---

AI coding sessions close and the experience disappears. ChatGPT threads pile up with nowhere to go. Notes accumulate but never get flagged as stale. exo solves all three.

Ingest ChatGPT exports, PDFs, images, and markdown files. Let LLMs compile raw sessions and conversations into structured knowledge pages. Search everything with hybrid FTS5 + vector search and LLM query expansion. Wire it into Claude Code or Cursor as an MCP server so your AI tools can read and write your brain directly.

Table of Contents

• Install
• Quick start
• Commands
• Configuration
• Page format
• Hybrid search
• AI ingestion
• MCP server
• Lint
• Development

---

Install

bun install -g @guqings/exo

Requires Bun 1.x.

---

Quick start

# Initialize your brain (default: ~/.exo/brain.db)
exo init

# Configure AI provider (OpenAI-compatible)
exo config set embed.api_key sk-...
exo config set embed.base_url https://api.openai.com/v1
exo config set compile.api_key sk-...

# Capture a quick note (no LLM, instant)
exo capture "Redis rate limiting: token bucket at 100 req/s per user"

# Or write a full page
echo '---
title: Redis Rate Limiting
type: concept
tags: [redis, backend]
---
Token bucket at 100 req/s per user. Use INCR + EXPIRE for sliding window.
' | exo put concepts/redis-rate-limiting

# Keyword search
exo search "redis rate limit"

# Hybrid search with AI query expansion (requires embed config)
exo query "how to prevent API abuse"

# Read a page
exo get concepts/redis-rate-limiting

# Open the local Web UI
exo ui

# Wire up to Claude Code / Cursor (one-time)
exo setup-mcp

---

Data flow

flowchart TD
    subgraph Sources["Data Sources"]
        A[Markdown files / dirs]
        B[Quick notes / text]
        C["Claude Code / Copilot / Codex session logs"]
        D[ChatGPT export JSON]
        E["Mixed directory (MD + PDF + images)"]
        F[PDF / image / audio / DOCX]
    end

    subgraph Ingest["Ingestion"]
        I1["exo import / exo sync"]
        I2["exo capture"]
        I3["exo harvest"]
        I4["exo digest / exo import-chatgpt"]
        I5["exo ingest"]
        I6["exo attach / exo describe"]
    end

    subgraph Store["Brain — brain.db"]
        INBOX["📥 inbox (staging area)"]
        CONCEPT["🧠 concept / learning / project (knowledge pages)"]
        FILES["📎 files (binary attachments)"]
    end

    subgraph Pipeline["AI Pipeline"]
        COMPILE["exo compile (LLM: create / update / discard)"]
    end

    subgraph Out["Access"]
        SEARCH["exo search / query"]
        UI["exo ui  (web browser)"]
        MCP["exo serve  (MCP / Claude Code)"]
        EXPORT["exo export"]
    end

    A --> I1 --> CONCEPT
    B --> I2 --> INBOX
    C --> I3 --> INBOX
    D --> I4 --> INBOX
    E --> I5 --> INBOX
    F --> I6 --> FILES --> CONCEPT

    INBOX --> COMPILE --> CONCEPT

    CONCEPT --> SEARCH
    CONCEPT --> UI
    CONCEPT --> MCP
    CONCEPT --> EXPORT

    style INBOX fill:#fef3c7,stroke:#d97706
    style CONCEPT fill:#d1fae5,stroke:#059669
    style COMPILE fill:#ede9fe,stroke:#7c3aed

Key insight: import and sync write directly to knowledge pages (no LLM needed). capture, harvest, digest, and ingest land in the inbox staging area first. Run exo compile to let the LLM distill inbox items into your knowledge graph — it merges related items, creates new concept pages, and discards noise.

