sqlew

Design decisions, remembered by SQL — an MCP server for AI agents

What is sqlew?

The Problem

Every AI coding session starts from scratch. Your agent doesn't remember that you chose PostgreSQL over MongoDB last week, or that the team agreed on a specific API versioning strategy. Without persistent memory, agents repeat mistakes, contradict earlier decisions, and waste tokens re-discovering context.

The Solution

sqlew stores your architectural decisions in a structured SQL database. When a new session starts, the AI agent queries past decisions in milliseconds — not by reading through scattered Markdown files, but through efficient SQL lookups with metadata, tags, and similarity detection.

┌─────────────────────────────────────────────────────────────┐
│  Before sqlew                 │  After sqlew                │
│───────────────────────────────│─────────────────────────────│
│  Session 1: "Use PostgreSQL"  │  Session 1: "Use PostgreSQL"│
│  Session 2: "Use MongoDB?"    │    → decision recorded      │
│  Session 3: "Use PostgreSQL"  │  Session 2: query → got it  │
│  (same debate, every time)    │  Session 3: query → got it  │
│                               │    (instant recall)         │
└─────────────────────────────────────────────────────────────┘

sqlew is built on the Model Context Protocol (MCP), so it works with any MCP-compatible AI coding tool.

This software does not send any data to external networks. We NEVER collect any data or usage statistics.

Features

• Structured Records — Decisions stored as relational data with metadata, tags, layers, and version history
• Fast Queries — 2-50ms retrieval via SQL, even with thousands of decisions
• Duplicate Detection — Three-tier similarity scoring (0-100) prevents redundant decisions
• Constraint Tracking — Architectural rules and principles as first-class entities
• Auto-Capture — Hooks automatically record decisions from Plan Mode (Claude Code, Codex, Grok Build, and Hermes via sqlew-plugin)
• Session Context Injection — Recent decisions and active constraints injected at session start (Claude Code, Hermes, Codex partial; not Grok Build — see matrix)
• Multi-Database — SQLite (default), PostgreSQL, MySQL/MariaDB, or Cloud
• Git Worktree Ready — Each worktree shares the same context database

Harness compatibility

Not every feature works the same on every client. Grok Build uses passive hooks (no stdout injection), so session context and plan-mode hook enforcement are skill-based only (◎).

✓ full · △ partial · ◎ skills only · ✎ manual MCP · — not available

Full matrix (hooks, Other harness column, fallbacks): Harness Compatibility

For Teams (sqlew.io)

Connect to sqlew.io for team-shared decisions:

Step 1: Get your API key

Visit sqlew.io and save your API key:

# ~/.config/sqlew/.sqlew.env (shared across all projects)
SQLEW_API_KEY=your-api-key

Step 2: Configure each project

# .sqlew/config.toml
[database]
type = "cloud"

[project]
name = "your-project-name"

Benefits:

• All team members share the same decision database
• Works seamlessly with Git worktree workflows
• No local database setup required

Performance

Use Cases

• Architecture Evolution — Document major decisions with full context and alternatives considered
• Pattern Standardization — Establish coding patterns as constraints, enforce via AI code generation
• Cross-Session Continuity — AI maintains context across days/weeks without re-reading docs
• Multi-Agent Coordination — Multiple AI agents share architectural understanding
• Onboarding Acceleration — New AI sessions instantly understand project history

Documentation

Upgrade Guides

• Migrating to SaaS — Export local data to sqlew.io cloud

MCP Tools

8 action-based tools: decision, constraint, project, suggest, help, example, use_case, queue

All tools support action: "help" for documentation. The project tool targets a project per call for desktop AI agents (Claude Desktop, Hermes Desktop) — see Shared Database.

Support

Support development via GitHub Sponsors.

Version

Current version: 5.3.0

See CHANGELOG.md for release history.

What's New in v5.3.0:

• Hermes support — Plan-to-ADR via sqlew-plugin .hermes-plugin bundle (hermes plugins install sqlew-io/sqlew-plugin/.hermes-plugin)
• Hook normalization — Hermes pre_tool_call / pre_llm_call payloads mapped to canonical Claude-shaped events and tools
• Every-turn plan guidance — on-prompt injects FULL/SHORT context via Hermes pre_llm_call ({"context":"..."})
• .hermes/plans/ — Plan files written by the Hermes plan skill are tracked for decision extraction

License

Apache License 2.0 — Free for commercial and personal use. See LICENSE for details.

Links

• npm package
• GitHub
• Issues
• Model Context Protocol

Built with MCP SDK, better-sqlite3, and TypeScript.

Quick Start

1. Install

npm install -g sqlew

2. Setup

Choose the setup that matches your environment. Each client has its own install and uninstall steps.

Claude Code (Plugin)

Install:

claude plugin marketplace add sqlew-io/sqlew-plugin
claude plugin install sqlew

Configures MCP server, Skills (Plan Mode guidance), and Hooks (automatic decision capture).

Uninstall:

claude plugin remove sqlew

Codex CLI (Plugin)

Install:

codex plugin marketplace add sqlew-io/sqlew-plugin
codex plugin install sqlew --source sqlew-plugin

After install, open /hooks in Codex and trust the bundled sqlew hooks. Enable Plan Mode with collaboration_modes = true under [features] in your Codex config.

Do not duplicate skills in ~/.codex/skills/ or add [mcp_servers.sqlew] to config.toml when using the plugin. See Hooks Guide.

Uninstall:

codex plugin remove sqlew

Grok Build (Plugin)

Install:

grok plugin install sqlew-io/sqlew-plugin --trust
grok plugin update

Configures MCP server, Skills (plan mode guidance), and Hooks (automatic decision capture on exit_plan_mode).

Do not duplicate hooks in ~/.grok/hooks/ or add [mcp_servers.sqlew] to ~/.grok/config.toml. See Hooks Guide.

Uninstall:

grok plugin remove sqlew

Hermes (Plugin)

Requires sqlew >= 5.3.0. Hermes uses a separate plugin bundle (.hermes-plugin/), not the Claude/Codex plugin manifest.

Install:

hermes plugins install sqlew-io/sqlew-plugin/.hermes-plugin
hermes plugins enable sqlew

Merges MCP + shell hooks into ~/.hermes/config.yaml and copies planning skills to ~/.hermes/skills/. See Hermes Hooks Guide for wire-protocol details and manual config.yaml setup.

Uninstall:

hermes plugins remove sqlew

If you merged hooks manually before using the plugin, also remove mcp_servers.sqlew and sqlew hooks: entries from ~/.hermes/config.yaml. Skills under ~/.hermes/skills/sqlew-* are not removed automatically.

Other harness (MCP only)

MCP server only — no sqlew-plugin hooks or skills (Cursor, Claude Desktop, custom clients, …). See Harness Compatibility.

Add to .mcp.json in your project root:

{
    "mcpServers": {
        "sqlew": {
            "command": "sqlew"
        }
    }
}

The database (~/.config/sqlew/sqlew-shared.db) and config are auto-created on first run. See Shared Database for details.

3. Just use Plan Mode!

That's it. Every time you create a plan and get user approval, your architectural decisions are automatically recorded.

No special commands needed — just plan your work normally, and sqlew captures the decisions in the background.