Code Graph RAG¶

AST-based code indexing and semantic search via Memgraph.

Overview¶

Property	Value
Component	`code-graph-rag`
Type	MCP Server
Port (Docker)	3850
Database	Memgraph (port 7687)
UI	Memgraph Lab (port 3100)

What It Does¶

AST Indexing - Parses code into Abstract Syntax Tree
Graph Storage - Stores entities and relationships in Memgraph
Semantic Search - Natural language queries about codebase
Call Graph - Function dependency analysis
Similar Code - Find similar code patterns

MCP Tools¶

Tool	Description
`index_repository`	Build code graph from repository
`query_code_graph`	Natural language code queries
`get_code_snippet`	Retrieve source code by qualified name
`surgical_replace_code`	Targeted code replacement
`read_file`	Read file contents
`write_file`	Write file contents
`list_directory`	List directory contents
`comprehensive_analysis`	LLM-powered entity analysis

Actions¶

Index Repository¶

index_repository {}

Parses and indexes the entire codebase into Memgraph.

Natural Language Query¶

query_code_graph {
  "natural_language_query": "What functions call UserService.create_user?"
}

Get Code Snippet¶

get_code_snippet {
  "qualified_name": "app.services.UserService.create_user"
}

Returns source code, file path, line numbers, and docstring.

Comprehensive Analysis¶

comprehensive_analysis {
  "qualified_name": "app.services.UserService",
  "scope": "full"
}

Scopes: full, structure, behavior, dependencies

Configuration¶

The host-side Claude/Copilot CLI talks to the containerized code-graph-rag server via a lightweight stdio proxy:

{
  "mcpServers": {
    "code-graph-rag": {
      "command": "node",
      "args": ["/path/to/code-graph-rag/dist/stdio-proxy.js"],
      "env": {
        "CODE_GRAPH_RAG_SSE_URL": "http://localhost:3850"
      }
    }
  }
}

Memgraph Database¶

Bolt Protocol: port 7687 Lab UI: http://localhost:3100

Direct Queries¶

# Connect via Memgraph Lab
open http://localhost:3100

# Or via cypher-shell
docker exec memgraph cypher-shell -u memgraph -p memgraph \
  "MATCH (n) RETURN count(n);"

Indexed Entities¶

Entity Type	Description
`Function`	Functions and methods
`Class`	Classes and types
`Module`	Files and packages
`Import`	Import relationships
`Call`	Function call relationships

Use Cases¶

Understanding Code¶

"What functions call registerWithPSM?"
"Show me all classes that implement the Repository interface"
"How does the authentication flow work?"

Finding Dependencies¶

"What modules import UserService?"
"Show the call graph for processPayment"

"Find the definition of handleError"
"What files contain database queries?"

Health Check¶

# MCP server
curl http://localhost:3850/health

# Memgraph
docker exec memgraph cypher-shell -u memgraph -p memgraph "RETURN 1;"

Integration with UKB¶

Code graph is automatically updated during ukb runs via the CodeGraphAgent in Semantic Analysis.

Troubleshooting¶

Memgraph not connecting¶

# Check container status
docker compose -f docker/docker-compose.yml ps memgraph

# View logs
docker compose -f docker/docker-compose.yml logs memgraph

# Restart Memgraph
docker compose -f docker/docker-compose.yml restart memgraph

Index not updating¶

# Force re-index
index_repository {}

# Check index status
query_code_graph { "natural_language_query": "How many functions are indexed?" }