copilot.el

Both Chat and NES are independent modules that layer on top of the core infrastructure.

Chat (copilot-chat.el)

Manages conversations using conversation/create, conversation/turn, and conversation/destroy methods. Responses stream in via $/progress notifications. It also registers a conversation/context request handler so the server can retrieve editor context (file, cursor, source text). The UI is contained in a *copilot-chat* buffer.

Next Edit Suggestions (copilot-nes.el)

Predicts edits based on recent history using textDocument/copilotInlineEdit. It displays suggestions as two overlays: one for deleted text (strikethrough) and one for inserted text. Unlike inline completions, NES can modify or delete text anywhere in the file. Acceptance is a two-step process: the first TAB press jumps to the edit location, and the second applies it.

copilot.el uses track-changes (Emacs 30+) to send incremental textDocument/didChange notifications.

Key technical requirements:

• Offsets: All positions must use UTF-16 code-unit offsets as required by the LSP specification. The function copilot--utf16-offset is used to handle characters outside the Basic Multilingual Plane.
• Lifecycle Notifications:
  • textDocument/didOpen: Sent when a buffer with copilot-mode active first gains focus.
  • textDocument/didFocus: Sent on subsequent focus changes.
  • textDocument/didClose: Sent when the buffer is killed or copilot-mode is disabled.
• Truncation: For large buffers, text is truncated based on copilot-max-char (default 100,000 characters) using a windowing strategy centered around the point.

To get started with copilot.el, add the following configuration to your Emacs setup to enable it in programming modes and bind common completion keys. After configuring, you must run two commands to finalize the setup:

1. M-x copilot-install-server to download the language server.
2. M-x copilot-login to authenticate with GitHub.

(use-package copilot
  :ensure t
  :hook (prog-mode . copilot-mode)
  :bind (:map copilot-completion-map
              ("<tab>" . copilot-accept-completion)
              ("TAB" . copilot-accept-completion)
              ("C-<tab>" . copilot-accept-completion-by-word)
              ("C-TAB" . copilot-accept-completion-by-word)
              ("C-n" . copilot-next-completion)
              ("C-p" . copilot-previous-completion)))

To use copilot.el in Doom Emacs, follow these two steps:

1. Add the package definition to ~/.doom.d/packages.el:

(package! copilot
  :recipe (:host github :repo "copilot-emacs/copilot.el" :files ("*.el")))

2. Configure it in ~/.doom.d/config.el:

;; accept completion from copilot and fallback to company
(use-package! copilot
  :hook (prog-mode . copilot-mode)
  :bind (:map copilot-completion-map
              ("<tab>" . 'copilot-accept-completion)
              ("TAB" . 'copilot-accept-completion)
              ("C-TAB" . 'copilot-accept-completion-by-word)
              ("C-<tab>" . 'copilot-accept-completion-by-word)))

Note: It is strongly recommended to enable the childframe option in your company module ((company +childframe)) to prevent overlay conflicts.

Network Proxy

Set copilot-network-proxy using the following format: '(:host "HOST" :port PORT :username "USER" :password "PASS").

(setq copilot-network-proxy '(:host "127.0.0.1" :port 7890))

Handling TLS-inspecting Proxies (e.g., Zscaler)

If your proxy intercepts TLS and uses self-signed certificates, you have two options:

1. Tell the language server to reject unauthorized certificates:

   (setq copilot-network-proxy '(:host "127.0.0.1" :port 7890 :rejectUnauthorized :json-false))

2. Make the server trust your CA by exporting NODE_EXTRA_CA_CERTS before starting Emacs:

   export NODE_EXTRA_CA_CERTS=/path/to/ca-chain.pem
   emacs

   Alternatively, set it via (setenv "NODE_EXTRA_CA_CERTS" "...") in your config, provided it is done before the language server process starts.

You can enable Copilot completions automatically for programming buffers using copilot-mode. Alternatively, you can enable it globally using global-copilot-mode.

To customize when completions trigger or are displayed, use the following predicate functions:

• copilot-enable-predicates / copilot-disable-predicates (triggering)
• copilot-enable-display-predicates / copilot-disable-display-predicates (displaying)

For manual control, you can call copilot-complete directly and use copilot-clear-overlay in a post-command-hook to dismiss them.

For Emacs 30 and newer, you can install directly from the GitHub repository using the :vc keyword in use-package.

(use-package copilot
  :vc (:url "https://github.com/copilot-emacs/copilot.el"
            :rev :newest
            :branch "main"))

M-x copilot-menu opens a transient menu (built on the transient package) that provides one-keystroke access to common commands. It serves as a status overview, showing the current state of copilot-mode, agent mode, and the selected chat model. It includes sections for completions, chat, agent mode, account/usage info, and server management.

Note: On Emacs 27.2, transient may not be available, but copilot.el will still function normally.

If you don't want to use the menu, you can always use M-x copilot- followed by TAB to search for commands.

The simplest way to install copilot.el is via MELPA using use-package or the built-in package-install command.

(use-package copilot
  :ensure t)