feat: automatic generation of release notes

[dawidgora]

Add GitHub-style automatic release notes generation

• Add server-side release notes generator that discovers the base tag, gathers merged PRs and contributors, and returns formatted Markdown plus the selected previous tag for reuse.
• Expose a /releases/generate-notes endpoint with form validation, localization strings, and UI wiring (button, previous-tag dropdown, JS handler) on the new release page to trigger note generation.
• Cover the generator with unit tests for default and tag-fallback flows.

---

Screenshots

[wxiaoguang]

Also cc @techknowlogick for further review and help (#35976 (comment)) , in case you already have more discussions.

[dawidgora]

In 1406ccc:

• Added helpers so release notes pick the release immediately before the one being edited, not just the latest one
• This avoids errors when updating notes on older releases because we now compare against the correct predecessor tag.

[dawidgora]

In followup PR, when I find some time I will implement additional configuration for this feature, like it is on GitHub: https://docs.github.com/en/repositories/releasing-projects-on-github/automatically-generated-release-notes

[wxiaoguang]

Too many unnecessary if and ? for "defensive programming"
Most of them should be removed. If you write a if or ? , then you should clearly know that in which case it can happen.

Still many if and ? in code that I don't understand.

---

And #35977 (comment)

Also cc techknowlogick for further review and help (#35976 (comment)) , in case you already have more discussions.

[dawidgora]

Too many unnecessary if and ? for "defensive programming"
Most of them should be removed. If you write a if or ? , then you should clearly know that in which case it can happen.

Still many if and ? in code that I don't understand.

Ok, I made it less defensive now @wxiaoguang

And #35977 (comment)

Also cc techknowlogick for further review and help (#35976 (comment)) , in case you already have more discussions.

We haven't, but @techknowlogick feel free to review my PR

[wxiaoguang]

TBH, still questions (only a quick look, not carefully look into backend code yet)

[dawidgora]

It seems no commits listed when I tested it locally.

@lunny It only works for pull requests. Did you have them, or just commits? It mimics the Github behavior.

[lunny]

It seems no commits listed when I tested it locally.

@lunny It only works for pull requests. Did you have them, or just commits? It mimics the Github behavior.

Okay, I see. I assume it currently collects commits. In the future, we could consider adding an option to collect either commits or pull requests.

[silverwind]

Okay, I see. I assume it currently collects commits. In the future, we could consider adding an option to collect either commits or pull requests.

It's practically useless to me when it does not include commits without a associated pull request, as I think that's a very common scenario, for example when the repo owner does fixups etc.

But if it matches GH (it seems so), I won't block on it.

[wxiaoguang]

A quick test, UI is broken

---

Update: fixed in new commits

[wxiaoguang]

And the UI now looks really strange. (maybe an old problem).

And the new input & button take too much space IMO, maybe need some new design

[wxiaoguang]

A UX problem:

If user has input many message in the textarea, then click the "Generate release notes" button, then their work is lost and no way to undo?

Is it better to "append" but not "replace"?

[dawidgora]

Okay, I see. I assume it currently collects commits. In the future, we could consider adding an option to collect either commits or pull requests.

It's practically useless to me when it does not include commits without a associated pull request, as I think that's a very common scenario, for example when the repo owner does fixups etc.

But if it matches GH (it seems so), I won't block on it.

I can implement that in the following PR, along with other improvements. But first, I'd like to have this one merged.

[silverwind]

Okay, I see. I assume it currently collects commits. In the future, we could consider adding an option to collect either commits or pull requests.

It's practically useless to me when it does not include commits without a associated pull request, as I think that's a very common scenario, for example when the repo owner does fixups etc.
But if it matches GH (it seems so), I won't block on it.

I can implement that in the following PR, along with other improvements. But first, I'd like to have this one merged.

Fine with me.

[silverwind]

Branch needs to be updated and it will likely have some new typescript issues because we enabled strictNullChecks in #35843.

[wxiaoguang]

A UX problem:

If user has input many message in the textarea, then click the "Generate release notes" button, then their work is lost and no way to undo?

Is it better to "append" but not "replace"?

Just tested with GitHub, it "resolves" this problem by disabling the generation when the textarea is not empty:

ps: GitHub has more logic for the "generation", I didn't mean that we must follow GitHub, while I think at least we should avoid surprising end users. Maybe using a modal dialog is better, then the UI can be simplified and more options can be added in the future (for example: add a checkbox to also add commit messages without a PR)

[wxiaoguang]

Will make some changes to address these concerns and fix more UI problems.

[wxiaoguang]

Now a new question:

func findInitialCommit(commit *git.Commit) (*git.Commit, error) {
	// FIXME: this method is inefficient for large repos with long histories, and it doesn't seem right:
	// FIXME: "git diff aaaa...bbbb" doesn't include commits from "aaaa", so the changes in "root commit" won't appear in the tag release's diff.
	// No idea whether we should really make things so complicated.