Generating a git commit message is quickly become a classic GenAI application for developers.

To help with this, we will craft a GenAIScript script.

The script acts as a regular node.js automation script and uses runPrompt
to issue calls to the LLM and ask the user to confirm the generated text.

? Explaining the Script

The script begins by importing necessary functions from @inquirer/prompts:

import { select, input, confirm } from "@inquirer/prompts"

These functions will be used to interact with the user, asking them to confirm actions or input data.

Next, we check if there are any staged changes in the Git repository:

let { stdout } = await host.exec("git", ["diff", "--cached"])

If no changes are staged, we ask the user if they want to stage all changes. If the user confirms, we stage all changes. Otherwise, we bail out.

    const stage = await confirm({
        message: "No staged changes. Stage all changes?",
        default: true,
    })
    if (stage) {
        await host.exec("git", ["add", "."])
        stdout = (await host.exec("git", ["diff", "--cached"])).stdout
    }
    if (!stdout) cancel("no staged changes")

We generate an initial commit message using the staged changes:

message = (
    await runPrompt(
        (_) => {
            _.def("GIT_DIFF", stdout, { maxTokens: 20000 })
            _.$`GIT_DIFF is a diff of all staged changes, coming from the command:
\`\`\`
git diff --cached
\`\`\`
Please generate a concise, one-line commit message for these changes.
- do NOT add quotes`
        },
        { cache: false, temperature: 0.8 }
    )
).text

The prompt configuration above indicates that the message should be concise,
related to the "git diff --cached" output, and should not include quotes.

User chooses how to proceed with the generated message:

    choice = await select({
        message,
        choices: [
            { name: "commit", value: "commit", description: "accept message and commit" },
            ...
        ],
    })

Options are given to edit or regenerate the message. If the user chooses to edit the message, we ask them to input a new message:

    if (choice === "edit") {
        message = await input({
            message: "Edit commit message",
            required: true,
        })
        choice = "commit"
    }

If the user chooses to commit the message, we commit the changes:

    if (choice === "commit" && message) {
        console.log((await host.exec("git", ["commit", "-m", message])).stdout)
    }

? Running the Script

You can run this script using the CLI.

genaiscript run gcm

Since it uses the @inquirer/prompts package, you will need to install this package first:

npm install --save-dev @inquirer/prompts

If you are using npx,

npx -p @inquirer/prompts genaiscript -p genaiscript  -- genaiscript run gcm

This command will run the script, and guide you through the process of generating and committing a Git message using AI, making your commits more informative and consistent.

You can wrap this command in a gcm.sh file or in your package script section in package.json:

{
    "devDependencies": {
        "@inquirer/prompts": "...",
        "genaiscript": "..."
    },
    "scripts": {
        "gcm": "genaiscript run gcm"
    }
}

Then you can run the script using:

npm run gcm

Acknowledgements

This script was inspired from Karpathy's commit message generator.