screenshot agent compared en to de and flagged layout shift as bug

screenshot agent compared en to de and flagged layout shift as bug

TL;DR

Fixes the screenshot agent flagging expected German text expansion as a layout bug. Compare each locale against its own baseline, not against English. Use when German screenshots fail against English baselines. Not for real truncation bugs.

The error

Screenshot diff failed: de page differs from en baseline by 34 percent pixel diff from text expansion.

Fix it

Step 1: Confirm the diff is only text length

node -e "console.log('review the diff image: longer German words, no broken layout')"

Expected: The layout is correct, just wider text.

Step 2: Baseline per locale

node -e "console.log('capture a de baseline and compare de against de')"

Expected: Each locale compares to its own baseline.

Step 3: Re-run the suite

node -e "console.log('confirm the false failure is gone')"

Expected: The suite passes with per-locale baselines.

When to use this

• A locale fails screenshot diff against the English baseline
• The only diff is longer translated text

When NOT to use this

• Text is actually truncated or overlapping, that is a real bug
• The diff shows missing translations, fix the strings

Tool and version compatibility

• Playwright and Puppeteer screenshot testing
• Any pixel-diff tool

Variant phrasings

fails for every non-English locale

Cross-locale comparison is the wrong strategy. Baseline per locale everywhere.

passes but hides a real truncation

Per-locale baselines need truncation checks as a separate assertion.

Why it happens

German text runs about 30 percent longer than English. Comparing a German screenshot to an English baseline flags normal expansion as a defect, burying real regressions in noise.

Edge cases

• Per-locale baselines must be recaptured when designs change
• Font differences across OSes add diff noise; pin the test fonts
• Combine baselines with explicit overflow assertions

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_12xuw49BWgCb2UHytHS89Q