@hypercubs/mcp-server

MCP server for DRC (Deterministic Replay Compute). Connects AI coding agents to DRC's execution versioning system for deterministic capture, replay, comparison, and verification across software behavior.

Prerequisites

Install the DRC CLI:

npm install -g @hypercubs/drc

Initialize your project:

cd your-project
drc init --service your-service

Setup

Claude Code

Add to your MCP config (~/.claude/mcp.json or project .mcp.json):

{
  "mcpServers": {
    "drc": {
      "command": "npx",
      "args": ["@hypercubs/mcp-server"]
    }
  }
}

Or run inside Claude Code:

/mcp add drc npx @hypercubs/mcp-server

Cursor

Add to your MCP config (Cursor Settings → MCP):

{
  "mcpServers": {
    "drc": {
      "command": "npx",
      "args": ["@hypercubs/mcp-server"]
    }
  }
}

Windsurf

Add to your MCP config:

{
  "mcpServers": {
    "drc": {
      "command": "npx",
      "args": ["@hypercubs/mcp-server"]
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "drc": {
      "command": "npx",
      "args": ["@hypercubs/mcp-server"]
    }
  }
}

Available tools

Once connected, your AI agent can use these DRC tools:

| Tool | Description | |------|-------------| | trace | Show the causal chain of an execution: events, dependencies, and errors | | analyze | Run the analysis pipeline: baseline replay, divergence detection, classification | | search | List captured executions with filters for service, time range, and state | | diff | Compare two executions and identify the earliest divergence | | bisect | Binary-search events to find the minimal set that produces an error | | blast-radius | Scan all executions for a bug pattern and show aggregate impact | | replay | Replay an execution under controlled conditions | | counterfactual | Run what-if modifications against a captured execution | | inject | Apply virtualized state changes (clock, files, env, DB, cache) | | regress | Promote a captured execution into a regression test | | chaos | Apply chaos mutations across all virtualization layers | | fix | Confirm a fixed codebase resolves captured failures |

Example prompts

Once connected, try asking your agent:

• "Use DRC to trace the last failed execution"
• "Replay execution exec_abc123 and show me where it diverges from the baseline"
• "Search for all executions in the last 24 hours that had errors"
• "Diff these two executions and find the earliest divergence"
• "Bisect this failure to find the minimal reproduction"

Environment variables

| Variable | Description | |----------|-------------| | DRC_BIN | Override the path to the drc binary (optional) |

How it works

This package is a thin wrapper that finds the drc binary on your system and launches it as an MCP server over stdio transport.

License

See LICENSE in the DRC repository.