Lex

Episodic Memory & Architectural Policy for AI Agents

Stop losing context. Start building agents that remember.

Quick Start · Documentation · Examples · API Reference · Contributing

📖 What is Lex?

Lex is a TypeScript framework that gives AI agents episodic memory and architectural awareness. It solves the fundamental problem of context loss in long-running development workflows.

The Problem

You're working with an AI coding assistant on a complex feature. You stop for the day. When you return:

• The assistant has no memory of what you were doing
• It can't recall why you made certain architectural decisions
• It doesn't know which modules are safe to modify
• You spend 30 minutes re-explaining context every session

The Solution

Lex provides three capabilities:

1. 📸 Episodic Memory (Frames) — Capture work snapshots with context, blockers, and next actions
2. 🗺️ Spatial Memory (Atlas) — Navigate module dependencies without overwhelming token budgets
3. 🛡️ Architectural Policy — Enforce boundaries, permissions, and deprecation patterns in CI

Result: Your AI assistant recalls exactly where you left off, understands your architecture, and respects your constraints.

🎯 Core Capabilities

🧠 Frames: Work Session Memory

Capture meaningful moments in your development workflow:

lex remember \
  --reference-point "Implementing user authentication" \
  --summary "Added JWT validation to API middleware" \
  --next "Wire up password reset flow" \
  --modules "services/auth,api/middleware" \
  --blockers "Need PermissionService access - forbidden edge in policy" \
  --jira "AUTH-123"

Later, instantly recall:

lex recall "authentication"
# Returns: Your exact context, blockers, next action, and relevant module neighborhood

Learn more about Frames →

🗺️ Atlas Frames: Architectural Context

When you recall a Frame, Lex doesn't dump your entire codebase into context. Instead, it provides an Atlas Frame: the modules you touched plus their immediate neighborhood (dependencies, dependents, permissions).

This "fold radius" approach gives AI assistants exactly the architectural context they need—nothing more, nothing less.

Token efficiency: 10-module project → ~500 tokens (not 50,000)

Learn more about Atlas →

🛡️ Policy Enforcement

Define architectural boundaries as code:

{
  "modules": {
    "ui/components": {
      "owns": ["src/ui/components/**"],
      "mayCall": ["services/auth", "ui/shared"],
      "forbidden": [
        {
          "target": "database/queries",
          "reason": "UI must not access database directly. Use API layer."
        }
      ]
    }
  }
}

Enforce in CI:

lex check merged-facts.json
# ✖ Violation: ui/components → database/queries (forbidden edge)
#   Reason: UI must not access database directly. Use API layer.

Learn more about Policy →

📝 Instructions Generation

Maintain a single source of truth for AI assistant guidance:

# Your canonical instructions live in one place
.smartergpt/instructions/lex.md

# Project them to host-specific files
lex instructions generate
# Creates: .github/copilot-instructions.md, .cursorrules

Benefits:

• Single source → Multiple hosts (Copilot, Cursor, etc.)
• Safe updates via marker system (human content preserved)
• Deterministic output (same input = same output)

Learn more about Instructions →

🚀 Quick Start

Installation

# Install globally (recommended)
npm install -g @smartergpt/lex

# Or locally in your project
npm install @smartergpt/lex

Requires Node.js 20+ (tested through Node.js 22, see .nvmrc)

Lex 2.0.0 is AX-native with structured output (--json), recoverable errors (AXError), and Frame Schema v3 for orchestrator integration. All commands provide both human-readable and machine-parseable output.

Initialize

# Zero-to-value initialization (new in v2.1.0!)
npx @smartergpt/lex init --yes
# Auto-detects project type (Node.js, Python, Rust, Go, etc.)
# Creates:
#   .smartergpt/ - Workspace with prompts, policy, and instructions
#   .github/copilot-instructions.md - IDE instructions with LEX markers
#   .cursorrules - Cursor IDE instructions (if Cursor detected)
#   lex.yaml - Configuration with sensible defaults
#   .smartergpt/lex/memory.db - SQLite database (initialized on first use)
# Shows MCP server configuration guidance
# Idempotent: safe to run multiple times

# Interactive mode (prompts for first Frame)
lex init --interactive

# Generate seed policy from directory structure
lex init --policy
# Scans src/ for TypeScript/JavaScript modules
# Generates .smartergpt/lex/lexmap.policy.json with discovered modules
# Example: src/memory/store/ → memory/store module with src/memory/store/** match pattern

# Force reinitialize (overwrite existing files)
lex init --force

What happens during init:

