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https://github.com/opticlm/connector

A TypeScript SDK bridges IDE's LSP capabilities with MCP, designed for who building AI coding agents.
https://github.com/opticlm/connector

lsp mcp mcp-server modelcontextprotocol npm typescript

Last synced: 4 months ago
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A TypeScript SDK bridges IDE's LSP capabilities with MCP, designed for who building AI coding agents.

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README 

          
# @opticlm/connector



Provides an abstract interface that allows LLMs to connect to fact sources such as LSPs, code diagnostics, symbol definitions/references, links, and frontmatter; currently includes an MCP implementation.



## Table of Contents



- [Installation](#installation)

- [Quick Start](#quick-start)

- [MCP Tools](#mcp-tools)

- [Tool Callbacks](#tool-callbacks)

- [MCP Resources](#mcp-resources)

- [Auto-Complete for File Paths](#auto-complete-for-file-paths)

- [Subscription and Change Notifications](#subscription-and-change-notifications)

- [Symbol Resolution](#symbol-resolution)

- [Pipe IPC (Out-of-Process)](#pipe-ipc-out-of-process)

- [LSP Client (Built-in)](#lsp-client-built-in)

- [Requirements](#requirements)

- [License](#license)



## Installation



```bash

npm install @opticlm/connector

# or

pnpm add @opticlm/connector

```



## Quick Start



Providers are installed onto an MCP server using `install()` from `@opticlm/connector/mcp`. Each call registers the tools and resources for that specific provider. Providers that depend on file access (definition, references, hierarchy, edit) receive a `fileAccess` option.



You can pass a single provider or an array of providers of the same type. When an array is given, their results are merged automatically — array-returning methods (e.g. `provideDefinition`) are concatenated, void methods are called on all providers in parallel, and callback registrars (e.g. `onDiagnosticsChanged`) are registered on every provider in the array.



```typescript

import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'

import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'

import { install } from '@opticlm/connector/mcp'

import * as fs from 'fs/promises'



// 1. Create your MCP server

const server = new McpServer({

  name: 'my-ide-mcp-server',

  version: '1.0.0'

})



// 2. Implement File Access

const fileAccess = {

  readFile: async (uri: string) => {

    return await fs.readFile(uri, 'utf-8')

  },

  readDirectory: (uri: string) => yourIDE.workspace.readDirectory(uri),

}



// 3. Implement Edit Provider

const edit = {

  // Show diff in your IDE and get user approval

  previewAndApplyEdits: async (operation) => {

    return await showDiffDialog(operation)

  },

}



// 4. Implement LSP Capability Providers

const definition = {

  provideDefinition: async (uri, position) => {

    return await lspClient.getDefinition(uri, position)

  },

}



const diagnostics = {

  provideDiagnostics: async (uri) => {

    return await lspClient.getDiagnostics(uri)

  },

  getWorkspaceDiagnostics: async () => {

    return await lspClient.getWorkspaceDiagnostics()

  },

  onDiagnosticsChanged: (callback) => {

    yourIDE.onDiagnosticsChanged((uri) => callback(uri))

  },

}



const outline = {

  provideDocumentSymbols: async (uri) => {

    return await lspClient.getDocumentSymbols(uri)

  },

}



// 5. Install providers onto the server

//    fileAccess is installed first; others receive it as an option when needed

install(server, fileAccess)

install(server, edit, { fileAccess })

install(server, definition, { fileAccess })

install(server, diagnostics, { fileAccess })

install(server, outline, { fileAccess })



// You can also pass an array to merge multiple providers of the same type:

// install(server, [definition, anotherDefinition], { fileAccess })

// install(server, [diagnostics, anotherDiagnostics], { fileAccess })



// 6. Connect to transport (you control the server lifecycle)

const transport = new StdioServerTransport()

await server.connect(transport)

```



Each `install()` call is independent — only install the providers your IDE actually supports. The `fileAccess` option is required for providers that read files (edit, definition, references, hierarchy) and is used optionally by others for path auto-complete.



## MCP Tools



The SDK automatically registers tools based on which providers you install:



### `goto_definition`



Navigate to the definition of a symbol.



### `find_references`



Find all references to a symbol.



### `find_file_references`



Find all references to a file across the workspace (e.g., all files that import or link to the given file).



Only registered when your `ReferencesProvider` implements the optional `provideFileReferences` method.



### `call_hierarchy`



Get call hierarchy for a function or method.



### `apply_edit`



Apply a text edit to a file using hashline references (requires user approval).



The `files://` resource returns file content in **hashline format** — each line is prefixed with `:|`, where the hash is a 2-char CRC16 digest of the line's content. To edit a file, reference lines by these hashes. If the file has changed since the last read, the hashes won't match and the edit is rejected, preventing stale overwrites.



### `global_find`



Search for text across the entire workspace.



### `get_link_structure`



Get all links in the workspace, showing relationships between documents.



### `add_link`



Add a link to a document by finding a text pattern and replacing it with a link.



### `get_frontmatter_structure`



Get frontmatter property values across documents.



### `set_frontmatter`



Set a frontmatter property on a document.



