MCP Memory Gateway captures explicit structured feedback from AI coding agents, validates it against a rubric engine, and auto-promotes repeated failures into prevention rules enforced via PreToolUse hooks. Pre-action gates physically block tool calls matching known failure patterns before execution — turning past mistakes into hard constraints rather than suggestions. Supports semantic recall via LanceDB vectors, DPO/KTO export for downstream fine-tuning, and a file watcher bridge for external signal ingestion. Compatible with Claude Code, Codex, Gemini, Amp, Cursor, and OpenCode. Install with `npx mcp-memory-gateway init` or `claude mcp add rlhf -- npx -y mcp-memory-gateway serve`. MIT licensed, open source.