1. 🔍 Project Detection — Identifies Node.js, Python, Rust, Go, Java, .NET, Ruby projects and frameworks
2. 📝 IDE Setup — Creates .github/copilot-instructions.md and .cursorrules (if Cursor detected) with LEX markers for safe updates
3. ⚙️ Configuration — Generates lex.yaml with defaults based on your project
4. 💾 Database — Initializes SQLite database at .smartergpt/lex/memory.db
5. 📡 MCP Guidance — Shows configuration for VS Code MCP server integration

Capture Your First Frame

lex remember \
  --reference-point "Refactoring payment processing" \
  --summary "Extracted validation logic to PaymentValidator" \
  --next "Add unit tests for edge cases" \
  --modules "services/payment"

Recall Later

lex recall "payment"
# Shows your context, blockers, and architectural neighborhood

Database Maintenance

Keep your memory database optimized and backed up:

# Create a timestamped backup (memory-20251123.sqlite)
lex db backup --rotate 7
# Keeps last 7 backups, stored in .smartergpt/lex/backups/

# Optimize database (rebuild and compact)
lex db vacuum

# Set backup retention via environment variable
export LEX_BACKUP_RETENTION=14  # Keep 14 most recent backups

NDJSON Logging: Lex automatically logs operations to .smartergpt/lex/logs/lex.log.ndjson with structured fields:

• timestamp, level, message, module, operation, duration_ms, metadata, error
• Log files rotate automatically at 100MB
• Logs are silent in test mode unless LEX_LOG_NDJSON=1

That's it! You now have persistent memory for your AI workflows.

Full Quick Start Guide →

MCP Server Integration

Use Lex with any MCP-compatible AI assistant (VS Code, Claude Desktop, etc.):

# Install the MCP wrapper
npm install -g @smartergpt/lex-mcp

# Or run directly
npx @smartergpt/lex-mcp

VS Code Configuration (.vscode/mcp.json):

{
  "servers": {
    "lex": {
      "command": "npx",
      "args": ["@smartergpt/lex-mcp"],
      "env": {
        "LEX_WORKSPACE_ROOT": "${workspaceFolder}"
      }
    }
  }
}

Claude Desktop Configuration:

{
  "mcpServers": {
    "lex": {
      "command": "npx",
      "args": ["@smartergpt/lex-mcp"]
    }
  }
}

The MCP server exposes 11 tools for episodic memory, policy validation, and architectural analysis:

• frame_create, frame_search, frame_get, frame_list, frame_validate
• policy_check, timeline_show, atlas_analyze
• system_introspect, help, hints_get

MCP Server Documentation →

💡 Use Cases

👨‍💻 For Developers

• Preserve context across work sessions with AI coding assistants
• Document architectural decisions with searchable, timestamped snapshots
• Enforce boundaries via CI to prevent policy violations

🤖 For AI Agents

• Recall previous work using natural language search
• Navigate large codebases with token-efficient Atlas Frames
• Respect constraints by checking policy before suggesting changes

👥 For Teams

• Onboard new members by showing architectural history
• Track technical debt with kill patterns and forbidden edges
• Maintain consistency across multi-module projects

📸 See It In Action

Want to see how Lex is used in practice? Check out our dogfooding examples — real Frames from building Lex with Lex.

See how we:

• Use lex recall to resume work after breaks
• Capture context with lex remember at key checkpoints
• Handle blockers and escalations in real development
• Track complexity and turn costs for governance

View Dogfood Examples →

🏗️ Architecture

Lex is built on three pillars:

┌─────────────────────────────────────────────────────────┐
│                    Lex Framework                        │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  📸 Memory Layer (lex/memory)                          │
│  ├─ Frame storage (SQLite)                             │
│  ├─ Search & recall                                     │
│  └─ MCP server integration                             │
│                                                         │
│  🗺️ Atlas Layer (lex/shared/atlas)                     │
│  ├─ Module dependency graphs                           │
│  ├─ Fold radius computation                            │
│  └─ Token-aware context generation                     │
│                                                         │
│  🛡️ Policy Layer (lex/policy)                          │
│  ├─ Boundary definitions                               │
│  ├─ Multi-language scanners                            │
│  └─ CI enforcement                                      │
│                                                         │
└─────────────────────────────────────────────────────────┘

Architecture Details →

📚 Documentation

Getting Started

• Quick Start Guide — Get up and running in 5 minutes
• Installation & Setup — Detailed installation guide
• Core Concepts — Understanding Frames, Atlas, and Policy

