLite + vec + FTS5)
                        embeddings
                                           │
                                           │  deja serve (MCP stdio)
                                           ▼
                                      Claude Code
                                    "search past sessions"

1. Index — parses JSONL session files, extracts conversation turns, embeds with multilingual-e5-small, stores in SQLite
2. Serve — MCP server opens the index and answers search queries via stdio transport

Search combines vector KNN (semantic similarity) and FTS5 (keyword matching) via Reciprocal Rank Fusion.

Install

git clone https://github.com/CynepMyx/deja.git
cd deja
python -m venv .venv
.venv/Scripts/pip install -e .        # Windows
# .venv/bin/pip install -e .          # Linux/macOS

First run downloads the embedding model (~117 MB).

Usage

Build the index

deja index              # incremental — only new/changed files
deja index --reindex    # full rebuild

Scans all ~/.claude/projects/*/*.jsonl files.

Add to Claude Code

Add to ~/.claude.json under mcpServers:

"deja": {
    "type": "stdio",
    "command": "/path/to/deja/.venv/Scripts/deja.exe",
    "args": ["serve"],
    "env": {
        "PYTHONUNBUFFERED": "1"
    }
}

Restart Claude Code — deja will appear as a connected MCP server.

MCP Tools

Tool	Description
search	Hybrid semantic + keyword search across all sessions
get_session_chunks	Get indexed chunks for a session (not raw messages)

search parameters:

• query (string) — what to search for
• limit (int, default 10) — max results
• project (string, optional) — filter by project
• date_from / date_to (string, optional) — ISO date range

Auto-indexing (optional)

Index automatically when a Claude Code session ends. Add a Stop hook to ~/.claude/settings.json:

"hooks": {
    "Stop": [
        {
            "matcher": "",
            "hooks": [
                {
                    "type": "command",
                    "command": "/path/to/deja/.venv/bin/deja index"
                }
            ]
        }
    ]
}

On Windows with Git Bash, wrap in a shell script:

#!/bin/bash
DEJA="/path/to/deja/.venv/Scripts/deja.exe"
[ -f "$DEJA" ] && "$DEJA" index >/dev/null 2>&1 &

"command": "bash /path/to/deja-index.sh"

PID lock prevents concurrent indexers — safe with multiple sessions.

Stack

• fastembed — ONNX embeddings (intfloat/multilingual-e5-small, 384-dim)
• sqlite-vec — vector KNN search in SQLite
• SQLite FTS5 — full-text keyword search
• FastMCP — MCP server framework

Performance

Metric	Value
Incremental index	< 30 sec
Search latency (warm)	< 500 ms
First search (cold start)	< 5 sec
RAM (search)	~150 MB
RAM (indexing)	~300 MB

Development

pip install -e ".[dev]"
pytest

License

MIT