Intro

Generate git commit messages on Magit using LLM providers, for example: OpenAI ChatGPT, Google Gemini, and more.

magit-gptcommit.intro.mp4

Dependencies

• magit
• llm
• curl

Setup

Note

If you are using gptel as a backend, please check out this branch(Not recommended!): gptel

magit-gptcommit depends on llm. Please read the documentation of llm for more details on how to set up providers. Debug logging for llm can be enabled by setting llm-log to t.

For example, to set up the OpenAI provider, first create an OpenAI API key. Once obtained, configure the llm OpenAI provider with the API key (replace "OPENAI-KEY" with your key):

(setq magit-gptcommit-llm-provider (make-llm-openai :key "OPENAI-KEY"))

Recommended: See below how to use Emacs auth-source to protect API keys for llm providers.

Activate magit-gptcommit-mode and open a Magit status buffer, the commit message will be automatically generated when changes are staged. You can run magit-gptcommit-generate when visiting a Magit status buffer to generate a commit message manually.

Setup example using use-package and straight:

(use-package magit-gptcommit
  :straight t
  :demand t
  :after magit
  :bind (:map git-commit-mode-map
              ("C-c C-g" . magit-gptcommit-commit-accept))
  :custom
  (magit-gptcommit-llm-provider (make-llm-openai :key "OPENAI-KEY"))

  :config
  ;; Enable magit-gptcommit-mode to watch staged changes and generate commit message automatically in magit status buffer
  ;; This mode is optional, you can also use `magit-gptcommit-generate' to generate commit message manually
  ;; `magit-gptcommit-generate' should only execute on magit status buffer currently
  ;; (magit-gptcommit-mode 1)

  ;; Add gptcommit transient commands to `magit-commit'
  ;; Eval (transient-remove-suffix 'magit-commit '(1 -1)) to remove gptcommit transient commands
  (magit-gptcommit-status-buffer-setup))

Usage

Command	Description
magit-gptcommit-generate	Generate gptcommit message and insert it into magit buffer.
magit-gptcommit-commit-create	Execute `magit-commit-create' and bring gptcommit message to editor.
magit-gptcommit-commit-quick	Accept gptcommit message and make a commit with current staged.
magit-gptcommit-commit-accept	Call on COMMIT_EDITMSG buffer, Accept gptcommit message after saving current message.
magit-gptcommit-abort	Abort the query process of current Repository.
magit-gptcommit-remove-section	Remove the gptcommit section from the current magit buffer.

Variable	Description
magit-gptcommit-prompt	Prompt.
magit-gptcommit-max-token	Default 4096, magit-gptcommit will truncate excessive characters based on 1 token = 4 chars
magit-gptcommit-determine-max-token	Whether to use the llm provider max tokens, used only if magit-gptcommit-max-token is nil.
magit-gptcommit-cache-limit	Cache size, default is 30
magit-gptcommit--cache	Cache of last generated commit message.
magit-gptcommit-llm-provider	llm provider or a function that returns an llm provider.
magit-gptcommit-llm-provider-temperature	llm provider temperature. (float)
magit-gptcommit-llm-provider-max-tokens	llm provider max generated tokens. (integer)

Using auth-source for API keys

Setup an llm provider for Google Gemini using use-package, straight, and Emacs auth-source, given that there is an auth-source secret stored with the host "generativelanguage.googleapis.com" and the user "apikey".

(use-package llm
  :straight t
  :init
  (require 'llm-gemini)
  :config
  (setopt llm-gemini-provider
          (make-llm-gemini :key (auth-info-password
                                 (car (auth-source-search
                                       :host "generativelanguage.googleapis.com"
                                       :user "apikey")))
                           :chat-model "gemini-1.5-flash-latest"))
  :custom
  (llm-warn-on-nonfree nil))

(use-package magit-gptcommit
  :straight t
  :demand t
  :after llm
  :custom
  (magit-gptcommit-llm-provider llm-gemini-provider)
...)

Content of the Auth Sources(~/.authinfo):

machine generativelanguage.googleapis.com login apikey password <api-key>

Tip

Mastering Emacs has a great article on how to store secrets in Emacs using GnuPG and Auth Sources: Keeping Secrets in Emacs

Todo

• Prompt optimization
  • There is still a lot of room for optimization. One problem is the context limitation, for example, GPT3.5 has a 4k context limit, so making a slightly larger edit will exceed the limit. Currently, the code roughly truncates the edit based on proportions to avoid this problem.
  • Alternatively, we could use a method similar to gptcommit. This method summarizes the diff of each file and then merges all the summaries to generate the commit message. However, this approach requires n + 2 requests to generate a single message.
• LRU Cache or Disk Cache
• NO Stream
• Other LLM Support

Credit

• llm Great project.
• gptcommit Very helpful, Prompt modified from this project.
• magit-todos This project has been of great help to me in learning magit development.
• GPT-Commit: Another Emacs pacakge for a similar purpose.