[chubes4]

Related issues

• Related to Spike: Studio Code reads the WordPress source instead of being taught WordPress #5146, where the agent eval surfaced it

How AI was used in this PR

Claude (via the Pi coding agent in a Roadie session) found this while comparing Studio Code agent runs, traced it to the code, wrote the change and its test, and ran the verification below. Opened as a draft for human review.

Proposed Changes

• Gutenberg logs block validation problems as console-style format strings, for example Expected attribute \%s` of value `%s`, saw `%s`., followed by the values. validate_blocks` joined these pieces as they came, so the agent read the template with its placeholders still in it and the values tacked on afterwards.
• Placeholders are now filled in from the values that follow them, so each issue reads as one sentence.

Before:

Expected attribute `%s` of value `%s`, saw `%s`. class wp-block-heading has-text-color wp-block-heading

After:

Expected attribute `class` of value `wp-block-heading has-text-color`, saw `wp-block-heading`.

Testing Instructions

• With a site running, call validate_blocks on <!-- wp:heading {"style":{"color":{"text":"#faf8f5"}}} --><h2 class="wp-block-heading" style="color:#faf8f5">Hi</h2><!-- /wp:heading -->. The issue reads like the "After" output above. This was checked against a running site's editor.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 777e460 vs trunk

app-size

Metric	trunk	777e460	Diff	Change
App Size (Mac)	930.72 MB	930.72 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	777e460	Diff	Change
load	1178 ms	1145 ms	33 ms	⚪ 0.0%

site-startup

Metric	trunk	777e460	Diff	Change
siteCreation	8555 ms	8576 ms	+21 ms	⚪ 0.0%
siteStartup	5900 ms	5902 ms	+2 ms	⚪ 0.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)