Validate screenshot and viewer HTML quality for PR evidence. Run this after adding or modifying images under .agents/evidence/pr/ or .agents/recordings/, or after generating a new viewer HTML file. Combines image quality checks (resolution, blankness, file size) with Playwright-based viewer rendering verification.
SkillScore100Maintained
Automatic
◆QA & Test Engineering pack
Last verified 8/10/2026
What it changes
Passed 22 of 22 test cases with the skill, and 11 of 22 without it.
Without skill50%
With skill100%
Checks it passed that the model alone missed
400x400
uv pip install playwright
regenerate from trace JSONL
and 8 more in the full report
11 fixed11 passed either way0 still failing0 broke
Pass-rate lift
+50 pp
Tokens
-24%
Agent turns
0%
Response time
-66%
Model gemini-3.6-flashMeasured 8/10/2026v122 of 22 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 11 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 11
Prompt
To run trace viewer HTML verification, Playwright and browser dependencies must be installed first. What two CLI commands set up Playwright and Chromium?
What was checked, without and with the skill
Checked
Without skill
With skill
uv pip install playwright
Missed
Passed
playwright install chromium
Passed
Passed
case-11 · gemini-3.6-flash · 8/10/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md70 linessingle file
Screenshot Validation
Validate that evidence images and viewer HTML files meet quality standards before committing. This catches issues that would otherwise fail CI or produce misleading PR evidence.
Image quality check
Checks PNG/JPG/GIF/WEBP files for:
Minimum dimensions: 400x400 pixels (hard fail)
Desktop viewport width: >= 1280px (warning if narrower)
File size: <= 5MB (warning if larger)
Blankness detection (PNG only): fails if > 90% of pixels are white/transparent
Run on specific files or directories
uv run python scripts/check_screenshots.py .agents/evidence/pr/
uv run python scripts/check_screenshots.py .agents/recordings/
uv run python scripts/check_screenshots.py path/to/specific-image.png
Run on git-staged images
scripts/check_screenshots.sh
This shell wrapper automatically finds staged PNG/JPG files and runs the quality check on them — useful as a pre-commit sanity check.
Viewer HTML rendering verification
Uses Playwright (headless Chromium) to verify that generated viewer HTML files actually render correctly — not just raw JSON or Python errors.
Checks:
No JavaScript errors on page load
Normal traces render a sidebar with entries and a detail panel
Empty embedded traces render the explicit "No API calls captured" state
Body text doesn't contain raw JSON dumps or Python tracebacks