Guides

• Mind Palace Guide — Using Frames for episodic memory
• Code Atlas Guide — Spatial memory and architectural context
• Policy Enforcement — Setting up architectural boundaries
• Instructions Generation — Sync AI instructions across IDEs
• CLI Reference — Command-line usage and output modes
• MCP Integration — Using Lex with Model Context Protocol
• OAuth2/JWT Authentication — Multi-user authentication setup

Security

• Security Policy — Security posture and best practices
• OAuth2/JWT Guide — Authentication and user isolation

Advanced

• Architecture Loop — How Frames, Atlas, and Policy interact
• API Reference — TypeScript API documentation
• Limitations — Known constraints and future work
• FAQ — Common questions

Development

• Contributing Guide — How to contribute
• Release Process — Versioning and publishing
• ADRs — Architectural decision records

🔧 API Reference

Lex provides multiple entry points for different use cases:

Core API

import { saveFrame, searchFrames, getDb, closeDb } from '@smartergpt/lex';

const db = getDb(); // Uses .smartergpt/lex/memory.db

await saveFrame(db, {
  referencePoint: 'authentication flow',
  summaryCaption: 'Added password validation',
  statusSnapshot: { nextAction: 'Wire up permission check' },
  moduleScope: ['services/auth', 'services/password'],
  branch: 'feature/auth',
  jira: 'AUTH-123'
});

const results = await searchFrames(db, { referencePoint: 'authentication' });
closeDb(db);

Subpath Exports

Full API Documentation →

🎯 Project Status

Current Version: 2.2.0 (Changelog)

🚀 2.0.0 — AX-Native Release

Lex 2.0.0 is the first stable release with AX (Agent eXperience) as a first-class design principle. This release introduces structured output, recoverable errors, and Frame Schema v3 for AI agent integration.

Ready for:

• ✅ Personal projects and local dev tools
• ✅ Private MCP servers
• ✅ CI/CD policy enforcement
• ✅ Multi-user deployments with OAuth2/JWT
• ✅ Encrypted databases with SQLCipher
• ✅ LexRunner and other orchestrator integrations

2.0.0 Highlights:

• AX Guarantees (v0.1) — Structured output, recoverable errors, reliable memory/recall (AX Contract)
• Frame Schema v3 — Runner fields (runId, planHash, toolCalls) for orchestration (Schema Docs)
• AXError Schema — Structured errors with code, message, context, and nextActions[] for programmatic recovery
• CLI JSON Output — lex remember --json and lex timeline --json with machine-parseable event streams
• Instructions Management — lex instructions CLI for syncing AI instructions across IDEs (Copilot, Cursor, etc.)
• LexSona Socket — Behavioral memory API (recordCorrection/getRules) exported via @smartergpt/lex/lexsona
• Performance — Cached policy module ID lookups for O(1) resolution

LexSona Integration: Lex 2.0.0 provides a public behavioral memory socket (@smartergpt/lex/lexsona) for persona-based workflows. LexSona is a separate private package (v0.2.0+) that consumes this socket to enable offline-capable persona modes. The socket API is stable and documented; LexSona implementation details remain private. Lex itself is persona-agnostic — the socket is a stable integration point for any behavioral engine.

See CHANGELOG v2.0.0 for full release notes.

Quality Metrics

🌟 Why Lex?

Cognitive Architecture for AI Agents

The Challenge: AI coding assistants lose context between sessions. They can't remember what you were working on, why you made certain decisions, or which parts of your codebase are off-limits.

Our Approach: External memory and structured reasoning — the same techniques human experts use to maintain context across complex, long-running projects.

The Components:

• Episodic memory — Lex Frames capture what you were doing, blockers, and next actions
• Spatial memory — Atlas Frames provide token-efficient architectural context
• Policy enforcement — Boundaries and permissions enforced in CI
• Orchestration — LexRunner coordinates multi-PR workflows

Why This Matters:

• Continuity — Pick up exactly where you left off, every time
• Architecture — AI assistants understand your codebase structure
• Guardrails — Prevent violations before they happen
• Accessibility — Works with any LLM that supports MCP

🤝 Contributing

We welcome contributions! Here's how to get started:

1. Read the guides:

   • Contributing Guide
   • Code of Conduct
   • Development Setup

2. Pick an issue:

   • Good first issues
   • Help wanted

3. Submit a PR:

   • Follow commit conventions (imperative mood)
   • Include tests and documentation
   • GPG-sign your commits

Contributing Guide →

📦 Related Projects

• LexRunner — Orchestration for parallel PR workflows

• LexSona (v0.2.0+) — Behavioral persona engine, separate private package Consumes Lex behavioral memory socket (@smartergpt/lex/lexsona) to enable offline-capable persona modes with constraint enforcement. High-level concept: persona-driven workflows without embedding persona logic in Lex core. See Control Stack documentation for conceptual framework (public portions).

