@github/copilot-language-server

The Copilot Language Server enables any editor or IDE to integrate with GitHub Copilot via the language server protocol.

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Getting Started

To integrate with the Copilot Language Server, download the latest release from npm:

npm install @github/copilot-language-server

To run the language server, platform-specific binaries are available in the native directory of the npm package. For example, for macOS on arm64:

./node_modules/@github/copilot-language-server/native/darwin-arm64/copilot-language-server --version

Or you can use Node.js version 20.8 or later:

node ./node_modules/@github/copilot-language-server/dist/language-server.js --version

If using the language-server.js distribution, it is necessary to retain the entire dist directory contents.

Communication with the language server typically happens over stdio with --stdio. The language-server.js distribution additionally supports Node IPC with --node-ipc.

Communication Protocol

The Language Server Protocol (LSP) is used to communicate with the client. The base protocol is JSON-RPC 2.0 with additional headers.

The Copilot Language Server attempts to follow the LSP spec as closely as possible, but many custom messages are employed to support the unique features of Copilot.

Initialization

Per the LSP spec, the client is expected to send a initialize request to the language server as a first message. Example parameters:

{
    "processId": 1234,
    "workspaceFolders": [
        {
            "uri": "file:///home/user/project"
        }
    ],
    "capabilities": {
        "workspace": {"workspaceFolders": true}
    },
    "initializationOptions": {
        "editorInfo": {
            "name": "GNU ed",
            "version": "1.19"
        },
        "editorPluginInfo": {
            "name": "GitHub Copilot for ed",
            "version": "1.0.0"
        }
    }
}

After receiving the response to initialize, the second message the client must send is an initialized notification.

Configuration Management

After initialization, clients should send a workspace/didChangeConfiguration notification to inform the language server about the initial configuration, and again each time the configuration changes. Example parameters:

{
     "settings": {
        "http": {
            "proxy": "http://localhost:8888",
            "proxyStrictSSL": true,
            "proxyKerberosServicePrincipal": "spn"
        },
        "telemetry": {
            "telemetryLevel": "all"
        },
        "github-enterprise": {
            "uri": "https://example.ghe.com"
        }
    }
}

Pull based configuration on workspace/configuration is also supported.

Workspace Folders Synchronization

Workspace folders are optional but highly recommended as they greatly improve the quality of suggestions. See the LSP spec for workspace/didChangeWorkspaceFolders.

Text Document Synchronization

Per the LSP spec for text document synchronization, support for textDocument/didOpen, textDocument/didChange, and textDocument/didClose is required, using incremental sync.

Text Document Focusing

Additionally a custom textDocument/didFocus notification should be sent when the client focuses another document (e.g., changing tabs). Example parameters:

{
    "textDocument": {
        "uri": "file:///path/to/file"
    }
}

If no document is focused, a request with no parameters ({}) may be sent.

Status Notification

The status is sent to the client as a didChangeStatus notification. Typically this would be conveyed to the user in a status bar icon or other UI affordance.

Notification includes the following fields:

• message - a string describing the status (can be empty)
• kind - status of the language server:
  • 'Normal' - When everything is working normally.
  • 'Error' - When not authorized and authenticated.
  • 'Warning' - When there is a temporary issue, such as a failed HTTP request.
  • 'Inactive' - When the current file is ignored due to file size or content exclusions.

Authentication

To sign in, call signIn. This will return a response like the following:

{
    "userCode": "ABCD-EFGH",
    "command": {
        "command": "github.copilot.finishDeviceFlow",
        "arguments": [],
        "title": "Sign in"
    }
}

Instruct the user to copy the userCode to their clipboard (and/or copy it programmatically). When the user is ready, invoke workspace/executeCommand to execute the command. This will open a browser window that walks the user through the authentication process. Shortly (up to 10 seconds) after the user finishes signing in, you should see a status notification reflecting the new state.

If available, the language server will use window/showDocument to open the URL. Otherwise, it will attempt to open the URL natively (e.g., with /usr/bin/open on macOS).

To sign out, call signOut.

Inline Completions

The textDocument/inlineCompletion request from the draft version of the next LSP spec is used to retrieve inline ("ghost text") completions, with some non-standard additions (textDocument.version and formattingOptions) to the parameters:

{
    "textDocument": {
        "uri": "file:///path/to/file",
        "version": 0
    },
    "position": {"line": 1, "character": 2},
    "context": {
        "triggerKind": 2
    },
    "formattingOptions": {
        "tabSize": 4,
        "insertSpaces": true
    }
}

The result is an object containing an items array.

{
    "items": [
        {
            "insertText": "a helpful suggestion",
            "range": {
                "start": {"line": 1, "character": 0},
                "end": {"line": 1, "character": 2}
            },
            "command": {
                "command": "github.copilot.didAcceptCompletionItem",
                "arguments": ["some id"]
            }
        }
    ]
}

Newlines in insertText should be normalized as is appropriate for the editor before inserting into the document.

The command field, per the LSP spec, is called via workspace/executeCommand after the user accepts the completion. Copilot uses this for acceptance telemetry.

The LSP spec does not provide an event for showing the completion, so a custom textDocument/didShowCompletion is used. Call it with an item parameter containing the full completion item:

{
    "item": {
        "insertText": "a helpful suggestion",
        "range": {
            "start": {"line": 1, "character": 0},
            "end": {"line": 1, "character": 2}
        },
        "command": {
            "command": "github.copilot.didAcceptCompletionItem",
            "arguments": ["some id"]
        }
    }
}

Similarly, for partial acceptance, send a textDocument/didPartiallyAcceptCompletion notification with the full item, plus the length (in UTF-16 codepoints) of the completion that was accepted:

{
    "item": {
        "insertText": "a helpful suggestion",
        "range": {
            "start": {"line": 1, "character": 0},
            "end": {"line": 1, "character": 2}
        },
        "command": {
            "command": "github.copilot.didAcceptCompletionItem",
            "arguments": ["some id"]
        }
    },
    "acceptedLength": 9
}

Note that the acceptedLength includes everything from the start of insertText to the end of the accepted text. It is not the length of the accepted text itself.

Panel Completions

Panel completions are used for "Open Copilot" style completions. They are similar to inline completions, but are shown in a separate panel. They are retrieved using the custom textDocument/copilotPanelCompletion request, which has parameters closely modeled after textDocument/inlineCompletion:

{
    "textDocument": {
        "uri": "file:///path/to/file",
        "version": 0
    },
    "position": {"line": 1, "character": 2},
    "partialResultToken": "some token"
}

If provided, the partialResultToken is used to stream partial results back to the client. Both the return type and the partial result type are the same as for inline completions: an object containing an items array. These items have the same command that must be invoked with workspace/executeCommand after accepting to trigger acceptance telemetry. Partial acceptance and shown events are not supported here.

Cancellation

textDocument/inlineCompletion supports cancel-previous strategy for cancellation: If you send new completions request, the previous request is cancelled.

Additionally the LSP $/cancelRequest method is supported to cancel any request. It is strongly encouraged to eagerly cancel completion requests as soon as possible.

Logs

Logs are sent to the client as window/logMessage notifications.

Messages

The client may be sent window/showMessageRequest requests. Support for these messages is essential as they are used for important notifications including account and billing.