# How the GitNexus MCP Server Manages Multi-Repo Configurations and Parameter Routing

> Discover how the GitNexus MCP server expertly manages multi-repo configurations and parameter routing using global registry and in-memory backends for efficient tool call distribution.

- Repository: [Abhigyan Patwari/GitNexus](https://github.com/abhigyanpatwari/GitNexus)
- Tags: how-to-guide
- Published: 2026-03-08

---

**The GitNexus MCP server uses a global registry file and an in-memory LocalBackend to dynamically route tool calls to the correct repository based on a deterministic ID resolution algorithm.**

GitNexus is an open-source Model Context Protocol (MCP) server designed to index and query multiple local codebases simultaneously. Understanding how the GitNexus MCP server handles multi-repo configuration and parameter routing is essential for developers integrating AI agents like Cursor or Claude across several projects.

## The Three-Component Architecture for Multi-Repo Support

The system achieves multi-repository awareness through three tightly-coupled components that work together to discover, identify, and route requests to the correct codebase.

### Global Registry (`~/.gitnexus/registry.json`)

At the heart of the configuration lies a JSON registry located at `~/.gitnexus/registry.json`. This file lists every repository indexed by GitNexus, storing metadata including the repository name, absolute path, storage location, and KuzuDB database path. The registry is automatically updated when running `gitnexus analyze`, allowing the MCP server to discover new repositories without requiring a restart.

### LocalBackend ([`src/mcp/local/local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/src/mcp/local/local-backend.ts))

The `LocalBackend` class serves as the routing engine. Located in [`gitnexus/src/mcp/local/local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/mcp/local/local-backend.ts), this lightweight in-process backend reads the global registry during initialization and builds an in-memory map of `RepoHandle` objects. It manages lazy initialization of KuzuDB connections and contains the core resolution logic for determining which repository should handle each tool call.

### MCP Server ([`src/mcp/server.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/src/mcp/server.ts))

The actual JSON-RPC server implementation resides in [`gitnexus/src/mcp/server.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/mcp/server.ts). This component registers available MCP tools and forwards incoming requests to `LocalBackend.callTool()`. By delegating all repository-specific logic to the backend, the server maintains a clean separation between transport concerns and business logic.

## Repository Discovery and ID Resolution

When the MCP server starts, it initializes the backend which immediately begins the discovery process to map all available codebases.

### Loading the Global Registry

The `LocalBackend.init()` method (lines 90-99 in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts)) orchestrates the loading sequence:

1. **Registry Reading**: Calls `listRegisteredRepos()` from [`gitnexus/src/storage/repo-manager.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/storage/repo-manager.ts) to parse `~/.gitnexus/registry.json`
2. **Handle Creation**: For each entry, creates a `RepoHandle` containing the repository name, path, storage location, KuzuDB path, and basic statistics
3. **Cache Population**: Fills two Maps: `repos` (mapping `repoId` to `RepoHandle`) and `contextCache` (mapping `repoId` to lightweight `CodebaseContext`)
4. **Stale Entry Pruning**: Removes any repositories from memory that no longer exist in the registry

### Generating Stable Repository IDs

To handle collisions where multiple repositories share the same folder name (e.g., multiple `my-project` directories), GitNexus generates deterministic unique identifiers. The `repoId()` method in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts) (lines 155-166) implements the following logic:

```typescript
private repoId(name: string, repoPath: string): string {
  const base = name.toLowerCase();
  // Detect collision → hash the absolute path
  for (const [id, handle] of this.repos) {
    if (id === base && handle.repoPath !== path.resolve(repoPath)) {
      const hash = Buffer.from(repoPath).toString('base64url').slice(0, 6);
      return `${base}-${hash}`;
    }
  }
  return base;
}

```

This algorithm uses a base64url-encoded hash of the absolute path (first 6 characters) as a suffix when collisions are detected, ensuring that each repository receives a unique `repoId` used as the key for KuzuDB connection pooling.

