SpecLock: Open Source Constraint Engine for AI Coding Agents
SpecLock is an open source constraint engine that adds active enforcement to AI coding agents. While Claude Code's native memory can remember constraints, SpecLock actively blocks violations with semantic conflict warnings.
How SpecLock Works
SpecLock operates as an MCP server with 19 MCP tools. When you set a constraint like "never modify auth files," if Claude tries to violate it—even 10 sessions later—the action gets blocked. The system uses three key techniques:
- Synonym expansion across 15 groups
- Negation detection
- Destructive action flagging
This semantic understanding means that "remove the login endpoints" correctly triggers against a constraint about "never modify auth files."
Compatibility and Availability
SpecLock works with multiple platforms:
- Bolt.new (npm mode, no MCP needed)
- Lovable
- Cursor
- Windsurf
The tool is free, open source, and available on GitHub. The developer built it over several months after experiencing frustration with AI tools ignoring constraints.
📖 Read the full source: r/ClaudeAI
👀 See Also
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Phaselock: An AI Agent Control System Inspired by Parenting Techniques
Phaselock is an open-source Agent Skill that implements four control mechanisms for AI coding agents: explicit gates before action, immediate feedback on mistakes, constrained choices, and mechanical rule enforcement. It works with Claude Code, Cursor, Windsurf, and any tool supporting hooks.
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