PRNote

PRNote is a JavaScript GitHub Action that turns branch names, commit messages, changed files, and selected diff excerpts into a concise pull request title and description.

It is intentionally narrow: PRNote documents a change; it does not review code, scan security, score pull requests, or replace CI.

Usage

Create .github/workflows/prnote.yml in the repository that will use PRNote:

name: PRNote

on:
  pull_request:
    types: [opened]

permissions:
  contents: read
  pull-requests: write

jobs:
  generate-pr-note:
    runs-on: ubuntu-latest
    steps:
      - name: Generate PR title and description
        uses: richardj46/prnote-action@v0.1.1
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          gemini-api-key: ${{ secrets.GEMINI_API_KEY }}

Add GEMINI_API_KEY as a repository or organization Actions secret to enable AI generation. The key is optional: without it—or whenever Gemini fails—PRNote generates a deterministic title and description from commit history and changed-file metadata. No checkout step is required: PRNote reads PR metadata and patches through the GitHub API and never executes pull request code.

Safe defaults

By default, PRNote writes its canonical pull-request title and commit-message description to the PR, replacing existing title/body content. This guarantees that GitHub's editable merge form can use the PRNote values. Set overwrite-title: "false" or overwrite-body: "false" to restore preservation of meaningful human-written content.

PRNote does not write a pull request conversation comment by default. It updates only the PR title and body. A managed summary comment can be enabled explicitly with comment: "true". When commenting is disabled and neither field is eligible for an update, PRNote stops before collecting repository context or calling Gemini.

Generation and GitHub API failures are non-blocking. The action emits a warning and reports the affected output as false.

Inputs

Input	Default	Description
github-token	required	Token used to read and update the PR.
gemini-api-key	optional	Gemini API key. When absent or unavailable, commit-history generation is used.
update-title	true	Allow title generation.
update-body	true	Allow body generation.
comment	false	Optionally create or update one managed PR conversation comment.
overwrite-title	true	Replace the existing title with the canonical pull-request title.
overwrite-body	true	Replace the existing body with the commit-message merge description.
max-diff-characters	20000	Maximum selected patch characters sent for generation; use 0 to send no patches.
timeout-seconds	120	Maximum duration of each Gemini attempt; transient failures are retried once.
exclude	generated/noisy files	Comma-separated minimatch globs excluded from file and diff context. Providing this input replaces the defaults.
language	en	Output language or locale instruction.
model	gemini-3.5-flash	Gemini Interactions API model.

Default exclusions include lockfiles, source maps, minified JavaScript, build output, coverage, generated directories, .next, and Rust target output.

The action exposes title-updated, body-updated, and comment-written outputs.

The managed comment is identified by an invisible marker, so rerunning PRNote updates the existing bot comment instead of adding duplicates. PRNote uses GitHub's pull request issue-comment endpoint and does not create commit comments.

In the managed PR comment, the Changes section is a bullet list of the source branch's commit messages in GitHub commit order. The separate Commit Messages section remains part of the PR description used for merge-message defaults, but is omitted from the comment to avoid duplication.

Merge commit title and description

PRNote writes the generated title and description to the pull request. GitHub can then copy them into the editable merge dialog when a user merges the PR after checks pass.

To guarantee that the PR fields contain PRNote's generated values rather than preserved human-written content, configure the action with explicit overwrite mode:

- uses: your-github-name/prnote@v1
  with:
    github-token: ${{ secrets.GITHUB_TOKEN }}
    gemini-api-key: ${{ secrets.GEMINI_API_KEY }}
    update-title: "true"
    update-body: "true"
    overwrite-title: "true"
    overwrite-body: "true"

Configure this once in the target repository:

1. Open Settings → General → Pull Requests.
2. Enable Allow merge commits.
3. In its default-message dropdown, select Pull request title and description. This corresponds to merge commit title = PR title and merge commit message = PR body.

After checks pass, refresh or reopen the merge form. GitHub should pre-fill the merge commit title from the PR title and the extended description from the PR body. If the extended description contains <source branch>: pull request, the repository is configured to use PR title as the merge message; change it to Pull request title and description. The user can review or edit both fields before clicking Merge. PRNote does not merge automatically and needs only contents: read plus pull-requests: write permissions.

The generated description ends with a Commit Messages section built directly from the source branch. PRNote preserves GitHub's commit order, normalizes each commit subject and body onto one line, and places each commit message on its own list line. This section therefore carries into the editable merge-commit description when the repository uses the pull request title and description as its default message.

GitHub does not expose a per-pull-request API for independently setting the editable merge-dialog defaults. The supported path is: PRNote updates the PR title/body, then the repository's default commit-message setting copies those fields into the merge form.

Gemini uses low thinking for this focused summarization task and does not store Interactions API objects (store: false). If a large pull request still times out, reduce max-diff-characters or increase timeout-seconds.

Commit-history fallback

If Gemini times out, returns no model text, rejects the request, or no API key is configured, PRNote still updates eligible fields. The fallback title uses the first meaningful non-merge commit subject. The description lists unique commit subjects, exact file/change totals, testing evidence without claiming tests passed, and a truncation note when applicable.

Overwrite example

with:
  github-token: ${{ secrets.GITHUB_TOKEN }}
  gemini-api-key: ${{ secrets.GEMINI_API_KEY }}
  overwrite-title: "true"
  overwrite-body: "true"
  language: en-GB
  max-diff-characters: "10000"

Overwrite mode is explicit because it can replace carefully written content.

Generated format

PRNote uses one deterministic pull-request title convention:

<source branch>: pull request

The PR body used as GitHub's editable merge extended description contains only the source-branch commit messages in commit order:

 - first commit message
 - second commit message

Titles are limited to 120 characters. Canonical title/body overwrite is enabled by default; it can be disabled explicitly.

PRNote asks the model for schema-validated structured output and renders only populated sections:

## Summary

Adds a passwordless sign-in flow using emailed verification links.

## Changes

- Add endpoints for requesting and verifying sign-in links
- Add pending and completed verification states

## Testing

- Add unit tests for verification token validation

## Notes

- Requires the EMAIL_FROM environment variable

The prompt forbids invented tests, issue numbers, deployment steps, and configuration requirements. A generated note is validated before any update is sent to GitHub.

Privacy and fork pull requests

PRNote sends the current PR title/body, branch names, commit messages, changed filenames and statistics, plus up to max-diff-characters selected patch characters to the Gemini API. Excluded files are omitted from both the file list and patch excerpts. GitHub and Google apply their respective data-handling terms; evaluate those terms for your repository before enabling the action.

Normal pull_request workflows do not receive repository secrets for pull requests from untrusted forks, so PRNote cannot call Gemini in that situation. This is a documented MVP limitation. Avoid changing the workflow to check out untrusted code under pull_request_target, because doing so can expose secrets.

Development

Requires Node.js 20 or newer.

npm install
npm test
npm run check
npm run build

dist/index.js is committed because GitHub Actions executes the bundled file. Run the build after every source or dependency change and include the resulting bundle in releases.

Release checklist

• Verify tests, type checking, formatting, and that a clean build does not change dist.
• Create an immutable semantic version tag such as v1.0.0.
• Move the major v1 tag to the same verified commit.
• Publish a GitHub Release with upgrade notes.

License

MIT