Commands

Core

Command	Description
exo init [path]	Create brain.db (default: ~/.exo/brain.db)
exo get <slug>	Read a page as markdown
exo put <slug>	Write or update a page (stdin or --file)
exo delete <slug>	Delete a page
exo list	List pages (--type, --tag, --limit)
exo stats	Brain statistics (page counts, DB size)
exo health	Brain health metrics
exo config	View and set configuration

Search

Command	Description
exo search <query>	FTS5 keyword search (--type, --limit)
exo query <question>	Hybrid search: FTS5 + vector RRF + LLM query expansion

Web UI

Command	Description
exo ui	Start the local web UI (--port, --no-open)

AI Ingestion Pipeline

Command	Description
exo capture [text]	Instantly capture a note to the inbox (no LLM, <100ms)
exo inbox	View the inbox queue (items waiting to be compiled)
exo compile	Run LLM pipeline: inbox items → structured knowledge pages
exo harvest	Harvest learnings from Claude Code / Copilot / Codex session logs
exo ingest <dir>	Ingest a mixed directory into inbox (.md/.txt direct; PDF/image/audio auto-extracted)
exo digest <file>	Import conversations from a ChatGPT export JSON
exo import-chatgpt <dir>	Import a full ChatGPT export directory (conversations + images)

Files & Multimodal

Command	Description
exo attach <slug> <file>	Attach a file to a page (PDF, image, DOCX, audio, video)
exo detach <slug> <file>	Detach a file from a page
exo files	List all files attached to your brain
exo describe [file-slug]	Extract and embed content from files via AI (images, PDFs, DOCX, audio)

Embeddings & Sync

Command	Description
exo embed	Generate vector embeddings for pages (--all, --rebuild)
exo sync <dir>	Sync a directory of markdown files into the brain
exo import <file|dir>	Import a markdown file or directory
exo export	Export pages to markdown files

Knowledge Graph

Command	Description
exo link <from> <to>	Create a cross-reference between two pages
exo unlink <from> <to>	Remove a cross-reference
exo backlinks <slug>	Show pages linking to a slug
exo tag <slug> <tag>	Add a tag
exo untag <slug> <tag>	Remove a tag
exo tags [slug]	List all tags, or tags for a specific page
exo graph <slug>	Traverse the knowledge graph from a slug
exo timeline <slug>	View or add timeline entries for a page
exo versions <slug>	Manage page versions (snapshot, list, revert)

Maintenance

Command	Description
exo lint	Check for stale, orphaned, and low-confidence pages
exo doctor	Run health checks on the database and configuration
exo check-update	Check for a newer version on npm

MCP / Agent

Command	Description
exo serve	Start the MCP stdio server
exo setup-mcp	Auto-configure MCP in Claude Code and Cursor
exo call <tool>	Invoke any MCP tool directly from the CLI
exo tools-json	Print all MCP tool definitions as JSON

---

Configuration

exo reads ~/.exo/config.toml. Use exo config to view and exo config set <key> <value> to edit.

[db]
path = "~/.exo/brain.db"

[embed]
base_url = "https://api.openai.com/v1"
api_key  = "sk-..."
model    = "text-embedding-3-large"

[compile]
base_url = "https://api.openai.com/v1"
api_key  = "sk-..."
model    = "gpt-4o"

[vision]
base_url = "https://api.openai.com/v1"
api_key  = "sk-..."
model    = "gpt-4o"

[ui]
port = 7499

Any OpenAI-compatible provider works (Vercel AI Gateway, Azure OpenAI, Ollama, etc.).

DB path resolution

Priority order:

1. --db <path> flag (per-command override)
2. EXO_DB environment variable
3. db.path in ~/.exo/config.toml
4. Default: ~/.exo/brain.db

# Per-command
exo query "rate limiting" --db ~/work/brain.db

# Shell session
export EXO_DB=~/work/brain.db

---

Page format

Pages use YAML frontmatter. A --- separator (with blank lines around it) splits compiled knowledge from timeline entries.

