Reduce token usage when running Review Notes

[dkotter]

What?

Try to reduce the token usage when running Review Notes

Why?

It was reported that it can be easy to run into hourly token limits when running Review Notes. While some of this is unavoidable (for instance, if you have a really long post), we do control how much extra context we send with each request and we can reduce that a bit while still maintaining quality results.

How?

• For each block being reviewed, we send the content of that block and a certain amount of content around that block. Previously that was set to up-to 2000 characters before and after. This PR reduces that to 800
• We had extra instructions around this context and that has been removed (similarly to how we removed this from alt text generation)

In testing on a fairly short article (12 paragraphs, 5 headings), here's the before and after token usage:

Before	After	Savings
27,237 prompt tokens	20,224 prompt tokens	29.55% reduction

Use of AI Tools

None for the code in this PR. Did use Claude Code running Opus 4.6 to build a helper plugin to log token usage to the debug log

Testing Instructions

1. Pull this PR down and run npm i && npm run build
2. Enable the Review Notes experiment
3. Create a post
4. Trigger Review Notes from the sidebar
5. Ensure it still works as expected

Changelog Entry

Changed - Reduce the context we send when running Review Notes to decrease the amount of tokens used.

[github-actions]

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Co-authored-by: dkotter <dkotter@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.44%. Comparing base (219f424) to head (7bf85be).
⚠️ Report is 22 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #434   +/-   ##
==========================================
  Coverage      68.44%   68.44%           
  Complexity       846      846           
==========================================
  Files             56       56           
  Lines           4095     4095           
==========================================
  Hits            2803     2803           
  Misses          1292     1292           

Flag	Coverage Δ
unit	68.44% <ø> (ø)

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[jeffpaul]

Tested Review Notes with this change and things continue to work as expected