## Tool Callbacks



Each provider with tools accepts optional `onInput` and `onOutput` callbacks in its install options. These fire synchronously around each tool invocation — `onInput` before processing, `onOutput` after a successful result (not on errors).



Use them for logging, telemetry, or testing:



```typescript

import { install } from '@opticlm/connector/mcp'



// EditProvider — apply_edit

install(server, editProvider, {

  fileAccess,

  onEditInput: (input) => {

    console.log('edit requested:', input.uri, input.description)

  },

  onEditOutput: (output) => {

    console.log('edit result:', output.success, output.message)

  },

})



// DefinitionProvider — goto_definition + goto_type_definition

install(server, definitionProvider, {

  fileAccess,

  onDefinitionInput: (input) => log('goto_definition', input),

  onDefinitionOutput: (output) => log('goto_definition result', output.snippets.length),

  onTypeDefinitionInput: (input) => log('goto_type_definition', input),

  onTypeDefinitionOutput: (output) => log('goto_type_definition result', output.snippets.length),

})

```



## MCP Resources



The SDK automatically registers resources based on which providers you install:



### `diagnostics://{path}`



Get diagnostics (errors, warnings) for a specific file.



**Resource URI Pattern:** `diagnostics://{+path}`



**Example:** `diagnostics://src/main.ts`



Returns diagnostics formatted as markdown with location, severity, and message information.



**Subscription Support:** If your `DiagnosticsProvider` implements `onDiagnosticsChanged`, these resources become subscribable. When diagnostics change, the driver sends resource update notifications.



### `diagnostics://workspace`



Get diagnostics across the entire workspace.



**Resource URI:** `diagnostics://workspace`



Only available if your `DiagnosticsProvider` implements the optional `getWorkspaceDiagnostics()` method.



Returns workspace diagnostics grouped by file, formatted as markdown.



**Subscription Support:** If your `DiagnosticsProvider` implements `onDiagnosticsChanged`, this resource becomes subscribable.



### `outline://{path}`



Get the document outline (symbol tree) for a file.



**Resource URI Pattern:** `outline://{+path}`



**Example:** `outline://src/components/Button.tsx`



Returns document symbols formatted as a hierarchical markdown outline, including:

- Symbol names and kinds (class, function, method, etc.)

- Source locations

- Nested children (e.g., methods within classes)



No subscription support for this resource (read-only).



### `files://{path}`



For directories: returns directory children (git-ignored files excluded, similar to `ls`). For files: returns content in **hashline format** with optional line range and regex filtering.



**Hashline format:** Each line is prefixed with `:|`, where `` is the 1-based line number and `` is a 2-char CRC16 hex digest of the line content. For example:



```

1:a3|function hello() {

2:f1|  return "world"

3:0e|}

```



These hashes serve as content-addressed anchors for the `apply_edit` tool — if the file changes between read and edit, the hash mismatch is detected and the edit is safely rejected.



**Resource URI Pattern:** `files://{+path}`



**Example:** `files://src`, `files://src/index.ts`, `files://src/index.ts#L1-L2`, `files://src/index.ts?pattern=^import`, `files://src/index.ts?pattern=TODO#L10-L50`



No subscription support for this resource (read-only).



### `outlinks://{path}`



Get outgoing links from a specific file.



**Resource URI Pattern:** `outlinks://{+path}`



**Example:** `outlinks://notes/index.md`



Returns a JSON array of links originating from the specified document.



No subscription support for this resource (read-only).



### `backlinks://{path}`



Get incoming links (backlinks) to a specific file.



**Resource URI Pattern:** `backlinks://{+path}`



**Example:** `backlinks://notes/topic-a.md`



Returns a JSON array of links pointing to the specified document.



No subscription support for this resource (read-only).



### `frontmatter://{path}`



Get frontmatter metadata for a specific file.



**Resource URI Pattern:** `frontmatter://{+path}`



**Example:** `frontmatter://notes/index.md`



Returns a JSON object containing all frontmatter properties and values for the document.



No subscription support for this resource (read-only).



## Auto-Complete for File Paths



All resource templates with a `{+path}` variable (`files://`, `diagnostics://`, `outline://`, `outlinks://`, `backlinks://`, `frontmatter://`) support MCP auto-completion. When an MCP client calls `completion/complete` with a partial file path, the SDK uses `readDirectory` from your `FileAccessProvider` to suggest matching entries.



- Completion is case-insensitive and splits input into a directory and prefix (e.g., `src/ser` reads `src/` and filters by `ser`)

- If `readDirectory` fails (e.g., the directory doesn't exist), an empty list is returned

- Results are capped at 100 items by the MCP SDK



This works automatically — no additional configuration is needed.