---
title: Redis Rate Limiting
type: concept
confidence: 9
valid_until: 2027-01-01
tags: [redis, backend, rate-limiting]
sources: [https://redis.io/docs/manual/patterns/]
---

# Redis Rate Limiting

Token bucket at 100 req/s per user. Use INCR + EXPIRE for sliding window.
Lua scripts ensure atomicity across INCR + EXPIRE.

---

## Timeline

- **2024-03-15**: Deployed to production. Token bucket chosen over leaky bucket.
- **2024-06-01**: Switched to sliding window after P99 spike analysis.

Slug prefixes and page types

Prefix	Type
concepts/	concept
learnings/	learning
people/	person
projects/	project
sources/	source

Frontmatter fields

Field	Type	Description
title	string	Page title (required)
type	string	Page type (inferred from slug prefix if absent)
confidence	0–10	How sure you are this is still accurate
valid_until	YYYY-MM-DD	Flag as stale after this date
tags	string[]	Arbitrary labels
sources	string[]	URLs or references

---

Hybrid search

exo query combines three signals via Reciprocal Rank Fusion (RRF):

1. FTS5 keyword search — exact term matching, supports Chinese via LIKE fallback
2. Vector search — cosine similarity on text-embedding-3-large embeddings (requires exo embed)
3. LLM query expansion — rewrites your query into synonyms and related terms before searching

# Full hybrid (requires embeddings)
exo query "how to prevent API abuse"

# Keyword only (no API calls, instant)
exo search "redis rate limit"

# Disable query expansion (faster, exact terms)
exo query "redis INCR EXPIRE" --no-expand

Run exo embed --all after ingesting new content to keep vector search current.

---

AI ingestion

Capture → Compile pipeline

# 1. Capture anything instantly (no LLM, goes to inbox)
exo capture "Bun 1.2 ships native S3 client"
echo "Long note from stdin" | exo capture --title "My Note"

# 2. Check inbox
exo inbox

# 3. Compile inbox → structured knowledge pages (uses LLM)
exo compile
exo compile --yes    # skip confirmations

Harvest from AI session logs

# Harvest Claude Code sessions (default)
exo harvest

# Harvest from all supported tools
exo harvest --source all

# Preview without writing
exo harvest --dry-run

Supported sources: Claude Code, GitHub Copilot CLI, Codex.

Import ChatGPT conversations

# Export from ChatGPT settings → import
exo digest conversations.json

# Full export directory (conversations + images)
exo import-chatgpt ~/Downloads/chatgpt-export/

Attach files

# Attach and describe an image (calls vision API)
exo attach concepts/my-page screenshot.png --describe

# Attach a PDF (auto-extracts and indexes text per page)
exo attach concepts/my-page paper.pdf

# Attach audio with transcription (calls Whisper API)
exo attach concepts/my-page meeting.mp3 --transcribe

# Process all unprocessed attached files
exo describe --all

---

MCP server

exo exposes a Model Context Protocol server so Claude Code and Cursor can read and write your brain directly.

exo setup-mcp   # auto-writes ~/.claude/mcp.json and ~/.cursor/mcp.json

To configure manually in ~/.claude/mcp.json:

{
  "mcpServers": {
    "exo": {
      "command": "exo",
      "args": ["serve"]
    }
  }
}

Available MCP tools: brain_search, brain_query, brain_get, brain_put, brain_list, brain_link, brain_stats, brain_lint_summary, brain_capture, brain_timeline.

---

Lint

exo lint surfaces three classes of issues:

• Stale — valid_until is in the past
• Low confidence — confidence <= 3
• Orphaned — no links in or out, no tags

exo lint           # all issues
exo lint --json    # machine-readable output

---

Development

git clone https://github.com/guqing/exo
cd exo
bun install
bun run dev                    # run from source: bun src/cli.ts
bun run ui:dev -- --db ~/path/to/brain.db
# API on 7499, Vite UI on 5173, /api proxied automatically
bun test ./src/tests/          # run test suite
bun run build                  # compile to single binary → bin/exo

---

License

MIT