## Parameter Routing in Tool Calls

Every MCP tool invocation undergoes a resolution process to determine which repository context to use, followed by dispatch to the appropriate handler.

### The Resolution Algorithm

The `resolveRepo()` and `resolveRepoFromCache()` methods in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts) implement a three-tier resolution strategy:

1. **Cache Lookup**: Checks the in-memory `repos` map for:
   - Exact `repoId` match
   - Case-insensitive repository name
   - Absolute path match
   - Substring match against available repositories

2. **Registry Refresh on Miss**: If the cache lookup fails, `refreshRepos()` is called once to reload the global registry and pick up newly-indexed repositories, then the lookup is retried.

3. **Error Handling**: The system provides specific error messages for different failure modes:
   - **No repositories indexed**: `No indexed repositories. Run: gitnexus analyze`
   - **Unknown repository specified**: `Repository "<value>" not found. Available: …`
   - **Ambiguous repository selection**: `Multiple repositories indexed. Specify which one with the "repo" parameter…`

### Tool Dispatch in `callTool`

The `LocalBackend.callTool()` method serves as the single entry point for all MCP tool executions (lines 89-122 in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts)). Its implementation uses a switch statement to route requests:

```typescript
async callTool(method: string, params: any): Promise<any> {
  if (method === 'list_repos') return this.listRepos();

  // Resolve repo (may throw if ambiguous)
  const repo = await this.resolveRepo(params?.repo);

  switch (method) {
    case 'query':          return this.query(repo, params);
    case 'cypher':         return this.formatCypherAsMarkdown(await this.cypher(repo, params));
    case 'context':        return this.context(repo, params);
    case 'impact':         return this.impact(repo, params);
    case 'detect_changes': return this.detectChanges(repo, params);
    case 'rename':         return this.rename(repo, params);
    // legacy aliases …
    default: throw new Error(`Unknown tool: ${method}`);
  }
}

```

**Key routing behaviors**:

- **`list_repos`**: Operates globally without requiring a repository parameter, returning the entire registry contents.
- **Repository-specific tools** (`query`, `cypher`, `context`, `impact`, `detect_changes`, `rename`): All require repository resolution via `resolveRepo()`. If the `repo` parameter is omitted and exactly one repository is indexed, that repository is used automatically.
- **Legacy aliases**: Tools like `search`, `explore`, and `overview` are mapped to their modern implementations while maintaining backward compatibility.

## Transport Layer Abstraction

The routing logic remains consistent across different transport mechanisms because both share the same `LocalBackend` instance.

### STDIO Transport

The command `gitnexus mcp` launches the STDIO-based server (implemented in [`gitnexus/src/cli/mcp.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/cli/mcp.ts)). This creates a `LocalBackend`, initializes it to load the global registry, and starts the JSON-RPC server over standard input/output streams.

### HTTP Transport

For web-based integrations, `mountMCPEndpoints` in [`gitnexus/src/server/mcp-http.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/server/mcp-http.ts) mounts the same MCP `Server` instance on an Express application under the `/api/mcp` endpoint. This allows AI agents to connect via HTTP while utilizing identical repository resolution and routing logic.

## Practical Code Examples

### Starting the MCP Server via STDIO

Launch the server to auto-discover all indexed repositories:

```bash
npx gitnexus mcp

```

Behind the scenes in [`gitnexus/src/cli/mcp.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/cli/mcp.ts):

```typescript
import { startMCPServer } from '../mcp/server.js';
import { LocalBackend } from '../mcp/local/local-backend.js';

const backend = new LocalBackend();
await backend.init();                 // loads the global registry
await startMCPServer(backend);        // STDIO JSON-RPC transport

```

### Listing All Registered Repositories

Send a JSON-RPC request to enumerate available repositories:

```json
{
  "jsonrpc": "2.0",
  "method": "call_tool",
  "params": { "name": "list_repos", "arguments": {} },
  "id": 1
}

