[agent-guidance] Add release-note rules to .gemini/styleguide.md

[pq]

🤖 Style guide fix-up using the review-tuner skill

See: flutter/dart-intellij-third-party#708

TL;DR

NEXT_RELEASE_NOTES.md gets more human review comments than any other file. State the rules reviewers enforce (own entry only, keep relative links, past tense with a period, user-facing changes only) where the review bot can see them.

What changes

Adds a Release notes item under Key Principles in .gemini/styleguide.md for packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md:

• A PR only adds its own entry (flag edits to other entries, removed blank lines or punctuation, leftover merge-conflict text).
• Links in the file are intentionally relative because the notes are copied to the Flutter website; flag changes that make them absolute.
• Entries are past tense and the sentence ends with a period; the trailing PR link doesn't need one.
• Only user-facing changes belong there; dt tool, CI, test, or internal changes use the release-notes-not-required label.

Why

• NEXT_RELEASE_NOTES.md drew more human inline comments than any other file in a 90-day window: 12 comments from 3 maintainers on 5 PRs (e.g. Show debug-mode message for widget rebuilds in profile mode #9755, Allow flutter SDK binary to be a symlink #9924, Fix Copy as cURL omitting headers and body on failed requests #9963, Adds WebSocket support to Network panel (GSoC'26) #9968).
• The bot commented on this file 3 times but raised none of these points. The rules live in release_notes/README.md and local skills, which the bot doesn't read.

Replay check

Gemini reviewer (flash tier), current vs. proposed style guide, diff + guide only, 3 runs per case (4 motivating PRs above + 2 negatives):

	Current	Proposed
Correct overall	15/18	18/18
Issue raised on motivating PRs	9/12	12/12
False flags on negatives	0/6	0/6

An earlier wording ("end with a period") made the bot flag a missing period after the PR link on a correct entry; the period rule was narrowed to the sentence. Small sample (6 cases), so treat this as a sanity check, not a measurement.

Context: flutter/dart-intellij-third-party#708 · review-tuner skill

Prepared with an agent and reviewed by @pq.

Pre-launch Checklist

General checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I updated/added relevant documentation (doc comments with ///).

Issues checklist

• I listed at least one issue that this PR fixes in the description above.
• I listed at least one issue which has the contributions-welcome or good-first-issue label.
• I did not list at least one issue with the contributions-welcome or good-first-issue label. I understand this means my PR might take longer to be reviewed.

Tests checklist

• I added new tests to check the change I am making...
• OR there is a reason for not adding tests, which I explained in the PR description.

AI-tooling checklist

• I did not use any AI tooling in creating this PR.
• OR I did use AI tooling, and...
  • I read the AI contributions guidelines and agree to follow them.
  • I reviewed all AI-generated code before opening this PR.
  • I understand and am able to discuss the code in this PR.
  • I have verifed the accuracy of any AI-generated text included in the PR description.
  • I commit to verifying the accuracy of any AI-generated code or text that I upload in response to review comments.

Feature-change checklist

• This PR does not change the DevTools UI or behavior and...
  • I added the release-notes-not-required label or left a comment requesting the label be added.
• OR this PR does change the DevTools UI or behavior and...
  • I added an entry to packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md.
  • I included before/after screenshots and/or a GIF demo of the new UI to my PR description.
  • I ran the DevTools app locally to manually verify my changes.

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[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.