KAFKA-20362: Auto-fill PR reviewers in PR description

[mingyen066]

When a pull request submit review event is triggered (comment,
request changes, or approval), this change automatically adds the
reviewer to the Reviewers trailer in the PR body.

Note that comment will NOT trigger the auto-fill process.

This eliminates the need to manually run committer-tools/reviewers.py
before merging. The reviewer's name and email are resolved from their
most recent commit in the repo, falling back to their GitHub profile.

Changes:

• pr-reviewed.yml: save reviewer login to artifact on review events
• pr-linter.yml: pass reviewer login to pr-format.py
• pr-format.py: resolve reviewer identity via GitHub API and append
  to the Reviewers trailer using git interpret-trailers

Testing:

$ python -c "
from importlib.machinery import SourceFileLoader
m = SourceFileLoader('pr_format',
'.github/scripts/pr-format.py').load_module()
print(m.resolve_reviewer('mingyen066'))
print(m.resolve_reviewer('antirez'))
print(m.resolve_reviewer('torvalds'))
"
# Tier 1 hit: found name and email from repo commit history
('Ming-Yen Chung', 'mingyen066@gmail.com')
# Tier 1 miss, Tier 2 hit: found email from GitHub profile
('Salvatore Sanfilippo', 'antirez@gmail.com')
# Both miss email: placeholder used for committer to fix manually
('Linus Torvalds', 'torvalds-email-not-found')

$ python -c " from importlib.machinery import SourceFileLoader m =
SourceFileLoader('pr_format',
'.github/scripts/pr-format.py').load_module() existing = ['Chia-Ping
Tsai <chia7712@gmail.com>, Ming-Yen Chung <mingyen066@gmail.com>']
print(m.already_exists('chia7712@gmail.com', existing))
print(m.already_exists('someone@gmail.com', existing))
print(m.already_exists('Chia7712@Gmail.com', existing)) " True False
True

$ python -c " from importlib.machinery import SourceFileLoader m =
SourceFileLoader('pr_format',
'.github/scripts/pr-format.py').load_module() body = 'This is a PR
description.\n' result = m.update_reviewers_trailer(body, 'Reviewers:
Alice <alice@test.com>') print(result) " This is a PR description.

Reviewers: Alice <alice@test.com>

Reviewers: TaiJuWu tjwu1217@gmail.com, Chia-Ping Tsai
chia7712@gmail.com

[chia7712]

what happens if there are two reviewers adding the comment concurrently?

[mingyen066]

Each review comment triggers an independent pr-reviewed workflow run with its own workflow_run.id, so pr-format.py correctly receives each reviewer's login separately via its own artifact. The only possible race condition is if two pr-format.py runs read and update the PR body at the same time — the second write could overwrite the first, losing a reviewer. The race window is only between reading the PR body and writing it back in pr-format.py, which is a short window. Even if it does happen, the lost reviewer will be re-added on their next review comment. If we want to eliminate this entirely, we can add a concurrency group to pr-linter.yml to serialize runs per PR.

[chia7712]

I guess the worst that happens is an unlucky reviewer gets dropped?

[mingyen066]

that's right.

[mingyen066]

I've tested in my fork. It works well
mingyen066#4

[mjsax]

I just notice that we get Reviewers filled in automatically, but I find it not helpful at this point. It's does never use the correct email address. -- Can we fix this? If not, I would rather not have this action at all (at this point, I find it personally very annoying TBH).

For example:

This is not helpful at all. I need to update this manually anyway.

[mingyen066]

@mjsax Sorry for the noise. I'll fix it right away.

[mingyen066]

@mjsax Thanks for the feedback! Opened #22108 to skip the auto-fill when no reliable email can be resolved. Hope it's more helpful next time 😅

[chia7712]

@UladzislauBlok Out of curiosity—since your email is hidden on your GitHub profile, are you okay with using your real email for the commit message? I know we can find it in your commit history anyway, but I wanted to check if you'd prefer to keep it private