```

Response excerpt:

```json
{
  "jsonrpc": "2.0",
  "result": {
    "content": [{ "type": "text", "text": "[{\"name\":\"my-app\",\"path\":\"/home/me/projects/my-app\",\"indexedAt\":\"2026-03-08…\"}, …]" }]
  },
  "id": 1
}

```

### Querying a Specific Repository

Force routing to a specific repository using the `repo` parameter:

```json
{
  "jsonrpc": "2.0",
  "method": "call_tool",
  "params": {
    "name": "query",
    "arguments": {
      "repo": "my-app",
      "query": "authentication",
      "limit": 5
    }
  },
  "id": 2
}

```

`LocalBackend.callTool` resolves `"my-app"` to its internal `repoId`, lazily initializes the KuzuDB connection via `ensureInitialized`, executes the hybrid search, and returns grouped results.

### Using the HTTP Endpoint

For integrations requiring HTTP transport:

```bash
curl -X POST http://localhost:3000/api/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","method":"call_tool","params":{"name":"context","arguments":{"repo":"my-app","name":"AuthService"}},"id":3}'

```

The `mountMCPEndpoints` function in [`gitnexus/src/server/mcp-http.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/gitnexus/src/server/mcp-http.ts) ensures the same routing logic applies regardless of transport protocol.

## Summary

- **Global Registry**: GitNexus maintains a central `~/.gitnexus/registry.json` file that tracks all indexed repositories, enabling automatic discovery without server restarts.
- **Stable ID Generation**: The `LocalBackend` generates deterministic repository IDs using base64url-encoded path hashes to handle naming collisions when multiple repositories share the same folder name.
- **Hierarchical Resolution**: Parameter routing follows a three-tier strategy—cache lookup, registry refresh, and specific error handling—to resolve repository references from IDs, names, paths, or substrings.
- **Unified Dispatch**: The `callTool` method in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts) serves as a single entry point that routes requests to repository-specific implementations or global tools like `list_repos`.
- **Transport Agnostic**: Both STDIO (`gitnexus mcp`) and HTTP (`/api/mcp`) transports share the same `LocalBackend` instance, ensuring consistent multi-repo behavior across integration methods.

## Frequently Asked Questions

### How does GitNexus handle two repositories with the same name?

When the `LocalBackend` detects a naming collision during initialization, it appends a base64url-encoded hash of the absolute path (first 6 characters) to the repository name. For example, two directories named `my-app` located at `/home/user/project-a/my-app` and `/home/user/project-b/my-app` would receive IDs like `my-app` and `my-app-a3f9b2`, ensuring unique identification in the internal `repos` Map.

### Can I query multiple repositories simultaneously in a single tool call?

No, the current architecture routes each tool call to exactly one repository context. The `resolveRepo()` method in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts) selects a single `RepoHandle` based on the `repo` parameter or defaults to the sole indexed repository when unambiguous. To query multiple repositories, clients must issue separate tool calls for each target repository and aggregate results externally.

### What happens if I specify a repository that hasn't been indexed yet?

If the `repo` parameter does not match any cached repository, the `LocalBackend` triggers `refreshRepos()` once to reload the global registry from `~/.gitnexus/registry.json`. If the repository still cannot be found after this refresh, the system returns a specific error message listing all available repositories: `Repository "<value>" not found. Available: [list]`. This ensures users immediately understand which repositories are accessible without restarting the server.

### How does the server distinguish between global and repository-specific tools?

The `callTool` method in [`local-backend.ts`](https://github.com/abhigyanpatwari/GitNexus/blob/main/local-backend.ts) checks the tool name before attempting repository resolution. Tools like `list_repos` execute immediately without requiring a `repo` parameter, returning the entire registry contents. For all other tools (`query`, `cypher`, `context`, `impact`, etc.), the method first calls `resolveRepo(params?.repo)` to obtain the target repository context before dispatching to the specific implementation. This branching logic ensures global operations remain available while maintaining strict repository scoping for code-specific queries.