chiasmus

An MCP server that gives LLM coding assistants a formal reasoning engine for structural code analysis. Instead of iteratively grepping through files, the LLM makes a single tool call and gets a provably correct answer about reachability, dead code, dependency cycles, or impact analysis.

How it works

The pipeline has four stages:

1. Tree-sitter parsing — source files become typed ASTs with method definitions, call relationships, imports, and exports identified.
2. Prolog fact generation — structural relationships are converted to declarative Prolog facts (e.g., calls(moduleA, funcX, moduleB, funcY).).
3. Rule-based analysis — built-in Prolog rules handle cycle-safe transitive reachability, dead code detection, and dependency analysis.
4. Query execution — Prolog's backtracking engine answers the query exhaustively and returns the result in a single MCP tool response.

This is a neurosymbolic-ai pattern: the LLM handles natural language understanding and decides what to ask, the symbolic solver handles exhaustive graph traversal and constraint satisfaction.

What it can answer

• Transitive reachability: "Can user input reach this SQL query?" — follows call chains across files and modules.
• Dead code detection: routines never called from any entry point.
• Cycle detection: circular call dependencies.
• Impact analysis: everything that depends on a modified method.

Token economics

A five-hop transitive analysis via grep might cost ~2,500 tokens across multiple tool calls, with the LLM reasoning about each hop. Chiasmus answers the same question in ~200 tokens with one tool call — the Prolog solver does the heavy computation locally.

Setup

claude mcp add chiasmus -- npx -y chiasmus

Exposes nine MCP tools for graph analysis, formal verification, template creation, and autonomous solving.

Limitations

Depends on tree-sitter grammar availability for the target language. The Prolog fact generation captures call-graph structure but not runtime behavior (reflection, dynamic dispatch, eval). Answers are sound for the static structure but not complete for languages with heavy metaprogramming.

https://github.com/yogthos/chiasmus