## Subscription and Change Notifications



Providers can implement optional `onDiagnosticsChanged` and `onFileChanged` callbacks to make resources subscribable:



```typescript

import { install } from '@opticlm/connector/mcp'



install(server, {

  readFile: async (uri) => { /* ... */ },

  readDirectory: async (path) => { /* ... */ },

  onFileChanged: (callback) => {

    yourIDE.onFileChanged((uri) => callback(uri))

  },

})



install(server, {

  provideDiagnostics: async (uri) => { /* ... */ },

  getWorkspaceDiagnostics: async () => { /* ... */ },

  onDiagnosticsChanged: (callback) => {

    yourIDE.onDiagnosticsChanged((uri) => callback(uri))

  },

})

```



When diagnostics or files change, call the registered callback with the affected file URI. The driver will send MCP resource update notifications to subscribers.



## Symbol Resolution



The SDK uses a robust algorithm to handle imprecise LLM positioning:



1. Target the `lineHint` (converting 1-based to 0-based)

2. Search for `symbolName` in that line

3. **Robustness Fallback**: If not found, scan +/- 2 lines (configurable)

4. Use `orderHint` to select the Nth occurrence if needed



Configure the search radius via the `resolverConfig` option:



```typescript

install(server, definitionProvider, {

  fileAccess,

  resolverConfig: {

    lineSearchRadius: 5,  // Default: 2

  },

})

```



## Pipe IPC (Out-of-Process)



When the MCP server runs in a separate process from the IDE plugin (e.g., spawned via stdio transport), the Pipe IPC layer lets the two communicate over a named pipe.



**IDE plugin side** — expose providers:



```typescript

import { servePipe } from '@opticlm/connector/pipe'



const server = await servePipe({

  pipeName: 'my-ide-lsp',

  fileAccess: { /* ... */ },

  definition: { /* ... */ },

  // ...

  // Add only the providers your IDE supports

})

// server.pipePath        — the resolved pipe path

// server.connectionCount — number of connected clients

// await server.close()   — shut down

```



**MCP server side** — connect and install proxy providers:



```typescript

import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'

import { connectPipe } from '@opticlm/connector/pipe'

import { install } from '@opticlm/connector/mcp'



const conn = await connectPipe({

  pipeName: 'my-ide-lsp',

  connectTimeout: 5000,  // optional, default 5000ms

})



// conn exposes proxy providers as named fields:

// conn.fileAccess, conn.definition, conn.diagnostics, etc.

// conn.availableMethods lists all methods the server exposes



const mcpServer = new McpServer({ name: 'my-mcp', version: '1.0.0' })



if (conn.fileAccess) install(mcpServer, conn.fileAccess)

if (conn.definition && conn.fileAccess)

  install(mcpServer, conn.definition, { fileAccess: conn.fileAccess })

// ...

// Install whichever proxy providers are available



// When done:

conn.disconnect()

```



The handshake automatically discovers which providers the server exposes and builds typed proxies. Change notifications are forwarded as push notifications to all connected clients. Multiple clients can connect to the same pipe simultaneously.



## LSP Client (Built-in)



For standalone MCP servers that need to communicate directly with an LSP server (e.g., when not running inside an IDE plugin), `LspClient` spawns a language server process and automatically creates capability providers based on the server's reported capabilities.



```typescript

import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'

import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'

import { createLspClient } from '@opticlm/connector'

import { install } from '@opticlm/connector/mcp'

import * as fs from 'fs/promises'



// 1. Create and start the LSP client

const lsp = createLspClient({

  command: 'typescript-language-server',

  args: ['--stdio'],

  workspacePath: '/path/to/project',

  readFile: (path) => fs.readFile(path, 'utf-8'),

})



await lsp.start()



// 2. Wire providers into MCP

const server = new McpServer({ name: 'my-mcp', version: '1.0.0' })



const fileAccess = {

  readFile: (uri: string) => fs.readFile(uri, 'utf-8'),

  readDirectory: async () => [],

}



// Providers are automatically created based on server capabilities

install(server, fileAccess)

if (lsp.definition) install(server, lsp.definition, { fileAccess })



const transport = new StdioServerTransport()

await server.connect(transport)

```



### `LspClientOptions`



```typescript

interface LspClientOptions {

  command: string               // LSP server command to spawn

  args?: string[]               // Command arguments (e.g., ['--stdio'])

  workspacePath: string         // Absolute path to the workspace root

  readFile: (path: string) => Promise  // File reader for document sync

  env?: Record  // Additional environment variables

  initializationOptions?: unknown  // LSP initializationOptions

  documentIdleTimeout?: number  // Auto-close open docs after ms (default: 30000)

  requestTimeout?: number       // Timeout for LSP requests in ms (default: 30000)

}

```



### How It Works



1. `start()` spawns the LSP server process and performs the initialize/initialized handshake

2. The server's `ServerCapabilities` response determines which providers are created

3. Providers that the server does not support remain `undefined`

4. Documents are automatically opened/closed with the server on demand, with an idle timeout for cleanup



### Lifecycle



```typescript

const lsp = createLspClient({ /* ... */ })



lsp.getState()  // 'idle'

await lsp.start()

lsp.getState()  // 'running'



// Use lsp.definition, lsp.references, etc.



await lsp.stop()

lsp.getState()  // 'dead'

```



## Requirements



- Node.js >= 18.0.0

- TypeScript >= 5.7.0



## License



MIT