Show HN: Karellen-rr-MCP – MCP server that gives LLMs rr reverse debugging

karellen-rr-mcp is an MCP server that lets AI coding assistants use rr for reverse debugging. Instead of the usual cycle of adding debug output, rebuilding, and re-running, the LLM records a failing test with rr, then replays it with full forward and reverse execution via GDB/MI -- stepping backwards from crashes, setting watchpoints on corrupted variables, and reverse-continuing to find the exact write that caused the problem.

Supports breakpoints, hardware watchpoints, state inspection (backtrace, locals, evaluate, memory, registers, source), checkpoints for instant time-travel within a trace, and configurable timeouts for large binaries.

I've been testing it with Claude Code on MariaDB Server and it works remarkably well -- the LLM can debug segfaults and subtle logic errors that would otherwise require extensive manual investigation.

Requires Linux x86-64, rr, and GDB.

pip install karellen-rr-mcp.