📄 License

MIT License — Free for personal and commercial use.

See LICENSE for full text.

🔗 Links

• Documentation: docs/
• Examples: examples/
• npm Package: @smartergpt/lex
• Issues: GitHub Issues
• Discussions: GitHub Discussions

Built with ❤️ by the Lex community

⭐ Star on GitHub · 📦 Install from npm · 💬 Join Discussions

💻 Advanced Topics

TypeScript Build System

Lex uses TypeScript project references for deterministic, incremental builds:

npm run build      # Compile with project references
npm run clean      # Clean build artifacts
npm run typecheck  # Type-check without emitting

Why NodeNext module resolution?

• Source uses .ts files with .js import extensions
• TypeScript resolves imports during compilation
• Emitted .js files work correctly in Node.js ESM
• No confusion between source and build artifacts

Build System Details →

Local CI with Docker

Run CI checks locally without touching GitHub:

npm run local-ci          # Run full CI suite locally
npm run local-ci:nonet    # Run without network access

This uses ci.Dockerfile for local parity with CI checks.

Multi-Language Policy Scanning

While TypeScript scanning is built-in, Python and PHP scanners are available as examples:

# Scan Python codebase
python examples/scanners/python/scan.py src/ > python-facts.json

# Scan PHP codebase
php examples/scanners/php/scan.php src/ > php-facts.json

# Merge with TypeScript facts
lex merge ts-facts.json python-facts.json > merged-facts.json

# Check policy
lex check merged-facts.json

⚠️ Security Note: External scanners execute arbitrary code. Review before use.

Scanner Documentation →

Customizing Prompts & Schemas

Lex uses a precedence chain for configuration:

1. Environment: LEX_CANON_DIR=/custom/canon (highest)
2. Local overlay: .smartergpt/prompts/
3. Package defaults: prompts/ (lowest)

# Customize locally
cp prompts/remember.md .smartergpt/prompts/
vim .smartergpt/prompts/remember.md

# Or use custom directory
LEX_CANON_DIR=/my/custom/canon lex remember ...

Environment Variables

🔐 Database Encryption

Protect your Frame data with SQLCipher encryption:

# Enable encryption for new databases
export LEX_DB_KEY="your-strong-passphrase-here"
lex remember --reference-point "work" --summary "Encrypted!"

# Migrate existing database
lex db encrypt --verify

# Production mode requires encryption
export NODE_ENV="production"
export LEX_DB_KEY="production-passphrase"

Key Features:

• ✅ AES-256 encryption at rest
• ✅ PBKDF2 key derivation (64K iterations)
• ✅ Mandatory in production (NODE_ENV=production)
• ✅ Migration tool with integrity verification

Security Guide →

Environment Configuration →

🧪 Development

Prerequisites

• Node.js: v20+ LTS (tested up to v22, see .nvmrc)
• npm: v10+
• Git: For branch detection

Local Setup

# Clone repository
git clone https://github.com/Guffawaffle/lex.git
cd lex

# Install dependencies
npm ci

# Build
npm run build

# Run tests
npm test

# Local CI (full suite)
npm run local-ci

Project Structure

lex/
├── src/                     # TypeScript source (no .js files)
│   ├── memory/             # Frame storage & MCP server
│   ├── policy/             # Policy enforcement & scanners
│   ├── shared/             # Shared utilities & types
│   └── index.ts            # Main entry point
├── dist/                    # Build output (gitignored)
├── canon/                   # Canonical prompts & schemas
├── docs/                    # Documentation
├── examples/                # Usage examples & optional scanners
├── test/                    # Test suite
└── .smartergpt/            # Local workspace (gitignored)

Running Tests

npm test                     # Run all tests (excludes git tests)
npm run test:coverage       # With coverage report
npm run test:watch          # Watch mode
npm run test:git            # Git integration tests (requires non-interactive signing)

Note: Git tests are quarantined due to mandatory GPG signing in this environment. See test/README.md for details.

Code Quality

npm run lint                # ESLint checks
npm run format              # Prettier formatting
npm run typecheck           # TypeScript validation

Contributing Guide →